1.1 grid operation and control_iit
TRANSCRIPT
GETCO, VadodaraGujarat
GRID OPERATIONAND
MONITORING
Topics covered
� Power System Operation
� Statutory frame work
� Grid Operation Technology - Today
� Grid Operation Technology - Tomorrow
� Defense mechanism for secure and reliable power
system operation - SPS
� Opportunity for research
2
At Present Indian Power SectorFive Region.
– Western Region– Eastern Region– Northern Region– Southern Region– Northern Eastern Region
One Grid:Recently on 31.12.13 , NEW grid hasbeen connected with SR grid through765 KV S/C Solapur – Raichur ACcircuit. Hence, all regions are nowinterconnected and it becomes onegrid.Same frequency at Chennai, Delhi,Ahmedabad, Mumbai, Kolkatta.
Western Region
The western regional grid comprises of the following five states & U/T1. Gujarat 6. U.T. of Diu & Daman2. Maharastra 7. U.T. of Dadra & Nagar Haveli3. Madhya Pradesh4. Chhattisgarh5. Goa
The Western Regional LDC is at Mumbai4
Power System Operation in India
WRLDC SRLDCNRLDCERLDCNERLDC
ISGS / UMPP CTU (ISTS) SLDC Private ISTS Bulk consumerconnected to ISTS
STUState generating StationsState / Private / Renewables
DiscomsState / Private
ISTS
STU
Role and ResponsibilityISO (Independent System Operator)
6
� Grid monitoring and control
� Merit order despatch
� Adhering to system parameters
Voltage – Reactive power management
Frequency – Load – Generation balance, Maintaining Deviation
within limit.
� Energy accounting & settlement
� Declare Capability in energy by the generator for recovery of fix
charge by the generator and Despatch Schedule in energy for the
generator for recovery of fuel charges.
� Unscheduled Interchange settlement (Linked to real time frequency)
� Reactive energy Charges account.
Role and ResponsibilityISO (Independent System Operator)
7
�Analysis of real time / historical data on biannual / annual basis to identify
weak elements in grid and interface with STU for network improvement.
�Assessment of transfer capability in order to facilitate market operation
�Open Access - SLDC is a nodal agency for granting Short Term Open
Access.
�Annual generating unit outage schedule finalization
�Day ahead and in real time EHV line / Equipment outage finalization
�Development and up gradation of SLDC
�Adoption of State of art grid control technology
�RTUs and SCADA Equipment maintenance.
Statutory framework for managing grid operation1. Indian Electricity Grid Code – 2010:
(Hon’ble CERC order No. L-1/18/2010-CERC New Delhi, 28th April 2010)A single set of technical and commercial rules, encompassing all theUtilities connected to/or using the inter-State transmission system(ISTS)�Role of various organizations and linkages:
� Role of NLDC, RLDC, CTU, RPC, CEA SLDC & STU.�Planning code for Inter State Transmission System (ISTS)�Connection code – Basic rules for connectivity with ISTS
�Operating Code:
Provision of RGMO:� For the all thermal generating units of 200 MW and above� All hydro units of 10 MW and above� All governors shall have a droop setting of between 3% and 6%.� Ripple filter shall be +/- 0.03 Hz in order to ignored for load correction
and to prevent governor hunting.8
Statutory framework for managing grid operation
1. Indian Electricity Grid Code – 2010: Contd..
Frequency band (revised in 2nd amendment):
49.90 Hz to 50.05 Hz – w.e.f. 17.02.14.
Voltage Limit :
Special requirement for wind / Solar generators:
System operator shall make all efforts to evacuate the available solar and
wind power and treat as a must-run station. However, System operator
may instruct the solar /wind generator to back down generation on
consideration of grid security or safety of any equipment or personnel is
endangered.9
Statutory framework for managing grid operation1. Indian Electricity Grid Code – 2010: Contd..
Demand estimation for operational planning:
On daily/weekly/monthly/yearly basis for load - generation balance planning
Demand Disconnection:The SLDC through respective State Electricity Boards/Distribution Licenseesshall also formulate and implement state-of-the-art demand managementschemes for automatic demand management like rotational load shedding,demand response.
