Abstract

This paper builds the equivalent circuit model for a single cell of zinc nickel single flow battery (ZNB) with 300 Ah. According to the experimental data of the single cell under 100 A pulse discharge conditions, the model parameters can be obtained by parameter identification, and the analytical expressions for each model parameter can be obtained by using the method of high degree polynomial fitting and exponential function fitting, then the mathematical model of the stack voltage can be built. The relative error of the simulation results for stack voltage is controlled within 3.2% by experimental comparison, which verifies the accuracy of the model and model parameters. The parameter formulas obtained by fitting method can effectively solve calculation problem of the battery parameters. And under 100 A constant-current discharge condition, the stack voltage of the battery is dropping relatively flat over about 110 minutes after loading current, and dropping dramatically within about 50 minutes at the end of discharge due to the increasing polarization.

Highlights

  • Flow battery is one of the research hotspots of energy storage battery

  • In order to simulate the variation of stack voltage for the battery using equivalent circuit model,[16] it is necessary to carry out the experiments as follows: 1) put the fully charged battery idling for 10 minutes, and collect the open circuit voltage data; 2) discharge the battery for 1 minute with 100 A constant-current, and collect the stack voltage data; 3) put the battery idling for 5 minutes, and collect the stack voltage data; 4) cycle steps 2) and 3) until the battery reaches the cut-off discharge voltage

  • Based on the dynamic characteristics of the discharge curve and the idle curve for one certain pulse process, this paper analyzes the circuit equivalent mechanism of the battery during discharge, and the mathematical model of the stack voltage is built according to the pulse experimental data of a 300 Ah single cell

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Summary

INTRODUCTION

Flow battery is one of the research hotspots of energy storage battery. Compared with the internal resistance model, the Thevenin model considers dynamic characteristics under the operation condition and static characteristics under the idle condition of battery.[13] The PNGV model is limited by the simulation accuracy of battery capacity, running time and the nonlinear relationship between open circuit voltage and state of charge (SOC).[14,15] The goal of this paper is to build equivalent circuit model of ZNB, identify model parameters and obtain the simulation curve of the stack voltage of ZNB. This paper builds the equivalent circuit model of the battery, obtains the model parameters through pulse experiment, and establishes the mathematical model of stack voltage for the battery during discharge by using fitting method. With a view to solving the calculation problem of parameters through the parameter formulas, and laying the foundation for the further improvement and application of the simulation model of ZNB

Working principle of ZNB
Pulse experiment
Equivalent circuit model
Parameter identification
AND DISCUSSION
CONCLUSIONS

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