Ron Distributed Generation Iding Detection Method

As fossil fuel COsts continue to rise and the increased awareness ofenvironmentalprotection,the distributed energy generation technology of renewable energy as themain raw material has been widely used in countries around the world．Distributedgeneration call be effective and rational use of energy,reduce network losses andinvestment costs．ARer the power blackout in large system,distributed power Can stillbe a continuous power supply to the local load and improve power system stabilityand flexibility．However,distributed generation to the power system in the enormouseconomic benefits,it also faces many problems．Among them,how to transform thedistributed generation system from network state to islanding state safely andsmoothly is a serious problem．Therefore,the islanding detection technique indistributed power generation grid connected system has important researchsignificance．Existing islanding detection scheme is classified into passive detection and activeone．Passive detection method has a large blind spot,a longer detection time．Thismethod requires a combination of active detection methods in practical application．Although the blind spot of the active detection method is relatively small,but thescheme has a great impact onpower quality,and the sensitivity is not enough．For theabove shortcomings,the combined algorithm of negative sequence voltage positivefeedback and the voltage-active power positive feedback has been proposed in thispaper．In this method,the introduction of frequency variation to voltage - activepower positive feedback improves effectively the detection efficiency and shortensthe detection time．In the case of power mismatch,the method Can pick out the stateof island quickly and reliably through negative sequence voltage positive feedback．Inthe case of power matching,the module of negative sequence voltage positivefeedback makes a early warning signal because of negative sequence voltage occurredduring the switching process between network state and islanding state．Thew arningsignals Can disturb the active power,SO voltage-active power positive feedback starts．This Can effectively and reliably detect the event of island．A 3kW power supply andnetwork system of distributed simulation model of island has been built by MATLAB/SIMULINK software．Islanding detection principle proposed is simulated in the model．Simulation results show that:the proposed islanding detection method iscorrect,sensitive and reliable．...