The Development Of The Inverter In A Small Scale Off-grid Photovoltaic Power System

With the rapid development of the society and economy, the huge demand for energy ofthe human have increased rapidly, researching and developing the new energy sources havebecome the consensus of the countries in the world. Solar energy is of one of the new energieswhich have the largest the value of promotion. Among the solar energy, the small scaleoff-grid photovoltaic power generation system is an important form of utilization of solarenergy because it’s low cost, easy to install and the system control technologies are relativelymature, it has been widely used around the world. The core technologies of the the small scaleoff-grid photovoltaic power generation system include high-efficiency photovoltaic celltechnology and system control with inverter technology. Therefore, this article has made astudy on the inverter of the small off-grid photovoltaic power generation system, designed asimple, easy to control and cost-effective off-grid inverter.. In order to achieve the target ofthe dynamic performance and steady-state performance, this article will use the deviceTMS320LF2407A DSP to control, use the control algorithm of the combination of PI controland repetitive control, to make the hardware and software design of the off-grid inverter, inorder to effectively inhibit the interference brought by the non-linear loads and the dead timeeffect.Details are as follows:1. Analyze the structure and working principle in the small scale off-grid photovoltaicpower generation system, and focus on control technology and commonly used controlstrategies of the inverter in a small scale off-grid photovoltaic power generation system.2. On the basis of comparation and analysis of a variety of structural topologies, thisarticle has made the single-phase full-bridge topology as the main circuit topology, and madethe bipolar SPWM modulation, then established and analyzed the mathematical models of theSPWM inverter and output LC filter.3. Make deep research and analysis on the structure and principles of the two controlalgorithms respectively, compare the advantages and disadvantages through theoreticalanalysis and Simulink simulations. Simulation studies have verified the superiority of PI+repeat complex control algorithm compared to the PI control or the repetitive control.4. Finally, on the basis of the above theoretical analysis and simulation studies, design ahardware and software system prototype of the inverter in the1kW small scale off-gridphotovoltaic power generation system. Through simulation analysis and prototypeexperiments, the distortion of the output voltage waveform based on PI+repeat composite control in the small scale off-grid photovoltaic power generation system is very small and canquickly and accurately follow the reference voltage waveform, fully meet the requirements ofthe inverter.This research has laid a good foundation for the development and industrialization of theinverter device in the small scale off-grid photovoltaic power generation system.This paper is supported by the Guangdong Science and Technology Program(2007B010400080/2010A010200004), the Produce-Study-Research Combination Project ofGuangdong Province and Ministry of Education (2009B090300424), and Guangdong-HongKong Technology Cooperation Funding Scheme (TCFS) of2010(20100107-3).