| This thesis proposed the use of hydrogen storage technology to solve the problem of large-scale wind and photovoltaic abandonment as well as the problem of grid-connected power generation of Wind-Photovoltaic-HESS(Hydrogen Energy Storage System)-BESS(Battery Energy Storage System)microgrid system.Taking the Wind-Photovoltaic-HESS-BESS micro-grid as research objesct,wind power generation,photovoltaic array,alkaline electrolyzer,high pressure hydrogen storage tank and ideal compressor,PEMFC(proton exchange membrane fuel cell)and auxiliary lithium storage unit working principles and operating characteristic curves are analyzed,and the mathematical models of corresponding modules are established respectively.The part of HESS is based on electrolyzer and fuel cell as the core,including U-I characteristic model,efficiency model,hydrogen production model,ideal compressor pump model,etc.By analyzing the steady-state and dynamic operation characteristics of HESS,and adding the consideration of separate hydrogen sales and temperature change,the integrated dynamic model of HESS is established and verified in the simulation software.Based on the proposed model,in order to ensure the safe and stable operation of the microgrid system in grid-connected condition,an improved PQ control strategy is proposed to improve the grid-connected stability of the system for the wind-photovoltaic-HESS-BESS microgrid and stable grid-connected and smooth hydrogen production.The charging/discharging control of HESS and BESS,error regulation control of voltage phase and amplitude,and pre-synchronization control ensure that the inverter enters the grid-connected operation smoothly,thus reducing voltage and current shocks at the grid-connected common connection point and improving system safety and reliability.The HESS can produce hydrogen in the operating area,for example,in the range of 63～299NL/min adjustable for 100 k W hydrogen production.For the fuel cell power stack,the power generation capacity is adjustable within 10～100k W.The effectiveness and feasibility of the proposed control strategy are verified by building a simulation model of the wind-photovoltaic-HESS-BESS microgrid in Matlab/Simulink platform.In order to realize the optimal scheduling of the integrated wind-photovoltaic-HESS-BESS microgrid system with real-time tracking of the day-ahead power generation plan of the grid,and considering the peak-valley price tariff rules,combined with the spatial and temporal displacement characteristics of the energy storage system,the microgrid system produces hydrogen and hydrogen fuel cell power generation with the highest economic efficiency.In this thesis,on the basis of the proposed mathematical model of each subsystem of HESS,the mathematical equations of day-ahead and intra-day rolling optimal dispatch are derived and analyzed.Taking the highest overall economic return of the system as the objective function,considering the power balance,storage system state of charge(SOC)and other index constraints,setting the weight coefficients of two types of energy storage systems in the system with the principle of priority power output of the HESS,and using the improved particle swarm optimization algorithm to iteratively optimize the system objective function to obtain the system day-ahead optimal scheduling curve.Then the intra-day real-time rolling optimization is carried out by MPC with a rolling period of 15 min and the tracking day-ahead scheduling curve and the economic efficiency optimum as the dual objective function to achieve the economic efficiency optimum intra-day accurate scheduling.Finally,the proposed optimal scheduling method is simulated and verified in MATLAB by setting the actual wind-photovoltaic-HESS-BESS-load and other parameters. |
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