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VERSION 2
STANDARDS / MANUALS / GUIDELINES FOR SMALL HYDRO DEVELOPMENT
SPONSOR: MINISTRY OF NEW AND RENEWABLE ENERGY
GOVERNMENT OF INDIA
GUIDELINES FOR
MONITORING CONTROL AND PROTECTION OF SHP STATIONS
LEAD ORGANISATION:
ALTERNATE HYDRO ENERGY CENTRE INDIAN INSTITUTE OF TECHNOLOGY, ROORKEE
CONTENTS
ITEMS PAGE NO.
1.0 INTRODUCTION 1
1.1 OBJECTIVE 1
1.2 GENERAL 1
1.3 REFERENCES AND CODES 2
SECTION – I GENERAL TECHNICAL CONSIDERATIONS FOR
PREPARING SPECIFICATIONS
3
1.0 MONITORING OF SHP 3
1.1 SYSTEMS FOR MONITORING 3
1.2 REQUIREMENTS OF MONITORING SYSTEM 5
1.3 LEVELS OF MONITORING 6
1.4 CONTROL OF UNITS OF SMALL HYDROPOWER PLANT
6
1.5 PROTECTION OF SHP GENERATING UNITS 17
1.6 GENERATOR CONNECTED IN PARALLEL TO GRID
31
1.7 GENERATORS CONNECTED IN PARALLEL ON A COMMON BUS
31
1.8 PROTECTION GROUPS 32
1.9 PROTECTION OF POWER TRANSFORMERS 33
1.10 FIRE PROTECTION SYSTEM 33
SECTION – II TECHNICAL SPECIFICATIONS FOR CONTROL, PROTECTION & METERING ( MICRO HYDEL UPTO 100 KW)
36
2.1 SCOPE 36
2.2 APPLICABLE STANDARDS 36
2.3 DESIGN CRITERIA 36
2.4 PROTECTION AND METERING 37
2.5 TESTS 39 SECTION - III TECHNICAL SPECIFICATIONS
CONTROL, PROTECTION AND METERING (FOR SHP ABOVE 100KW TO 1000KW)
40
3.1 SCOPE 40
3.2 CONTROL EQUIPMENT 40
3.3 SYNCHRONIZATION 40
3.4 ALARM AND ANNUNCIATION 41
3.5 METERING 41
ITEMS PAGE NO.
3.6 PROTECTION RELAYS 41
3.7 UNIT CONTROL BOARD 41
3.8 COMPLETENESS 41
3.9 SPARE PARTS & TOOLS 41
3.10 DOCUMENTATION 42
3.11 STANDARDS 42
3.12 FUNCTIONAL REQUIREMENTS 44
3.13 UNIT CONTROLLERS 44
3.14 PROTECTION AND METERING DETAILS 45 3.15 METERING SYSTEM 47
3.16 UNIT CONTROL BOARD/CONTROL PANEL 48 3.17 SYNCHRONIZING PANEL 48
3.18 ANNUNCIATION SYSTEM 49
3.19 FACTORY TESTING 50
3.20 SITE TESTING 50
3.21 DRAWINGS 51
3.22 SPARE PARTS & TOOLS 51
SECTION -IV TECHNICAL SPECIFICATION FOR CONTROL PROTECTION, METERING, SUPERVISORY CONTROL AND DATA AQUISITION SYSTEM (SCADA)
52
4.0 SCOPE 52
4.1 APPLICABLE STANDARD 52
4.2 CONTROL AND MONITORING SYSTEM 52
4.3 CONTROL AND MONITORING OF PLANT EQUIPMENT
54
4.4 MANUAL CONTROL, METERING AND PROTECTION SYSTEM
75
4.5 SUPERVISORY CONTROL AND DATA ACQUISITION (SCADA) SYSTEM
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SECTION -V TECHNICAL SPECIFICATION FOR CONTROL PROTECTION, METERING AND SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA)
95
5.0 SCOPE 95
5.1 APPLICABLE STANDARD 95
5.2 CONTROL AND MONITORING SYSTEM 96
5.3 CONTROL AND MONITORING OF PLANT EQUIPMENT
96
5.4 MANUAL CONTROL, METERING AND PROTECTION SYSTEM
123
ITEMS PAGE NO.
5.5 SUPERVISORY CONTROL AND DATA ACQUISITION (SCADA) SYSTEM
138
5.6 COMMUNICATION LINK 147
5.7 FACTORY TESTS FOR UNIT CONTROL SWITCHBOARDS
150
5.8 FIELD TESTS FOR UNIT CONTROL SWITCHBOARDS
151
5.9 ADDITIONAL FACTORY AND FIELD TESTS FOR DISTRIBUTED CONTROL SYSTEMS
151
5.10 DATA/ DOCUMENT TO BE FURNISHED BY THE BIDDER
152
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GUIDE LINES FOR TECHNICAL SPECIFICTION FOR MONITORING CONTROL AND PROTECTION OF SHP STATIONS
1.0 INTRODUCTION
1.1 OBJECTIVES This guide is intended to assist in preparation of specification for monitoring of various parameters of various operations, control and protection of main generating equipment viz turbine, generator, transformer and other associated auxiliaries. 1.2 GENERAL The generating units of a small hydropower plant may have its shaft vertical, horizontal or inclined with the type of turbine selected to suit the site’s physical conditions. Small hydro turbines may be selected as per site conditions, head and discharge available. Small hydro-generator are of the alternating current type and may be either synchronous or induction type. Usually small hydro units up to 5 MW are expected to require minimum amount of field assembly and installation work. While machine having capacity from 5 MW to 25 MW may have slow speed, large diameter and with split generator stator that require final winding assembly in the field. Mini & micro power stations are generally provided system suiting to these being run unattended or with few attendants while bigger machines up to 5 MW capacity have more elaborate arrangement of control monitoring and protection. Machine having capacity up to 25 MW and provision of parallel operation with other systems will have more comprehensive control, monitoring & protection system. This guide, therefore, describes control, monitoring and protection requirement of small hydro power plants in following categories: Section-I General technical considerations for preparing specifications Section- II Technical Specification for MHP having capacity upto100KW, Section-III Technical Specification for SHP having capacity above 100KW to1000KW, Section-IV Technical Specification for SHP having capacity above 1MW to 5 MW Section -V Technical Specification for SHP having capacity above 5MW to 25 MW. This guide will serve as a reference document along with available national & international codes standards, guide & books. For the purpose of convenience Section-I of this guide has been subdivided as follows
• Monitoring • Control • Protection
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1.3 REFERENCES AND CODES IEEE Std 1020 - IEEE guide for control of small hydro electric power
plants IEEE Std 1010 - IEEE guide for control of hydro electric power plants IEEE Std 60545:1976 - Guide for commissioning operation and maintenance of
Hydraulic Turbines IEC 61116:1992 - Electro mechanical guide for small hydroelectric
installations IEEE std 1046 - IEEE application guide for distributed digital control
and monitoring for power plants IEEE std. 1249 - IEEE guide for computer–based control for power
plant automation IEEE std. C 37101 - IEEE guide for generator ground protection IEEE std. C 5012 - IEEE standard for salient pole 50 Hz and 60 Hz
synchronous generator and generator / motors for hydraulic turbine application rated 5 MVA and above
IEEE std 4214 - IEEE guide for preparation of excitation system specification
ANSI/ IEEE std 242:1996 - IEEE recommended practice for protection and coordination of industrial and commercial power systems
ANSI/ IEEE std C 372-1987 - IEEE standard electrical power systems device function numbers
ANSI/ IEEE std C 37.95 : 1974 - (R1980) IEEE guide for protective relaying of utility ANSI/ IEEE std C 37.102:1987 - IEEE guide for generator protection MASON, CR - Art & science of protective relaying 1956 AHEC/PFC/FINAL REPORT 2002
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SECTION – I GENERAL TECHNICAL CONSIDERATIONS FOR PREPARING SPECIFICATIONS 1.0 MONITORING OF SHP Monitoring of operating parameters of the generating unit and their auxiliaries is very important for the life and optimum utilization of available discharge for generation. The efficient running of unit require regular monitoring. The primary input data and generation output data are monitored periodically. The details of data required for monitoring performance of a generating station is as following. 1.1 SYSTEMS FOR MONITORING 1.1.1 Water Conductor System
• Storage level at dam / barrage / weir • River discharge • Headrace channel discharge • Discharge at outlet of disilting basin • Forebay level • Discharge of spillway • Penstock pressure • Tail water level
1.1.2 Hydro-mechanical Parameters
• Turbine and accessories o Pressure and levels in oil pressure system o Bearing temperatures (oil & pads) o Oil level in bearing sumps (if provided) o Cooling water pressure and temperatures o Clean water pressure for shaft gland o Vibration in shaft for large machines o Status of inlet and other valves.
• Generator and accessories o Stator winding temperature o Rotor winding temperature o DE/NDE end bearing temperatures o Cooling water and air temperatures o Air gap monitoring
• Transformers o Winding temperature o Oil temperature o Oil level o Cooling water temperature and pressures
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1.1.3 Electro-mechanical Operating Parameters
• Turbine & accessories o Speed o Guide vane opening & limits (precent) o Runner blade opening in Kaplan Turbine (percent) o Nozzle opening in impulse turbine (percent)
• Generator & auxiliaries o Governor actuator balance current (Amp) o Generated power (kW or MW) o Generated hour (kWh) o Kilovolt ampere (kVA) o Kilovolt ampere reactive (kVAR) o Power factor (PF) o Frequency (Hz) o Excitation voltage (Volts) o Excitation current (Amp) o Recorder for kW, Hz, kWh etc
• Transformers o Tap position o HV/LV current o Primary/ secondary voltage
• Grid system & transmission line o Grid voltage o Grid frequency o Power export / import (kW) o Current (Amp) o Kilowatt hour (kWh) export / import
• Station auxiliaries o Voltage and current on LT AC system o Kilowatt hour (kWh) o Diesel generator running hour, kWh & other parameters o Drainage & dewatering system
Running hours of pumps Water level in sump
o Fire extinguisher – periodical testing o Battery set- Regular monitoring as per manufacturers recommendations o Battery chargers & distribution boards – voltage current etc. o Air compressors – HP /LP pressures and running hours o OPU system
Running hours of pumps Level in pressure accumulators Pressure of oil
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1.2 REQUIREMENTS OF MONITORING SYSTEM 1.2.1 Instrument Transformers & Sensors CTs & VTs Current and voltage transformers of rated voltage and appropriate ratio, class of accuracy is selected as per the requirement of the system. Sensors The sensors for temperatures, pressures, levels speed are installed at the proper location. 1.2.2 Indicating Meters Analogue type of meters, separate for each parameter with selector switches etc were being used earlier installed on control panels. Now a days digital meters are being used for such parameters. Digital multifunction meters are now in use, only one meter provides several parameters an selection, as well as provides routine display. Few analogue meters like power meters (kW), voltmeters, ameters with selector switches are provided for operational facilities. 1.2.3 Temperature Scanners Digital temperature scanners indicating the temperatures of stator winding, bearing pads, oil coolers etc. are provided and installed on the generator control panels. These scanners get the signals from the sensor installed at specific location preferably through screened cables. 1.2.4 Indicating Lamps Indicating lamps of suitable colours as per code and practices should be provided on control panels for indication status of machine and various auxiliaries, pumps, electrical equipment like breaker, isolator, AC/DC supply system etc. Lists of such indication and relays are enclosed as Annexure-I&II. 1.2.5 Alarm & Annunciations The protection system relays and auxiliary relays also provided signals to alarm and annunciation system. A set of annunciation windows are provided on control panels for each fault clearing relay with accept test and reset facility through push buttons. Alarm and trip annunciation indicate the fault and advise operating personnel of the changed operating conditions. 1.2.6 PLC Based System Recently control of machine and auxiliaries is done through PLC based control system automatically in addition to manual systems with local and remote facilities. The data
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are acquired through sensors and operation of machine is achieved on present values through PC Monitors etc. The PLC will acquire data from generating units, transformers, switchgears auxiliaries through transducers / sensors/ CTs/ VTs wherever signals are week, noise level is high shielded cables should be used for carrying data / signals. For sending output signal PLC will use relays for operating breakers etc and comparators for giving ON/OFF signal. 1.3 LEVELS OF MONITORING Normally two levels of monitoring is provided in SHP as per recommendation of IEC 1116. The levels are:
• Alarm • Tripping
In case of manned power plant ‘alarm’ comes first so as to make the operator alert if
no corrective action is possible then tripping command with indication / hooter and annunciation will be there.
But in case of unattended power plant direct tripping command will be initiated and
shut off the facility to avert possibility of any damage to the plant.
1.4 CONTROL OF UNITS OF SMALL HYDROPOWER PLANT 1.4.1 GENERAL For small hydro installation simplicity of control system is advised, however, the sophistication of control should be based on the complexity and size of the installation, without compromising unit dependability and personal safety. Simplicity of control is desirable to keep total cost of installed equipment as well as cost of maintenance, repair and tests at economical level. Moreover a simpler system is more reliable as compared to complex one. 1.4.2 GENERATOR CONNECTION TO SYSTEMS 1.4.2.1 Synchronous Generator For conventional method of synchronizing the generator is started, accelerated to near synchronous speed and excitation is applied. The voltage and the frequency are matched and unit is synchronized to the system, by closing generator circuit breaker or contactor, when done perfectly no current surge will occur. Normally both manual and automatic synchronizing of generator are provided. In addition the speed of some types of turbines under no load conditions is so sensitive to small adjustments in runner blade angle or inflow as to make only automatic synchronizing practical. Small hydropower plants will certainly require unattended automatic synchronizing. Manual synchronizing necessitates availability of continuous display of voltage, frequency, phase angle and devices to control voltage and speed on the control panel. Transducers or signal transmitters are provided either at the control panel or at the equipment.
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1.4.2.2 Induction Generator For conventional method of connecting induction generator to the grid, the generator is started and accelerated to synchronous speed. In fact, the rotor speed of generator shall be (1% slip) more than grid frequency. This is done to avoid monitoring action of generator. Once the generator frequency matches with grid frequency the generator breaker is closed. Now the generator is connected with the grid and running at no load. At this stage grid power factor is to be checked and capacitor banks are switched on as per requirement to provide necessary reactive power and further loading of unit is done upto full load. All these functions can be performed manually as well as automatically through PLC, computer, microprocessor based control system. For smaller machines which are unattended provision of integrated digital control & SCADA system is preferred. 1.4.2.3 Status and Alarm Requirements
• Unit ready to start • Breaker position (no alarm if manual operation only) • Intrusion alarm • Fire alarm • Emergency status alarm (requires immediate attention0 • General status alarm (response can be differed) • Trash rack differential alarm • Unit stopped (when not required) • Unit turning (when not required) • High bearing temperatures • Loss of lubrication or cooling or both • Low hydraulic system pressure • Incomplete start or stop sequence • Loss of power
1.4.3 UNIT CONTROL The control logic system for small hydro start stop sequencing can be provided by hardwired relay logic, programmable controllers microprocessor based systems or a combination of these. The unit control system should be designed to perform following functions:
• Data gathering and monitoring • Start stop control sequence • Annunciation & alarm conditions • Temperature monitoring • Metering & instrumentation
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• Event recording • Synchronizing and connecting the unit to grid • Control of real & reactive power
The unit control system must be able to provide startup and shutdown sequencing
under both normal and abnormal conditions. Under normal conditions, the unit is started and stopped in manner that produces minimal disturbance to the system. For instance of normal stop sequence entails a controlled unloading of machine and when completely unloaded, the generator breakers or contactor is tripped. On the other hand protective relay operation will initiate immediate tripping of the unit and complete shutdown as quickly as possible.
For certain mechanical troubles the unit is unloaded as quickly as possible before
tripping, in order that the potential damage from over speed is avoided. The unit control system, in order to control and monitor various control sequences,
must interface with number of plant systems, including the following:
• Auxiliary system – pumps & valves • Governor load control rollers – setters, solenoids & brake control • Excitation – setters, contactors and circuit breakers
Typical startup and shutdown sequence are shown in fig. 1-3 for a Francis turbine
unit, which, for the sake of illustration, are shown as including synchronous generator and governing system.
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Fig. 1: Typical Start Sequence of Synchronous Generator
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Fig. 2: Typical Normal Shut Down and Mechanical Trouble Stop Sequence of
Synchronous Generator
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Fig. 3: Typical Electrical Trouble Stop Sequence for Synchronous Generator
1.4.4 CONTROL FUNCTIONS There are many functions to be controlled in a small hydropower system. For example turbine governor controls the speed of turbine, plant automation covers operations as auto start, auto synchronization, remote control startup or water level control and data acquisition and retrieval covers such operation as relaying plant operating status, instantaneous system efficiency or monthly plant factor. 1.4.4.1 Turbine Control This is the speed / load control of turbine in which governor adjusts the flow of water through turbine to balance the input power with load.
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In case small plants in the category of micro hydel (100 kW unit size), load controllers are used, where excess load is diverted to dummy load to maintain constant speed. With an isolated system, the governor controls the frequency of the system. In interconnected system, the governor may be used to regulate unit load and may contribute to the system frequency control. Figure 4 shows the different types of control applicable to turbines.
Fig. 4: Turbine Control 1.4.4.2 Generator Control This is the excitation control of synchronous generator. The excitation is an integral part of synchronous generator which is used to regulate operation of generator. The main functions of excitation system of a synchronous generator are:
• Voltage control in case of isolated operation and synchronizing • Reactive power or power factor controls in case of inter connected operation.
The different generator controls are shown in fig. 5.
Fig. 5: Generator Controls
1.4.4.3 Plant Control Plant control deals with the operation of plant. It includes sequential operation like startup, excitation control, synchronization, loading unit under specified conditions, normal shutdown, emergency shutdown etc. The mode of control may be manual or automatic and
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may be controlled locally or from remote location. Plant control usually include monitoring and display of plant conditions. Different plant controls are given in fig 6.
Fig. 6: Overview of Plant Automatic Control
1.4.5 CONTROL OF HYDROELECTRIC POWER PLANTS 1.4.5.1 Vertical Array of Control System For hydroelectric power plants the components of the control system can be shown in vertical array as shown in fig 7.
Fig. 7: Hierarchy of Controls of Hydropower Plants
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• At lowest level (process level) process which includes, generator exciter, turbines, switchgears, motors, pumps, valve etc is being controlled.
• At middle level there is control interface equipment which sends signals to the apparatus from controlling equipment and for apparatus to transmit data back to controlling equipment. Auxiliary contacts of motor starter, relays instrument transformer signal conditioner, transducers or other interface devices.
• At top level there is controlling system which initiates control signals and receives the data transmitted from apparatus control interface equipment. At this level itself human-machine interface is included.
1.4.5.2 Categorization of Control System The control system can further be defined by identifying following three categories of control:
• Location: a. Local - control is local at the controlled equipment within the sight of
the equipment b. Centralised - control is at other place, but within the plant c. Off site - control is at remote place which may be quite far from the
plant (Remote) • Control mode:
a. Manual - Each operation requires a separate and distinct initiation. However it may be applicable for any of the three locations
b. Automatic - With single initiation several operations in appropriate (PLC/ computer/ sequence are done. This system can also be applicable to any
Microprocessor of the above three locations Controlled)
• Operation (supervision) a. Attended - Operators are all the time available at the plant to perform
control action either locally or centralized control b. Unattended - Operating staff is not available at the plant. There may be
occasional visits by operation & maintenance people to ensure security of plant.
1.4.5.3 Information and Control Signals Following four types of signals are provided between control board and particular equipment
• Analog inputs for variable signals from CTs, VTs, RTDs, pressure, flow, level, vibration etc.
• Digital inputs provides digitalized values of variable quantities from the equipment • Digital outputs – command signals from control boards to equipment • Analog outputs – transmit variable signals from control to equipment e.g. governor,
voltage regulator etc.
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1.4.5.4 Communication Links a. Communication links with remote control Following methods are available for implementing control from a remote location:
• Hardwired communication circuits (telephone type line, optical cables etc.) • Leased telephone lines • Power line carries communication system • Point to point radio • Microwave radio • Satellite
Metallic circuit in hardwire communication circuits and leased telephone lines,
requires special protection for equipments and personals against ground potential rise (GPR) due to electric system fault, since the hydro-generator is source of fault current. GPR is also caused by lightening transmitted through power lines entering the power plant. As such suitable mitigation has to be provided.
Power line carrier including insulated ground wire system can be used for
communications purposes. This method couples a high frequency signal on the power line or insulated ground wire and is decoupled at an offsite point.
Space radio can be used, utilizing power frequencies and micro wave radio can be
practical if hydro plant owner has an existing microwave system. b. Communication with control boards
Data and control signals of following equipments will be required to be transmitted between control board & equipments.
• Generator neutral and terminal equipment • Head water and tail water level equipment • Water passage shut off or bye pass valves gates etc. • Turbine • Unit transformer • Circuits breaker and switches • Generator • Intake gates or main inlet valve and draft tube gates • Turbine governing system • Generator excitation system
The communication link between control board and equipment should be reliable.
c. Communications with Auxiliaries Data and control signals of following auxiliaries/ equipments will be required to be transmitted between control board and equipments.
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• Fire protection • AC Power supply • DC Power supply • Service water • Service air • Water level monitoring • Turbine flow monitoring
1.4.6 MODERN PRACTICE REGARDING GOVERNOR AND PLANT CONTROL 1.4.6.1 Previous Practice Control of a hydro plant generating unit was typically performed from central control board located in centralize control room. The control board contained.
• Iron vane meters • Hardwired control switches • A large number of auxiliary relays to perform unit start / stop operations • All the sensors and controls required to operate unit or units were hardwired to control
panels allowing control of power station from cotnralised control room 1.4.6.2 Modern Practice Modern digital integrated control and protection system including programmable logistic controller (PLCs), distributed computer control system or personal computer control system not only provide supervisory control and data acquisition (SCADA) but also flexibility in control, alarm, sequencing, remote communication in a cost effective manner and has been specifically recommended for SHPs in India, under UNDP – GEF projects. Control functions of small hydro plants are standardized in following US standards
a. IEEE guide for control of small hydro electric plants, “ANSI/IEEE standard 1011, 1990’.
b. IEEE guide for control of hydroelectric power plants “ANSI/IEEE standard 1010, 1991.
Specific hardware or software to be utilized for implementation is not however
addressed in these standards. Architecture and communication are two potential problem area for computerized
control system. In 1990, the International Organisation for standardistion developed a model for open
architecture and protocol, know as SI (open system interconnection) – ISO mode. Programmable Logic Controllers (PLC) type plant controllers combine with PC based
SCADA systems are used as Governors and for plant control & data acquisition. This makes the system less costly and reliable and therefore, can be used for small hydropower generation control.
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Personal computer based dedicated digital control system can perform all functions of governing, unit control, protection and also data acquisition & storage and are more economical and reliable. These dedicated systems with back up manual control facility of turbine control in emergency by dedicated semi automatic digital controllers can be a low cost option for small hydropower station.
1.5 PROTECTION OF SHP GENERATING UNITS 1.5.1 GENERAL Small hydro turbine-generators should be protected against mechanical, electrical, hydraulic and thermal damage that may occur as a result of abnormal conditions in the plant or in the utility system to which the plant is electrically connected. The abnormal operating conditions that may arise should be detected automatically and corrective action taken in a timely fashion to minimize the impact. Relays (utilizing electrical quantities), temperature sensors, pressure or liquid level sensors, and mechanical contacts operated by centrifugal force, etc., may be utilized in the detection of abnormal conditions. These devices in turn operate other electrical and mechanical devices to isolate the equipment from the system. Where programmable controllers are provided for unit control, they can also perform some of the desired protective functions. Operating problems with the turbine, generator, or associated auxiliary equipment require an orderly shutdown of the affected unit while the remaining generating units (if more than one is in the plant) continue to operate. Alarm indicators could be used to advise operating personnel of the changed operating conditions. Loss of individual items of auxiliary equipment may or may not be critical to the overall operation of the small plant, depending upon the extent of redundancy provided in the auxiliary systems. Many auxiliary equipment problems may necessitate loss of generation until the abnormal conditions has been determined and corrected by operating or maintenance staff. The type and extent of the protection provided will depend upon many considerations, some of which are: (1) the capacity, number, and type of units in the plant; (2) the type of power system; (3) interconnecting utility requirements; (4) the owner’s dependence on the plant for power; (5) manufacturer’s recommendations; (6) equipment capabilities; and (7) control location and extent of monitoring. Overall, though, the design of the protective systems and equipment is intended to detect abnormal conditions quickly and isolate the affected equipment as rapidly as possible, so as to minimize the extent of damage and yet retain the maximum amount of equipment in service. Small hydroelectric power plants generally contain less complex systems than large stations, and therefore tend to require less protective equipment. On the other hand, the very small stations should be typically unattended and under automatic control, and frequently have little control and data monitoring at an off-site location. This greater isolation tends to increase the protection demands of the smaller plants.
