Research On MPPT Algorithm For Two Stage Photovoltaic Inverter

With the increasing demand for energy and the increasingly serious problem of carbon emissions, the photovoltaic power generation as a renewable energy technology gets more and more attentions. As the maximum power point tracking(MPPT) which is one of the key technologies of photovoltaic system can improve the efficiency of the photovoltaic system, it has very high research value. Based on this, the MPPT technology of the two stage photovoltaic inverter is researched in the thesis:Firstly, by comparing some common solar cell models, the photovoltaic array simulation model is established by using the five parameters model. And the output of 3kW photovoltaic array under any conditions is obtained. On this basis, by using the local linearization of the obtained PV model, the small signal model of the two-stage photovoltaic DC-DC system is obtained. Then, according to the obtained small signal model, the compensation network which can improve the system stability is designed. Through the comparative analysis of disturbance observation method and incremental conductance method, the incremental conductance method is chosen to improve from constant voltage start,variable step size and the reduction of misjudgement. The improved incremental conductance method can effectively reduce the influence of the variation of the light intensity on the performance of the algorithm. Lastly, based on the further analysis of the multi-peak output characteristic curve, the improved conductance increment method is used in global search, which can solve the problem that the improved conductance increment method would restricted into a local peak power point when the light intensity is complex and the PV array output curve showed multi-peaks. Finally, the system model which is built on Matlab simulate the above theoretical analysis and algorithms. The simulation results certify the availability of the thesis.