reactive power document and voltage control of …nerldc.in/docs/webupload/ner reactive power...

Reactive poweR document and

voltage contRol of noRth easteRn Region

December-2016

Edition-8

North Eastern Regional Load Despatch Centre Shillong

Power System operation Corporation Limited (A wholly own Subsidiary of Power Grid)

REACTIVE POWER MANAGEMENT AND VOLTAGE CONTROL IN NORTH EASTERN REGION

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CONTENTS CONTENTS .......................................................................................................................................................................1 List Details. ........................................................................................................................................................................2 List of Figures: ...................................................................................................................................................................3 List of Tables: ....................................................................................................................................................................4 Capability Curve of Generator in NER: ..............................................................................................................................4 1 REACTIVE POWER MANAGEMENT AND VOLTAGE CONTROL .....................................................................7

1.1 Introduction ................................................................................................................................. 7 1.2 Analogy of Reactive Power ................................................................................................... 9 1.3 Understanding Vectorally .................................................................................................... 11 1.4 Voltage Stability .................................................................................................................. 12 1.5 Voltage Collapse .................................................................................................................. 13 1.6 Proximity to Instability ....................................................................................................... 15 1.7 Reactive Reserve Margin .................................................................................................... 16 1.8 NER GRID – Overview ............................................................................................................. 19 1.9 Reliability Improvement Due to Local Voltage Regulation ............................................. 24

2 TRANSMISSION LINES AND REACTIVE POWER COMPENSATION ................................................................. 25 2.1 Introduction ............................................................................................................................ 25 2.2 Surge Impedance Loading (SIL) ........................................................................................... 26 2.3 Shunt Compensation in Line ............................................................................................. 26 2.4 Line loading as function of Line Length and Compensation ............................................ 27

3 SERIES AND SHUNT CAPACITOR VOLTAGE CONTROL ...................................................................................... 49 3.1 Introduction ...................................................................................................................... 49 3.2 MeSeb Capacity Building And Training Document Suggest (Sub Title As Given In The PFC Document For Corporatization Of MeSeb): .................................................................................. 50 3.3 As Per The Assam Gazette, Extraordinary, February 10, 2005 ........................................ 50

4 TRANSFORMER LOAD TAP CHANGER AND VOLTAGE CONTROL ...................................................................... 53 4.1 Introduction .............................................................................................................................. 53 4.2 As Per The Assam Gazette, Extraordinary, February 10, 2005 .............................................. 54

5 HVDC AND VOLTAGE CONTROL ........................................................................................................................... 68 5.1 Introduction ......................................................................................................................... 68 5.2 HVDC Configuration ........................................................................................................... 68 5.3 Reactive Power Source ....................................................................................................... 71 5.4 ±800 kV HVDC Bi-Pole ........................................................................................................ 71 5.5 Technical details of Biswanath Chariali –Alipurduar-Agra HVDC: ........................................ 72 5.6 Impact of Largest Filter Switching Under Different HVDC Power Order. ............................ 74

6 FACTS AND VOLTAGE CONTROL ..................................................................................................................... 75 6.1 Introduction ....................................................................................................................... 75


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6.2 Static Var Compensator (SVC) ................................................................................................ 75 6.3 Converter-based Compensator ............................................................................................. 76 6.4 Series-connected controllers ................................................................................................ 77

7 GENERATOR REACTIVE POWER AND VOLTAGE CONTROL ......................................................................... 78 7.1 Introduction ..........................................................................................................................78 7.2 Synchronous Condensers .................................................................................................... 80

8 CONCLUSION ...................................................................................................................................................... 105 9 SUMMARY ............................................................................................................................................................ 107 10 STATUTORY PROVISIONS FOR REACTIVE POWER MANAGEMENT AND VOLTAGE CONTROL ........ 109

10.1 Provision in the Central Electricity Authority (Technical Standard for connectivity to the grid) Regulations 2007 [8]: .......................................................................................................... 109 10.2 Provision in The Indian Electricity Grid Code (IEGC), 2010: ........................................ 109 10.3 The AEGCL Gazette, Extraordinary, February 10, 2005 .............................................. 114

11. BIBLIOGRAPHY: ............................................................................................................................................... 118

List Details.

List 1 International connectivity of NER at 400kV (Charged at 132kV) ...................................... 30 List 2 International Connectivity of NER at 132kV ........................................................................ 30 List 3 +/- 800 kV HVDC Lines Agra-BNC .................................................................................... 30 List 4: 400kV Line Details of North Eastern Region ........................................................................ 30 List 5: 400kV line ( Charged at 220kV ) details of North Eastern Region ....................................... 32 List 6: 400kV line (Charged at 132kV) in North Eastern Region ..................................................... 32 List 7 : 220 kV Line details of North Eastern Region ....................................................................... 32 List 8:132kV Line details of Powergrid in North Eastern Region .................................................... 34 List 9: : 132kV Lines details of NEEPCO in North Eastern Region ................................................... 35 List 10:132kV Line details of AEGCL in North Eastern .................................................................... 36 List 11: 132kV Line details of Manipur in North Eastern Region ...................................................... 37 List 12: 132kV Line details of TSECL in North Eastern region ........................................................ 38 List 13: 132kV Line details of Nagaland in North Eastern Region ................................................... 39 List 14: 132kV Line details of Mizoram in North eastern region ...................................................... 39 List 15: 132kV Line details of MeECL in North Eastern Region ....................................................... 39 List 16: 132kV Line details of AP in North eastern Region ................................................................ 41 List 17: 66kV Line Details of North Eastern region ........................................................................... 41 List 18: Shunt Compensated Lines in North Eastern Region ........................................................... 42 List 19: Shunt Compensated Inter-Regional Lines in North Eastern Region .................................. 43 List 20: Inter State Line details of North Eastern Region ................................................................ 44 List 21: Fixed, Switchable and Convertible Line reactors in North Eastern Region ........................ 46 List 22: Bus Reactors in North Eastern Region ................................................................................ 48


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List 23: Tertiary Reactors on 33kV side of 400/220/33 kV ICTs in North Eastern Region ........... 48 List 24: Substations in North Eastern Region ................................................................................... 51 List 25: Shunt Capacitors details in North Eastern Region ............................................................... 52 List 26: ICTS details of PowerGrid in North Eastern Region ............................................................ 55 List 27: ICTs details of NEEPCO in North Eastern Region ............................................................... 56 List 28: ICTs details of NHPC in North Eastern Region ................................................................... 56 List 29: ICTs details of Arunachal Pradesh in North Eastern Region ............................................... 56 List 30: ICTs details of AEGCL in North Eastern Region.................................................................. 57 List 31: ICTs details of Manipur in North Eastern Region ............................................................... 62 List 32: ICTs details of Meghalaya in North Eastern Region ........................................................... 63 List 33: ICTs details of Mizoram in North Eastern Region .............................................................. 64 List 34: ICTs details of Nagaland in North Eastern Region .............................................................. 65 List 35: ICTs details of TsECL in North Eastern Region ................................................................... 65 List 36: ICTs details of OTPC in North Eastern Region .................................................................... 67 List 37: Transmission/Transformation/VAR Compensation Capacity of North Eastern Region .. 67

List of Figures:

Figure 1 Voltage and Current Waveform ............................................................................................. 7 Figure 2 Power Triangle ...................................................................................................................... 8 Figure 3 Boat Pulled by Horse ............................................................................................................ 9 Figure 4 Direction of Pull .................................................................................................................... 9 Figure 5 Vector Representation of Analogy ........................................................................................ 9 Figure 6 Labyrint Spel ........................................................................................................................ 10 Figure 7 Vector Representation ......................................................................................................... 11 Figure 8 Time frames for voltage stability phenomena ..................................................................... 14 Figure 9 PV curve and Voltage stability margin under different conditions .................................... 15 Figure 10 Average cost of Reactive power technologies .................................................................... 18 Figure 11 NER Grid map..................................................................................................................... 19 Figure 12 . SIL VS Compensation ...................................................................................................... 27 Figure 13 Switching principle of LTC ................................................................................................. 53 Figure 14 HVDC Fundamental components ..................................................................................... 70 Figure 15: Schematic Diagram of HVDC-BNC ................................................................................... 72 Figure 16 Static VAR Compensators (SVC): TCR/TSR, TSC, FC and Mechanically Switched Resistor ............................................................................................................................................... 76 Figure 17 STATCOM topologies: (a) STATCOM based on VSI and CSI (b) STATCOM with storage ............................................................................................................................................................ 76 Figure 18 Series-connected FACTS controllers: (a) TCSR and TSSR; (b) TSSC; (c) SSSC ............... 77 Figure 19 D-Curve of a typical Generator ..........................................................................................78


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List of Tables: Table 1: Reactive power compensation sources ................................................................................. 17 Table 2: Fault level at important Sub-Stations of NER .................................................................... 23 Table 3 : Line Parameters & Surge Impedance Loading of Different Conductor Type ................... 29 Table 4: Equipment preference ......................................................................................................... 49 Table 5: AC Filter Bank at HVDC Agra .............................................................................................. 73 Table 6: AC Filter Bank at HVDC BNC. ............................................................................................. 73 Table 7: Impact of Largest Filter Switching under different HVDC Power order. ........................... 74 Table 8: List of units in NER required to be normally operated with free....................................... 80 Table 9: IEGC operating voltage range ............................................................................................ 112

Capability Curve of Generator in NER: Capability Curve 1: LTPS unit 5, 6, 7 .................................................................................................. 81 Capability Curve 2: NTPS UNIT 1, 2 & 3 ........................................................................................... 82 Capability Curve 3: NTPS UNIT 4..................................................................................................... 83 Capability Curve 4: NTPS UNIT 6 .................................................................................................... 84 Capability Curve 5: LTPS .................................................................................................................. 85 Capability Curve 6: NTPS .................................................................................................................. 86 Capability Curve 7: UMIUM ST I .......................................................................................................87 Capability Curve 8: UMIUM STAGE II............................................................................................. 88 Capability Curve 9: UMIUM STAGE III ........................................................................................... 89 Capability Curve 10: UMIUM STAGE IV .......................................................................................... 90 Capability Curve 11: AGBPP UNIT 5, 6, 7, 8 & 9................................................................................ 91 Capability Curve 12: AGBPP UNIT 1, 2, 3 & 4 .................................................................................. 92 Capability Curve 13: AGTPP .............................................................................................................. 93 Capability Curve 14: DOYANG HEP UNIT 1 .................................................................................... 94 Capability Curve 15: KHANDONG HEP UNIT 2 ............................................................................... 95 Capability Curve 16: KOPILI HEP UNIT 1 ........................................................................................ 96 Capability Curve 17: KOPILI HEP UNIT 2 ........................................................................................ 97 Capability Curve 18: KOPILI HEP ST II ........................................................................................... 98 Capability Curve 19: RANGANADI HEP .......................................................................................... 99 Capability Curve 20: LOKTAK HEP ............................................................................................... 100 Capability Curve 21: ROKHIA UNIT 3, 4 & 6 .................................................................................. 101 Capability Curve 22: ROKHIA & BARAMURA ................................................................................ 102 Capability Curve 23: OTPC PALATANA GTG ................................................................................. 103 Capability Curve 24: OTPC PALATANA STG .................................................................................. 104 Capabilty Curve 25:BgTPP ............................................................................................................... 105


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EXECUTIVE SUMMARY

Quality of power to the stakeholders is the question of the hour worldwide. Enactment of several regulations viz. IE act – 2003, ABT, Open access regulations, IEGC, DSM and several other amendments are in the direction towards improvement of system reliability and power quality.

It is also significant to mention that due to the massive load growth in the country, the existing power networks are operated under greater stress with transmission lines carrying power near their limits. Increase in the complexity of network and being loaded non-uniformly has increased its vulnerability to grid disturbances due to abnormal voltages (High and Low). In the past, reason for many a black outs across the world have been attributed to this cause.

Three objectives dominate reactive power management. Firstly, maintaining adequate voltage throughout the transmission system under normal and contingency conditions. Secondly, minimizing congestion of real – power flows. Thirdly, minimizing real – power losses. Also with dynamic ATCs, var compensation, congestion charges, if not seriously thought, it may have serious commercial implications in times to come due to the amount of bulk power transfer across the country. Highlights of rolling Year of NER grid include commercial operation of 132 kV Surajmaninagar-Comilla D/C line and commissioning of second Pole of BNC-Agra HVDC. Surajmaninagar comilla is international connection between india and Banladesh , Surajmaninagar in Tripura india and comilla located in Bangladesh. NTPC first unit of capacity 250 MW declared commercially operational in the month of April. Other major elements commissioned during current year is 2x100 MVA 220/132 kV ICTs at Sonabil (AEGCL) , 132 kV Balipara (PG)- Sonabil (AEGCL), 132 kV Silchar (PG)- Hailakandi (AEGCL) , 2x25 MVA 132/33 kV Transformers at Hailakandi (AEGCL) , 132 kV Dullavcherra (AEGCL)- Hailakandi (AEGCL) and 400/132 kV 125 MVA ICT 2 at Palatana first time test charged. Palatana ICT commissioning shall fulfill the N-I contingency requirement of existing 125 MVA ICT at Palatana and also increase reliability of Auxillary supply of Palatana Generation. During the Year LILO configuration was done for 400kV Bangaigaon-New Siliguri III & IV and 220kV Salakati-Birpara at Alipurduar substation, which is inter Regional connectivity between ER and NER Grid.


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Comissioning of Hailakandi substation has strengthened South Assam connectivity with NER grid. Sonabil Substation commissioning has improved connectivity in central Assam. With the commissioning of these elements state network connectivity with NER grid has further been strengthened. With the increase in controllability compared to earlier years, grid operation has been smooth and grid parameters were maintained within the prescribed IEGC limits.

This manual is in continuation to the previous edition for understanding the basics of reactive power and its management towards voltage control, its significance and consequences of inadequate reactive power support. It also includes details of reactive power support available at present and efforts by planners from future perspective in respect of NER grid.


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1 REACTIVE POWER MANAGEMENT AND VOLTAGE CONTROL

1.1 Introduction

1.1.1 hat is Reactive Power ? Reactive power is a concept used by engineers to

describe the background energy movement in an Alternating Current (AC) system arising from the production of electric and magnetic fields.

These fields store energy which changes through each AC cycle. Devices which store energy by virtue of a magnetic field produced by a flow of current are said to absorb reactive power (viz. transformers, Reactors) and those which store energy by virtue of electric fields are said to generate reactive power (viz. Capacitors).

1.1.2 Power flows, both actual and potential, must be carefully controlled for a power system to operate within acceptable voltage limits. Reactive power flows can give rise to substantial voltage changes across the system, which means that it is necessary to maintain reactive power balances between sources of generation and points of demand on a 'zonal basis'. Unlike system frequency, which is consistent throughout an interconnected system, voltages experienced at points across the system form a "voltage profile" which is uniquely related to local generation and demand at that instant, and is also affected by the prevailing system network arrangements.

1.1.3 In an interconnected AC grid, the

voltages and currents alternate up and down 50 times per second (not

necessarily at the same time). In that sense, these are pulsating quantities. Because of this, the power being transmitted down a single line also “pulsates” - although it goes up and down 100 times per second rather than 50.

W

Figure 1 Voltage and Current Waveform


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1.1.4 To distinguish reactive power from real power, we use the reactive power unit called “VAR” - which stands for Volt-Ampere-Reactive (Q). Normally electric power is generated, transported and consumed in alternating current (AC) networks. Elements of AC systems supply (or produce) and consume (or absorb or lose) two kinds of power: real power and reactive power.

1.1.5 Real power accomplishes useful work (e.g., runs motors and lights lamps). Reactive power supports the voltages that must be controlled for system reliability. In AC power networks, while active power corresponds to useful work, reactive power supports voltage magnitudes that are controlled for system reliability, voltage stability, and operational acceptability.

1.1.6 VAR Management? It is defined as the control of generator voltages, variable transformer tap settings, compensation, switchable shunt capacitor and reactor banks plus allocation of new shunt capacitor and reactor banks in a manner that best achieves a reduction in system losses and/or voltage control.

1.1.7 Although active power can be transported over long distances, reactive power is

difficult to transmit, since the reactance of transmission lines is often 4 to 10 times higher than the resistance of the lines. When the transmission system is heavily loaded, the active power losses in the transmission system are also high. Reactive power (vars) is required to maintain the voltage to deliver

active power (watts) through transmission lines. When there is not enough reactive power, the voltage sags down and it is not possible to push the power demanded by loads through the lines. Reactive power supply is necessary in the reliable operation of AC power systems. Several recent power outages worldwide may have been a result of an inadequate reactive power supply which subsequently led to voltage collapse.

1.1.8 Voltage and current may not pulsate up and down at the same time. When the

voltage and current do go up and down at the same time, only real power is transmitted. When the voltage and current go up and down at different times, reactive power is also gets transmitted. How much reactive power and which direction it is flowing on a transmission line depend on how different these two items are. Although AC voltage and current pulsate at the same frequency, they peak at a different time. Power is the algebraic product of voltage and current. Over a cycle, power has an average value, called real power (P), measured in volt-amperes, or watts. There is also a portion of power with zero average value that

Figure 2 Power Triangle


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is called reactive power (Q), measured in volt-amperes reactive, or vars. The total power is called apparent power or Complex power, measured in volt-amperes, or VA.

1.2 Analogy of Reactive Power

1.2.1 Why an analogy? Reactive Power is an essential aspect of the electricity system, but one that is difficult to comprehend by a lay man. The horse and the boat analogy best describe the Reactive Power aspect.

Visualize a boat on a canal, pulled by a horse on the bank of the canal.

In actual the horse is not in front of the boat to do a meaningful work of pulling it in a straight path. Due to the balancing compensation by the rudder of the boat, the boat is made to move in a straight manner rather deviating towards the bank. This is in line with the understanding of the reactive power.

W

Figure 4 Direction of Pull

Figure 5 Vector Representation of Analogy

Figure 3 Boat Pulled by Horse


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1.2.1 In the horse and boat analogy, the horse’s objective (real power) is to move the boat straightly. The fact that the rope is being pulled from the flank of the horse and not straight behind it, limits the horse’s capacity to deliver real work of moving straightly. Therefore, the power required to keep the boat steady in navigating straightly is delivered by the rudder movement (reactive power). Without reactive power there can be no transfer of real power, likewise without the support of rudder, the boat cannot move in a straight line.

1.2.2 Reactive power is like the bouncing up and down that happens when we walk

on a trampoline. Because of the nature of the trampoline, that up-down bouncing is an essential part of our forward movement across the trampoline, even though it appears to be movement in the opposite direction.

1.2.3 Reactive power and real power work together in the way that’s illustrated very

well by the labyrinth puzzle, LABYRINTSPEL:

The description of the puzzle begins to show why this game represents the relationship between real and reactive power:

The intent is to manipulate a steel ball (1.2cm in diameter) through the maze by rotating the knobs – without letting the ball fall into one of the holes before it reaches the end of the maze. If a ball does fall prematurely into a hole, a slanted floor inside the box returns the ball to the user in the trough on the lower right corner of the box.

1.2.4 The Objective is to twist the two knobs to adjust the angle of the platform in two directions, in order to keep the ball rolling through the maze without falling into any holes. Those twists are REACTIVE POWER, which helps propel the real power through to its ultimate goal, which is delivery to the user. Without reactive power, ball falls into holes along the way, which are NETWORK failures.

1.2.5 Both of these examples illustrate how important it is to understand the system

and how it works in order to meet our objectives effectively. In the LABYRINTSPEL game, if the structure of the system is not taken into account, winning would be really easy because one knob would be turned all the way in

Figure 6 Labyrint Spel

http://gamesmuseum.uwaterloo.ca/puzzles/maze/


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one direction, and the other knob all the way in the other direction, and the ball would merely roll across the platform. If that’s the model how electricity works, then that would deliver the electrons to the end user in the form of real power. But in the game, on the trampoline, and in the electric power network, the system has more going on that means it’s essential to do things that seem counterintuitive, like bouncing up and down on the trampoline or turning the platform in the game towards west to avoid the hole to the east, even though we have to go east to win.

