The Research Of Low Power Photovoltaic Grid Connected Control System Based On DSP

As the energy shortage and environment deterioration, renewable energy become moreand more popular. Among them, with the advantages of rich in resources, friendly toenvironmental, and can be large-scale development, the solar energy become the focus allover the world. Photovoltaic power generation is one of the main ways. As the importantdevice of photovoltaic power generation systems, its topology structure and control algorithmof photovoltaic grid-connected inverter has becoming a hot spot in the photovoltaicapplications field.Based on the photovoltaic grid-connected inverter. This paper carry out the research fromthree aspects: the topology of the inverter, the maximum power point tracking, and the gridinverter control.500w DSP28335as main control chip have been designed for thephotovoltaic grid-connected inverter. The hardware part of the inverter is mainly consist ofthe sampling circuit, drive circuit, control circuit and power circuit. In view of the low outputof the single stage type power, the weak anti-interference, we have designed the isolatedinverter topology structure of two levels. Based on this, we puts forward the MPPT algorithmof variable step disturbance observation method, and has carried on the modeling andsimulate it by MATLAB. Constant with the pressure disturbance observation method,incremental conductance method, perturbation and observation method. Founding thatperturbation and observation method with changing perturbation step can adjusted the steplength according to the change of the power on real-time, and it can track the MPP pointsquickly, comparing with the traditional algorithm. It has overcome the weakness of MPP pointmisjudgment and oscillation. Improved the phenomenon of the influence of factors such astemperature, illumination by the traditional photovoltaic. At the same time, in view of thepoor quality of the grid power and the large losses of switching, Adopting the voltage currentdouble loop control algorithm based on the SPWM, making the grid-connection have thesame frequency and phase.Through the combination of hardware and software, made a500w photovoltaic grid-connected inverter. Built experimental platform based on the inverter, conduct MPPT andgrid-connection experiments by the shield method and double loop control, the experimentaldata validated the structure design and control strategy of inverter, and can run stably andreliably.