The Reserch On 2000w Single Phase Photovoltaic Grid-conneceted Inverter

With the development of the world economy and the gradual depletion of the non-renewable energy resources such as coal,oil and natural gas,solar energy as the green renewable energy has become a popular alternative to support the growing energy demand towards the thermal power generation.Solar Power generation consists mainly of independent power generation and grid-connected power generation,among which photovoltaic grid-connected power generation is the predominant PV power generation method in the field.Among these techniques,control algorithms and islanding detection technology work as the core of grid-connected power generation technology.This article elaborates the research on control algorithms and islanding detection technology,and the primary work and achievements are as follows:1.Discussed the present situation of photovoltaic power generation technology,to determine six power transistors control logic by analyzing the full-bridge inverter circuit H6 four operating modes,and introduce a low-pass LC filter design methods,and by theoretical computing the reasonableness of the fi lter capacitance and inductance values is verified.2.Based on second-order generalized integrator of digital phase-locked loop technology to ensure single-phase grid-connected inverter output current and grid voltage same frequency and phase.Simulation analysis of the digital phase-locked loop technology to quickly lock the mains phase,and the prototype for the actual tests to prove the feasibility of this approach.3.Combined transfer function of a H6 full-bridge inverter circuit,we create a system under quasi-resonant controller proportion of open-loop transfer function,the use of the open-loop transfer function Bode diagram of the control parameters tuning method uses bilinear discrete digital control.Finally,we realize the prototype testing and grid-connected inverter incorporate in power network.4.The use of virtual capacitance method solves the non isolated grid connected inverter DC injection problems;in the simulation prove the effectiveness of suppressing DC injection method.Also analyzed the mechanism of islanding effect,with digital phase locked loop technology in this system,put forward the islanding detection method is an improved active frequency disturbance,the method can successfully detect islanding and shut off the inverter in MATLAB simulation.This thesis will quasi proportional resonant inverter algorithm application and voltage feedforward combined in a prototype of the TMS320F28035 as the control chip,the successful implementation of grid connected 2000W rated power,and the distortion coefficient control within 4%,the total harmonic.