Research On Control Strategy Of Grid-connected PV System With Reactive Power Compensation

With the increase of the energy consume, worsening of ecological environment and the improvement of the human environmental protection consciousness, people pay more and more attention to the development of renewable resources. As one of the important methods of photovoltaic applications, grid-connected PV system is a main development trend of renewable resource application in the future.This paper focuses on undispatchable grid-connected PV system.The topology, operating principles and the control strategy of grid-connected PV system are analyzed and studied in detail. On this basis, the paper has done a lot of experiments. The main contents are as follows:1. The principles and characteristics of different main circuit topologies of gird-connected PV systems are analyzed. And the model and vector relation of grid-connected inverter are built.2. To keep the frequency synchronous to the grid, a PLL (Phase Locked Loop) is necessary. The principle of PLL is studied in this paper, and a software PLL is designed based on practical system.3. Based on the theory of the instantaneous reactive power, the dq transformation is used to separate the inverter currents into the active currents and reactive currents. And in the future, PV grid-connected systems could be one of the most important means for improving the power factor of the main grid. This paper designed the control strategy of three-phase grid-connected PV system with reactive power compensation using the theory of the instantaneous reactive power. The voltage of DC link is analyzed from the point of view of energy, and a new control method is provided.4. The corresponding simulation model is set up using the simulation tool of MATLAB software, and related simulations are done. The results show that the control strategy is effective and available.5. The control program is developed based on the DSP (TMS320LF2407A) microchip. The experiments are done. The results coincide with the simulation, which testifies the effectiveness and availability of the control strategy.