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An inherent part of the power plant protection is the design of the automatic controls to recognize and act on abnormal conditions or control failures during startup. Close coordination of the unit controls and other protection is essential. 1.5.2 EQUIPMENT TROUBLE 1.5.2.1 Plant Mechanical Equipment Troubles 1.52.1.1 Turbines
(a) Excessive vibration (b) Bearing problems (c) Over speed (d) Insufficient water flow (e) Shear pin failure (f) Grease system failure
1.5.2.1.2 Hydraulic Control System
(a) Low accumulator oil level (b) Low accumulator pressure (c) Electrical, electronic or hydraulic malfunctions within the governing or gate
positioning system 1.5.2.1.3 Water Passage Equipment
(a) Failure of head gate or inlet valve (b) Head gate inoperative (c) Trash rack blockage (d) Water level control malfunction
1.5.2.2 Plant Electrical Equipment Troubles 1.5.2.2.1 Generator
(a) Abnormal electrical conditions (b) Stator winding high temperature (c) Low frequency (d) Bearing problems (e) Motoring (f) Fire (g) Excessive vibration (h) Cooling failure (i) Over speed
1.5.2.2.2 Main Transformer
(a) Insulation failure (b) High temperature (c) Abnormal oil level (d) Fire
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1.5.2.2.3 Generator Switchgear and Bus
(a) Electrical fault (b) Mechanical failure (c) Loss of control power
1.5.2.3 General Plant Troubles 1.5.2.3.1 Station Service
(a) Transformer failure (b) Unbalanced current (c) DC System Trouble (d) Station Air System Trouble (e) Service Water System Trouble (f) Flooding (g) Fire (h) Unauthorized Entry (i) Protection or Control Logic System Malfunction (j) Water level Monitoring System Malfunction
1.5.2.4 Utility System Troubles Utility line faults and other abnormal utility system conditions should be detected and the plant be disconnected from the utility system. Abnormal utility system conditions include the following situations:
a. Ground or phase faults b. Single phasing c. Abnormal voltage d. System separation (islanding)
Coordination with the utility is needed in selecting specific protective equipment,
particularly for line fault detection. 1.5.3 DEVICES USED IN A TYPICAL PROTECTION SYSTEM There are numerous ways of providing the functional protective requirements of the plant. While standard devices are generally available that can provide the protective functions required, however each station should have specific design suitable for protection requirements of the power plant equipment as well as the interconnection. The following section describes components of a typical protection system that might be applied to a small hydro plant. Discussions and diagrams are included to illustrate location and arrangement of relays. 1.5.3.1 Protective Devices 1.5.3.1.1 Temperature A temperature device, possibly incorporating display and contacts for alarm annunciation and tripping to monitor bearing stator and transformer winding temperatures.
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Resistance temperature devices operating relays can also be used to detect generator stator overheating. 1.5.3.1.2 Pressure and Level Pressure and level switches installed in the turbine air and oil systems, to alarm, block startup, or trip, as necessary. 1.5.3.1.3 Over and under speed Direct-connected or electrically driven speed switches for alarm, control, and tripping. 1.5.3.1.4 Vibration Vibration detectors monitoring turbine or generator shaft sections, with alarm and trip contacts. 1.5.3.1.5 Water level A measuring system incorporating level sensors and monitoring equipment, to alarm, trip, or control turbine output on limiting values of headwater or tail water level, or head. 1.5.3.1.6 Fire Sensors located in areas where fire can occur and connected to a central fire monitor for alarm. Small generators usually do not have fire sensors or suppression equipment, since they are not usually enclosed. 1.5.3.1.7 Miscellaneous mechanical Sensing devices are integral to the protected systems, such as automatic greasing system, wicket gate shear pins, transformer, cooling and station sump drainage system. 1.5.3.2 Protective Relay and Protection System 1.5.3.2.1 Features of relays The protective relays stand watch and in the event of failures short circuits or abnormal operating conditions help de-energize the unhealthy section of power system and restrain interference with rest of it and limit damage to equipment and ensure safety of personals. The protective relays should possess following features:
• Reliability – To ensure correct action even after long period of inactivity and also to offer repeated operation under sever condition.
• Selectivity – To ensure that only the unhealthy part of system is disconnected • Sensitivity – Detection of short circuit or abnormal operating condition. • Speed – To prevent and minimize damage and risk to instability of rotating plant.
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• Stability – The ability to operate only under those conditions that calls for its operation and to remain either passive or biased against operation under all other conditions.
1.5.3.2.2 Type of relays There are several types of relays being used for protection systems
- Electromagnetic relays - Static relays - Numerical relays
The old conventional electromagnetic relays are now being replaced with static relays
with are much faster and maintenance free. These relays are more reliable and sensitive. These microprocessor based relays have different protections elements and therefore a separate relay for each protection is not required. A list of protections generally available in these microprocessor based relays is enclosed as Annexure-II. The numerical relays are having LED indications for power ON, trip status for different protection elements, time / current characteristics selected and contacts for trip signals. However, some individual electromagnetic conventional / static relays for few important protections are recommended to be provided as standby relays. • Advantages of numerical relays
It has been a practice to use electro-mechanical / solid state relays for all above protections. The present trend is to use numerical relays which offer many advantages as follows, over the earlier technology.
PARAMETER NUMERIC CONVENTIONAL Accuracy 1% 5%/7.5% Burden <0.5 VA >5 VA Setting Ranges Wide Limited Multi Functionality Yes No Size Small Large Field Programmability Yes No Parameter Display Yes No System Flexibility Yes No Co-ordination Tools Many Two Communication Yes No Remote Control Yes No Special Algorithms Many Limited Special Protections Yes No Self Diagnostics Yes No
The user’s worry that numerical relays are very expensive is now removed due to continuous production, improvement in techniques which have made numerical relays above all, with features listed as above. Numerical relays are more user friendly and are gaining popularity everywhere. Following annexure are enclosed for ready reference
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• Annexure-I - List of SHP Generator panel indications & relays • Annexure-II - List of protection elements in Microprocessor based relays
1.5.3.2.3 Criteria of selection of protection system The designer must balance the expense of applying a particular relay against the consequences of losing a generator. The total loss of generator may not be catastrophic if it represents a small percentage of the investment in an installation. However, the impact on service reliability and upset to loads supplied must be considered. Damage to equipment and loss of product in continuous processes can be dominating concern rather than generating unit. Accordingly there is no standard solution based on MW-rating. However, it is rather expected that a 500 kW, 415 V hydro machine will have less protection as compared to 25 MW base load hydro electric machine. With increasing complications in power system, utility regulation, stress on cost reduction and trends towards automation, generating unit protection has become a high focus area. State of the art, micro controller based protection schemes offer a range of economical, efficient and reliable solution to address the basic protection and control requirements depending upon the size and specific requirement of the plant. 1.5.3.3 Requirements of Protection of Turbine Two level protection is recommended as per IEC 1116. Elements to be considered are:
(a) Speed rotation (b) Oil levels in bearing (c) Circulation of lubricants (d) Oil level of the governing system (e) Oil level of speed increaser (if provided) (f) Bearing temperatures (g) Oil temperature of governing system (h) Oil temperatures of speed increasers (i) Oil pressure of governing system (j) Pressure of cooling water
Immediate tripping is required for a, c, i, and j. While for item b, d, e, f, g and h only
alarm and annunciation is required to alert the operator and take corrective action, but in case corrective action is not taken, tripping will eventually follow. Applying brakes at a particular speed (30% of full speed) is done to reduce time to achieve stand still position of machine.
It is recommended two independent devices must be provided for over speed shut
down on larger machines. One for alarm mostly at 110% and other for tripping at 140%, specially for machines which are not designed for continuous run away speed. 1.5.3.4 Requirements of Protection of Generator Elements to be considered normally are
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a. Stator temperature b. Over current (stator and rotor) c. Earth fault with current limits (stators & rotor) d. Maximum and minimum voltage e. Power reversal f. Over/ under frequency g. Oil level in bearing sumps h. Pad & oil temperature of bearings i. Cooling air temperature
Immediate tripping is required for items b, c, d, e & f while for items a, g, h and i first
alarm and annunciation is required for taking correcting measure and then tripping if correcting measure is not taken within permissible time.
It is advisable to provide heating arrangement to prevent condensation in generator.
1.5.3.5 Generator Protection System and Relay Selection 1.5.3.5.1 Categorisation In view of the economy and plant requirements generator protection for small hydropower stations is categorized a follows:
• Generator size less than 300 kVA • Generator size 300 to 1000 kVA • Generator size 1 MVA to 10 MVA • Generator size above 10 MVA
1.5.3.5.2 Transient overvoltage and surge protection Transient over-voltages and lightning surges are controlled by lightning arrestors. Surge capacitors are provided to restrict rate of rise of surge voltages and their magnitudes. Every generator is provided with a set of lightening arrestors / surge diverter of appropriate rating and generated voltage. 1.5.3.5.3 Minimum protection for a small machine with low resistance grounding are
proposed as follows:
Device No. Description Basic Package
51V Voltage-restrained time over current relay 51GN Neutral ground over current relay Options 27 Under voltage relay 32 Reverse power relay 40 Loss of excitation relay 46 Negative phase sequence relay 49R Stator over temperature relay 50GS Ground sensor over current relay 51VC Voltage controlled over current relay
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64B Generator ground over voltage relay (in place of 51GN where generator is ungrounded)
81 L/H Under / over frequency relay 86G Lockout auxiliary relay 87G Self-balancing current differential relay 12 Over speed relay
7.3.5.4 Minimum protection for a large machine with high resistance grounding
Basic Package 21 Distance 24 Over excitation 27 Under voltage 27TN Third harmonic under voltage 32 Reverse power 40 Loss-of-excitation 46 Current unbalance (negative sequence) 51GN Ground over current (backup to 64G) 51V Voltage-restrained over current 59 Over voltage 60V VT fuse failure detection 64G Stator ground 64F Ground (field)-I 81L/H Under/ Over frequency
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87G Percentage differential 50/27 Accidental energisation protection 95 Trip circuit monitoring 86G Lockout auxiliary relay 12 Over speed relay Options 21G System backup distance relay (in place of 51V) 49R Stator over temperature relay (RTD) 60V2 Voltage ground relay-II 78 Out-off step relay
1.5.3.5.5 Typical schemes With increasing complications in the power system, utility regulations, stress on cost reduction and trend towards automation, generator protection has become a high focus area. State of the art, microcontroller based protection schemes from various manufactures offer a range of solutions to customers to address the basic protection and control requirements depending upon the size and plant requirements.
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1.5.3.5.6 Generators-size less than 300 kVA Normally these generators are controlled by MCCBs, which offer O/C and short circuit protections. It is advisable to have following protections in addition to MCCB. E/F protection (51 N): This will protect the generator from hazardous leakages and ensure operator safety. Many organizations have already made E/F protection as mandatory. Since these units are very remotely located and less manpower is available for operation and maintenance, the system needs more automation and fool proof protections. Therefore, recently several optional protections are also being used for micro/mini units including over speed (12) protections. 1.5.3.5.7 Generators – size 300 to 1000 kVA There are two major differences when compared with the small machines considered above.
• IDMT over current + E/F relay will be required in addition to normal MCCB or ACB releases – since the generator may need shorter trip time for faults in the range 100% to 400% level.
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• By virtue or larger power level, any faults inside the stator or fault between the neutral of the machine and the breaker terminals can reach very high intensity. Such internal faults must be cleared instantaneously. Normal IDMT over current E/F relays are not adequate to monitor this internal fault status-otherwise the machine can circulate very high fault currents resulting in severe damage. A high impedance differential relay scheme, is the best suited for this purpose. If the neutral is formed inside the machine, the differential relay scheme will not be possible. In this case a restricted E/F scheme is the solution. Care should be taken to provide adequate number of CTs.
• Machine of this size are likely to have external controls for frequency and excitation – so that they can be run in parallel with other power sources (other generators on the same bus or the local grid). This necessitates voltage and frequency related protections as well.
1.5.3.5.8 Generators – size 1 MVA to 10 MVA
• Stator side protections o Voltage restrained over current protection (50V/51V)
Normal IDMT O/C will not work here-when an over current fault occurs, due to higher current levels, there would be a drop in terminal voltage. For the same fault impedance, the fault current will reduce (with respect to terminal voltage) to a level below the pickup setting. Consequently normal IDMT may not pick up. It is necessary to have a relay whose pick up setting will automatically reduce in proportion to terminal voltage. Hence the over current protection must be voltage restrained. Two levels of over current protection are required – low set and high set (for short circuit protection).
o Thermal overload (49)
This protection is a must – it monitors the thermal status of machine for currents between 105% to the low set O/C level (Normally 150%)
o Current unbalance (46)
Generators are expected to feed unbalanced loads-whose level has to be monitored. If the unbalance exceeds 20%, it may cause over heating of the windings. This heating will not be detected by the thermal overload relay-since the phase currents will be well within limits. A two level monitoring for unbalance is preferred-first level for alarm and the second level for trip.
o Loss of excitation (40)
When excitation is lost in a running generator, it will draw reactive power from the bus and get over heated. This condition is detected from the stator side CT inputs – by monitoring the internal impedance level & position of the generator.
o Reverse Power (32)
Generators for this size may operate in parallel with other sources, which may cause reverse power flow at certain times.
- During synchronization - PF change due to load/ grid fluctuations - Prime mover failure
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When reverse power happens, the generator along with prime mover will undergo violent mechanical shock – hence reverse power protection is necessary.
o Under Power (37)
It may not be economical to run generators below a certain load level. This protection will monitor the forward power delivered by the machine and give alarm when the level goes below a set point. This may however be optional.
o Under/ over voltage (27/59)
This will protect the machine from abnormal voltage levels, particularly during synchronization and load throw off conditions.
o Under/ over frequency (81)
This will protect the machine from abnormal frequency levels, particularly during synchronization and load throw off conditions. This will also help in load shedding schemes for the generator.
o Breaker failure protection
This protection detects the failure of breaker to open after receipt of trip signal. Another trip contact is generated under breaker fail conditions, with which more drastic measures can be taken, like opening of bus coupler or feeder breaker etc.
o Stator earth fault (64F)
This element tuned to the fundamental frequency can be used for the protection of stator winding from earth fault.
o PT Fuse failure protection
This relay will detect any blowing of PT secondary fuse and give a contact which can be used to lock the under voltage trip.
This protection is very impartment since the machines of this size have to be protected for severe damages that may occur due to internal faults. Considering the large power levels, it is necessary to have a percentage biased, low impedance differential relay. These relays generally have following advantages.
- Percentage biased differential protection with dual slope characteristics - REF protection element (87 N), which will monitor the generator for
internal earth faults - Over current protection, as a back up
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• Rotor side protections Generators of this size will need rotor side protections listed below:
o Diode failure relay
Brushless excitation systems will have rotor mounted diodes, which can become short or open during operation. Diode failure relay will monitor the condition of these diodes, for both open circuit and short, and give alarm
o Rotor excitation current
This is a DC current relay which will monitor the excitation current.
o Rotor excitation voltage This is a DC voltage relay which will monitor rotor voltage The above three protections are normally part of the excitation system of the generator.
o Rotor earth fault
Relay for this protection will monitor the rotor winding status for the earth fault, it will detect the first earth fault occurred in the winding and provide an alarm. The relay employs proven DC rejection method for the detection of E/F. there are other two methods as shown in the diagram for field ground detection.
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EXCITERFIELD
BREAKER
AC
RR
64F
BRUSH
FIELD
C1 C2
Fig. 13 Field ground detection using pilot brushes
1.5.3.5.9 Generator above 10 MVA For large generators above 10 MVA size, the philosophy of main protection and back up protection has to be followed. In addition to the protections listed above following extra protections are to be considered.
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o 100% earth fault protection This will help in sensing earth faults close to neutral. Third harmonic content in the zero sequence voltage will be detected by the replay for the above protection.
o Inadvertent breaker closure
This will avoid closing of generator to bus during process to stop, or when stand still or before synchronism.
o Under impedance
This will be required as a backup protection for the whole system including the generator transformer and the associated transmission line. If the distance relay fails to pick for some reason, this under impedance function will pick up and save the generator.
o Over excitation
This will protection the generator from over fluxing conditions 1.6 GENERATOR CONNECTED IN PARALLEL TO GRID Whenever generators are running parallel to grid, a comprehensive auto synchronizing & Grid islanding scheme will be required. This scheme will help in synchronizing the generator to the bus and opening the incomer breaker of the plant whenever there is a severe grid disturbance, thus protecting the generator from ill effects of disturbed grid.
• Grid disturbances Under-voltage / Over-voltages Under-frequency/Over-frequency Rapid fall/ rise of frequency (df / dt), Grid failure or other faults
Generator may not be able to operate below a certain power-factor. At low power-
factor, reverse reactive power flow may damage the generator.
• Grid fault detection Over current and directional earth fault, Rapid fall/ rise of frequency (df/dt), Vector surge relay,
1.7 GENERATORS CONNECTED IN PARALLEL ON A COMMON BUS
Whenever more than one generator is operating in parallel, it is necessary to see that the plant load is equally shared by the generators in parallel. If there is unequal sharing, there would be sever hunting amongst the generators and eventually this will lead to cascaded tripping of all generators, causing a total black out. Specific load sharing relays are available in the market which provide the most effective, online load sharing system for generators in parallel.
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1.8 PROTECTION GROUPS The protective relays and devices of generator and turbine are proposed to be grouped into following four categories for an orderly shutdown of the affected unit with the remaining generating units and auxiliaries continue to operate. 1.8.1 CONTROLLED ACTION SHUT DOWN Controlled action shutdown will be initiated by any of the following conditions
• Generator thrust bearing pads temperature very high • Generator guide bearing pads temperature very high • Turbine guide bearing pads temperature very high • Governor OPU oil level low stage-II • Governor OPU oil pressure low stage-II
1.8.2 EMERGENCY SHUT DOWN Emergency shutdown will be initiated by any of the following conditions.
• Sped 115% and deflector/ guide vanes/ runner blades apparatus not moved to closing • Deflector etc. fails to close in preset time • Unit over speed (electrical) > 140% • Unit over speed (mechanical)>150% • Stop push button on control panel in control room is pressed
Emergency shutdown system will perform following functions:
• Trip generator breaker • Stop turbine by governor action • Trip generator field circuit breaker • Operate trip alarm in control room • Energizes emergency solenoid valve in governor cubicle to stop the turbine by
bypassing governor • Close main inlet valve
1.8.3 IMMEDIATE ACTION SHUT DOWN Immediate action shut down will be initiated by any of the following conditions
• Generator differential protection operates • Generator stator earth fault protection operates • Generator field failure protection operates • Generator transformer stand by earth fault protection operates • Over current in stator • Over current instantaneous protection in the excitation circuit
The immediate action shut down perform following function
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Trip generator breaker Trip field breaker Initiates controlled action shut down stop turbine by governor action Trip annunciation in control room
1.8.4 ELECTRICAL SHUT DOWN Electrical shutdown system will be initiated by any of the following conditions
• Over current in the excitation circuit • Generator back up protection operates • Generator over voltage protection operates • Excitation failure protection operates • Reverse power protection operates • Generator T/F IDMT over current, over current instantaneous & earth fault protection
operates
Electrical shut down system will perform following functions
• Trip generator breaker • Trip field breaker • Governor brings the unit to spin at no load
1.9 PROTECTION OF POWER TRANSFORMERS Following protections are generally provided on transformers
I. Fuses II. Sudden pressure protection (Buchholtz Relay) III. Oil temperature high IV. Winding temperature high V. Over current/ earth fault VI. Over frequency VII. Differential protection VIII. Restricted earth fault protection IX. Over flux protection (in large grid) X. Over all differential protection (Gen. Trans. Both in large machines) XI. Fire protection system
Fire extinguishers Mulsyfire protection Fire buckets-sand filled
1.10 FIRE PROTECTION SYSTEM For large generators, fire protections system will use CO2 as the quenching medium which will operate automatically. Hot spot/ smoke detectors are provided all around the periphery of generator winding. Bank of CO2 cylinders with control panel etc. are provided common for all the generators. The individual pipes let the CO2 enter in the faulty generator and quench the fire. Generator is isolator from the bus bar and machine stopped. The system is more effective in closed cycle cooling systems of generators.
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ANNEXURE-I
LIST OF GENERATOR PANEL INDICATION AND RELAYS
Sl. No.
Designation Inscription Colours
1 L1 DC Supply on Yellow 2 L2 AC Supply on Red 3 L3 Generator Circuit Breaker Close Red 4 L4 Generator Circuit Breaker Open Green 5 L5 Generator Circuit Breaker Trip Amber 6 L6 Generator Circuit Spring Charge Blue 7 L7 Trip Coil Healthy Yellow 8 L8 DC Supply Failed Red 9 L9 Spare Red 10 R R Phase Bus Healthy Red 11 Y Y Phase Bus Healthy Yellow 12 B B Phase Bus Healthy Blue 13 IPB Immediate Action Trip Push Button Red 14 PB1 Controlled Action Shut Down Push Button Green 15 PB2 Spare Push Button Red 16 TS Temperature Scanner 17 DMF Digital Multi Function Meter 18 H Hooter Black 19 ANN Annunciator Black 20 T Test Push Button Black 21 A Accept Push Button Yellow 22 R Reset Push Button 23 BAPB Bell Accepted Push Button 24 27 Under Voltage Relay 25 32P Reverse Power Relay 26 51V Voltage Controlled Over Current Relay 27 59 Over Voltage Relay 28 60 PT Fuse Failure Relay 29 64S Stator Earth Fault Relay 30 46 Negative Phase Sequence Relay 31 40 Loss of Field Relay 32 95 Trip coil Supervision relay 33 87G Generator Differential Relay 34 52G Generator Circuit Breaker 35 KWTR Kilowatt Transducer 36 BL Electrical Bell 37 86G1 Master Trip Relay 38 86G2 Master Trip Relay 39 86G3 Master Trip Relay 40 86G4 Master Trip Relay 41 Aux Relays As Required
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ANNEXURE-II
LIST OF PROTECTION ELEMENTS IN MICRO PROCESSOR BASED RELAYS
Symbol Description 21 Under Impedance 24 Over Fluxing 26 Field Winding Temp 27 Under Voltage 27NT 100% Stator E/F 32 Reverse Power 38 Bearing Temp 40 Loss of Field 46 Negative Phase Sequence 49 Stator Winding Temp 50BF Breaker Failure 50P Instantaneous Phase Over Current 50N Instantaneous Neutral Over Current 50/27 Unintentional Energisation at Stand Still 51P Time Delayed Phase Over Current 51N Time Delayed Neutral Over Current 51N Voltage Controlled Over Current 59 Over Voltage 59N Residual Over Voltage 64R Restricted E/F 78 Pole Slipping Protection 81 Over/ Under Frequency 87G Generator Differential CTS Current Transformer Supervision VTS Voltage Transformer Supervision
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SECTION II TECHNICAL SPECIFICATIONS FOR CONTROL, PROTECTION & METERING ( MICRO HYDEL UPTO 100 KW)
2.1. Scope The scope includes design, manufacture, shop testing, delivery erection, testing, commissioning and training of purchaser personnel for PLC/ computer based automation system with manual control facility for the operation of power plant from power house. The scope also includes protection, annunciation, synchronization, metering and other components for making the system complete and to ensure a trouble free and safe operation on turnkey basis. Manual control and manual synchronization shall be provided in addition to PLC/computer based auto control and auto synchronization . For Turbine –Generator unit one Panel shall be provided. The Panel shall incorporate components for generator protection, indication & alarm devises and meters for metering various parameters. The requisite functions for ELC can also be incorporated in this control panel. The Air Circuit Breaker for generator may also be incorporated in this panel. 2.2.Applicable Standards (i ) ANSI / IEEE 1010-1987- IEEE Guide for Control of Hydroelectric Power Plants (ii) IS/IEC/ISO Standards mentioned in the text 2.3. Design Criteria The control will have provision for start, stop, manual and auto synchronizing, protection, metering and emergency stop as per enclosed drawing (to be enclosed by Purchaser).
Standard control scheme of turbine suitable for micro hydro plants will be adopted.
PLC/computer based controller system will have a dual power unit. The main power unit will work on 24 V DC and the hot standby power unit will take power from a UPS at 240 V AC.
Automation system shall have capability to provided diagnostic information in the event something fails to operation during the start sequence/running.
All the protective equipment will be housed in the Power Plant main control room. The details of C.T.’s for all the units protection and metering shall be subject to approval by purchaser.
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2.4. PROTECTION AND METERING Electrical control, protection and metering system will be based on state of art technologies. PLC based automation systems for the operation of power plant will be adopted. The complete metering and protection scheme is shown in Drawing (to be enclosed by Purchaser0. This protection scheme is tentative and is for the general guidance of the tenderer and does not restrict the tender to give offer for better scheme.
A. Generator Protections
• Voltage restraint over current (51V) • Stator earth fault relay (64 S) • Over speed electrical/Mech. (12) • Over Voltage Protection (59) • Under voltage protection (27)
Following Mechanical Protections will be provided on Generator
• RTD (PT-100) in stator core and bearing for indication, alarm, recording and shutdown of the unit for stator & bearing temp control
• Over speed for normal and emergency shutdown.
B. Metering System
The power generated shall be metered at generator terminal through metering CT and PT. Following metering instruments shall be provided on relevant panels.
1. kW Meter 2. kWH Meter 3. kV Meter 4. Ampere Meter 5. PF Meter 6. Frequency/Speed Meter 7. Temperature Meter for (To be provided only on generator panel)
a. Stator b. Turbine bearing c. Generator bearing
C. Annunciation System
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A multipoint microprocessor based annunciator with suitable number of ways for projecting visual signals and audible alarm in case of fault shall be provided on the control panels suitably. The annunciator shall be back connected flush mounting, dust tight and tropicalised and shall be complete with audible warning device, and apparatus as required to complete the annunciator system. It shall be suitable for operation on 24 V.D.C. supply.
D. Indication System
The control panel shall incorporate the visual indication such as Breaker on, Breaker off, Breaker Trip, B/F Valve open, B/F Valve close, D.C on, D.C. off etc. The indication lamps should be 24 V D.C. operated, interchangeable and replaceable from the front of the panel.
E. Potential Transformers
The potential transformers to be used for metering & protection circuits shall be epoxy cast resin, class ‘F’ insulation dry type units. The potential transformers shall be protected on primary and secondary side by current limiting fuses. The potential transformers shall confirm to the latest Indian standard. IS-3156 (1992)
F. Current Transformers
The current transformers should be suitable for metering & protection circuits shall be epoxy cast resin, class ‘F’ insulation dry type units. The current transformer will be wound primary or bar primary as the case may be. The current transformers shall confirm to the latest Indian standard. IS–2705 (1992)
G. Surge Arrestors
The L.T surge arrestors shall be provided in the control panel. The L.T. surge arrestors shall confirm to the latest Indian standard.
H. Unit control Board
Following components shall be provided on UCB (the list is tentative). Bidder shall have to provide additional component, if required for proper operation of unit.
i 415 V --- A Circuit Breaker for generator (MCCB with shunt trip may be used.)
