| At present,the excessive use of fossil energy has become one of the main reasons for the frequent occurrence of natural disasters in China and around the world.In order to change the status quo,energy conservation,emission reduction,and the promotion of renewable energy development are important development directions for the future of energy.Cutting peaks,filling valleys,and full consumption are the key guarantees for the high-quality development of the renewable energy industry.Therefore,it is important to control the power generation of renewable energy.The optimized operation of the system has become a research focus.This paper takes the wind-solar hybrid hydrogen production system as the research object,analyzes the working principles of direct-drive wind turbines,photovoltaic arrays,alkaline electrolyzers,proton exchange membrane fuel cells and energy storage lithium-ion batteries,and establishes mathematical models.The control of the converter is described in detail.In the part of the electrolyzer and fuel cell,the steady-state and dynamic output characteristics are analyzed;in the part of the energy storage lithium-ion battery,the influence of temperature,discharge rate and other factors on the battery is studied,and it is verified on the experimental platform.The parameters in the model adopt the recursive least square method with forgetting factor for online parameter identification to improve the identification accuracy.On the basis of the built model,an adaptive extended Kalman particle filter algorithm is proposed for the system as a whole to perform two-stage optimization scheduling,and at the same time optimize the operating range of energy storage batteries.Among them,the electrolyzer and fuel cell of the system absorb long-term power fluctuations based on a control algorithm,aiming to maintain a constant power for a long time,improving the quality of hydrogen energy,reducing the temperature rise caused by fluctuations,and extending the service life of the equipment.Short-term power fluctuations are borne by the energy storage lithium battery.As an auxiliary energy storage device,the battery reduces the requirements for its capacity and reduces the probability of return.In addition,the algorithm improves the accuracy of battery state-of-charge estimation,and can avoid battery overcharge and over-discharge based on the feedback state of charge and voltage fluctuations.Since the capacity expansion of hydrogen storage is easier to achieve than that of energy storage batteries,the proposal of this control strategy further effectively improves the energy utilization rate.In addition,the time-delay characteristics of the output power of the electrolysis cell and the fuel cell are fully considered,and the energy storage battery compensates for the time-delay power while smoothing fluctuations.The simulation results show that the control strategy proposed in this paper maintains the stability of the output power of the electrolysis cell and the fuel cell for a period of time,reducing the requirement on the capacity of the energy storage battery,avoiding the overcharge and overdischarge of the battery,and increasing the bus voltage stability. |
