Analysis of Power Tracking Management Strategy for Fuel Cell Hybrid System

In order to improve the economical efficiency of the fuel cell hybrid system, the parameters and the adjustment method of state of charge (SOC) in the power following energy management strategy were analyzed, based on the fuel cell hydrogen consumption and the power fluctuation rate. The power fluctuation rate of the fuel cell was defined. Based on the fuel cell-supercapacitor hybrid system model established in the simulation software ADVISOR, the hydrogen consumption and the fluctuation rate were estimated under different SOC limits and charging power parameters. The two methods to adjust SOC , namely the Z-curve and the proportional integral (PI) adjustment , were designed. The hydrogen consumption and the fluctuation rate were compared in the different methods.The results show that the more the lower limit of SOC increases, the more the hydrogen consumption and the fluctuation rate are produced. The hydrogen consumption with the lower limit of SOC 0.5 is more 7.10% than one with 0.25, and its fluctuation rate increases by 3.85%. When the upper limit of SOC increases from 0.75 to 0.95, the fluctuation rate decreases by 3.51%. The change of charging power parameter in a certain range produces a lower hydrogen consumption and a lower fluctuation rate. Among SOC regulation modes, the hydrogen consumption of the PI regulation method are optimal with initial SOC value in the interval [0.28, 0.52], and so is Z-curve method in the interval [0.75, 0.90].