1 No.
ii Voltmeter 0 – 500V & Voltmeter S/S 1 No. iii Relays Voltage restraint over current (51V)
Stator earth fault relay (64 S) Over speed electrical/Mech. (12) Over Voltage Protection (59) Under voltage protection (27)
iv Other meters, switches and alarms
1 No. Each
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Ammeter (0-50 A) & Ammeter Selector Switch 1 No. Kilo-Wattmeter ( 0-30 kW) 1 No. Energy Meter (kWH meter), 1 No. Indication Lamps Generator Breaker OFF/ON/TRIP 3 No. Indication Lamps D.C.ON / OFF ( if provided) 2 Nos. Indication Lamps for B/F Valve open/close 2 Nos. Potential Transformer for protection, metering and AVR 3 Nos. Current Transformers for Protection & Metering 7 Nos. Frequency meter 45-50-45 HZ 1 No. Auto manual change over switch Power Factor meter 1 No. Emergency Push Button 1 No. Annunciation Window for faults & Buzzer/alarm 1 No. Electronic load controller.
1No.
2.5
Tests Routine and type test certificate of CTs, PTs, LAs, Relays, Metering instruments as per IS shall be submitted for approval of the purchaser.
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SECTION - III
TECHNICAL SPECIFICATIONS CONTROL, PROTECTION AND METERING
(FOR SHP ABOVE 100KW TO 1000KW) 3.1 SCOPE
The scope includes design, manufacture, shop testing, delivery, erection, testing, commissioning and training of purchasers’ personnel for computer based automation systems for the operation of power plant from powerhouse. The scope also includes protection, annunciation and synchronization, metering and other components for making the system complete and to ensure a trouble free and safe operation on turn key basis. The power station will comprise the following major components:
i. –x--- kW Synchronous Generating units, Francis Turbine being the
prime mover and synchronized at 415 V, Static excitation and governing systems being digital.
ii. -- Nos. --- kVA 0.415/11 kV Ynd11 50 Hz 3 phase transformers. iii. -- Nos. 11 kV feeders controlled by 11 kV vacuum circuit breakers. iv. 1 No. --- kVA 11KV/0.415 kV Station Transformer and --- kW Diesel
set for station supplies
Following drawings show tentatively the main scheme (to be supplied by the
Purchaser) :
Single Line Diagram
Metering and Protection System
3.2 CONTROL EQUIPMENT
The control equipment shall comprise of the following:
Generating Units Control
i. Local/Manual control of generating units from hard wired control panels. ii. Automatic control of generating units from unit control boards by PLC based
unit controllers. 3.3 SYNCHRONIZATION
Manual synchronization shall be provided in addition to computer based auto-synchronization with an appropriate change-over switch on the control panel. A check synchronizing relay will be provided.
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3.4 ALARM AND ANNUNCIATION
Window annunciation shall be provided on the unit control board and the same shall be complete with audio and video alarm system. The system shall be designed to have low DC power consumption. 3.5 METERING
i. All panel meters shall be digital with at least 2 cm digit size, at least three-and-a-half digit LED display and accuracy class of 1.0 or better.
ii. Energy metering shall be provided on the 11 kV feeders and generators with electronic energy meter of an accuracy class of 1.0 or better.
iii. Digital Multi-functions Meter alongwith analogue type three ammeter and voltmeter with selector switch shall be required for each generator circuit.
3.6 PROTECTION RELAYS
i. Each generator shall be provided with static digital numeric type of relays for the protection system.
ii. Digital relays shall be provided for the protection of 11 kV feeders and --- kVA 415 V/11 kV Generator Transformers.
3.7 UNIT CONTROL BOARD
The Unit control board for each unit fitted with necessary devices and appropriately wired using standard accessories shall be provided. Instruments required for turbine control, monitoring and protections shall be provided by turbine manufacturer for which close liason shall be required between different manufactures.
3.8 COMPLETENESS
All such systems/equipment/components/works which are necessary for the completeness of the system but not mentioned explicitly shall also be a part of the scope of the contractor.
3.9 SPARE PARTS & TOOLS
The contractor shall ensure supply of the spares for all the offered equipment/components (at least one module of every type) for use for 5 years and any special tools & plants, spanners etc. required for site assembly, erection, testing, commissioning, operation & maintenance of the equipment.
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3.10 DOCUMENTATION
The contractor shall provide all necessary drawings, diagrams and documentation of
equipment and software. The documentation in original shall also include six hard copies and
one soft copy of the following:
a. Hardware:
The necessary user, reference and service manuals along with the technical
specifications for all the hardware systems/sub-systems shall be supplied by the contractor.
The extent of documentation to be furnished shall be to the satisfaction of the Purchaser.
b. Software:
User and reference manuals related to complete software shall be supplied by the
contractor. The extent of the documentation to be furnished shall be to the satisfaction of the
Purchaser.
3.11 STANDARDS
Standard and codes to which the equipment must conform are given below.
IEEE Std 1249 – 1996 Guide for computer based control of hydroelectric plant automation
IEEE Std 1020 – 1988 Guide for control of small hydro plant IEEE Std1010 – 1987 Guide for Control of Hydro Electric
Power Plant IEEE 2519 Power Quality
IEC 687 Alternating current static watt-hour meters for active energy
IEC 225 Electric relays
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IEC 68 Environmental testing
IEC 60255-21-1 Vibration
IEC 60255-21-2 National Electrical Code
IEC 60255-1-3 Earthquake
IEC 801-2/4 Static discharge test
IEC 801-3/3 Electromagnetic fields
IEC 801-4/4 Transient fast burst test
IEC 801-5 Surge withstand test
IEC 801-3 Dielectric tests
EN 5501/COSPR11 Emission, terminal disturbance
EN 55011/CISPR11 Emission, radiation disturbance
IEC 62000-4-6 Electromagnetic fields
IEC 61000-4-3
IEC 61000-4-4 Fast transients/Bursts
IEC 61000-4-5 Surge voltage
IEC 61000-4-11 Voltage dips
IEC 60255-22-1 1MHz Burst disturbance
IEC 68-2-1 & 68-2-2 Temperature IEC 68-2-30 Humidity IEC 68-2-6 Vibration of Unpackaged Products IEC 68-2-27 Shock of Unpackaged Products ASTM D999-75 Vibration of Packaged products ASTM D775-80 Shock of Packaged products
IEC 1000-4-2 Electrostatic Discharge Immunity IEC 1000-4-3 Radiated Electromagnetic Immunity IEC 1000-4-5 Surge Transient Immunity IEC 1000-4-4 Electrical Fast Transient/Burst Immunity IEC 1000-4-6 Conducted Electromagnetic Immunity CISPR 11 (EN55011) Radiated Emissions
UL94V Flammability and Resistance to Electrical Ignition
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3.12 FUNCTIONAL REQUIREMENTS 3.12.1 Automation System and Control Options
Computer-based automation systems shall permit operation of the power plant from local (Machine hall). Local manual control shall also be provided in the equipment as a backup.
3.13 UNIT CONTROLLERS
For each generating unit, there will be an independent PLC based unit controller. Back up manual control shall also be provided for each unit.
Each PLC/computer based controller system will have a dual power unit. The main power unit will work on 24 V d.c. and the hot-standby power unit will take power from a UPS at 240 V a.c.
3.13.1 Unit Control
3.13.1.1 Control Functions
The unit controllers will control the generating units individually and shall perform following functions:
i. Automatic start and synchronization ii. Automatic stop iii. Control action shut down iv. Emergency shut down v. Governor control vi. Excitation control (AVR and APFC) vii. Sequence control viii. Alarm and annunciation ix. Input from transducers & sensors x. Active power control
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3.13.1.2 Auto Start/Stop
The equipment controlled and monitored during the start/stop sequence will generally include the following:
a. Main inlet valve; b. Governor hydraulic oil system; (If provided) c. Guide Vane limit positions; d. Guide Vane positions; e. Cooling water system; (If provided) f. Excitation equipment; g. Unit speed; h. Protective relaying status; i. Unit alarms; j. Unit breaker status;
3.13.1.3 Diagnostic Information
Automation system shall have capability to provide diagnostic information in the event something fails to operate during the start sequence/running. 3.13.1.4 Control Scheme Of Turbine
Standard control scheme of turbine suitable for mini hydro plants will be adopted.
3.13.1.5 Back up Control
Back up control including black start should be provided as per IEEE-1249. The black start shall be accomplished by providing manual pumping of the oil pressure system.
3.13.1.7 Auxiliary Power
The auxiliary power at 415 V shall be taken from the 415 V generator bus and 15 KW 3φ diesel generating set as shown in drawing No. -----.
3.13.1.7 D.C. Supply
The D.C. power at 24 V for all controls, circuit breakers, relays and meters etc. shall be obtained from one set of station battery. The battery bank shall have 200 AH capacity tentatively and shall be float and boost charged from rectifier units. Calculations for the capacity of batteries shall be submitted by the bidder for the consideration of the purchaser. 3.14 PROTECTION AND METERING DETAILS
3.14.1 Protection and Metering Scheme
Requirements of metering and protection/scheme and the function performed by various relays is indicated in tentative drawing for Protection and Metering System:
All the protective relays will be housed on the unit control board.
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The final drawings for the protection & metering shall be submitted by the contractor and will be subject to the approval by the Purchaser.
3.14.2 CTs/VTs
All current and voltage transformers required for protection system of the unit shall have adequate VA burdens, knee point voltage, saturation factor and characteristics suitable for the application, and shall be subject to approval of the Owner. 3.14.3 Special Features of Proposed Protection System
i. The protection system shall be built on latest technology and the bidder has to guarantee for supply of spares for at least 5 years. Moreover, the bidder should have full range of manufacture of the system offered.
ii. Wide setting ranges with fine setting steps for each protection shall be
available. iii. The offered system shall have proven record of satisfactory performance for
at least 2 years and in two power stations. Necessary certificates to this effect shall be a part of the offer.
iv. The protective relays shall preferably be housed in draw out type of cases with
tropical finish. v. Common tripping relays (each for similar functions) will be provided with
lock-out facilities. All these relays shall have potential free contacts for trip and alarm purposes and externally hand reset type of flag indicators.
vi. The relays shall be static/digital/numeric type. 3.14.4 Generator Protection(electrical) 3.14.4.1 Following generator protection relays shall be provided for each generator:
i. Differential Relays (87) ii. IDMT over current and instanteous over current in stator (50/51) iii. Stator earth fault protection (64G) iv. Phase unbalance Relay (46) v. Field Failure Relay (40) vi. Reverse Power Relay (32) vii. Over voltage protection (59) viii. Under voltage (27) ix. Over Speed (12)
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3.14.5 Generator Protection(mechanical) 3.14.5.1 Following mechanical protections shall be provided for each unit.
a. Resistance temperature detectors (Pt-100) in stator core and in the
bearings for indication, alarm and recording. RTD’s are to be provided by Generator Suppliers (optional, if available in standard generator).
b. Turbine and generator bearing, metal and oil temperatures – alarm/shutdown (optional, if available in standard generator).
c. Governor oil pressure low to block starting and very low for emergency tripping (If Governor oil pressure unit is provided for governing system)
d. Over speed for normal and emergency shutdown depending upon its extent.
3.14.6 Generator Transformer
Following static relays shall be provided for Generator Transformer Protection.
i. Over current protection with high set instantaneous on 11 kV side (50/51).
ii. Stand by earth fault protection (64S) on 11 kV side. iii. Oil temperature high – alarm/trip (OT). iv. Winding temperature high- alarm/trip (WT) v. Bucholz relay – alarm/trip (B).
3.14.7 11 kV Feeder Protection
Static over current and earth fault relay with high set unit shall be provided (50/51,64) alongwith over/under frequency relay (81) for feeders protection. 3.14.7 Station Transformer Over current/earth fault protection for this transformer shall be provided on generator bus side. It is presumed that diesel generator protection shall be provided on control panel of the set. 3.15 METERING SYSTEM
The power generated shall be metered at generator terminal through metering CTs and PT. The power transferred to 11 kV feeder shall also be metered through CTs and PT.
Following metering instruments shall be provided on generator control panel and 11
kV vacuum circuit breaker panel for feeders. Digital Multi-functions Meters alongwith analogue type ammeters and voltmeter shall be provided. 3.15.1 Generator Control Panels
1. kW meter 2. kWh meter 3. Voltmeter with selector switch 4. Ampere meters separate for each phase 5. Power factor meter 6. Frequency meter 7. Temperature meter with selector switch
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3.15.2 11 kV Feeder Panels
1. kW meter 2. kWh meter 3. Voltmeter with selector switch 4. Ampere meters with selector switch 5. Power factor meter 6. Frequency meter
3.15.3 Generator Transformer Panel
1. Voltmeter with selector switch 2. Ampere meters with selector switch
3.15.4 Station Transformer Panel
1. kWh meter 2. Voltmeter with selector switch 3. Ampere meters with selector switch
3.16 UNIT CONTROL BOARD/CONTROL PANEL
3.16.1 Constructional Features
i. All panels shall be of standard construction, dimensions, materials and sheet
thickness of not less than 2.50 mm. ii. Panels shall be of simplex types (devices mounted on the front panel and
double door on the back side). iii. Panels shall be painted by dry electro-static powder coating process. iv. All accessories mounted on the front panel shall be flush mounting type. v. Each panel will have mimic diagram painted or embossed on its front. vi. Each panel will have arrangements for internal lighting and heating. vii. The wires and wiring accessories, terminations etc. shall be as per relevant
Indian Standards. The unit control board for each generating unit shall accommodate necessary relays,
measuring instruments, indicators, control unit, control switches, annunciator, temperature scanner etc. for the operation of the generating units. The generating units shall be controlled from this control panel during starting, stopping and normal running in manual and auto modes. 3.17 SYNCHRONIZING PANEL
Synchronizing equipment with check feature shall be provided for synchronization of the generating units at the 415 V bus bars and shall comprise of a centrally positioned panel. All the indicating meters with associated switches and fuses should be mounted on the upper half of Central panel so that it is easily visible to the operator.
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Synchronising switch shall be mounted near each generator circuit breaker control
switch on the respective unit control panel. Contacts provided in each switch shall be connected in the closing circuit of the respective breaker so that the breaker can not be closed until the switch is turned to the “Synchronising” position. Switches shall be arranged so that the handle will be locked only in the ‘OFF’ position and check synchronizing relay shall be provided, so that the breaker could be closed only when voltage, frequency and phases are properly matched.
Provision for closing the breaker without synchronising check should also be made
with the check synchronising switch in OFF position. All necessary interlocks, auxiliary potential transformers, auxiliary relays, wiring of
the synchronizing bus inside the control panel, fuses, clamps and other accessories for satisfactory synchronizing operation shall be provided by the contractor. The synchronizing scheme is subject to purchaser’s approval.
Computer based auto synchronization shall also be provided in addition to manual synchronization with an appropriate change over switch on the control panel.
3.18 ANNUNCIATION SYSTEM
A multipoint microprocessor based annunciator with suitable number of ways for projecting visual signals and audible alarm in case of fault shall be provided on the control panels suitably. The annunciator shall be back connected flush mounting, dust tight and tropicalised and shall be complete with audible warning device, and apparatus as required to complete the annunciator system. It shall be suitable for operation on 24 V.D.C. supply.
The operation of the annunciator system shall be as follows: -
(i) When an external initiating contact is closed, the audible warning shall sound continuously and the appropriate facia shall be illuminated by flashing light.
(ii) An “acknowledge” push button shall be provided on the annunciator unit which when pressed shall stop the audible signal and cause the facia to remain illuminated steadily.
(iii) The annunciator facia illumination shall normally be designed to retain the indication after the re-opening of the initiating contact. A “reset” push buttom shall restore the annunciator to the normal condition.
(iv) A “test” button shall be provided close to the “acknowledge” and “reset” buttons to illuminate all the facias on the associated display unit for as long as the test button is held in pressed condition.
(v) In case there is a second fault on a system when the first is already being shown by the facia, the annunicator shall show the second fault also even when the first is existing on facia.
The following facility shall be provided with each of the annunciator points: -
It shall be possible to use “Normally open” type contacts as initiating contacts for the
annunciator. It shall also be possible to use a few “Normally closed” type of initiating contacts, if required.
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It will be the responsibility of the contractor to provide all the alarms and
annunciations required for the safe and efficient operation of the power station.
An A.C. operated relay with A.C. buzzer and A.C. indicating lamp with reset push button shall be supplied for annunication of D.C. supply failure.
Alarm horns, flicker light relays, necessary hardware and any other auxiliary equipment required to complete the annunciation system shall be provided. 3.19 FACTORY TESTING 3.19.1 Equipment Tests
Each individual equipment shall be routine tested as per IEC/IS at the work’s of supplier in presence of Owner.
3.19.2 System Tests
The contractor shall organize and execute a complete factory test of the system. The system shall be erected in his workshop in the engineered configuration and shall be tested for the following:
i. Operation requirements ii. Operating characteristics iii. Response times iv. Software functions used in PLC based unit controller. v. Deficiencies
Various process signals shall be simulated for carrying out above system tests. The Supplier shall submit routine test reports of each equipment and the total system. 3.20 SITE TESTING
The contractor shall carryout tests at site as per relevant IEC/IS standards as follows in the presence of and to the entire satisfaction of the owner:
i. Calibration checks (on sample basis) on all factory calibrated meters and transducers.
ii. Acceptance tests on all other devices fitted on the unit control boards and earlier tested in factory.
iii. IR tests on panels. iv. Continuing and IR tests on external cablings. v. Calibration checks/acceptance tests on all devices and equipment connected to the
unit control boards. vi. Functional checks on each equipment/object controlled from unit controllers with
control circuits de-energised. vii. Functional checks on unit controllers with power circuits de-energised. viii. Verification of all manual control functions from unit control board. ix. Verification of all control sequences from unit controllers with power and control
circuits energised. x. Watch up each generating unit and perform all start/stop sequences on it.
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3.21 DRAWINGS
(i) The tenderer shall submit three sets of drawings of the equipment offered along with illustrated and descriptive literature for scrutiny and record.
(ii) Certified copies of type test certificates. (iii) Detailed dimensions drawings along with mounting details.
3.22 SPARE PARTS & TOOLS
The tenderer shall supply spares required for maintenance for a period of five years and special tools required for site assembly, erection, testing and commissioning, operation and maintenance.
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SECTION -IV
TECHNICAL SPECIFICATION FOR
CONTROL PROTECTION, METERING, SUPERVISORY CONTROL AND DATA AQUISITION SYSTEM (SCADA)
(FOR SHP ABOVE 1 MW TO 5 MW CAPACITY)
4.0 SCOPE
The Contractor shall design, fabricate, assemble, test at manufacturers works, supply, deliver, erect, test at site, Commission and train owner’s operating personnel for the Control, Protection and Metering Equipment and System for power generation, transformation and transmission and comprising of following.
A Manual (conventional) Control and Protection System. (i) Unit control, metering and protection relay panels (For units 1 & 2). (ii) 33 kV Feeders and bus sectionaliser C.B. control, metering and protective
relay panels. B Supervisory Control and Data Acquisition System
4.1 APPLICABLE STANDARD
1. ANS/IEEE 1020 – 1987 – IEEE Guide for Control of Small Hydroelectric Power Plants 2. IS/IEC/ISO Standard Mentioned in Text 4.2 CONTROL AND MONITORING SYSTEM General Considerations
Considerations involved in providing control and monitoring systems for the power plant and the switchyard are as follows:
a) Main Single Line Diagram is shown in drawing (to be supplied by Purchaser); Metering and Relaying as proposed is shown in drawings(to be supplied by Purchaser).
b) The power house is proposed to be controlled supervisory control from centralised control room Accordingly provision is to be made for manual and automatic control for unit starting, unit stopping and running control and data acquisition at the power house in centralized control room.
c) Control of unit operation is detailed in para 1.2.1. d) Dependable digital controls for system control with conventional manual
control as backup are proposed.
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e) The turbines, generators, transformer and other equipment proposed for the unit will be provided with necessary sensors and actuators. Control shall meet the operational requirement of Butterfly valve which is closed by weight under emergency.
f) The generators are proposed to be provided with static excitation system. g) Two number 3.3/33 kV unit transformers of -- MVA capacity each are
proposed to step up the generated power to 33 kV. j) A single 33 kV bus is proposed.
The scheme will be designed in accordance with ANS/IEEE – 1020 and will be subject to approval by owner.
4.2.1 CONTROL OF UNIT OPERATION
The generation units of power plant are proposed to be controlled by push button from the main centralized control Board in the power Station with provision of control from SCADA system in the control room. Suitable interlocks shall be provided to safe guard the machine against inadvertant faulty operations and to ensure correct operation of all sequences when starting the machine from the power stations or from remote station.
Normal Start ing
The normal starting and stopping of each unit is proposed effected through local remote switches to energize a sequence controller installed on the control panel of each unit.
The master controller switch in the first step of its sequence, shall open-turbine inlet valve and start unit auxiliaries.
In the second step of the sequence the turbine shall be started and field breaker is closed.
Synchronization shall be by auto-synchronization as part of SCADA after second step. Provision of standby manual synchronization in the third step is also required.
Loading of generating unit shall be in the fourth by remote control of the limiter motor and speed level motor.
Normal stopping of the unit is similarly achieved in steps.
Unit Stopping on Emergency
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Automatic protective devices shall be provided to detect failures in normal operating conditions of the various equipments and secure an emergency stop of the unit whenever necessary and actuate alarms.
It is tentatively proposed that emergency stopping of the units should occur in the following cases:-
a). Electrical protection operation
b). Mechanical protection operation.
c). Turbine speed 115%
d). Turbine over speed 130% (tentative figure)
Emergency closing of turbine inlet valves is proposed in the following case:
a). Turbine speed 140% (tentative figure)
Hydraulic Control
It is proposed to provide a system of water level controls based the for transmission of storage reservoir laves to the power plant and actuate alarms/shutdown whenever the levels goes beyond abnormal values and trail-race level by means of sensor installed in tailrace well for actuating runner blade angle.
4.3 CONTROL AND MONITORING OF PLANT EQUIPMENT 4.3.1 General
The control system shall receive input signals from main equipment such as the turbine or the generator, and from various other equipment, such as the governor, exciter, etc. Status inputs shall be obtained from control switches, level and function switches indicative of pressure, position etc, throughout the plant. The proper combination of these inputs to the control system logic will provide outputs to the governor, the exciter, and other equipment to start or shutdown the unit. Any abnormalities in the inputs must prevent the unit’s startup, or if already on-line, provide an alarm or initiate its shutdown, depending upon the magnitude of abnormality. The unit control boards should be designed to perform the following functions: (i) Information receipt and monitoring (ii) Start/stop sequencing control (iii) Annunciation of alarm conditions
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(iv) Temperature information monitoring (v) Metering and instrumentation signals display (vi) Event recording, when required (vii) Synchronizing and connecting the unit to the system The unit control board is the central control means and communicates with the main and associated equipment through hard wire or multiplexing.
4.3.1.1 33 kV line Control
Manual remote control of the 33 kV Vaccum/ SF6 breaker is proposed in the powerhouse in the centralized control room.
4.3.1.2 Station Service System
The unit auxiliaries are proposed to be provided automatic control to suit the unit control as proposed for manual/supervisory control room centralized control room.
4.3.1.3 Annunciation
Annunciation system is proposed to be designed for control of the unit from the powerhouse in centralized control. The normal annunciators consisting of indicating lamp and relay assembly is proposed to be provided on the unit control boards in the powerhouse.
Data logging – Data will be stored in hard disc and printed every half an hour for which printer will be provide at centralized control room. 4.3.1.4 Auxiliaries Control
Centralized controls of the power distribution and control boards is proposed for attended automatic operation. Automatic switching of selected standby and emergency auxiliaries on failure of running auxiliaries is proposed. Automatic change over of entire unit auxiliaries to alternate source of supply is also proposed.
4.3.1.5 Switchgear and Motors
Air break switchgear is proposed to reduce fire hazard. The opening/closing time of switchgear may not exceed 8 cycles so that stalling of motors on change over does not take place. All motors will be direct on line starting and are therefore high starting torque.
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4.3.2 Control and Status Data
Control and status data to be transmitted from various equipment to Unit Control Board and from Unit Control Board to the equipment etc is detailed below. This is tentative and may be increased or decreased as required with owner’s approval.
Information and control signals will be needed between the control board and each of the following:
1 Turbine Table – 1.1 to 1.3 2 Turbine speed governor Table – 2.1 to 2.3 3 Generator Table – 3.1 to 3.4 4 Generator excitation system Table – 4.1 to 4.3 5 Unit transformer Table – 5.1 to 5.2 6 Circuit breaker and switches Table – 6.1 to 6.2 7 Intake valve and draft tube gate Table - 6.3 8 U/S and D/S water level
Additionally, control signal shall also be from Auxiliary equipment, Fire Protection, Auxiliary AC Power Supply, DC Power supply, Service Water, Service Air shall be provided as per IEEE – 1020.
These equipment blocks represent auxiliary service equipment needed for the proper operation of the generating plant. Abnormal conditions of this equipment will be alarmed.
Table- 1.1 - Control and Status Data Transmitted form Turbine to Unit Control Switchboard
SIGNAL DESCRIPTION TYPE NOTES
38TG Turbine guide bearing temperature
T,A,P,I Temperature detectors, Provision for mounting two sensors in bearing shell.
38QTG Turbine guide bearing oil temperature
T,A,P,I Temperature detector in bearing oil reservoir.
71QTGH Turbine guide bearing oil level high
A Sensor in bearing oil reservoir, with direct reading visual indicator
71QTGL Turbine guide bearing oil level low
A Sensor in bearing oil reservoir, with direct reading visual indicator
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33SP
Wicked gate shear pin failure
A Shear pin failure while closing wicket gates due to obstruction
80WB Bearing cooling water low flow
A Pump failure, obstructed piping or pipe rupture.
71WTH
Turbine pit water high level A, C
Senses excessive water level in turbine pit due to plugged drains or major seal failure. One contact operates submersible pump.
