In an A.C Transmission system power flow can be controlled by injecting a compensating voltage in series with the line. Thyristor Controlled series compensators (TCSC) are utilized as a conventional means for the purpose. This paper utilizes the steady state model of Thyristor controlled series capacitor and a unified power flow controller for series voltage compensation, and evaluating their range of power flow control for simple network. The models are incorporated into the existing Newton Raphson load flow algorithm. The iterative equations of the Newton Raphson load flow algorithm are modified by the device parameters and the combined set of power flow equations and the TCSC control equations are solved for convergence of the formula. Matlab codes are utilized for the implementation of the devices in the Newton-Raphson algorithm. Power flow control ranges are evaluated for standard 5 bus system. Results are reported and studies are presented to illustrate the power flow capabilities of TCSC. Keywords: Converters, Control Strategy, MATLAB, Newton Raphson algorithm, Power flow, TCS

Choudhary, Shivani

Jain, Monika

Mubeen, Samina.E.

English

International Institute for Science, Technology and Education (IISTE): E-Journals

Innovative Systems Design and Engineering                                                                  www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online)  Vol.4, No.6, 2013 - Selected from International Conference on Recent Trends in Applied Sciences with Engineering Applications  44 Evaluation of TCSC Power flow control Capability  Shivani Choudhary  Oriental Institute of Science & Technology, RGPV University Oriental Campus, Thakral Nagar, Raisen Road, Bhopal(M.P.)  E-mail:shivani.choudhary28@Gmail.com Samina.E.Mubeen  Radharaman Engineering College, RGPV University Bhadbhada Road, Ratibad, Bhopal (M.P.) Monika Jain Oriental Institute of Science & Technology, RGPV University Oriental Campus, Thakral Nagar, Raisen Road, Bhopal (M.P.)  E-mail:shivani.choudhary28@Gmail.com  Abstract In an A.C Transmission system power flow can be controlled by injecting a compensating voltage in series with the line. Thyristor Controlled series compensators (TCSC) are utilized as a conventional means for the purpose. This paper utilizes the steady state model of Thyristor controlled series capacitor and a unified power flow controller for series voltage compensation, and evaluating their range of power flow control for simple network. The models are incorporated into the existing Newton Raphson load flow algorithm. The iterative equations of the Newton Raphson load flow algorithm are modified by the device parameters and the combined set of power flow equations and the TCSC control equations are solved for convergence of the formula. Matlab codes are utilized for the implementation of the devices in the Newton-Raphson algorithm. Power flow control ranges are evaluated for standard 5 bus system. Results are reported and studies are presented to illustrate the power flow capabilities of TCSC.  Keywords: Converters, Control Strategy, MATLAB, Newton Raphson algorithm, Power flow, TCSC  I.  Introduction OWING to the higher industrial demands and deregulation of the power supply industry the transmission facilities are being overused. This provides the momentum for exploring new ways of maximizing the power transfers of existing transmission facilities while, at the same time, maintaining acceptable levels of network reliability and stability. This scenario makes necessary the development of high performance control of the power network. Recent advancement in power electronics has proven to satisfy this need by introducing the concept of flexible AC transmission system (FACTS). The FACTS controllers are used in regulating the power flows, transmission voltages and mitigate the dynamic disturbance. Since its inception the FACTS devices has developed in steps, the first generation being mechanically controlled capacitors and inductors. The second generation of FACTS devices replaced the mechanical switches by the thyristor valve control. This gave a marked improvement in the speed and the enhancement in concept to mitigate the disturbances.  Power flow in a transmission line can be controlled by regulating the voltage at the two ends of the line, the phase angle or the reactance of the line. Thyristor controlled series compensators works on the principal of regulating the voltage of the transmission line by injecting voltage employing capacitor or inductor. In order to fully investigate the impact of this device on power system effectively, it is essential to formulate their correct and appropriate model. Generally there are three types of model of FACTS devices available in the literature. (i) Steady state model for system study state evaluation. (ii)Electromagnetic model for detailed equipment level investigation.         (iii) Dynamic models for stability studies. This paper deals with the steady state models of TCSC [6] which can be incorporated in Newton Raphson load flow algorithm.  