摘要：Nowadays renewable energy sources are used by most of the distributed generations. Because oftheir blessings like clean nature, pollution free, cost free the utilization of them are increasingin life style. The key drawback of such distributed generation is associated with unintentionalislanding development. Islanding will causes in the distributed generation due to unintentionalopening of main grid. Islanding will causes dangerous conditions to equipments and apparatusconnected with it. Thus, it is needed that as per IEEE 1547 and UL 1741 standards within 2seconds we have to detect the islanding. In this paper a new hybrid islanding detection methodis presented with low frequency current harmonic injection and over/ under frequency relay forinverter based distributed generation. A low frequency current harmonic is injected into thesystem through the q controller of the grid side controller. The injected low frequency currentcomponent causes the system frequency to deviate during islanding. This paper evaluates theperformance of this hybrid ROCOF relay when load and generation are matched andsuccessfully detecting the islanding. This paper will also clearly differentiate between islandingand non islanding events for mixed types of DGs connected to the grid. The test system results,are carried out in MAT LAB/Simulink environment shows the strength of this method.
关键词：Islanding detection; Low frequency current harmonic injection; Rate of change of;frequency (ROCOF) analysis; Distributed Generation (DG); Non Detection Zone (NDZ).