1.2.6 In electric power, the counterintuitive thing about reactive power is to use some

power along the path to balance the flow of electrons and the circuits. Otherwise, the electricity just flows from the generator to the largest consumer (that’s Kirchhoff’s law, basically). In this sense, reactive power is like water pressure in a water network.

1.2.7 LABYRINTSPEL game and the trampoline are good examples that they capture

the fact that mathematically, real power and reactive power are pure conjugates.

1.3 Understanding Vectorally

1.3.1 In practice circuits are invariably combinations of resistance, inductance and capacitance. The combined effect of these impedances to the flow of current is most easily assessed by expressing the power flows as vectors that show the angular relationship between the powers waveforms associated with each type of impedance. Figure 7 shows how the vectors can be resolved to determine the net capacity of the circuit needed to transfer the power requirements of the connected equipment.

1.3.2 The useful power that can be drawn

from the electricity distribution system is represented by the vertical vector in the diagram and is measured in kilowatts (kW).The reactive or wattless power that is a consequence of the inductive load in the circuit is represented by the horizontal vector to the right and the reactive power attributable to the circuit capacitance by

Figure 7 Vector Representation


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the horizontal vector to the left. These are measured in kilovars (kVAr).

1.3.3 The resolution of these vectors, which is the diagonal vector in the diagram is the capacity required to transmit the active power, and is measured in kilovolts-ampere (kVA). The ratio of the kW to kVA is the cosine of the angle in the diagram shown as theta, and is referred to as the “power factor”.

1.3.4 When the net impedance of the circuit is solely resistance, so that the

inductance and capacitance exactly cancel each other out, then the angle theta becomes zero and the circuit has a power factor of unity. The circuit is now operating at its highest efficiency for transferring useful power. However, as a net reactive power emerges the angle theta starts to increase and its cosine falls.

1.3.5 At low power factors the magnitude of the kVA vector is significantly greater

than the real power or kW vector. Since distribution assets such as cables, lines and transformers must be sized to meet the kVA requirement, but the useful power drawn by the customer is the kW component, a significant cost emerges from having to over-size the distribution system to accommodate the substantial amount of reactive power that is associated with the active power flow.

1.4 Voltage Stability

1.4.1 Power flows, both actual and potential, must be carefully controlled for a power system to operate within acceptable voltage limits and vice versa. Not only is reactive power necessary to operate the transmission system reliably, but it can also substantially improve the efficiency with which real power is delivered to customers. Increasing reactive power production at certain locations (usually near a load center) can sometimes alleviate transmission constraints and allow cheaper real power to be delivered into a load pocket.

1.4.2 Voltage control (keeping voltage within defined limits) in an electric power

system is Important for proper operation of electric power equipment and saving it from imminent damage, to reduce transmission losses and to maintain the ability of the system to withstand disturbances and prevent voltage collapse. In general terms, decreasing reactive power causes voltages to fall, while increasing reactive power causes voltages to rise. A voltage collapse occurs when the system is trying to serve much more load than the voltage can support.


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1.4.3 As voltage drops, current must increase to maintain the power

supplied, causing the lines to consume more reactive power and the voltage to drop further. If current increases too much, transmission lines trip, or go off-line, overloading other lines and potentially causing cascading

failures. If voltage drops too low, some generators will automatically disconnect to protect themselves.

1.4.4 Usually the causes of under – voltages are:

• Overloading of supply transformers • Inadequate short circuit level in the point of supply • Excessive voltage drop across a long feeder • Poor power factor of the connected load • Remote system faults , while they are being cleared • Interval in re-closing of an auto-reclosure • Starting of large HP induction motors

1.4.5 If the declines continue, these voltage reductions cause additional elements to

trip, leading to further reduction in voltage and loss of load. The result is a progressive and uncontrollable decline in voltage, all because the power system is unable to provide the reactive power required to supply the reactive power demand.

1.5 Voltage Collapse 1.5.1 When voltages in an area are significantly low or blackout occurs due to the

cascading events accompanying voltage instability, the problem is considered to be a voltage collapse phenomenon. Voltage collapse normally takes place when a power system is heavily loaded and/or has limited reactive power to support the load. The limiting factor could be the lack of reactive power (SVC and generators hit limits) production or the inability to transmit reactive power through the transmission lines.

1.5.2 The main limitation in the transmission lines is the loss of large amounts of

reactive power and also line outages, which limit the transfer capacity of reactive power through the system.

1.5.3 In the early stages of analysis, voltage collapse was viewed as a static problem

but it is now considered to be a non linear dynamic phenomenon. The dynamics


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in power systems involve the loads, and voltage stability is directly related to the loads. Hence, voltage stability is also referred to as load stability.

1.5.4 There are other factors which also contribute to voltage collapse, and

are as below: • Increase in load • Action of tap changing transformers • Load recovery dynamics

All these factors play a significant part in voltage collapse as they effect the transmission, consumption, and generation of reactive power.

Usually voltage stability is categorized into two parts

• Large disturbance voltage stability • Small disturbance voltage stability

1.5.5 When a large disturbance occurs, the ability of the system to maintain acceptable voltages falls due to the impact of the disturbance. Ability to maintain voltages is dependent on the system and load characteristics, and the

Figure 8 Time frames for voltage stability phenomena


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interactions of both the continuous and the discrete controls and protections. Similarly, the ability of the system to maintain voltages after a small perturbation i.e. incremental change in load is referred to as small disturbance voltage stability. It is influenced by the load characteristics, continuous control and discrete controls at a given instant of time.

1.6 Proximity to Instability 1.6.1 Static voltage instability is mainly associated with reactive power

imbalance. Thus, the loadability of a bus in a system depends on the reactive power support that the bus can receive from the system. As the system approaches the maximum loading point or voltage collapse point, both real and reactive power losses increase rapidly.

1.6.2 Therefore, the reactive power supports have to be locally adequate. With static

voltage stability, slowly developing changes in the power system occur that eventually lead to a shortage of reactive power and declining voltage.

1.6.3 This phenomenon can be seen from a

plot of power transferred versus voltage at the receiving end. These plots are popularly referred to as P–V curves or ‘Nose’ curves. As power transfer increases, the voltage at the receiving end decreases. In the fig(9) eventually, a critical (nose) point, the point at which the system reactive power is out of usage, is reached where any further increase in active power transfer will lead to very rapid decrease in voltage magnitude.

1.6.4 Before reaching the critical point, a large voltage drop due to heavy reactive power losses is observed. The only way to save the system from voltage collapse is to reduce the reactive power load or add additional reactive power prior to reaching the point of voltage collapse.

Knee point

∆v

Figure 9 PV curve and Voltage stability margin under different conditions


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These are curves drawn between V and P of a critical bus at a constant load power factor.

These are produced by using a series of power flow solutions for different load levels.

At the knee point or the nose point of the V-P curve, the voltage drops rapidly with an increase in the load demand.

Power flow solution fails to converge beyond this limit which indicates the instability.

1.7 Reactive Reserve Margin 1.7.1 The amount of unused available capability of reactive power static as well as

dynamic in the system (at peak load for a utility system) as a percentage of total capability is known as Reactive reserve margin.

1.7.2 Voltage collapse normally occurs when sources producing reactive power reach

their limits i.e. generators, SVCs or shunt reactors, and there is not much reactive power to support the load. As reactive power is directly related to voltage collapse, it can be used as a measure of voltage stability margin.

1.7.3 The voltage stability margin can be defined as a measure of how close the

system is to voltage instability, and by monitoring the reactive reserves in the power system, proximity to voltage collapse can be monitored.

1.7.4 In case of reactive reserve criteria, the reactive power reserve of an individual or

group of VAr sources must be greater than some specified percentage (x %) of their reactive power output under all contingencies. The precincts where reactive power reserves were exhausted would be identified as critical areas.

1.7.5 Reactive power requirements over and above those which occur naturally are

provided by an appropriate combination of reactive source/devices which are normally classified as static and dynamic devices.

STATIC SOURCES: Static sources are typically transmission and distribution

equipments such as Capacitors and Reactors that are relatively static and can respond to the changes in voltage – support requirements only slowly and in discrete steps. Devices are inexpensive, but the associated switches, control, and communications, and their maintenance, can amount to as much as one third of the total operations and maintenance budget of a distribution system.


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DYNAMIC SOURCES: It includes pure reactive power compensators like synchronous condensers, Synchronous generators and solid-state devices such as FACTS, SVC, STATCOM, D-VAR, and SuperVAR which are normally dynamic and can respond within cycles to changing reactive power requirement. These are typically considered as transmission service devices.

1.7.6 Static devices typically have lower capital costs than dynamic devices, and from

a system point of view, they are used to provide normal or intact-system voltage support and to adapt to slowly changing conditions, such as daily load cycles and scheduled transactions. By contrast, dynamic reactive power sources must be deployed to allow the transmission system to respond to rapidly changing conditions on the transmission system, such as sudden loss of generators or transmission facilities. An appropriate combination of both static and dynamic resources is needed to ensure reliable operation of the transmission system at an appropriate level of costs.

1.7.7 Reactive power absorption occurs when current flows through an inductance.

Inductance is found in transmission lines, transformers, and induction motors etc. The reactive power absorbed by a transmission line or transformer is proportional to the square of the current.

Sources of Reactive Power Sinks of Reactive Power Static: Shunt Capacitors Filter banks Under ground cables Transmission lines (lightly

loaded) Fuel cells PV systems

Dynamic: Synchronous Generators Synchronous Condensers FACTS (e.g.,SVC,STATCOM)

Transmission lines (Heavily loaded)

Transformers Shunt Reactors Synchronous machines FACTS (e.g.,SVC,STATCOM) Induction generators (wind plants) Loads • Induction motors (Pumps, Fans

etc) • Inductive loads (Arc furnace etc)

Table 1: Reactive power compensation sources


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1.7.8 A transmission line also has capacitance. When a small amount of current is

flowing, the capacitance dominates, and the lines have a net capacitive effect which raises voltage. This happens at night when current flows/Load is low. During the day, when current flow/load is high, inductive effect is greater than the capacitance, and the voltage sags.

Figure 10 Average cost of Reactive power technologies


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1.8 NER GRID – Overview

1.8.1 NER grid with a maximum peak requirement of around 2474 MW and installed capacity of 3620 MW caters to the seven north eastern states. It is synchronously connected with ER Grid through 400 kV QUAD/C BONGAIGAON – NEW SILIGURI, 220 kV D/C BIRPARA – SALAKATI and internationally through 132 kV SALAKATI – GELYPHU(Bhutan) and 132 kV Rangia - Deothang. Also, it is connected to NR grid through ±800kV HVDC Biswanath Charali-Agra link. The bottle neck of operating the NER grid arises because of the brittle back bone network of about 8016 Ckt Kms of 132 KV lines, 4091 Ckt Kms of 400 KV lines and 3197 Ckt Kms of 220 KV lines compared to other regional grids.

1.8.2 With Commissioning of first multi-terminal HVDC between Biswanath Charali and

Agra , NER grid is directly connected with NR grid by this HVDC link. The capacity of each terminal at Biswanath Charali(NER) and Alipurduar (ER) is 3000 MW and at Agra it is 6000 MW. This HVDC shall be operating at ± 800 kV voltage.

Figure 11 NER Grid map


Page 20 of 119

1.8.3 Highlights of NER grid for current year include commercial operation of 132 kV

Surajmaninagar-Comilla D/C line and commissioning of second Pole of BNC-Agra HVDC. Surajmaninagar comilla is international connection between india and Bangladesh , Surajmaninagar in Tripura india and comilla located in Bangladesh. Other major elements commissioned during current year is 2x100 MVA 220/132 kV ICTs at Sonabil (AEGCL) , 132 kV Balipara (PG)- Sonabil (AEGCL), 132 kV Silchar (PG)- Hailakandi (AEGCL) , 2x25 MVA 132/33 kV Transformers at Hailakandi (AEGCL) , 132 kV Dullavcherra (AEGCL)- Hailakandi (AEGCL) and 400/132 kV 125 MVA ICT 2 at Palatana first time test charged. Palatana ICT commissioning shall fulfill the N-I contingency requirement of existing 125 MVA ICT at Palatana and also increase reliability of Auxillary supply of Palatana Generation.

1.8.4 Almost 50% of the total NER load is spread out in 132 kV pocket of southern part of NER which were without the direct support of major EHV trunk lines. This part of the network was highly sensitive and was susceptible to grid disturbance in the past and demanded more operational acumen. Increase in the loading of major 132 kV trunk lines, in particular 132 kV DIMAPUR – IMPHAL S/C,132 kV JIRIBAM – LOKTAK S/C and 132 kV BADARPUR – KHLIEHRIAT S/C in peak hours has led to many a grid incidents in the past in the form of cascade tripping accompanied by voltage sag. However, with system augmentation grid incidence in this part of the grid has become a matter of past.

1.8.5 Relationship between frequency and voltage is a well-known fact. Studies have

revealed that though voltage is a localized factor, it is directly affected by the frequency which is a notional factor. Any lopsidedness in the demand/generation side leading to fluctuations in NEW grid frequency affects NER grid immensely, in particular the voltage profile of the grid, leading to sagging and swelling of voltage heavily during such occasions. Ironically, NER was synchronously connected with NEW grid for stretching the transmission capability to reduce the load – generation mismatch of the country.

1.8.6 FSC’s have been integrated with the NER system in the 400 kV Balipara – Bongaigaon

III & IV at Balipara end.

1.8.7 Presently NER Grid is supported by 2884 MVAr from shunt reactors and 273 MVAr from shunt capacitors spread across the region.


Page 21 of 119

1.8.8 Skewness in the location of hydro stations and load centers in NER is another obstacle which aggravates the voltage problem further. Lines are long and pass through difficult terrains to the load centers. Northern part of NER grid which is well supported by some strong 400 KV and 220 KV network faces high voltage regime during lean hydro period as the corridor is not fully utilized and is usually lightly loaded. Supports from hydro stations in condenser mode are not available for containing low voltage conditions. D curve optimization is yet to be realized fully due to technical glitches.

1.8.9 Reactive power management and voltage control are two aspects of a single activity

that both supports reliability and facilitates commercial transaction across transmission network. Controlling reactive power flow can reduce losses and congestion on the transmission system.

1.8.10 Operationally in NER, Voltage is normally controlled by managing production and absorption of reactive power in real time :

Switching in and out of Line reactance compensators such as capacitors and

shunt reactors (Line/Bus Reactors) as and when system demands in co-operation with the constituents and the CTU.

Circuit switching: Mostly one circuit of the lightly loaded d/c line is kept open keeping in mind the n-1 criterion during high voltage and high frequency period. Voltage differences as well as fault level of stations are taken into account before any switching operation of circuits.


Page 22 of 119

Fault levels of major substation in NER are as below:

Bus

Jul'16 Off Peak (Operational Case) Jul'16 Peak (Operational Case)

3 ϕ Fault Current in kA

3 ϕ Fault MVA

3 ϕ Fault Current in

kA 3 ϕ Fault MVA

400 kV Substations

Bongaigaon 13.33 9233 13.93 9688 Balipara 7.64 5295 8.10 5612 Silchar 7.10 4922 7.13 4938

Palatana 7.09 4915 7.17 4964 Misa 6.75 4679 6.90 4781

Azara (Mirza) 6.60 4570 6.92 4797 Byrnihat 6.52 4514 6.90 4778

BiswanthChariali 6.45 4467 6.57 4555

Ranganadi 4.36 3024 4.63 3210

220 kV Substations

Misa 13.56 5168 14.38 5482 Samaguri 10.63 4050 11.10 4229 Byrnihat 9.85 3755 10.19 3884

Kopili 9.62 3667 9.95 3791 Salakati 9.35 3564 9.56 3641

BTPS 9.16 3491 9.89 3771 Azara (Mirza) 9.09 3464 9.27 3532

Balipara 8.83 3363 9.20 3504 Agia 7.09 2702 7.26 2765

Sarusajai 6.30 2402 6.42 2447 AGBPP

(Kathalguri) 5.74 2189 5.83 2222

Boko 5.54 2109 5.83 2223 Mariani (AS) 5.42 2065 5.57 2123

Tinsukia 5.06 1927 5.27 2009


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Dimapur (PG) 5.02 1913 5.22 1990 NTPS 4.25 1632 4.39 1672 Langpi 3.92 1493 3.95 1506

Mariani (PG) 3.78 1439 3.86 1471

Mokokchung(PG) 3.23 1234 3.30 1259

132 kV Substations

Silchar 13.32 3044 13.19 2834 Agartala 11.15 2541 11.10 2416 Badarpur 11.11 2540 8.83 2343

AGTPP (RC Nagar) 10.36 2369 8.83 2230 Surjamnagar 10.05 2298 8.17 2216 Monarchawk 8.83 2021 8.95 1760 Kumarghat 8.28 1894 8.37 1683

Dimapur (PG) 7.88 1803 7.10 1595 Khandong 7.59 1736 3.40 1196

Imphal (PG) 7.17 1638 7.71 1177 Balipara 5.24 1199 6.01 1017 Loktak 5.02 1147 5.43 997

Jiribam (PG) 4.91 1122 5.16 991 Khlierihat (PG) 4.73 1081 4.86 983

Doyang 4.65 1064 4.71 928 Nirjuli 4.52 1034 4.74 874 Aizawl 2.87 657 2.89 648 Haflong 2.85 653 2.75 587

Table 2: Fault level at important Sub-Stations of NER Note: (i) HVDC BNC Agra assumed to be importing 150 MW from Agra. (ii) Gohpur loads assumed to be fed from 132 kV BiswanathChariali (PG)

The generating units provide the basic means of voltage control: The

automatic voltage regulators (AVR) control field excitation to maintain the scheduled voltage levels at the terminals of the generators. In real time


Page 24 of 119

operation, connected generation should never be on reactive generation or absorption limits.

By generation re-dispatch/rescheduling. Regulating voltage with the help of OLTC’s. By load staggering/shedding.

1.9 Reliability Improvement Due to Local Voltage Regulation

1.9.1 Local voltage regulation to a voltage schedule supplied by the utility can have a very beneficial effect on overall system reliability, reducing the problems caused by voltage dips on distribution circuits such as dimming lights, slowing or stalling motors, dropout of contactors and solenoids, and shrinking television pictures.

1.9.2 In past years a voltage drop would inherently reduce load, helping the situation.

Light bulbs would dim and motors would slow down with decreasing voltage. Dimmer lights and slower motors typically draw less power, so the situation was in a certain sense self-correcting. With modern loads, this situation is changing.

1.9.3 Today many incandescent bulbs are being replaced with compact fluorescent

lights, LED lamps that draw constant power as voltage decreases, and motors are being powered with adjustable-speed drives that maintain a constant speed as voltage decreases. In addition, voltage control standards are rather unspecific, and there is a tremendous opportunity for an improvement in efficiency and reliability from better voltage regulation. Capacitors supply reactive power to boost voltage, but their effect is dramatically diminished as voltage dips.

1.9.4 Capacitor effectiveness is proportional to the square of the voltage, so at 80%

voltage, capacitors are only 64% as effective as they are at normal conditions. As voltage continues to drop, the capacitor effect falls off until voltage collapses. The reactive power supplied by an inverter is dynamic, it can be controlled very rapidly, and it does not drop off with a decrease in voltage. Distribution systems that allow customers to supply dynamic reactive power to regulate voltage could be a tremendous asset to system reliability and efficiency by expanding the margin to voltage collapse.


Page 25 of 119

2 TRANSMISSION LINES AND REACTIVE POWER COMPENSATION

2.1 Introduction 2.1.1 In moving power from generators to loads, the transmission network introduces

both real and reactive losses. Housekeeping loads at substations (such as security lighting and space conditioning) and transformer excitation losses are roughly constant (i.e., independent of the power flows on the transmission system). Transmission-line losses, on the other hand, depend strongly on the amount of power being transmitted.

2.1.2 Real-power losses arise because aluminum and copper (the materials most often

used for transmission lines) are not perfect conductors; they have resistance. The consumption of reactive power by transmission lines increases with the square of current i.e., the transmission of reactive power requires an additional demand for reactive power in the system components.

