Research On Strategy Of Anti-islanding Protection For Wind Farm

A lot of research has been done on photovoltaic(the "PV")power system islanding detection in recent years.As a comparison,much less attention has been paid to islanding in wind turbines.Firstly,to demonstrate the necessity of research on islanding detection method of wind turbines,this paper will analyze the electrical characteristics of output active power and reactive power,voltage and frequency of different types of wind turbines before and after the islanding.Secondly,this paper presents a new islanding detection scheme which is applicable to detect islanding in permanent magnetic synchronous generator(the "PMSG")and double fed introduction generation(the "DFIG")in single wind turbine system.In this scheme,traditional reactive power infusion method is improved and a trigger signal to avoid power deterioration is obtained by dividing voltage total harmonic distortion(the"THD")by voltage THD of last cycle.Both simulation and experiments results show the feasibility of the trigger signal.Meanwhile,the simulation results show the islanding detection scheme is effective.However,this scheme may fail in detecting islanding in wind farms due to different wind active reactive power disturbance on different parameters.As a result,this paper also simulates an islanding detection method which is more suitable for detecting islanding in wind farms by computing impedance measurement.On the one hand,the article verifies the applicability of the active impedance measurement method to detect islanding in wind farms,on the other hand,a passive impedance measurement method is proposed.