不对称故障下STATCOM的运行和控制

Operation and Control on the STATCOM During Asymmetrical Faults

随着电网负荷日益复杂化,电网常出现不对称故障,而且传统静止同步补偿器(STATCOM)存在参数整定难,计算复杂的缺点,故不能很好地实现无功电流的实时补偿和装置的稳定运行。通过对不对称故障状态下逆变器直流侧电压失稳机理的分析,提出一种基于正负序矢量分别定向控制新策略。该控制策略对不对称电压电流进行矢量分解,并在正负序网络下对各电矢量分别进行定向控制,从而可以有效抑制输出谐波分量,稳定直流电压,并实现动态无功补偿。同时结合能量泄放装置实现STATCOM在故障下的不脱网运行。该控制策略简单可靠,具有高鲁棒性,易于实现;仿真和实验结果表明,采用提出的控制方法可以及时穿越不对称故障,并有效补偿系统无功,稳定直流侧电压。

Traditional control strategy has difficult parameters adjusting and complex calculation under power faults for the increasing complexity of grid load. Static Synchronous compensator had been difficult to achieve good real-time reactive current compensation and devices＇ stable operation. Based on the analysis of DC voltage instability in the condition of the asymmetric fault, the paper presented a new strategy which respectively orientates positive and negative sequence vector. The strategy would implement vector decomposition for asymmetric voltage and current to realize control scheme-oriented of electric vectors respectively in positive and negative sequence net-work, which could effectively suppress output harmonics, stabilize DC voltage, and realize dynamic reactive power compensation. Furthermore, Energy discharge devices were introduced to improve STATCOM which did not run off the network when there were some faults. The new strategy is simple and reliable, high robustness, easy to implement. Simulation results show that the proposed control method can go through the faults in time, compensate reactive power effectively and stabilize the DC side voltage.