Optimal Location Of TCSC For Congestion Management In Restructured Power System | Open Access Journals

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Optimal Location Of TCSC For Congestion Management In Restructured Power System

Dipak S. Yeole1, Dr.P.K.Katti2
  1. M.Tech Student,Department of Electrical Engineering, Dr. Babasaheb Ambedkar Technological University, Lonere, Maharashtra, (India).
  2. Professor,Department of Electrical Engineering, Dr. Babasaheb Ambedkar Technological University, Lonere, Maharashtra, (India).
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Traditionally electric power sector had over all activities in generation, transmission and also in distribution of power within its domain of operation. Such utilities referred to as vertically integrated utility (VIU).Due to continuous increase in industrialization and urbanization there is need of electrical energy. This gives rise into rapid growth of power system. The main focus of engineers to reshape three components of VIU. The restructuring is used to increase customer focus, power system performance and reduce the cost revenue. Congestion is one of the technical issue in power system restructuring. In restructured power system transmission congestion occurs when there is insufficient transmission capacity to simultaneously accommodate all constraints for transmission of a line. This paper proposes to relieve congestion using TCSC device without affecting on economic matter. Further a methods to determine the optimal location of TCSC has been suggested based on reduction of total system reactive power loss.


Congestion management, optimal location, restructured power system, Thyristor Controlled Series Capacitor (TCSC), Vertically Integrated Utility (VIU).


Electricity is the most important and essential need of Today’s society. Near 1980’s, major challenges have been introduced into restructure of vertically integrated utility (VIU).The main reason of restructuring is to improve efficiency and make continuity in operation of the power. The success of reforms in communication sector and airlines shows importance of deregulation. United Kingdom was first to restructure. Then this same followed by Norway, Australia, New Zealand and United States. In India, during mid-1990’s Orissa starts first to restructure then same followed by Andhra Pradesh, Uttar Pradesh, Rajasthan, Haryana and Maharashtra [1]. There are several complexities in restructure of electric utility. As electricity cannot be stored easily, and transportation of electricity is followed by physical laws .This have to be satisfied at all times in order to maintain reliability and security of the power system. Due to violation of this constraints, leads to unwanted voltage profile and congestion in transmission lines. Congestion management deals with the relief of congested transmission networks in restructured power system. If congestion is not relief then it may lead to tripping of overloaded lines, consequential tripping of other lines and in some cases to voltage stability problems. Hence to avoid such problem congestion need to be solve.To operate restructure power system in secure state independent system operator (ISO) or transmission system operator (TSO)has to relieve the congestion, for this ISO or TSO can use following methods:[2]
1) Cost free methods:
i) Operation of transformers taps/phase shifters
ii) Outageing of Congested lines
iii) Operation of FACTS devices particularly Series
FACTS devices.
2) Cost based methods:
i) Load curtailment
ii) Rescheduling generation.
Cost free methods have more advantageous than cost based such as without disturbing economic matter. FACTS device, [3] like Thyristor Controlled Series Capacitor (TCSC) have found to be more useful than other devices. In this respect, looking from literature objective of problem formulation for transmission congestion management is to provide relieve to congested line through optimal location of TCSC has been proposed. The proposed mechanism would be realized through proper computational techniques so that the power flow through designated path relieving line congestion.


A. Construction and Characteristics

Fig.1 shows TCSC construction, capacitor is in series with line and Thyristor controlled inductorconnected in parallel with it. TCSC is under series compensator device which increases transmission linecapacity by decreasing lines series impedances also increase network reliability. The bi-directional thyristor valve is fired with an angle α ranging between 90° and 180° with respect to the capacitor voltage.Because of this TCSC becomes much economic than other compensating FACTS devices.
Fig. 2 shows impedance characteristics of a TCSC device [3] [4].It is drawn effective reactance of TCSC Vs firing angle α. The effective reactance of TCSC starts increasing from XL value to till occurrence of parallel resonance condition XL (α) =XC, theoretically XTCSC is an infinity. This region is an inductive region. Further increasing value of XL (α) gives capacitive region. Thus, following impedance characteristics of TCSC shows that both capacitive and inductive region are possible though varying firing angle (α).
While selecting inductance, XLshould be sufficiently smaller than that of the capacitor XC. The capacitive region is possible in impedance characteristics, if XC< XL. In shunt circuit, effective value of reactance follows the lesser reactance present in branch. Hence only one capacitive reactance region will appears. Also XL should not be equal to XC value; or else a resonance develops that result in infinite impedance an unacceptable condition.

B. Static Modelling

Following Fig. 3 (a) shows a simple transmission line represented by its lumped πequivalent parameters connected between bus-a and bus-b. Let complex voltage at bus-a and bus-b are Va∠δa and Vb∠δb respectively. The real and reactive power flow from bus-a to bus-b can be written as follows, [5] [6] [7]


To find out optimal location of TCSC, the analysis has been implemented on IEEE 14-bus system as shown in Fig.5 below.MATLAB has been used for simulation.
The sensitive of real power flow performance index sensitivity indices with respect to TCSC control parameter has been calculated and are shown in Table I. The sensitive lines are highlighted in Table I. It can be observed from Table I that line 19 is more sensitive as per reduction of total system reactive power loss method. Power flow result after placing TCSC in line 19 is as shown in Table II.The value of control parameter of TCSC for computing power flow is taken as 0.139916 p.u. It can be observed from Table IIcongestion is relieved in line 17after placing TCSC.


From above discussion, it is observed that congestion is major problem in restructured power system and need to be solve.TCSC device is found to be useful to reduce power flow in heavily congested lines. Because of high cost of TCSC device, it is important to follow flow chart given in this paper to obtain optimal location of TCSC device in given network.
The results of IEEE14bus presented in this paper shows that the method would very effective to solve congestion problem with optimal placement TCSC device.


  1. Text book by A.R.Abhyankar, Prof.S.A.Khaparde, “Introduction toderegulation in power industry”
  2. L.Rajalakshmi, M.V.Suganyadevi, S.Parameswari “CongestionManagement in Deregulated Power System by Locating SeriesFACTS Devices” International Journal of Computer Applications(0975 – 8887) Volume 13– No.8, January 2011
  3. Text Book by N.G.Higorani& Laszlo Gyugyi “UnderstandingFACTS Concept and technology of Flexible AC TransmissionSystems”
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