The Study Of Reliability Evaluation Method For Microgrid System

With the aggravation of energy crisis and environmental crisis in modern society,the generation of electricity by renewable energy such as wind energy and solar energy has been widely used.And with this,utilizing microgrids to make distributed generation connect to bulk power system is an effective way to exert their effects.We have reviewed every typical distributed generator,including diesel generator,wind turbine,photovoltaic and battery storage system,in order to study their reliability modeling method.Some test cases are carried out in the MATLAB environment to simulate the reliability assessment of a microgrid.Finally,the future work of reliability assessment of microgrids is discussed.Firstly,this paper introduces the common reliability indexes of microgrids,and build reliability model of different types of distributed generators,including the state space model which can be used in analytical method and the sampling model which can be used in simulation method.Based on the above work,the general process of analytical method and simulation method has been introduced,giving theoretical support to reliability assessment of microgrids.Secondly,this paper proposes a reliability assessment method of grid connected microgrids based on sequential monte carlo simulation.The method contains two different modes of microgrids,the grid connected mode and the islanded mode,and takes the randomness of renewable energy into consideration.This method provides a methodological support to reliability assessment of grid connected microgrids.Lastly,this paper proposes a reliability assessment method of islanded microgrids based on analytical approach.The method builds the multi-period probabilistic model of battery storage system,put forward a transition process of energy storage state probability distribution to describe the sequential characteristic of energy storage state,and gives new ideas to evaluate the reliability of islanded microgrids.Finally we can conclude from the MATLAB simualation that the proposed method can assess the reliability of microgrids effectively and feasibly.