Project Report - Subham Saini (New)

7/22/2019 Project Report - Subham Saini (New)

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A

SUMMERTRAININGPROJECTREPORT

ON

765/400/220KVTRAMSMISSIONSUB-STATION

OF

POWERGRIDCORPORATIONOFINDIALIMITED

MEERUT, UTTARPRADESH

SUBMITTEDBY:

SHUBHAMSAINI

B.TECH,3RD YEAR

IIMTENGINEERINGCOLLEGE

MEERUT


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PREFACE

It is a matter of great pleasure for me to present the following report on

my INDUSTRIAL INPLANT TRAINING at POWERGRID

CORPORATION OF INDIA LIMITED, MEERUT, otherwise one

seldom gets a chance to go through any industry after on the job training

/ placement. It outlines the course of project work during my training in

a specific & oriented manner over a period of one month B.Tech., 6th

Semester, Electrical Engineering.

I am grateful to Sh. Y. P. Singh (Chief Manager, S/S)

for his valuable guidance and support, without which it was not possible

to understand the subject theoretically as well as practically in such a

short time. I am also thankful to Sh. R. K. Agarwal, Dy.Manager, S/S,

Sh. A. K. Saxena, Sh. K. K. Purwar for their continuous friendly

support without which the completion of this report would have been a

thought only.

( SHUBHAM SAINI )


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ACKNOWLEDGEMENT

We cannot achieve anything worthwhile in the field of technical educationunless or until the theoretical education acquired in the classroom is effectively

wedded to its practical approach that is taking place in the modern industries

and research institutes. It gives me a great pleasure to have an opportunity to

acknowledge and to express gratitude to those who were associated with my

training at POWERGRID.


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CONTENTS

PARTICULARS PAGE NO

COMPANY PROFILE 5

MEERUT SUBSTATION DETAILS 6

SINGLE LINE DIAGRAM OF

MEERUT SUBSTATION

7

TECHNICAL DETAILS OF

MEERUT SUBSTATION

8

SPECIALITIES OF MEERUTSUBSTATION 9

INTRODUCTION TO BAY

EQUIPMENTS

10

REACTIVE POWER

COMPENSATION OFTRANSMISSION LINES

14


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COMPANY PROFILE

Power Grid Corporation of India Limited (POWERGRID),is an Indian

Central TransmissionUtility(A Navratna Company) headquartered at Gurgaon,India. Power Grid wheels about 51% of the total power generated in India on itstransmission network. Power Grid has a pan India presence with around 95,330

Circuit-km of Transmission network and 156 nos. of EHVAC & HVDC sub-stations with a total transformation capacity of 91,945 MVA. The Inter-regional

capacity is enhanced to 28000 MW. Power Grid has also diversified into Telecombusiness and established a telecom network of more than 25,000 km across the

country. Power Grid has consistently maintained the transmission system

availability over 99.90% which is at par with the International Utilities.

In 1980 the Rajadhyaksha Committee on Power Sector Reforms submitted its

report to the Government of India suggesting extensive reforms in the Indianpower sector. Based on the recommendations of the Rajadhyaksha Committee, in1981 the Government of India took the policy decision to form a national power

grid which would pave the way for the integrated operation of the central andregional transmission systems. Pursuant to this decision to form a national power

grid, PowerGrid was incorporated on October 23, 1989 under the companies Act,1956 as the National Power Transmission Corporation Limited (NPTC), with the

responsibility of planning, executing, owning, operating and maintaining the highvoltage transmission systems in the country. The Company received a certificate

for commencement of business on November 8, 1990. Subsequently, the name ofthe Company was changed to Power Grid Corporation of India Limited

(POWERGRID) with effect from October 23, 1992.

POWERGRID has enhanced the inter-regional capacity of National Grid to 28,000

MW.India is divided into 5 Regions - Northern Region(NR), Eastern Region(ER),Western Region(WR), Southern Region(SR) and North-East Region(NER). Out of

all these Regions the NR,ER,WR and NER are synchronized which is known asNEW Grid. Whereas SR is not synchronized with the rest of the regions with AC

lines and hence runs on a slightly different Frequency. SR is connected with WR

and ER with HVDC links only. When PGCIL was formed then the responsibilityof Regional Load Dispatch Centres(RLDCs) was handed over to POWERGRID by

