Control Strategy Of Inverter Based On Voltage Source Output

In order to make better use of distributed power,make the distributed power access to the grid in the form of micro-grid,it can give full play to the advantages of distributed power generation.When the grid is running normally,the microgrid system can be connected to the grid,and the grid system can still supply the load when the grid fails.It can greatly enhance the safety of the power system and the reliability of the power supply.When the microgrid is in the island mode,at least one distributed power supply with a voltage source output characteristic is required to provide voltage and frequency support for the microgrid.In this paper,the inverter control system based on the output of the voltage source is designed in the two-phase synchronous coordinate system and the two-phase stationary coordinate system,and the equivalent output impedance of the inverter is analyzed and compared in different coordinate systems.In order to increase the reliability and security of the microgrid system in the island mode,on the basis of combined virtual inductor technology,the droop control is performed on the inverter based on the voltage source output,to achieve multiple inverters without communication signal line running in parallel.Simulation and experimental results show that the designed parallel system has good control performance.The implementation of grid-droop control of the inverter based on the output of the voltage source can realize the seamless switching of the grid mode and the island mode.In the case of grid connection,the inverter generally adopts constant power control mode.Based on the analysis of the shortcomings of the traditional droop control strategy,an improved grid-connected droop control strategy was proposed,which suppress the influence of grid frequency fluctuation on the output power of the inverter by increasing the angular frequency feedforward of the grid,achieve reactive power without static tracking and suppression of grid voltage amplitude fluctuations on the reactive power of the impact by adding the integral controller.Simulation and experiment verify the effectiveness of the proposed improved grid-connected droop control strategy.