SCWP
Water pressure in Intake P, I
Direct reading on transducer operated gauge. Unit startup interlock, shutdown if loss of pressure in running unit
DTWP Draft tube water pressure-vaccum
I
Direct reading on transducer operated gauge
48TG
Turbine greasing system failure ( if greasing system provided )
A Alarm if lubrication cycle not completed
74TG Turbine greasing system low voltage( if greasing system provided )
A
Detects failure of power supply to solenoid valve used to control greasing cycle.
Wicket Gate Servomotor Position
C
Feedback to the governor control system.
Runner Blade Servomotor Position
C
Feedback to the governor control system.
TYPE C = Control
P = Protection Trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
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Table- 1.2 - Control and Status Data Transmitted from Unit Control Switchboard to Turbine
SIGNAL DESCRIPTION TYPE NOTES
1GS Turbine grease system Start/Stop (if greasing system provided)
C Enables grease system when uni t is running.
1TL Turbine lube oi l system start /stop
C Enable turbine lubr icat ion pr ior to uni t
run. Type
C = Control
P = Protection Trip A = Annunciat ion/Event Recording
T = Temperature Monitoring I = Indication (analog, digital, status lamps)
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Table‐1.3 ‐ Operating Power, Air and Water from Service Equipment to Turbine DESCRIPTION
TYPE NOTES
Power supply for control and protection devices
DC
Power supply for turbine pit water pump AC
Air supply for shaft maintenance seal. A
Water supply for bearing oil coolers and turbines seals
W
Power supply for Lubricating oil system for bearing
AC May be alternately fed from DC.
Type AC = AC Power DC = DC Power A = Air W = Water Table 2.1 – Control and Status Data Transmitted from Governor to Unit Control
Switchboard
Signal Description Type Notes
N Speed indication I Methods of developing the speed signal include the following :
- Hall-effect, eddy current, magnetic sensors operated in conjunction with toothed wheels or other devices directly connected to the generator shaft (speed signal generator – SSG)
- Voltage transformers connected to the generator output leads must be capable of operating at very low residual voltages in absence of field excitation
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12-X
Over-speed C, P Over-Speed Switch should be actuated mechanically by means of a centrifugal device mounted on the turbine shaft.
12-X1 13-X 14-X
Over-speed, Synchronous speed and under speed switches
C, P Electrically actuated speed relays by comparing the speed signal to a reference signal
65SF Speed signal failure
A,C,P Loss of speed signal may initiate control action i.e. shutdown of the unit and annunciation.
39C Creep detector operation
A,C Control action upon detection of shaft movement after shutdown may include any or all of the following :
- Start thrust/guide bearing HP oil pump - Release brakes - Drop intake gates - Alarm - Start turbine guide bearing oil pump
65Ss Start/stop solenoid
auxiliary contacts or gate limiter limit switches
C,I Provides information of starting /stopping process.
65SNL Speed-no-load solenoid aux. contacts or gate position
C,I Provides confirmation of 65SNL operation. Used to seal in remote controls and provide remote indication.
WG Wicket gate position indication
C, I Typically derived from potentiometer or LVDT coupled to restoring connection from wicket gate servomotor.
33WG Wicket gate position switches
C,P,I Typical uses of gate position switches for control and indication:
- Generator brake application (that is, apply brakes at low speed if gates at 0%)
- Turbine gate lock (apply at 0% gate position)
- Trip generator breaker as gates pass through speed-no-load position (auto-stop, protective shutdowns without overspeed)
- Incomplete stop detection - Unit running detection - Initiate time delay for stopping auxiliaries - Reenergize starting relays to provide
restart after momentary loss of power
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71 QP Governor Oil Pressure Unit – oil level switches in Pressure Vessel
A, P Alarms for high, low and extreme low levels. Shutdown for extreme low level, air admission for high level.
63Q Governor Oil Pressure Unit -pressure switches on Pressure Vessel
A, P Pump control, alarms for low and extreme low pressures, shutdown for extreme low pressure.
71 QS Governor Oil Pressure Unit –level switches for oil level in sump tank
A Alarms for high and low oil levels.
26QS Governor Oil Pressure Unit – sump tank oil temperature high
A Indicative of excessive governor action.
6Q Governor Oil Pressure Unit – standby pump operation
A Indicative of excessive governor action or pump failure
27PS Governor power supply failure
A,C,P Indicates failure of input AC or DC power or failure of regulated DC power supplies. May result in unit shutdown depending upon level of power supply redundancy.
63AB Generator air brakes applied
C,I Indication and auto-start interlock.
63ABS Generator air brake supply pressure low
A
33WGL Wicket gate automatic lock applied/released
C, I Indicates status of the gate lock (applied on shutdown when gates at 0%)
65WGLF Wicket gate automatic lock failure
A Indicates that the gate lock has not been fully applied on shutdown
65M/LS Manual control indication
I Provides remote indication that the governor is in manual control at the governor cubicle
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C = Control P = Protection trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
Table 2.2 – Control and Status Data Transmitted from Unit Control Switchboard to Governor
Signal Description Type Notes
39 Creep detector
enable C Enables rotor creep detector after a fixed time
following application of brakes on shutdown
15FR, 15FL
Speed reference raise /lower commands
C Typically relay or switch contact closures. If power reference also provided, speed raise/lower operable only off-line. Some installations may utilize input reference analog or digital signal rather than raise / lower commands
65PR, 65PL
Power reference raise /lower commands
C Typically relay contact closures when unit on –line. Some installations may utilize input reference analog or digital signal rather than raise/ lower commands
65GLR, Gate limit raise/lower commands
C Typically relay contact closures, route to reversing drive motor. Primary function of the gate limit (GL) is to limit the maximum opening of the wicket gates under operator control to prevent overloading the unit at the prevailing head. Other control and protection applications include:
- Pre- positioning GL to 0%prior to starting to permit controlled opening of the gates upon energization of the start / stop solenoid 65SS
- Raising GL to turbine breakaway gate position after energization of 65SS
- Rapid unloading of the machine during certain stop and protection shutdown sequences
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3SS On-off command to start/stop solenoid 65SS or gate limiter motor
C,P The start/stop solenoid 65SS typically operates as follows :
- Energized to allow wicket gates to open and close under control of the electric governor, gate limit or manual gate control, that is, “energized to start and run”
- De-energized to initiate complete closure of the wicket gates at maximum rate and block subsequent opening of the gates, i.e. “de-energized to stop”
Typical functions that will block start and/or initiate stop are
- Unit protection operation (includes all electrical and mechanical fault detectors that initiate shutdown of the unit)
- Operator-initiated stop - Generator thrust bearing high pressure oil
pump failed to achieve full pressure - Turbine shaft maintenance seal on or low
gland water flow - Generator brake shoes not cleared or brake
air pressure not off, or both - Intake gate not fully open - Generator and turbine bearing cooling water
not available - Wicket gate lock not released
3SNL On/off command to partial shutdown (speed-no-load) solenoid
C,P The partial shutdown solenoid 65SNL (if used) is typically de-energized to limit the opening of the wicket gates, or return them, to a position slightly above the speed-no-load position and is controlled as follows :
- Energized when unit circuit breaker closes to allow generator to be loaded
- De-energized whenever unit circuit breaker trips to restore unit to near rated speed; provides backup to the electric governor
- De-energized to unload the unit for certain protection operations (that is over speed to 112% during opening of unit circuit breaker)
V, I Generator
voltage and current
C Inputs to power transducer (for governors utilizing power feedback rather than gate feedback)
52 Unit on-line C Generator circuit breaker auxiliary contact. Used to switch between on-line and off-line gains in compensation circuits (PID) and to switch between
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speed and power references
3AB Generator air brakes on/off command
C Air brakes automatically applied on shutdown if wicket gates close and speed below a predetermined level
71NH Level difference between headwater and tailwater
C Used for optimum turbine blade positioning and optimum gate position/ power generation.
Type C = Control P = Protection Trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication analog, digital, status lamps)
Table 2.3 – Operating Power, Air and Water from Service Equipment to Governor
Description Type
Notes
Power supply for DC control DC One or more separate supplies depending on power distribution arrangement
Power supply for Oil Pressure Unit pumps
AC One or more separate supplies depending on number of pumps and required redundancy.
Alternate supply for governor power supplies
AC
Air supply for generator air brakes
A
Air supply for Oil Pressure Unit
A
Cooling water for Oil Pressure Unit oil sump
W (Optional)
Type
AC = AC Power DC = DC Power
A = Air W = Water
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Table 3.1 – Control and status data Transmitted from Generator to unit control
Switchboard
SIGNAL DESCRIPTION TYPE NOTES 26GS 38THT 38GT 38QB 26GF 71QBH 71QBL
Stator winding temperature Thrust bearing temperature Guide bearing temperature. Bearing oil temperature Generator field temperature. Bearing oil level high Bearing oil level low
T, A, P T, A, P T, A, P T, A, P T, A, P A A
Temperature detectors (typically 12) embedded in stator winding accordance with ANSI C50. 10-1977 (1). Two hottest RTDs connected to thermal overload relay 49G.
Temperature detectors embedded in wells in the shoes or segments with provision for interchanging sensors between segments. Temperature detectors. Provision for mounting sensors in all segments. Temperature detectors in bearing oil reservoir. Temperature monitoring system for continuously monitoring field temperature. One sensor for oil reservoir, equipped with direct reading visual indicator One sensor for each separate oil reservoir, equipped with direct reading visual indicator.
33AB CT-G
Air brake position indication Neutral end and terminal end current transformers
C, I P, I
Start interlock indicating all brake shoes have cleared runner plate. Furnished in quantities and ratings compatible with the metering and primary/standby protection requirements.
TYPE
C = Control P = Protection trip A = Annunciation/Event Recording
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T = Temperature Monitoring I = Indication (analog, digital, status lamps)
Table 3.2 – Control and status data Transmitted from Generator to unit control
Switchboard SIGNAL
DESCRIPTION TYPE NOTES
2THS 1GL
Thrust bearing high pressure oil pump start/ stop command. Generator lube oil system start/stop command.
C C
Start pump prior to starting unit. Confirmation of pump starting via63QTH (Table 3A-1) Enables generator lubrication prior to unit run. When forced air cooling is used for the generator. Turned off when unit is on-line.
TYPE C = Control P = Protection trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
Table 3.3 – Operating Power, Air and Water from Service Equipment to Generator
DESCRIPTION TYPE NOTES
Air supply for brakes and rotor jacking system Water supply for fire extinguishing system Power supply for generator housing space heaters. Power supply for generator lube oil system.
A W AC AC
Control valve may be located in governor cubicle/ generator brake panel. May also be atomized. Thermostatically controlled, for reducing condensation on windings when generator is shut down. May be fed alternatively from DC source.
TYPE C = Control
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P = Protection trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication (analog, digital, status lamps) Table 3.4 – Control and Status Data Transmitted from Generator Terminal Equipment to Unit Control Switchboard
Signal
Description Type Notes
CT Current signal for relaying and
metering
VT Voltage signal for relaying and
metering
A Current indication I
F Frequency indication I
V Voltage indication I
W/VAR Metering I,A Analog signals for
indication and/or recording.
AVR Voltage signal for automatic voltage regulator (AVR)
C Analog signal from a VT.
N Governor speed sensing C
XDCR Power transducer C Unit power input to electric governor.
TYPE C = Control P = Protection Trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication, analog, digital, status lamps)
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Signal Description Type Notes
51ET Exciter transformer o/c
protection
P
49 GF Field overload 1 Set to coordinate with field winding thermal
characteristic
I f Field voltage indication 1 Transuded from DCCT ( satiable reactor )
Vf Field voltage indication 1
64 F Field ground detection P or
A
27 FF Failure of preferred field
flashing source
A Provision of this alarm assumes 2 sources
provided AC and DC. AC should be
preferred source to minimize chance of back
feeding field voltage onto battery if blocking
diode fails. Automatic transfer to alternate
source on failure of preferred source
41/a,41/
b
Field breaker position C,I
31/1,31/
b
Field flashing contactor position I
48E Exciter start sequence
incomplete
P,A Set to operate after normal time required for
field flash source to build terminal voltage to
level sufficient for exciter gating to
commence.
63F-1 Cooling fan failure A/P Failure of redundant fan (s).
27PS DC power supply failure P or
A
Trip or alarm depending on level of power
supply redundancy.
26ET-I Exciter transformer over
temperature –Stage I
A Indicating unit with dial contacts typical.
26ET-2 Exciter transformer temperature
–Stage 2
P
Table 4.1 – Control and Status Data Transmitted from excitat ion system to unit control switchboard
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58-1 Rectier transformer temperature A Thyristor fuse, conduction, or gating failure.
-
58-2 Rectifer failure –Stage 2 P
49 HE Heat exchanger failure A Various heat exchanger arrangements are
possible Once-through, closed system, etc
26RTD Exciter transformer temperature
indication
I Temperature detectors . Quantity variable
depending on number of secondary winding
and whether transformer is 3 phase or 3 x 1
phase.
70V Manual voltage adjuster with I Signal generated by potentiometer coupled to
70V motor drive.
70V/LSI,
2
70V End-of travel indication I Signal generated by limit switches coupled to
70V motor drive
90V Auto voltage adujster with
position
I Same as 70V.
90V/LSI,
2
90 V End-of –travel indication I Same as 70V/LSI,2.
70V/LS3 70V preset position C Interlock in start sequence
90V/LS3 90V preset position C Interlock in start sequence.
89LS Station service A.C test supply
switch position
I Optional
MAN Indication mismatch between
auto & manual
I To ensure bumpless transfer from AUTO to
Manual
AUTO Voltage regulator output and
manual
I MAN and MAN to AUTO
Balance Voltage setpoint
Balance Voltage setpoint
TYPE
C = Control P = Protect ion Tr ip A = Annunciation /Event recording T= temperature Monitoring
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I = indication (analog, digital, status lamps)
Table 4.2 – Control and Status Data transmitted from unit control Switchboard to excitation
SIGNAL DESCRIPTION TYPE NOTES
41 protective trips
Field tripping from generator P
41 control Field breaker tripping from manual control and unit shutdown sequence logic
C
41 close Field breaker closing from manual control and unit start sequence logic
C
IE Exciter de-excite C Close contact to initiate field flashing at 95% speed during auto start or under manual control
IE Exciter de-excite C Open contact to initiate phase back below 95% speed, unit separated form system
83VT Voltage transformer potential C Transfer exciter from auto voltage control to manual control
43AM Close contact transfer exciter to manual voltage regulator control
C
43VA Close contact to transfer exciter to auto voltage regulator control
C
70V Rum.
Back logic
Run 70V to preset position preparation for unit starting
C
90V Rum.
Back logic
Run 90V to preset position preparation for unit starting
C
70 V raise Raise manual voltage adjuster
C
70 V lower Lower manual voltage adjuster
C
90 V raise Raise auto voltage adjuster C
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90 V lower Lower auto voltage adjuster C
52G/a Generator CB Auxiliary switch
C De- excite control, disable power system stabilizer of-line.
Wicket gate position
Analog signal representing wicket
C Used to develop accelerating power input to PSS if required
TYPE
C = Control P = Protect ion Trip A = Annunciation /Event recording T = temperature Monitoring I = indication (analog, digital, status lamps)
Table 4.3– Operating Power, Air and Water from Service Equipment to
Excitation system
DESCRIPTION TYPE NOTES
Battery-fed field flashing DC
Station service field flashing
source
AC AC preferred source. Auto transfer to dc if ac
not available
TYPE C = Control
P = Protect ion Trip A = Annunciation /Event recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
Table 5.1 – Control and Status Data Transmitted from Step up Transformer to Unit Control Switchboard
Signal Description Type
Notes
CT Current signal for relaying and
metering
A, P, I
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71G Gas accumulation detection A Event recording (optional).
63G Gas pressure device A, P Event recording
63Q Main tank sudden pressure relief
device
A, P Hand reset contact (local). Event recording
63T Main tank over pressure switch A, P Trip generator breaker
49-1W 49-2W
Transformer winding temperature thermal device in each separate winding
A, T, P Temperature detectors embedded in each separate winding for first stage temperature control. RTD are in each winding because of the possibility of unbalanced loading.
26Q Top oil temperature indicator A, T Dial type oil temperature indicator at the transformer. First stage annunciation, tripping optional. Second stage tripping
71QC Conservator tank oil level indicator A Dial type indicator with maximum and minimum indicating levels. Tripping optional.
Table 5.2 – Operating Power, Air and Water from Service
Equipment to transformer Description Type
Notes
Power supply for DC control circuits
DC For uninterruptible systems.
Power supply for fans, pumps, ac control circuits
AC For FA, FOA transformers. If an FOW transformer is used, additional information and control signals may be needed, such as monitoring of the pressure difference between the oil and water systems.
Water supply for fire extinguishing system
W
Type AC =AC Power
DC =DC Power A =Air
Table 6.1 – Signals Transmitted from Plant Equipment to Generator Breaker
Signal Description Type
Notes
4 Unit control C Normal shutdown
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1XJ Breaker control switch, trip/close C
12G Generator overspeed P
25 Synchronizing equipment C
33 Wicket gate position switch C Permissive switch
38GB Generator bearing temperature P
38TB Turbine bearing temperature P
43XJ Breaker test switch C
49T Step-up transformer over temperature P
63T Step-up transformer sudden pressure P
71K Kaplan low oil P
80TBQ Turbine bearing oil P
38G Generator winding temperature P
43S Unit synchronizing selector switch C Permissive switch
Table 6.2 – Signals Transmitted from generator Breaker to Unit
Control Switchboard
Signal Description Type Notes
52a, b Breaker open-close C, I
27CB Generator breaker loss of dc control
power
A
61 Generator breaker pole failure P, A Trip is isolate breaker.
63a Breaker air pressure switch C Permissive switch.
63A Generator breaker low air pressure P, A
Type C =Control
P =Protection Trip A =Annunciation/Event Recording T =Temperature Monitoring I =Indication (analog, digital, status lamps)
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Table 6.3 – Inlet Valve and Draft Gate Controls for automatic operation of the Inlet Valve shall as follows: 1 Unit Control Board • Indicating lights for fully open/fully
• Position indication showing actual position of the gate
2 Local • Open/Close control switch 3 Annunciation • Failure of valve to open or close in response
to an automatic signal • Hydraulic system trouble
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4.4 MANUAL CONTROL, METERING AND PROTECTION SYSTEM 4.4.1 Scope of Supply and Design Criteria
Design, manufacture, testing, commissioning of manual control, metering and protection system which includes Electrical protection by conventional relay; manual control and metering of the Power House.
4.4.2 Standards
All materials and equipments shall comply in every respect with the requirements of the latest edition of the relevant Indian, British equivalent N.E. M.A. I.E.C. Standards or any other recognized International standards, except in so far as modified by this specification. Where standards offered are other than the Indian or British standards, copies of the relevant standard specification in English language must be attached.
4.4.3 Design Criteria
The control will have provision for start, stop,, manual synchronizing and emergency stop. Sequencing will be as per control of unit operation as given below: -
4.4.4 Protection and Metering Scheme
Requirements of metering and protection/scheme and the function performed by various relays are explained in following drawings(to be enclosed by Purchaser). i. Main Single Line Diagram ii. Interconnection with Grid iii. Protection & Metering Single Line Diagram iv. Auxiliary Power Single Diagram v. Unit Metering and Relaying Single Line Diagram Common tripping relays for similar functions have been provided with lockout facilities. All these relays shall have potential free contacts for trip and alarm purposes and externally hand reset type of flag indicators. They should preferable be housed in drawout type of cases with tropical finish. All the protective equipment will be housed in the Power Plant main control room. The details of C.T.’s for all the unit protection and metering are given in Drawings No-----. The secondary current of C.T.’s located in switchyard is proposed as 1 amp. because of long leads so as to ensure efficient and accurate operation of their protective scheme. 3.3 kV C.T.s and P.T. may be mounted on 3.3 kV switchgear panels’ alongwith relays.
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4.4.5 Protective Relays
A brief description of protective relay proposed is given below: 4.4.5.1 Generator Protection
i) Generator Differential Protection (87G)
The generator primary protection is proposed by high impedance type of circulating current relays having proper setting range. The relays will be of high speed type and shall be immune to A.C. transients. Necessary provision shall be made in the relay to ensure that the relays do not operate for faults external to the protected zone. The relays shall not maloperate due to harmonics in spill current produced by through faults or due to saturation on one set of current transformers during an external fault. Provision shall also be made for alarm /indication in case of current transformt fault.
The relay operation actuates lockout relay for complete shutdown of the unit Drawing No. -----.
ii) Generator ground fault protection (64G)
The generator neutral will be earthed through the primary winding of a distribution transformer of proper capacity and ratio. The secondary will be loaded by a suitable resistor rated for 60 seconds. A suitable voltage relay with continuous coil rating with proper setting is proposed to be provided. The relay shall be insensitive to voltage at third harmonic frequencies.
The relay operation actuates lockout relay for complete shutdown of the unit.
iii) Neutral Grounding Transformer and Loading Resistor
Neutral Grounding Transformer
a. Type Dry type, Natural air cooled, single phase.
b. Connection Between generator neutral and ground
Loading Resistor a. Construction Non-ageing, corrosion
resistant, punched stainless steel grid elements provided with necessary installations, and temperature rise not exceeding 300 deg. C.
b. Housing Enclosure with IP:22 degree of protection. However,
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transformer and resistor can be housed in same container with metallic partition.
iv) Generator over-voltage protection (59)
A set of single phase relays is proposed with suitable time delay setting so that operation of relay under transient conditions is avoided. The relay setting range is proposed from 110% to 150%. The relays shall be immune to frequency variation. Provision of instantaneous tripping element at some suitable setting is also proposed.
The relay is set to operate lockout relay for partial shutdown to speed no load position.
v) Negative phase sequence current protection (46)
Protection will detect unbalance in the outgoing lines which will be detected and operate the relay. The current transformer for this protection is proposed to be located on the generator neutral side.
The relay is set to operate the lockout relay for partial shutdown to speed no load position.
vi) Voltage restraint over current protection (51V)
This backup protection for the generator operates for over current which are accompanied by dip in voltage so that false tripping due to through faults are avoided. The relay is set to trip lockout relay for partial shutdown to speed no load position.
vii) Reverse power relay (32)
This relay is proposed because of grid connection. The relay is proposed to be set to trip lockout relay to speed no load position.
viii) Check Synchronising relay (25)
Check synchronising relay is provided to ensure the closing of the circuit breakers on synchronising at a phase angle not greater than about 7 degrees so as to prevent damage to circuit breaker especially in case of auto synchronising.
ix) Potential transformer fuse failure protection (60)
Suitable voltage balance relays are proposed to monitor the fuse failure of 3 sets of potential transformers and to block the relays (50/51 V or 40) or other devices that may operate incorrectly on the voltage due to fuse failure of potential transformers. The relay is set to give an alarm only.
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x) Mechanical Protections
Following mechanical protections are proposed for the generator:
e. Resistance temperature detectors in stator core (12 no.) and in the
bearings for indication, alarm and recording. RTD’s are to be provided by Generator Suppliers.
f. Turbine and generator bearing, metal and oil temperatures – alarm/shutdown.
g. Governor oil pressure low to block starting and low-low for emergency tripping.
h. Over speed for normal and emergency shutdown depending upon its extent.
i. Contractor will co-ordinate with Generator and Turbine supplier for mechanical protection.
4.4.5.2 Exciter Protection
i) Generator field failure protection (40) The tripping of the relay is set to open the excitation breaker main generator C.B., 33 kV trans. C.B. & UAT breaker and shut down the turbine on immediate shut down mode.
ii) Generator rotor earth-fault protection (64F) The protection shall consist of two stages. The first stage with a lower range shall be arranged to give alarm and annunciation. The second stage with a higher range shall carry out tripping of the gen. C.B., UAT breaker, field breaker and shut down the turbine on immediate shut down mode.
iii) Over current relay (51 EX)
This over current instantaneous relay in the excitation circuit before the excitation transformer will cater to rectifier transformer faults and other excitation system faults. This relay is set to trip excitation circuit breaker and bring the unit to rated speed at no load.
iv) Over excitation relay (OER) in the DC circuit and excitation relay (31) in the field flashing circuit are other relays proposed in the excitation system.
4.4.5.3 Station Service System
i) Over Current Protection (51)
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Suitable relays are proposed to be provided for unit auxiliary transformers over load protections. The relay will operate from the three current transformers on the Low Voltage side of the transformer and will be arranged to trip the Low Voltage breaker.
An instantaneous time over current relay is proposed from the CT’s on the 3.3 kV side of the auxiliary transformer. This relay at a higher setting will cater to transformer faults and the tripping of the relay is set to bring the unit to rated speed at no load.
ii) Phase sequence relay (47)
This relay on the station service system trips the LV circuit breaker so as to prevent operation of the three phase motors in the reverse direction
.
iii) Under voltage relay (27)
These relays have been provided to trip the LV circuit breaker
4.4.5.4 Step up 3.3/33 kV Transformer Protection
i) Generator Transformer Differential Protection (87 GT)
A sensitive percentage biased differential relay is proposed to be provided for each step up transformer protection with proper operating and bias setting. It shall have harmonic restraint feature to prevent its mal-operation due to magnetising in-rush surges encountered in normal power system operation. Provision shall also be made for alarm/indication in case of current transformer secondary circuits faults.
The C.T.’s on 3.3 kV side are proposed be located in the Generator neutral side and on 33 kV side in the switchyard. The auxiliary/interposing current transformers as required for the protection shall also be provided.
The relay is set to operate lockout relay for shutdown.
ii) Standby earth fault protection (64T)
For this protection Inverse Definite Minimum Time Lag type relay having suitable setting range and operating time is proposed. This relay is proposed to trip the unit circuit breaker and bring the unit to speed no load. The relay will be co-ordinated with line earth fault protection.
iii) Bucholz gas pressure relay for first stage alarm and second stage trip. iv) Transformer oil level and temperature for alarm & trip v) Winding temperature for alarm & trip
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4.4.5.4 Bus Bar Protection
Bus Zone Differential Protection (87 B1, and 87 B2) A high speed, high impedance type bus-bar differential protections proposed to be provided for each 33 kV bus zone. The scheme shall have separate and independent check and supervision features incorporated in it. Necessary separate C.T. cores shall be provided at the incoming and outgoing circuits for check features. The main zonal relay and check relay scheme will have their contacts connected in series in the trip circuit.
