| In recent years, the technology of distributed generation in solar, wind andfuel cell as the main energy has been widely used in the world and will become animportant direction of future development of electric power industry,due to therapid development of power industry and the increasingly serious problem ofenvironmental pollution. Distributed generation has many advantages to reduceenergy consumption, reduce pollution, save investment, and improve the reliabilityand flexibility of power system. However, there are still many problems need to besolved in order to ensure the reliable operation of power grid when distributedgeneration is in grid-connected operation.The islanding problem is one of the basicproblems in thedistributed generation systems.Detecting the islanding effect timelyand effectively has important significance to guarantee the safe and stableoperation of the system.At present, domestic and foreign scholars have proposed a lot kind ofislanding detection methods. According to the characteristics of these methods,they can be roughly divided into passive anti-islanding strategies and activeanti-islanding strategies. The passive anti-islanding strategies often have largerNon-Detection Zone(NDZ), the active anti-islanding strategy can greatly reduce theNDZ, however itwill influent the stability of the system and the quality of powersupply because of the introduction of disturbance.This paper focuses on the study of islanding detection methods based on theimpedance detection, accordingto the point of common coupling (PCC) before andafter the change of impedance magnitude of islanding detection. The method isactive detection. Moreover, this method does not present NDZ and only a smallimpact on the quality of electric energy. At last, it validates the accuracy andreliability of the method through simulation and experiment. |