II. Power Flow control In its most basic form the power transmission line can be represented by a two bus system k, m. The active Innovative Systems Design and Engineering                                                                  www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online)  Vol.4, No.6, 2013 - Selected from International Conference on Recent Trends in Applied Sciences with Engineering Applications  45 power transmitted betweens bus nodes k and m is given by k mk ml| V || V |P = s in (δ - δ )X  where Vk and Vm are the voltages at the nodes, (δk-δm) the angle between the voltages and XL the line impedance. The power flow can be controlled by altering the voltages at a node, the impedance between the nodes and the angle between the end voltages. The reactive power is given by. 2k k mk ml l| V | | V | | V |Q = - c o s ( δ - δ )X X A .Thyristor Controlled Series Compensator (TCSC) The power flow model of Thyristor controlled series compensator is based on the concept of variable series reactance, the value of which is adjusted to control the power flow. The variable reactance model is represented by XT (equivalent reactance) connected in series to the transmission line between the buses k, m. The variable reactance develops a compensating voltage (reactive) which is a function of line current.      XTk kV θ∠ m mV θ∠  Fig 1.  TCSC equivalent circuit  TCSC does not exchange real power with the AC system (except for losses) [9]. It only generates or absorbs the reactive power required for compensation by the capacitor or reactor banks and the thyristor switch are used to control only the combined reactive impedance these present to the AC system.  IXcI(X-Xc)=IXTVk VmδICapacitive mode  Fig 2.  Control Mode of TCSC. The Power flow equations of TCSC can be written as k k m k m k m2k k k k k m k m k mP = V V B s in ( θ - θ )                                             ( 6 )Q = -V B - V V B c o s ( θ - θ )                            ( 7 ) where kmT1B =X, kkT1B = -X where XT is the equivalent reactance of the TCSC. In general form [10] Innovative Systems Design and Engineering                                                                  www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online)  Vol.4, No.6, 2013 - Selected from International Conference on Recent Trends in Applied Sciences with Engineering Applications  46 22P = f ( V ,θ , B )                                                                     ( 8 )Q = g ( V ,θ , B )                                                                    ( 9 )  III.Implementation Of TCSC Models In Newton Raphson Power Flow Algorithm. The TCSC power equations are combined with the network equations and linearised with respect to the state variables. The linearized power flow equations can be represented as [F(X)] = [J] [∆X] where [F(X)] is power flow mismatch vector, [J] is the Jacobian matrix; [∆X] is the state variable correction vector [1]. The device parameters are used as state variable. For the TCSC the variable reactance is taken as state variable. The inclusion of these variables increases the dimension of the jacobian.  A. Newton Raphson Power Flow Algorithm with TCSC     Innovative Systems Design and Engineering                                                                  www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online)  Vol.4, No.6, 2013 - Selected from International Conference on Recent Trends in Applied Sciences with Engineering Applications  47 B. Control Strategy For the TCSC variable series reactance is taken as the state variables. This reactance is adjusted in the Newton Raphson algorithm at each iteration automatically along with the network state variables to achieve the specified power and voltage. The variable reactance XT in the fig 3 and 4 represents the equivalent reactance of all the series connected modules making up the TCSC, when operating in either the inductive or the capacitive regions. IV. Test Case and Simulation Standard 5 bus test network is tested without TCSC and with TCSC, to investigate the behavior of the two devices in the network. In the analysis bus 1 is taken as slack bus, 2 and 3 are voltage control buses and 4, 5 are load buses. To include the TCSC in the network an additional bus (bus no 6) is introduced as shown.  For TCSC the inductive reactance is taken 0.015 pu. The TCSC is implemented as variable series reactance model for power flow control. The series reactance is taken as state variable and its value is adjusted automatically to obtain specified power which was taken as 0.19 pu.  For the TCSC the convergence was obtained at 9 iterations. The simulation yields the power flow for lines and bus active and reactive powers which are tabulated below.           