提出一种应用静止同步补偿(static synchronous compensator,STATCOM)抑制次同步谐振(subsynchronous resonance,SSR)的模态互补电流控制方法。该方法采用发电机转速偏差信号作为反馈,动态生成与各模态频率互补的补偿电流信号。STATCOM实时跟踪该电流信号,向机组定子注入幅值和相位均可控的次同步和超同步补偿电流,进而在机组内部激发出与扭振模态频率一致的电磁转矩,从而对SSR起到抑制作用。从理论上推导出补偿电流与电气阻尼系数之间的定量关系,并设计控制器参数的优化方法。以某典型厂对网串联补偿输电系统为实例,通过电磁仿真验证上述机制及控制策略的有效性。通过与同背景下采用静止无功补偿器(static var compensator,svc)抑制SSR方案的比较分析,表明基于上述方法的STATCOM抑制SSR的方案具有一定的技术/经济优越性。
This paper proposes a static synchronous compensator-subsynchronous resonance (STATCOM-SSR) damping control method based on dynamic compensation of currents at complementary frequencies to torsional modes. The method uses generator speed deviation as the feedback and produces reference currents corresponding to torsional modes. The STATCOM traces the reference signals so as to inject controllable sub- and super-synchronous currents into generator stators. Consequently electromagnetic torques at torsional frequencies are developed to damp SSR. The relationship between the compensative currents and the resulted electrical damping coefficients was derived mathematically. And the control parameters were optimized simultaneously. The proposed control scheme was tested on a typical series-compensated transmission system on simulation. The results demonstrated its effectiveness in damping multimodal SSR. A comparison was also made between STATCOM- and static var compensator (SVC)- based scheme, which indicates that STATCOM gains numbers of advantages over SVC.