链式STATCOM在电网电压不平衡时的正负序协调控制方法

摘要

When there is an unbalance in power grid voltage,the control strategy for balanced system makes STATCOM output positive sequence voltage.In this case,the negative sequence component in the voltage makes device stop functioning due to overcurrent.In the light of the overcurrent in cascaded STATCOM under the unbalanced voltage condition,the phase information is obtained by the advanced open-loop phase synchronization scheme to separate the phase sequence of the output voltage of the device and the grid voltage,and the positive and negative sequence components in the output voltage of the cascaded STATCOM is separated.Based on the control of the positive and negative sequence components and analysis from the view of power balance,this paper gets the relationship between phase-shift angle and modulation ratio for the coordination control of the positive and negative sequence components,and proposes the coordination control of the positive and negative sequence components in the cascaded STATCOM under the unbalanced voltage condition.The simulation results show that the proposed method is correct and effective.%当电网电压不平衡时,针对平衡系统设计的控制策略将使STATCOM输出正序电压,电网电压中的负序分量可能会造成装置过流而退出运行.围绕链式STATCOM在电网电压不平衡工况下的过流问题,利用先进的电网相位开环同步控制方法来应对电网电压相位的扰动,实现了对装置输出电压以及电网电压的相序分离,实现了对链式STATCOM输出电压的正负序分离与协调控制,通过将装置分解为正序和负序两部分控制,并且从功率平衡的角度分析,得到了正负序协调控制所需满足的相移角、调制比两方面的关系,提出了完整的链式STATCOM在电网电压不平衡时的正负序协调控制方法.仿真实验结果证明了该控制方法的正确性、有效性.