主动移频式孤岛检测法产生稀释效应机理的分析

Analysis of dilution phenomenon for active frequency shift islanding detection method

由于分布式发电系统的孤岛效应会造成多种有害影响,基于并网逆变器的分布式发电系统要求具备孤岛检测功能。主动移频式孤岛检测法是常用的检测孤岛的方法。介绍了几种主动移频式孤岛检测法的工作原理及其在多逆变器并联运行条件下的孤岛检测性能。分析了主动移频式孤岛检测法产生稀释效应的机理并进行了仿真验证。仿真的结果表明,Sandia频率偏移法在多逆变器并联运行时可能会因为稀释效应导致孤岛检测失败,而滑模频率偏移法受稀释效应的影响不大。

Because islanding phenomenon of distributed generator will give rise to a variety of harmful effects, the function of islanding detection is required for the grid-connected inverter-based distributed generator. Active frequency shift method is the commonly used islanding detection method. The paper introduces the principles of this method and the detection performance under multi-inverter parallel operation condition, analyzes the mechanism of dilution phenomenon for active frequency shift islanding detection method and verifies the conclusions using Matlab simulation. Simulation results show that the SFS islanding detection method may have dilution phenomenon and result in aborted detection under multi-inverter parallel operation condition, while the SMS islanding detection method is almost unaffected by the dilution phenomenon.