Fig.4. Single line diagram of 5-Bus System. Test Data is given in Tables below TABLE I -   BUS DATA Bus no. Voltage (|v|,θ) pu Load (MW,Mvar)pu Generator Injected MVAR (MW,Mvar)pu Qmin,Qmax pu 1 1.06, 0 0  ,0 0,0 10,50 0 2 1.045, 0 20 ,10 40,30 10,50 0 3 1.03, 0 20,15 30,10 10,40 0 4 1.00, 0 50,30 0,0 0,0 0 5 1.00, 0 60,40 0,0 0,0 0  TABLE II- LINE DATA Sending Bus Receiving Bus Line resistance pu Line reactance pu Line suseptance pu 1 2 0.02 0.06 0.06 1 3 0.08 0.24 0.05 2 3 0.06 0.18 0.040 2 4 0.06 0.18 0.040 2 5 0.04 0.12 0.030 3(6) 4 0.010 0.03 0.020 4 5 0.08 0.24 0.050  1 2 3 4 5 6   TCSC Innovative Systems Design and Engineering                                                                  www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online)  Vol.4, No.6, 2013 - Selected from International Conference on Recent Trends in Applied Sciences with Engineering Applications  48 TABLE III- LINE FLOWS WITHOUT TCSC AND WITH TCSC Line No. Line Flows without TCSC Line Flows with TCSC P (MW) pu Q(MVAR) pu P(MW)  pu Q(MVAR) pu 1-2 81.3 74.02 88.6 74.2 1-3 41.8 16.8 42.4 16.7 2-3 24.5 -2.5 25.4 -2.7 2-4 27.7 1.7 26.6 -1.56 2-5 54.7 5.6 54.1 5.6 3-4 19.3 4.7 21.0 2.51 4-5 6.6 0.55 7.13 0.41  TABLE IV- BUS POWERS WITHOUT TCSC AND WITH TCSC Bus No. Bus Power without TCSC Bus Power with TCSC P(MW) pu Q(MVAR) pu P(MW) pu Q(MVAR) pu 1 131.12 90.82 131.12 90.93 2 40 -61.59 40 -61.80 3 -45 -15 -45 -15 4 -40 -5 -40 -5 5 -60 -10 -60 -10 6 131.12 90.82 131.12 90.93   V. Result and Discussion Truncated adjustment technique is used for the device to get the convergence within 10 iterations. Table III shows the change in line flows when using the TCSC. The reactive power flow in case of TCSC is reduced for all the lines as compared to base case. There is increase in active power flow in case of TCSC. It can be seen from table IV that for TCSC the power generation by the generator at bus 1 is same as the base case. A comparison of numerical values of active and reactive bus power reveals that they are nearly equal to the system without TCSC which suggest that the system voltage almost 1p.u for the buses.    VI. Conclusion The steady state models of TCSC are evaluated in Newton Raphson algorithm and the results obtained showed the possible power flow control range with TCSC.  VII. References 1. M. A Abdel Moamen and Narayana Prasad Padhy “Newton- Raphson UPFC Model for Power Flow Solution of Practical power network with Sparse Technique IEEE Intemational Conference on Electric Utility Deregulation, Restructuring and Power  Technologies (DRPT2004) April 2004 Hong Kong   1988, pp. 3-4. 2. E, Acha. V.G.Agelidis, O.Anaya-Lara, T.J.E.Miller .Power Electric Control in Electrical system Newnes Power Engineering Series. Newnes New Delhi. 3. C.R. Fuerte-Esquivel, E. Acha “Unified power flow   controller: a critical comparison, of Newton-Raphson UPFC algorithms in power flow studies “IEE Proceedings Generation Transmission. Distribution. Vol. 144, No. 5, September 1997 pg 437-443. 4. C.R. Fuerte-Esquivel, and, E. Acha ‘Incorporation of UPFC model in an optimal power flow using Newtons method’, IEE Proceeding Generation Transmission .Distribution. Vol 145, No.3 May1998,, pp336-344, 5. C.R. Fuerte-Esquivel E. Acha, H. Ambriz-Pérez, ‘A comprehensive Newton-Raphson UPFC model for Innovative Systems Design and Engineering                                                                  www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online)  Vol.4, No.6, 2013 - Selected from International Conference on Recent Trends in Applied Sciences with Engineering Applications  49 the quadratic power flow solution of practical power networks’, IEEE Trans. on Power Systems, Vol. 15, No. 1, Feb. 2000, pp. 102-109. 6. C.R. Fuerte-Esquivel and E.Acha”Newton-Raphson algorithm for the reliable solution of large power networks with embedded FACTS devices IEE Proceedings Generation. Transmission, Distribution. Vol. 143, No. 5, September 1996 pp 447-454 7. Hingorani N. G, ‘High Power Electronics and Flexible AC Transmission System’, IEEE Power Engineering Review, July 1988, pp. 3-4. 8. N. G. Hingorani ‘Flexible ac transmission’, IEEE Spectrum, Apr.1993, pp. 40-45. 9. N.G Hingorani, L. Gyugyi, ‘Understanding FACTS. Concepts and Technology of Flexible AC Transmission Systems’, IEEE Press, NewYork, 2000. 10. T.Venegas, C.R. Fuerte-Esquivel ‘Steady-state Modeling of Thyristor controlled series compensator for Phase Domain Load flow analysis of electric analysis. International conference on Power system Technology 1998, POWERCON ’98. 344-348 vol.1. 11. X e Da, Niu Hui, Chen Chen, “An Algorithm to Control the Power   Flow in Large Systems Based on TCSC”, In proceedings of International Conference on Power System Engineering, Powercon 98, Vol.1, pp. 344-348, Aug. 1998. 12. M.Noroozian, G. Anderson” Power flow control by use of controllable series components” IEEE Transactions on Power Delivery, Vol 8, No 3 July 1993.      

Evaluation of TCSC Power flow control Capability

https://www.iiste.org/Journals/index.php/ISDE/article/download/6021/6060

Evaluation of TCSC Power flow control Capability

Abstract

Similar works

Full text

Available Versions

International Institute for Science, Technology and Education (IISTE): E-Journals