弱网系统STATCOM直流偏磁问题试验研究

Experimental Study on Direct Current Bias Problem of STATCOM in a Weak Network System

链式静止同步补偿器(STATCOM)在工程应用中存在低次谐波含量严重超标的现象,针对该问题进行理论研究和建模分析,研究发现STATCOM连接于弱电网会引发稳定性问题,引入直流分量的正反馈,直流电流注入并网变压器会造成变压器偏磁,导致并网电流中存在大量低次谐波。为了解决该问题,提出了在控制策略中引入电流隔直控制环,可有效抑制STATCOM并网电流的直流分量。最后,基于上述理论研究分析,在实际工程应用中加入了上述电流隔直控制环,试验结果表明了所提控制策略的正确性。

Static synchronous compensator（STATCOM） has been found to be a serious problem with abundant low-order harmonics in the engineering application.The problem of stability of STATCOM connected to the weak grid is studied which introducts the positive feedback of direct current component, direct current into the grid transformer will cause the transformer bias resulting in a large number of low-order harmonics in the grid current.In order to solve this problem, the idea of introducing direct current isolation control loop in the control strategy is put forward which can effectively suppress the direct current component of the STATCOM grid-connected current.Finally, based on the above theoretical research and analysis, the direct current isolation control loop is added to the actual project.Experimental results show that the proposed control strategy is correct.