2.1.3 The reactive-power nature of transmission lines is associated with the geometry of

the conductors themselves (primarily the radius of the conductor) and the geometry of the conductor configuration (the distances between each conductor and ground and the distances among conductors).

2.1.4 The reactive-power behavior of transmission lines is complicated by their inductive

and capacitive characteristics. At low line loadings, the capacitive effect dominates, and generators and transmission-related reactive equipment must absorb reactive power to maintain line voltages within their appropriate limits. On the other hand, at high line loadings, the inductive effect dominates, and generators, capacitors, and other reactive devices must produce reactive power

2.1.5 The thermal limit is the loading point (in MVA) above which real power losses in

the equipment will overheat and damage the equipment. Most transmission elements (e.g., conductors and transformers) have normal thermal limits below which the equipment can operate indefinitely without any damage. These types of equipment also have one or more emergency limits to which the equipment can be loaded for several hours with minimal reduction in the life of the equipment.

2.1.6 If uncompensated, these line losses reduce the amount of real power that can be transmitted from generators to loads. Transmission-line capacity decreases as the


Page 26 of 119

line length increases if there is no voltage support (injection or absorption of reactive power) on the line. At short distances, the line’s capacity is limited by thermal considerations; at intermediate distances the limits are related to voltage drop; and beyond roughly 300 to 350 miles, stability limits dominate.

2.2 Surge Impedance Loading (SIL) 2.2.1 Transmission lines and cables generate and consume reactive power at the

same time. The reactive power generation is almost constant, because the voltage of the line is usually constant, and the line’s reactive power consumption depends on the current or load connected to the line that is variable. So at the heavy load conditions transmission lines consume reactive power, decreasing the line voltage, and in the low load conditions – generate, increasing line voltage.

2.2.2 The case when line’s reactive power produced by the line capacitance is equal to

the reactive power consumed by the line inductance is called natural loading or surge impedance loading (SIL) , meaning that the line provides exactly the amount of MVAr needed to support its voltage. The balance point at which the inductive and capacitive effects cancel each other is typically about 40% of the line’s thermal capacity. Lines loaded above SIL consume reactive power, while lines loaded below SIL supply reactive power.

2.2.3 A 400 kV, line generates approximately 55 MVAR per 100 km/Ckt, when it is

idle charged due to line charging susceptance. This implies a 300 km line generates about 165 MVAR when it is idle charged.

2.3 Shunt Compensation in Line 2.3.1 Normally there are two types of shunt reactors – Line reactor and bus reactor.

Line reactor’s functionality is to avoid the switching and load rejection over voltages whereas Bus reactors are used to avoid the steady state over voltage during light load conditions.

2.3.2 The degree of compensation is decided by an economic point of view between

the capitalized cost of compensator and the capitalized cost of reactive power from supply system over a period of time. In practice a compensator such as a


Page 27 of 119

bank of capacitors (or inductors) can be divided into parallel sections, each Switched separately, so that discrete changes in the compensating reactive power may be made, according to the requirements of the load.

2.3.3 Reasons for the application of shunt capacitor units are :

Increase voltage level at the load Improves voltage regulation if the capacitor units are properly switched. Reduces I2R power loss in the system because of reduction in current. Increases power factor of the source generator. Decrease kVA loading on the source generators and circuits to relieve an

overloaded condition or release capacity for additional load growth. By reducing kVA loading on the source generators additional kilowatt

loading may be placed on the generation if turbine capacity is available.

2.4 Line loading as function of Line Length and Compensation

2.4.1 The operating limits for transmission lines may be taken as minimum of thermal ratingof conductors and the maximum permissible line loadings derived from St. Clair’s curve. SILgiven in table above is for uncompensated line. If k is the compensation then:

• For a shunt compensated line:

SIL modified =SIL x √ (1-k)

• For a series compensated line: SIL modified=SIL/ √ (1- k)

Figure 12 . SIL VS Compensation


Page 28 of 119

Further to take into account the line length one needs to multiple the modified SIL with the multiplying factor derived from St. Clair's curve.The derived steady state limit for a line would be = SIL modified x factor from St. Clair's curve.


Page 29 of 119

Table 3 : Line Parameters & Surge Impedance Loading of Different Conductor Type


Page 30 of 119

List 1 International connectivity of NER at 400kV (Charged at 132kV)

SR. NO

. FROM TO UTILITY KM CKT CONDUCTOR

1 Comilla Surajmani Nagar

POWERGRID 47 1 ACSR Twin Moose

2 Comilla Surajmani Nagar

POWERGRID 47 2 ACSR Twin Moose

List 2 International Connectivity of NER at 132kV

SR. NO


1 Gelyphu(BHU)

Salakati(IND)

POWERGRID 49.2 1 ACSR Panther

2 Motonga(Bhu)

Rangia(IND) AEGCL 49 2 ACSR Panther

List 3 +/- 800 kV HVDC Lines Agra-BNC

SR. NO


1 Agra Biswanath Charali

POWERGRID 1728 1 Hexa Lapwing

2 Agra Biswanath Charali

POWERGRID 1728 2 Hexa Lapwing

List 4: 400kV Line Details of North Eastern Region SR. NO.

FROM TO UTILITY KM CKT CONDUCTO

R

1 BALIPARA MISA POWERGRID 95.4 1

ACSR MOOSE/AACS

R

2 BALIPARA MISA POWERGRID 95.4 2

ACSR MOOSE/AACS

R

3 BALIPARA

BISWANATH CHARIALI

POWERGRID 65 1 ACSR TWIN

MOOSE


Page 31 of 119

4 BALIPARA

BISWANATH CHARIALI POWERGRID 65 2

ACSR TWIN MOOSE

5 BALIPARA

BISWANATH CHARIALI


MOOSE

6 BALIPARA

BISWANATH CHARIALI


MOOSE

7 RANGANADI

BISWANATH CHARIALI

POWERGRID 204 1

ACSR TWIN MOOSE

8 RANGANADI

BISWANATH CHARIALI

POWERGRID 204 2

ACSR TWIN MOOSE

9 BONGAIGAON BALIPARA POWERGRID 289.8 1

ACSR TWIN MOOSE


ACSR TWIN MOOSE


AAAC QUAD MOOSE


AAAC QUAD MOOSE

13 BONGAIGAON BTPS POWERGRID 3.1 1 TWIN MOOSE

14 BONGAIGAON BTPS POWERGRID 3.1 2 TWIN MOOSE

15 BONGAIGAON

NEW SILIGURI (BINAGURI)


MOOSE

16 BONGAIGAON

NEW SILIGURI (BINAGURI)


MOOSE

17 BONGAIGAON ALIPURDUAR POWERGRID 106 3

AAAC QUAD MOOSE

18 BONGAIGAON ALIPURDUAR POWERGRID 106 4

AAAC QUAD MOOSE

19 BYRNIHAT SILCHAR NETCL

217.14

1 ACSR TWIN

MOOSE

20 PALLATANA SILCHAR NETCL 246 1

ACSR TWIN MOOSE

21 PALLATANA SILCHAR NETCL 246 2

ACSR TWIN MOOSE

22 AZARA SILCHAR NETCL 264 1

ACSR TWIN MOOSE

23 AZARA BANGAIGAON NETCL 118 1

ACSR TWIN MOOSE

24 BYRNIHAT BANGAIGAON NETCL 167 1

ACSR TWIN MOOSE


Page 32 of 119

List 5: 400kV line ( Charged at 220kV ) details of North Eastern Region

SR. NO

. FROM TO UTILITY KM

CKT

CONDUCTOR

1 MARIANI KATHALGURI

POWERGRID 162.9 1 ACSR TWIN

MOOSE

2 MISA NEW MARIANI


MOOSE

3 MISA MARIANI POWERGRID 220.0 1 ACSR TWIN

MOOSE

4 NEW MARIANI

KATHALGURI


MOOSE List 6: 400kV line (Charged at 132kV) in North Eastern Region SR. NO. FROM TO UTILITY KM CK

T CONDUCTOR

1 PALATANA SURJAMAN

INAGAR POWERGRID 37 1

ACSR TWIN MOOSE

2 SILCHAR IMPHAL POWERGRID 166.5 1 ACSR TWIN

MOOSE

3 SILCHAR IMPHAL POWERGRID 166.5 2 ACSR TWIN

MOOSE

4 SILCHAR PK-BARI POWERGRID 127.2 1 ACSR TWIN

MOOSE

5 SILCHAR PK-BARI POWERGRID 127.2 2 ACSR TWIN

MOOSE List 7 : 220 kV Line details of North Eastern Region

SR. NO


1 AGIA AZARA AEGCL 107 1 AAAC ZEBRA 2 AGIA BOKO AEGCL 70.0 1 AAAC ZEBRA 3 AGIA BTPS AEGCL 67.0 1 AAAC ZEBRA 4 AGIA BTPS AEGCL 67.0 2 AAAC ZEBRA 5 AZARA BOKO AEGCL 38 1 AAAC ZEBRA


Page 33 of 119

6 AZARA SARUSAJAI AEGCL 24 1 AAAC ZEBRA 7 AZARA SARUSAJAI AEGCL 24 2 AAAC ZEBRA 8

BALIPARA SONABIL AEGCL/POWERGR

ID 10 1 ACSR ZEBRA

9 SONABIL SAMAGURI AEGCL 56 1 ACSR ZEBRA 9 BONGAIGAO

N SALAKATI POWERGRID 5.4 1 SINGLE ZEBRA

10 DEOMALI

KATHALGURI

ARUNACHAL PRADESH

19.0 1 SINGLE ZEBRA

11 KATHALGURI

TINSUKIA AEGCL 22.0 1 SINGLE ZEBRA

12 KATHALGURI

TINSUKIA AEGCL 22.0 2 SINGLE ZEBRA

13 MISA DIMAPUR POWERGRID 121.9 1 ACSR ZEBRA 14 MISA DIMAPUR POWERGRID 121.9 2 ACSR ZEBRA 15 MISA KOPILI POWERGRID 72.8 1 ACSR ZEBRA 16 MISA KOPILI POWERGRID 72.8 2 ACSR ZEBRA 17 MISA KOPILI POWERGRID 75.9 3 AAAC ZEBRA 18 MISA BYRNIHAT MeECL 115.0 1 SINGLE ZEBRA 19 MISA BYRNIHAT MeECL 115.0 2 SINGLE ZEBRA 20 NTPS TINSUKIA AEGCL 40.0 1 SINGLE ZEBRA 21 NTPS TINSUKIA AEGCL 40.0 2 SINGLE ZEBRA 22

SALAKATI ALIPURDUAR

POWERGRID 100.

6 1 ACSR ZEBRA

23 SALAKATI

ALIPURDUAR

POWERGRID 100.

6 2 ACSR ZEBRA

24 SALAKATI BTPS AEGCL 2.7 1 ACSR ZEBRA 25 SALAKATI BTPS POWERGRID 2.7 2 ACSR ZEBRA 26

SAMAGURI JAWAHARNAGAR

AEGCL 120 1 AAAC ZEBRA

27 SAMAGURI MARIANI AEGCL

164.0

1 AAAC DEER

28 SAMAGURI MISA POWERGRID 34.4 1 ACSR ZEBRA 29 SAMAGURI MISA POWERGRID 34.4 2 ACSR ZEBRA 30

SARUSAJAI JAWAHARNAGAR

AEGCL 10 1 AAAC ZEBRA

31 SARUSAJAI LANGPI AEGCL

108.0

1 AAAC ZEBRA

32 SARUSAJAI SAMAGURI AEGCL

124.0

2 AAAC ZEBRA

33 MARIANI (PG)

MOKOKCHUNG (PG)

POWERGRID 48.8 1

ACSR ZEBRA


Page 34 of 119

34 MARIANI (PG)

MOKOKCHUNG (PG)

POWERGRID 48.8 2

ACSR ZEBRA

35 KATHALGURI

MARIANI(PG)

POWERGRID 160.5

1 ACSR TWIN MOOSE

36 KATHALGURI

MARIANI(AS)

POWERGRID 162.9

1 ACSR TWIN MOOSE

37 MISA MARIANI(PG)

POWERGRID 222.7

1 ACSR TWIN MOOSE

38 MISA MARIANI(AS)

POWERGRID 220.0

1 ACSR TWIN MOOSE

List 8:132kV Line details of Powergrid in North Eastern Region

SR. NO.

FROM TO UTILITY KM CKT

CONDUCTOR

1 AIZWAL KOLASIB POWERGRID 66.1 1 AAAC PANTHER 2 AIZWAL ZEMABAWK POWERGRID 7.0 1 ACSR PANTHER 3 BADARPUR JIRIBAM POWERGRID 67.2 1 AAAC PANTHER 4 BADARPUR KUMARGHAT POWERGRID 118.5 1 AAAC PANTHER 5 BADARPUR PANCHGRAM POWERGRID 1.0 1 AAAC PANTHER 6 BADARPUR KOLASIB POWERGRID 172.3 1 ACSR PANTHER 7 BADARPUR SILCHAR POWERGRID 19 1 ACSR PANTHER 8 BADARPUR SILCHAR POWERGRID 19 2 ACSR PANTHER 9 DIMAPUR DOYANG POWERGRID 92.5 1 ACSR PANTHER 10 DIMAPUR DOYANG POWERGRID 92.5 2 ACSR PANTHER 11 HAFLONG JIRIBAM POWERGRID 100.0 1 ACSR PANTHER

12 IMPHAL

IMPHAL (MANIPUR)

POWERGRID 1.5 1 ACSR PANTHER

13 IMPHAL DIMAPUR POWERGRID 168.9 1 ACSR PANTHER 14 JIRIBAM AIZWAL POWERGRID 170.0 1 ACSR PANTHER 15 JIRIBAM LOKTAK POWERGRID 82.4 2 ACSR PANTHER

16 UMRANSHU HAFLONG

POWERGRID/ASSAM

8.2 1 ACSR PANTHER

17 KHANDONG UMRANSHU

POWERGRID/ASSAM

11.4 1 ACSR PANTHER

18 KHANDONG KOPILI POWERGRID 10.9 1 ACSR PANTHER 19 KHANDONG KOPILI POWERGRID 10.9 2 ACSR ZEBRA 20 KHLEIHRIAT KHANDONG POWERGRID 42.5 1 ACSR PANTHER 21 KHLEIHRIAT KHANDONG POWERGRID 40.9 2 ACSR PANTHER 22 KHLEIHRIAT BADARPUR POWERGRID 76.6 1 ACSR PANTHER 23 KHLEIHRIAT KHLEIHRIAT POWERGRID 5.5 1 ACSR PANTHER


Page 35 of 119

(MeECL) 24 KUMARGHAT AIZWAL POWERGRID 131.0 1 ACSR PANTHER 25 KUMARGHAT R C NAGAR POWERGRID 104.0 1 ACSR PANTHER

26 LEKHI NIRJULI

POWERGRID, DoP,AP

4 1 ACSR PANTHER

27 LOKTAK IMPHAL POWERGRID 35.0 1 ACSR PANTHER 28 NIRJULI GOHPUR POWERGRID 42.5 1 ACSR PANTHER 29

PALLATANA SURAJMANI NAGAR

PoWERGRID

37 1 ACSR PANTHER

30 PANCHGRAM BADARPUR POWERGRID 1.0 1 AAAC PANTHER 31 R C NAGAR AGARTALA POWERGRID 8.4 1 ACSR PANTHER 32 R C NAGAR AGARTALA POWERGRID 8.4 2 ACSR PANTHER 33 RANGANADI LEKHI

POWERGRID, DoP,AP

18 3 ACSR PANTHER

34 RANGANADI ZIRO POWERGRID 44.5 1 ACSR PANTHER 35 RANGIA MOTONGA POWERGRID 49 1 ACSR PANTHER 36 SALAKATI

GELYPHU (BHUTAN)


37 SILCHAR SRIKONA POWERGRID 1 1 ACSR PANTHER 38 SILCHAR SRIKONA POWERGRID 1 2 AAAC PANTHER 39 MOKOCHUNG

(PG) MOKOKCHUNG (NAGALAND)

POWERGRID 1.4 1 ACSR Zebra

40 MOKOCHUNG (PG)

MOKOKCHUNG (NAGALAND)

POWERGRID 1.4 2 ACSR Zebra

41 BISWANATH CHARIALI (PG)

BISWANATH CHARIALI (AEGCL)


42 BISWANATH

CHARIALI (PG)

BISWANATH CHARIALI (AEGCL)


List 9: : 132kV Lines details of NEEPCO in North Eastern Region

SR. NO.

FROM TO UTILITY KM CKT CONDUCTOR

1 BALIPARA BHALUKPANG NEEPCO 35 1 ACSR PANTHER 2 BHALUKPANG KHUPI NEEPCO 32 1 ACSR PANTHER 3 KHUPI KIMI NEEPCO 8 1 ACSR PANTHER


Page 36 of 119

List 10:132kV Line details of AEGCL in North Eastern

SR. NO.

FROM TO UTILIT

Y KM CKT CONDUCTOR

1 B CHARIALI GOHPUR AEGCL 51.0 1 ACSR PANTHER 2 BALIPARA DEPOTA AEGCL 28.0 1 ACSR PANTHER 3 BALIPARA GOHPUR AEGCL 106.0 1 SINGLE ZEBRA 4 BOKAJAN DIMAPUR AEGCL 5.0 1 ACSR PANTHER 5 BORNAGAR RANGIA AEGCL 86.0 1 ACSR PANTHER 6 CTPS JAGIROAD AEGCL 35.0 1 ACSR PANTHER 7 DEPOTA B CHARIALI AEGCL 57.0 1 ACSR PANTHER 8 DEPOTA SAMAGURI AEGCL 45.0 1 ACSR PANTHER 9 DHALIGAON BTPS AEGCL 22.0 1 ACSR PANTHER 10 DHALIGAON BTPS AEGCL 22.0 2 ACSR PANTHER 11 DHALIGAON NALBARI AEGCL 106.0 1 ACSR PANTHER 12 DHALIGAON BORNAGAR AEGCL 41.0 1 ACSR PANTHER

13 DHALIGAON

ASHOK PAPER MILL

AEGCL 37.0 1 ACSR PANTHER

14 DHALIGAON BRPL AEGCL 1.0 1 ACSR PANTHER 15 DIBRUGARH MORAN AEGCL 36.0 1 ACSR PANTHER 16 DIPHU SANKARDEV NGR AEGCL 72.0 1 ACSR PANTHER 17 DISPUR CTPS AEGCL 29.0 1 ACSR PANTHER 18 GOHPUR N LAKHIMPUR AEGCL 77.0 1 ACSR PANTHER 19 GOHPUR N LAKHIMPUR AEGCL 77.0 1 ACSR PANTHER 20 GOLAGHAT BOKAJAN AEGCL 65.0 1 ACSR PANTHER 21 GOSAIGAON DHALIGAON AEGCL 65.0 1 ACSR PANTHER 22 GOSAIGAON GAURIPUR AEGCL 62.0 1 ACSR PANTHER 23 HAFLONG HAFLONG AEGCL 1.0 1 ACSR PANTHER 24 JAGIROAD HPC AEGCL 5.0 1 ACSR PANTHER 25 JIRIBAM PAILAPOOL AEGCL 15.0 1 ACSR PANTHER 26 JORHAT BOKAKHAT AEGCL 89.0 1 ACSR PANTHER 27 KAHELIPARA NARENGI AEGCL 12.0 1 ACSR PANTHER 28 KAHELIPARA SARUSAJAI AEGCL 4.0 1 ACSR PANTHER 29 KAHELIPARA SARUSAJAI AEGCL 4.0 2 ACSR PANTHER 30 KAHELIPARA SARUSAJAI AEGCL 4.0 3 ACSR PANTHER 31 KAHELIPARA SARUSAJAI AEGCL 4.0 4 ACSR PANTHER 32 KAHELIPARA DISPUR AEGCL 3.0 1 ACSR PANTHER 33 LANKA DIPHU AEGCL 71.6 1 ACSR PANTHER 34 LTPS NTPS AEGCL 60.0 1 ACSR PANTHER 35 LTPS NTPS AEGCL 60.0 2 ACSR PANTHER 36 LTPS NAZIRA AEGCL 22.0 1 ACSR PANTHER 37 LTPS NAZIRA AEGCL 22.0 2 ACSR PANTHER


Page 37 of 119

List 11: 132kV Line details of Manipur in North Eastern Region

SR. NO.