Outage Planning:�To minimise surplus or deficits, if any, in the system requirement of power andenergy and help operate system within Security Standards.�To optimize the transmission outages of the elements.Recovery procedure:.�Detailed plans and procedures for restoration of the regional grid underpartial/total blackout shall be developed by RLDC and shall be reviewed /updated annually.�Mock trial runs of the procedure for different subsystems shall be carried out atleast once every six months under intimation to the RLDC.
Statutory framework for managing grid operation1. Indian Electricity Grid Code – 2010: Contd..
Scheduling and Despatch Code:Procedure for scheduling and despatch from ISGS.
Statutory framework for managing grid operation
1. Indian Electricity Grid Code – 2010: Contd..
Scheduling of wind and solar energy sources:� With effect from 1.1.2011 Scheduling of wind power generation plants
would have to be done where the sum of generation capacity of suchplants is 10 MW and above and connection point is 33 KV and above,and where PPA has not yet been signed.
� There may be maximum of 8 revisions for each 3 hour time slot startingfrom 00:00 hours during the day.
Statutory frameworkFrequency management linked to penalty
2. Deviation Settlement Regulation – 2014(Hon’ble CERC order No. L-1/132/2013/CERC New Delhi 06th January 2014)
Objective:
�To maintain grid discipline and grid security through the commercial
mechanism
�To drive distribution utilities to go for planned procurement of
electricity not to rely upon over-drawl from the grid for meeting their
consumer demands.
�To enforce strict volume limits on over drawl / under drawl and over-
injection/under-injection irrespective of the grid frequency.
13
14
49.70 49.75 49.80 49.85 49.90 49.95 50.00 50.05 50.10
8.24 6.99 5.94 4.90 3.86 2.82 1.78 0.00 0.00
Under drawl / overinjection
Penalty @ 1.78 perKWh
No over drawl isallowed.
Overdrawl@ 16.48 Rs / KWh
i.e. 100% additionalcharge of Freq 49.70
Hz
Frequency range
Rate in Rs per KWh
Under drawls by the buyer / Over injcetion by seller in a time block in excess of 12%of schedule or 150 MW, shall be zero”.
If 12% of drawl schedule is more than 150 MW, thenadditional charges is as below:�OD in range (150 to 200 MW) 20% additional charges.�OD in range (200 to 250 MW) 40% additional charges.�OD more than 250 MW , 100 % additional charge
If 12% of drawl schedule is less than 150 MW, thenadditional charges is as below:�OD in range (12% to 15%) 20% additional charges.�OD in range (15% to 20%) 40% additional charges.�OD more than 20%, 100 % additional charge
Sustain deviation from schedule in one direction (+/-) of entity, entity shallhave to make sign change at least once after every 12 time block.
Statutory framework – Tariff mechanism for ISTS(Point of connection charges regulation 2010)
3. Sharing of Inter State Transmission Charges and Losses regulation:(Hon’ble CERC order No. L-1/44/2010-CERC Dated: 15th June 2010)
Principles for sharing ISTS charges and losses.� Based on the Yearly Transmission Charges of ISTS Transmission Licensees and
transmission losses in the ISTS network, the Implementing Agency shall compute thePoint of Connection charges and Loss Allocation Factors for all Designated ISTScustomer
(a) Using load-flow based methods; and(b) based on the Point of Connection Charging method.
This methodology sensitive to distance, direction and usage of network.Charges for LTA/MTOA : Rs/MW/MonthCharges for STOA : Rs/MW/Hour
Role of Implementing Agency: (NLDC)� Collection the Basic Network data pertaining to the network elements.� The generation and load at the various network nodes� Responsibility to run AC load flows using the basic Network, nodal generation and
nodal demand to ensure Load Generation balance is entrusted to IA.
The CTU shall be responsible for raising the transmission bills, collection anddisbursement of transmission charges to ISTS transmission licensees.
