低频电源注入式主动孤岛检测方案

摘要

用户侧并网的分布式电源发生孤岛运行的可能性较大,从用电安全和电能质量考虑,必须快速、准确地检测出孤岛.提出一种外加20 Hz低频电源注入式主动孤岛检测方案,把相当于零序分量的20 Hz分量注入380 V系统,根据孤岛发生前后20 Hz分量的变化特征识别孤岛.对方案的构成、检测原理、参数设计及对电能质量的影响进行详细描述和分析,并用MATLAB进行建模仿真,验证了分析结果的正确性.根据分析结果提出基于绝对值幅值比较原理的孤岛识别判据,并在分布式电源并网接口装置中进行了实现.最后,在某小型屋顶分布式光伏发电系统中进行了实验验证.%The probability of islanding of grid-connected distributed generators is relatively large on the user side.Taking the user safety and power quality into account,the islanding mode should be detected quickly and accurately.An active islanding detection scheme based on 20 Hz low-frequency power supply injection is proposed.The 20 Hz component which is equivalent to zero sequence component is injected into the 380 V system and islanding is identified by the change characteristics of the 20 Hz component.The composition and detection principle of the proposed scheme,parameters selection and its influence on power quality are described and analyzed in detail.MATLAB is applied in the modeling and simulation,and correctness of the analysis is verified by simulation results.The identification criterion for the island mode based on comparison of the absolute value is proposed and realized in a grid-connected interface device.Finally,the scheme is experimentally verified in a small rooftop distributed photovoltaic generation project.