FROM TO UTILITY KM CKT

CONDUCTOR

1 CHURACHANDPUR KAKCHING MANIPUR 38.0 1 ACSR PANTHER 2 IMPHAL IMPHAL(PG) MANIPUR 2.3 2 ACSR PANTHER

38 LTPS MARIANI AEGCL 80.0 1 ACSR PANTHER 39 LTPS MORAN AEGCL 39.0 1 ACSR PANTHER 40 MARIANI JORHAT AEGCL 20.0 1 ACSR PANTHER 41 MARIANI JORHAT AEGCL 20.0 2 ACSR PANTHER 42 MARIANI GOLAGHAT AEGCL 45.0 1 ACSR PANTHER 43 MOKOKCHUNG MARIANI AEGCL 19.0 1 ACSR PANTHER 44 N LAKHIMPUR DHEMAJI AEGCL 63.0 1 ACSR PANTHER 45 NALBARI RANGIA AEGCL 22.0 1 ACSR PANTHER 46 NARENGI CTPS AEGCL 20.0 1 ACSR PANTHER 47 NAZIRA SIBSAGAR AEGCL 13.0 1 ACSR PANTHER 48 PANCHGRAM SRIKONA AEGCL 19.0 1 ACSR PANTHER 49 PANCHGRAM SILCHAR AEGCL 30.0 1 ACSR PANTHER 50 RANGIA SISUGRAM AEGCL 33.0 1 ACSR PANTHER 51 RANGIA SIPAJHAR AEGCL 38.0 1 ACSR PANTHER 52 RANGIA KAHELIPARA AEGCL 46.0 1 ACSR PANTHER 53 RANGIA ROWTA AEGCL 108.0 1 ACSR PANTHER 54 ROWTA DEPOTA AEGCL 72.0 1 ACSR PANTHER 55 ROWTA DEPOTA AEGCL 64.0 2 ACSR PANTHER 56 SAMAGURI SANKARDEV NGR AEGCL 61.0 1 ACSR PANTHER 57 SILCHAR DULLAVCHERRA AEGCL 50.0 1 ACSR PANTHER 58 SIPAJHAR ROWTA AEGCL 44.0 1 ACSR PANTHER 59 SISUGRAM KAHELIPARA AEGCL 12.0 1 ACSR PANTHER 60 SRIKONA PAILAPOOL AEGCL 35.0 1 ACSR PANTHER 61 TINSUKIA LEDO AEGCL 53.0 1 ACSR PANTHER 62 TINSUKIA DIBRUGARH AEGCL 53.0 1 ACSR PANTHER 63 TINSUKIA NTPS AEGCL 43.0 1 ACSR PANTHER 64 Silchar Halaknandi AEGCL 27.0 1 ACSR PANTHER 65 Halaknandi Dullavcherra AEGCL 34.0 1 ACSR PANTHER 66 Balipara Sonabil AEGCL 1 ACSR PANTHER 67 Bilashipara Gauripur AEGCL 38.0 1 ACSR PANTHER 68 Bilashipara kokrajhar AEGCL 24.0 1 ACSR PANTHER 69 BTPS kokrajhar AEGCL 10.0 1 ACSR PANTHER


Page 38 of 119

3 IMPHAL MANIPUR KARONG MANIPUR 60.0 1 ACSR PANTHER 4 KAKCHING KONGBA MANIPUR 45.0 1 ACSR PANTHER 5 KONGBA YAINGANGPOKPI MANIPUR 33.0 1 ACSR PANTHER 6 LOKTAK NINGTHOUKONG MANIPUR 20.0 1 ACSR PANTHER 7 LOKTAK RENGPANG MANIPUR 42.0 1 ACSR PANTHER 8 NINGTHOUKONG CHURACHANDPUR MANIPUR 23.0 1 ACSR PANTHER 9 NINGTHOUKONG CHURACHANDPUR MANIPUR 23.0 2 ACSR PANTHER 10 NINGTHOUKONG IMPHAL(PG) MANIPUR 26.2 1 ACSR PANTHER 11 RENGPANG JIRIBAM MANIPUR 40.4 1 ACSR PANTHER 12 YAINGANGPOKPI IMPHAL MANIPUR MANIPUR 42.0 1 ACSR PANTHER

List 12: 132kV Line details of TSECL in North Eastern region

SR. NO.

FROM TO UTILIT

Y KM CKT CONDUCTOR

1 AGARTALA BODHJ NGR TSECL 8.0 1 ACSR PANTHER 2 AGARTALA ROKHIA TSECL 35.0 1 ACSR PANTHER 3 AGARTALA ROKHIA TSECL 35.0 2 ACSR PANTHER 4 BARAMURA GAMAITILLA TSECL 14.0 1 ACSR PANTHER 5 BODHJ NGR JIRANIA TSECL 7.0 1 ACSR PANTHER 6 DHALABIL AGARTALA TSECL 45.0 1 ACSR PANTHER 7 GAMAITILLA AMBASA TSECL 25.0 1 ACSR PANTHER 8 JIRANIA BARAMURA TSECL 15.0 1 ACSR PANTHER 9 KAMALPUR DHALABIL TSECL 32.0 1 ACSR PANTHER 10 P K BARI KAILASHOR TSECL 18.0 1 ACSR PANTHER 11 P K BARI KUMARGHAT TSECL 1.0 1 ACSR PANTHER 12 P K BARI AMBASA TSECL 45.0 1 ACSR PANTHER 13 P K BARI KAMALPUR TSECL 31.0 1 ACSR PANTHER 14 P K BARI DHARMA NAGAR TSECL 35.0 1 ACSR PANTHER 15 PALLATANA UDAIPUR TSECL 6 1 ACSR PANTHER 16 ROKHIA UDAIPUR TSECL 40.0 1 ACSR PANTHER 17 SURAJMANINAGAR BUDHJANGNAGAR TSECL 18.3 1 ACSR PANTHER 18 SURAJMANINAGAR BUDHJANGNAGAR TSECL 18.3 2 ACSR PANTHER 19 AMBASA KAMALPUR TSECL 31 1 ACSR PANTHER 20 SONAMURA MONARCHAK TSECL 21 MONARCHAK ROKHIA TSECL 29 1 ACSR PANTHER 22 MONARCHAK UDAIPUR TSECL 41 1 ACSR PANTHER


Page 39 of 119

List 13: 132kV Line details of Nagaland in North Eastern Region

List 14: 132kV Line details of Mizoram in North eastern region

SR. NO.


1 ZUANGTUI SAITUAL MIZORAM 50.0 1 ACSR PANTHER 2 SERCHIP ZUANGTUI MIZORAM 54.0 1 ACSR PANTHER 3 LUNGLEI SERCHIP MIZORAM 69.0 1 ACSR PANTHER 4 AIZWAL LUANGMUAL MIZORAM 6.7 1 ACSR PANTHER 5 BHAIRABI KOLASIB MIZORAM 30.0 1 ACSR PANTHER

List 15: 132kV Line details of MeECL in North Eastern Region

SR. NO.


1 DIMAPUR DIMAPUR (PGCIL) NAGALAND 1 1 ACSR PANTHER 2 DIMAPUR DIMAPUR (PGCIL) NAGALAND 1 2 ACSR PANTHER 3 DOYANG MOKOKCHUNG NAGALAND 30 1 ACSR PANTHER 4 KOHIMA MELURI NAGALAND 74 1 ACSR PANTHER 5 KOHIMA DIMAPUR (PGCIL) NAGALAND 58 1 ACSR PANTHER 6 KOHIMA WOKHA NAGALAND 58 1 ACSR PANTHER 7 MELURI KIPHIRI NAGALAND 42 1 ACSR PANTHER 8 WOKHA DOYANG NAGALAND 13 1 ACSR PANTHER 9 MARIANI MOKOKCHONG NAGALAND 50 1

SR. NO.


1 AGIA NAGALBIBRA MeECL 92.0 1 ACSR PANTHER 2 EPIP I SHYAM CENTURY MeECL 0.15 1 ACSR PANTHER 3 EPIP I MAITHAN MeECL 0.2 1 ACSR PANTHER 4 EPIP I SAI PRAKASH MeECL 4.0 1 ACSR PANTHER 5 EPIP I GREYSTONE MeECL 0.7 1 ACSR PANTHER 6 EPIP II EPIP I MeECL 2.5 1 ACSR PANTHER 7 EPIP II EPIP I MeECL 2.5 2 ACSR PANTHER 8 EPIP II KILLING MeECL 10.0 1 ACSR PANTHER 9 EPIP II KILLING MeECL 10.0 2 ACSR PANTHER 10 EPIP II TRISHUL MeECL 0.2 1 ACSR PANTHER 11 EPIP II NALARI MeECL 0.2 1 ACSR PANTHER


Page 40 of 119

12 KHLEIHRIAT MeECL

LUMSHNONG MeECL 24.0 1 ACSR PANTHER

13 KHLEIHRIAT MeECL

LESHKA MeECL

26.0 1 ACSR PANTHER

14 KHLEIHRIAT MeECL

LESHKA MeECL

26.0 2 ACSR PANTHER

15 KHLEIHRIAT MeECL

KHLEIHRIAT MeECL 5.0 2 ACSR PANTHER

16 LUMSHNONG CMCL MeECL 0.16 1 ACSR PANTHER 17 LUMSHNONG MCL MeECL 3.0 1 ACSR PANTHER

18 LUMSHNONG

ADHUNIK CEMENT

MeECL 8.0 1

ACSR PANTHER

19 LUMSHNONG HILL CEMENT MeECL 8.0 1 ACSR PANTHER 20 LUMSHNONG JUD CEMENT MeECL 2.0 1 ACSR PANTHER 21 LUMSHNONG GVIL CEMENT MeECL 2.0 1 ACSR PANTHER 22 MAWLAI CHEERAPUNJI MeECL 41.0 1 ACSR PANTHER 23 MAWLAI NONGSTOIN MeECL 71.3 1 ACSR PANTHER 24 MAWLAI NEHU MeECL 9.2 1 ACSR PANTHER 25 NANGALBIBRA TURA MeECL 68.7 1 ACSR PANTHER 26 NEHU NEIGHRIMS MeECL 7.0 1 ACSR PANTHER

27 NEHU

KHLEIHRIAT MeECL

MeECL 52.6 1 ACSR PANTHER

28 NEIGHRIMS

KHLEIHRIAT MeECL

MeECL 64.8 1 ACSR PANTHER

29 NONGSTOIN NANGALBIBRA MeECL 56.0 1 ACSR PANTHER 30 UMIUM NEHU MeECL 7.0 1 ACSR PANTHER 31 UMIUM ST I UMIUM ST II MeECL 3.0 1 ACSR PANTHER 32 UMIUM ST I MAWLAI MeECL 12.0 1 ACSR PANTHER 33 UMIUM ST I UMIUM MeECL 5.0 1 ACSR PANTHER 34 UMIUM ST I MAWNGAP MeECL 33 1 ACSR PANTHER 35 UMIUM ST I MAWNGAP MeECL 33 2 ACSR PANTHER 36 UMIUM ST III UMIUM ST I MeECL 17.5 1 ACSR PANTHER 37 UMIUM ST III UMIUM ST I MeECL 17.5 2 ACSR PANTHER 38 UMIUM ST IV UMIUM ST III MeECL 8.0 1 ACSR PANTHER 39 UMIUM ST IV UMIUM ST III MeECL 8.0 2 ACSR PANTHER 40 UMTRU UMIUM ST III MeECL 41.2 1 ACSR PANTHER 41 UMTRU UMIUM ST III MeECL 41.2 2 ACSR PANTHER 42 UMTRU UMIUM ST IV MeECL 37.6 1 ACSR PANTHER 43 UMTRU UMIUM ST IV MeECL 37.6 2 ACSR PANTHER 44 UMTRU EPIP II MeECL 0.7 1 ACSR PANTHER 45 UMTRU EPIP II MeECL 0.7 2 ACSR PANTHER 46 EPIP I MEGHA CARBIDES MeECL 0.3 1 ACSR PANTHER


Page 41 of 119

List 16: 132kV Line details of AP in North eastern Region

SR. NO.


1 AGBPP DEOMALI AP 19 1 ACSR ZEBRA 2 DAPORIJO ALONG AP 81.7 1 ACSR PANTHER 3 HOZ CHIPMHU AP 30 1 ACSR PANTHER 4 LEKHI HOZ AP 18 1 ACSR PANTHER 5 ZIRO DAPORIJO AP 87.2 1 ACSR PANTHER

List 17: 66kV Line Details of North Eastern region

SR. NO.


1 AGIA LAKHIPUR AEGCL 34.0 1 ACSR WOLF 2 AMARPUR GUMTI TSECL 30.0 1 ACSR WOLF 3 BADARGHAT ROKHIA TSECL 24.0 1 ACSR WOLF 4 BADARGHAT AGARTALA TSECL 8.0 1 ACSR WOLF 5 BAGAFA SATCHAND TSECL 36.0 1 ACSR WOLF 6 BAGAFA UDAIPUR TSECL 29.0 1 ACSR WOLF 7 BARAMURA TELIAMURA TSECL 8.0 1 ACSR WOLF 8 BELONIA BAGAFA TSECL 15.0 1 ACSR WOLF 9 BOKAJAN DIPHU AEGCL 39.0 1 ACSR WOLF

10 DIMAPUR POWER HOUSE NAGALAND 4.0 1 ACSR WOLF

11 DIMAPUR SINGRIJAN NAGALAND 5.4 1 ACSR WOLF 12 DIMAPUR SINGRIJAN NAGALAND 5.4 2 ACSR WOLF 13 DULLAVCHERRA PATHARKANDI AEGCL .... 1 ACSR WOLF 14 FCI NTPS AEGCL 3.0 1 ACSR WOLF 15 FCI NTPS AEGCL 3.0 2 ACSR WOLF 16 GOKULNAGAR BADARGHAT TSECL 12.0 1 ACSR WOLF 17 GOLAGHAT BOKAJAN AEGCL 64.0 1 ACSR WOLF 18 GOLAGHAT BOKAJAN AEGCL 64.0 2 ACSR WOLF 19 GUMTI UDAIPUR TSECL 45.0 1 ACSR WOLF 20 KHIPHIRE LIKHIMRO NAGALAND 35.0 1 ACSR WOLF 21 KHIPHIRE LIKHIMRO NAGALAND 35.0 2 ACSR WOLF 22 KOLASIB VAIRENGTE MIZORAM 35.0 1 ACSR WOLF

47 MAWLAI MAWNGAP I MeECL 2 1 ACSR PANTHER


Page 42 of 119

23 MARIANI GOLAGHAT AEGCL 40.0 1 ACSR WOLF 24 MARIANI GOLAGHAT AEGCL 40.0 2 ACSR WOLF 25 MARIANI NAZIRA AEGCL 54.0 1 ACSR WOLF 26 MARIANI NAZIRA AEGCL 54.0 2 ACSR WOLF 27 MOKOKCHUNG ZUNHEBOTO NAGALAND 46.0 1 ACSR WOLF 28 MOKOKCHUNG TULI NAGALAND 56.3 1 ACSR WOLF 29 MOKOKCHUNG TUENSANG NAGALAND 50.4 1 ACSR WOLF 30 NAGINIMORA TIZIT NAGALAND 44.0 1 ACSR WOLF 31 NAZIRA NTPS AEGCL 74.0 1 ACSR WOLF 32 NAZIRA NTPS AEGCL 74.0 2 ACSR WOLF 33 NITO FARM DAIRY FARM NAGALAND 12.0 1 ACSR WOLF 34 PATHARKANDI ADAMTILLA AEGCL .... 1 ACSR WOLF 35 POWER HOUSE DAIRY FARM NAGALAND 5.0 1 ACSR WOLF 36 RABINDRA NAGAR BELONIA TSECL 38.0 1 ACSR WOLF

37 ROKHIA RABINDRA NAGAR

TSECL 23.0 1 ACSR WOLF

38 SATCHAND SABROOM TSECL 15.0 1 ACSR WOLF

39 SINGRIJAN GANESH NAGAR NAGALAND 21.4 1 ACSR WOLF

40 SINGRIJAN CHUMUKIDIMA NAGALAND 7.9 1 ACSR WOLF 41 TELIAMURA AMARPUR TSECL 35.0 1 ACSR WOLF 42 TINSUKIA RUPAI AEGCL 25.0 1 ACSR WOLF 43 TINSUKIA NTPS AEGCL 36.0 1 ACSR WOLF 44 TINSUKIA NTPS AEGCL 36.0 2 ACSR WOLF 45 TIZIT MON NAGALAND 31.0 1 ACSR WOLF 46 TUENSANG KHIPHIRE NAGALAND 55.7 1 ACSR WOLF 47 TULI NAGINIMORA NAGALAND 33.0 1 ACSR WOLF 48 UDAIPUR GOKULNAGAR TSECL 31.0 1 ACSR WOLF

List 18: Shunt Compensated Lines in North Eastern Region

SR. NO.

FROM(End 1) TO(End 2) UTILITY KM CKT End 1 End 2

1 BONGAIGAON BALIPARA POWERGRID 289.9 1 50 63 2 BONGAIGAON BALIPARA POWERGRID 289.9 2 50 63 3 BONGAIGAON BALIPARA POWERGRID 305 3 63 63 4 BONGAIGAON BALIPARA POWERGRID 305 4 63 63

5 MISA

NEW MARIANI

POWERGRID 382.9 1 50 NIL

6 MISA MARIANI POWERGRID 220 1 50 NIL 7 PALLATANA SILCHAR NETCL 247 1 63 50 8 PALLATANA SILCHAR NETCL 247 2 63 50


Page 43 of 119

9 RANGANADI

BISWANATH CHARALI

POWERGRID 204 1 50 NIL

10 RANGANADI

BISWANATH CHARALI


11 BALIPARA

BISWANATH CHARALI


12 BALIPARA

BISWANATH CHARALI


13 SILCHAR AZARA NETCL 264 1 63 63 14 BANGAIGAON AZARA NETCL 118 1 63 NIL 15 SILCHAR BYRNIHAT NETCL 217.1 1 63 63 16 BANGAIGAON BYRNIHAT NETCL 167 1 63 NIL

List 19: Shunt Compensated Inter-Regional Lines in North Eastern Region

SR. NO.

FROM(End 1) TO(End 2) UTILITY KM CKT End 1 End 2

1 BONGAIGAON BINAGURI

(ER) POWERGRID 218 1 63 NIL

2 BONGAIGAON BINAGURI

(ER) POWERGRID 218 2 63 NIL


Page 44 of 119

List 20: Inter State Line details of North Eastern Region SR. NO.

