Application of Controllable Reactors in China’s Power Grid at Extra and Ultra Voltage Level

Abstract

Because of the relatively high charging capacitance of Ultra High Voltage transmission lines, the contradiction between UHV transmission line’s over-voltage limitation strategy and its reactive power compensation strategy becomes prominent, while fix controllable reactors on UHV lines whose load is heavy or changing greatly may be an effective way to solve this contradiction. Through analyzing the typical system’s characteristic and UHV transmission line’s characteristic, the strategy by controllable reactor is presented in this paper. Authors also point out that the controllable reactor’s application in UHV network should be tested on existing 500kV system first, which will be helpful for the implementation of controllable reactor’s on UHV network in future. This study shows that the effect on transient stability by controllable reactors depend on their capacity in steady operation, while for dynamic stability, mode of control is more important than capacity in steady operation. The controllable reactors, which regulate smoothly without delay or switch step by step act best, of cause their rating capacity are all put into operation in steady state.