Statutory framework – Open Access – Short Term4. Open Access in inter-State Transmission) Regulations:
(Hon’ble CERC order No.L-7/105(121)/2007-CERC Dated 25th January, 2008)� “Short-term open access” means open access for a period up to one (1)
month at one time.� “Bilateral transaction” means a transaction for exchange of energy (MWh)
between a specified buyer and a specified seller, directly or through a tradinglicensee or discovered at power exchange through anonymous bidding, from aspecified point of injection to a specified point of drawl for a fixed or varyingquantum of power (MW) for any time period during a month.
� “collective transaction” means a set of transactions discovered in powerexchange through anonymous, simultaneous competitive bidding by buyersand sellers;
Eligibility for allowing STOA:The surplus capacity available on the ISTS after use by the long-term
customer and the medium-term customer, by virtue of-(a) Inherent design margins;(b)Margins available due to variation in power flows;(c)Margins available due to in-built spare transmission capacity
created to cater to future load growth or generation addition.
Statutory framework – Open Access – Short Term4. Open Access in inter-State Transmission) Regulations:
Nodal Agencies:�NLDC: For collective transections�RLDC: For bilateral transections of the region where point of drawal ofelectricity is situated.�SLDC: For intra state bilateral transections.
� Wherever the proposed bilateral transaction has a State utility or an intra-State entity as a buyer or a seller, concurrence of the SLDC is required.
� When a State utility or an intra-State entity proposes to participate intrading through a power exchange, it shall obtain a “no objection” or aprior standing clearance from the SLDC.
Statutory framework5. Renewable Regulatory Fund (RRF) regulation:
(Hon’ble CERC order No. L-1/18/2010-CERC Date of Order: 18-2-2011)
Applicable to:1.Wind farms with collective capacity of 10 MW and above connected at 33 KV leveland above.2.The Solar generating plants with capacity of 5 MW and above connected at 33 KVlevel and above.
The RRF shall be maintained and operated by the NLDC
�The wind generators shall be responsible for forecasting their generation uptoan accuracy of 70%. For actual generation within +/- 30% of the schedule, no UIwould be payable/receivable.�A maximum generation of 150% of the schedule only, would be allowed in atime block, for injection by wind, from the grid security point of view.�The schedule of solar generation shall be given by the generator based onavailability of the generator, weather forecasting, solar insolation, season andnormal solar generation curve and shall be vetted by the RLDC. If RLDC is of theopinion that the schedule is not realistic, it may ask the solar generator to modifythe schedule.
�No UI charges payable/receivable by Solar Generator 18
Statutory framework6. Congestion Management:
(Hon’ble CERC order No.L-7/139(159)/2008 Date of order: 22.4.2013)
Corridor shall be considered congested if:� Grid voltage in the important nodes downstream/ upstream of the
corridor is beyond the operating range specified in the IEGC and/or� The real time power flow along a corridor is such that n-1 criteria may
not be satisfied.� One or more transmission lines in the corridor are loaded beyond the
normal limit specified in CEA Manual on Transmission PlanningCriteria.
Congestion charge would be levied for
a) Over drawal or under-injection in the importing control area and
b) Under drawal or over-injection in the exporting control area.
It is also become applicable for an intra-regional corridor of one region.