Central Electricity Authority(CEA). On 25th February,2009 the National Load

Dispatch Center(NLDC) was inaugurated. Now these Regional LoadDispatchCentres(RLDCs) and National Load Dispatch Center(NLDC) is a separate

organisation named POSOCO (Power system Operation Corporation), a whollyowned subsidiary of POWERGRID.
http://en.wikipedia.org/wiki/Electric_utilitieshttp://en.wikipedia.org/wiki/Electric_utilitieshttp://www.nldc.in/http://www.nldc.in/http://en.wikipedia.org/wiki/Power_System_Operation_Corporation_Limitedhttp://en.wikipedia.org/wiki/Power_System_Operation_Corporation_Limitedhttp://www.nldc.in/http://www.nldc.in/http://en.wikipedia.org/wiki/Electric_utilities


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MEERUT SUB-STATION DETAILS

765/400/220 KV Meerut substation was conceptualized for evacuation of power

generated from Tehri hydro electric power project (8x250 MW) from Tehri and

(4x100 MW) from koteshwar. The 2400 MW power generated by THDC has to betransferred to northern grid through Meerut substation. To accompalish this task,

POWERGRID has constructed 02 nos. single circuit 765 KV transmission lines

from Tehri to Meerut, For onward feeding of power evacuated from TEHRI

HYDRO ELECTRIC POWER PROJECT to NORTHERN GRID through

connections in Uttar Pradesh Power Corporaion (UPPCL) 220 KV substations.

Meerut substation is connected to 400/220 KV Mandola substation of

POWERGRID by one 400 KV double circuit Meerut-Mandola line. Also it is

connected to 400 KV Muzaffarnagar substation of UPPCL by one single circuit

400 KV Meerut-Muzaffarnagar line. All these interconnections are constructed

under the head GANGA VALLEY TRANSMISSION PROJECT(G.V.T.P).

Meerut S/S connected to Kaithal S/S by one 400KV D/C Low impedance Line of

high capacity in the year of 2010.

Further, in the year of 2012-13, the capacity of Meerut S/s has enhanced by adding

400KV, one D/C Bareilly & one D/C Mandola Lines after LILO of Bareilly-

Mandola Line at Meerut.

In the year of 2013, the Meerut S/S is upgraded to 765KV Sub-Station by adding /

commissioning of 2x1500MW 765/400KV ICTs, one 240MVAR 765KV Bus

Reactor & one 765KV S/C Meerut- Agra Line alongwith one 240MVAR, 765KV

Line Reactor.

765KV Meerut- Bhiwani Line is under advance stage of construction and will be

commissioned shortly.


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SINGLE LINE DIAGRAM OF MEERUT SUB-STATION


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TECHNICAL DETAILS OF MEERUT SUB-STATION

Total Transformation Capacity : 945 MVAfor 400/200 kV

3000 MVAfor 765/400 kV

Nos. of Transmission Lines : 765 KV : 01 Nos.

400 KV : 11 Nos.

220 KV : 07 Nos.

Nos. of Bays : 765 KV : 10 Nos.

400 KV : 28 Nos.

220 KV : 12 Nos.

Nos. of ICTs : 07 Nos, 1 Phase, 500 MVA each,

765/400/33 KV, OFAF, BTW China Make

03 Nos., 3 Phase, 315 MVA each,

400/220/33 KV OFAF Type BHEL Make.

Nos. of Reactors : 08 Nos, 1 Phase, 80 MVAR each,

765 KV, TBEA China Make

02 Nos. 3 Phase, 420 KV, 50 MVAR each,

BHEL Make

Bus Bar Scheme : 765 KV : One & Half Breaker Scheme.

400 KV : One & Half Breaker Scheme.

220 KV : Two Main & Transfer Bus Scheme

FSC : 02 Nos, 50%, 765KV on Koteshwar Lines


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SPECIALITIES OF MEERUT SUB-STATION

1. A, 400KV D/C Low Impedance line is constructed between Kaithal and Meerut.

This line is characterized by increased spacing between the bundled conductors

which results in less flux linkages and hence, less impedance.

2. Worlds second and Indias first FIXED SERIES COMPENSATION (FSC) for

765 KV LINES is done in this Sub-station. FSC results in the increased capacity of

lines to carry more power.

At present, Meerut Sub-station is having three Nos. 3 Phase, 315 MVA,400/220

KV Auto Transformers with provisions of one No. future Transformerof 500MVA

which will be installed in 2013-14 F.Yr. Both 765KV Meerut-Tehri single circuit1

& 2 are charged at 400KV, although both single circuits are designed &

constructed for 765 KV level.1000MW Power generation at Tehri Hydro Electric

Project has already started through Unit No. 1, 2, 3 and 4 and generated power is

transmitted from Tehri to Meerut Substation through 400 KV Meerut - Tehri

Circuit 1 & 2 via 400KV GIS at Koteshwar S/S. GIS Koteshwar S/S is also

connected to Koteshwar HEP of 400MW Generation capacity.


