Research Of Hybrid Storage System Based On Photovoltaic Generation

Along with the social progress and economic development, the existing energy structure has been unable to meet human needs. Some new energy can relieve the energy crisis. Solar energy with its clean environmental protection, huge energy, etc, become the focus of the countries around the world are scrambling for research. However, single photovoltaic mode under the condition of the bad weather may not be able to meet the normal demand of user. At this point, to join the energy storage system can ensure the normal order of the energy output, no longer subject to the influence of the external environmental factors, such as sunlight intensity and length of time.This thesis first introduces the major components of photovoltaic system, respectively given basic principles and mathematical models of batteries and supercapacitor, then focus on analysis of photovoltaic cells P-U and I-U properties and each hybrid energy storage system(HESS) element charge and discharge characteristics simulation analysis. With battery-ultracapacitor based on photovoltaic power generation, making use of high power density ultra capacitor to absorb impact power, reducing the impact power influence on battery life and the same time reducing the battery capacity configuration in HESS.Secondly, building the HESS and according to the 10 kinds of basic working states and load demand, make the one-way DC/DC converter and bi-directional DC/DC converter easily switch among the different working conditions. According to different working modes of different converter, using different control methods. One-way DC/DC converter works in the maximum power point tracking(MPPT) mode and constant voltage mode respectively using the conductance increment method and PID compensation control method; Bi-directional DC/DC converter working in the Buck and the Boost mode by bidirectional voltage-current loop control strategy. Integrated photovoltaic cells, battery and ultra capacitor charging and discharging characteristics, given an energy control strategy of HESS to ensure the reasonable and effective flow of energy in the system.Finally, giving the converter parameter design are given, building system model in Matlab/simulink for the simulation analysis, verifying working condition and control strategy correctness. The result shows that switch among different working states and cooperation between hybrid energy storage components fully meets the requirements. In addition, contrasting the system to reply with the resistance load and resistance-inductance load, it proves the feasibility and necessity of the system.