锌镍单液流电池外特性建模与性能分析

发布时间：2018-04-11 01:11

本文选题：锌镍单液流电池 + 改进Thevenin模型　；参考：《江苏科技大学》2017年硕士论文

【摘要】：风电、太阳能电池以及电网对大规模蓄电设施需求的增长为液流电池开拓了应用前景。防化研究院提出的锌镍单液流电池,以氧化镍电极为正极、沉积/溶解型锌电极为负极、碱性锌酸盐溶液为电解质,具有成本低、结构简单、循环寿命长等优点,为规模储能的发展和应用提供了一个高性价比的解决方案。本文在通过锌镍单液流电池电化学模型、Thevenin等效电路模型以及改进Thevenin模型的建立,寻找能够真实反映锌镍单液流电池外特性动态变化的最佳模型,为锌镍单液流电池的性能研究以及仿真模型进一步应用奠定基础。本文主要研究工作如下:(1)基于锌镍单液流电池工作原理,本文首先通过电池的能斯特方程和电解液循环系统建立了电池的电化学模型和机械模型,分析了电解液流量对电池性能的影响,并以额定充放电容量为216 Ah的单体电池为例,在恒流充放电模式下进行仿真并得出结果。仿真结果与实验结果能较好地吻合,但仍存在一定误差。(2)基于锌镍单液流电池的电压关系,建立了单体电池额定容量为300Ah的Thevenin模型。根据锌镍单液流电池100A脉冲放电实验数据,通过参数辨识得到Thevenin模型参数,再采用高次多项式和指数函数拟合的方法得到各模型参数的解析式,构建了锌镍单液流电池端电压的数学模型。经实验对比电池放电过程端电压仿真结果的相对误差控制在3.2%以内。(3)基于Thevenin模型与锌镍单液流电池电化学机理分析,把电池由双电层产生的电化学极化和由扩散产生的浓差极化分别采用RC并联电路进行等效,提出了改进的Thevenin等效电路模型。辨识模型参数后,通过离散化手段得到改进模型中各电压离散数学模型,并在MATLAB/Simulink环境中搭建仿真模型。经实验对比,100 A恒流放电条件下锌镍单液流电池Thevenin模型端电压仿真值最大相对误差为5.2%,而改进模型端电压仿真值最大相对误差为2.38%,并且改进模型端电压相对误差在整个放电过程中都低于Thevenin模型,说明改进模型准确度更高,对电池恒流放电端电压的预测更为准确。
[Abstract]:The growth of wind power, solar cells and power grid for large-scale storage facilities opens up the application prospects for liquid-flow batteries.Using nickel oxide electrode as positive electrode, depositing / dissolving zinc electrode as negative electrode and alkaline zinc salt solution as electrolyte, the single liquid zinc-nickel battery proposed by the Institute of Chemical Protection has the advantages of low cost, simple structure and long cycle life.It provides a high cost-performance solution for the development and application of scale energy storage.In this paper, through the electrochemical model of zinc nickel single liquid flow cell and the establishment of the Thevenin equivalent circuit model and the improved Thevenin model, the best model which can truly reflect the dynamic change of the external characteristics of the zinc nickel single liquid flow cell is found.It lays a foundation for the study of the performance of zinc-nickel single flow battery and the further application of simulation model.The main work of this paper is as follows: (1) based on the working principle of zinc nickel single flow battery, the electrochemical and mechanical models of the battery are established by the Nernst equation of the battery and the electrolyte circulation system.The effect of electrolyte flow rate on the performance of the battery was analyzed. Taking a single cell with a rated charge and discharge capacity of 216 Ah as an example, the simulation was carried out under the constant current charging and discharging mode and the results were obtained.The simulation results are in good agreement with the experimental results, but there is still a certain error. (2) based on the voltage relationship of the zinc-nickel single flow battery, the Thevenin model of the single cell with rated capacity of 300Ah is established.According to the experimental data of 100A pulse discharge of zinc-nickel single liquid flow battery, the parameters of Thevenin model are obtained by parameter identification, and the analytical expressions of each model parameter are obtained by the method of high order polynomial and exponential function fitting.A mathematical model of the terminal voltage of zinc nickel single flow battery was established.Based on Thevenin model and electrochemistry mechanism analysis of zinc nickel single flow battery, the relative error of the simulation results of terminal voltage during discharge is controlled within 3.2%.The electrochemical polarization produced by the double layer and the concentration polarization caused by diffusion are equivalent to the RC parallel circuit, and the improved Thevenin equivalent circuit model is proposed.After identifying the parameters of the model, the discrete mathematical model of each voltage in the improved model is obtained by means of discretization, and the simulation model is built in the MATLAB/Simulink environment.The maximum relative error of the simulation value of the Thevenin model voltage of Zn-Ni single flow battery under constant current discharge condition is 5.2and the maximum relative error of the modified model voltage simulation value is 2.38, and the relative error of the model terminal voltage is improved.During the whole discharge process, it is lower than the Thevenin model.It shows that the improved model has higher accuracy and more accurate prediction of battery constant current discharge terminal voltage.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM912

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