CONNECTING STATES

OWNED BY FROM TO KV KM CKTS CONDUCTOR

1 ARUNACHAL – ASSAM

POWERGRID RANGANADI BISWANTHCHARALI 400 204 D/C ACSR TWIN

MOOSE ARUNACHAL PRADESH

DEOMALI KATHALGURI 220 19.0 S/C ACSR ZEBRA

NEEPCO KHUPI BALIPARA 132 67.2 S/C ACSR PANTHER POWERGRID NIRJULI GOHPUR 132 42.5 S/C ACSR PANTHER

2 ASSAM – MEGHALAYA

POWERGRID BADARPUR KHLIEHRIET 132 76.6 S/C ACSR PANTHER POWERGRID KHANDONG KHLIEHRIET 132 42.5 D/C ACSR PANTHER AEGCL & MeECL

PANCHGRAM LUMSHNONG 132 23.4 S/C ACSR PANTHER

AEGCL & MeECL

SARASUJAI UMTRU 132 37.0 D/C ACSR PANTHER

AEGCL & MeECL

AGIA NANGALBIBRA 132 92 S/C ACSR PANTHER

POWERGRID MISA KILLING 220 115 D/C SINGLE ZEBRA AEGCL & MeECL

KAHILIPARA UMTRU 132 9.0 D/C ACSR PANTHER

3 ASSAM - NAGALAND

POWERGRID MISA DIMAPUR 220 123.5 D/C ACSR ZEBRA AEGCL & NAGALAND

MARIANI MOKOKCHUNG 132 50.0 S/C ACSR PANTHER

AEGCL BOKAJAN DIMAPUR 132 5.0 S/C ACSR PANTHER POWERGRID MARIANI MOKOKCHONG 220 48.8 D/C ACSR ZEBRA AEGCL & NAGALAND

BOKAJAN DIMAPUR 66 8.0 S/C ACSR WOLF


Page 45 of 119

ASSAM – TRIPURA

AEGCL & TRIPURA

DULLAVCHERRA DHARMANAGAR 132 29.0 S/C ACSR PANTHER

POWERGRID SILCHAR PK-BARI 400 127.2 D/C ACSR TWIN MOOSE

POWERGRID BADARPUR KUMARAGHAT 132 118.5 S/C ACSR PANTHER

4 ASSAM – MANIPUR

POWERGRID BADARPUR JIRIBAM 132 67.2 S/C ACSR PANTHER POWERGRID HAFLONG JIRIBAM 132 100.6 S/C ACSR PANTHER

POWERGRID SILCHAR IMPHAL 400 140 D/C ACSR TWIN MOOSE

AEGCL PAILAPOOL JIRIBAM 132 15.0 S/C ACSR PANTHER

5 ASSAM – MIZORAM

POWERGRID BADARPUR KOLASIB 132 107.2 S/C ACSR PANTHER

6 MIZORAM – MANIPUR

POWERGRID AIZWAL JIRIBAM 132 172.3 S/C ACSR PANTHER

7 MIZORAM – TRIPURA

POWERGRID AIZWAL KUMARAGHAT 132 131.0 S/C ACSR PANTHER

8 NAGALAND – MANIPUR

POWERGRID DIMAPUR IMPHAL 132 168.9 S/C ACSR PANTHER MANIPUR & NAGALAND

KOHIMA KARONG 132 50.0 S/C ACSR PANTHER


Page 46 of 119

List 21: Fixed, Switchable and Convertible Line reactors in North Eastern Region SR. NO

. UTILITY FROM TO

INSTALLED AT (STATION)

KV MVAR KM

CONVERTIBLE FIXE

D 1 POWERGRID BALIPARA MISA MISA 400 50 95.4 …. TRUE 2 POWERGRID BONGAIGAON BALIPARA BONGAIGAON 400 50 289.9 .... TRUE 3 POWERGRID BONGAIGAON BALIPARA BONGAIGAON 400 50 289.9 .... TRUE 4 POWERGRID BONGAIGAON BALIPARA BALIPARA 400 63 289.9 .... TRUE 5 POWERGRID BONGAIGAON BALIPARA BALIPARA 400 63 289.9 .... TRUE 6 POWERGRID BONGAIGAON BALIPARA BONGAIGAON 400 63 305.0 TRUE …. 7 POWERGRID BONGAIGAON BALIPARA BONGAIGAON 400 63 305.0 TRUE …. 8 POWERGRID BONGAIGAON BALIPARA BALIPARA 400 63 305.0 TRUE …. 9 POWERGRID BONGAIGAON BALIPARA BALIPARA 400 63 305.0 TRUE ….

10 POWERGRID BONGAIGAON BINAGURI(ER) BONGAIGAON 400 63 218.0 .... TRUE 11 POWERGRID BONGAIGAON BINAGURI(ER) BONGAIGAON 400 63 218.0 .... TRUE 12 POWERGRID MISA NEW MARIANI MISA 220 50 222.7 .... TRUE 13 POWERGRID MISA MARIANI MISA 220 50 220.0 …. TRUE 14 POWERGRID PALATANA SILCHAR SILCHAR 400 50 247 TRUE …. 15 POWERGRID PALATANA SILCHAR SILCHAR 400 50 247 TRUE …. 16 POWERGRID PALATANA SILCHAR PALLATANA 400 63 247 …. TRUE 17 POWERGRID PALATANA SILCHAR PALLATANA 400 63 247 …. TRUE

18 POWERGRID RANGANADI

BISWANATH CHARALI

RANGANADI 400 50 204 TRUE

19 POWERGRID RANGANADI

BISWANATH CHARALI

RANGANADI 400 50 204 TRUE

20 POWERGRID

BISWANATH CHARALI

BALIPARA BALIPARA 400 50 65 TRUE ....


Page 47 of 119

21 POWERGRID

BISWANATH CHARALI

BALIPARA BALIPARA 400 50 65 TRUE ....

22 POWERGRID SILCHAR BYRNIHAT SILCHAR 400 63 217.14 TRUE …. 23 POWERGRID SILCHAR BYRNIHAT BYRNIHA 400 63 217.4 TRUE …. 24 POWERGRID SILCHAR AZARA SILCHAR 400 63 264 TRUE …. 25 AEGCL SILCHAR AZARA AZARA 400 63 264 …. TRUE 26 POWERGRID BANGAIGAON BYRNIHAT BANGAIGAON 400 63 167 TRUE …. 27 POWERGRID BANGAIGAON AZARA BANGAIGAON 400 63 118 TRUE …. NOTE: CONVERTIBLE: LINE REACTORS WHICH CAN BE OPERATED UPON ONLY WHEN LINE IS IN OUT CONDITION. FIXED : LINE REACTORS WHICH ARE FIXED AND CANNOT BE OPERATED UPON AS A BUS REACTOR


Page 48 of 119

List 22: Bus Reactors in North Eastern Region

SR. NO. UTILITY INSTALLED AT

(STATION) KV

RATING STATUS

MVAR MAKE 1 POWERGRID BALIPARA 400 50 BHEL IN SERVICE 2 POWERGRID BALIPARA 400 80 BHEL IN SERVICE 3 POWERGRID BONGAIGAON 400 2 X 50 BHEL IN SERVICE 4 POWERGRID BONGAIGAON 400 2 X 80 BHEL IN SERVICE 5 POWERGRID MISA 400 50 BHEL IN SERVICE 6 POWERGRID SILCHAR 400 2 X 63 CGL IN SERVICE

7 POWERGRID BISWANATH

CHARALI 400 2 X 80 …...

IN SERVICE

8 OTPC PALATANA 400 80 BHEL IN SERVICE 9 NEEPCO RANGANADI 400 50 …. IN SERVICE 10 ASSAM MARIANI 220 2 X 12.5 .... IN SERVICE 11 ASSAM SAMAGURI 220 2 X 12.5 .... IN SERVICE 12 POWERGRID AIZWAL 132 20 .... IN SERVICE 13 POWERGRID KUMARGHAT 132 20 .... IN SERVICE 14 TRIPURA DHARMANAGAR 132 2 X 2 .... IN SERVICE 15 POWERGRID ZIRO 132 20 …. IN SERVICE 16 POWERGRID IMPHAL 132 20 …. IN SERVICE 17 POWERGRID NEW MARIANI 132 20 …. IN SERVICE 18 ASSAM SAMAGURI 132 2X12.5 …. IN SERVICE 19 ASSAM AZARA 400 63 BHEL IN SERVICE 20 MEGHALAYA BYRNIHAT 400 63 CGL IN SERVICE

List 23: Tertiary Reactors on 33kV side of 400/220/33 kV ICTs in North Eastern Region

SR. NO. UTILITY INSTALLED

AT (STATION)

INSTALLED ON

RATING STATUS MVAR MAKE

1 POWERGRID BALIPARA 33 KV SIDE

OF ICT I 4 X 25 BHEL

IN SERVICE

2 POWERGRID BONGAIGAON 33 KV SIDE


IN SERVICE

3 POWERGRID MISA 33 KV SIDE


IN SERVICE


Page 49 of 119

3 SERIES AND SHUNT CAPACITOR VOLTAGE CONTROL

3.1 Introduction 3.1.1 Capacitors aid in minimizing operating expenses and allow the utilities to serve

new loads and consumers with a minimum system investment. Series and shunt capacitors in a power system generate reactive power to improve power factor and voltage, thereby enhancing the system capacity and reducing the losses.

3.1.2 In series capacitors the reactive power is proportional to the square of the load

current, thus generating reactive power when it is most needed whereas in shunt capacitors it is proportional to the square of the voltage. Series capacitors compensation is usually applied for long transmission lines and transient stability improvement. Series compensation reduces net transmission line inductive reactance. The reactive generation I2XC compensates for the reactive consumption I2X of the transmission line. This is a self-regulating nature of series capacitors. At light loads series capacitors have little effect.

3.1.3 There are certain

unfavorable aspects of series capacitors. Generally the cost of installing series capacitors is higher than that of a corresponding installation of a shunt capacitor.

3.1.4 This is because the

protective equipment for a series capacitor is often more complicated. The factors which influence the choice between the shunt and series capacitors are summarized in Table 3.

Table 4: Equipment preference


Page 50 of 119

3.1.5 Due to various limitations in the use of series capacitors, shunt capacitors are

widely used in distribution systems. For the same voltage improvement, the rating of a shunt capacitor will be higher than that of a series capacitor. Thus a series capacitor stiffens the system, which is especially beneficial for starting large motors from an otherwise weak power system, for reducing light flicker caused by large fluctuating load, etc.

3.2 MeSeb Capacity Building And Training Document Suggest (Sub Title As Given In The PFC Document For Corporatization Of MeSeb):

3.2.1 Installation of Shunt-capacitors:

Installation of capacitors is a low cost process for reduction of technical losses. The agricultural load mainly consists of irrigation pump motors. The PF of pump motors are generally below 0.6, which means the total reactive power demand of the system is high. The reactive power demand can be reduced by installation of suitable capacitors. However, proper maintenance has to be adopted to keep the system in order. In view of the maintenance problem, reactive compensation technique could be installed at the distribution transformer centers. Care has to be taken that it does not lead to over voltage problems during the off peak hours. To avoid this there should be switch off arrangement in the capacitor bank. The optimum allocation of LT capacitors at distribution substation by minimizing a cost function, which includes loss cost in the beneficiary system and the annual cost of the capacitor bank. The reactive compensation can also be carried out at the primary distribution feeders (11 KV) lines. The optimum number, size and location of online capacitors will depend on the following factors:

• Type of load. • Quantum of load. • Load factor. • Annual load cycle. • Power factor.

3.3 As Per The Assam Gazette, Extraordinary, February 10, 2005


Page 51 of 119

IN CHAPTER 9: FREQUENCY AND VOLTAGE MANAGEMENT Sec 9.1 (d) System voltages levels can be affected by Regional operation. The SLDC shall

optimize voltage management by adjusting transformer taps to the extent available and switching of circuits/ capacitors/ reactors and other operational steps. SLDC will instruct generating stations to regulate MVAr generation within their declared parameters. SLDC shall also instruct Distribution Licensees to regulate demand, if necessary.

List 24: Substations in North Eastern Region

AGENCY 400KV 220 KV 132 KV &

66 KV TOTAL

POWER GRID

5 3 11 19

ARUNACHAL PRADESH

NIL 1 6 7

AEGCL 1 8 23 32 MANIPUR NIL NIL 7 7

MeECL 1 NIL 9 10 MIZORAM NIL NIL 6 6

NAGALAND NIL NIL 7 7 NEEPCO 1 2 4 7

NHPC NIL NIL 1 1 TSECL 1 NIL 9 10 OTPC 1 NIL NIL 1

TOTAL 9 14 82 107


Page 52 of 119

List 25: Shunt Capacitors details in North Eastern Region

SR. NO. UTILITY SUBSTATION INSTALLED

ON CAPACITY

(MVAR) 1 MeECL MAWLAI 132 KV BUS BAR 12.5 2 MeECL EPIP I 132 KV BUS BAR 20 3 MeECL EPIP II 132 KV BUS BAR 20 4 MeECL EPIP II 33 KV BUS BAR 15 5 MeECL EPIP II 33 KV BUS BAR 15 6 AEGCL BAGHJAB 33 KV BUS BAR 2X5 7 AEGCL KAHELIPARA 33 KV BUS BAR 3X5 8 AEGCL BARNAGAR 33 KV BUS BAR 2X5 9 AEGCL GOSAIGAON 33 KV BUS BAR 1X5 10 AEGCL GAURIPUR 33 KV BUS BAR 1X10 11 AEGCL RANGIA 33 KV BUS BAR 2X10 12 AEGCL MARGHERITA 33 KV BUS BAR 2X5 13 AEGCL N LAKHIMPUR 33 KV BUS BAR 1X5 14 AEGCL DULLAVCHERRA 33 KV BUS BAR 1X5 15 AEGCL DEPOTA 33 KV BUS BAR 2X5 16 AEGCL SARUSAJAI 33 KV BUS BAR 2X10 17 AEGCL ROWTA 33 KV BUS BAR 2X5 18 AEGCL DIPHU 33 KV BUS BAR 2X5 19 AEGCL DIBRUGARH 33 KV BUS BAR 2X10

20 AEGCL SHANKARDEV

NAGAR 33 KV BUS BAR 2X5

21 AEGCL RUPAI 33 KV BUS BAR 2X5 22 AEGCL SRIKONA 33 KV BUS BAR 2X5

Total Capacity of NER

273


Page 53 of 119

4 TRANSFORMER LOAD TAP CHANGER AND VOLTAGE CONTROL

4.1 Introduction 4.1.1 Transformers provide the capability to raise alternating-current generation

voltages to levels that make long-distance power transfers practical and then lowering voltages back to levels that can be distributed and used. The ratio of the number of turns in the primary to the number of turns in the secondary coil determines the ratio of the primary voltage to the secondary voltage. By tapping the primary or secondary coil at various points, the ratio between the primary and secondary voltage can be adjusted. Transformer taps can be either fixed or adjustable under load through the use of a load-tap changer (LTC). Tap capability is selected for each application during transformer design.

4.1.2 The OLTC alters the power

transformer turns ratio in a number of pre-defined steps and in that way changes the secondary side voltage.

4.1.3 Each step usually represents a

change in LV side no-load voltage of approximately 0.5-1.7%. Standard tap changers offer between ± 9 to ± 17 steps (i.e. 19 to 35 positions). The automatic voltage regulator (AVR) is designed to control a power transformer with a motor driven on-load tap-changer.

4.1.4 Typically the AVR regulates voltage at the secondary side of the power transformer. The control method is based on a step-by-step principle which means that a control pulse, one at a time, will be issued to the on-load tap-changer mechanism to move it up or down by one position.

Figure 13 Switching principle of LTC


Page 54 of 119

4.1.5 The pulse is generated by the AVR whenever the measured voltage, for a given time, deviates from the set reference value by more than the preset dead band (i.e. degree of insensitivity). Time delay is used to avoid Unnecessary operation during short voltage deviations from the pre-set value.

4.1.6 Transformer-tap changers can be used for voltage control, but the control differs

from that provided by reactive sources. Transformer taps can force voltage up (or down) on one side of a transformer, but it is at the expense of reducing (or raising) the voltage on the other side. The reactive power required to raise (or lower) voltage on a bus is forced to flow through the transformer from the bus on the other side.

4.1.7 The reactive power consumption of a transformer at rated current is within the

range 0.05 to 0.2 p.u. based on the transformer ratings. Fixed taps are useful when compensating for load growth and other long-term shifts in system use. LTCs are used for more-rapid adjustments, such as compensating for the voltage fluctuations associated with the daily load cycle. While LTCs could potentially provide rapid voltage control, their performance is normally intentionally degraded. With an LTC, tap changing is accomplished by opening and closing contacts within the transformer’s tap changing mechanism.

4.2 As Per The Assam Gazette, Extraordinary, February 10, 2005 IN CHAPTER 9: FREQUENCY AND VOLTAGE MANAGEMENT Sec 9.1(d) System voltages levels can be affected by Regional operation. The SLDC shall optimise voltage management by adjusting transformer taps to the extent available and switching of circuits/ capacitors/ reactors and other operational steps. SLDC will instruct generating stations to regulate MVAr generation within their declared parameters. SLDC shall also instruct Distribution Licensees to regulate demand, if necessary.


Page 55 of 119

List 26: ICTS details of PowerGrid in North Eastern Region

SL. NO.

SUBSTATION AGENCY ICT NO.

MVA KV

RATIO MAKE TT NT

STEP PT %AG

E KV

1 BALIPARA POWERGRID 01 315 400/220 /33 kV

TELK 17 9 1.25 5 9

1 BALIPARA POWERGRID 02 315 400/220 /33 kV

17 9 1.25 5 9

2 BONGAIGAON POWERGRID 01 315 400/220 /33 kV

TELK 17 9 1.25 5 12

3 SILCHAR POWERGRID 01 200 400/132

kV CGL 17 9 1.25 5 9B

4 SILCHAR POWERGRID 01 200 400/132

kV CGL 17 9 1.25 5 9B

5 MISA POWERGRID 01 315 400/220 /33 kV

TELK 17 9 1.25 5 05

6 MISA POWERGRID 02 315 400/220

kV CGL 17 9 1.25 5 05

7 DIMAPUR POWERGRID 01 100 220/132

kV TELK 17 9 1.25 2.75 12

8 DIMAPUR POWERGRID 02 100 220/132

kV ALSTOM 17 9 1.25 2.75 12

9 NIRJULI POWERGRID 01 50 132 /33

kV 17 9 1.25 1.65 09

10 NIRJULI POWERGRID 01 50 132 /33

kV 5 3 1.25 1.65 03

11 SALAKATI POWERGRID 01 50 220/132

kV NGEF 17 13 1.25 2.75 13

12 SALAKATI POWERGRID 02 50 220/132

kV EMCO 17 13 1.25 2.75 16

13 ZIRO POWERGRID 01 15 132 /33

kV AREVA

/ALSTOM 17 9 1.25 1.65 02

14 KOPILI POWERGRID 01 160 220/132

kV ….

17

9 1.25. 2.75 9

15 IMPHAL POWERGRID 01 50 132/33

kV

….

….

….

….

….

….

16 IMPHAL POWERGRID 02 50 132/33

kV

….

….

….

….

….

….

17 MOKOKCHUNG POWERGRID 01 30 220/132

kV …. 13 9 1.25 2.75 6


Page 56 of 119

List 27: ICTs details of NEEPCO in North Eastern Region

SL. NO.


MVA KV

RATIO MAKE TT NT

STEP PT %AGE KV

1 RHEP NEEPCO 01 7.5 132/33

KV …. …. …. …. …. 02

2 RHEP NEEPCO 02 7.5 132/33

KV …. …. …. …. …. 03

3 BALIPARA NEEPCO 01 50 220/132

KV …. 17 9 1.25 2.75 09

4 KOPILI NEEPCO 01 60 220/132

KV …. …. …. …. …. 09

5 RHEP NEEPCO 01 360 400/132

KV …. 17 9 2.5 10 9

6 RHEP NEEPCO 02 360 400/132

KV …. 17 9 2.5 10 09

List 28: ICTs details of NHPC in North Eastern Region

SL. NO.


MVA KV

RATIO MAKE TT NT

STEP PT %AGE KV

1 LOKTAK NHPC 01 5 132/33

KV …. …. …. …. …. 02

List 29: ICTs details of Arunachal Pradesh in North Eastern Region

18 MOKOKCHUNG POWERGRID 02 30 220/132

kV …. 13 9 1.25 2.75 6

19 BISWANATH

CHARIALI POWERGRID 01 200

400/132 kV

…. 17 9 1.25 5 8

20 BISWANATH

CHARIALI POWERGRID 02 200

400/132 kV

…. 17 9 1.25 5 8

SL. NO. SUBSTATION AGENCY ICT

NO. MVA KV RATIO MAKE TT NT STEP PT

%AGE KV

1 ALONG ARUNACHAL

PRADESH 01 15

132/33 KV

…. …. …. …. …. 03

2 DAPORIJO ARUNACHAL

PRADESH 01 5

132/33 KV

…. …. …. …. …. 02

3 DAPORIJO ARUNACHAL

PRADESH 02 5

132/33 KV

…. …. …. …. …. 02

4 DEOMALI ARUNACHAL

PRADESH 01 33.3

220/ 132 kV

ALSTO

…. …. …. …. 09


Page 57 of 119

List 30: ICTs details of AEGCL in North Eastern Region

SL. NO.


