Optimal Placement of TCSC in Power MarketCompensator (SSSC) and Unified Power Flow controller (UPFC)...

International Journal of Electrical Energy, Vol. 3, No. 1, March 2015

©2015 International Journal of Electrical Energy 43doi: 10.12720/ijoee.3.1.43-47

Optimal Placement of TCSC in Power Market

Tran Phuong NamHue Industrial College, Hue, Vietnam

Email: [email protected]

Dinh Thanh VietDanang University of Technology, Danang, Vietnam


La Van UtHanoi University of Science and Technology, Hanoi, Vietnam


Abstract—Nowadays, the operation of power systems in the

power market model has been researched and applied by

many countries. At the same time, power systems operation

becomes more important as the load demand increases all

over the world. This change ensure the power system

security as well as ensure the power market economy.

Thyristor controlled series compensator (TCSC) devices can

play very important role in power system congestion

management. Due to high capital investment, it is necessary

to locate these devices optimally in the power system. The

scope of this paper is to decide optimal location of TCSC by

congestion improvement and social welfare index. The

effectiveness of proposed method is demonstrated on IEEE-

39 bus test power system.

Index Terms—power market, power system, TCSC,

congestion, social welfare

I. INTRODUCTION

With the rapid development of power electronics,

Flexible AC Transmission systems (FACTS) devices

have been proposed and implemented in power systems.

These devices are new technology based on power

electronics that are capable of altering voltage, phase

angle and impedance at particular points in power

systems. On the other hand, the fast development of

power electronic technology has made FACTS promising

solution of future power system. FACTS controllers such

as Static Synchronous Compensator (STATCOM), Static

VAR Compensator (SVC), Thyristor Controlled Series

Compensator (TCSC), Static Synchronous Series

Compensator (SSSC) and Unified Power Flow controller

(UPFC) are able to change the network parameters in a

fast and effective way in order to achieve better system

performance [1]. These controllers are used for enhancing

dynamic performance of power systems in terms of

voltage/angle stability while improving the power

transfer capability and voltage profile in steady-state

conditions. FACTS devices are cost effective alternatives

to new transmission line construction. Reactive power

Manuscript received March 3, 2015; revised June 16, 2015.

compensation is provided to minimize power

transmission losses, to maintain power transmission

capability and to maintain the supply voltage. Particularly

with the deregulation of the electricity market, there is an

increasing interest in using FACTS devices in the

operation and control of power systems.

In this paper, the congestion and the social welfare for

the optimal placement of considering TCSC have been

presented.

II. POWER MARKET

In the power pool market, Generation Companies

(GenCos) and the Distribution Companies (DisCos)

submit the quotations for Market Operation (MO) for the

power market (Fig. 1 and Fig. 2). Offers are submitted in

blocks of price quantity pairs. Power market allows

submitting many blocks for GenCos and DisCos [2].

Figure 1. Bid and auction in the power market.

Figure 2. Power pool market.


©2015 International Journal of Electrical Energy 44

The quotations of the GenCos and DisCos from

scheduled supplies can be approximated to the quadratic

function or higher degree function of capacity [2]:

2

Gi Gi Gi Gi Gi GiC a b P c P (1)

2

DiDiDiDiDiDi PcPbaB (2)

The objective function is a minimum of social welfare

in total:

1 1

min( ( ) ( ))G D

n n

Gi Gi Di Di

i i

C P B P

(3)

Locational marginal pricing (LMP) at a location (bus)

of a transmission network is defined to be the minimal

additional system cost required to supply an additional

increment of electricity to this location. LMP at Busi is

three components included in the marginal price at

reference bus, marginal loss cost from reference bus to

Busi and marginal congestion price from reference bus to

Busi [2].

i i ref lossi congestioniLMP (4)

1

nijloss

i i ref ref j

ji i

PPLMP

P P

(5)

III. THYRISTOR CONTROLLED SERIES CAPACITOR

Generally, TCSC is a series compensator as a

capacitive as well as an inductive element that can be

added to a transmission line. Based upon the adding a

TCSC to a transmission line the admittance matrix of the

system should be modified. The main circuit of a TCSC

is shown in Fig. 3. The TCSC consists of three main

components: capacitor bank C, bypass inductor L and

bidirectional thyristors SCR1 and SCR2. The firing

angles of the thyristors are controlled to adjust the TCSC

reactance in accordance with a system control algorithm,

normally in response to some system parameter variations.

According to the variation of the thyristor firing angle or

conduction angle, this process can be modeled as a fast

switch between corresponding reactances offered to the

power system [1].

Figure 3. Model of TCSC device.

Table I shows the comparison of FACTS devices of

power system with series and shunt FACTS devices.

From Table I it is investigated that TCSC and UPFC are

the effective device for load flow and stability

enhancement of power system. On the other hand SVC

and SSSC are the effective device for voltage control.

