Research On Single-Phase Photovoltaic Grid-Connected Inverter Based On Virtual Space Vector

With the increasingly prominent energy and environmental issues,new energy power generation technology has received more and more attention,and solar power has occupied an important position in the field of clean energy applications.The photovoltaic power generation system is mainly composed of a solar battery,a boosting circuit,a grid-connected inverter,and a control circuit.The grid-connected inverter is the key equipment to realize the electric energy conversion.Therefore,it is of great significance to study how to improve the current output response characteristics of the photovoltaic grid-connected inverter and improve the photovoltaic grid-connected current quality.Firstly,this paper introduces the development situation of photovoltaic power generation and the research status at home and abroad from the perspective of energy.It briefly summarizes the key technologies of grid-connected photovoltaic power generation and explains the main work of the paper.According to the working principle,topology,modulation method,input mode and control strategy of single-phase photovoltaic grid-connected inverter,the system structure of the pre-Boost boost plus post-stage single-phase bridge inverter is designed and the corresponding mathematical model is established.The working principle is analyzed and the corresponding control model is established.Secondly,from the perspective of vector control of three-phase grid-connected inverter based on dq synchronous rotating coordinate system,the existing defects of single-phase grid-connected inverter vector control technology are analyzed,that is,there is only one single-phase grid-connected inverter.The grid voltage and grid-connected current cannot be directly transformed into coordinates.The method of directly obtaining the virtual physical quantity by delaying the actual physical quantity by a quarter of the grid period seriously deteriorates the dynamic response of the system and increases the complexity of the system,making the system slow or even causing oscillation.In this regard,this paper proposes a method of virtual orthogonal quantity construction based on indirect delay,which derives the virtual orthogonal quantity with a small delay physical quantity,and the introduced small delay is much less than 1/4 grid period.On the basis of solving the large delay problem,this method does not need to adopt complex algorithms,and is easier to promote in engineering.Finally,the simulation model of single-phase photovoltaic grid-connected power generation system based on indirect delay method is established by using MATLAB software.The indirect delay method proposed in this paper is used to construct the orthogonal virtual quantity to realize single-phase photovoltaic grid-connected inverter.The effectiveness and feasibility of vector control greatly improve the dynamic response performance of the system.