Application of FACTS in Indian Power System

Subrata Mukhopadhyay, Senior Member, IEEE, Ashok K. Tripathy, Senior Member, IEEE, V.K.Prasher, and Krishan K . Arya

Abstract-- Flexible AC Transmission System or in short FACTS is a technology-based solution envisioned to help the utilities deal with changes in the power delivery business. Its

role in enhancing the transfer capability of existing transmission system under steady state as well as improving system security

under dynamic contingencies has ushered in a new era. Inspired with the success of such ventures necessitated due to the right- of-way and other problems elsewhere in the world, in India a project has been undertaken on a 400 kV line between Kanpur (Uttar Pradesh) and Ballabhgarh (Haryana) in the Northern Grid. It has a 27% fixed and an 8% variable capacitor section. The latter can be raised to 20% through thyristor control. Power carrying capacity is envisaged to be increased from 400

to 600 MW.

The present paper gives details of project, planning studies, design parameters and project performance.

Zndex Terms- FACTS, HVDC, power electronics, reactive power, stability, thyristor, varistor

I. INTRODUCTION

Today, the electric industry faces awesome challenges: asset

utilization, requirement for transmission network.

Transmission constraints impact both economic interchange

and system stability. Construction of new transmission line

has become more difficult and expensive, with permitting and

Subrata Mukhopadhyay and Krishan K. Arya are with Central Electricity

Authority, Sewa Bhavan, R.K.Puram, New Delhi - 110066, INDIA (e-mail:

subrata(idieee.org, kkarya-2001 @rediffmail.cQrn)

Ashok K. Tripathy is with Bharat Heavy Electricals Ltd., Integrated Office

Complex, Lodhi Road, New Delhi - 110003, INDIA (e-mail:

trioathy~bhelindustrv.com)

V.K.Prasher is with PowerGrid Corporation of India Ltd., B-9 Qutab

Institutional Area, Katwaria Sarai, New Delhi - 110016, INDIA

licensing issues holding up system expansion for years. It is

very difficult to acquire new right-of-way (ROW). Increased

demand on transmission, significant deviation from planned

system and the need to provide open access to generating

companies and customers, all together have created

tendencies towards reduced security and poor quality of

supply. However, with more and more generation coming up

and requiring haulage of large amount of power over long

distance, it has become difficult to plan further system on

account of congestion, leaving practically no corridor. This

has lead to the development of several innovative means for

optimum utilization of ROW by enhancing the capability of

existing transmission system. To meet this goal, technology

like, Flexible AC Transmission System (FACTS) is a

possible solution towards enhancing loadability of lines.

The FACTS devices use high-power electronics to achieve

control and to increase the capacity of ac transmission

system, restriction only being the thermal limit. This can be

accomplished using a wide variety of methods employing

series or shunt controlled devices. There are numerous

references [l] - [5] which give details of the characteristics

of FACTS devices and they have their relative merits.

FACTS devices: Static Var Compensator (SVC)

Static Compensator (STATCOM) Thyristor Controlled Series Capacitor (TCSC)

Unified Power Flow Controller (UPFC) Inter-line Power Flow Controller (IPFC)

FACTS like devices are: High Voltage DC (HVDC) Phase Shifting Transformer Switched Capacitors (Series or Shunt) Switched Reactors (Series or Shunt)

0-7803-7525-4/02/$17.00 0 2002 IEEE. 237

Flexible AC Transmission System (FACTS) Technology is

an emerging technology for enhancing the capability of

existing transmission system. With the installation of

FACTS, it is possible to increase the power with small

additional investment and within short gestation period as

compared to building of additional lines. It enhances the

transfer capability of existing transmission system under

steady state as well as improves system security under

dynamic contingencies. The basic concept in different forms

has been widely attempted in North America. First SVC for

voltage control was demonstrated in Nebraska in 1974. To

give a few examples, there are TCSC of 202 MVAR at Slatt

500 kV Substation of Bonneville Power Administration in

Oregon [6], STATCOM at 161 kV Sullivan Substation of

Tennessee Valley Authority having capacity +/- 100 MVAR

set up in 1995 [7], UPFC of American Electric Power

Company at 138 kV Inez Substation (Kentucky) [8] with a

novel concept of controlling voltage, line impedance and

phase angle with a total rating of +/- 320 MVAR, IPFC (with

development in progress that will eventually enable more

flexibility in sharing of power through parallel lines too) at

345 kV Marcy Sub-station of New York Power Authority.

