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针对被动孤岛检测存在检测盲区以及传统主动频率偏移(AFD)孤岛检测算法会带来有功电流波动的不足,提出一种改进的AFD孤岛检测算法。该算法通过控制无功电流的大小来实现电流频率偏移,从而实现孤岛状态下接入点电压频率的正反馈,进而检测出孤岛。为了减小无功电流对电力系统的污染,需将该AFD算法与传统的被动孤岛检测算法结合使用。仿真和实验结果表明,该孤岛检测算法不仅消除了被动孤岛检测算法在负载功率和逆变器功率匹配时存在的检测盲区,而且克服了传统AFD算法有功电流波动的缺点,提高了直流母线电压的稳定性。
In order to overcome the shortcomings of the active current fluctuation caused by the detection blind spot and the traditional active frequency offset (ISD) island detection algorithm, a new algorithm of islanding detection based on AFD is proposed. The algorithm realizes the current frequency offset by controlling the size of the reactive current so as to realize the positive feedback of the voltage and frequency of the access point in the island state and then detect the isolated island. In order to reduce the pollution of reactive power on the power system, the AFD algorithm needs to be combined with the traditional passive islanding algorithm. The simulation and experimental results show that the island detection algorithm not only eliminates the detection blind zone of the passive island detection algorithm when the load power and the inverter power match, but also overcomes the shortcoming of the active current fluctuations of the traditional AFD algorithm and improves the DC bus voltage stability.