基于负序电流注入的光伏并网逆变器孤岛检测方法

摘要

The photovoltaic power source would keep supplying power under unscheduled islanding operation, and hence bring potential risk for maintenance personnel and electric equipments, so it is of great significance to enforce accurate and rapid islanding detection method. A method based on negative sequence current injection and voltage imbalance on the point of common coupling is proposed. The reasonable switching strategy of negative sequence current in the grid-connected inverter reduces the impact of injected current on the main power grid. The method, without non-detection zone, is also unaffected by asymmetric faults of the power grid. Case study shows that the method could detect islanding state accurately and quickly under the worst condition while the power of the PV matches the load power, and the voltage and the frequency of the PCC has small shift.%孤岛运行时光伏电源继续向负载供电，会给检修人员和用户设备带来安全隐患，快速有效地实现孤岛检测具有重要意义。提出了一种通过并网逆变器注入负序电流并检测公共连接点电压不平衡度的快速孤岛检测方法。通过合理投切负序电流注入降低了对电网的干扰，不受电网不对称故障的影响且无检测盲区。在光伏电源功率与负荷功率匹配、公共连接点电压和频率基本不发生偏移的情况下对该方法进行了仿真验证，结果表明即便在这种最不利于孤岛检测的情况下，该方法仍能快速准确地检测出孤岛运行状态。