Research Of Control Strategies For Inverters In Microgrids Based On Virtual Synchronous Generator

In recent years,with the increasing exhaustion of traditional energy sources and the rapid growth of power demand,it suddenly rises that the distributed generation of the renewable energy is used as an effective complement to the centralized power generation.Microgrids,which is the one of the most effective ways to use distributed generation,have become the hot topics in the study of experts and scholars at home and abroad.In this paper,research object is the microgrids' inverter control strategy,and this paper mainly analyzed virtual synchronous generator.This dissertation is organized as follows:This paper introduces the research background,summarizes the definition,characteristics and structure of microgrids,and points out that the inverter plays an important role in the microgrids.Then this paper discusses in detail the three control methods about inverters,namely the constant power control,the constant voltage and constant frequency control and droop control.And it analyzes and compares those control characteristics and application scope.Virtual synchronous generator inverter control mainly imitate the traditional synchronous generator operation,this paper established the corresponding mathematical model of the synchronous generator,the active power-frequency controller and the reactive power-voltage controller were designed and optimization.At the same time,this paper proposes a modified virtual synchronous generator whose parameters are variable,and this advanced control strategy can effectively improve the output response speed and make the inverter become rapid and stable.Seamless transfer is one of the important indicators of microgrids system.This paper firstly introduces the seamless transfer of master slave control and peer control about microgrids,and it detailed analysis the seamless transfer in microgrids' hierarchical control based on virtual synchronous generator.Finally,this paper designs the simulation model of inverter based on virtual synchronous generator,it includes single inverter of modified virtual synchronous generator,inverter paralleling system and seamless transfer.The simulation results verified the feasibility and effectiveness of the proposed control strategy.