| Photovoltaic power generation is susceptible to the influence of external environmental parameters,and has problems such as unstable output and large fluctuation.The introduction of energy storage technology can realize energy shifting,reduce power fluctuation range and smooth power output.Therefore,it is of great significance to study the energy storage system.Among them,the energy storage converter as the key to connecting various energy storage units,is particularly important for its research.In this thesis,the energy storage converter is regarded as a new two-phase interleaved parallel bidirectional DC-DC converter.The four switching tubes are controlled to work alternately to make them work in different subsystems.The switching tubes are also strongly nonlinear devices.The traditional PID algorithm is simple in structure and easy to implement,but it cannot be controlled precisely.Aiming at this system,a new double closed-loop fuzzy PID control method is proposed The main work is as follows:(1)The output characteristics and working principle of the photovoltaic cell are analyzed,and the hill climbing method is adopted as the control method of the maximum power point tracking.And the simulation model is established to analyze its adaptability to changes in temperature and light intensity.(2)The structure of the photovoltaic energy storage system and the characteristics of common batteries are introduced.Finally,lead-acid battery is chosen as energy storage battery and the control strategy of charging and discharging phase separation is determined.(3)The topological structure and working principle of the single-phase bi-directional DC-DC converter are analyzed in detail,the model of energy storage system based on single-phase bi-directional converter is established,and the voltage and current double closed-loop fuzzy PID control is carried out,it is verified that the control method can stably realize the two-way flow of energy.(4)In view of the shortcomings of single-phase converter,a new two-phase converter topology is proposed,and the working principle is analyzed,the main circuit parameters are designed.Based on the traditional PID control algorithm,the artificial intelligence PID algorithm is introduced.Three artificial intelligence PID algorithms are established to simulate the block,which are single neuron PID,BP neural network PID,fuzzy PID.And applied to photovoltaic energy storage system.The experimental results show that compared with the other three control methods,the battery energy storage system based on fuzzy PID control has good stability,fast system response,and small output ripple. |
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