Control Strategy Of Three Phase Grid-connected PV System Based On Full Feedforward Of Grid Voltage

Since the world energy crisis and environmental pollution, renewable energy has been widely attention, the solar energy for resource diversity, no noise, no pollution, safe, and reliable, has a wide application range. Photovoltaic (PV) grid power as a main form of solar energy utilization, it is to use solar panels convert light energy into electrical energy, for the use of the user. Grid inverter is the core of photovoltaic (PV) grid power generation system, its performance not only affects and decides the whole PV grid-connected power generation system will be stable, safe, reliable and efficient operation, but also affect the service life of the whole system.At first, this paper starting from the basic structure of the PV grid power generation system, this paper introduces the simulation model of photovoltaic cells, the inverter topology, analyzed the characteristics of the LCL filter, and calculated the LCL filter parameters, then under the condition of ideal power grid voltage, in ABC, alpha, beta and dq three coordinates is deduced based on LCL, the mathematical model of three-phase photovoltaic (PV) grid inverter, compare the three coordinates of the difference between the model and its control, decided to adopt dq coordinate system to control, on the basis of the traditional PI control to introduce power grid voltage feed-forward control strategy, so as to reduce the distortion of grid voltage and affect the quality of grid current, and the control strategy was deduced under the transfer function of the system, and analysis the dynamic performance and steady-state performance. Three-phase imbalance occurs, and then, in view of the power grid is deduced from the grid voltage feed-forward control strategy, and verify its effectiveness, and combining with double decoupling phase lock technique under synchronous rotating coordinate system, the grid inverter output current meet the national standards. Finally in the matlab/simulink simulation model is set up, full validation of grid voltage feed-forward control strategy can realize astatic grid, at the same time set the grid unbalance situation, comparing the traditional control method and the improved method proposed in this paper, the advantage of the improved control strategy is verified.Simulation results show that the design of all feed-forward control based on grid voltage of PV grid power generation system can output has steady and dynamic performance of grid current, and when the grid unbalanced fault occurs, grid inverter can be stable and safe operation, ensure the stability of the power system operation and improve the life of the system.