TYPICAL SCADA SYSTEM
SCADAH/W &
S/WMEDIA
C TXO RXM EM QN P
T
C TXO RxM EM QN P
T
R
T
U
T PR AA NN ES LDUCER
C & R
PANEL
CONTROLCENTRE SUBSTATION / GEN STATION
COMMNMEDIA
FIELD UNIT
Grid Operation Technology - Today
Load Despatching Facilities in India
SLDC GJ M
SRLDC
NLDC Main
NRLDC
Sub LDCJambuva
Sub LDCJetpur
→ PG FO Comn→ VSAT Comm
Sub LDCGandhinagar
NLDC Backup
WRLDC M ERLDC NERLDC
SLDC GJ B
10 Sec
2 Sec
2 Sec
20 Sec
New DelhiKatwariasarai
KalcuttaGolf Course Road
2014 October
RTU C RTU X
WRLDC B
2008 August
Tools for managingsystem operation:EMS package ofSCADA:�PNA�NSP�DDC�SDF
SLDC Control Centre
22
HMI (Work Station)
Application server
LAN
23
SOFTWARE REPRESENTATION OF REAL TIME HADWAREPOSITION at SLDC
10/100 MBPS HUB
10/100 MBPS HUB
ROUTER(2)
MUX(2)
OFC WIDEBANDCOMMUNICATION
OFC WIDEBANDCOMMUNICATION
RLDC
Sub-LDC
24
SCADA at Sub-LDC
SOFTWARE REPRESENTATION OF REAL TIMEHARDWARE POSITION WITH SCADA SYSTEM at Sub-LDC
26
Remote Terminal Unit at Field Level
Grid Operation – Todaywith Present SCADA
� MW, MVAR,Voltage, Frequency parameter reporting to control
center.
� No Time stamped data.
� State Estimator for load flow study.
� It is solution of Non-Linear equation.
� Best estimation of state of system known to operator.
� Limitation particularly with large complex system.
� Good for visualization but limited Decision making tools.
� slow data reporting time
� Steady state operation.
Internal Fire-wall
External Fire-wall
Work-station DTS Server
GPSVPS Work-station SCADA/EMS server
ICCP server F/wRouter
PrinterISRServer
NMSServer
Web-server
F/w RouterRouterRemote-VDU
Data ReplicaServer CMC
DDSServerF/w Router
Work-station
Internet
External DMZ
Internal DMZ
ICCPLAN
SCADALAN
Data LAN
OFFLINELAN
DTSLAN
RLDC/BackupSLDC/Sub-LDC
Corporate Network
CMC : Centralized Monitoring ConsoleISR : Information Storage and RetrievalNMS : Network Management ServerDDS: Database Development ServerDMZ: Demelitarized Zone
Grid Operation Technology - Tomorrow
Internal Fire-wall
External Fire-wall
GPS
VPS Work-stationSCADA/EMSserver
ICCP server F/wRouter
PrinterISRServer
NMSServer
Web-server
F/w RouterRouterRemote-VDU
Data ReplicaServer CMC
DDSServerF/w Router
Work-station
Internet
ExternalDMZ
Internal DMZ
ICCP LAN
SCADA LAN
Data LAN
OFFLINE LAN
RLDC/SLDC/Sub-LDC
Corporate Network
RTU IEC 60870-5-101 RTU IEC 60870-5-104
Data acquisitionLAN
Network Architecture for GETCO Backup Control Center Sub-LDC
30
Additional Features in New SCADA
Existing SCADA UpcomingSCADA
Remarks
Display 4 30
Trend Trend With 4points
New Featurewith 16 points
EMS Package Concurrent Access 1 4
Outage Scheduler Not Available New Feature
Transient Stability Not Available New Feature
Transmission /Corridor CapabilityMonitoring
Not Available New Feature
Web-interface Not Available New Feature
Event Based Email-SMS Not Available New Feature
31
Conti…..Features
Existing Upcoming Remarks
LANCopper PairCAT-6
Fiber No limitation ofBandwidth
Back up control center Not Available Available
Redundancy in Crossconnectivity betweenALDCs
Not Available Available Through BackUpSLDC
VPS system Bulb illuminated LED based 1)LessConsumption andlonger life2)Portableinterface
Firewall Not available Available
Intrusion Detection andPrevention System
Not Available Available Added Security
Video Conferencingfacility
Not Available New Features At SLDC &Backup SLDC.
32
BENEFIT TO THE SYSTEM OPERATOR:1)More User Friendly and Better GUI (3d trending)
2)More Number of Points for a Single Trend
3)More Number of Concurrent Displays
4) WEB Enabled interface - Visibility access from any where
5) Event Based SMS facility
SYSTEM BENEFIT:
1)Integration with WAMS/PMU
2)Integration with Renewable Energy Control Center
3) Fire wall provides better cyber security
New SCADA Highlights
Need for New System
� Time stamped data required for complex system.