TABLE I. CAPABILITIES OF DIFFERENT FACTS DEVICES

CONTROLLERS

Power flow control

Voltage control

Transient stability

Dynamic stability

UPFC High High Medium Medium

TCSC Medium Low High Medium

SVC Low High Low Medium

SSSC Low High Medium Medium

The cost functions of SVC is developed as Fig. 4 [3]:

Figure 4. Cost functions of the FACTS devices: SVC, TCSC, UPFC(upper and lower limit)

IV. CALCULATION

This paper proposed calculation model with IEEE 39

bus test power system as Fig. 5 [4]:

Figure 5. IEEE 39 bus test power system

From Fig. 6 and Fig. 7, if TCSC connected to line 4-14,

congestion improvement at lines will be more efficient

than the other cases (congestion of lines 5-6, 10-11 and 6-

11 were reduced).



Figure 6. Without TCSC connection

Figure 7. Congestion in power market (TCSC at line 4-14)

Values increase in profit of GenCo and DisCo with

TCSC connection:

0TCSC

GenCo GenCo GenCo (6)

0TCSC

DisCo DisCo GenCo (7)

Social welfare with TCSC connection:

1 1

G Dn nh

Social GenCo DisCo

i i

0 0

1 1

( ) ( )G Dn n

TCSC TCSC

GenCo GenCo DisCo DisCo

i i

(8)

Therefore, annual social welfare from use of TCSC in

year can be determined as:

*8760*year h

Social Socialu (9)

According to [3], the cost functions of TCSC is

developed as follows:

2

0153.75 0.713* 0.0015*

TCSC TCSC TCSCC S S (10)

Therefore, annual capital cost of TCSC in $/year can

be found as [5]:

0

*(1 )* *1000*

(1 ) 1

n

year

TCSC TCSC TCSC n

r rC C S

r

(11)

Factors can be found as [6]:

Project lifetime (n): 5 year; discount rate (r): 10%;

average utilization (u): 40%.

From (9) and (11), welfare-cost index of TCSC in year

is proposed in (12):

year

Social

year

TCSC TCSC

B

C C

(12)

TABLE II. TARGETS OF GENCOS WITHOUT TCSC CONNECTION

GenCo P (MW)LMP

($/MWh)

Revenue

($/h)Cost ($/h)

Profit

($/h)

G30 350 646.61 226314 4743 221571

G31 683 17.45 11915 7655 4260

G32 734 16.50 12103 7434 4669

G33 732 493.92 361549 8263 353287

G34 608 496.24 301714 6508 295206

G35 695 16.03 11133 6911 4222

G36 660 105.46 69604 7524 62080

G37 640 603.39 386170 6810 379360

G38 930 555.33 516457 9495 506962

G39 1100 843.31 927641 11550 916091

Σ 7131 3794 2824598 76892 2747707

TABLE III. TARGETS OF GENCOS WITH TCSC CONNECTION AT LINE

4-14

GenCo P (MW)LMP

($/MWh)

Revenue

($/h)Cost ($/h)

Profit

($/h)

G30 350 630 220465 4743 215723

G31 783 22 17272 9633 7639

G32 622 17 10261 5609 4652

G33 732 575 421164 8263 412901

G34 608 578 351606 6508 345098

G35 706 16 11312 7093 4219

G36 660 120 79398 7524 71874

G37 640 597 382304 6810 375494

G38 930 577 536266 9495 526771

G39 1100 727 800063 11550 788513

Σ 7130 3860 2830112 77227 2752884



Also, Table II and Table III show the indexes of

GenCos for TCSC connection at line 4-14 and vice versa

for TCSC disconnection. If GenCos participate in the

power market, they will have benefit from the law of

supply and demand of the market. GenCos can actively

earn profit by bidding strategy.

Moreover, similar analysis of total targets of Discos

buses with TCSC connection as well as disconnection in

the power market (Table IV).

TABLE IV. TARGETS OF DISCOS WITHOUT AND WITH TCSCCONNECTION AT LINE 4-14

GenCoP

(MW)

LMP

($/MWh)

Revenue

($/h)

Cost

($/h)

Profit

($/h)

Without 7072 10572 4585347 227703 -4357645

With TCSC 7071 10876 4514656 227703 -4286953

Furthermore, analysis of annual social welfare from

use of TCSC in $/year can be determined in Table V. If

GenCos participate in the power market, they will have

benefit from the law of supply and demand of the market.

GenCos can actively earn profit by bidding strategy.

