Photovoltaic And Energy Storage Generation Control Strategy Research Based On Hybrid Energy Storage

With the progress of the society and development of economy, human face more and more resources shortage and environmental pollution problems. Photovoltaic power generation is an important way to solve energy crisis and environmental crisis. However, the randomness, volatility and intermittent of photovoltaic power bring a serious threat to the safe and stable operation of power grid. Combined with battery and super capacitor, hybrid energy storage can stabilize photovoltaic power fluctuation. Besides, it can overcome the short life and poor efficiency drawbacks of battery as well as the low energy storage ability drawback of super capacitor. It helps to stabilize photovoltaic power and has a great significance in interconnection and operation of photovoltaic system. This paper adopts hybrid energy which combines battery and super capacitor to stabilize photovoltaic power and puts forward an energy control method.For the study of control strategy of hybrid energy storage, use three-stage charging method to research the battery charging characteristics. Experimental results show that effected by polarization, battery can be charged maximum to 60.97% in constant current charge stage. The super capacitor charge and discharge characteristics are researched by MATLAB/simulink. Simulation results show that super capacitor doesn't exist polarization effect and its capacity almost can be fully utilized. The characteristics of battery, super capacitor and hybrid energy storage are studied and the hybrid energy storage has obvious advantages.To configure hybrid energy storage capacity rationally, according to long time photovoltaic power data, a battery and super capacitor capacity configuration method is put forward. Hybrid energy storage is connected to photovoltaic system in DC side. Based on low pass filter, a control strategy that low frequency photovoltaic power fluctuations are smoothed by battery and high frequency photovoltaic power fluctuations are smoothed by super capacitor is put forward. Considering the influence of polarization effect on the battery, the adjusting charge and discharge filter time parameter control strategy based on SOC feedback is proposed. With the strategy, battery increases charge power when SOC is low and decreases charge power when SOC is high. Battery can work in power controllable state more and its service life is extended.The experimental platform of photovoltaic system and hybrid energy storage are set up to verify the proposed control strategy. Experiment results show that in energy storage side, battery and super capacitor can smooth photovoltaic power fluctuations respectively in different control cycle. When battery SOC is too high, the battery filter time parameter is adjusted by SOC feedback, which can limit the battery output power and avoid excessive charge. In photovoltaic system side, when photovoltaic power increases or decreases abruptly, hybrid energy storage can compensate power vacancy, which plays a significant role in smoothing photovoltaic power fluctuations. The feasibility of the proposed control strategy in this paper is verified by experimental results.At last, the photovoltaic and storage generation system energy control method is proposed. In an isolated system which consists of photovoltaic power generation, battery, controllable load, daily load and emergency power supply diesel generator, according to photovoltaic power prediction data, the energy control method draw ups the generation plan and utilization plan of each component to ensure the stable and economic operation of system. The validity, feasibility and economy of the proposed energy control method are verified by examples.