Dynamic reactive power compensator is typical thyristor switched capacitor (TSC), and thyristor -controlled reactor (TCR). Practical applications, the TCR used in conjunction with a shunt capacitor , depending on the element switched capacitor can be divided into static and fixed capacitors used in conjunction with TCR reactive power compensator, and TCR with switched capacitor circuit breakers used in conjunction with the compensator, and reactive power compensator TCR used in conjunction with TSC . The important feature is the combination of the SVC can continuously adjusting the reactive power compensation device , dynamic compensation , the compensation voltage at the point that nearly unchanged , but only SVC voltage compensation system , the compensation of reactive power output point node is proportional to the square of the voltage , when the voltage reduces the compensation effect will be weakened . The main role of SVC voltage control , the use of appropriate control methods , SVC can have power oscillation damping system and increase stability and so on. Currently , SVC technology is relatively mature, foreign from the 1960s have begun to use SVC, the late seventies for voltage control of the transmission system , after decades of development, not only the dynamic reactive power compensator for transmission system voltage control , but also for compensation and control the distribution system , but also for electricity end users a voltage controlled reactive power compensation.