Research On The Grid-connected Photovoltaic Power Generation System With Energy Storage Module

As the global energy situation is not optimistic at present, the development of new renewable energy and the transformation of energy structure has become the trend of The Times. The solar energy resource, one kind of widely distributed, clean and infinite energy, has become an important object of study. In the modern industry, electric energy is the most direct use of energy. And using solar energy in electricity generation as an important supplement for power grid is a research hotspot. Because of external environment and load, the electricity generated by solar energy is not steady, and grid-connection is an adverse effect for the grid. Considering the problem, how to use solar energy to generate steady electricity efficiently and feed the grid without adverse effect is the key research direction at present.Designed one kind of energy storage device that can supply power continually. The energy storage device includes charge and discharge control system and storage cells. Considering the technology of storage cells is mature. This article researched charge and discharge control method. Charge is controlled by three stages, and discharge is controlled by voltage. Designed double closed loop strategy consisted of voltage outer loop and current inner loop. This kind of control strategy is able to prolong the life of storage cells. The output power of photovoltaic cells array is changed under different environments or loads. In these situations, there is one and only one maximum power point. In order to let photovoltaic cells array work in the maximum power point in real time efficiently, designed a new conductance increment control algorithm that is started by constant voltage and tracked by variable step. By this way, the photovoltaic cells array just cost0.05s to achieve steady status, and the fluctuation of power is very slightly. Designed three-phase grid-connection inverter, which can supply redundant electricity energy to power grid. By this strategy, waste is avoided, and cost is saved. When the electricity generated by photovoltaic cells array cannot undertake the load, grid will supplement energy to the system. The inverter was designed to be one kind of voltage and current double closed loop control system based on space vector. In this way, DC bus voltage can be stabilized and unity power factor output does not have harmful effect on power grid.As the system have seven different working statutes in different load and its environment, designed switching control strategy of working statutes, adjusting working model of photovoltaic cells, storage system and inverter. Finally, on the basis of principle analysis and design of control strategy, set up the overall system model and analyzed each kind of working mode of the system by Simulink software.1he result of simulation proved the working statutes of the system’s models.