Droop Control Strategy For Microgrid Inverter Based On Virtual Impedance

The global energy problem and environmental pollution are getting worse,people have eyes on clean energy and many countries carry out distributed power generation research.In recent years,distributed power generation has developed rapidly,Especially photovoltaic power generation and wind power generation.In order to make more efficient use of distributed power generation and play the advantages of distributed power generation,microgrid technology has attracted people's attention.The microgrid inverter is a key component of the distributed power supply connected to the microgrid,optimization control of microgrid inverter plays an important role in microgrid.When the microgrid is in island mode,the micro-grid inverter is capable of providing voltage and frequency support for the microgrid,it can automatically adjust the power output according to the load fluctuation in the microgrid,to ensure that the micro-grid internal energy supply and demand balance.In the absence of a communication line,the droop control strategy without a communication line allows multiple microgrid inverters with voltage source output to run in parallel,it can enhance the security of microgrid system operation.The mathematical model of the LC filter circuit of the micro-network inverter have been analyzed and establishes a double-closed-loop control system of the micro-network inverter based on the quasi-resonant controller.The output power of the microgrid inverter using the traditional droop control strategy can be divided according to the rated capacity of each inverter,but the reactive power will be affected by the impedance of the line.Therefore,this paper analyzes the output power characteristics of microgrid inverter using traditional droop control strategy,and make improvements based on the traditional droop control strategy.The problem of power inequality of the microgrid inverter in the island mode is solved by improving the droop control strategy.In this paper,a microgrid simulation model is built in the Matlab/Simulink simulation system environment,the simulation results verify the theoretical analysis of this paper and the effectiveness of the improved drooping control strategy.