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INTRODUCTION TO BAY EQUIPMENTS

CURRENT TRANSFORMER (CT) : Current Transformer is similar in

construction to single phase power transformer and obeys the same fundamental

laws but primary current of CT is not controlled by the connected load insecondary circuit, in fact it is governed by the current in the main circuit viz.

line/transformer to which it is connected. A typical 400/220KV CT has five cores

which are used for following functions:

Core 1-Busbar 1 protection

Core 2-Busbar 2 protection

Core 3-Metering

Core 4-Main 1 Protection


Knee-point voltage is that sinusoidal voltage of rated frequency applied to

secondary winding of CT which when increased by 10% causes the exciting

current to increase by 50%. Metering core of CT is required to maintain its

accuracy up to 150% of the rated primary current and it is desirable that this core

gets saturated beyond this current to prevent damage of the connected meters.

Protection core of CT is required to maintain its accuracy at fault current level

which is very high compared to rated current. As such this core is not required to

maintain accuracy at normal line/ICT currents. However this core must not saturate

up to maximum short circuit level of the station which is 40 kA for 400/220 KV

substation otherwise this will cause mal operation of the protection schemes

employed.

CAPACITIVE VOLTAGE TRANSFORMER (CVT) : It is used for providing

small representative voltage of Primary system for metering and protection

applications.CVT consists of coupling capacitors, intermediate voltage

transformer, high frequency coupling terminal. The HF terminal is used for PLCC

purpose. The CVT has three cores which are utilized as follows:


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Core 3-Metering

CIRCUIT BREAKER (CB) : It is major substation equipment which is used to

control(switch on/switch off) the line / transformer/reactor. It is ON LOAD device,

which can isolate the circuit in normal/ fault condition manually / automatically

through protection system. It can carry rated line / transformer current

continuously and can easily handle tripping operation during heavy fault currents.

Now-a-days SF6 type CB is used in 765/400/220 KV systems.

POWER TRANSFORMER (INTER CONNECTING TRANSFORMER,

ICT) : This is the costliest equipment of substation. ICT is used to step down the

EHV transmission voltage(400 KV) to HV transmission voltage (220 KV).

Normally 315 MVA, OFAF type auto transformer having 2 secondary windings is

being used. The first secondary winding provides 220 KV voltage and the other 33

KV voltage (Tertiary winding). Usually tertiary winding is connected in closed

delta formation and can be used for auxiliary station supply purpose. In practice, it

is preferred to install three phase ICT as far as possible, however in case of hilly

terrain where due to transportation limitations, three single phase ICT units are

installed.

REACTOR : It is similar to transformer in appearance and used for absorbing

the reactive power from the system when system voltage is high. It has air core, oil

filled, ONAN type. Generally 50 & 63 MVAR shunt reactors are used with

line/bus. Both switchable and non switchable type shunt reactors are in use.


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ISOLATOR : It is a OFF load switch to disconnect the circuit visibly. This can

be operated only when associated CB and earth switch is in open condition.

Normally horizontal centre break type isolator is used.

LIGHTINING/ SURGE ARRESTER : It provides protection against high

voltage switching/lightning surges, which can enter in substation and can damage

the costly equipments.

POWER LINE CARRIER COMMUNICATION

Power line communication (PLC) is a system for carrying data on a conductor that

is also used for electric power transmission. It is also known as power linecarrier, power line digital subscriber line (PDSL), mains communication, power

line telecom(PLT), power line networking (PLN), and broadband over powerlines (BPL),

Utility companies use special coupling capacitors to connect radio transmitters to

the power-frequency AC conductors. Frequencies used are in the range of 24 to500 kHz, with transmitter power levels up to hundreds of watts. These signals may

be impressed on one conductor, on two conductors or on all three conductors of a

high-voltage AC transmission line. Several PLC channels may be coupled onto one

HV line. Filtering devices are applied at substations to prevent the carrierfrequency current from being bypassed through the station apparatus and to ensure

that distant faults do not affect the isolated segments of the PLC system. Thesecircuits are used for control of switchgear, and for protection of transmission lines.