� System stress depend upon Angular difference of
adjacent buses.
� Fast reporting of data require.
� Real time Angular measurement.
� Dynamic performance of system required.
� Decision making tools for system operator.
� Dynamic operation.
Solution is PMU & WAMS for grid operation
Grid Operation Technology
34
Today Tomorrow
Grid Operation technology – TomorrowPhasor Measurement Unit (PMU)
� PMU gives Phasor, voltage & current with its angular position.
� It is useful for system stress.
� Fast reporting rate 10,25,50 samples per cycle.
� It also gives frequency and rate of change of frequency.
� It is useful for Generation stability.
� PMU takes current and bus PT as input where it has placed.
� PMU send data precisely and time synchronized.
� It offers dynamic visibility of system behavior.
� Direct Angle measurement gives solution of linear equation.
� Intelligent decision making tools can be made for dynamic system
operation work.
Significance of Angle Difference on Power flow
PMU & WAMS
37
PMU Architecture
Sinusoidal representation of AC circuit
Two characteristics Magnitude and Angle
AC circuits Wave form and Phasorrepresentation
Phasor representation
In AC circuit, power flows from larger phaseAngle to smaller phase Angle.
Wide Area Monitoring System (WAMS)
� WAMS designed with PMU placed at different locations.
� All PMU data reporting to control center with time
synchronized.
� It gives information of phasor of different location at a time.
� Fast, time synchronized data enable a better indication of
grid stress.
� It can be used to trigger corrective actions to maintain
reliability.
� Improve situational awareness for the operator of the large
complex power system through the use of effective
visualization tools.
Wide Area Monitoring System (WAMS)GETCO Plan
� GETCO designed WAMS for system operation with a vision to have full
fledged WAMS in near future in phased manner.
� 25 Nos. location for PMU placement in first phase.
� Advanced MPLS-Communication between PMU to control center, SLDC.
� PMU will be given all current and Bus voltage as input where it has
placed.
� Multiple PMU used at many stations.
� PMU location decided on strategic technical importance.
� In direct observability characteristics will be used for more penetration
level.
� In future with more PMU placement full fledged WAMS for Gujarat system
operation work.
PMU1.....n
switch Router switchRouter
PMU1.....n
m
m
Existing LANColourprinter
Workstationconsole-1
Workstationconsole-2
Proposed Architecture of WAMS:
PDC-1 PDC-2
DataHistorianserver-1
DataHistorianserver-2
Router cum firewall
Router cum firewall
MPLS-Communication
Other LDC
Wide Area Monitoring System (WAMS)GETCO plan
� WAMS will improve situational awareness of operator with better real timevisualization..
� Voltage, current with its Angular position enable to know system stress inreal time.
� frequency and rate of change of frequency enable to know effect ofswitching action.
� Angular difference between two station and Grid as a whole enableoperator to know system capability in real time with changing scenario.
� It is planned to develop following Intelligent Analytics tool from PMU datafor system operation.
� On line oscillation stability mode identification.� Hybrid state estimator� Dynamic security Analysis (DSA) with voltage stability.
Development of Analytics
Following are some Analytics that can be developed from
PMU data
� Hybrid (Linear) state estimator.
�On line oscillation stability.
�Dynamic Security Assessment.
�Voltage Stability Analysis.
�Frequency Stability Analysis.
�Vulnerability Analysis of relay for Zone-3 blocking.
�Calibration of CVT/CT
�Transient stability Analysis.
Analytics software for system operation
On line oscillation stability mode identification.
� software will find oscillation mode
� Inter- area oscillation will be observed.
�Better damping means system is strong and capable for
contingency if any arise in future.
�Important for planning to find weak area.
�Effect of switching action and damping equipment can be
ascertain.
�Index for system strength well in advance for operator.
�One more parameter for outage management.
