| With the daily consumption of global energy,fossil energy is almost exhausted and polluted seriously,so it is urgent to develop and utilize clean energy.At present,photovoltaic and wind power generation technology is mature,installed capacity is large,has become the mainstream distributed generation system.Distributed system access to power grid has many advantages,but the isolated island phenomenon may damage the power equipment and pose a threat to the safety of power maintenance personnel.Therefore,the study of islanding detection method has practical significance.Firstly,the mathematical model of photovoltaic cell and wind power generation is established,and the simulation model of photovoltaic and wind power generation system is built in Matlab environment,and the corresponding characteristic curve is obtained.At the same time,the model of photovoltaic and wind power hybrid generation system is established,which lays a foundation for the analysis of subsequent islanding detection.Secondly,the islanding effect conditions of the distributed grid-connected power generation system are analyzed,and the concept of non-detection zone is introduced to evaluate the effectiveness of the detection method.This article introduced the detection standards,power grid terminal detection and passive detection of islanding detection.The active frequency drift detection methods,including active frequency drift method and active frequency drift method with positive feedback are studied,and the parameters affecting the non-detection zone distribution are analyzed.Finally,aiming at the dilution effect of multi-inverter,an active frequency drift islanding detection method based on frequency change rate is proposed.This method could detect the conventional islanding effect of distributed grid-connected power generation system and overcome the dilution effect caused by parallel multi-inverter.The effectiveness of the method is verified by simulation results. |
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