The Research Of The Inverter’s Auxiliary Control Function Which Based On The Droop Control

Voltage sag is one of the most serious problem in power quality problems local bus voltagewould be affected by the grid voltage sag when the microgrid is “grid-connected”.So the paperaccording to the problem of the micro grid would be affected by the grid voltage sag,it researcheson the dynamic voltage support by the grid-connected inverters control mainly includes thestrategy of the system, the principle of the dynamic voltage support, Simulations`analysis,and thestability analysis of the power system.Design considerations of the dynamic voltage support, The controller and circuit aredeveloped to realize the principle that a voltage drop on the inductor generates when the reactivepower flows through it. Once the voltage sag of utility grid occurs, an arbitrary reactive power isinjected into the grid by grid-connected inverters, which generates a voltage drop on thedecoupled inductor to compensate the grid voltage sag.In order to realized zero-error-control,this paper has modified the the traditional droopcontrol in the system to make the value of the reactive power which output by inverters moreaccurate.Used the PR controller in the voltage loop and current loop and analysis of theparameters.For the problem of the decoupling inductance`s value in the power system, This paperanalyzes inductance from it`s structure, craft, loss and so on. Finally we got the better value sizeof the inductance which suited for the reactive power compensation.This can maintain the localbus voltage of micro-grids. According to the magnitudes of voltage sags, several actions of thegrid-connected inverters are designed and implemented to generate reactive power and maintainlocal bus voltage, which ensures the normal operation of loads. Design considerations of thecontroller are discussed in detail. Simulations by using MATLAB/Simulink are conducted,demonstrate the feasibility and effectiveness of the proposed method.