The protection will be capable of detecting all type of faults on the bus-bar. The sensitivity of protection shall be such that it does not operate for faults on the C.T. secondary wiring of the most heavily loaded circuit. C.T.’s on one side of the bus coupler/section breaker are proposed and inter-locked overcurrent relay will be provided.
The supervision relay will be capable of detecting open: Cross or broken C.T. secondary and pilots by employing sensitive alarm relay, which shall be connected across the bus wires of each protected zone. It shall be capable of taking the protection of the effected zone out of service by shorting the appropriate bus-wires.
`No volt’ relays to indicate failure of D.C. alarm and trip supply to the bus-bar protection scheme is also proposed to be provided.
High speed tripping relays shall be provided to trip the connected circuit breakers connected to the faulty bus bar.
4.4.5.5 33 kV Line Protection
Protective relay design for the 33 kV line is important because of high fault power from 33 kV grid sub-stations. Main features of fast acting protection system is tentatively proposed as follows:
Directional overcurrent and ground fault (51 D)
4.4.5.6 Over under voltage relay/Over under frequency relay
This relay shall be provided on the line and the bus to indicate grid failure conditions.
The protection requirement with respect to characteristics operating principle, tripping schedule and type of relays shall be discussed during detailed engineering stage, and Bidder shall provide the same to the satisfaction and approval of the Owner.
4.4.6 Metering
Meters as shown in Schematic drawing(to be enclosed by Purchaser shall be provided on unit control boards. These are summarised below:
4.4.6.1 Generator (Unit Control Board)
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i. 3 ammeters (each phase) ii. Power factor and kW meter iii. kVAR iv. Voltmeter with voltmeter switch v. kWH meter vi. Frequency Meter
4.4.6.2 Auxiliary Transformer
i. kWh meter ii. Ammeters (3 No.)
4.4.6.2 33 kV Feeder Panel
i. Voltmeter with voltmeter switch ii. Ammeters (each phase). iii. Recording kVAR iv. k.W. v. Power Factor meter
vi. kWh import / export meter.
4.4.7 Annunciation
Conventional 16 window annunciator for each generator turbine faults; 12 window each for feeder faults and Bus Coupler is proposed for important faults. Schedule for these windows may be proposed for approval by purchaser. All other annunciation will be on SCADA system.
4.4.8 Recorder All recording will be done on SCADA disk. 4.4.9 CTs/PTs and General Surge Protection Equipment 4.4.9.1 All current and voltage transformers required for protection system of the unit are
detailed in generator specifications shall have adequate VA burdens, knee point voltage, instrument safety factor and characteristics suitable for the application, and shall be subject to approval of the Owner. 33 kV CTs are detailed in separate section.9.1.1.
CTs/PTs used for different applications shall have following accuracy class: a) Differential protection CTs Class PS b) Protection CTs other than differential protection Class 5P10 c) Generator AVR/metering CTS for generator circuit Class 0.5 d) Metering CTs for 33 kV; 3.3 kV and 415 V switchgear Class 0.5 e) CTs for performance testing and low forward power Relay Class 0.2 f) Core balance CTs Class PS g) Protection PTs Class 3P h) PTs for generator metering, AVR synchronisation Class 0.5
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i) PTs for performance testing and low forward power relays Class 0.2 CTs and PTs details proposed will be submitted for approval by purchaser.
4.4.9.2 Generator Line Terminal and Neutral Grounding Cubicles
These shall be provided as per detailed given in generator specifications. 4.4.9.3 33 kV Current Transformers and Potential Transformers
The technical requirement and location of the CTs are given in the unit metering and relaying drawing (enclosed). The generator suppliers shall supply suitable current transformers for the protection scheme and these shall be in the neutral grounding cubicles.
The potential transformers should be suitable for metering and protection scheme enclosed.
4.4.10 Control and Relay Panels
Floor mounted, sheet steel simplex type control and relay panels with the following equipment mounted on them shall be as follows. The details of the panel and equipment will be supplied for approval by purchaser. 1) Generator transformer control and relay panel - -- Sets. 2) 33 kV feeder control and relay panel - -- Sets. 3) Synchronising panel - 1 no.
4.4.11 Test Blocks
Test blocks shall be provided on switchboards where test facilities are required but are not provided by use of drawout type meters or relays. The test blocks shall be of the back connected semi-flush mounted switchboard type with removable covers. All test blocks shall be provided with suitable circuit identification. The cases shall be dust tight. Test blocks shall be rated not less than 250V at 10 amps and shall be capable of withstanding a di-electric test of 1500 V, 50c/s for one minute. All test blocks shall be arranged to isolate completely the instruments or relays from the instrument transformers and other external circuits so that no other device will be affected and provide means for testing either from an external source of energy or from the instrument transformers by means of multiple test plugs. The test blocks and plugs shall be arranged so that the C.T. secondary circuits cannot be open circuited in any position, while the test plugs are being inserted removed.
4.4.12 Factory Tests for Unit Control Switchboards
1. Review front and rear elevations versus the final approved drawings. Check each item of equipment for proper location and verify the instrument/catalog number is correct per the specification.
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2. Review the interior of the UCS in the same manner as the elevations. In addition, verify the lighting is adequate and grounding connections are provided.
3. Check anchor channels and cable entrances. Confirm they are in accordance with the drawings.
4. Review test certificate or witness the insulation resistance test of all wiring, current transformers, and potential transformers.
5. Check approximately 5 to 10 percent of the internal cabling. Verify that the following items conform to the drawings : • Cable numbers; • Terminal block designations; • Terminal designations on individual components such as control switches
and lockout relay; • Raceway layouts; and • Equipment identification nameplates.
6. Activate all protective relays. Confirm that the appropriate lockout relay is
energized and the correct annunciation and/or printout occur. 7. Confirm that settings of all protective relays are in accordance with approved
documents. 8. Check all annunciation points. 9. Check factory calibration of all devices possible, including electronic speed
relays, current and potential transformers, and vibration monitors. 10. PLC checks:
• Check the I/O racks for type and number of analog and digital I/O cards; • Check for future expansion capabilities on the I/O racks; • Check for surge protection provided on the I/O rack and I/O cards; • Identify grounding connections for the PLC and the I/O rack; determine
whether chassis and logic grounds are the same or separate (this will affect the type and quantity of external surge protection required);
• Review the PLC ladder diagram viewed on the video display terminal versus the final approved PLC software coding documentation; and
• Verify that modem connections are provided and functional.
11. Perform the function checks listed below with the final approved schematics, PLC software coding, and control block logic diagrams in front of you. All premissives and interlocks should be provided by using the “dummy” toggle switchboard to provide these inputs. • Manual start/stop sequence (does not apply to redundant PLC control
schemes); • Auto start/stop sequence; • Manual emergency stop sequence; • Automatic emergency stop sequence (usually performed by activating one
of the lockout relays while in the “normal running” mode ); • Change position of all control switches as follows (typically done while in
the normal running mode);
- Local control to remote control - Remote control to local control
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- Manual control to automatic control - Headwater level control “OFF” to “ON” - Headwater level control “ON” to “OFF” - Excitation manual control to excitation automatic control - Excitation automatic control to excitation manual control; and
• Verify the performance of the automatic synchronizing circuit and the manual sync-check relay (if provided).
4.4.13 Field Tests for Unit Control Switchboards
1. Verify tags on all factory-calibrated instrumentation devices. 2. Check all external interconnection wiring against the approved power
house/equipment drawings, verifying the following items : • Cable numbers and type; • Terminal block designations; and • Raceway layouts
3. Perform point-to-point continuity and megger tests on all external cabling. 4. Calibrate all remaining instrumentation devices. 5. “Bench test” all protective relays to ensure proper settings. 6. Perform functional checks tests on all unit and station auxiliary equipment
controlled from the UCS to verify proper operation. 7. Perform functional checks on unit start/stop sequences, duplicating the factory
sequences. These check should be performed first with the associated power circuits de-energized, and then with both power and control circuits energized.
8. Methodically document steps 1 through 7 to ensure that no cables, instrumentation devices, protective relays, or control systems have been overlooked.
9. Water-up the unit and perform all start/stop sequences. 4.5 SUPERVISORY CONTROL AND DATA ACQUISITION (SCADA) SYSTEM 4.5.1 Scope of Supply and Design Criteria
Design, manufacture, testing, commissioning of the Supervisory Control and Data Acquisition (SCADA) system which includes all equipments required for measurement, control, metering protection data logging data recording, annunciation and sequence of event recorder, main computer, display unit with keyboard.
The SCADA system required should provide monitoring of parameters listed in
section 7.0 and control in grid mode and isolated mode operation of the Hydel Power
station centralized control room.
♦ Reliable safe control of the unit with very high availability
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♦ Automatic startup, on-load control and shutdown of the units by the control system
♦ Control of auxiliary equipment ♦ Remote monitoring of all plant status and alarm information ♦ Remote normal startup, on-load control and shutdown of units by operators.
SCADA system should have following controllers
♦ Unit Controller. ♦ Common Plant Controller/Supervisory Controller at Power House control
room
The SCADA system where it is proposed to be set up in this specifications shall be designed for safe, reliable, efficient and easy operation of Hydro Turbine Generator and its associated auxiliaries and transmission lines.
The SCADA system shall consist of a microprocessor based computer system, a dedicated sequence of events recording system, a health/condition monitoring and analysis system, system cabinets, local panels, sensors, local instruments, erection hardwares, interposing relays etc.
The SCADA to be supplied shall be of proven design; operation in at least four power house for more than 3 years and will be subject to approval by purchaser and will consist of following.
(a) Main microprocessor based computer system. (b) Data logger/sequence of events recorder. (c) 19” Colour graphic monitors with key boards (d) System console (e) Hard copy plotter/printer (f) Complete field instruments like transmitter/transducers, sensors, interposing
relays, erection hardwares all interconnecting cables etc. (g) Bidder shall supply all necessary software required for the SCADA system
including operating system, compiler, application software etc. (h) The transducers required for the measurement of electrical parameters. The
output of transducers will be 4-20 mA.
The SCADA system shall be capable of performing the following functions in real time.
a) Acquire data from primary sensors. b) Process and retain data for each primary sensor. c) Perform detailed thermal and vibration analysis. d) Report machine performance in tabular and graphical format. e) Sequence of event logging. f) Supervisory control of auxiliaries, governing system, excitation system, circuit
breakers, including synchronising. g) Display software including system monitoring alarm processing and display of
data, fault, and status of devices.
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h) Application software including state estimation, bad data detection, and on line power flow.
i) Data logging and report generation. j) Report alarms. k) Predict need for shut down and maintenance of equipment. l) Software shall be such that the monitoring system will take care of the
transient parameters during system run-up and shut down. m) Software shall be modular and upgradable. n) The SCADA software shall run in co-ordination with SCADA software for
gate control operation. It can receive data of Gate positions etc. from it and send generation etc. data to it.
4.5.2 Response Time
Fast response time of computer system is required. Bidder will intimate following: (a) Time duration required to update a graphical display from the instant a field
contact changes state. (b) Time duration from the instant a control is activated at the operator station
until the command is implemented at the field device. (c) Overall time duration to process and lag an alarm once it is received at the
computer.
Methodology by which these “times” were verified must be given. Acceptable time shall be verified at the factory acceptance test.
4.5.3 Equipment Architecture and Protocol
Open architecture system shall be followed. Interface or operating standards for the following shall be intimated and should comply with ISO/IEC 12119.
• Communications • Operating system • User Interface • Data base
Each of these elements should be capable of being replaced by or communicate with system elements provided by other vendors.
4.5.4 Plant Operation Philosophy
The normal, start-up, shut down and emergency operations of the hydro turbine generator, auxiliaries and feeders shall be performed in three different ways as follows:
(i) PLC based governor control panel for unit and plant control (ii) Control from Power House control room (iii) Manual control panel
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The Control Engineer shall be able to perform the following operations from the CRT through keyboards.
a) Call up mimic, alarm, data display. b) Call up control display to carry out control operations for hydro turbine
generators and its associated auxiliaries and main & electrical power supply systems controlled from CRT/key board.
c) Demand, logs, report including performance calculation reports, sumaries, trends and plots for hydro-turbine generator and its auxiliaries and main & auxiliary electrical power supply system.
d) The control engineer shall be able to set up all pre-start check of devices from the CRT/keyboard for unit starting such as :
1) The wicket gate control 2) The control of generator brakes 3) Power supply to the governor 4) Load/frequency device selection on speed setting mode. 5) The selection of speed droop equal zero. 6) The blades at fully open position etc.
e) The control engineer shall be able to set the interlocks to start the unit from the
CRT/key board and once the start command is given following sequence shall take place through the SCADA system.
1) The governor pump shall start. 2) When the oil pressure is established in the governor circuit, blades shall set at
the starting position. 3) Release generator brakes. 4) After having ensured that the bakes are released and blades are in starting
position command shall be given to open the wicket gates. 5) With opening of wicket gate unit speed shall rise. 6) At 90% unit speed, generator shall be excited, wicket gate shall be stopped
and its position maintained by energizing governor relays speed adjustment, blades/movements shall be achieved.
7) When unit frequency and phase voltage is matched to that of existing power system, unit circuit breaker shall be closed.
8) After unit breaker is connected to the system, governor parameters shall be set to automatic mode.
f) The control engineer shall be able to shut down the unit during normal condition in
the following sequence. 1) Level control on governor shall put off 2) Blades shall close 3) When blades are closed, wicket gate shall be allowed to close. 4) When no output power is sensed unit breaker shall be tripped. 5) After unit breaker is open, blades shall open again. 6) When downstream gate is closed and unit speed is 30%, brakes, shall be
applied.
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g) The control engineer shall also be able to trip the unit during emergency condition with the following sequence.
1) Unit breaker shall be tripped. 2) Wicket gate shall be closed. 3) Other sequence of operation as per the normal shut down. 4.5.5 Parameter to be monitored from SCADA The SCADA system shall be complete with all primary sensors, cables, analyzers/
transmitters, monitors, system hardware/ software and peripherals etc. to monitor/ control the parameters for control, protection, annunciation, event recording etc different equipments including.
• Generator stator and rotor winding temperatures. • Lube oil temperature • Radio frequency interference • Generator air gap monitoring. • Acoustic levels • Level measurement • Turbine blade tip clearance • Governor control monitoring of turbine speed. • Generator terminal voltage, current, KW, KVAR, KVA, KWH,
Frequency, power factor, field voltage and field current. • Annunciation for violation of permissible limits of the above
parameters. • Turbine bearing temperature. • Guide bearing temperature. • Guide bearing oil level. • Guide vane bearing oil temperature. • Generator bearing temperature. • Generator winding temperature. • Turbine speed. • Generator speed. • Governor oil pumps, oil pressure indicator and low pressure switch. • Inlet pressure gauge at inlet of turbine. • Vacuum gauge for draft tube pressure. • Level indicator for level in the fore bay/Tailrace.
• Annunciation Bidder shall provide suggestions relating to measurement points and sensors. If in his
opinion, an enhancement in condition monitoring capability can be attained by use of additional sensors these should be provided and details to be indicated in the bid.
4.5.6 Hardware Requirement
The key hardware features of the controller should be as follows:
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♦ Standardized hardware technology ♦ Highly modular design ♦ Expandable ♦ Operation over a wide voltage range ♦ Intelligent I/O modules ♦ Central and distributed I/O ♦ Communication with other controllers and computers ♦ Remote fault diagnostics
It should include all transient suppression, filtering and optical isolation necessary to operate in a power plant environment. The type of controllers to be used in the SCADA system should be selected to meet specific plant requirements described below including availability, number of plant I/O, cycle time and type of communications link. The modular design of the controllers should be such that they are easily integrated into the control system requiring the minimum of engineering.
4.5.6.1 Unit Controller
Redundant microprocessor based/PLC based governor system control should be interfaced with SCADA powerful enough to perform all the required functions mentioned above. It should have capability to implement closed loop PID function for governing. The scan time of the complete sequence for each process should be less than 100 msec. It should have lock to prevent unauthorized modification and be capable of detecting hardware and software failures. It may also have digital relays for over current, over-voltage and differential generator protection. It should have following hardware features. It should have a console and keyboard to program the controller as well as communicate with Supervisory controller. Unit controller should support remote management and remote programming for supervisory controller.
4.5.6.2 Shut down Hardware
The controller should have a conventional relay logic shutdown circuit. This circuit should include start and stop relays for controlling the turbine. The start relay circuitry should provide for auto and manual control capability. A controller fail relay should drop out the start relay when the auto relay is on. All shutdown hardware should be powered by the station battery. The stop relay should drop the start relay whenever a contact input which is strapped for shutdown on a digital input module is closed.
4.5.6.3 Digital Status And Alarm Inputs
The controller should be capable of connecting to at least 60 contact type inputs representing digital status and alarms. All contact inputs should be sensed through optical couplers with an isolation voltage of at least 1500 Volts. The controller should accept station battery voltage level inputs. Controller input modules should be strappable for 24 Volt station batteries. Controller digital input modules should also have straps to allow any contact input to cause a hardware shutdown directly to the stop relay.
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4.5.6.4 DC Analog Inputs
The controller should accept 0-1ma, 0-5V, 4-20ma or 1-5V DC analog signals. The controller should be able to measure DC analog signals with as much as 5 volts common mode signal with differential inputs. The controller should provide ground straps that can be inserted on the negative lead of any input signal that should be grounded at the controller. The controller should also provide selective terminating resistors for 1ma and 20ma signals. The DC analog signals should be converted to digital signals using at minimum 12 bit analog to digital converter in the controller with all conversion errors considered the controller should maintain an accuracy of 0.1% or better of full scale and a resolution of 1 part or less in 2000. All DC analog inputs should be protected from transient spikes and voltages with circuitry that meets the IEEE surge withstand test.
4.5.6.5 AC current inputs
The controller should connect directly to current transformers. The controller should accurately measure all current inputs from 0-6.25 amps. It should withstand 10 amps continuously and 50 amps for 1 second. The controller should be able to measure magnitude of the current with a true RMS to DC converter and its phase shift with respect voltage. The current measuring accuracy should be to .1% and the phase shift accuracy should be to .1 degree. The controller should induce a burden of less than .5VA on each current transformer it connects to.
4.5.6.6 AC voltage inputs
The controller should connect directly to the potential transformers. The controller should accurately measure voltage inputs from 80 to 150V AC. It should withstand up to 200V AC continuously. The controller should be able to measure the magnitude of the voltage with a true RMS to DC converter and measure the phase shift of the voltage with respect to current. The voltage measuring accuracy should be to .1% and the phase shift accuracy should be to .1 degree. The controller should induce a burden of less than 1 VA in each potential transformer that it connects to.
4.5.6.7 Control outputs
The controller should provide control relays to operate the circuit breaker, voltage regulator, and other equipment. The contacts should be DPDT rated 125 VDC at 0.5 A. Two contacts should be available from the DPDT relay and either should be strappable as normally closed or normally open. An optional high-powered relay should be available that provides one normally open contact rate 150 VDC at 10A. Each relay should have an LED indicator mounted on a manual control panel to indicate the status of the relay, on or off. Next to the indicating LED should be a switch to operate the relay manually. Each switch/LED should be clearly marked as to its function.
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4.5.6.8 RTD inputs
The controller should have provisions to connect directly to RTDs. RTD readings should be corrected for nonlinearly and readings should be accurate to + 0.25oC. The temperature range should be 0-160oC. The controller must have a 10, 100 and 120 ohms 8 input RTD module. The correct linearizing curve should be selected by configuring. The controller should be capable of reading temperatures from eight RTDs. If eight RTDs are not required, any of the RTD inputs should be able to be used as a 4-20 mA analog input. Each of the eight inputs should be assigned three alarm set points; two high alarm set points and one low alarm set point.
4.5.6.9 Analog outputs
The controller should output 4-20ma signals for calculated signals such as kW, kVARS, power factor, frequency, voltage, and current. The signals should be isolated outputs with 1000 common mode voltage capability. The accuracy of these outputs should be better than .25%.
4.5.6.10 Alarm outputs (option)
The controller should be capable of outputting contacts for alarms that it generates internally. The contact rating for these alarms should be 1 Amp. at 24 VDC. All digital inputs should be capable of meeting the surge withstand capability in accordance with ANSI/IEEE C37.90.
4.5.6.11 Electrical transducers
The controller should connect directly to current transformers (CTs) and potential transformers (PTs). The controller should be capable of deriving the generator voltage (line to line and line to neutral), generator amps, generator WATTS, generator VARS, generator Power factor, generator kVA, generator frequency and bus frequency from the CTs and PTs: The controller should be configurable for open delta (line to line) or star (line to neutral) connected CTs and PTs.
4.5.7 Supervisory Controller
Standard Desktop Personal Computer having fast speed should be used as Supervisory Controller and should at minimum have following configuration:
4.5.8 Speed Sensor
A speed sensor to be mounted on generator unit shaft giving output as 4 to 20 mA / 0-5 V DC is to be provided.
4.5.9 Wicket gate position transducer
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It should comprise of LVDT mounted on hydraulic cylinder for actuating wicket gate.
It should convert linear movement of cylinder into 4-20 mA signal. 4 mA should
correspond to 0% and 20 mA to 100% stroke of the servomotor.
4.5.10 Head water/Tail water level transducer
Two level sensors, one for Headwater and one for Tail water should be provided.
4.5.11 Speed switches Speed switches should be provided for application of brake, overspeed tripping and creep at 30%, 112% and 5% of the rated speed respectively.
4.5.12 Printers
Printer/Hard copy units must be provided with supervisory and unit controllers.
4.5.13 Recorders
The plant control system should include video recording system of selected parameters i.e.
Generator temperature etc.
4.5.14 Factory Tests for Unit Control Switchboards
1. Review front and rear elevations versus the final approved drawings. Check each item of equipment for proper location and verify the instrument/catalog number is correct per the specification.
2. Review the interior of the UCS in the same manner as the elevations. In addition, verify the lighting is adequate and grounding connections are provided.
3. Check anchor channels and cable entrances. Confirm they are in accordance with the drawings.
4. Review test certificate or witness the insulation resistance test of all wiring, current transformers, and potential transformers.
5. Check approximately 5 to 10 percent of the internal cabling. Verify that the following items conform to the drawings :
• Cable numbers; • Terminal block designations; • Terminal designations on individual components such as control switches
and lockout relay; • Raceway layouts; and • Equipment identification nameplates.
6. Activate all protective relays. Confirm that the appropriate lockout relay is
energized and the correct annunciation and/or printout occur.
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7. Confirm that settings of all protective relays are in accordance with approved documents.
8. Check all annunciation points. 9. Check factory calibration of all devices possible, including electronic speed
relays, current and potential transformers, and vibration monitors. 10. PLC checks:
• Check the I/O racks for type and number of analog and digital I/O cards; • Check for future expansion capabilities on the I/O racks; • Check for surge protection provided on the I/O rack and I/O cards; • Identify grounding connections for the PLC and the I/O rack; determine
whether chassis and logic grounds are the same or separate (this will affect the type and quantity of external surge protection required);
• Review the PLC ladder diagram viewed on the video display terminal versus the final approved PLC software coding documentation; and
• Verify that modem connections are provided and functional.
11. Perform the function checks listed below with the final approved schematics, PLC software coding, and control block logic diagrams in front of you. All premissives and interlocks should be provided by using the “dummy” toggle switchboard to provide these inputs.
• Manual start/stop sequence (does not apply to redundant PLC control
schemes); • Auto start/stop sequence; • Manual emergency stop sequence; • Automatic emergency stop sequence (usually performed by activating one
of the lockout relays while in the “normal running” mode ); • Change position of all control switches as follows (typically done while in
the normal running mode);
- Local control to remote control - Remote control to local control - Manual control to automatic control - Headwater level control “OFF” to “ON” - Headwater level control “ON” to “OFF” - Excitation manual control to excitation automatic control - Excitation automatic control to excitation manual control; and • Verify the performance of the automatic synchronizing circuit and the
manual sync-check relay (if provided). 4.5.15 Field Tests for Unit Control Switchboards
1. Verify tags on all factory-calibrated instrumentation devices. 2. Check all external interconnection wiring against the approved power
house/equipment drawings, verifying the following items : • Cable numbers and type; • Terminal block designations; and • Raceway layouts
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3. Perform point-to-point continuity and megger tests on all external cabling. 4. Calibrate all remaining instrumentation devices. 5. “Bench test” all protective relays to ensure proper settings. 6. Perform functional checks tests on all unit and station auxiliary equipment
controlled from the UCS to verify proper operation. 7. Perform functional checks on unit start/stop sequences, duplicating the factory
sequences. These checks should be performed first with the associated power circuits de-energized, and then with both power and control circuits energized.
8. Methodically document steps 1 through 7 to ensure that no cables, instrumentation devices, protective relays, or control systems have been overlooked.
9. Water-up the unit and perform all start/stop sequences. 4.5.16 Additional Factory and Field Tests for Distributed Control Systems
1. Point-by-point database check. 2. Database linkage to graphical displays. 3. Response times during normal loading and high activity loading scenarios for:
• Graphical display updates; • Control sequence implementation; • Alarm processing and logging; and • Sequence of events recording
4. Communications connectivity/protocols. 5. Man-machine interface (MMI) user capabilities. 6. Application software functionality.
4.5.17 Data/ Document to be furnished by the Bidder
Bidder shall furnish the following data/documents with the Bid.
♦ All technical parameters such as baud rate, frequency, memory capacity input/output capacity of modules expansion capacity of the SCADA system, etc.
♦ Input/ Output list. ♦ List of parameters to be monitored from CRT/key board and the details of the
same. ♦ Redundancy provided for any of the equipment. ♦ List of application software. ♦ Bill of material ♦ Price schedule as per the enclosed schedule. ♦ Type of Cables. ♦ List of essential spares. ♦ Experience list. ♦ Manual/ catalogues of every equipment supplied by him. ♦ Plant operation philosophy.
