Research Of Control Strategy Of Grid Connected Inverters In Low Voltage Micro-grid

With the emergence of the new power network structure of micro grid,the grid connected control has become a hot research topic at present.In this paper,the control strategy of the grid connected inverter in low voltage micro-grid is analyzed and studied.The control strategy of single phase inverter based on user side micro grid is proposed.The main objective of this strategy is to reduce the harmonic frequency of the output voltage of the single phase inverter system in the micro grid which is close to the user side.First of all,this paper analyzes the operation principle of the grid connected inverter.At the same time,the parameters of the filter in the grid connected inverter system are designed.Comparing the different topologies of grid connected inverter,the mathematical model of the inverter in low voltage micro-grid is established.According to the basic operation principle and parameter design of the low voltage grid connected inverter.The main circuit of grid connected inverter is presented in this paper.Grid connected inverter main circuit using two stage energy conversion structure.The front stage uses a boost topology,and the later stage uses a single phase inverter topology,Output filter using LC filter.Secondly,based on the main circuit of grid connected inverter,the control strategy of grid connected inverter is proposed.The changes of network topology in two different states of grid connected and isolated island are summarized.The control strategy of several traditional classical inverter control strategy and the control strategy of modern advanced control theory are introduced.The PID control strategy of grid connected inverter,the robust control strategy and the sliding mode variable structure control strategy of the grid connected inverter are analyzed.the practical application of inverter technology in solar power generation system is realized,To realize the control strategy of grid connected inverter.Again,the control based on the user side of the micro grid inverter is designed.Aiming at the nonlinear load condition,the PID controller is used to control the single phase inverter in the user side,which can't achieve a good harmonic suppression effect.A double feedback control strategy is proposed to design the system controller.Control method combining robust control of voltage outer loop servo system and sliding mode control of current inner loop.Finally,Simulation of the control strategy system based on the user side micro grid single phase inverter is carried out through MATLAB/Simulink.The simulation results show that the nonlinear load,this method can effectively suppress harmonic frequency,it is able to track the reference voltage.