Visualization of Oscillation mode
47
Yellow Light Implying Dampingbelow Alert Levels (i.e. 5%)
Red Light Implying Dampingbelow Alarm Levels (i.e. 3%)
Dial Chart for Damping factor
Analytics software for system operation
Hybrid state Estimator�State estimator use PMU data and remaining data from SCADA
measurement
�Improve state estimation as PMU gives actual Angle measurement
precisely
�It will work as state measurement of system, solution of linear equation
when sufficient PMU data available.
�Useful to find safe loading of each equipment dynamically with
changing system scenario.
�optimization of resources with confident.
�Useful for planning of Transmission infrastructure based on system
behavior in real time different scenario.
GUI for Voltage Visualization
49
Analytics software for system operation
Dynamic Security Assessment with voltage stability.�Perform security assessment of system on predefined time interval.
�suggest possible remedial measures to operators.
�Path towards on line Transient stability
�It will show voltage limit of area, zone as defined.
�Intelligent tool for operator to know system behavior dynamically and
remedial action against possible contingency.
� It will make operator more intelligent to maintain system in secure
status and alarm in advance for possible contingency.
Integration with SCADA
Integration with SCADA
� Existing EMS data can be used for PMU applications.
� Full observability of Grid from PMU data can be achieved
in phased manner.
� Short term Analytics uses EMS data.
� Model validation and Hybrid state estimator are example
of SCADA Integration.
� Hybrid state Estimator uses PMU data and SCADA EMS
data giving more accuracy then conventional.
1. To ensure load – Generation balance in order to maintain systemfrequency within permissible band i.e. (49.90 Hz to 50.10 Hz):
a. Long term Planning:
� Annual planning of State & Private Sector Unit outages is being done to
ensure adequate availability to meet peak demand of every month.
� To keeping 10 to 15% margin for forced outages.
� Seasonal variation of renewables is taken into account.
� Seasonal effects is considered
� Outages of evacuation lines along with planned shutdown of units.
Grid Operation
53
b. Short term Planning:
� Planned shutdown of Units is reviewed.
� If any need arises, all generators are informed to squeeze their unit
outages.
� Finalize Monthly line / EHV elements outage schedule to ensure maximum
availability during peak hours.
c. Day a head planning:
� Generation availability from all the generators for next day.
� SLDC receives data of load forecast from Discoms.
� Unit outage request up to 16:00 Hrs for next day are being taken in to
account.
Considering all above, system operations are being planned.
54
2. To operate power system such a way that it should remain inStable State :Stable state means :
� System variables are in the normal range.� No equipment is being overloaded.� System is able to withstand a contingency without violating any of
the constraints.Actions are being planed to operate system in Stable State:
� Rescheduling of generation� Deferment of elements outages� Switching operations of reactors and capacitor bank in order to control
voltages at important node.� Close monitoring of weather parameters.� Formulation & Review of defense mechanism
SPS at strategic locations.Review of load connected under Df/Dt & UFR relays.Formulation of islanding scheme.
Grid Operation
55
Initiatives for better Power System Operation
� Keen interest to facilitate outages for construction of new EHV lines and
for R & M work of EHV lines.
� Proactive actions to facilitate outages of important elements
� SLDC has initiated RE desk to accommodate real time weather data of
the State and forecast from the various reliable sources / tools and
prepare anticipated variation for wind / Solar generation as well as load.
� Black start mock drill at regular interval:
� SOCC meetings at regular interval
� keen interest to relieve congestion in the network by proposing
worthwhile changes in network topology and getting them implemented
through the concerned agencies.56
Initiatives for better Power System Operation� Data visualization at all control centres & also accessing reliable data of
renewable energy generation in real time
� Adoption of prevailing latest technology in Monitoring system (WAMS /
SCADA), IT (Software development) and in Communication (AMR solution /
Data acquisition using radio link, GSM etc.
� Continuous improvement of web-site.
57
Defense Mechanisms
Any type of Grid Disturbance (Major or Minor) isdetrimental for Power System and badly affects theSociety and Economy.