MVA

kV RATIO

MAKE TT NT STEP P

T %AGE KV

1 AGIA AEGCL 01 50 220/132

kV …. 23 13 1.25 2.75 12

2 AGIA AEGCL 02 100 220/132

kV …. 17 9 1.25 2.75 11

2 AGIA AEGCL 01 40 132/33

kV …. …. …. …. …. 05

3 AGIA AEGCL 01 12.5 132/33

kV …. …. …. …. …. 05

4 AZARA AEGCL 01 315 400/220 EMCO 17 9 1.25 5 08

5 AZARA AEGCL 02 315 400/220 EMCO 17 9 1.25 5 08

6 ASHOK PAPER

MILL AEGCL 01 12.5

132/33 kV

…. …. …. …. …. 05

7 ASHOK PAPER

MILL AEGCL 01 16

132/33 kV

…. …. …. …. …. 05

8 BAGHJHAP AEGCL 01 16 132/33

kV …. …. …. …. …. 05

9 BAGHJHAP AEGCL 02 16 132/33

kV …. …. …. …. …. 05

10 BALIPARA AEGCL 01 50 220 /132

kV BHEL 17 9B …. …. 9B

11 BOKO AEGCL 01 100 220/132

kV CGL 17 13 …. …. 14

12 BOKO AEGCL 02 50 220/132

kV CGL 17 13 …. …. 15

13 B CHARIALI AEGCL 01 16 132/33

kV …. …. …. …. …. 17

14 B CHARIALI AEGCL 02 16 132/33

kV …. …. …. …. …. 17

15 BORNAGAR AEGCL 01 25 132/33

kV …. …. …. …. …. ….

16 BORNAGAR AEGCL 02 25 132/33

kV …. …. …. …. …. ….

M

5 DEOMALI ARUNACHAL

PRADESH 01 16

132/33 KV

…. …. …. …. …. 04

6 LEKHI ARUNACHAL

PRADESH 01 15

132/33 KV

…. …. …. …. …. 05

7 LEKHI ARUNACHAL

PRADESH 01 20

132/33 KV

…. …. …. …. …. 05


Page 58 of 119

17 BOKAKHAT AEGCL 01 16 132/33

kV …. …. …. …. …. ….

18 BOKAKHAT AEGCL 02 16 132/33

kV …. …. …. …. …. ….

19 BOKAJAN AEGCL 01 16 132/33

kV …. …. …. …. …. ….

20 BTPS AEGCL 01 10 132/33

kV …. …. …. …. …. ….

21 BTPS AEGCL 02 10 132/33

kV …. …. …. …. …. ….

22 BTPS AEGCL 01 80 220/132

kV …. 17 9 1.25 2.75 9

23 BTPS AEGCL 02 80 220/132

kV …. 17 9 1.25 2.75 9

24 BTPS AEGCL 03 160 220/132

kV …. 17 9 1.25 2.75 9

25 CTPS AEGCL 01 16 132/33

kV …. …. …. …. …. ….

26 CTPS AEGCL 01 30 132/33

kV …. …. …. …. …. ….

27 DEPOTA AEGCL 01 31.5 132/33

kV …. …. …. …. …. 05

28 DEPOTA AEGCL 02 31.5 132/33

kV …. …. …. …. …. 05

29 DHALIGAON AEGCL 01 25 132/33

kV …. …. …. …. …. ….

30 DHALIGAON AEGCL 02 25 132/33

kV …. …. …. …. …. ….

31 DHEMAJI AEGCL 01 16 132/33

kV …. …. …. …. …. ….

32 DIPHU AEGCL 01 16 132/66

kV …. …. …. …. …. ….

33 DIPHU AEGCL 02 16 132/66

kV …. …. …. …. …. ….

34 DIBRUGARH AEGCL 01 31.5 132/33

kV …. …. …. …. …. 08

35 DIBRUGARH AEGCL 01 20 132/33

kV …. …. …. …. …. 08

36 DIBRUGARH AEGCL 02 20 132/33

kV …. …. …. …. …. 08

37 DISPUR AEGCL 01 16 132/33

kV …. …. …. …. …. ….

38 DISPUR AEGCL 02 16 132/33

kV …. …. …. …. …. ….

39 DULLAVCHERRA AEGCL 01 3.5 132/33

kV …. …. …. …. …. ….


kV …. …. …. …. …. ….

41 DULLAVCHERRA AEGCL 03 3.5 132/33 …. …. …. …. …. ….


Page 59 of 119

kV


kV …. …. …. …. …. ….


KV …. …. …. …. …. ….


KV …. …. …. …. …. ….

45 GAURIPUR AEGCL 01 10 132/33

kV …. …. …. …. …. ….

46 GAURIPUR AEGCL 02 10 132/33

KV …. …. …. …. …. ….

47 GOHPUR AEGCL 01 16 132/33

kV …. …. …. …. …. 05

48 GOHPUR AEGCL 01 10 132/33

kV …. …. …. …. …. 03

49 GOSSAIGAON AEGCL 01 16 132/33

kV …. …. …. …. …. ….

50 GOLAGHAT AEGCL 01 25 132/33

kV …. …. …. …. …. ….

51 GOLAGHAT AEGCL 02 25 132/33

kV …. …. …. …. …. ….

52 HAFLONG AEGCL 01 10 132/33

kV …. …. …. …. …. 05

53 HAFLONG AEGCL 02 10 132/33

kV …. …. …. …. …. 05

54 JORHAT AEGCL 01 25 132/33

KV …. …. …. …. …. ….

55 JORHAT AEGCL 01 16 132/33

kV …. …. …. …. …. ….

56 KAHELIPARA AEGCL 01 30 132/33

kV …. …. …. …. …. 05


kV …. …. …. …. …. 05


kV …. …. …. …. …. 06

59 KAHELIPARA AEGCL 01 10 132/33/11

kV …. …. …. …. …. 02

60 KAHELIPARA AEGCL 02 10 132/33/11

kV …. …. …. …. …. 02

61 LEDO AEGCL 01 10 132/33

kV …. …. …. …. …. 06

62 LEDO AEGCL 02 10 132/33

kV …. …. …. …. …. 06

63 LTPS AEGCL 01 7.5 132/33

kV …. …. …. …. …. ….

64 LTPS AEGCL 02 7.5 132/33

kV …. …. …. …. …. ….

65 MAJULI AEGCL 01 5.5 132/33

kV …. …. …. …. …. ….


Page 60 of 119

66 MARIANI AEGCL 01 20 132/66

kV …. …. …. …. …. 06

67 MARIANI AEGCL 02 20 132/66

kV …. …. …. …. …. 06

68 MARIANI AEGCL 01 100 220/132

kV …. 17 9 1.25 2.75 13

69 MARIANI AEGCL 02 100 220/132

kV …. 17 9 1.25 2.75 13

70 MORAN AEGCL 01 16 132/33

KV …. …. …. …. …. ….

71 MORAN AEGCL 02 16 132/33

kV …. …. …. …. …. ….

72 NALBARI AEGCL 01 16 132/33

kV …. …. …. …. …. ….

73 NALBARI AEGCL 02 16 132/33

kV …. …. …. …. …. ….

74 NALKATA (NORTH LAKHIMPUR)

AEGCL 01 10 132/33

kV …. …. …. …. …. ….

75 NALKATA (NORTH LAKHIMPUR)

AEGCL 02 10 132/33

kV …. …. …. …. …. ….

76 NARENGI AEGCL 01 25 132/33

kV …. …. …. …. …. ….

77 NARENGI AEGCL 02 25 132/33

kV …. …. …. …. …. ….

78 NAZIRA AEGCL 01 25 132/33

kV …. …. …. …. …. 06

79 NTPS AEGCL 01 25 132/66

kV …. …. …. …. …. ….

80 NTPS AEGCL 02 25 132/66

kV …. …. …. …. …. ….

81 PAILAPOOL AEGCL 01 10 132/33

kV …. …. …. …. …. 05


kV …. …. …. …. …. 05


kV …. …. …. …. …. 05

84 PANCHGRAM AEGCL 01 16 132/33

kV …. …. …. …. …. 08


kV …. …. …. …. …. 08


kV …. …. …. …. …. 01


kV …. …. …. …. …. 03

88 PAVOI AEGCL 01 16 132/33

KV …. …. …. …. …. ….

89 PAVOI AEGCL 02 16 132/33 …. …. …. …. …. ….


Page 61 of 119

KV

90 RANGIA AEGCL 01 25 132/33

KV …. …. …. …. …. 03

91 RANGIA AEGCL 02 25 132/33

KV …. …. …. …. …. 03

92 ROWTA AEGCL 01 25 132/33

KV …. …. …. …. …. 03

93 ROWTA AEGCL 02 25 132/33

KV …. …. …. …. …. 03

94 S NAGAR AEGCL 01 16 132/33

KV …. …. …. …. …. 04

95 S NAGAR AEGCL 02 16 132/33

KV …. …. …. …. …. 05

96 SAMAGURI AEGCL 01 50 220/132

kV …. 17 9 1.25 2.75 12


kV …. 17 9 1.25 2.75 12


kV …. 17 9 1.25 2.75 12


KV …. …. …. …. …. 06


KV …. …. …. …. …. 06

101 SARUSAJAI AEGCL 01 31.5 132/33

KV …. …. …. …. …. 06

102 SARUSAJAI AEGCL 02 31.5 132/33

KV …. …. …. …. …. 06

103 SARUSAJAI AEGCL 01 100 220/132

KV …. 17 9 1.25 2.75 6


kV …. 17. 9 1.25 2.75 8


kV …. 17 9 1.25 2.75 7

106 SISUGRAM AEGCL 01 31.5 132/33

KV …. …. …. …. …. 06

107 SISUGRAM AEGCL 02 31.5 132/33

KV …. …. …. …. …. 06

108 SIBSAGAR AEGCL 01 16 132/33

KV …. …. …. …. …. ….

109 SIBSAGAR AEGCL 02 16 132/33

KV …. …. …. …. …. ….

110 SIPAJHAR AEGCL 01 16 132/33

KV …. …. …. …. …. ….

111 SIPAJHAR AEGCL 02 16 132/33

KV …. …. …. …. …. ….

112 SRIKONA AEGCL 01 25 132/33

KV …. …. …. …. …. 05

113 SRIKONA AEGCL 02 25 132/33

KV …. …. …. …. …. 05


Page 62 of 119

114 TINSUKIA AEGCL 01 20 132/66

KV …. …. …. …. …. 02


KV …. …. …. …. …. 04


KV …. …. …. …. …. 03


kV …. 17 9 1.25 2.75

115


kV …. 17 9 1.25 2.75 15

119 SONABIL AEGCL

01 100 220/13

2 kV

…. …. …. …. …. …

120 SONABIL AEGCL

02 100 220/13

2 kV

…. …. …. …. …. …

121 HAILAKANDI AEGCL

01 16 132/33

KV

…. …. …. …. …. …

122 HAILAKANDI AEGCL

02 16 132/33

KV

…. …. …. …. …. …

123 SAMAGURI AEGCL

01 100 220/13

2kV …. …. …. …. …. …

124 BILASHIPARA AEGCL

01 16 132/33

KV …. …. …. …. …. …

125 BILASHIPARA AEGCL

02 16 220/13

2kV …. …. …. …. …. …

List 31: ICTs details of Manipur in North Eastern Region

SL. NO.


MVA KV

RATIO MAKE TT NT

STEP PT

%AGE KV

1 CHURACHANDPUR MANIPUR 01 20 132/33

KV …. …. …. …. …. ….

2 IMPHAL MANIPUR 01 20 132/33

KV …. …. …. …. …. ….


KV …. …. …. …. …. ….


KV …. …. …. …. …. ….

5 KAKCHING MANIPUR 01 20 132/33

KV …. …. …. …. …. ….

6 KARONG MANIPUR 01 20 132/33

KV …. …. …. …. …. ….

7 NINGTHOUKHONG MANIPUR 01 12.5 132/33

KV …. …. …. …. …. ….


Page 63 of 119

8 NINGTHOUKHONG MANIPUR 02 12.5 132/33

KV …. …. …. …. …. ….

9 YANGANGPOKPI MANIPUR 01 20 132/33

KV …. …. …. …. …. ….

10 YANGANGPOKPI MANIPUR 02 20 132/33

KV …. …. …. …. …. ….

11 JIRIBAM MANIPUR 01 6.3 132/33

KV …. …. …. …. …. ….

List 32: ICTs details of Meghalaya in North Eastern Region

SL. NO.


MVA KV

RATIO MAKE TT NT

STEP PT

%AGE KV

1 CHERAPUNJEE MeECL 01 12.5 132/33

KV …. …. …. …. …. 06

2 EPIP I MeECL 01 20 132/33

KV …. …. …. …. …. 03

3 EPIP I MeECL 02 20 132/33

KV …. …. …. …. …. 03

4 EPIP II MeECL 01 50 132/33

KV …. …. …. …. …. 08

5 KHLIEHRIAT MeECL 01 20 132/33

KV …. …. …. …. …. 05

6 KHLIEHRIAT MeECL 02 20 132/33

KV …. …. …. …. …. 06

7 MAWLAI MeECL 01 20 132/33

KV …. …. …. …. …. 04


KV …. …. …. …. …. 08


KV …. …. …. …. …. 03

10 MAWLAI MeECL 01 12.5 132/33

KV …. …. …. …. …. 07

11 NANGALBIBRA MeECL 01 10 132/33

KV …. …. …. …. …. 07

12 NANGALBIBRA MeECL 01 12.5 132/33

KV …. …. …. …. …. 06

13 NEHU MeECL 01 20 132/33

KV …. …. …. …. …. 06

14 NEHU MeECL 02 20 132/33

KV …. …. …. …. …. 06

15 NEIGRIHMS MeECL 01 10 132/33

KV …. …. …. …. …. 05

16 NEIGRIHMS MeECL 02 10 132/33

KV …. …. …. …. …. 04

17 NONGSTOIN MeECL 01 12.5 132/33

KV …. …. …. …. …. 04


Page 64 of 119

18 UMIUM ST III MeECL 01 10 132/33

KV …. …. …. …. …. 08

19 TURA MeECL 01 20 132/33

KV …. …. …. …. …. 15

20 TURA MeECL 01 15 132/33

KV …. …. …. …. …. 15

21 TURA MeECL 02 15 132/33

KV …. …. …. …. …. 15

22 TURA MeECL 03 15 132/33

KV …. …. …. …. …. 15

23 LUMSHNONG MeECL 01 10 132/33

KV …. …. …. …. …. ….

24 UMTRU MeECL 01 20 132/33

KV …. …. …. …. …. 02

25 BYRNIHAT MeECL 01 315 400/132 …. 17 9 1.25 5 9

26 BYRNIHAT MeECL 02 315 400/132 …. 17 9 1.25 5 9

27 BYRNIHAT MeECL 03 160 220/132 …. 17 9 1.25 2.75 9

28 BYRNIHAT MeECL 04 160 220/132 …. 17 9 1.25 2.75 9



List 33: ICTs details of Mizoram in North Eastern Region

SL. NO.


MVA KV

RATIO MAKE TT NT

STEP PT

%AGE KV

1 AIZAWL

LUANGMUAL MIZORAM 01 12.5

132/33 KV

…. …. …. …. …. 05

2 AIZAWL

LUANGMUAL MIZORAM 02 12.5

132/33 KV

…. …. …. …. …. 05

3 AIZAWL

ZUANGTUI MIZORAM 01 12.5

132/33 KV

…. …. …. …. …. 05

4 AIZAWL

ZUANGTUI MIZORAM 02 12.5

132/33 KV

…. …. …. …. …. 05

5 KOLASIB MIZORAM 01 12.5 132/66

KV …. …. …. …. …. 10

6 KOLASIB MIZORAM 02 12.5 132/66

KV …. …. …. …. …. 09

7 LUNGLEI MIZORAM 01 12.5 132/33

KV …. …. …. …. …. 05

8 LUNGLEI MIZORAM 02 12.5 132/33

KV …. …. …. …. …. 09

9 SERCHHIP MIZORAM 01 12.5 132/33

KV …. …. …. …. …. 02


Page 65 of 119

10 SERCHHIP MIZORAM 02 6.3 132/33

KV …. …. …. …. …. 03

11 SAITUAL MIZORAM 01 6.3 132/33

KV …. …. …. …. …. 06

List 34: ICTs details of Nagaland in North Eastern Region

SL. NO.


MVA

KV RATIO

MAKE TT NT STEP

PT %AGE KV

1 DIMAPUR NAGALAND 01 20 132/66

KV …. …. …. …. …. 05


KV …. …. …. …. …. 05


KV …. …. …. …. …. 03

4 KIPHIRE NAGALAND 01 6.5 132/66

KV …. …. …. …. …. 04


KV …. …. …. …. …. 04


KV …. …. …. …. …. 04

7 KOHIMA NAGALAND 01 8 132/33

KV …. …. …. …. …. 03


KV …. …. …. …. …. 03


KV …. …. …. …. …. 03

10 MELURI NAGALAND 01 5 132/33

KV …. …. …. …. …. 01

11 MOKOKCHUNG NAGALAND 01 12.5 132/66

KV …. …. …. …. …. 04

12 MOKOKCHUNG NAGALAND 02 12.5 132/66

KV …. …. …. …. …. 04

13 WOKHA NAGALAND 01 5 132/33

KV …. …. …. …. …. 03

List 35: ICTs details of TsECL in North Eastern Region

SL. NO.


MVA KV

RATIO MAKE TT NT

STEP PT

%AGE KV

1 AGARTALA TSECL 01 15 132/66

KV …. …. …. …. …. 09


KV …. …. …. …. …. 13


KV …. …. …. …. …. 13


Page 66 of 119


KV …. …. …. …. …. 13


KV …. …. …. …. …. 13


KV …. …. …. …. …. 13


KV …. …. …. …. …. 13


KV …. …. …. …. …. 13

9 AMBASA TSECL 01 7.5 132/33

KV …. …. …. …. …. 08

10 AMBASA TSECL 02 7.5 132/33

KV …. …. …. …. …. 08

11 BARAMURA TSECL 01 30 132/66

KV …. …. …. …. …. 05

12 DHALABIL TSECL 01 7.5 132/33

KV …. …. …. …. …. 04

13 DHARMANAGAR TSECL 01 7.5 132/33

KV …. …. …. …. …. 07


KV …. …. …. …. …. 07


KV …. …. …. …. …. 07

16 KAILASHOR TSECL 01 7.5 132/33

KV …. …. …. …. …. 08

17 KAMALPUR TSECL 01 7.5 132/11

KV …. …. …. …. …. 08

18 P K BARI TSECL 01 15 132/33

KV …. …. …. …. …. 05

19 P K BARI TSECL 01 10 132/11

KV …. …. …. …. …. 05

20 ROKHIA TSECL 01 30 132/66

KV …. …. …. …. …. 05

21 UDAIPUR TSECL 01 15 132/66

KV …. …. …. …. …. 05


KV …. …. …. …. …. 05


kV …. …. …. …. …. ….


kV …. …. …. …. …. ….


kV …. …. …. …. …. ….


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List 36: ICTs details of OTPC in North Eastern Region

SL. NO.