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SECTION -V TECHNICAL SPECIFICATION FOR CONTROL PROTECTION, METERING AND SUPERVISORY CONTROL AND DATA ACQUISITION SYSTEM (SCADA) (FOR SHP OF ABOVE 5 MW TO 25 MW CAPACITY) 5.0 SCOPE
The Contractor shall design, fabricate, assemble, test at manufacturers’ works, supply, deliver, erect, test at site, Commission and train owner’s operating personnel for the Control, Protection and Monitoring Equipment and System for power generation, transformation and transmission and comprising of following. A Manual (conventional) Control and Protection System. (iii) Unit control, metering and protection relay panels (For each unit). (iv) --- kV Feeders control, metering and Protective relay panels. (v) --- kV Bus coupler control and relay panel. B Supervisory Control and Data Acquisition Equipment (i) Redundant Personal Computer/Mini computer based SCADA for supervisory
control (ii) Offsite supervisory control and data acquisition. The SCADA equipment will
be provided in the centralized control room of offsite station. (iii) A programming and training console at centralized control room
. C. Communication Link (i) Dedicated communication system between control room to off-site control
centre alongwith terminal equipment for control and local area network for distributed control and for voice communication.
(ii) Voice communication between control room, interlinking grid substation and offsite centralized control room.
5.1 APPLICABLE STANDARD
1. ANS/IEEE 1010 – 1987 – IEEE Guide for Control of Hydroelectric Power Plants 2. IS/IEC/ISO Standard Mentioned in Text
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5.2 CONTROL AND MONITORING SYSTEM General Considerations
Considerations involved in providing control and monitoring systems for the power plant and the switchyard are as follows:
h) Main Single Line Diagram is shown in drawing (to be enclosed by Purchaser); Metering and Relaying as proposed is shown in drawings(to be enclosed by Purchaser);
i) The power house is proposed to be controlled by supervisory control from control room of powerhouse as well as from offsite control centre. Accordingly provision is to be made for manual and automatic control for unit starting, unit stopping and running control at the power house with provision for supervisory control and data acquisition at power house as well as in centralized offsite control room.
j) Dependable digital controls for system control with conventional manual control as backup are proposed.
k) Power house units operation and loading is proposed to be Canal/HRC water level controlled
l) The turbines, generators, transformer and other equipment proposed for the unit will be provided with necessary sensors and actuators. Intake gates/MIV with capability of gravity closing under emergency shall also be provided on upstream side.
m) Emergency conditions (power house unit tripping etc.) will be taken care of by operating regulating Bypass Gates. For this purpose suitable provisions will be made in the control.
n) The generators are proposed to be provided with static excitation system. o) ---- number 11/--- kV unit transformers of --- MVA capacity each are
proposed to step up the generated power to --- kV. p) A single sectionalised --- kV bus is proposed for reliability. k) Entire power is to be fed into --- kV grid as shown in enclosed drawing.
The scheme will be designed in accordance with ANS/IEEE – 1010 and will be subject to approval by owner.
5.3CONTROL AND MONITORING OF PLANT EQUIPMENT 5.3.1General
The control system shall receive input signals from main equipment such as the turbine or the generator, and from various other equipment, such as the governor, exciter, etc. Status inputs shall be obtained from control switches, level and function switches indicative of pressure, position etc, throughout the plant. The proper combination of these inputs to the control system logic will provide outputs to the governor, the exciter, and other equipment to start or shutdown the unit. Any abnormalities in the inputs must prevent the unit’s startup, or if already on-line,
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provide an alarm or initiate its shutdown, depending upon the magnitude of abnormality. The unit control boards should be designed to perform the following functions: (ii) Information receipt and monitoring (viii) Start/stop sequencing control (ix) Annunciation of alarm conditions (x) Temperature information monitoring (xi) Metering and instrumentation signals display (xii) Event recording, when required (xiii) Synchronizing and connecting the unit to the system The unit control board is the central control means and communicates with the main and associated equipment through hard wire or multiplexing.
5.3.1.1 Level Controlled Operation of Power Units :
The power units operation is proposed to be level controlled so that in case of variation in canal/HRC water level due to discharge variation, loading on the power units is automatically adjusted to available water and energy output is optimised, unnecessary gate operation avoided and canal water level maintained between permissible limits. Redundant level monitoring system – one float operated and the other non float operated shall be provided.
5.3.1.2 --- kV line Control
Manual control of the --- kV SF6 breaker is proposed in the power house and supervisory control in the centralized control room as well as at offsite control centre.
5.3.1.3 Station Service System
The unit auxiliaries are proposed to be provided automatic control to suit the unit control as proposed for manual/supervisory control centralized control room and off- site control.
5.3.1.4 Annunciation
Annunciation system is proposed to be designed for control of the unit from the powerhouse as well as supervisory control in centralized control and offsite control. The normal annunciators consisting of indicating lamp and relay assembly is proposed to be provided on the unit control boards in the power house. The remote annunciation for supervisory control will be part of digital control system.
Data logging – Data will be stored in hard disc and printed every half an hour for which printer will be provide at centralized control room as well as off-site.
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5.3.1.5 Auxiliaries Control
Centralized controls of the power distribution and control boards is proposed for unattended automatic operation and for remote control from power house no. 4. Automatic switching of selected standby and emergency auxiliaries on failure of running auxiliaries is proposed. Automatic change over of entire unit auxiliaries to alternate source of supply is also proposed.
5.3.1.6 Switchgear and Motors
Air break switchgear is proposed to reduce fire hazard. The opening/closing time of switchgear may not exceed 8 cycles so that stalling of motors on change over does not take place. All motors are direct on line starting and are therefore high starting torque.
5.3.2 Control and Status Data
Control and status data to be transmitted from various equipment to Unit Control Board and from Unit Control Board to the equipment etc is detailed below. This is tentative and may be increased or decreased as required with owner’s approval.
Information and control signals will be needed between the control board and each of the following:
Canal/HRC water level
Turbine Table – 5.1.1 to 5.1.3 Turbine speed governor Table – 5.2.1 to 5.2.3 Generator Table – 5.3.1 to 5.3.7 Generator excitation system Table – 5.4.1 to 5.4.3 Unit transformer Table – 5.5.1 to 5.5.3 Circuit breaker and switches Table – 5.6.1 to 5.6.2 Intake gate/MIV and draft gate Table - 5.7
Additionally, control signal shall also be from Auxiliary equipment, Fire Protection, Auxiliary AC Power Supply, DC Power supply, Service Water, Service Air shall be provided as per IEEE – 1010.
These equipment blocks represent auxiliary service equipment needed for the proper operation of the generating plant. Abnormal conditions of this equipment will be alarmed.
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Table- 5 .1 .1 - Control and Status Data Transmitted form Turbine to Unit Control Switchboard
SIGNAL DESCRIPTION TYPE NOTES
38TG Turbine guide bearing temperature
T,A,P,I Temperature detectors, Provision for mounting two sensors in bearing shell.
38QTG Turbine guide bearing oil temperature
T,A,P,I Temperature detector in bearing oil reservoir.
71QTGH Turbine guide bearing oil level high
A Sensor in bearing oil reservoir, with direct reading visual indicator .
71QTGL Turbine guide bearing oil level low
A Sensor in bearing oil reservoir, with direct reading visual indicator
39 TV
Bearing / shaft vibration detector
A,P
Vibration probes installed on guide bearing housing at 90º. to each other, for detection of excessive bearing and shaft vibrations. Used in conjunction with probes on generator guide bearing.
33SP
Wicked gate shear pin failure
A Shear pin failure while closing wicket gates due to obstruction
80WB Bearing cooling water low flow
A Pump failure, obstructed piping or pipe rupture.
71WTH
Turbine pit water high level A, C
Senses excessive water level in turbine pit due to plugged drains or major seal failure. One contact operates submersible pump.
63AMS
Turbine shaft air maintenance seal applied
A, P
Contact blocks unit startup and initiates shutdown if seal applied during running
SCWP
Water pressure in Intake P, I
Direct reading on transducer operated gauge. Unit startup interlock, shutdown if loss of pressure in running unit
DTWP Draft tube water pressure-vaccum
I
Direct reading on transducer operated gauge
48TG
Turbine greasing system failure ( if greasing system provided )
A Alarm if lubrication cycle not completed
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74TG Turbine greasing system low voltage( if greasing system provided )
A
Detects failure of power supply to solenoid valve used to control greasing cycle.
Wicket Gate Servomotor Position
C
Feedback to the governor control system.
Runner Blade Servomotor Position
C
Feedback to the governor control system.
TYPE C = Control
P = Protection Trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
NOTE – Wicket gate automatic lock funct ions are descr ibed in sect ion 3H
Table- 5 .1 .2 - Control and Status Data Transmitted from Unit Control Switchboard to Turbine
SIGNAL DESCRIPTION TYPE NOTES
1GS Turbine grease system
Start/Stop (if greasing system provided)
C Enables grease system when uni t is running.
1TL Turbine lube oi l system star t /s top
C Enable turbine lubr icat ion pr ior to uni t
run. Type
C = Control
P = Protection Trip A = Annunciat ion/Event Recording
T = Temperature Monitoring I = Indication (analog, digital, status lamps)
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Table-5.1.3 - Operating Power, Air and Water from Service Equipment to Turbine DESCRIPTION
TYPE NOTES
Power supply for control and protection devices
DC
Power supply for turbine pit water pump AC
Air supply for shaft maintenance seal. A
Water supply for bearing oil coolers and turbines seals
W
Power supply for Lubricating oil system for bearing
AC May be alternately fed from DC.
Type AC = AC Power DC = DC Power A = Air W = Water Table 5.2.1 – Control and Status Data Transmitted from Governor to Unit Control
Switchboard
Signal Description Type Notes
N Speed indication I Methods of developing the speed signal include the following :
- Hall-effect, eddy current, magnetic sensors operated in conjunction with toothed wheels or other devices directly connected to the generator shaft (speed signal generator – SSG)
- Voltage transformers connected to the generator output leads must be capable of operating at very low residual voltages in absence of field excitation
12-X
Over-speed C, P Over-Speed Switch should be actuated mechanically by means of a centrifugal device mounted on the turbine shaft.
12-X1 Over-speed, C, P Electrically actuated speed relays by comparing
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13-X 14-X
Synchronous speed and under speed switches
the speed signal to a reference signal
65SF Speed signal failure
A,C,P Loss of speed signal may initiate control action i.e. shutdown of the unit and annunciation.
39C Creep detector operation
A,C Control action upon detection of shaft movement after shutdown may include any or all of the following :
- Start thrust/guide bearing HP oil pump - Release brakes - Drop intake gates - Alarm - Start turbine guide bearing oil pump
65Ss Start/stop solenoid
auxiliary contacts or gate limiter limit switches
C,I Provides information of starting /stopping process.
65SNL Speed-no-load solenoid aux. contacts or gate position
C,I Provides confirmation of 65SNL operation. Used to seal in remote controls and provide remote indication.
WG Wicket gate position indication
C, I Typically derived from potentiometer or LVDT coupled to restoring connection from wicket gate servomotor.
33WG Wicket gate position switches
C,P,I Typical uses of gate position switches for control and indication:
- Generator brake application (that is, apply brakes at low speed if gates at 0%)
- Turbine gate lock (apply at 0% gate position)
- Trip generator breaker as gates pass through speed-no-load position (auto-stop, protective shutdowns without overspeed)
- Incomplete stop detection - Unit running detection - Initiate time delay for stopping auxiliaries - Reenergize starting relays to provide
restart after momentary loss of power
71 QP Governor Oil Pressure Unit – oil level switches in Pressure Vessel
A, P Alarms for high, low and extreme low levels. Shutdown for extreme low level, air admission for high level.
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63Q Governor Oil Pressure Unit -pressure switches on Pressure Vessel
A, P Pump control, alarms for low, and extreme low pressures, shutdown for extreme low pressure.
71 QS Governor Oil Pressure Unit –level switches for oil level in sump tank
A Alarms for high and low oil levels.
26QS Governor Oil Pressure Unit – sump tank oil temperature high
A Indicative of excessive governor action.
6Q Governor Oil Pressure Unit – standby pump operation
A Indicative of excessive governor action or pump failure
27PS Governor power supply failure
A,C,P Indicates failure of input AC or DC power or failure of regulated DC power supplies. May result in unit shutdown depending upon level of power supply redundancy.
63AB Generator air brakes applied
C,I Indication and auto-start interlock.
63ABS
Generator air brake supply pressure low
A
33WGL
Wicket gate automatic lock applied/released
C, I Indicates status of the gate lock (applied on shutdown when gates at 0%).
65WGLF
Wicket gate automatic lock failure
A Indicates that the gate lock has not been fully applied on shutdown.
65M/LS
Manual control indication
I Provides remote indication that the governor is in manual control at the governor cubicle.
63QPV
Pilot valve strainer obstruction
A Alarm for attending strainer
49F Fire detection system operation/trouble
A,P Operation or failure of detection/ extinguishing system.
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BAL Governor balance
indication I For electric governors, indication of electric-
hydraulic transducer input voltage. Type
C = Control P = Protection trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
Table 5.2.2 – Control and Status Data Transmitted from Unit Control Switchboard
to Governor
Signal Description Type Notes
39 Creep detector
enable C Enables rotor creep detector after a fixed time
following application of brakes on shutdown.
15FR, 15FL
Speed reference raise /lower commands
C Typically relay or switch contact closures. If power reference also provided, speed raise/lower operable only off-line. Some installations may utilize input reference analog or digital signal rather than raise / lower commands.
65PR, 65PL
Power reference raise /lower commands
C Typically relay contact closures when unit on –line. Some installations may utilize input reference analog or digital signal rather than raise/ lower commands.
65GLR, Gate limit raise/lower commands
C Typically relay contact closures, route to reversing drive motor. Primary function of the gate limit (GL) is to limit the maximum opening of the wicket gates under operator control to prevent overloading the unit at the prevailing head. Other control and protection applications include:
- Pre- positioning GL to 0%prior to starting to permit controlled opening of the gates upon energization of the start / stop solenoid 65SS
- Raising GL to turbine breakaway gate position after energization of 65SS
- Rapid unloading of the machine during certain stop and protection shutdown sequences
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3SS On-off command to start/stop solenoid 65SS or gate limiter motor
C,P The start/stop solenoid 65SS typically operates as follows :
- Energized to allow wicket gates to open and close under control of the electric governor, gate limit or manual gate control, that is, “energized to start and run”
- De-energized to initiate complete closure of the wicket gates at maximum rate and block subsequent opening of the gates, i.e. “de-energized to stop”
Typical functions that will block start and/or initiate stop are
- Unit protection operation (includes all electrical and mechanical fault detectors that initiate shutdown of the unit)
- Operator-initiated stop - Generator thrust bearing high pressure oil
pump failed to achieve full pressure - Turbine shaft maintenance seal on or low
gland water flow. - Generator brake shoes not cleared or brake
air pressure not off, or both. - Intake gate not fully open - Generator and turbine bearing cooling water
not available. - Wicket gate lock not released
3SNL On/off command to partial shutdown (speed-no-load) solenoid
C,P The partial shutdown solenoid 65SNL (if used) is typically de-energized to limit the opening of the wicket gates, or return them, to a position slightly above the speed-no-load position and is controlled as follows :
- Energized when unit circuit breaker closes to allow generator to be loaded.
- De-energized whenever unit circuit breaker trips to restore unit to near rated speed; provides backup to the electric governor
- De-energized to unload the unit for certain protection operations (that is over speed to 112% during opening of unit circuit breaker)
V, I Generator
voltage and current
C Inputs to power transducer (for governors utilizing power feedback rather than gate feedback).
52 Unit on-line C Generator circuit breaker auxiliary contact. Used to switch between on-line and off-line gains in compensation circuits (PID) and to switch between
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speed and power references.
3AB Generator air brakes on/off command
C Air brakes automatically applied on shutdown if wicket gates close and speed below a predetermined level.
71NH Level difference between headwater and tail water
C Used for optimum turbine blade positioning and optimum gate position/ power generation.
Type C = Control P = Protection Trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication analog, digital, status lamps)
Table 5.2.3 – Operating Power, Air and Water from Service Equipment to
Governor
Description Type
Notes
Power supply for DC control DC One or more separate supplies depending on power distribution arrangement
Power supply for Oil Pressure Unit pumps
AC One or more separate supplies depending on number of pumps and required redundancy.
Alternate supply for governor power supplies
AC
Air supply for generator air brakes
A -
Air supply for Oil Pressure Unit
A
Cooling water for Oil Pressure Unit oil sump
W (Optional)
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Type AC = AC Power
DC = DC Power A = Air W = Water
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Table 5.3.1 – Control and status data Transmitted from Generator to unit control board
SIGNAL DESCRIPTION TYPE NOTES 26GS 38THT 38GT 38QB 26AO 26AI 26GF 71QBH 71QBL
Stator winding temperature Thrust bearing temperature Guide bearing temperature. Bearing oil temperature Air cooler outlet air temperature. Air cooler inlet air temperature. Generator field temperature. Bearing oil level high Bearing oil level low
T,A,P T, A, P T, A, P T, A, P T, A T, A T, A, P A A
Temperature detectors (typically 12) embedded in stator winding accordance with ANSI C50. 10-1977 (1). Two hottest RTDs connected to thermal overload relay 49G.
Temperature detectors embedded in wells in the shoes or segments with provision for interchanging sensors between segments. Temperature detectors. Provision for mounting sensors in all segments. Temperature detectors in bearing oil reservoir. Temperature detectors. (Quantity dependent on number of coolers and desired level of coverage.) Temperature detectors. (Quantity dependent on number of coolers and desired level of coverage.) Temperature monitoring system for continuously monitoring field temperature. One sensor for oil reservoir, equipped with direct reading visual indicator. One sensor for each separate oil reservoir, equipped with direct reading visual indicator.
38QW 39V
Bearing water contamination detector Bearing/shaft vibration detector
A A. P.
One sensor for each separate oil reservoir, for detection of water buildup or emulsified. Eddy current probes installed in guide-bearing segments at 90 degrees to each other, for detection of equipment defects and rough zone operation. Used in
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63QTH
Thrust bearing high pressure oil system start interlock/failure alarm.
C, A, I
conjunction with probes on turbine guide bearing. Pressure switch provides confirmation that the oil pump motor has established sufficient pressure to allow the start sequence to proceed. Used also to generate alarm if pressure fail to establish after pump is commanded to start.
26G 63FG 33AB CT-G 33CW or 80CW
Temperature detectors for fire protection system Fire extinguishing system operation Air brake position indication Neutral end and terminal end current transformers Cooling water valve position Cooling water flow low
P, C, A P, A C, I P, I C, I A, P
Fixed temperature or rate-of-rise of temperature or both; detectors mounted in stator end turn area. Used to initiate fire extinguishing system in conjunction with fault detecting equipment. Pressure switches installed downstream of actuating valve. Back trip generator protection. May also be used to generate an extinguishing system failure alarm if system is initiated but pressure fails to establish within a fixed time. Start interlock indicating all brake shoes have cleared runner plate. Furnished in quantities and ratings compatible with the metering and primary/standby protection requirements. Start interlock and status indication. Pump Failure, supply valve closed, pipe obstruction, pipe rupture
TYPE
C = Control P = Protection trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
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Table 5.3.2 – Control and status data Transmitted from Generator to unit controlbord
SIGNAL
DESCRIPTION TYPE NOTES
2THS 20CWS 20FGS 20AL 1GL
Thrust bearing high pressure oil pump start/ stop command. Generator cooling water system start/ stop command. Fire extinguishing system operate command. Air louver operate command Generator lube oil system start/stop command.
C C C, P C, P C
Start pump prior to starting unit. Confirmation of pump starting via 63QTH (Table 3A-1) Open valve or start pump prior to starting unit. Confirmation of water flow via 33CW or 80CW (Table 3A-1). Open valve upon detection of fault + excessive heat. Confirmation of valve operation via 63Fg (Table 3A-1). Close discharge and inlet air louvers in generator housing in event of a fire. Enables generator lubrication prior to unit run. When forced air cooling is used for the generator. Turned off when unit is on-line.
TYPE C = Control P = Protection trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
111
Table 5.3 .3 – Operating Power, Air and Water from Service Equipment
to Generator
DESCRIPTION TYPE NOTES
Power supply for thrust bearing high-pressure oil pump. Power supply for DC control circuits. Air supply for brakes and rotor jacking system Water supply for fire extinguishing system Power supply for generator housing space heaters. Water supply for generator air coolers and bearing oil coolers. Air supply for operating discharge and inlet air louvers Power supply for CO2 fire extinguishing system. Power supply for generator lube oil system.
AC DC A W AC W A DC AC
415 volts 3 phase AC. For uninterruptible systems such as air cooler temperature control system, fire protection. Control valve may be located in governor cubicle/ generator brake panel. May also be atomized. Thermostatically controlled, for reducing condensation on windings when generator is shut down. May be fed alternatively from DC source.
TYPE C = Control P = Protection trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
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Table 5.3.4 – Control and Status Data Transmitted from Generator Terminal Equipment to Unit Control Switchboard
Signal
Description Type Notes
CT Current signal for relaying and
metering
VT Voltage signal for relaying and
metering
A Current indication I
F Frequency indication I
V Voltage indication I
W/VAR Metering I,A Analog signals for
indication and/or recording.
AVR Voltage signal for automatic voltage regulator (AVR)
C Analog signal from a VT.
N Governor speed sensing C
XDCR Power transducer C Unit power input to electric governor.
TYPE C = Control P = Protection Trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication analog, digital, status lamps)
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Table 5.3.5 – Control and Status Data Transmitted from Unit Control Switchboard to Generator Terminal Equipment
Signal Description Type Notes
20 Fire extinguishing system command
C,P Deluge valve upon differential operation and high temperature detection.
TYPE
C = Control P = Protection Trip A = Annunciation/Event Recording T = Temperature Monitoring I = Indication analog, digital, status lamps)
Table 5.3.6 – Operating Power, Air and Water from Service Equipment to Generator Terminal Equipment
Description Type Notes
Power supply from DC control circuits DC For uninterruptible systems such as fire protection.
Power supply for forced air bus duct circulation system
AC
Water supply for fire extinguishing system and forced air cooling
W
TYPE
AC = AC Power DC = DC Power
A = Air W = Water
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Table 5.3.7- Control and Status Data Transmitted to and from the Cooling System and Unit Control System
Description Type Notes
Conventional
Fan failure A.P. Trip occurs on multiple fan failures resulting in insufficient air flow
Raw water low flow A Trip is accomplished by winding temperature
Strainer differential pressure
A
Type
A = Annunciation
C = Control
P = protective trip
T = temperature monitoring
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Signal Description Type Notes
51ET Exciter transformer o/c
protection
P
49 GF Field overload 1 Set to coordinate with field winding thermal
characteristic
I f Field voltage indication 1 Transuded from DCCT ( satiable reactor )
Vf Field voltage indication 1
64 F Field ground detection P or
A
27 FF Failure of preferred field
flashing source
A Provision of this alarm assumes 2 sources
provided AC and DC. AC should be
preferred source to minimize chance of back
feeding field voltage onto battery if blocking
diode fails. Automatic transfer to alternate
source on failure of preferred source
41/a,
41/b
Field breaker position C,I
31/1,
31/b
Field flashing contactor position I
48E Exciter start sequence
incomplete
P,A Set to operate after normal time required for
field flash source to build terminal voltage to
level sufficient for exciter getting to
commence.
78 E Pole slip protection P
63F-1 Cooling fan failure –Stage I A Failure of redundant fan (s).
63F-2 Cooling fan failure –Stage 2 P
27PS DC power supply failure P or
A
Trip or alarm depending on level of power
supply redundancy.
26ET-I Exciter transformer over
temperature –Stage I
A Indicating unit with dial contacts typical.
Table 5.4.1 – Control and Status Data Transmitted from excitat ion system to unit control switchboard
116
26ET-2 Exciter transformer temperature
–Stage 2
P
58-1 Rectifier transformer
temperature
A Thyristor fuse, conduction, or gating failure.
-
58-2 Rectifier failure –Stage 2 P
49 HE Heat exchanger failure A Various heat exchanger arrangements are
possible Once-through, closed system, etc
26RTD Exciter transformer temperature
indication
I Temperature detectors. Quantity variable
depending on number of secondary winding
and whether transformer is 3 phase or 3 x 1
phase.
70V Manual voltage adjuster with I Signal generated by potentiometer coupled to
70V motor drive.
70V/LSI,
2
70V End-of travel indication I Signal generated by limit switches coupled to
70V motor drive
90V Auto voltage adjuster with
position
I Same as 70V.
90V/LSI,
2
90 V End-of –travel indication I Same as 70V/LSI,2.
70V/LS3 70V preset position C Interlock in start sequence
90V/LS3 90V preset position C Interlock in start sequence.
89LS Station service A.C test supply
switch position
I Optional
MAN Indication mismatch between
auto
I To ensure bumpless transfer from AUTO to
AUTO Voltage regulator output and
manual
I MAN and MAN to AUTO
Balance Voltage setpoint
Balance Voltage setpoint
117
TYPE C = Control P = Protect ion Tr ip A = Annunciation /Event recording T= temperature Monitoring I = indication (analog, digital, status lamps)
Table 5.4.2 – Control and Status Data transmitted from unit control Switchboard to excitation
SIGNAL DESCRIPTION TYPE NOTES
41 protective trips
Field tripping from generator P
41 control Field breaker tripping from manual control and unit shutdown sequence logic
C
41 close Field breaker closing from manual control and unit start sequence logic
C
IE Exciter de-excite C Close contact to initate field flashing at 95% speed during auto start or under manual control
IE Exciter de-excite C Open contact to initiate phaseback below 95% speed, unit separated form system
83VT Voltage transformer potentil C Transfer exciter from auto voltage control to manual control
43AM Close contact transfer exciter to manual voltage regulator control
C
43VA Close contact to transfer exciter to auto voltage regulator control
C
70V Rum.
Back logic
Run 70V to preset position preparation for unit starting
C
90V Rum.
