Research On Multi-stack Fuel Cell Consistency And Hybrid Power System Hierarchical Energy Management Method

As an environmentally friendly,efficient and safe power generation device,fuel cells can directly convert hydrogen energy into electrical energy.They have been used in actual projects such as locomotives,submarines,and trams.In order to solve the problem that a single fuel cell is difficult to support high-power applications,and the pure fuel cell power generation system has problems such as insufficient dynamic response,multiple fuel cells and energy storage batteries can be combined to form a multi-stack hybrid power system.Based on the above considerations,this paper mainly studies the structure of the PEMFC multi-reactor hybrid power system and its energy management strategy.Through the research on the structure of multi-stack fuel cells and hybrid power system topology at home and abroad,the characteristics of different topologies are compared and analyzed,and a multi-stack hybrid system composed of three sets of fuel cells and a set of energy storage cells in parallel is designed.Each power source is controlled by an independent DC/DC converter.According to the different characteristics of fuel cells and energy storage batteries,one-way and two-way DC/DC converters were designed respectively,and a physical test platform for a single-stack fuel cell hybrid power system was built to evaluate the actual input and output characteristics of the fuel cell power generation system.Test and analysis provide basis and measured data for the establishment of simulation model.Then,according to the topology structure of three sets of fuel cells and one set of energy storage batteries in parallel,a simulation model is built based on Matlab/Simulink software.Research the composition mechanism and operating principle of fuel cell and lithium battery,establish fuel cell,lithium battery and its one-way and two-way DC/DC converter models respectively,and build a set of simulation models of multi-stack fuel cell hybrid power system,and based on this model identifies the polarization characteristic curve and power efficiency curve of the fuel cell.Next,this paper proposes a hierarchical energy management method for multi-stack hybrid power systems that considers consistent stack performance.At the local level,through the study of virtual droop control and the performance consistency of multi-stack fuel cells,an adaptive multi-stack fuel cell power allocation method considering the operating performance of the stack is proposed;at the global level,based on the traditional energy management strategy Based on the analysis and improvement,an improvement strategy with the smallest equivalent hydrogen consumption is proposed.And based on the research of global and local energy management strategies,two other hierarchical energy management strategies are proposed to compare and analyze the simulation results.Finally,the three proposed hierarchical energy management methods were simulated and verified on the RT-LAB hardware-in-the-loop simulation platform,and the three methods were respectively carried out on power,efficiency,voltage,current,SOC,hydrogen consumption and other aspects.Comparison of the three methods,analysis of the characteristics and application of the three methods.The experimental results show that the three hierarchical energy management methods are effective and feasible,but the hierarchical strategy proposed in this paper considering the consistent stack performance improves the overall system efficiency,reduces hydrogen consumption,optimizes fuel cell operating performance,and manages lithium batteries SOC and other aspects are better than the other two strategies.