MVA KV

RATIO MAKE TT NT

STEP PT

%AGE KV

1 PALATANA OTPC 01 125 400/132

kV BHEL 17 9 1.25 5 9

2 PALATANA OTPC 02 125 400/132

kV 17 9 1.25 5 9

List 37: Transmission/Transformation/VAR Compensation Capacity of North Eastern Region

TRANSMISSION LINE (CKT KM)

AGENCY HVDC 400 KV 220 KV 132 KV 66 KV

POWERGRID 3458 2319 1737 2532 NIL

NEEPCO NIL NIL NIL 68 NIL NETC NIL 1328 NIL NIL NIL ENCIL NIL 444 NIL NIL NIL

STATES NIL 37 1461 5416 1492 TOTAL 3458 4091 3198 8016 1492

TRANSFORMATION CAPACITY (MVA)

POWERGRID/NEEPCO/OTPC/NHPC 3110/770/250/5 MVA

STATES 8813 MVA TOTAL 12943

REACTIVE COMPENSATION (MVAR) POWERGRID/NEEPCO/OTPC/ST

ATE 2232/100/206MVAR

STATES 346 MVAR

CAPACITIVE COMPENSATION – 273 MVAR


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5 HVDC AND VOLTAGE CONTROL

5.1 Introduction 5.1.1 Basically for transferring power over a long distance or submarine power

transmission, High voltage DC transmission lines (HVDC) are preferred which transmits power via DC (direct current). They normally consist of two converter terminals connected by a DC transmission line and in some applications, multi-terminal HVDC with interconnected DC transmission lines. Back-to-Back DC and HVDC Light are specific types of HVDC systems. HVDC Light uses new cable and converter technologies and is economical at lower power levels than traditional HVDC.

5.2 HVDC Configuration 5.2.1 Bipolar In bipolar transmission a pair of conductors is used, each at a high potential with respect to

ground, in opposite polarity. Since these conductors must be insulated for the full voltage, transmission line cost is higher than a monopole with a return conductor. However, there are a number of advantages to bipolar transmission which can make it the attractive option.

• Under normal load, negligible earth-current flows, as in the case of monopolar transmission with a metallic earth-return. This reduces earth return loss and environmental effects.

• When a fault develops in a line, with earth return electrodes installed at each end of the line, approximately half the rated power can continue to flow using the earth as a return path, operating in monopolar mode.

• Since for a given total power rating each conductor of a bipolar line carries only half the current of monopolar lines, the cost of the second conductor is reduced compared to a monopolar line of the same rating.

• In very adverse terrain, the second conductor may be carried on an independent set of transmission towers, so that some power may continue to be transmitted even if one line is damaged.


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A bipolar system may also be installed with a metallic earth return conductor. Bipolar systems may carry as much as 3,200 MW at voltages of +/-600 kV (viz., 2500 MW +/- 500 KV TALCHER – KOLAR HVDC link in INDIA connecting NEW GRID to SR GRID ) Submarine cable installations initially commissioned as a monopole may be upgraded with additional cables and operated as a bipole.

5.2.2 Back to back

A back-to-back station (or B2B for short) is a plant in which both static inverters and rectifiers are in the same area, usually in the same building. The length of the direct current line is kept as short as possible. HVDC back-to-back stations are used for

• Coupling of electricity mains of different frequency (as in INDIA; the interconnection between NEW GRID and SR GRID through 1000 MW HVDC BHADRAVATI and 1000 MW HVDC GAZUWAKA)

• Coupling two networks of the same nominal frequency but no fixed phase relationship (viz., HVDC SASARAM, HVDC VINDHYACHAL).

• Different frequency and phase number (for example, as a replacement for traction current converter plants)

The DC voltage in the intermediate circuit can be selected freely at HVDC back-to-back stations because of the short conductor length. The DC voltage is as low as possible, in order to build a small valve hall and to avoid series connections of valves. For this reason at HVDC back-to-back stations valves with the highest available current rating are used.

5.2.3 A high voltage direct current (HVDC) link consists of a rectifier and an inverter. The rectifier side of the HVDC link is equivalent to a load consuming positive real and reactive power and the inverter side of the HVDC link as a generator providing positive real power and negative reactive power (i.e. absorbing positive reactive power).

5.2.4 Thermistor based HVDC converters always consume reactive power when in

operation. A DC line itself does not require reactive power and voltage drop on the line is only the IR drop where I is the DC current. The converters at the both ends of the line, however, draw reactive power from the AC system. The reactive power consumption of the HVDC converter/inverter is 50-60 % of the active power converted. It is independent of the length of the line.

http://en.wikipedia.org/wiki/Traction_current_converter_plant


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5.2.5 The reactive power requirements of the converter and system have to be met by

providing appropriate reactive power in the station. For those reason reactive power compensations devices are used together with reactive power control from the ac side in the form of filter and capacitor banks.

5.2.6 Both AC and DC harmonics are generated in HVDC converters. AC harmonics are

injected into the AC system and DC harmonics are injected into the DC line. These harmonics have the following harmful effects:

• Interference in communication system. • Extra power losses in machines and capacitors connected in the

system. • Some harmonics may produce resonance in AC circuits resulting in

over voltages. • Instability of converter controls.

Figure 14 HVDC Fundamental components


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5.2.7 Harmonics are normally minimized by using filters. The following types of filters are used:

• AC filters. • DC filters. • High frequency filters.

AC Filters AC filters are RLC circuits connected between phase and earth. They offer low impedance to harmonic frequencies. Thus, AC harmonic currents are passed to earth. Both tuned and damped filter arrangements are used. The AC harmonic filters also provide reactive power required for satisfactory operation of converters and also partly injects reactive power into the system.

DC Filters DC filters are similar to AC filters. A DC filter is connected between pole bus and neutral bus. It diverts DC harmonics to earth and prevents them from entering DC lines. Such a filter does not supply reactive power as DC line does not require reactive power.

HIGH FREQUENCY FILTERS HVDC converters may produce electrical noise in the carrier frequency band from 20 Khz to 490 Khz. They also generate radio interference noise in the mega hertz range of frequencies. High frequency (PLC-RI) filters are used to minimize noise and interference with PLCC. Such filters are connected between the converter transformer and the station AC bus.

5.3 Reactive Power Source Reactive power is required for satisfactory operation of converters and also to boost the AC side voltages. AC harmonic filters which help in minimizing harmonics also provide reactive power partly. Additional supply may be obtained from shunt (switched) capacitor banks usually installed in AC side.

5.4 ±800 kV HVDC Bi-Pole HVDC Biswanath Charali-Alipurduar-Agra is first Multi –terminal HVDC india with terminals located at Biswanath Charali (NER), Agra(NR) and Alipurduar(ER) and operating at +/- 800kV. This HVDC was planned in around 2006 to evacuate generation from NER, Sikkim and Bhutan to load centres in NR and WR. This is the first HVDC designed to evacuate power from large hydro


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projects of NER and ER region. Considering the seasonality of hydro generation this is the first HVDC bipole having flows in either direction depending upon the season and providing flexibility and function as a pseudo phase-shifter. The capacity of each terminal at Biswanath Charali(NER) & Alipurduar (ER) is of 3000 MW.There are two terminals at Agra with capacity of 3000MW each. After commissioning of this HVDC it has provided first interconnection between NER and NR and additional interconnection between ER & NR. Presently only one (1500MW) HVDC interconnection between NER & NR is commissioned with metallic return.

5.5 Technical details of Biswanath Chariali –Alipurduar-Agra HVDC:

The Schematic Diagram of HVDC BNC-Agra is as follow. The technical details of the line are as follows:

a. Transmission Line

a. Voltage : +/-800 kV DC b. Length : 1726 km c. Conductor Type : Lapwing-Hexa bundled d. Resistance in Ohms (Approx.) : ~12.310

Figure 15: Schematic Diagram of HVDC-BNC


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b. Converter Transformers

a. Agra: 4 converter transformers each with capacity of 6*295.1 MVA

b. BNC: 2 converter transformers each with capacity of 6*295.1 MVA

c. Filter Banks a. At Agra end (Total 3705 MVAR)

b. At BNC end (Total1983 MVAR)

S.NO Filter Bank(Z1

Capacity(MVAR)

Filter Bank(Z2

Capacity(MVAR)

Filter Bank(Z3

Capacity(MVAR)

Filter Bank(Z4

Capacity(MVAR)

Filter Bank(Z5

Capacity(MVAR)

1 Hp12 125 Hp12 125 Hp12 125 Hp12 125 Hp3 125

2 Hp12b 201 Hp12b 201 Hp12

b 201 Hp12b 201 Hp12

b 201

3 Shunt capacit

or 200 Hp24

/36 b 200 Shunt capacitor

200 Hp24/36 b 200 Hp24

/36 200

4 Shunt Capaci

tor 200

Shunt Capac

itor 200

Shunt Capac

itor 200

Shunt Capac

itor 200

Shunt Capac

itor 200

Table 5: AC Filter Bank at HVDC Agra

S.NO Filter Bank(Z1

Capacity(MVAR)

Filter Bank(Z2

Capacity(MVAR)

Filter Bank(Z3 Capacity(MVAR)

1 HP12 125 HP12 125 HP12 125

2 HP12B 160 HP12B 160 HP12B 160

3 HP24/36 125 Hp24/36 125 HP24/36 125

4 HP3 159 HP24/36 125 HP3 159

5 Shunt Capacitor 155 Shunt

Capacitor 155

Table 6: AC Filter Bank at HVDC BNC.


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5.6 Impact of Largest Filter Switching Under Different HVDC Power Order.

HVDC Power Order

Voltage at BNC before Switching of Filter

Bank

Voltage at BNC after Switching of Filter

Bank Rise in Voltage

0 417.6 440.6 23

500 426.2 453.8 27.6

1000 403.4 426.4 23

Table 7: Impact of Largest Filter Switching under different HVDC Power order.

Reactive power requirement of Converter transformer varies continuously depending upon the power order. Reactive power generated by Switching of filters are in blocks so at each set point there may be excess/deficit of reactive power resulting exchange of reactive power with the grid causing bus voltage to change. Depending upon voltage to be increased or decreased set point may be decided accordingly.


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6 FACTS AND VOLTAGE CONTROL

6.1 Introduction 6.1.1 The demands of lower power losses, faster response to system parameter change,

and higher stability of system have stimulated the development of the Flexible AC Transmission systems (FACTS). Based on the success of research in power electronics switching devices and advanced control technology, FACTS has become the technology of choice in voltage control, reactive/active power flow control, transient and steady-state stabilization that improves the operation and functionality of existing power transmission and distribution system.

6.1.2 The achievement of these studies enlarge the efficiency of the existing generator

units, reduce the overall generation capacity and fuel consumption, and minimize the operation cost. The power electronics-based switches in the functional blocks of FACTS can usually be operated repeatedly and the switching time is a portion of a periodic cycle, which is much shorter than the conventional mechanical switches.

6.1.3 The advance of semiconductors increases the switching frequency and voltage-

ampere ratings of the solid switches and facilitates the applications. For example, the switching frequencies of Insulated Gate Bipolar Transistors (IGBTs) are from 3 kHz to 10 kHz which is several hundred times the utility frequency of power system (50~60Hz). Gate turn-off thyristors (GTOs) have a switching frequency lower than 1 kHz, but the voltage and current rating can reach 5-8 kV and 6 kA respectively.

6.2 Static Var Compensator (SVC) 6.2.1 Static Var Compensator is “a shunt-connected static Var generator or absorber

whose output is adjusted to exchange capacitive or inductive current so as to maintain or control specific parameters of the electrical power system (typically bus voltage)” .SVC is based on thyristors without gate turn-off capability.

6.2.2 The operating principal and characteristics of thyristors realize SVC variable

reactive impedance. SVC includes two main components and their combination: (1) Thyristor-controlled and Thyristor-switched Reactor (TCR and TSR); and (2) Thyristor-switched capacitor (TSC). Figure 15 shows the diagram of SVC.


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6.2.3 TCR and TSR are both composed of a shunt-connected reactor controlled by two

parallel, reverse-connected thyristors. TCR is controlled with proper firing angle input to operate in a continuous manner, while TSR is controlled without firing angle control which results in a step change in reactance.

6.2.4 TSC shares similar composition

and same operational mode as TSR, but the reactor is replaced by a capacitor. The reactance can only be either fully connected or fully disconnected zero due to the characteristic of capacitor. With different combinations of TCR/TSR, TSC and fixed capacitors, a SVC can meet various requirements to absorb/supply reactive power from/to the transmission line.

6.3 Converter-based Compensator

6.3.1 Static Synchronous Compensator (STATCOM) is one of the key Converter-based Compensators which are usually based on the voltage source inverter (VSI) or current source inverter (CSI), as shown in Figure 16 (a). Unlike SVC, STATCOM controls the output current independently of the AC system voltage, while the DC side voltage is automatically maintained to serve as a voltage source. Mostly, STATCOM is designed based on the VSI (VOLTAGE SOURCE INVERTER).

Figure 17 STATCOM topologies: (a) STATCOM based on VSI and CSI (b) STATCOM with storage

Figure 16 Static VAR Compensators (SVC): TCR/TSR, TSC, FC and

Mechanically Switched Resistor


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6.3.2 Compared with SVC, the topology of a STATCOM is more complicated. The

switching device of a VSI is usually a gate turn-off device paralleled by a reverse diode; this function endows the VSI advanced controllability.

6.3.3 Various combinations of the switching devices and appropriate topology make it

possible for a STATCOM to vary the AC output voltage in both magnitude and phase. Also, the combination of STATCOM with a different storage device or power source (as shown in Figure 16b) endows the STATCOM the ability to control the real power output.

6.3.4 STATCOM has much better dynamic performance than conventional reactive

power compensators like SVC. The gate turn-off ability shortens the dynamic response time from several utility period cycles to a portion of a period cycle. STATCOM is also much faster in improving the transient response than a SVC. This advantage also brings higher reliability and larger operating range.

6.4 Series-connected controllers

6.4.1 As shunt-connected controllers, series- connected FACTS controllers can also be divided into either impedance type or converter type.

6.4.2 The former includes Thyristor-

Switched Series Capacitor (TSSC), Thyristor-Controlled Series Capacitor (TCSC), Thyristor- Switched Series Reactor, and Thyristor-Controlled Series Reactor.

6.4.3 The latter, based on VSI, is usually

in the Compensator (SSSC). The composition and operation of different types are similar to the operation of the shunt connected peers. Figure shows the diagrams

of various series-connected controllers.

Figure 18 Series-connected FACTS controllers: (a) TCSR and TSSR; (b) TSSC; (c) SSSC


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7 GENERATOR REACTIVE POWER AND VOLTAGE CONTROL

7.1 Introduction 7.1.2 An electric-power generator’s primary function is to convert fuel (or other energy

resource) into electric power. Almost all generators also have considerable control over their terminal voltage and reactive-power output.

7.1.3 The ability of a generator to

provide reactive support depends on its real-power production which is represented in the form of generator capability curve or D - curve. Figure 18 shows the combined limits on real and reactive production for a typical generator. Like most electric equipment, generators are limited by their current-carrying capability. Near rated voltage, this capability becomes an MVA limit for the armature of the generator rather than a MW limitation, shown as the armature heating limit in the Figure.

7.1.4 Production of reactive power involves increasing the magnetic field to raise the

generator’s terminal voltage. Increasing the magnetic field requires increasing the current in the rotating field winding. This too is current limited, resulting in the field-heating limit shown in the figure. Absorption of reactive power is limited by the magnetic-flux pattern in the stator, which results in excessive heating of the stator-end iron, the core-end heating limit. The synchronizing torque is also reduced when absorbing large amounts of reactive power, which can also limit

Figure 19 D-Curve of a typical Generator


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generator capability to reduce the chance of losing synchronism with the system.

7.1.5 The generator prime mover (e.g., the steam turbine) is usually designed with less capacity than the electric generator, resulting in the prime-mover limit in Fig. 18. The designers recognize that the generator will be producing reactive power and supporting system voltage most of the time. Providing a prime mover capable of delivering all the mechanical power the generator can convert to electricity when it is neither producing nor absorbing reactive power would result in underutilization of the prime mover.

7.1.6 To produce or absorb additional VARs beyond these limits would require a

reduction in the real-power output of the unit. Capacitors supply reactive power and have leading power factors, while inductors consume reactive power and have lagging power factors. The convention for generators is the reverse. When the generator is supplying reactive power, it has a lagging power factor and its mode of operation is referred to as overexcited. When a generator consumes reactive power, it has a leading power factor region and is under excited.

7.1.7 Control over the reactive output and the terminal voltage of the generator is

provided by adjusting the DC current in the generator’s rotating field. Control can be automatic, continuous, and fast. The inherent characteristics of the generator help maintain system voltage.

7.1.8 At any given field setting, the generator has a specific terminal voltage it is

attempting to hold. If the system voltage declines, the generator will inject reactive power into the power system, tending to raise system voltage. If the system voltage rises, the reactive output of the generator will drop, and ultimately reactive power will flow into the generator, tending to lower system voltage.

7.1.9 The voltage regulator will accentuate this behavior by driving the field current in

the appropriate direction to obtain the desired system voltage. Because most of the reactive limits are thermal limits associated with large pieces of equipment, significant short-term extra reactive-power capability usually exists. Power-system stabilizers also control generator field current and reactive-power output in response to oscillations on the power system. This function is a part of the network-stability ancillary service.


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7.2 Synchronous Condensers

7.2.1 Every synchronous machine (motor or generator) has the reactive power capability. Synchronous motors are occasionally used to provide voltage support to the power system as they provide mechanical power to their load. Some combustion turbines and hydro units are designed to allow the generator to operate without its mechanical power source simply to provide the reactive-power capability to the power system when the real power generation is unavailable or not needed.

7.2.2 Synchronous machines that are designed exclusively to provide reactive support

are called synchronous condensers. Synchronous condensers have all of the response speed and controllability advantages of generators without the need to construct the rest of the power plant (e.g., fuel-handling equipment and boilers). Because they are rotating machines with moving parts and auxiliary systems, they may require significantly more maintenance than static alternatives. They also consume real power equal to about 3% of the machine’s reactive-power rating. That is, a 50-MVAR synchronous condenser requires about 1.5 MW of real power.

7.2.3 As per planning philosophy and general guidelines in the Manual on

Transmission planning criteria issued by CEA (MOP, India), Thermal / Nuclear Generating Units shall normally not run at leading power factor. However for the purpose of charging unit may be allowed to operate at leading power factor as per the respective capability curve.

7.2.4 Generator capability may depend significantly on the type and amount of cooling.

This is particularly true of hydrogen cooled generators where cooling gas pressure affects both the real and reactive power capability

SL. NO. STATION UTILITY UNIT NO. UNIT

CAPACITY (MW)

TYPE

1 KOPILI HEP NEEPCO 1,2,3 & 4* 50 HYDEL

2 RANGANADI HEP NEEPCO 1,2 & 3 135 HYDEL

Table 8: List of units in NER required to be normally operated with free Governor action and AVR in service.

*Units running in 132 KV pocket is exempt from FGMO.


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Capability Curve 1: LTPS unit 5, 6, 7


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Capability Curve 2: NTPS UNIT 1, 2 & 3


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Capability Curve 3: NTPS UNIT 4


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Capability Curve 4: NTPS UNIT 6


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Capability Curve 5: LTPS


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Capability Curve 6: NTPS


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Capability Curve 7: UMIUM ST I


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Capability Curve 8: UMIUM STAGE II


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Capability Curve 9: UMIUM STAGE III


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Capability Curve 10: UMIUM STAGE IV


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Capability Curve 11: AGBPP UNIT 5, 6, 7, 8 & 9


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Capability Curve 12: AGBPP UNIT 1, 2, 3 & 4


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Capability Curve 13: AGTPP


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Capability Curve 14: DOYANG HEP UNIT 1


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Capability Curve 15: KHANDONG HEP UNIT 2


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Capability Curve 16: KOPILI HEP UNIT 1


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Capability Curve 17: KOPILI HEP UNIT 2


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Capability Curve 18: KOPILI HEP ST II


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Capability Curve 19: RANGANADI HEP


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Capability Curve 20: LOKTAK HEP


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Capability Curve 21: ROKHIA UNIT 3, 4 & 6


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Capability Curve 22: ROKHIA & BARAMURA


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Capability Curve 23: OTPC PALATANA GTG


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Capability Curve 24: OTPC PALATANA STG


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Capabilty Curve 25:BgTPP


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8 CONCLUSION 8.1 Generators, synchronous condensers, SVCs, and STATCOMs all provide fast,

continuously controllable reactive support and voltage control. LTC transformers provide nearly continuous voltage control but they are slow because the transformer moves reactive power from one bus to another, the control gained at one bus is at the expense of the other. Capacitors and inductors are not variable and offer control only in large steps.

