| In recent years,distributed generation technology developed from renewable energy sources has been widely used worldwide.It has the advantages of economical investment,flexible power generation,clean and environmental protection.At the same time,the deep integration of new technology and new energy industry makes the micro-grid formed by distributed generation more mature and stable.China has made great achievements in the power flow calculation method for large power grids,but the power flow calculation method for micro-grids operating in isolated mode can not be ignored.This paper firstly introduces the research status of microgrid and its power flow calculation at home and abroad,and explains the necessity of studying power flow calculation of isolated microgrid.Three control modes of micro-power supply in micro-grid are studied: PQ control mode,V/F control and droop control,and their respective controllers.The correctness of the MATLAB simulation model is verifiedSeveral classical power flow calculation methods for isolated island microgrid are selected and analyzed and compared.The convergence speed and calculation speed of each power flow calculation method are summarized.Based on the traditional Newton-Raphson method for power flow calculation,an improved initial value method for power flow calculation is proposed and simulated.A micro-grid system which can control power flow state by switching loads is designed,and its control process and feasibility are analyzed. |
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