Transient characteristics and optimal control strategy of superconducting controllable reactor

Superconducting controllable reactor (SCR) is a promising device for reactive power compensation to improve the voltage stability and reliability of power system. Given the special structure and complex magnetic circuit of SCR, the transient characteristics and control strategy, which have an important effect on the performance of SCR, lack comprehensive analysis. In this study, transient characteristics analysis and an optimal control strategy are proposed. First, the basic operating principle and the impedance of the analytical model of SCR were presented. Second, the transient characteristics on the DC component and the overvoltage of SCR were analyzed in detail, and an optimal control strategy based on circuit breaker and anti-parallel thyristors was proposed. Finally, the principle and performance of proposed methods were validated through electromagnetic simulation and experiments of 380V/30kVar prototype. The simulation and experimental results demonstrate that the DC component and overvoltage will be produced in the transient process. When the switching angle of superconducting winding is 90 degrees, the DC component and overvoltage become small. The optimal control system proposed can avoid producing the DC component and overvoltage that damage the superconducting windings. The results obtained in this study can be applied to the optimal performance design of SCR.