电网电压不对称对D-STATCOM的影响分析及抑制

摘要

Under unbalanced voltage of power system, the influence on voltage output performance of distribution network static synchronous compensator (D-STATCOM) is analyzed. Two times frequency wave occurs in voltage of capacitor at DC side of D-STATCOM under unbalanced voltage, which result in negative sequence and 3 times harmonics in AC voltage and converter may be overcurrent caused by negative sequence current and 3 times harmonic current. According the problem above, improved switching function modulation is proposed to improve voltage output performance of D-STATCOM and suppress 3 times harmonic current. An unbalanced control strategy of feed-forward control for negative sequence voltage is also carried out to suppress converter overcurrent caused by negative voltage in order to make D-STATCOM safe. Simulation results show the good performance.%分析了电网电压不对称对配电网静止同步补偿器(D-STATCOM)电压输出性能的影响,指出电网电压不对称将导致D-STATCOM直流侧电容电压出现2倍频波动,使得交流输出电压出现负序和三次谐波,严重影响D-STATCOM输出性能,并且由此产生的负序和3次谐波电流将造成装置过流.针对此问题,提出一种改进开关函数调制法,抑制了3次谐波电流,改善了D-STATCOM的电压输出性能.提出一种负序电压前馈控制的不对称控制策略,抑制了D-STATCOM因负序电压分量造成的过流,保障了装置的安全可靠运行.仿真实验结果表明,本文提出的方法是行之有效的.