Back logic
Run 90V to preset position preparation for unit starting
C
70 V raise Raise manual voltage adjuster
C
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70 V lower Lower manual voltage adjuster
C
90 V raise Raise auto voltage adjuster C
90 V lower Lower auto voltage adjuster C
52G/a Generator CB Auxiliary switch
C De- excite control, disable power system stabilizer of-line.
Wicket gate position
Analog signal representing wicket
C Used to develop accelerating power input to PSS if required
TYPE
C = Control P = Protect ion Tr ip A = Annunciation /Event recording T = temperature Monitoring I = indication (analog, digital, status lamps)
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Table 5.4.3– Operating Power, Air and Water from Service Equipment to
Excitation system
DESCRIPTION TYPE NOTES
Station service as test supply AC Used for exciter testing and emergency
operation if exciter transformer out of service
(optional)
Battery-fed field flashing DC
Station service field flashing
source
AC AC preferred source. Auto transfer to dc if ac
not available
Cooling water supply for
heat exchanger
W
TYPE C = Control P = Protect ion Tr ip A = Annunciation /Event recording T = Temperature Monitoring I = Indication (analog, digital, status lamps)
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Table 5.5.1 – Control and Status Data Transmitted from Transformer to Unit Control Switchboard
Signal Description Type
Notes
CT Current signal for relaying and
metering
A, P, I
71G Gas accumulation detection A Event recording (optional).
63G Gas pressure device A, P Event recording
63Q Main tank sudden pressure relief
device
A, P Hand reset contact (local). Event recording
63T Main tank over pressure switch A, P Trip generator breaker
49-1W 49-2W
Transformer winding temperature thermal device in each separate winding
A, T, P Temperature detectors embedded in each separate winding for first stage temperature control. RTD are in each winding because of the possibility of unbalanced loading.
26Q Top oil temperature indicator A, T Dial type oil temperature indicator at the transformer. First stage annunciation, tripping optional. Second stage tripping
71QC Conservator tank oil level indicator A Dial type indicator with maximum and minimum indicating levels. Tripping optional.
Table 5.5.2 – Control and Status Data transmitted from Unit Control Switchboard to Transformer
Signal Description Type
Notes
20 Fire extinguishing system command
C, P Actuated upon differential relay operation or sudden pressure relief device. Fire detection sensors shut off the transformer fan and pumps
Type C =Control
P =Protection Trip A =Annunciation/Event Recording T =Temperature Monitoring I =Indication (analog, digital, status lamps)
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Table 5.5 .3 – Operating Power, Air and Water from Service Equipment to transformer
Description Type Notes
Power supply for DC control circuits
DC For uninterruptible systems such as fire protection.
Power supply for fans, pumps, ac control circuits
AC For FA, FOA transformers. If an FOW transformer is used, additional information and control signals may be needed, such as monitoring of the pressure difference between the oil and water systems.
Water supply for fire extinguishing system
W
Water supply for cooling W
Type AC =AC Power
DC =DC Power A =Air W =Water Table 5.6.1 – Signals Transmitted from Plant Equipment to Generator
Breaker Signal Description Type
Notes
4 Unit control C Normal shutdown
1XJ Breaker control switch, trip/close C
12G Generator overspeed P
25 Synchronizing equipment C
33 Wicket gate position switch C Permissive switch
38GB Generator bearing temperature P
38TB Turbine bearing temperature P
43XJ Breaker test switch C
49T Step-up transformer over temperature P
63T Step-up transformer sudden pressure P
71K Kaplan low oil P
80TBQ Turbine bearing oil P
38G Generator winding temperature P
43S Unit synchronizing selector switch C Permissive switch
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Table 5.6 .2 – Signals Transmitted from generator Breaker to Unit
Control Switchboard
Signal Description Type Notes
52a, b Breaker open-close C, I
27CB Generator breaker loss of dc control
power
A
61 Generator breaker pole failure P, A Trip is isolate breaker.
63a Breaker air pressure switch C Permissive switch.
63A Generator breaker low air pressure P, A
Type C =Control
P =Protection Trip A =Annunciation/Event Recording T =Temperature Monitoring I =Indication (analog, digital, status lamps)
Table 5.7 – Intake Gate/MIV and Draft Gate Controls for automatic operation of the Intake gate shall as follows: 1 Unit Control Board • Raise/lower control switch
• Indicating lights for fully open/fully • Position indication showing actual position
of the gate 2 Local • Raise/lower control switch
• Mechanical device showing gate position 3 Annunciation • Failure of gate to open or close in response to
an automatic signal • Failure of gate to maintain partial closure
position during sluice operation • Hydraulic system trouble
Table 5.8 – Canal/HRC Water Level Signal for Governor Control
S. No. Description Type Notes
1 Breaker open-close C, I,P
2 Generator breaker loss of dc control
power
C,I
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5.4 MANUAL CONTROL, METERING AND PROTECTION SYSTEM 5.4.1 Scope of Supply and Design Criteria
Design, manufacture, testing, commissioning of manual control, metering and protection system which includes Electrical protection by conventional relay; manual control and metering of the Power House.
5.4.2 Standards
All materials and equipments shall comply in every respect with the requirements of the latest edition of the relevant Indian, British equivalent N.E. M.A. I.E.C. Standards or any other recognized International standards, except in so far as modified by this specification. Where standards offered are other than the Indian or British standards, copies of the relevant standard specification in English language must be attached.
5.4.3 Design Criteria
The control will have provision for start, stop, manual synchronizing and emergency stop. Sequencing will be as following tentative Drawings (to be enclosed by Purchaser).
• Start Sequence for synchronous generator • Normal Stop and Mechanical Trouble Stop Sequence for
Synchronous Generator • Electrical Trouble Stop Sequence for Synchronous Generator
Final drawings will be submitted for approval by the Purchaser 5.4.4 Protection and Metering Scheme
Requirements of metering and protection/scheme and the function performed by various relays are explained in following tentative drawings (to be enclosed by Purchaser). i. Single Line Diagram Main ii. Metering and Relaying Single Line Diagram (sheet 1 of 2) iii. Metering and Relaying Single Line Diagram (sheet 2 of 2) iv Unit tripping and annunciation block diagram Common tripping relays for similar functions have been provided with lock-out facilities. All these relays shall have potential free contacts for trip and alarm purposes and externally hand reset type of flag indicators. They should preferable be housed in drawout type of cases with tropical finish. All the protective equipment will be housed in the Power Plant main control room. The details of C.T.’s for all the unit protection and metering are given in Drawings
124
No. ----. The secondary current of C.T.’s located in switchyard is proposed as 1 amp. because of long leads so as to ensure efficient and accurate operation of their protective scheme. 11 kV C.T.s and P.T. may be mounted on 11 kV switchgear panels alongwith relays. The drawings for the proposed system will be subject to approval by the Purchaser.
5.4.5 Protective Relays
A brief description of protective relay proposed is given below: 5.4.5.1 Generator Protection
Generator Differential Protection (87G)
The generator primary protection is proposed by high impedance type of circulating current relays having proper setting range. The relays will be of high speed type and shall be immune to A.C. transients. Necessary provision shall be made in the relay to ensure that the relays do not operate for faults external to the protected zone. The relays shall not maloperate due to harmonics in spill current produced by through faults or due to saturation on one set of current transformers during an external fault. Provision shall also be made for alarm /indication in case of current transformer secondary circuit fault.
The relay operation actuates lockout relay for complete shutdown of the unit including release of CO2 as shown in Drawing No. ----.
Generator ground fault protection (64G)
The generator neutral will be earthed through the primary winding of a distribution transformer of proper capacity and ratio. The secondary will be loaded by a suitable resistor rated for 60 seconds. A suitable voltage relay with continuous coil rating with proper setting is proposed to be provided. The relay shall be insensitive to voltage at third harmonic frequencies.
The relay operation actuates lockout relay for complete shutdown of the unit.
Neutral Grounding Transformer and Loading Resistor
Neutral Grounding Transformer a. Type Dry type, Natural air cooled,
125
single phase. b. Connection Between generator neutral
and ground Loading Resistor a. Construction Non-ageing, corrosion
resistant, punched stainless steel grid elements provided with necessary installations, and temperature rise not exceeding 300 deg. C.
b. Housing Enclosure with IP:22 degree of protection. However, transformer and resistor can be housed in same container with metallic partition.
Generator over-voltage protection (59)
A set of single phase relays is proposed with suitable time delay setting so that operation of relay under transient conditions is avoided. The relay setting range is proposed from 110% to 150%. The relays shall be immune to frequency variation. Provision of instantaneous tripping element at some suitable setting is also proposed.
The relay is set to operate lockout relay for partial shutdown to speed no load position.
Negative phase sequence current protection (46)
A two stage protection complete with filter network is proposed for this purpose. The first stage with a lower suitable range shall be instantaneous and shall be arranged to give alarm and annunciation and the second stage with higher range will energise a timer which shall perform the various tripping functions in two stages at different time settings, as shown in the drawing E-230-3. The current transformer for this protection is proposed to be located on the generator line side.
The relay is set to operate the lockout relay for partial shutdown to speed no load position.
Voltage restraint over current protection (51V)
This backup protection for the generator operates for over current which are accompanied by dip in voltage so that false tripping due to through faults are avoided. The relay is set to trip lockout relay for partial shutdown to speed no load position.
126
Reverse power relay (32)
This relay is proposed because of grid connection. The relay is proposed to be set to trip lockout relay to speed no load position. Check Synchronising relay (25)
Check synchronising relay is provided to ensure the closing of the circuit breakers on synchronising at a phase angle not greater than about 7 degrees so as to prevent damage to circuit breaker especially in case of auto synchronising.
Potential transformer fuse failure protection (60)
Suitable voltage balance relays are proposed to monitor the fuse failure of 3 sets of potential transformers and to block the relays (50/51 V or 40) or other devices that may operate incorrectly on the voltage due to fuse failure of potential transformers. The relay is set to give an alarm only.
Mechanical Protections
Following mechanical protections are proposed for the generator:
j. Resistance temperature detectors in stator core (12 no.) and in the
bearings for indication, alarm and recording. RTD’s are to be provided by Generator Suppliers.
k. Turbine and generator bearing, metal and oil temperatures – alarm/shutdown.
l. Governor oil pressure low to block starting and low-low for emergency tripping.
m. Over speed for normal and emergency shutdown depending upon its extent.
n. Signal to canal regulating gates to avoid channel overtopping due to emergency shut down of unit.
o. Contractor will co-ordinate with Generator and Turbine supplier for mechanical protection.
5.4.5.2 Exciter Protection
Generator field failure protection (40)
An offset mho type of relay having its circular characteristics adjustable both in offset and diameter, along the X-axis of the R-X plane, is proposed for this purpose.
127
The protection shall consist of two stages. The first stage with a lower range shall be arranged to give alarm and annunication. The second stage with a higher range shall carry out the tripping functions as shown in the Drawing --. Generator rotor earth-fault protection (64F)
Direct current injection type of protection is proposed for this purpose. The relay will be suitable for the field system voltage and be capable of detecting deterioration of insulation level below about 0.2 Mega-ohms. 110 Alternating current potential transformer auxiliary supply will be available but the relay will have its own internal rectifiers etc. to drive the D.C. injection supply. Failure of A.C. auxiliary supply will not totally incapacitate the protection. The tripping of the relay is set to open the excitation breaker and bring the unit to speed no load.
Over current relay (51 EX)
This over current instantaneous relay in the excitation circuit before the excitation transformer will cater to rectifier transformer faults and other excitation system faults. This relay is set to trip excitation circuit breaker and bring the unit to speed no load.
Over excitation relay (OER) in the DC circuit and excitation relay (31) in the field flashing circuit are other relays proposed in the excitation system.
5.4.5.3 Station Service System
Over Current Protection (51)
Suitable relays are proposed to be provided for unit auxiliary transformers over load protections. The relay will operate from the three current transformers on the Low Voltage side of the transformer and will be arranged to trip the Low Voltage breaker as shown in the Drawing E-230-3.
An instantaneous time over current relay is proposed from the CT’s on the 11 kV side of the auxiliary transformer. This relay at a higher setting will cater to transformer faults and the tripping of the relay is set to bring the unit to speed no load as shown in Drawing E-230-5.
Phase sequence relay (47) This relay on the station service system trips the LV circuit breaker so as to prevent operation of the three phase motors in the reverse direction (Refer Drg. -----).
128
Under voltage relay (27)
These relays have been provided to trip the LV circuit breaker (Refer Drg. -------).
5.4.5.4 Step up 11/---- kV Transformer Protection
Generator Transformer Differential Protection (87 GT)
A sensitive percentage biased differential relay is proposed to be provided for each step up transformer protection with proper operating and bias setting. It shall have harmonic restraint feature to prevent its mal-operation due to magnetising in-rush surges encountered in normal power system operation. Provision shall also be made for alarm/indication in case of current transformer secondary circuits faults.
The C.T.’s on 11 kV side are proposed be located in the Generator neutral side and on ----- kV side in the switchyard. The auxiliary/interposing current transformers as required for the protection shall also be provided.
The relay is set to operate lockout relay for shutdown as shown in Drawing No.-----.
Standby earth fault protection (64T)
For this protection Inverse Definite Minimum Time Lag type relay having suitable setting range and operating time is proposed. The relay shall be energized by zero sequence current supplied to it through current transformer in the power transformer neutral. This relay is proposed to trip the unit circuit breaker and bring the unit to speed no load. The relay will be co-ordinated with line earth fault protection.
Bucholz gas pressure relay for first stage alarm and second stage trip.
Transformer oil level and temperature
Winding temperature
5.4.5.5 ----- kV – Bus Bar Protection
Bus zone Differential Protection (87 B1, and 87 B2) A high speed, high impedance type bus-bar differential protections proposed to be provided for each ---- kV bus zone. The scheme shall have separate and independent check and supervision features incorporated in it. Necessary separate C.T. cores shall be provided at the incoming and outgoing
129
circuits for check features. The main zonal relay and check relay scheme will have their contacts connected in series in the trip circuit.
The protection will be capable of detecting all type of faults on the bus-bar. The sensitivity of protection shall be such that it does not operate for faults on the C.T. secondary wiring of the most heavily loaded circuit. C.T.’s on one side of the bus coupler/section breaker are proposed and inter-locked overcurrent relay will be provided.
The supervision relay will be capable of detecting open: Cross or broken C.T. secondaries and pilots by employing sensitive alarm relay, which shall be connected across the bus wires of each protected zone. It shall be capable of taking the protection of the effected zone out of service by shorting the appropriate bus-wires.
`No volt’ relays to indicate failure of D.C. alarm and trip supply to the bus-bar protection scheme is also proposed to be provided.
High speed tripping relays shall be provided to trip the connected circuit breakers
connected to the faulty bus bar.
5.4.5.6 --- kV Line Protection
Protective relay design for the --- kV line is important because of high fault power from 66 kV grid sub-stations. Main features of fast acting protection system are tentatively proposed as follows:
i) Main- Phase comparison static carrier relay (185) ii) Backup- Directional overcurrent and ground fault (51 D) iii) Local backup- Backup protection (FPR) iv) Separate current transformers for two main protections. v) One potential device per phase has each line with separate secondary winding
(independently fused) for primary and back up relay. vi) Separately fuse D.C. tripping with separate auxiliary tripping relay. vii) Provision of local back up protection for failure of Main and back up relay and
on breaker failure. Following Relays are provided. 5.4.5.7 Under voltage relay (27)
Under voltage relay shall be provided on the line and the bus to indicate live line
conditions. Relays with separate flush/semi-flush drawout cases and having individual
in-built testing facilities shall be preferred. But modular drawout construction and
equivalent facilities would also be accepted. The panels shall be complete and all
necessary name plates, device identification, terminals blocks, fuses etc. shall be
provided.
130
The protection requirement with respect to characteristics operating principle, tripping schedule and type of relays shall be discussed during detailed engineering stage, and Bidder shall provide the same to the satisfaction of the Owner.
5.4.6 Metering
Meters as shown in Schematic drawing (to be enclosed by Purchaser) shall be provided on unit control boards. These are summarised below:
5.4.6.1 Generator (Unit Control Board)
vii. 3 ammeters (each phase) viii. Power factor and kW meter ix. KVAR x. Voltmeter with voltmeter switch xi. KWH meter
5.4.6.2 Auxiliary Transformer
iii. kWH meter iv. Ammeters (3 No.)
5.4.6.3 Bus Coupler Panel
No Metering is required on this panel . 5.4.6.4 ---- kV Feeder Panel
v. Voltmeter with voltmeter switch vi. 3 Ammeters (each phase). vii. Recording kVAR (MVAR) viii. K.W. v. Power Factor meter
vi. kWH import / export meter.
5.4.7 Annunciation
Conventional 16 window annunciator for each generator turbine faults; 12 window each for feeder faults and Bus Coupler is proposed for important faults. Schedule for these windows may be proposed for approval by purchaser. All other annunciation will be on SCADA system.
5.4.8 Recorder All recording will be done on SCADA disk. 5.4.9 CTs/VTs and General Surge Protection Equipment 5.4.9.1 All current and voltage transformers required for protection system of the unit are
detailed in generator specifications shall have adequate VA burdens, knee point
131
voltage, instrument safety factor and characteristics suitable for the application, and shall be subject to approval of the Owner. Details of --- kV(Feeder) CTs are to be given by the Purchase .
CTs/VTs used for different applications shall have following accuracy class: a) Differential protection CTs Class PS b) Protection CTs other than differential protection Class 5P10 c) Generator AVR/metering CTS for generator circuit Class 0.5 d) Metering CTs for --- kV; 11 kV and 415 V switchgear Class 0.5 e) CTs for performance testing and low forward power Relay Class 0.2 f) Core balance CTs Class PS g) Protection VTs Class 3P h) VTs for generator metering, AVR synchronisation Class 0.5 i) VTs for performance testing and low forward power relay Class 0.2 List of all CTs and PTs is enclosed in these specifications.
5.4.9.2 Generator Line Terminal and Neutral Grounding Cubicles
These shall be provided as per detailed given in generator specifications. 5.4.9.3 ---- kV (feeder) Current Transformers and Potential Transformers
They will be provided as per detailed specifications of switchyard equipment. 5.4.9.4 The technical requirement and location of the CTs are given in the unit metering and
relaying drawing (enclosed). The generator suppliers shall supply suitable current transformers for the protection scheme and these shall be in the neutral grounding cubicles.
The current transformers should be suitable for metering and protection scheme attached . 11 kV CTs are as detailed below.
11 kV Current Transformers
1 11 kV Current Transformers of ratio 600/5A. (a)Generator neutral side – Three core -6 Nos. Core 1 PS class for differential protection relay 87G. Core 2 5P10 class for General protection relay i.e. 32,40,46,51V.
Core 3 PS Class for Differential Protection relay of
132
Generator Transformer 87GT with three Nos.
interposing CTs
.
(b)Generator Transformer side – Two core -6 Nos. Core 1 Class 0.5 for AVR. Core 2 Class 1 for metering.
2 11 kV CT ratio 600/5A in 11 kV cubicle – 6 Nos.
Single core PS class for Differential Protection of Generator 87G relay.
3 11 kV CT 11kV cubicle - 6 Nos.
(Ratio to be decided after capacity of Rectifier Transformer decided)
Single core 5P10 class for over current protection of Rectifier Transformer circuit 51EX relay .
4 11 kV CT ratio 30/5A in 11 kV cubicle – 6 Nos.
Single core 5P10 class for over current protection of Unit Aux. T/F
50/51 relay.
5.4.10 Control Panel Layout
Layout of Control panel is shown in enclosed drawings
5.4.11 Details of Control and Relay Panels
5.4.11.1 Generator transformer control and relay panels
Floor mounted, sheet steel simplex type control and relay panels with the following equipment mounted on them shall be supplied for Generator Transformer control and protection.
Control panels
133
S. No.
Nomenclature
Quantity Description
1. - - Mimic diagram of bus –bars and connections. 2. BI 1 set Semphore indicators for isolators. 3. CB 1 set Semphore indicators for circuit breakers. 4. AG 3 Nos. Dial type A.C. ammeters for measuring
generator current in Amperes range 0-800A 5. VG 1No. Dial type A.C. voltmeter for measuring
generator voltage in kV range 0-15 kV 6. VS 1No. Voltmeter selector switch. 7. PF 1No Polyphase indicating power factor meter
range – 0.5 to 0 to +0.5 8. KW 1 No. Polyphase indicating kW meter of range 0 to
15000 kW 9. KVAR 1No. Polyphase indicating KVAR meter of range
0-6000 kVAR 10. FM 1 No. Frequency meter 0-75 Hz 11. AF 1 No. Field current meter 0-200 A 12. VF 1 No. Field voltage meter 0-300 V 13. SI 1 No. Speed indicator 0-1000 rpm 14. SL 1No Gate limit indicator 15 SW 1 no. Remote/ local selector switch 16. A/M 1 No. Auto/manual selector switch 17 S1 1No. C.B. control switch with indicating lamps
including healthy trip supply indication. 18 S2 1 set Bus Isolator control switch with indicating
lamps 19 S4 1No. Gate limiter control switch (Raise/lower ) 20 S5 1 No. Speed level control switch (Raise/lower).
21. SS 1No. Synchronising switch with locking key 22. T 1 No. Temp. indicator with selector switch 23 86 G 1 No. High speed tripping relay 24 30 X 1No Emergency stop switch with cover 25 30 Y 1N. Stop reset push Button 26. KWH 1 No. Energy meter with test block
1 Set Annunciation block with 16 windows complete with alarm cancellation lamps reset and lamp test push buttons
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Relay panels
S. No.
Nomenclature
Quantity Description
1 87 G 1 Set Tripple pole generator differential protection relay including auxiliary relay etc.
2 50/51T 1 No. Overcurrent Earth fault relay for Generator transformer.
3 51 V 1 No. Backup protection relay ( over current voltage restraint.
4 64 G 1No. Generator ground protection relay. 5 64T 1No. Transformer ground protection relay 6 59 1No Over voltage relay 7 25 1 No. Check synchronising relay 8 32 1 No, Reverse power relay 9 46 1No. Negative phase sequence relay 10 40 1 No. Field failure relay 11 87 GT 3 Set. Generator Transformer differential protection
relay including auxiliary relay etc. 12 64 F 1No. Rotor earth fault relay 13 12 G 1No. Over speed relay (electrical) 14 27 1No. Under voltage relay 15 47 1No. Phase sequence voltage relay 16 84 1No. Generator trip relay 17 Auxiliary and locking relays
5.4.11.2 -- - kV feeders control and relay panels
Floor mounted, sheet steel simplex type control and relay panels with the following equipment mounted on each of them shall be supplied for Mukerian stage I and Dasuya feeders control and protection.
Control panels
S. No.
Nomenclature
Quantity Description
1. - - Mimic diagram of bus –bars and connections. 2. BI 1 set Semphore indicator for Bus isolators. 3. LI 1N0. Semphore indicator for line insulator 4. CB 1 set Semphore indicators for circuit breakers. 5. A 3 Nos. Dial type A.C. ammeters for measuring feeder
current in Amperes range 0-200A 6. V 1No. Dial type A.C. voltmeter for measuring
voltage in kV range 0 to------kV 7. VS 1No. Voltmeter selector switch. 8. KW 1 No. Polyphase indicating kW meter of range 0 to
---------kW
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9. KVAR 1No. Polyphase indicating KVAR meter of range 0 to------ kVAR
10. S1 1No. C.B. control switch with indicating lamps including healthy trip supply indication.
11. S2 1 set Bus Isolator control switch with indicating lamps
12. S3 1set Line Isolator control switch with indicating lamps
13. SS 1No. Synchronising switch with locking key
14. 86 G 1 No. High speed tripping relay
15. KWH 1 No. Export/ Import Energy meter with test block
16. 1 Set Annunciation block with 16 windows complete with alarm cancellation lamps reset and lamp test push buttons
Relay panels
S. No.
Nomenclature
Quantity Description
1. 51D 1 No. Directional overcurrent Earth fault relay 2. 27 1set Under voltage relay 3. 185 1set Phase comparison relay 4. 81H/L 1 set High / Low frequency relay 5. Auxiliary relays as per actual requirement.
Other protections relays as decided by feeder protection designer .
5.4.11.3 Bus Coupler control and relay panel
Floor mounted, sheet steel simplex type control and relay panels with the following equipment mounted there on shall be supplied for Bus Coupler control and protection.
Control panel
S. No.
Nomenclature
Quantity Description
1. - - Mimic diagram of bus –bars and connections. 2. BI 2 sets Semaphore indicators for isolators. 3. CB 1 set Semaphore indicator for circuit breaker. 4. AB 3 Nos. Dial type A.C. ammeters for measuring
current in Amperes range 0-500A 5. S1 1No. C.B. control switch with indicating lamps
including healthy trip supply indication. 6. S2 A/B 2 sets Bus Isolator control switch with indicating
lamps
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7. 86 G 1 No. High speed tripping relay 8. 1 Set Annunciation block with 16 windows
complete with alarm cancellation lamps reset and lamp test push buttons
Relay panel
S. No.
Nomenclature
Quantity Description
1.-- 87 B1/B2 2 Sets Triple pole Bus Bar differential protection relay including check and auxiliary relays etc.
2. 51 I No. Interlocked overcurrent relay 3. Other Auxiliary relays as per requirement
7.4.11.4 Synchronizing Panel
Sheet steel swinging panel mounted on the side of the switchboard complete with internal wiring connections equipped as synchronizing panel with the following equipment mounted there on.
Quantity Description 2 Nos. Dial type A.C. voltmeter of suitable range for measuring
voltage in kV. 2 Nos. Dial type frequency meters of suitable range. 1No. Synchro-scope. 1No. Synchronizing lamps control switch (ON/OFF) 2Nos Synchronizing lamps. 1 No. Synchronization selector switch (Auto / Manual). 5.4.12 Test Blocks
Test blocks shall be provided on switchboards whore test facilities are required but are not provided by use of drawout type meters or relays. The test blocks shall be of the back connected semi-flush mounted switchboard type with removable covers. All test blocks shall be provided with suitable circuit identification. The cases shall be dust tight. Test blocks shall be rated not less than 250V. at 10 amps and shall be capable of withstanding a di-electric test of 1500 V, 50c/s for one minute. All test blocks shall be arranged to isolate completely the instruments or relays from the instrument transformers and other external circuits so that no other device will be affected and provide means for testing either from an external source of energy or from the instrument transformers by means of multiple test plugs. The test blocks and plugs shall be arranged so that the C.T. secondary circuits cannot be open circuited in any position , while the test plugs are being inserted removed.
