连接不平衡电网的链式静止同步补偿器控制方法及动态特性研究

Research on Control Scheme and Dynamic Characteristic of Cascaded STATCOM with Connected to Unbalanced Grid

研究连接不平衡电网的链式静止同步补偿器(STATCOM)的控制方法和动态特性。首先研究链式STATCOM的拓扑结构和控制策略,提出基于有功功率微调的子模块直流电压均衡控制方法。其次,对链式STATCOM的稳态运行工况进行时域仿真和FFT分析,发现谐波畸变率和子模块电压均衡效果均满足要求。最后,分析不同锁相环参数、不同直流电压控制参数以及不同无功功率输出工况下的链式STATCOM小干扰动态特性。结果表明,适当提高直流电压环带宽和适中设置锁相环带宽,有利于提高链式STATCOM系统的动态特性。

In this paper,the control method and dynamic characteristics of cascaded Static Synchronous Compensator(STATCOM)connected to unbalanced grid are studied.To begin with,the topology and control strategy of cascaded STATCOM are investigated,and a submodule DC voltage equalization control based on active power small tuning is proposed.On this basis,the time-domain simulation and FFT analysis of the steady-state operation of cascaded STATCOM are carried out,finding that the harmonic distortion rate and the DC voltage equalization of the submodules both meet the requirements.Finally,the dynamic characteristics of cascaded STATCOM are analyzed with varied phase-locked loop(PLL)parameters,varied dc voltage control parameters and varied different reactive power output conditions,and the results show that it is beneficial to improve the dynamic characteristics of cascaded STATCOM system by appropriately increasing the dc voltage loop bandwidth and moderately setting the PLL bandwidth.