For example, a protective relay can use a PLC channel to trip a line if a fault is

detected between its two terminals, but to leave the line in operation if the fault iselsewhere on the system. Power line carrier communication (PLCC) is mainly used

for telecommunication, tele-protection and tele-monitoring between electrical

substations through power lines at high voltages, such as 110 kV, 220 kV, 400

kV. The major benefit is the union of two applications in a single system, which isparticularly useful for monitoring electric equipment and advanced energymanagement techniques

To sectionalize the transmission network and protect against failures, a "wave trap"is connected in series with the power (transmission) line. They consist of one or

more sections of resonant circuits, which block the high frequency carrier waves(24 kHz to 500 kHz) and let power frequency current (50 Hz - 60 Hz) pass


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through. Wave traps are used in switchyard of most power stations to prevent

carrier from entering the station equipment. Each wave trap has a lightning arresterto protect it from surge voltages.

A coupling capacitor is used to connect the transmitters and receivers to the high

voltage line. This provides low impedance path for carrier energy to HV line butblocks the power frequency circuit by being a high impedance path. The couplingcapacitor may be part of a capacitor voltage transformer used for voltage

measurement.

L ine trap

It is also called wave trap. It is connected in series with the power (transmission)

line. It blocks the high frequency carrier waves (24 KHz to 500 KHz) and let

power waves (50Hz-60Hz) to pass through. It is basically an inductor of rating in

0.5 or 01milli Henry.

L ine matching unit

LMU is a composite unit consisting of Drain Coil, Isolation transformer with

Lightning Arrester on its both the sides, a tuning device and an earth switch.

Tuning device is the combination of R-L-C circuits which act as filter circuit.

LMU is also known as coupling device. Together with coupling capacitor, LMU

serves the purpose of connecting effectively the audio/ radio frequency signals to

either transmission line or PLC terminal and protection of the PLCC unit from the

over voltages caused due to transients on power system.


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REACTIVE POWER COMPENSATION OF TRANSMISSION

LINES:

GENERAL INTRODUCTION :

During the past two decades, the increase in electrical energy demand haspresented higher requirements from the power industry. More power plants,

substations, and transmission lines need to be constructed. However, the mostcommonly used devices in present power grid are the mechanically-controlled

circuit breakers. The long switchingperiods and discrete operation make them difficult to handle the frequently

changed loads smoothly and damp out the transient oscillations quickly. In order tocompensate these drawbacks, large operational margins and redundancies are

maintained to protect the system from dynamic variation and recover from faults.

This not only increases the cost and lowers the efficiency, but also increases thecomplexity of the system and augments the difficulty of operation and control.Severe black-outs happened recently in power grids worldwide and these have

revealed that conventional transmission systems are unable to manage the controlrequirements of the complicated interconnections and variable power flow.

Therefore, investment is necessary for the studies into the security and stability of

the power grid, as well as the improved control schemes of the transmission

system.Different approaches such as reactive power compensation and phase shifting have

been applied to increase the stability and the security of the power systems. Thedemands 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 hasbecome the technology of choice in voltage control, reactive/active power flowcontrol, transient and steady-state stabilization that improves the operation and

functionality of existing power transmission and distribution system . 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.


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SHUNT COMPANSATION

Shunt compensation, especially shunt reactive compensation has been widely used

in transmission system to regulate the voltage magnitude, improve the voltage

quality, and enhance the system stability. Shunt-connected reactors are used toreduce the line over-voltages by consuming the reactive power, while shunt-

connected capacitors are used to maintain the voltage levels by compensating thereactive power to transmission line.

SERIES COMPENSATION

Series compensation aims to directly control the overall series line impedance of

the transmission line. the AC power transmission is primarily limited by the series

reactive impedance of the transmission line. A series-connected can add a voltage

in opposition to the transmission line voltage drop, therefore reducing the seriesline impedance.


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FLEXIBLE AC TRANSMISSION SYSTEM (FACTS)

The history of FACTS controllers can be traced back to 1970s when Hingoranipresented the idea of power electronic applications in power system compensation.

From then on, various researches were conducted on the application of high powersemiconductors in transmission systems. The shunt-connected Static VAR

compensator (SVC) using solid-state switches and the series-connected controllers


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were proposed in AC transmission system application. In 1988, Hingorani defined

the FACTS concept and described the wide prospects of the application.Nowadays, FACTS technology has shown strong potential. Many examples of

FACTS devices and controllers are in operation

As presented in , FACTS and FACTS controllers are defined in IEEE Terms andDefinitions as:

Flexible AC Transmission System (FACTS): Alternating current transmission

systems incorporating power electronic-based and other static controllers toenhance controllability and increase power transfer capability.

FACTS CONTROLLER: A power electronic-based system and other staticequipment that provide control of one or more AC transmission system parameters.

