Design Of Microgrid Grid-connected Inverter System

In recent years,with the rapid development of industry and the increasing demand for electricity,the drawbacks of traditional power system such as energy crisis,environmental pollution and other issues have become increasingly prominent,therefore,the microgrid will become the future trend of development.Microgrid is set a variety of distributed energy,promote the new network structure of centralized and decentralized coordination,flexible position,energy saving and environmental protection,variety structure,plug and play,improve the stability and security of power system.Photovoltaic power generation has become one of the most promising sources because of its flexibility,cleanliness and universality.Solar energy is inexhaustible,green environmental protection,sustainable development to energy,is the world recognized the most ideal alternative new energy source,therefore,it is very important to research the technology of grid connected photovoltaic power generation based on.In this paper,the design of grid connected photovoltaic inverter system is studied.The paper first analyzes the grid inverter system's overall structure,the selection of inverter and the selection of control mode.The analysis of the output characteristics of photovoltaic array and MPPT control strategy,and set up the MATLAB simulation model was verified.Secondly,in the parallel double closed-loop control strategy and based on the theory of voltage SVPWM modulation technology of on the voltage outer loop and current the inner loop and phase-locked loop design.Through the analysis of several traditional islanding detection methods,this paper proposes a method for islanding detection based on wavelet analysis,and the detection method of high efficiency and high precision and can overcome the blind spot detection and harmonic pollution problem is verified by simulation.Finally,the hardware and software of the grid connected inverter system are designed,including the hardware design of the boost inverter circuit,the drive sampling circuit,the control circuit and the auxiliary circuit,and the software realization of each part of the control algorithm in DSP.According to the theoretical analysis of building MATLAB simulation model to verify the feasibility of the design,according to the hardware and software design,build the experimental platform,the experimental waveforms are given.The experimental results show that this design is good to complete and comply with the State of the grid connected requirements.