Research On Single - Phase Photovoltaic Grid - Connected Power Generation System Based On Z - Source Inverter

Modern industrial development requires huge amounts of clean and renewable power, the development of new sources of energy is becoming increasingly important, at present, more and more countries have begun to pay attention to the development of solar energy, as a result of solar energy’s large reserves and high safety factor. Photovoltaic grid-connected power generation technology has made great progress, but there has been some problems to be urgently solved, photovoltaic grid-connected power generation of low efficiency, high harmonic content, poor waveform quality and islanding effect have seriously restricted the application of photovoltaic power generation. To solve these problems mentioned above, this paper dealt with grid-connected photovoltaic system. The main contents of this paper are Z-source inverter and its grid-connected control method, photovoltaic maximum power point tracking, islanding detection technology.Some researches on topology and theoretical limitations of traditional inverter were done in this paper, on this basis, introduced the Z-source inverter topology, operating principle, commutation process and modulation method.Simulation studied output characteristics of photovoltaic cells, then several deficiencies of common MPPT control methods were summarized, on this basis, proposed a MPPT method based on fuzzy control, simulation verification was carried out on Matlab/Simulink platform, the simulation showed this method is better than P&O MPPT method.Studied grid-connected photovoltaic system based on Z-source inverter, and a meticulous research on double closed loop control was done, then the island phenomenon of PV grid-connected system was expounded, the basic principle of anti-islanding and commonly anti-islanding detection methods were combed, then an introduction was made to the principle of active frequency drift(AFD) method with positive feedback, this paper built a system modeling and made simulations for the proposed two types of strategies by using Matlab/Simulink, the results showed the correctness of methods.A device of Z-source PV grid-connected inverter was built, by using Renesas MCU HD64F2166VTE33V, the hardware parts of system such as drive circuit, sampling circuit, SPWM signal circuit were designed, and software system was studied, the experiment results verify the correctness and feasibility of Z-source PV grid-connected inverter.