In India at the time of independence, the power supply

was essentially locally oriented and the highest system

voltage was 132 kV. Subsequently, it rose to 220 kV and

finally to 400 kV level. Also 800 kV transmission system has

been constructed, but charged at 400 kV level for operation at

present. There is wide gap between demand for power and

generated power and the growth rate of electrical energy

requirement is about 8% per annum. To keep pace with the

growing demand, the generating capacity addition proposed

by end of 9Ih Five Year Plan (1997-2002), loLh and 1lLh Plan

are about 40,000 MW, 55,000 MW and 60,000 MW

respectively. The construction of generating station and

associated transmission system is capital intensive with long

gestation period, Nevertheless, environmental and ecological

consideration and regulatory authorization process including

ROW problems are strongly limiting or delaying installation

of new facilities in the transmission network.

Under these circumstances, it is important to utilize

existing systems as efficiently as possible, to increase both

the capacity and the quality of present transmission networks,

even if for limited period, through various innovative

methods with minimum investment. Problems arising from

delays or difficulty to add new transmission facilities could

be partially or completely overcome by increasing the

flexibility of the existing network. Hence, possibility of

power flow control in AC transmission network is getting

more and more attractive. Flexible AC Transmission System

technology is an evolving technology based solution for

power transmission at small additional investment with a

short gestation period. FACTS has been defined by the IEEE

as “Alternating Current Transmission Systems incorporating

power electronics based and other static controllers to

enhance controllability and increase power transfer

capability”. Thus FACTS increases the flexibility of power

systems, make them more controllable and allow increased

utilization of existing network closer to its thermal loading

capacity without jeopardizing the stability. Based on the

experience gained by power utilities of world and system

studies conducted in India, a FACTS project has been

undertaken in September 2000 which is an in-house

development effort on 400 kV line between Kanpur (Uttar

Pradesh) and Ballabgarh (Haryana) in the Northern Grid.

The project is proposed to be implemented in two phases.

Phase-I covers commissioning of 35% Fixed Series

Compensation (FSC) consisting of two banks of 27% and

8%. Phase-I1 covers commissioning of Thyristor Controlled

Series Capacitor (TCSC), under an R&D project.

11. SCENARIO IN INDIA

It is well known that proper active and reactive power

management in an extensive electrical network can lead to

reduced system losses and improved voltage profile. By

judiciously applying series compensation, active power

transfer and reactive power consumption of the transmission

lines can be controlled.

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With the advantages envisaged, application of series

compensation on following 400 kV corridors were considered.

i) Itarsi-Indore double circuit line

ii) Satpura-Indore line

iii) Bhilai-Satpura line

iv) Bhilai-Chandrapur double circuit line

v) Bhilai-Satpura and Satpura-Koradi lines

vi) Vindhyachal-Jabalpur double circuit line

vii) Dadri-Malerkotla line

viii) Kanpur-Ballabhgarh line

Series compensation of 400 kV lines shows promising

results in terms of improvement in power hand!ing capacity of

lines and improvement in voltage profile together with system

loss reduction which pays back the cost of series

compensation scheme. Based on the results of system studies

and other technical and economical considerations a project

has been undertaken on a 400 kV Kanpur - Ballabhgarh line at

Ballabhgarh end in the Northern Grid. This is the first of its

kind. As so far Indian Engineers had the experience of

working with SVCs, both in power system and industrial

installations.

Power carrying capacity is envisaged to be increased from

400 to 600 MW. The controller so designed has features to

damp low frequency inter-area oscillations following outage

of a parallel AC line between Kanpur & Agra (also in Uttar

Pradesh) or one pole of parallel HVDC line at +/-500 kV.

Cases

Base case 35% series compensation in Agra-Ballahharh line 47% series compensatio* in Kanpur- Ballabhgarh line

Kanpur- Ballabhgarh

Outage of Kanpur-Agra

Outage of

111. PLANNING S'TUDIES

Power Flow (MW) Kanpur - Kanpur - Agra - Ballabhgarh Agra Ballabhgarh 351 474 24 1 490 461 184

566 398 199

599 31 1

588 142

Kanpur-Ballabhgarh and Kanpur-Agra lines in Uttar

Pradesh together carry about 800 MW power from Singrauli - Rihand mine-mouth generation belt to western part of Uttar

Pradesh and Rajasthan. Kanpur-Ballabhgarh is a 400 kV,

400 km single circuit line and Kanpur-Agra is 400 kV, 250

km single circuit line. Ballabhgarh and Agra are also

connected through a single circuit line which is generally

lightly loaded as it serves as a tie line between Kanpur-

I Cases

Ballabhgarh-Jaipur axis and Kanpur-Agra-Jaipur axis.

