Study On Bidirectional DC/DC Converter Of Photovoltaic System With Energy Storage

With the serious energy and environmental problems, renewable energy sources accept more attention, especially solar energy. Solar energy has obvious advantage in many sources. But in large-capacity photovoltaic power plants, solar impact on the grid by the Environment al Impact more and more obvious. This paper focuses on photovoltaic grid power problem of fast short-term fluctuations, adds bidirectional DC / DC converter to DC bus. The bi-directional DC / DC converter control strategies were studied.According to this feature of the inverter, this paper chooses to connec t the storage system to the bus, and use battery with power control strategy to suppressed the PV output power fluctuations. In this paper, through ana lysis and comparison of various non-isolated bidirectional DC/DC converter characteristics. In order to increase the power density, reducing the inductor size and reduce the loss, the two-phase interleaved topology structure is used. Complementary conduction of the upper and lower tubes of each bridge arm, the inductor current in discontinuous state, so not only can impro ve the sampling precision, but also can achieve soft switching.This thesis set up a small signal model in Buck mode and Boost mode and PI controller is designed. using power control strategy. The entire system is designed to operate in two modes; if grid PV grid power is required, the system can work in the upper command mode, but in this way the battery capacity is large and high cost, so the design of another modes, namely a low-pass filter mode, the system is equivalent to a filter capable of photovolta ic power output of the filter. Finally, the simulation analysis shows that both methods can be reduced the fluctuation of output power, improve power quality.A Matlab/Simulink simulation model of photovoltaic grid connected system with energy storage is built, and the parameters such as inductance, filter capacitance and so on are calculated. A 10 k W experimental platform is built and the sampling, drive, control IGBT overcurrent and by wave current limiting protection circuit and other hardware control cir cuit are designed, and the software of the main program process and software design process are introduced. by using DSP2812 control of battery charging and discharging, The experimental results can enough proved the correctness of the control strategy.