基于非特征谐波正反馈的微电网变流器孤岛检测方法

微电网变流器在微电网系统并网和孤岛工况下需要采取不同的控制策略,在不依赖外部通信的基础上,微电网变流器必须能够自主实现对微电网系统状态的判断。基于电压正反馈的孤岛检测思想,结合微电网变流器实际运行环境,提出采用非特征谐波正反馈与传统过欠压、过欠频等被动检测方法相结合的方式来实现对微电网系统状态的判断。文中分析了正反馈的工作原理、系数取值和非特征谐波的测量方式,并通过仿真和实验研究验证了该方法的可行性。研究结果表明,所提出的孤岛检测方法在多种复杂工况下均可实现对微电网系统状态的准确判断,有利于微电网系统由并网向孤岛模式的平滑切换。

An Islanding Detection Method for Microgrid Converters Based on Positive Feedback of Uncharacteristic Harmonics

The control strategies for microgrid converters in grid-connected mode and islanding mode are different. Without reliance on rapid communication, micro-grid converters must be able to distinguish the states of the microgrid system on their own. In consideration of the practical operation environment, a new composite islanding detection method combining positive feedback of uncharacteristic harmonics and passive islanding detection is proposed for microgrid converters based on the islanding detection idea of voltage positive feedback. The principle, coefficient values and measurement mode of positive feedback are analyzed, and the feasibility of the method proposed is verified by simulation and experimental study. The simulation and experiment results show that the proposed method can detect islanding quickly and accurately in complicated working environments. What is more, it is conducive to smooth changeover for microgrid converter control strategy.