•Properly planned defense mechanisms helps in
� Prevention of any type of grid disturbance.
� Minimizing the damages due to grid disturbances
� Faster Restoration of System.
•Based on the Root Cause Analysis of Past Grid Incidents / Disturbances,
Preventive, Corrective and Restorative Action Plans have been developed
to handle any contingency
58
Defense MechanismsPreventive Action Plans:
�Development of Ring Main System for MetroCities
�Islanding Schemes
�System Protection Schemes (RAS)�Conventional Protection Schemes
�Offline System Studies
�Reactive Power Management
�Special Switching Arrangements
�Power System Visualization
�Phase Angle Monitoring (PMU)
�Workshops & Seminar
�Training on Simulator
�Mock Trial of Generators / Transmission
System
�Information Management System
Corrective Action Plans:
�Weather Monitoring
�Revision in Protection Setting like
blocking of line tripping on Over current
etc.
Special Protection Scheme
• It is designed to detect predetermined system conditions and
automatically take corrective actions, other than the isolation of faulted
components, to meet system performance requirements or to limit the
impact of: two or more elements removed, an extreme event, or
Cascading.
• Such schemes are designed to maintain:
� System Stability
� Acceptable System Voltages,
� Acceptable Power flows, or to address other reliability concerns.
Hence, SPS provides the required stabilizing force necessary topreserve the system stability
The general characteristics of SPS are:
� Normally sleeping systems, Operate infrequently
� Control actions taken is predetermined
� Can be armed or disarmed depending upon system conditions
� Can comprise a large number of coordinated actions, in a cascaded
manner
All Special Protection Schemes consists of three main parts:
1.Input:
Level of physical magnitudes / Status of circuits breakers
2.Decision making system : To initiate some actions based on inputs
3. Output
Generator tripping, Fast valve opening, Runback Scheme or load
shedding.
Special Protection Scheme in Gujarat Power System1. SPS at APL complex to restrict power flow within limits in AC network:(Earlier)
Stage-1
Stage-2
Stage-3
Setting(Current/MW)
Time DelaySetting
(Current/MW)Time Delay
Stage-1 715 A 10 sec 715 A 10 sec
Stage-2 650 MW 1.5 sec 750 MW 1.5 sec
Stage-3 750 MW 4 sec 800 MW 4 sec
Action
Tripping of Unit-3 or Unit-4 to reducegeneration by 330 MW
Tripping of any one unit among Unit-5 to Unit-9 to reduce generation by 660 MW
Alarm
600 MW 1.5 sec Back down of generation from Unit-7-8-9
700 MW 4 sec
715 A 10 sec Alarm
Phase-2 Special Protection Scheme Settings
Setting (Current/MW) Time Delay Action400kV Mundra-Versana & Mundra-Hadala Circuit
Tripping of Unit-3 or Unit-4 as per selection
400kV Mundra-Sami Circuit-1&2
Group 1 (Both Line in service
without FSC)
Group 2 (Single Line in service
without FSC)
Group 3 (Both Line in servicewith FSC)
Group 4 (Single Line in servicewith FSC)
APL-DEHGAM BOTH LINE LOAD FLOW MORE THAN 700 MW THENGENERATION
APL GENERATION 1900CGPL GENERATION 2800EPGL GENERATION 1000
727 MW FLOW ONE LINE TRIP3OOMW GEN
LOSS500 MW GEN
LOSSAPL DEHGAM 727 964 873 717APL-HADALA 321 464 400 300HADALA-CHORNIA 570 700 640 550
APL-DEHGAM BOTH LINE LOAD FLOW LESS THAN 700MW THENGENERATION
APL GENERATION 1900CGPL GENERATION 2800EPGL GENERATION 500
LESS THAN 700MW ONE LINE TRIP
3OO MW GENLOSS
500 MW GENLOSS
APL DEHGAM 640 851 758 601APL-HADALA 368 494 430 332HADALA-CHORNIA 414 530 473 380
As on today,
Stage-1
Stage-2
Stage-3
Setting(Current/MW)
Time DelaySetting
(Current/MW)Time Delay
Stage-1 715 A 10 sec 715 A 10 sec
Stage-2 850 MW 1.5 secGreater than 1000
MW1.5 sec
Stage-3Greater than
700 MW & lessthan 800
1.5 secGreater than 850MW & less than
1000 MW1.5 sec
Stage-4Greater than
650 MWwithin 15 sec.
Greater than 750MW
within 15 sec afterStage -2 or Stage-3
operation
Tripping of any one unit formAPL No. 3 or 4.