5.4.13 Factory Tests for Unit Control Switchboards
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12. Review front and rear elevations versus the final approved drawings. Check each
item of equipment for proper location and verify the instrument/catalog number is correct per the specification.
13. Review the interior of the UCS in the same manner as the elevations. In addition, verify the lighting is adequate and grounding connections are provided.
14. Check anchor channels and cable entrances. Confirm they are in accordance with the drawings.
15. Review test certificate or witness the insulation resistance test of all wiring, current transformers, and potential transformers.
16. Check approximately 5 to 10 percent of the internal cabling. Verify that the following items conform to the drawings : • Cable numbers; • Terminal block designations; • Terminal designations on individual components such as control switches
and lockout relay; • Raceway layouts; and • Equipment identification nameplates.
17. Activate all protective relays. Confirm that the appropriate lockout relay is
energized and the correct annunciation and/or printout occurs. 18. Confirm that settings of all protective relays are in accordance with approved
documents. 19. Check all annunciation points. 20. Check factory calibration of all devices possible, including electronic speed
relays, current and potential transformers, and vibration monitors. 21. PLC checks:
• Check the I/O racks for type and number of analog and digital I/O cards; • Check for future expansion capabilities on the I/O racks; • Check for surge protection provided on the I/O rack and I/O cards; • Identify grounding connections for the PLC and the I/O rack; determine
whether chassis and logic grounds are the same or separate (this will affect the type and quantity of external surge protection required);
• Review the PLC ladder diagram viewed on the video display terminal versus the final approved PLC software coding documentation; and
• Verify that modem connections are provided and functional.
22. Perform the function checks listed below with the final approved schematics, PLC software coding, and control block logic diagrams in front of you. All premissives and interlocks should be provided by using the “dummy” toggle switchboard to provide these inputs. • Manual start/stop sequence (does not apply to redundant PLC control
schemes); • Auto start/stop sequence; • Manual emergency stop sequence; • Automatic emergency stop sequence (usually performed by activating one
of the lockout relays while in the “normal running” mode );
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• Change position of all control switches as follows (typically done while in the normal running mode);
- Local control to remote control - Remote control to local control - Manual control to automatic control - Headwater level control “OFF” to “ON” - Headwater level control “ON” to “OFF” - Excitation manual control to excitation automatic control - Excitation automatic control to excitation manual control; and
• Verify the performance of the automatic synchronizing circuit and the manual sync-check relay (if provided).
5.4.14 Field Tests for Unit Control Switchboards
10. Verify tags on all factory-calibrated instrumentation devices. 11. Check all external interconnection wiring against the approved power
house/equipment drawings, verifying the following items : • Cable numbers and type; • Terminal block designations; and • Raceway layouts
12. Perform point-to-point continuity and megger tests on all external cabling. 13. Calibrate all remaining instrumentation devices. 14. “Bench test” all protective relays to ensure proper settings. 15. Perform functional checks tests on all unit and station auxiliary equipment
controlled from the UCS to verify proper operation. 16. Perform functional checks on unit start/stop sequences, duplicating the factory
sequences. These checks should be performed first with the associated power circuits de-energized, and then with both power and control circuits energized.
17. Methodically document steps 1 through 7 to ensure that no cables, instrumentation devices, protective relays, or control systems have been overlooked.
18. Water-up the unit and perform all start/stop sequences. 5.5 SUPERVISORY CONTROL AND DATA ACQUISITION (SCADA) SYSTEM 5.5.1 Scope of Supply and Design Criteria
Design, manufacture, testing, commissioning of the Supervisory Control and Data Acquisition (SCADA) system which includes all equipments required for measurement, control, metering protection data logging data recording, annunciation and sequence of event recorder, main computer, display unit with keyboard.
The SCADA system required should provide monitoring of parameters listed in section 7.0 and control in grid mode and isolated mode operation of the Hydel Power
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station centralized control room at EL 246.0 m. It should also provide remote monitoring and control of the Power House from Mukerian stage I power house 7 km from this power plant. through dedicated fibre optic cable and redundant power line carrier communication (PLCC) system. This SCADA system should have following features:
♦ Reliable safe control of the unit with very high availability ♦ Automatic startup, on-load control and shutdown of the units by the control
system ♦ Control of auxiliary equipment ♦ Remote monitoring of all plant status and alarm information ♦ Remote normal startup, on-load control and shutdown of units by operators.
SCADA system should have following controllers
♦ Unit Controller. ♦ Common Plant Controller/Supervisory Controller at Power House control
room ♦ Remote Supervisory Controller
The SCADA system where it is proposed to be set up in this specification shall be designed for safe, reliable, efficient and easy operation of Hydro Turbine Generator and its associated auxiliaries and transmission lines.
The SCADA system shall consist of a redundant microprocessor based computer system, a dedicated sequence of events recording system, a health/condition monitoring and analysis system, system cabinets, local panels, sensors, local instruments, erection hardwares, interposing relays etc.
The SCADA to be supplied shall be of proven design; operation in at least six power house for more than 5 years and will be subject to approval by purchaser and will consist of following.
(i) Main microprocessor based computer system. (j) Modem and Communication system (k) Data logger/sequence of events recorder. (l) 19” colour graphic monitors with key boards (m) System console (n) Hard copy plotter/printer (o) Complete field instruments like transmitter/transducers, sensors, interposing
relays, erection hardwares all interconnecting cables etc. (p) Bidder shall supply all necessary software required for the SCADA system
including operating system, compiler, application software etc. (q) The transducers required for the measurement of electrical parameters. The
output of transducers will be 4-20 mA.
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The SCADA system shall be capable of performing the following functions in real time.
o) Acquire data from primary sensors. p) Process and retain data for each primary sensor. q) Perform detailed thermal and vibration analysis. r) Report machine performance in tabular and graphical format. s) Trending of turbine and generator efficiencies t) Sequence of even logging. u) Supervisory control of auxiliaries, governing system, excitation system, circuit
breakers, including synchronising. v) Display software including system monitoring alarm processing and display of
data, fault, and status of devices. w) Application software including state estimation, bad data detection, and on
line power flow. x) Data logging and report generation. y) Report alarms. z) Predict need for shut down and maintenance of equipment. aa) Software shall be such that the monitoring system will take care of the
transient parameters during system run-up and shut down. bb) Software shall be modular and upgradable. cc) The SCADA software shall run in co-ordination with existing/proposed
SCADA software for gate control operation. It can received data of Gate positions etc. from it and send generation etc. data to it.
5.5.2 Applicable Standards
1. I.E.E.E. - 1010 - 1987 2. I.S.O./I.E.C. - 12119 3. Applicable National and International standards for software & hardware
which will be listed. All proposals should clearly indicate which of sub-sections of the above
standards is complied with, if any. 5.5.3 Response Time
Fast response time of computer system is required. Bidder will intimate following: (d) Time duration required to update a graphical display from the instant a field
contact changes state. (e) Time duration from the instant a control is activated at the operator station
until the command is implemented at the field device. (f) Overall time duration to process and lag an alarm once it is received at the
computer.
Methodology by which these “times” were verified must be given. Acceptable time shall be verified at the factory acceptance test.
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5.5.4 Equipment Architecture and Protocol
Open architecture system shall be followed. Interface or operating standards for the following shall be intimated and should comply with ISO/IEC 12119. Communications Operating system User Interface Data base Each of these elements should be capable of being replaced by or communicate with system elements provided by other vendors.
5.5.5 Plant Operation Philosophy
The normal, start-up, shut down and emergency operations of the hydro turbine generator, auxiliaries and feeders shall be performed in three different ways as follows:
(j) Redundant PLC based governor control panel for unit and plant control (iv) Remote Control from Power House control room (v) Manual control panel The Control Engineer shall be able to perform the following operations from the CRT through keyboards.
f) Call up mimic, alarm, data display. g) Call up control display to carry out control operations for hydro turbine
generators and its associated auxiliaries and main & electrical power supply systems controlled from CRT/key board.
h) Demand, logs, report including performance calculation reports, summaries, trends and plots for hydro-turbine generator and its auxiliaries and main & auxiliary electrical power supply system.
i) The control engineer shall be able to set up all pre-start check of devices from the CRT/keyboard for unit starting such as :
7) The wicket gate control 8) The control of generator brakes 9) Power supply to the governor 10) Load/frequency device selection on speed setting mode. 11) The selection of speed droop equal zero. 12) The blades at fully open position etc.
j) The control engineer shall be able to set the interlocks to start the unit from the
CRT/key board and once the start command is given following sequence shall take place through the SCADA system.
1) Level control shall be put off. 2) The governor pump shall start.
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3) When the oil pressure is established in the governor circuit, blades shall set at the starting position.
4) Release generator brakes. 5) After having ensured that the bakes are released and blades are in starting
position command shall be given to open the wicket gates. 6) With opening of wicket gate unit speed shall rise. 7) At 90% unit speed, generator shall be excited, wicket gate shall be stopped
and its position maintained by energizing governor relays speed adjustment, blades/movements shall be achieved.
8) When unit frequency and phase voltage is matched to that of existing power system, unit circuit breaker shall be closed.
9) After unit breaker is connected to the system, governor parameters shall be set to automatic mode.
f) The control engineer shall be able to shut down the unit during normal condition in
the following sequence. . 1) Level control on governor shall put off 2) Blades shall close 3) When blades are closed, wicket gate shall be allowed to close. 4) When no output power is sensed unit breaker shall be tripped. 5) After unit breaker is open, blades shall open again. 6) When down stream gate is closed and unit speed is 30%, brakes, shall be
applied. g) The control engineer shall also be able to trip the unit during emergency condition
with the following sequence. . 1) Unit breaker shall be tripped. 2) Wicket gate shall be closed. 3) Other sequence of operation as per the normal shut down. 5.5.6 Parameter to be monitored from SCADA The SCADA system shall be complete with all primary sensors, cables, analyzers/
transmitters, monitors, system hardware/ software and peripherals etc. to monitor/ control the parameters for control, protection, annunciation, event recording etc different equipments detailed in 7.1 and including.
• Generator stator and rotor winding temperatures. • Lube oil temperature • Radio frequency interference • Generator air gap monitoring. • Status of generator coolant condition. • Acoustic levels • Vibrations • Flow measurement. • Turbine efficiency. • Cavitation of turbine blades • Level measurement
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• Turbine blade tip clearance • Governor control monitoring of turbine speed. • Generator terminal voltage, current, KW, KVAR, KVA, KWH,
Frequency, power factor, field voltage and field current. • Annunciation for violation of permissible limits of the above
parameters. • Turbine bearing temperature. • Guide bearing temperature. • Guide bearing oil level. • Guide vane bearing oil temperature. • Generator bearing temperature. • Generator winding temperature. • Turbine speed. • Generator speed. • Governor oil pumps, oil pressure indicator and low pressure switch. • Cooling water pumps, suction and discharge pressure switch/ gauge. • Inlet pressure gauge at inlet of turbine. • Vacuum gauge for draft tube pressure. • Level indicator for level in the forebay. • Weir type flowmeter for measurement of flow.
• Annunciation Bidder shall provide suggestions relating to measurement points and sensors. If in his
opinion, an enhancement in condition monitoring capability can be attained by use of additional sensors these should be provided and details to be indicated in the bid.
5.5.7 Hardware Requirement
The key hardware features of the controller should be as follows:
♦ Standardized hardware technology ♦ Highly modular design ♦ Expandable ♦ Operation over a wide voltage range ♦ Intelligent I/O modules ♦ Central and distributed I/O ♦ Communication with other controllers and computers ♦ Remote fault diagnostics
It should include all transient suppression, filtering and optical isolation necessary to operate in a power plant environment. The type of controllers to be used in the SCADA system should be selected to meet specific plant requirements described below including availability, number of plant I/O, cycle time and type of communications link. The modular design of the controllers should be such that they are easily integrated into the control system requiring the minimum of engineering.
5.5.7.1 Unit Controller
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Redundant microprocessor based/PLC based governor system control should be interfaced with SCADA powerful enough to perform all the required functions mentioned above. It should have capability to implement closed loop PID function for governing. The scan time of the complete sequence for each process should be less than 100 msec. It should have lock to prevent unauthorised modification and be capable of detecting hardware and software failures. It may also have digital relays for over current, over-voltage and differential generator protection. It should have following hardware features. It should have a console and keyboard to program the controller as well as communicate with Supervisory controller. Unit controller should support remote management and remote programming for supervisory controller.
5.5.7.1.1 Shut down Hardware
The controller should have a conventional relay logic shutdown circuit. This circuit should include start and stop relays for controlling the turbine. The start relay circuitry should provide for auto and manual control capability. A controller fail relay should drop out the start relay when the auto relay is on. All shutdown hardware should be powered by the station battery. The stop relay should drop the start relay whenever a contact input which is strapped for shutdown on a digital input module is closed.
5.5.7.1.2 Digital Status And Alarm Inputs
The controller should be capable of connecting to at least 60 contact type inputs representing digital status and alarms. All contact inputs should be sensed through optical couplers with an isolation voltage of at least 1500 Volts. The controller should accept station battery voltage level inputs. Controller input modules should be strappable for 24, 48 or 110 Volt station batteries. Controller digital input modules should also have straps to allow any contact input to cause a hardware shutdown directly to the stop relay.
5.5.7.1.3 DC Analog Inputs
The controller should accept 0-1ma, 0-5V, 4-20ma or 1-5V DC analog signals. The controller should be able to measure DC analog signals with as much as 5 volts common mode signal with differential inputs. The controller should provide ground straps that can be inserted on the negative lead of any input signal that should be grounded at the controller. The controller should also provide selective terminating resistors for 1ma and 20ma signals. The DC analog signals should be converted to digital signals using at minimum 12 bit analog to digital converter in the controller with all conversion errors considered the controller should maintain an accuracy of 0.1% or better of full scale and a resolution of 1 part or less in 2000. All DC analog inputs should be protected from transient spikes and voltages with circuitry that meets the IEEE surge withstand test.
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5.5.7.1.4 AC current inputs
The controller should connect directly to current transformers. The controller should accurately measure all current inputs from 0-6.25 amps. It should withstand 10 amps continuously and 50 amps for 1 second. The controller should be able to measure magnitude of the current with a true RMS to DC converter and its phase shift with respect voltage. The current measuring accuracy should be to .1% and the phase shift accuracy should be to .1 degree. The controller should induce a burden of less than .5VA on each current transformer it connects to.
5.5.7.1.5 AC voltage inputs
The controller should connect directly to the potential transformers. The controller should accurately measure voltage inputs from 80 to 150 VAC. It should withstand up to 200 VAC continuously. The controller should be able to measure the magnitude of the voltage with a true RMS to DC converter and measure the phase shift of the voltage with respect to current. The voltage measuring accuracy should be to .1% and the phase shift accuracy should be to .1 degree. The controller should induce a burden of less than 1 VA in each potential transformer that it connects to.
5.5.7.1.6 Control outputs
The controller should provide control relays to operate the circuit breaker, voltage regulator, and other equipment. The contacts should be DPDT rated 125 VDC at 0.5 A. Two contacts should be available from the DPDT relay and either should be strappable as normally closed or normally open. An optional high-powered relay should be available that provides one normally open contact rate 150 VDC at 10A. Each relay should have an LED indicator mounted on a manual control panel to indicate the status of the relay, on or off. Next to the indicating LED should be a switch to operate the relay manually. Each switch/LED should be clearly marked as to its function.
5.5.7.1.7 RTD inputs
The controller should have provisions to connect directly to RTDs. RTD readings should be corrected for nonlinearly and readings should be accurate to + 0.25oC. The temperature range should be 0-160oC. The controller must have a 10, 100 and 120 ohms 8 input RTD module. The correct linearizing curve should be selected by configuring. The controller should be capable of reading temperatures from eight RTDs. If eight RTDs are not required, any of the RTD inputs should be able to be used as a 4-20 mA analog input. Each of the eight inputs should be assigned three alarm set points; two high alarm set points and one low alarm set point.
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5.5.7.1.8 Analog outputs
The controller should output 4-20ma signals for calculated signals such as KW, KVARS, power factor, frequency, voltage, and current. The signals should be isolated outputs with 1000 common mode voltage capability. The accuracy of these outputs should be better than .25%.
5.5.7.1.9 Alarm outputs (option)
The controller should be capable of outputting contacts for alarms that it generates internally. The contact rating for these alarms should be 1 Amps. at 120 VDC. All digital inputs should be capable of meeting the surge withstand capability in accordance with ANSI/IEEE C37.90.
5.5.7.1.10 Electrical transducers
The controller should connect directly to current transformers (CTs) and potential transformers (PTs). The controller should be capable of deriving the generator voltage (line to line and line to neutral), generator amps, generator WATTS, generator VARS, generator Power factor, generator kVA, generator frequency and bus frequency from the CTs and PTs: The controller should be configurable for open delta (line to line) or star (line to neutral) connected CTs and PTs.
5.5.8 Supervisory Controller
Standard Desktop Redundant Computer/Mini computer should be used as Supervisory Controller and should at minimum have following configuration: Intel Pentium IV Processor 500 MHz (or more recent) / Desktop Mini computer with support for running windows 2000.
512 KB second level cache 128 MB SDRAM 1.44 MB FDD 40 GB Ultra ATA HDD 40X CD-ROM drive AGP integrated graphic controller with 4 MB VRAM 17" Digital Colour Monitor Keyboard, Mouse
5.5.9 Speed Sensor
A speed sensor to be mounted on generator unit shaft giving output as 4 to 20 mA/0-5 V DC is to be provided.
5.5.10 Wicket gate position transducer
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It should comprise of LVDT mounted on hydraulic cylinder for actuating wicket gate.
It should convert linear movement of cylinder into 4-20 mA signal. 4 mA should
correspond to 0% and 20 mA to 100% stroke of the servomotor.
5.5.11 Upstream water level transducer
Two level sensors, one float operated and other non-floated should be provided for level controlled operation of the machine. The level controller should be redundant to each other. One level transducer may consist of a diaphragm type sensor and internal signal conditioning system and should be able to provide standard output such as 4 to 20 mA/0-5 V DC.
5.5.12 Speed switches
Speed switches should be provided for application of brake, overspeed tripping and creep at 30%, 112% and 5% of the rated speed respectively.
5.5.13 Programming & Training Console
The Console should permit software development and operator training while providing backup hardware for use where the manual operator interface is out of service. Interlocking should be provided to permit only one console to be in control at a time.
5.5.14 Printers
Printer/Hard copy units must be provided with supervisory and unit controllers.
5.5.15 Recorders
The plant control system should include video recording system of selected parameters i.e. Generator temperature etc.
5.6 Communication Link
i) Scope
Design, supply, delivery, Site, erection, communication and training of personnel for communication links between the power house and Mukerian Stage I for off-site control and communication and between power house and dasuya grid substation (interlinking points) for voice communication.
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ii) Code Standards
• ANSI/IEEE 1010 – 1987 • US Army of Engineers Engineering Manual • Relevant National / International Standards
The contractor shall furnish detailed design and calculation for approval by purchaser.
iii) Regulatory Requirement
Govt. regulatory requirement and sanctions for the communication system shall be obtained by Contractor. Necessary assistance will be provided by Purchaser.
5.6.1 Dedicated Communication by Fiber Optic System Cable
Dedicated communication system for SCADA, voice communication and code call paging system from power house to offsite control at Power House IV of stage I shall be by Fiber optic cable. Code call facility shall be provided for paging key personnel.
Fiber optic cable
A fiber-optic cable system consisting of a terminal with multiplexing equipment, and a transmitter and receiver coupled to fiber-optic light conductors that are routed to the other terminal, which also has a receiver, transmitter, and multiplexing equipment shall be provided. Because the transmission medium is nonmetallic, it offers the advantage of electrical isolation between terminals and immunity from electromagnetic interference.
The Fiber optic cable shall be laid along the canal bank and no right of way problem is anticipated.
Repeaters
Repeaters if needed shall be provided. Necessary equipment at sending and receiving and for interfacing remote supervisory controller at Power House IV with SCADA. Centralized SCADA system to remote supervisory control in the control room of Power House No. IV of stage I shall be provided by the dedicated Fiber optic couple. The
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design will be subject to approval by purchaser and will confirm to latest relevant standard.
Local area network (LAN)
Local area network if proposed inside the Power House for distributed control otherwise shall also connected by Fiber optic cable.
5.6.2 PLCC System
Two sets of PLCC system, line matching units and protective device shall also to be supplied, installed and commissioned for communication and control between Power House (emergency link) and Grid Substation for voice communication. Coupling voltage transformer and Wave trap have been covered in switchyard equipment. The equipment to be supplied should have got the facility of transmission of speech
and data simultaneously. Data transmission speed should be 9600 bps. To design the
PLCC system following line parameters are to be taken for a single circuit ---- kV
line.
a) Conductor - ACSR with a cross sectional area as ----mm2 b) Line impedances
i) L = -------- ohm/km per phase ii) Inductive Reactive = -------- ohm/km per phase
iii) A.C. Resistance = --------- ohm/km at 20o C c) Transmission Voltage ---- kV d) Range of transmission ---- km e) Distance between switchyard ---- meters and control room f) Input voltage to the system 48 V DC Above parameters are to be worked-out taking configuration of --- kV line as right angled with Base = ---- m and perpendicular as ---- m. These parameters may please also be verified at Tenderers end also. PLCC is to be interfaced with supervisory controller with serial/parallel interfaces. Interconnection of outdoor equipment with PLCC should be done via shielded coaxial cable.
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5.7 Factory Tests for Unit Control Switchboards
12. Review front and rear elevations versus the final approved drawings. Check each item of equipment for proper location and verify the instrument/catalog number is correct per the specification.
13. Review the interior of the UCS in the same manner as the elevations. In addition, verify the lighting is adequate and grounding connections are provided.
14. Check anchor channels and cable entrances. Confirm they are in accordance with the drawings.
15. Review test certificate or witness the insulation resistance test of all wiring, current transformers, and potential transformers.
16. Check approximately 5 to 10 percent of the internal cabling. Verify that the following items conform to the drawings :
• Cable numbers; • Terminal block designations; • Terminal designations on individual components such as control switches
and lockout relay; • Raceway layouts; and • Equipment identification nameplates.
17. Activate all protective relays. Confirm that the appropriate lockout relay is
energized and the correct annunciation and/or printout occurs. 18. Confirm that settings of all protective relays are in accordance with approved
documents. 19. Check all annunciation points. 20. Check factory calibration of all devices possible, including electronic speed
relays, current and potential transformers, and vibration monitors. 21. PLC checks:
• Check the I/O racks for type and number of analog and digital I/O cards; • Check for future expansion capabilities on the I/O racks; • Check for surge protection provided on the I/O rack and I/O cards; • Identify grounding connections for the PLC and the I/O rack; determine
whether chassis and logic grounds are the same or separate (this will affect the type and quantity of external surge protection required);
• Review the PLC ladder diagram viewed on the video display terminal versus the final approved PLC software coding documentation; and
• Verify that modem connections are provided and functional.
22. Perform the function checks listed below with the final approved schematics, PLC software coding, and control block logic diagrams in front of you. All premissives and interlocks should be provided by using the “dummy” toggle switchboard to provide these inputs.
• Manual start/stop sequence (does not apply to redundant PLC control
schemes); • Auto start/stop sequence;
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• Manual emergency stop sequence; • Automatic emergency stop sequence (usually performed by activating one
of the lockout relays while in the “normal running” mode ); • Change position of all control switches as follows (typically done while in
the normal running mode);
- Local control to remote control - Remote control to local control - Manual control to automatic control - Headwater level control “OFF” to “ON” - Headwater level control “ON” to “OFF” - Excitation manual control to excitation automatic control - Excitation automatic control to excitation manual control; and • Verify the performance of the automatic synchronizing circuit and the
manual sync-check relay (if provided). 5.8 Field Tests for Unit Control Switchboards
1. Verify tags on all factory-calibrated instrumentation devices. 10. Check all external interconnection wiring against the approved power
house/equipment drawings, verifying the following items : • Cable numbers and type; • Terminal block designations; and • Raceway layouts
11. Perform point-to-point continuity and megger tests on all external cabling. 12. Calibrate all remaining instrumentation devices. 13. “Bench test” all protective relays to ensure proper settings. 14. Perform functional checks tests on all unit and station auxiliary equipment
controlled from the UCS to verify proper operation. 15. Perform functional checks on unit start/stop sequences, duplicating the factory
sequences. These checks should be performed first with the associated power circuits de-energized, and then with both power and control circuits energized.
16. Methodically document steps 1 through 7 to ensure that no cables, instrumentation devices, protective relays, or control systems have been overlooked.
17. Water-up the unit and perform all start/stop sequences. 5.9 Additional Factory and Field Tests for Distributed Control Systems
7. Point-by-point database check. 8. Database linkage to graphical displays. 9. Response times during normal loading and high activity loading scenarios for:
• Graphical display updates; • Control sequence implementation; • Alarm processing and logging; and • Sequence of events recording
10. Communications connectivity/protocols. 11. Man-machine interface (MMI) user capabilities. 12. Application software functionality.
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5.10 Data/ Document to be furnished by the Bidder
Bidder shall furnish the following data/documents with the Bid
♦ All technical parameters such as baud rate, frequency, memory capacity input/output capacity of modules expansion capacity of the SCADA system, etc.
♦ Input/ Output list. ♦ List of parameters to be monitored from CRT/key board and the details of the
same. ♦ Redundancy provided for any of the equipment. ♦ List of application software. ♦ Bill of material ♦ Price schedule as per the enclosed schedule. ♦ Type of Cables ♦ List of essential spares ♦ Experience list. ♦ Manual/ catalogues of each equipment supplied by him. ♦ Plant operation philosophy.
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