Design And Research Of High Power Three-Phase Photovoltaic Grid-connected Inverter

With the rapid growth of the global industry and economy,the global demand for energy has increased.Traditionally,fossils have been converted into electrical energy.However,due to the non-renewable nature of fossil raw materials,energy has gradually become a hindrance with economic growth.The problem of sustainable development in the world,so in recent years,countries are developing renewable energy supply models.Among them,solar power generation has gradually become the key development direction of renewable energy due to its characteristics of cleanness,high efficiency and safety.Photovoltaic grid-connected inverter is the key equipment for energy conversion and grid connection in solar power generation system.Its performance and reliability determine the investment return period of the entire photovoltaic power station.Firstly,it introduces the background of the project and the research status of various key technologies of photovoltaic grid-connected inverter.Then,in-depth study of the phase-locked loop of three-phase voltage is carried out.The parameter design method based on the bandwidth of the phase-locked loop is deduced.The performance of the phase-locked loop in the case of grid fault is analyzed and discussed.The positive and negative sequence separation method of sinusoidal amplitude integrator focuses on the digital implementation of sinusoidal amplitude integrator,and its theory is verified by simulation.Combined with the protection needs,this paper adopts the grid-connected control method based on the inverter side current and capacitor voltage feedforward,and analyzes the current closed-loop parameter design method and the effectiveness of the capacitor voltage feedforward active damping control.At the same time,the given-feedback is proposed.The current-weighted decoupling control method is verified by simulation and experiment.Then,with the goal of developing a 500 kW high-power three-phase photovoltaic grid-connected inverter,according to the market demand and relevant industry standards,the development parameters of the products were determined,and the design of the power main circuit of the high-power inverter was designed and studied.Finally,according to the relevant standards of the industry,a complete laboratory system test platform was built,including a high-power grid simulator and a high-power photovoltaic array simulator.On the platform,the prototypes of the developed engineering prototypes were tested and finally passed.Industry CQC type test,certification and State Grid's low voltage ride through test certification.