The Reliability Evaluation Of Islanded Microgrid Considering The Operational Failure Of Converter And Energy Storage System

With the increasing problems of energy crisis and environmental pollution,distributed power generation technology based on renewable energy has become the focus of research in countries around the world.As a controllable unit,the islanded micro-grid can integrate and utilize all kinds of distributed energy sources to achieve local consumption and solve the problem of long-distance transmission.In view of the characteristics of renewable energy output and the introduction of power electronic devices,new problems arise in the reliability evaluation of islanded micro-grid.It is difficult to comprehensively evaluate the reliability of the micro-grid by the traditional reliability assessment method.Based on this,this paper studies the related issues of reliability evaluation of island micro-grid.The main contents are as follows:(1)Establishing operational failure rate model of power electronics and converter.Considering the operational condition of the micro-sources converter,the failure mechanism of the power electronic device is analyzed,and operational failure rate model of power electronics and converter are established by combining the loss model and the thermal model.The reliability analysis of the micro-source converter is carried out taking into account the operational conditions.The results show that the failure rate of the micro-power converter changes in real time,and is affected by the operational condition,converter parameters and parameters of microsource.This operational failure rate model can better reflect the multiple factors in the micro-grid for power electronic devices and converter.(2)Based on the traditional islanded micro-grid reliability evaluation algorithm,a reliability evaluation algorithm considering the operational failure rate of the converter is proposed.Based on the operational state and condition of the micro-grid,the grid structure of the micro-grid is considered.The load reduction strategy combines the micro-grid reliability assessment algorithm with the short-term outage model to analyze the reliability of the WTG/PV/ESS islanded micro-grid.Finally,the reliability sensitivity factor test is performed for the islanded micro-grid system.The results show that the operational failure of the converter has a negative impact on the reliability of the microgrid.The reliability evaluation results of the traditional microgrid are often optimistic.(3)Based on the above research,taking into account the reliability of the energystorage system and its operating strategy,hybrid energy storage system is introduced,studying the impact of the energy storage system category and operating strategy on the reliability of the micro-grid,and considering the operational failure rate of the power electronic device to do the quantitative reliability evaluation of the WTG/PV/DG/ESS islanded system.Analyzing the impact of operational parameters of the energy storage system and the configuration of the micro-sources power supply capacity on the reliability of the micro-grid,and provide suggestions for the reliability improvement of the micro-grid.The results show that the reliability of micro-grid is different under different energy storage system types and operating strategies.The algorithm used in this paper can evaluate the reliability of micro-grid more comprehensively and accurately than traditional algorithms.