| Photovoltaic power generation is one of the most widely used ways of utilizing solar energy. It has been becoming scholars’main research and development hot spot in recent years. Coordinate control strategy is the core technology to improve the system performance and energy efficiency and is also the core research question of photovoltaic energy storage system. This paper introduces the photovoltaic energy storage system based on the common dc bus as the research object. It makes in-depth research for the system’s energy management scheme and the different power converter control method. It has important theoretical and practical significance.In traditional system energy management plan, when the system’s environment is badly changing, it is extremely easy to cause the charge and discharge of battery and damage to the battery, also reduce the battery life, increase the system cost and even make the system stop working seriously. According to the above problems, this paper establishes a set of complete energy management solutions, including the division of system working mode, the boundary conditions, also putting forward the specific energy management solutions for each mode, smooth switching between different working mode. This scheme takes into consideration of power full and power shortage situation to protect the battery. It makes photovoltaic energy storage system have strong applicable scope and wide application range.The ever adopted control method of the power electronic converter in photovoltaic energy storage is the closed-loop control (PI controller). This control method has too many controller parameters to adjust and control structure is complex. In this paper, by using the model predictive control (MPC), MPPT control method and two kinds of storage battery charging and discharging control methods based on the model predictions are proposed. This method is mainly establishing predictive model of system target to predict all the possible values of the next moment, and also formulating the objective function to choose the switch state of the power electronic converter to be minimized. The model predictive control method has simple structure, flexible control and is not sensitive to adjusting parameters, also has good dynamic and static performance.This paper designs a set of storage battery charging and discharging experimental platform. The platform firstly realizes the double closed-loop control (PI controller) of stored energy converter. The experimental results show that the dc bus voltage is stable through the battery charging and discharging and also realize the constant current charging and discharging of the battery. At the same time, it realizes the constant current charging and discharging of the battery with model predictive control having a good dynamic performance. At last, the model predictive control method controls the stored energy converter to realize the stability of the dc bus voltage. Compared with the double closed-loop control, it has a speed of switching between charging and discharging modes. |
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