链式STATCOM直流电压预测与专家控制

DC voltage prediction and expert control of cascaded STATCOM

从功率平衡的角度分析了链式STATCOM直流侧电容电压波动,建立电容电压波动模型,基于该模型提出了一种积分复位预测方法,可准确预测直流侧电容电压波动.将电压波动预测结果从电容电压检测值中分离,得到电容电压的直流分量进行反馈控制,有效降低了有功电流指令中的三倍频谐波分量.为改善无功突变时系统的动态性能,对电压波动预测结果进行限幅,引入专家PI控制进行电容电压调节.在Powersim仿真环境下搭建了链式STATCOM仿真模型,验证了所提电压波动预测方法的准确性,对比了专家PI控制与传统PI控制的仿真结果,验证了所提控制方法对暂态电容过电压的抑制效果.

In view of power balance,the DC(direct current)voltage fluctuation of cascade STATCOM(static synchronous compensator)was analyzed and a voltage fluctuation model was established.Based on the model,an integral reset prediction method was proposed to predict the DC voltage fluctuation accurately.By subtracting the fluctuation part from the predict voltage and adopting the DC part of capacitor voltage,voltage feedback control could reduce the third harmonic of active current instruction effectively.To improve the dynamic performance of system obviously when reactive power abrupt changed,the voltage fluctuation predict value was limited and an expert PI(Proportional-Integral)control was used to regulate the capacitor voltage.The validity of the proposed voltage fluctuation prediction method was verified by the simulation result generated from the cascade STATCOM simulation platform in Powersim.Compared to traditional PI control method,the proposed expert PI control shows superior overvoltage suppression effect.