TABLE V. SOCIAL WELFARE WITH TCSC CONNECTION CASES

Case GenCo DisCo

year

Social

($/h) ($/h) ($/year)

TCSC at line 15-16 -27386 32316 17271216

TCSC at line 4-14 5178 70691 265844976

TCSC at line 3-4 283128 -418172 -473194176

TCSC at line 3-18 262110 -396102 -469504464

TCSC at line 1-39 268756 -400954 -463221792

At the same time, Table VI shows the calculation of annual cost of TCSC. Comparison of Table V and Table VI clearly shows that the social welfare generated due to TCSC far exceeds the annual capital cost of TCSC with TCSC connection at line 15-16 and line 4-14. This showsthat TCSC is economically beneficial to be used for congestion management.

TABLE VI. ANNUAL COST OF TCSC WITH TCSC CONNECTION CASES

CaseTCSCS TCSCC0

year

TCSCC

(MVAr) ($/kVAr) ($/year)

TCSC at line 15-16 10 147 387782

TCSC at line 4-14 9.6 147 372270

TCSC at line 3-4 32.7 132 1138653

TCSC at line 3-18 1 153 40361

TCSC at line 1-39 13.5 144 512821

From Table VII, the welfare-cost index indicates the

positive results conducted from different TCSC

connection cases. It is clear to see that the welfare-cost

factor of TCSC at line 4-14 is the highest.

TABLE VII. WELFARE-COST FACTOR WITH TCSC CONNECTION CASES

Caseyear

Social

year

TCSCC

TCSC

B

C

($/year) ($/year)

TCSC at line 15-16 17271216 387782 45

TCSC at line 4-14 265844976 372270 714

TCSC at line 3-4 -473194176 1138653 -416

TCSC at line 3-18 -469504464 40361 -11633

TCSC at line 1-39 -463221792 512821 -903

To sum up, if TCSC is connected to reasonable lines in

the power market, congestion and social welfare has been

improved effectively. The annual total social welfare is

bigger than the annual cost of TCSC as well as the high

results of welfare-cost index is feasible.

V. CONCLUSION

This paper has analyzed the optimal placement of

TCSC that improve congestion and social welfare. If

TCSC is allocated at reasonable lines, it will effectively

improve the targets of system and market. This also

shows that the proposed methodology can be employed to

secure the investment on TCSC. Therefore, the proposal

of the welfare-cost index for optimal placement of TCSC

is proper.

ACKNOWLEDGMENT

The authors would like to thank NAFOSTED for

financial support of authors’ attendance.

REFERENCES

[1] E. Acha, C. R. Fuerte, H. Ambriz, and C. Angeles, FACTS:

Modelling and Simulation in Power Networks, John Willey & Sons Publishers, 2004.

[2] D. Kirschen and G. Strbac, Fundamentals of Power System Economics, John Wiley & Sons Publishers, 2004.

[3] G. C. Stamtsis, Power Transmission Cost Calculation in

Deregulated Electricity Market, Berlin: Logos Verlag Berlin, 2004.[4] M. A. Pai, Energy Function Analysis for Power System Stability,

Kluwer Academic Publishers, 1989.

[5] N. Acharya and N. Mithulananthan, “Locating series FACTS

devices for congestion management in deregulated electricity

markets,” Electric Power Systems Research, vol. 77, pp. 352-360, 2007.

[6] N. Mithulananthan and N. Acharya, “A proposal for investment recovery of FACTS devices in deregulated electricity markets,”

Electric Power Systems Research, vol. 77, pp. 695-703, 2006.

Tran Phuong Nam was born in Vietnam, on 1980. He received the B.S. and M.S. degrees

in power systems from Danang University of

Technology, Vietnam, in 2004 and 2011. His research interests lie in operation and control

of power systems, new optimization theory for power systems, optimal control of FACTS,

voltage stability of power systems with

FACTS, power electronics and energy quality,

intelligent measurement and control of power

systems, intelligent systems, optimization of large-scale systems, production costing and pricing, and strategic bidding and scheduling in

the deregulated electric power markets.



Dinh Thanh Viet was born in Vietnam, on 1970. He received the PhD. degrees in power

systems from Visnik Vinnitsya Polytechnic

Institute, Ukraine, in 1997. He is working with the Electrical Engineering Department,

Danang, Vietnam. His research interests lie in analys and control of power systems,

intelligent monitoring measurement of

electrical machine, intelligent systems, calculation and analys power market.

La Van Ut was born in Vietnam, on 1946. He received the PhD. degrees in power systems

from Moscow Power Engineering Institute,

Russia, in 1983. He is working with the Electrical Engineering Department, Hanoi,

Vietnam. His research interests lie in design and operation of power system, analys and

control of power systems stability,

optimization of power system, FACTS device, calculation and operation of hydro power

plant, calculation and analys power markets.

http://www.ieeexplore.ieee.org/xpl/RecentCon.jsp?punumber=8322








Optimal Placement of TCSC in Power MarketCompensator (SSSC) and Unified Power Flow controller (UPFC)...

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