Power Flow (M W) I I Kanpur- I Arra- Kanwr -

t I Kanour-

Base case 35% series

Ballibhgarh 415 Base case

35% series 5 73

Ballabhgarh Agra Ballabhgarh 516 419 523 730 356 486

Cases Power Flow (MW)

Ballabhgarh

461 184 compensation in Agra-Ballabhgarh line 47% series compensatio* in Kanpur-

658

Ballabhgarh line Outage of Kanpur- Ballabhgarh line Outage of Kanpur-Agra line

TABLE I1 ANIA - I I & AUKAIYA - II TIMI: FKAMI: (2001 -2002)

I line

TABLE 111 RIIIANI)-II TIMI: FKAMIC (2003-2004)

compensation in Agra-Ballabharh I I line 47% series I 850 I 322 I 467

KanDur- I I I compensatio* in

Ballabhgarh line Outage of Kanpur- Ballabhgarh Outage of Kanpur- Agra

* operational for restricted time only

239

Details of studies carried out by PowerGrid Corporation of

India Ltd. for this region show that the line after installation

of TCSC would help in preventing collapse of the grid under

similar situation experienced in the last two grid collapses in

the Northern Grid. Results of studies are summarized through

Table I, I1 and 111.

IV. DESIGN PARAMETERS

Phase-I covers design development, supply erection and

commissioning of Fixed Series Capacitor consisting of banks

of 27% and 8% with associated protection equipment. Phase-

11 covers design, development, supply, erection and

commissioning of thyristor controller for 8% series capacitor

bank of Phase-I to be converted to variable bank with range

from 8 to 20%. Project details and equipment parameters are

given in Appendix. Single Line diagram of TCSC scheme

is given in Fig. 1.

The broad parameters of main equipment are given below:

System parameters

Rated voltage Nominal reactive power Continuous effective impedance Maximum dynamic impedance Rated current Rated continuous voltage TCR inductance /phase

27% Capacitor bank

420 kV 15 1.6 Mvar

35.1 ohm 35.1 ohm

1200 A 42.2 kV

8% Capacitor bank

420 kV 79.87 Mvar

10.4 ohm 26 ohm 1600 A 16.6 kV 4.4 mH

v. PROGRESS IN IMPLEMENTATION

All equipment pertaining to Fixed Series Compensation have been completed and the system is likely to be charged in March 2002. Photographs depicting views of platform mounted equipment are shown in in Fig. 2 and 3.

VI. WORK TO BE DONE FURTHER

Under Phase-11, ratings of thyristor, TCR (thyristor controlled reactor) shall be finalized and design of their controllers shall be completed. These equipment shall be installed, erected and commissioned by October 2002.

8% 4PRVIBLE COMPENSATION r-b+-

LlhE cr PII cr 198

6"' f 2998- CS

FPOhr KAWJR ---

Fig. 1 . Single line diagram of TCSC scheme

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Fig. 2. Mounting on insulated platform

VII. CONCLUSION

With the installation of Fixed Series Capacitor immediately while loadability of a transmission corridor between eastern and western part of northern grid will increase, incorporation of TCSC further in this system will improve dynamic performance under various contingencies of operation and may avoid disintegration of grid as faced a number of times in the past.

VIII. APPENDIX

A. PROJECT DETAILS The broad parameters are as follows:-

Line length 390 km Type of conductor Line reactance 0.332 ohms/km Rated voltage 420 kV System frequency 50 Hz System short-circuit level

Twin ACSR Moose

40 kA for 1 s

B. SITE CONDITIONS

Maximum ambient temperature 48°C

Fig. 3. View over the platform

Minimum ambient temperature 1°C Altitude less than 1000 m Humidity 100 % Pollution Heavy Seismic acceleration 0.3g horizontal

C. EQUIPMENT PARAMETERS

In the series compensated schemes there are two types of equipment

Ground mounted Platform mounted

1) Ground Mounted Equipment:

Bypass circuit breaker

The bypass circuit breaker shall be provided for the following purpose:

a) Deliberate bypassing b) Bypassing through automatic protection c) Manual insertion

24 1

d) Automatic re-insertion following line faults and [7] C. Schauder, M.Gernhardt, E.Stacey, T. Lemak, L. Gygugyi, T.W. Cease, and A. Edris, “TVA STATCOM Project: design, installation

and commissioning”, C E R E Meeting, Paris, August, 1996, Paper 14-106. [8] A.Edris, A. S.Mehraban, M.Rahman, L.Gyugyi, S.Arabi, and

T.Reitman, “Controlling the flow of real and reactive Power”, IEEE Computer Application in Power, vol. 1 1 , no. I , Jan 1998.

disturbances

Technical particulars of the circuit breaker

Rated voltage Rated current

420 kV 2000 A

Type of circuit breaker SF6 Duty cycle of mechanism c-0-c Technical particulars of disconnecting switch

420 kV, 2000 A, outdoor, triple pole. Both main switch earth switch are motor-operated.