200 to 300 MW generationreduction
400kV Mundra-Versana & Mundra-Hadala CircuitSetting (Current/MW) Time Delay Action
715 A
400kV Mundra-Sami Circuit-1&2 and Sami -Dehgam line 1 & 2
10 sec Alarm
Action
4.0 SecGeneration backing down @200 MW from Unit No. 3, 4, 5or 6.
4.0 Sec
Tripping of Unit-3 or Unit-4 asper selection ( If unit No. 3 isselected for 400 KV Mundra-Sami-Dehgam route then UnitNo. 4 is selected for thissetting)
Alarm
> 600 MW with availability ofany one or both 400 KV APL-
Sami-Dehgam line.
Group 3 (Both Line in service with FSC)
Group 4 (Single Line in service with FSC)
Group 1 (Both Line in service
without FSC)
Group 2 (Single Line in service
without FSC)
Tripping of any one unit formAPL No. 5 or 6.
> 600 MW + Non availability ofboth APL - Sami or Sami -
Dehgam line
SPS at CGPL, Mundra
SPS at regional Level
To arrest rise in frequency:Automatic tripping of following units at high frequency (51.5 Hz) with time
delay of 30 Sec in case of islanding of WR from rest of NEW grid:
1. KSTPS-7 (500 MW)
2. VSTPS-7 (500 MW)
3. CGPL-10 (830 MW).
SPS for Gwalior – Agra interregional link:•An SPS was envisaged for ensuring backing down WR generation by 500
MW (VSTPS - 200 MW, KSTPS – 120 MW, CGPL - 180 MW) in case of
sudden reduction of NR import from WR on Bina-Gwalior-Agra link by 1500
MW.
67
Limitation and Challenges• Manual Control over generation, load, Switching elements
• Management of RE variations.
• RGMO / FGMO – Poor response by the generator today.
• Generation and Load balancing - To manage limit of ± 150
MW at State periphery.
• Load diversity and Load forecasting
• Assessment of transfer capability of flow gate in real time.
• Dynamic reactive power compensation. – No contribution by
the generator (VAR absorption) – managed by opening of
EHV lines.
1. Demand variation (Un expected & Expected):Grid Operation Challenges
68
2. RE generation variation:
Grid Operation Challenges
69
Operational Complexity
No of days when variationbetween Maximum and
Minimum demand
No of days when variationbetween Maximum and
Minimum wind generation
Year >2000 MW >1500 MW >1000 MW2011-12 51 159 112012-13 104 259 602013-14 114 260 82
� Variation of 1000-1200 MW generation in a day from renewable sources& 2000 MW variation in demand in a day is quite common. Such variationin the system is persistent and is handled by continuously analysingweather related information, generation regulation, optimizing theoperation of lines, ICTs and shunt elements like capacitors and reactors.
� SLDC is managing such complexities by using advanced Power SystemTools, effective planning for outages of transmission elements andgenerating units, ensuring real time data for entire grid observation etc.
Opportunity for Research� Analytics for WAMS.
� Renewable energy forecasting.
� Load forecasting methodology.
� Load balancing and grid parameters
� VSC (Voltage Source Converter)
� PST (Phase Shifting Transformer)
� STATCOM locations
� ICT tap optimization.
� Effect of harmonics in power system
� Reactive Capability testing of generators
� PSS tuning in order to damp out low frequency oscillation.
� Optimization of governor droop setting, testing of governor.
� Islanding Schemes & Special Protection Scheme designing. 71
Thank you