Research On Output Impedance Of Droop Control Inverter Based On Sensitivity Analysis

With a large number of distributed generation connected to microgrid,droop control strategy has been widely used.The effective control of output power by droop control inverter is closely related to the output impedance characteristics of inverter,and the power control effect not only affects the normal operation of electrical equipment and the power quality of power users,but even endangers the safe and stable operation of microgrid.Therefore,it is of great significance to study the output impedance of droop control inverter for the stable and safe operation of microgrid.In this paper,by designing the output impedance parameters of the inverter,the output impedance of the inverter is reshaped to solve the problem of reasonable power distribution among distributed power sources in microgrid.The establishment of droop control inverter output impedance model is the basis of studying inverter output impedance.By analyzing the mathematical model of inverter,this paper designs the voltage-current double-loop control,deduces the inverter output impedance transfer function,establishes the droop control inverter output impedance model,and determines the influencing factors of inverter output impedance by analyzing the inverter output impedance model.In order to solve the problem that the influence of the interaction between parameters on the output impedance of droop control inverter is unclear in the design of output impedance parameters,this paper uses Sobol"s global sensitivity analysis method to analyze the sensitivity of output impedance parameters of droop control inverter.Through the analysis and evaluation of parameter sensitivity,the influence of each parameter of droop control inverter output impedance and the interaction between parameters on inverter output impedance is made clear.To solve the problem that the design method of output impedance parameters of droop control inverter is unclear,this paper proposes a design method of output impedance parameters of inverter based on impedance electrical characteristics.The method is based on the conclusion of sensitivity analysis of output impedance parameters of droop control inverter,establishes the relationship between inverter output impedance parameters according to the electrical characteristics of droop control inverter output impedance,and explores the design method of inverter output parameters.By shaping the output impedance of droop control inverter,the influence of line impedance on inverter output power is overcome,and the power distribution accuracy among distributed power sources in microgrid is improved.The simulation model of isolated island microgrid is built,and the output of inverter is analyzed under different line impedance characteristics,so as to verify the effect of the design method of droop control inverter output impedance parameters on the modeling of inverter output impedance.The simulation results show that the problem of low distribution accuracy among distributed generators in low-voltage microgrid is solved by reshaping the output impedance of inverter.