Research Of PV Grid-connection System Based On SOPC

Solar energy is the focus of future energy development, because of its clean, environment and inexhaustible. PV grid generation is the main modality of solar energy utilization. As the core of PV grid-connection system, the grid controller plays a vital role in improving system performance and the utilization rate of solar energy. Up to now, the most controllers of PV grid-connection system have been the serial controllers,which are of slow operation speed, low efficiency and poor dynamical characteristics. Therefore, it is of very important practical significance to develop based-parallelism PV grid-connection controllers and to investigate their control techniques for improving the overall performance of system and promoting the development of PV industry. A proposal of a parallel structure PV grid-connection system based on SOPC and investigation of its grid-connection control technique are made, with the emphasis on the grid control strategy and islanding detection method.The main research work is as follows:1. A proposal of a parallel structure PV grid-connection system architecture with islanding detection function based on SOPC technique is preformed. The main circuit and the direct grid current PI control strategy with the grid voltage feed-forward control are determined by analyzing and comparing several common inverters main circuits and grid control operation of.2. An improved AFD islanding detection method based on the direct current amplitude perturbation is proposed, and its detection principle is described in detail. The effectiveness of the method is qualitatively assessed, and the grid current THD is quantitatively calculated.3. The design of the hardware and software for the system is completed. In the part of hardware, the main circuit, detection circuit, driving circuit and based-FPGA ADPLL module, AD control storage module, improved AFD module, PWM peripheral module and so on are designed, and the overall IP hard core of PV grid-connection system is constructed based on SOPC. In the part of software, the Niosâ…¡main program and interruption subroutine of the system are programmed.In order to verify the correctness of the design, a simulation and practical test of the grid control strategy and the islanding detection method are made by constructing a1kW PV grid-connection experiment system. The results obtained show that the system can effectively improve the tracking accuracy of system and the quality of grid current, and fast detect islanding effect with little the non-detection zone.