8.2 An unfortunate characteristic of capacitors and capacitor-based SVCs is that

output drops dramatically when voltage is low and support is needed most. The output of a capacitor, and the capacity of an SVC, is proportional to the square of the terminal voltage. STATCOMs provide more support under low-voltage conditions than capacitors or SVCs do because they are current-limited devices and their output drops linearly with voltage.

8.3 The output of rotating machinery (i.e., generators and synchronous condensers)

rises with dropping voltage unless the field current is actively reduced. Generators and synchronous condensers generally have additional emergency capacity that can be used for a limited time. Voltage-control characteristics favour the use of generators and synchronous condensers. Costs, on the other hand, favor capacitors.

8.4 Generators have extremely high capital costs because they are designed to

produce real power, not reactive power. Even the incremental cost of obtaining reactive support from generators is high, although it is difficult to unambiguously separate reactive-power costs from real-power costs. Operating costs for generators are high as well because they involve real-power losses. Finally, because generators have other uses, they experience opportunity costs when called upon to simultaneously provide high levels of both reactive and real power.

8.5 Synchronous condensers have the same costs as generators but, because they are

built solely to provide reactive support, their capital costs do not include the prime mover or the balance of plant and they incur no opportunity costs. SVCs and STATCOMs are high-cost devices, as well, although their operating costs are lower than those for synchronous condensers and generators.


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9 SUMMARY 9.1 The process of controlling voltages and managing reactive power on

interconnected transmission systems is well understood from a technical perspective. Three objectives dominate reactive-power management. First, maintain adequate voltages throughout the transmission system under current and contingency conditions. Second, minimize congestion of real-power flows. Third, minimize real-power losses.

9.2 This process must be performed centrally because it requires a comprehensive

view of the power system to assure that control is coordinated. System operators and planners use sophisticated computer models to design and operate the power system reliably and economically. Central control by rule works well but may not be the most technically and economically effective means.

9.3 The economic impact of control actions can be quite different in a

restructured/regulated industry than for vertically integrated utilities. While it may be sufficient to measure only the response of the system in aggregate for a vertically integrated utility, determining individual generator performance will be critical in a competitive environment.

9.4 While it reduces or eliminates opportunity costs by providing sufficient capacity,

it can waste capital. When an investor is considering construction of new generation, the amount of reactive capability that the generator can provide without curtailing real-power production should depend on system requirements and the economics of alternatives, not on a fixed rule.

9.5 The introduction of advanced devices, such as STATCOMs and SVCs, further

complicates the split between transmission- and generation based voltage control. The fast response of these devices often allows them to substitute for generation-based voltage control. But their high capital costs limit their use. If these devices could participate in a competitive voltage-control market, efficient investment would be encouraged.

9.6 In areas with high concentrations of generation, sufficient interaction among

generators is likely to allow operation of a competitive market. In other locations, introduction of a small amount of controllable reactive support on the transmission system might enable market provision of the bulk of the reactive support. In other locations, existing generation would be able to exercise market power and would continue to require economic regulation for this service.


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9.7 A determination of the extent of each type within each region would be a useful

contribution to restructuring. System planners and operators need to work closely together during the design of new facilities and modification of existing facilities. Planners must design adequate reactive support into the system to provide satisfactory voltage profiles during normal and contingency operating conditions. Of particular importance is sufficient dynamic support, such as the reactive output of generators, which can supply additional reactive power during contingencies.

9.8 System operators must have sufficient metering and analytical tools to be able to

tell when and if the operational reactive resources are sufficient. Operators must remain cognizant of any equipment outages or problems that could reduce the system’s static or dynamic reactive support below desirable levels. Ensuring that sufficient reactive resources are available in the grid to control voltages may be increasingly difficult because of the disintegration of the electricity industry.

9.9 Traditional vertically integrated utilities contained, within the same entity,

generator reactive resources, transmission reactive resources, and the control center that determined what resources were needed when. Presently, these resources and functions are placed within three different entities. In addition, these entities have different, perhaps conflicting, goals. In particular, the owners of generating resources will be driven, in competitive generation markets, to maximize the earnings from their resources. They will not be willing to sacrifice revenues from the sale of real power to produce reactive power unless appropriately compensated.

9.10 Similarly, transmission owners will want to be sure that any costs they incur to

expand the reactive capabilities on their system (e.g., additional capacitors) will be reflected fully in the transmission rates that they are allowed to charge.

9.11 Failure to appropriately compensate those entities that provide voltage-control

services could lead to serious reliability problems and severe constraints on inter regional links and other congested areas as TTC (Total Transfer Capability) has a voltage limit function as a baggage with it which is directly linked to var compensation. With dynamic ATC’s (Available Transfer capability), Var compensation if not seriously thought of may have serious commercial implications in time to come due to the amount of bulk power trading happening across the country in today’s context.


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10 STATUTORY PROVISIONS FOR REACTIVE POWER MANAGEMENT AND VOLTAGE CONTROL

10.1 Provision in the Central Electricity Authority (Technical Standard for connectivity to the grid) Regulations 2007 [8]:

Extracts from this standard is as reproduced below for ready reference.

Part II: Grid Connectivity Standards applicable to the Generating Units The units at a generating station proposed to be connected to the grid shall comply with the following requirements besides the general connectivity conditions given in the regulations and general requirements given in part-I of the Schedule:-

1. New Generating Units Hydro generating units having rated capacity of 50 MW and above shall be capable of operation in synchronous condenser mode, where ever feasible

2. Existing Units

For thermal generating unit having rated capacity of 200 MW and above and hydro Units having rated capacity of 100 MW and above, the following facilities would be provided at the time of renovation and modernization.

(1) Every generating unit shall have Automatic Voltage Regulator. Generators having rated capacity of 100 MW and above shall have Automatic Voltage Regulator with two separate with two separate channels having independent inputs and automatic changeover.

10.2 Provision in The Indian Electricity Grid Code (IEGC), 2010:

2.1 As per sec 3.5 of IEGC planning criterion general policy

(a) The planning criterion are based on the security philosophy on which the ISTS has been planned. The security philosophy may be as per the Transmission Planning Criteria and other guidelines as given by CEA. The general policy shall be as detailed below:

a) As a general rule, the ISTS shall be capable of withstanding and be secured against the following contingency outages

a. without necessitating load shedding or rescheduling of generation during Steady

State Operation:


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-Outage of a 132 kV D/C line or, -Outage of a 220 kV D/C line or, -Outage of a 400 kV S/C line or, -Outage of single Interconnecting Transformer, Or -Outage of one pole of HVDC Bipole line, or one pole of HVDC back to back Station or

-Outage of 765 kV S/C line.

b. without necessitating load shedding but could be with rescheduling of generation during steady state operation-

- Outage of a 400 kV S/C line with TCSC, or - Outage of a 400kV D/C line, or - Outage of both pole of HVDC Bipole line or both poles of HVDC back to back Station or

- Outage of a 765kV S/C line with series compensation.

ii) The above contingencies shall be considered assuming a pre-contingency system depletion (Planned outage) of another 220 kV D/C line or 400 kV S/C line in another corridor and not emanating from the same substation. The planning study would assume that all the Generating Units may operate within their reactive capability curves and the network voltage profile shall also be maintained within voltage limits specified

(e) CTU shall carry out planning studies for Reactive Power compensation of ISTS

including reactive power compensation requirement at the generator’s /bulk consumer’s switchyard and for connectivity of new generator/ bulk consumer to the ISTS in accordance with Central Electricity Regulatory Commission ( Grant of Connectivity, Long-term Access and Medium-term Open Access in inter-state Transmission and related matters) Regulations, 2009.

10.2.2 As per Sec 4.6.1 of IEGC, Important Technical Requirements for

Connectivity to the Grid: Reactive Power Compensation

a) Reactive Power compensation and/or other facilities, shall be provided by STUs, and Users connected to ISTS as far as possible in the low voltage systems close to the load points thereby avoiding the need for exchange of Reactive Power to/from ISTS and to maintain ISTS voltage within the specified range.

b) The person already connected to the grid shall also provide additional reactive

compensation as per the quantum and time frame decided by respective RPC in consultation with RLDC. The Users and STUs shall provide information to RPC and RLDC regarding the installation and healthiness of the reactive compensation equipment on regular basis.


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RPC shall regularly monitor the status in this regard.

10.2.3 In chapter 5 of IEGC operating code for regional grids:

5.2(k) All generating units shall normally have their automatic voltage regulators (AVRs) in operation. In particular, if a generating unit of over fifty (50) MW size is required to be operated without its AVR in service, the RLDC shall be immediately intimated about the reason and duration, and its permission obtained. Power System Stabilizers (PSS) in AVRs of generating units (wherever provided), shall be got properly tuned by the respective generating unit owner as per a plan prepared for the purpose by the CTU/RPC from time to time. CTU /RPC will be allowed to carry out checking of PSS and further tuning it, wherever considered necessary.

5.2(o) All Users, STU/SLDC , CTU/RLDC and NLDC, shall also facilitate identification,

installation and commissioning of System Protection Schemes (SPS) (including inter-tripping and run-back) in the power system to operate the transmission system closer to their limits and to protect against situations such as voltage collapse and cascade tripping, tripping of important corridors/flow-gates etc.. Such schemes would be finalized by the concerned RPC forum, and shall always be kept in service. If any SPS is to be taken out of service, permission of RLDC shall be obtained indicating reason and duration of anticipated outage from service.

5.2(s All Users, RLDC, SLDC STUs , CTU and NLDC shall take all possible measures to ensure that the grid voltage always remains within the following operating range.

Voltage – (KV rms)

Nominal Maximum Minimum

765 800 728

400 420 380

220 245 198

132 145 122

110 121 99

66 72 60

33 36 30


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Table 9: IEGC operating voltage range

5.2(u) (ii) During the wind generator start-up, the wind generator shall ensure that the

reactive power drawl (inrush currents in case of induction generators) shall not affect the grid performance.

10.2.4 In chapter 6 of IEGC Section-6.6 Reactive Power & Voltage Control:

1. Reactive power compensation should ideally be provided locally, by generating

reactive power as close to the reactive power consumption as possible. The Regional Entities except Generating Stations are therefore expected to provide local VAr compensation/generation such that they do not draw VArs from the EHV grid, particularly under low-voltage condition. To discourage VAr drawals by Regional Entities except Generating Stations, VAr exchanges with ISTS shall be priced as follows:

- The Regional Entity except Generating Stations pays for VAr drawal when voltage

at the metering point is below 97% - The Regional Entity except Generating Stations gets paid for VAr return when

voltage is below 97% - The Regional Entity except Generating Stations gets paid for VAr drawal when

voltage is above103%

The Regional Entity except Generating Stations pays for VAr return when voltage is above 103% Provided that there shall be no charge/payment for VAr drawal/return by a regional Entity except Generating Stations on its own line emanating directly from an ISGS.

2. The charge for VArh shall be at the rate of 10 paise/kVArh w.e.f. 1.4.2010, and this will

be applicable between the Regional Entity, except Generating Stations, and the regional pool account for VAr interchanges. This rate shall be escalated at 0.5paise/kVArh per year thereafter, unless otherwise revised by the Commission.


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3 Notwithstanding the above, RLDC may direct a Regional Entity except Generating Stations to curtail its VAr drawal/injection in case the security of grid or safety of any equipment is endangered.

4. In general, the Regional Entities except Generating Stations shall endeavor to

minimize the VAr drawal at an interchange point when the voltage at that point is below 95% of rated, and shall not return VAr when the voltage is above 105%. ICT taps at the respective drawal points may be changed to control the VAr interchange as per a Regional Entity except Generating Stations’s request to the RLDC, but only at reasonable intervals.

5. Switching in/out of all 400 kV bus and line Reactors throughout the grid shall be

carried out as per instructions of RLDC. Tap changing on all 400/220 kV ICTs shall also be done as per RLDCs instructions only.

6. The ISGS and other generating stations connected to regional grid shall

generate/absorb reactive power as per instructions of RLDC, within capability limits of the respective generating units, that is without sacrificing on the active generation required at that time. No payments shall be made to the generating companies for such VAr generation/absorption.

7. VAr exchange directly between two Regional Entities except Generating Stations on

the interconnecting lines owned by them (singly or jointly) generally address or cause a local voltage problem, and generally do not have an impact on the voltage profile of the regional grid. Accordingly, the management/control and commercial handling of the VAr exchanges on such lines shall be as per following provisions, on case-by-case basis: i) The two concerned Regional Entities except Generating Stations may mutually

agree not to have any charge/payment for VAr exchanges between them on an interconnecting line.

ii) The two concerned Regional Entities except Generating Stations may mutually

agree to adopt a payment rate/scheme for VAr exchanges between them identical to or at variance from that specified by CERC for VAr exchanges with ISTS. If the agreed scheme requires any additional metering, the same shall be arranged by the concerned Beneficiaries.

iii) In case of a disagreement between the concerned Regional Entities except

Generating Stations (e.g. one party wanting to have the charge/payment for VAr exchanges, and the other party refusing to have the scheme), the scheme as specified in Annexure-2 shall be applied. The per kVArh rate shall be as specified by CERC for VAr exchanges with ISTS.


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iv) The computation and payments for such VAr exchanges shall be effected as mutually agreed between the two Beneficiaries.

10.3 The AEGCL Gazette, Extraordinary, February 10, 2005

10.3.1 IN CHAPTER 9: FREQUENCY AND VOLTAGE MANAGEMENT

10.3.1.1 (9.1) Introduction

(a) This section describes the method by which all Users of the State Grid shall cooperate with SLDC in contributing towards effective control of the system frequency and managing the grid voltage.

(b) State Grid normally operates in synchronism with the North-Eastern Regional Grid

and NERLDC has the overall responsibility of the integrated operation of the North-Eastern Regional Power System. The constituents of the Region are required to follow the instructions of NERLDC for the backing down generation, regulating loads, MVAR drawal etc. to maintain the system frequency and the grid voltage.

(c) SLDC shall instruct SSGS to regulate Generation/Export and hold reserves of active

and reactive power within their respective declared parameters. SLDC shall also regulate the load as may be necessary to meet the objective.

(d) System voltages levels can be affected by Regional operation. The SLDC shall

optimise voltage management by adjusting transformer taps to the extent available and switching of circuits/ capacitors/ reactors and other operational steps. SLDC will instruct generating stations to regulate MVAr generation within their declared parameters. SLDC shall also instruct Distribution Licensees to regulate demand, if necessary.

10.3.1.2 (9.2) Objective The objectives of this section are as follows:

(a) To define the responsibilities of all Users in contributing to frequency and voltage management.

(b) To define the actions required to enable SLDC to maintain System voltages

and frequency within acceptable levels in accordance Planning and Security Standards of IEGC.


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10.3.1.3 (9.3) Frequency Management

The rated frequency of the system shall be 50 Hz and shall normally be regulated within the limits prescribed in IEGC Clause 4.6(b). As a constituent of North-Eastern Region, the SLDC shall make all possible efforts to ensure that grid frequency remain within normal band of 49.5 – 50.2Hz (Presently IEGC band is 49.7-50.2 Hz).

10.3.1.4 (9.4) Basic philosophy of control Frequency being essentially the index of load-generation balance conditions of the system, matching of available generation with load, is the only option for maintaining frequency within the desired limits. Basically, two situations arise, viz., a surplus situation and a deficit situation. The automatic mechanisms available for adjustment of load/generation are (i) Free governor action; (ii) Maintenance of spinning reserves and (iii) Under-frequency relay actuated shedding. These measures are essential elements of system security. SLDC shall ensure that Users of the State Grid comply with provisions of clause 6.2 of the IEGC so far as they apply to them. The SLDC in coordination with Users shall exercise the manual mechanism for frequency control under following situations:

10.3.1.5 (9.5) Falling frequency:

Under falling frequency conditions, SLDC shall take appropriate action to issue instructions, in coordination with NERLDC to arrest the falling frequency and restore it to be within permissible range. Such instructions may include dispatch instruction to SSGS and/or instruction to Distribution Licensees and Open access customers to reduce load demand by appropriate manual and/or automatic load shedding.

10.3.1.6 (9.6) Rising Frequency

Under rising frequency conditions, SLDC shall take appropriate action to issue instructions to SSGS in co-ordination with NERLDC, to arrest the rising frequency and restore frequency within permissible range through backing down hydel generation and thermal generation to the level not requiring oil support. SLDC shall also issue instructions to Distribution Licensees and Open access customers in coordination with NERLDC to lift Load shedding (if exists) in order to take additional load.


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10.3.1.7 (9.7) Responsibilities SLDC shall monitor actual Drawal against scheduled Drawal and regulate internal generation/demand to maintain this schedule. SLDC shall also monitor reactive power drawal and availability of capacitor banks. Generating Stations within AEGCL shall follow the dispatch instructions issued by SLDC.Distribution Licensees and Open access customers shall co-operate with SLDC in managing load & reactive power drawal on instruction from SLDC as required.

10.3.1.8 (9.8) Voltage Management

(a) Users using the Intra State transmission system shall make all possible efforts to ensure that the grid voltage always remains within the limits specified in IEGC at clause 6.2(q) and produced below:

(b) AEGCL Gridco and/or SLDC shall carry out load flow studies based on operational

data from time to time to predict where voltage problems may be encountered and to identify appropriate measures to ensure that voltages remain within the defined limits. On the basis of these studies SLDC shall instruct SSGS to maintain specified voltage level at interconnecting points. SLDC and AEGCL Gridco shall co-ordinate with the Distribution Licensees to determine voltage level at the interconnection points. SLDC shall continuously monitor 400/220/132kV voltage levels at strategic sub-stations to control System voltages.

(c) SLDC in close coordination with NERLDC shall take appropriate measures to control

System voltages which may include but not be limited to transformer tap changing, capacitor / reactor switching including capacitor switching by Distribution Licensees at 33 kV substations, operation of Hydro unit as synchronous condenser and use of MVAr reserves with SSGS within technical limits agreed to between AEGCL Gridco and Generators. Generators shall inform SLDC of their reactive reserve capability promptly on request.

Nominal Maximum Minimum

400 420 380

220 245 198

132 145 122


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(d) APGCL and IPPs shall make available to SLDC the up to date capability curves for all Generating Units, as detailed in Chapter 5.indicating any restrictions, to allow accurate system studies and effective operation of the Intra State transmission system. CPPs shall similarly furnish the net reactive capability that will be available for Export to / Import from Intra State transmission system.

(e) Distribution Licensees and Open access customers shall participate in voltage

management by providing Local VAR compensation (as far as possible in low voltage system close to load points) such that they do not depend upon EHV grid for reactive support.

10.3.1.9 (9.9) General

Close co-ordination between Users and SLDC, AEGCL Gridco and NERLDC shall exist at all times for the purposes of effective frequency and voltage management.


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11. BIBLIOGRAPHY:

1. Best practice manual of transformer for BEE and IREDA by Devki energy consultancy pvt. ltd.

2. NERPC progress report August, 2010. 3. Document on MeSEB capacity building and training document 4. Manual on Transmission Planning Criteria, CEA, Govt. of India, June 1994 5. Indian Electricity Grid Code, CERC, India, 2010 with Amendment. 6. The Central Electricity Authority (Technical Standard for connectivity to

the grid) Regulations 2007. 7. Operation procedure for NER July 2016. 8. Document on Metering code for AEGCL grid. 9. Principles of efficient and reliable reactive power supply and

consumption, staff report, FERC, Docket No. AD05-1-000, February 4, 2005

10. Proceedings of workshop on grid security & management 28th and 29th April, 2008 Bangalore.

11. Extra High Voltage AC transmission Engineering – R D Begamudre. 12. Electrical Engineering Handbook – SIEMENS. 13. C. W. Taylor, “Power System Voltage Stability”, McGraw-Hill, 1994. 14. THE AEGCL GAZETTE, EXTRAORDINARY, FEBRUARY 10, 2005

North Eastern Regional Load Despatch Centre

Shillong

Power System operation Corporation Limited (A wholly own Subsidiary of PowerGrid)

Dongtieh-Lower Nongrah –Lapalang

Shillong-793006

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