不平衡电压和闪变下静止无功发生器的鲁棒稳定性研究

Research on Robust Stability for SVG Under the Unbalance Voltage and Flicker Conditions

针对三相四线制三桥臂双电容式SVG补偿精度问题,对其模型进行分析。提出了一种自适应性加强型锁相环(enhanced phase-lockloop,简称EPLL),其相位跟踪不受电压不平衡和闪变的影响,鲁棒性好,精度高。针对传统LCL滤波器存在的谐振峰,功率损耗大和滤波效率低等缺点,设计一种RC串联的LCL滤波方法应用于三相四线制三桥臂双电容式SVG。通过建立基于RC串联的LCL的系统模型,构建系统传递函数并利用系统传函等效原则,设计滤波参数。仿真与实验表明:RC串联的LCL滤波器能够较好地抑制开关频率谐波,且高频纹波抑制效果好;自适应性加强型锁相环,可以在保证响应速度的同时提高电流跟踪精度。

Aiming at the problem of three-bridge-arm double capacitive SVG compensation accuracy in three-phase four-wire system, its model is analysed. A self adaptive enhanced phase-lock-loop （EPLL） is suggested in which the phase follow is not affected by the unbalance voltage and is of good Robust stability and high accuracy. In or- der to overcome the shortcomings of resonance peak, high power loss and lower filtering efficiency in traditional LCL filter, a LCL filtering method with RC in series is designed to be applied in the three-bridge-arm double ca- pacitive SVG in three-phase four-wire system. Based on such model, the system transfer function is built up and then the filtering parameters are designed. The simulation and experimental results show that this model can effec- tively restrain the harmonic with switch frequency and with good restrain effects to high frequency ripples. EPLL can guarantee the response speed and increase the current following accuracy.