Research And Design On BMPV Grid-connected Inverter Of Photovoltaic Generation System

In countries around the world race to develop green renewable energy, solar energy has been unanimously favored by virtue of their unique advantages. In the various applications of solar energy, photovoltaic applications concerned a lot. Continue to lower prices of PV modules and photovoltaic technology, solar PV systems will gradually from the current supplementary energy transition to alternative energy. Grid-connected systems will become the mainstream of photovoltaic power generation system. The construction and power generation system (BMPV) is an important one in grid market in the future. Household type of small-capacity (5.5KWp) BMPV grid system made a detailed study and design in this paper.Conducted a systematic study of the solar PV modules in the grid system, analyzed the non-a linear output of PV modules of the output voltage, current, power curve with their temperatures and light intensity in different combinations, established of the new photovoltaic model more in line with the actual situation. Photovoltaic models are generated in different block when the effect of the hot plate, and proposed appropriate solutions.Studied several control strategies of Maximum Power Point Tracking (MPPT) of photovoltaic inverter system. According to the power of observation disturbance loss is big etc, this paper puts forward a new method that is improved adaptive optimal gradient method which can achieve fast and accurate power tracking. The method of variable step size link after equivalent treatment is more suitable for engineering practice. A MPPT simulation model established in Matlab/Simulink. The simulation waveform results of new method further is verified better then the incremental conductance method control strategy.Researched and designed the main circuit of the inverter system, used non-isolated inverter full-bridge inverter topology and determined the unipolar SPWM modulation. Analyzed and studied the DC bus capacitor parameters and the filter of AC, designed a LCL-type AC filter with damping and analyzed its amplitude frequency and phase frequency characteristics.Systematic studied the control strategy of the inverter system, using the PI control of the instantaneous current control strategy, while the introduction of the DC bus voltage control of the outer voltage PI control. Modeled and designed the PI parameters of the voltage and current closed-loop. In order to eliminate the impact of the grid voltage to grid current, introduced of the grid voltage feed-forward control strategy.Built a Matlab/Simulink of simulation model, studied and test the simulation of the entire grid system, then analyzed the output curve of simulation, Verified the correctness and accuracy of the every aspect of this model and research methods.