Research On Current Control Technology Of Single Phase Inverter For Grid Discharge

Discharge test is a necessary way to detect battery capacity,maintain battery health and extend battery life.And grid discharge is an important means to bring energy back to the power grid and create benefits for power plants and users.It is the inevitable choice to realize the basic national policy of "protecting the environment and saving resources",and is the trend of the future development.Grid connected inverter as the interface of grid discharge system and power grid,the state has a clear standard for grid connected system,power quality,safety and protection.It can be seen that the power quality of grid connected system is a very important point,and the design of control system is the decisive factor of power quality.This paper first makes mathematical modeling,basic principle analysis and filter parameters design for various topology of grid connected inverters,and briefly introduces three common control techniques,PI(Proportional Integral),PR(Proportion Resonant),repetitive control and improved control,and analyses the basic principles,advantages and disadvantages as well as the applicable situations of each control.Then,on the basis of the actual device,the controller parameters are designed for PI,PR,and repetitive control.Through simulation and experiment,these optimal control methods,that is,PI+ repetitive control,are selected.At the end of this paper,the validity of the frequency adaptive repetitive control is verified by simulation and experimental verification of the nk±m repetitive control by simulation and experiment for the existence of PI+ repetitive control,such as the weakening of the harmonic suppression effect and the excess of some subharmonic suppression.The effectiveness and feasibility of complex control;finally,in view of nk±m repetitive control when n takes some values,it will cause the harmonic suppression frequency deviation problem.Using the idea of frequency adaptive repetitive control,an accurate nk ±m repetition control is proposed,and the validity of the control is verified by simulation,and its validity is proved.