SVC&TCSC的原理及应用

Chapter23

Improvement of system stability margins

using coordination control of Static Var Compensator(SVC)and Thyristor

Controlled Series Capacitor(TCSC)

Venu Yarlagadda,K.R.M.Rao and B.V.Sankar Ram

Abstract The Thyristor Controlled Series Compensator(TCSC)and Static Var Compensator(SVC)are variable impedance Flexible AC Transmission Systems (FACTS)Controllers.A combination of the TCSC and the SVC installation is proposed to acquire superior performance for the power system.The coordination between the two pieces of equipment is designed with the SVC treated as the supplement of the TCSC.When operation of the TCSC is constrained by the inherent limitation of equipment,such as due to thefiring-angle limitation of the thyristors,the adjustable SVC can supply the auxiliary support to improve the overall performance.The voltage and angle stability margins can be greatly improved with the compatible control schemes of the TCSC and the SVC. Keywords TCSCÁSVCÁCo-ordination control of SVC and TCSCÁDesign of small scale TCSC modelÁVariable impedance FACTS controllersÁSingle machine two bus systemÁVoltage stabilityÁP–V curves and P-d curves

V.Yarlagadda(&)

EEE Department,VNR VJIET,Hyderabad,India

e-mail:venuyar@

K.R.M.Rao

EEE Department,MJCET,Hyderabad,India

B.V.Sankar Ram

EEE Department,JNTUH,Hyderabad,India

207 V.V.Das(ed.),Proceedings of the Third International Conference on Trends in Information, Telecommunication and Computing,Lecture Notes in Electrical Engineering150,

DOI:10.1007/978-1-4614-3363-7_23,ÓSpringer Science+Business Media New York2013

208V.Yarlagadda et al.

23.1Introduction

Voltage stability improvement demands different techniques,fixed compensation and the variable compensation.FACTS controllers which are the variable com-pensation devices are being used for more effective results.In this paper,the coordination control of Thyristor Controlled Series Capacitor(TCSC)and Static Var Compensator(SVC)is implemented practically in the laboratory.The TCSC is used as an auxiliary controller and SVC is used as the Master controller by which the Stability Margins have been enhanced tremendously which has been proved by the P–V and P-d curves and bar charts.

23.2Power System Stability

Successful operation of a power system depends largely on the engineer’s ability to provide reliable and uninterrupted service to the loads.The reliability of the power supply implies much more than merely being available.

Ideally,the loads must be fed at constant voltage and frequency at all times.In practical terms this means that both voltage and frequency must be held within close tolerances so that the consumers’equipment may operate satisfactorily. 23.3Stability Indices

23.3.1P-V Curve

As the power transfer increases,the voltage at the receiving end decreases.Finally, the critical or nose point is reached.It is the point at which the system reactive power is out of use.The curve between the variation of bus voltages with output power(P)is called as P–V curve or‘Nose’curve.PV curves are used to determine the loading margin of the power system.The margin between the voltage collapse point and the current operating point is used as voltage stability criterion. 23.3.2P-d Curve

The relation between input power and the load angle is called power angle characteristics.The equation is given by,P=EVsin d/X.The steady state stability limit is EV/X and it occurs at90°.