Research For Photovoltaic Generation Inverter Control System

With the rapid development of our society, the demands for energy are growing bigger and bigger. This makes people continue to think of new ways to develop and utilize energy. Photovoltaic power generation draws more and more attention from various countries around world and the researches of photovoltaic inverter system has become a relatively hot topic. This article is mainly about the study of the photovoltaic inverter control system. A Design of the photovoltaic power generation inverter control system has been built with the three-phase four-leg inverter topology, the DSP, FPGA coordinated controller. System’s performance indicators meet the practical needs through the experimental verification of this inverter system prototype.In this paper, regarding the phase control strategy as the core control theory, the single-phase SPWM control system has been designed. On the basis of three-phase four-leg inverter decoupling control, a polycyclic control system of the voltage and phase has been constructed with the phase control. Through modeling and system simulation, we proved the feasibility of the system.In the first part of this paper, considering the three-phase unbalanced and nonlinear load, basing on the analysis of the original topology of three-phase inverters, the main circuit using three-phase four-leg inverter topology has been built. We choose IGBT as the power switching. Meanwhile, in order to meet the inverter system’s Industrial frequency sinusoidal output, this article has also designed power filter, and determined the system parameters of the circuit.In the middle part, this paper presents the control system of the inverter. To make the data sampling, control algorithms and drive signal generated simultaneously, the system uses the DSP and FPGA as a central control unit. DSP is responsible for the data acquisition, and also responsible for the control of algorithm; FPGA generats the drive signals and completes the commands and the parameters transmission. The central control unit DSP and FPGA hardware circuits the minimum system has been built and through software the control algorithms and function has been fullfilled.Then we designed the communication management system for the inverter system. In the communications management system, PLC is used as the core. It responsible for receiving the control commands and parameters which send from the touch screen. And then sends it to the central control unit to complete instructions action and set parameters. At the same time PLC will also sent the data and status to the touch screen for display, which collected by the central control unit. The connection between PLC and the control unit is mainly through the communication between PLC and FPGA to achieve. In this paper, based on the Modbus communication protocol, we defined a format of sending and receiving data, which is suitable for the system. Then through the design of the procedure, it achieved the communication of the system.At last, a photovoltaic inverter control system experiment platform has been designed and built. Through the simulation test environment of debugging, the collected data and waveforms during experimental debugging process, the experimental results show that, the indicators of the system achieved the desired goals.