As new technology for power transmission system, FACTS and FACTS controllers

not only provide the same benefits as conventional compensators withmechanically-controlled switches in steady state but also improve the dynamic andtransient performance of the power system. 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 theconventional mechanical switches.

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 frequencylower than 1 kHz, but the voltage and current rating can reach 5-8 kV and 6 kA

respectively.

FACTS controllers have many configurations. In general, they can be categorized

into shunt-connected controllers, series-connected controllers and their

combinations.


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SHUNT-CONNECTED CONTROLLERS

FACTS controllers can be impedance type, based on thyristors without gate turn-

off capability, which are called Static Var Compensator (SVC) for shunt-connected

application. Another type of FACTS controllers is converter-based which is

usually in the form of a Static Synchronous Compensator (STATCOM).

STATIC VAR COMPENSATOR (SVC)

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


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maintain or control specific parameters of the electrical power system (typically

bus voltage).SVC is based on thyristors without gate turn-off capability. The operating principal

and characteristics of thyristors realize SVC variable reactive impedance. SVC

includes two main components and their combination: (1) Thyristor-controlled andThyristor-switched Reactor (TCR and TSR); and (2) Thyristor-switched capacitor

(TSC).

TCR and TSR are both composed of a shunt-connected reactor controlled by twoparallel, 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.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 differentcombinations of TCR/TSR, TSC and fixed capacitors, a SVC can meet variousrequirements to absorb/supply reactive power from/to the transmission line.

CONVERTER-BASED COMPENSATOR

Static Synchronous Compensator (STATCOM) is one of the key Converter-basedCompensators which are usually based on the voltage source inverter (VSI) or

current source inverter (CSI Unlike SVC, STATCOM controls the output current

independently of the AC system voltage, while the DC side voltage isautomatically maintained to serve as a voltage source. Mostly, STATCOM is

designed based on the VSI.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. Various

combinations of the switching devices and appropriate topology make it possiblefor 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 endows the STATCOM the ability to control the real power output.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.


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SERIES-CONNECTED CONTROLLERS

As shunt-connected controllers, series-connected FACTS controllers can also be

divided into either impedance type or converter type. The former includesThyristor-Switched Series Capacitor (TSSC), Thyristor-Controlled Series

Capacitor (TCSC), Thyristor-Switched Series Reactor, and Thyristor-ControlledSeries Reactor. The latter, based on VSI, is usually in the form of a Static

Synchronous Series Compensator (SSSC). The composition and operation ofdifferent types are similar to the operation of the shunt-connected peers.

STATIC SYNCHRONOUS COMPENSATOR (STATCOM)

As discussed in the previous section, STATCOM is a very popular FACTScontroller application effective in transmission system voltage control. Since 1980when the first STATCOM (rated at 20 Mvar) using force-commutated thyristor

inverters was put into operation in Japan,many examples have been installed and

the ratings have been increased considerably. In 1991, KEPCO and MitsubishMotors installed a 80MVar TATCOM at Inuyama Switching Station. In 1996,

TVA,EPRI and Westinghouse installed a 100MVar STATCOM at Sullivan 500

kV Substation. In 2001, EPRI and Siemens developed a 200MVar STATCOM atMarcy 345kV substation. It is expected that more STATCOMs will be installed

due to the advances in technology and commercial success.

STATCOM could have many topologies, but in most practical applications itemploys the DC to AC converter, which can also be called a Voltage Source

Inverter (VSI) in 3-phase configuration as the primary block. The basic theory ofVSI is to produce a set of controllable 3-phase output voltages/ currents at the

fundamental frequency of the AC bus voltage from a DC input voltage source such

as a charged capacitor or a DC energy supply device. By varying the magnitude

and phase angle of the output voltage and current, the system can exchangeactive/reactive power between the DC and AC buses, and regulate the AC bus

voltage.


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CONCLUSION

On the whole my training at POWERGRID, 765/400/220KV,

MEERUT-S/S was very useful experience which has obviously made

a tremendous impact on my quest for further knowledge in the field

of Electrical Engineering. It has given me a better understanding and

exposure to some of the operational and practical problems that engineers

have to grapple in the designing, Installation, Operation & Maintenance of

POWER SYSTEM. The pleasant working atmosphere and helpful nature of

POWERGRIDIANS made staying there and working a memorable

experience.

( Shubham Saini )

B.Tech, 3rd Year

IIMT ENGINEERING COLLEGE

MEERUT

Project Report - Subham Saini (New)

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