一种适用于弱电网的混合式孤岛检测方法

A Hybrid Island Detection Method Suitable for Weak Power Grid

对于并网逆变器存在的孤岛效应问题,此处提出了一种适用于弱电网的混合式孤岛检测方法。首先,基于分布式发电系统进行分析,采用被动法与主动法结合的混合式孤岛检测方法,其中被动法采用电压不平衡法与频率变化率法,主动法采用无功功率扰动法。主动法仅在被动法怀疑发生孤岛时启动,以避免因主动法导致的电能质量下降。其次,此处采用的电压不平衡法,通过理论推导和实验验证可适用于弱电网下的孤岛检测,同时对传统的无功功率变化方法进行改进,添加基于频率的正反馈,实现快速、低谐波的孤岛检测。

A hybrid islanding detection method is proposed which is suitable for weak power grids to address the issue of islanding effects in grid connected inverters.Firstly,based on the analysis of distributed generation systems,a hybrid island detection method combining passive and active methods is adopted.The passive method adopts voltage imbalance method and frequency change rate method while the active method adopts reactive power disturbance method.The active method is only activated when the passive method suspects islanding,in order to avoid a decrease in power quality caused by the active method.Secondly,the voltage imbalance method used can be applied to island detection in weak power grid through theoretical derivation and experimental verification.At the same time,the traditional reactive power change method is improved by adding frequency based positive feedback to achieve fast and low harmonic island detection.