2) Plalform Mounted Equipment:

Insulated platform

and

XI. BIOGRAPHIES

Subrata Mukhopadhyay (S’70, M’70, SM’80) was born in Asansol, India in 1947. He graduated in Electrical Engineering from Jadavpur University, Calcutta in 1968; had his Master’s and Doctorate Degrees from Indian Institute of Technology, Kharagpur and Roorkee in 1970 and 1979 respectively. His employment experience over 31 years includes teaching in Roorkee and power system planning, design and operation with the Central Electricity Authority of Government of India. He has authored two books and twenty one papers, won IEEE Third Millennium Medal in 2000 and is a Fellow of the Institution of Engineers (India).

-3 Single phase, galvanized steel platforms shall be provided in series capacitor bank installation. These platforms are independently supported on suitable number of 400 kV post insulators. Platform mounted main equipment are as follows:

Ashok K. Tripathy (M’98, SM2000) born in 1948, obtained Bachelor‘s and Master’s Degrees in Electrical Power from Regional Engineering College, Rourkela and Indian Institute of Science, Bangalore in 1969 and 1971 respectively. After a brief spell of working with

a) Capacitor bank the Steel Authority of India Ltd., he is working b) Sparkgap with the Bharat Heavy Electricals Ltd. for the

last 26 years in the field of series compensation c) and HVDC. He is the Project Director of National HVDC Project and a Member of Study

d) Metal Oxide Varistor Committee in CIGRE. His current interest e) Current transformers includes introduction of FACTS in Indian power

system. He is one of the Vice Presidents of the Indian EMTP User Group. €) Control & protection equipment

g ) Thyristor valves

Damping circuit (damping reactor+ damping resistor)

h) Thyristor controlled reactors

IX. ACKNOWLEDGEMENT

The project is being financed by Bharat Heavy Electricals Ltd., Ministry of Power, and Ministry of Communications and Information Technology of the Government of India.

The authors are indebted to their organizations Central Electricity Authority, Bharat Heavy Electricals Ltd. and PowerGrid Corporation of India Ltd. for the encouragement being received during the execution of the project.

X. REFERENCES

[ I ] N.G.Hingorani, “Flexible AC transmission”, IEEE Spectrum, vol. 30, no. 4, Apr. 1993.

[2] N.G.Hingorani, and L. Gyugyi, “Understanding FACTS concepts and technology of flexible AC transmission system”, Piscataway: IEEE Press, 1999.

[3] R.Adapa, “Summary of EPRl’s FACTS system Studies”, C E R E SC 14 International colloquium on HVDC & FACTS, Montreal, September, 199s.

[4] N.G.Hingorani, “Power Electronics in AC Transmission System“, CIGRE special Report 1996.

[SI K.R.Padiyar, and A.M.Kulkarni, “Application of static condenser for enhancing power transfer in. long ,AC lines”, C E R E Symposium on Power Electronics in Electric Power System, Tokyo, May 1995.

[6] V.Venkatasubramanium , and C.W.Taylor, “Improving Pacific intertie stability using Slatt thyristor controlled series compensation, detailed summary”, submitted to IEEE PES WM, Jan 2000, Singapore.

V.&Prasher having been graduated in Electrical Engineering in 1971 worked in the Electrical Design Groups of Central Electricity Authority and National Thermal Power Corporation Ltd. up to 1983. Thereafter, he took over as head of the HVDC Engineering Group in the Corporation and subsequently worked at site for ten years in the construction, testing, commissioning and then in operation and maintenance of Rihand-Delhi HVDC link. After absorption in the PowerGrid Corporation of India Ltd. he executed a number of EHV AC Substations and HVDC links. Presently he is in- charge of Load Dispatch, Communications and HVDC Departments. He is a regular member of Study Committee 14 of CIGRE on HVDC and Power Electronics.

Krishan K. Arya born in 1958, obtained his Bachelor’s and Master’s Degrees in Electrical Engineering from Delhi College of Engineering and Indian Institute of Technology, Delhi in 1979 and 1985 respectively. He is working in the Central Electricity Authority for the last 22 years in the area of power system design. His field of interest is in the area of design and engineering of EHV Substation, new technologies, like, development of HVDC, FACTS, etc.

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