The Research On Unified Control Of Grid-Connected PV System And Reactive Power Compensation In Microgrid

With the development of grid-connected PV system, more and more Photovoltaic Power Generation hook up to the grid, it bring many negative influence to the power grid. On the foundation of research on the Microgrid, the paper mainly conduct a study on grid-connected PV system, the mathematical and Engineering Model is analyzed thoroughly so that we can analysis the character of solar PV cell and get the discipline that illumination intensity and environmental factor impact on its output power. on the basis of summarizing existing Maximum Power Point Tracking method, it make improvement to the Perturbation and Observation Method. An improved Maximum Power Point Tracking method with variable step for0.5times is proposed. The improved method remedy many defects of traditional method. Considering the main circuit of STATCOM and PV grid-connected inverter are consistent, the paper Points out that grid connection of PV system and reactive power compensation can be unified controlled so that it will solve the problems of reactive power in Microgrid.What’s more, it further analysis advantages and disadvantages of various PWM pulse control mode,and detailedly deduce the calculation formula of PWM pulse duty cycle of deadbeat control in three-phase PV system. Combined with the real-time detection method for reactive power current in three-phase power system based on the instantaneous power theory, it deduced the referential current alculation formula under various conditions in PV grid-connected system and a lot of simulation test was conducted to verify its exactness.Finally, it design the control system based on the TMS320F2182DSP chip,power circuit, signal acquisition and regulation circuit of DC and AC side, phase lock circuit, the protection circuit of PWM pulse Based on CPLD and the optical fiber transmission circuit of PWM pulse signal o of the PV grid-connected system.