Modeling And Simulation Of Controlled Reactor Used For Extra-High Voltage Grid

Power system reactive power compensation and reactive power balance can improve the stability of transmission system,transmission capacity and inhibit the over-voltage. Controllable reactor,as a common FACTS equipment, has wide range of uses in reactive power regulation,power stability and power load characteristics improvement. This paper analyzes the UHV AC transmission system over-voltage principle, influence of System parameters for high-voltage transmission line to power frequence over-voltage,reactive compensation and adjustment range of controllable reactor, introduced the basic structure and working principle of SCSR(Step Controllable Shunt Reactor). The simulation model of SCSR is established in PSCAD/EMTDC based on this basis.Steady-state electrical characteristics and transient electrical characteristics of SCSR are analyzed through simulation, the simulation results indicate each capacity of SCSR can accurately switching, phenomenon of capacity superposition state and dc current component can be eliminated, the simulation model is valid and effective; protection scheme of primary protection,secondary protection of reactor and neutral reactor are determined protection configuration and the principle of the protection are determined,after an comprehensive analysis of all possible type of faults that may occur; for the problem of low sensitivity of turn-to-turn protection, a simulation of zero-sequence power directional protection and negative-sequence power directional protection used in turn-to-turn fault and internal ground short circuit, simulation results show that both zero-sequence power directional protection and negative-sequence power directional protection should be adopted in order to improve the sensitivity and reliability of turn-to-turn protection.