Projects:2021s2-63531 Utility-scale vanadium flow battery in South Australia: System, data and performance analysis

Abstract here

Introduction

South Australia is a unique “living laboratory” where remarkable levels of renewable energy penetration exist (100% instant renewable source, even with curtailment) while conventional coal power stations are decommissioned. However, we have also experienced significant negative impacts during this energy transition, which include state-wide blackout, negative power flow both in distribution and transmission lines, poor power quality, and controlled switching of the smart inverters in a Virtual Power Plant (VPP) structures. In 2020, Yadlamalka Energy Pty Ltd has obtained significant funding from the Australian Renewable Energy Agency (ARENA) to solve some of the issues in the power grid using a battery storage system. The project will have a 2 MW / 8 MWh utility-scale vanadium flow battery near Hawker in South Australia. The vanadium battery is supplied by Invinity Energy Systems and a 6 MW solar PV array on land held by the Yadlamalka Land Trust Neuroodla, adjacent to Yadlamalka Station. The battery system will connect to the National Electricity Market (NEM) to demonstrate the potential for grid-connected vanadium flow batteries to provide energy and frequency control ancillary services (FCAS). The construction has already started and the system will be commissioned by the end of 2021. In this project, the project team will analyze the system first (including PV, vanadium battery, converters, control, environment, grid, and load) and then develop methodologies for performance analysis after the system is operational and electrical and environmental data becomes available.

Project team

Project students

• Alan(Wenjun) Xie

Supervisors

• Nesimi Ertugrul
• Nelson Tansu
• Andrew Watson (Yadlamalka Energy Pty Ltd)

Objectives

The project aims to design a comprehensive VFBESS model set for power analysis and energy analysis in terms of both battery and systematic. This will be achieved by projects team 1 & team 2. The aim of project team one is to (1) Compare the existing flow batteries technologies, and understand the key parameters in BESS evaluation; (2) Understanding Vanadium Flow Battery components, working principles, advantages, and limitations; (3) Compare existing cell-level VFB models and modeling platforms; (4) Develop a comprehensive electrical circuit model for VFB cell; (5) Applying model with available data and verifying the results with existing test results; (6) Simulating Vanadium Battery cell model with general parallel connection and finding characteristics of VFB cell; (7) Providing an overview of the Yadlamalka Vanadium Flow Battery System and suggesting a direction for future works

Utiltiy-scale Battery Technologies Comparison

[1-5]

Table 1 evaluates the existing utility-scale battery technologies in terms of the main characteristics of the battery. The outstanding items for each characteristic are highlighted in green colors. The response time represents how fast the battery can switch from charge to discharge, and a fast response is essential for providing Frequency Control Ancillary Service (FCAS) because the grid will need rapid charge or discharge to maintain the voltage stability when it is necessary. Depth of discharge (DoD) is the opposite of the State of Charge (SOC), achieved by 1-SOC [1]. Maximum DoD indicates how much energy can be cycled into or out of the battery without compromising its efficiency or damaging the battery's health. The lifetime of the battery is evaluated in the units of charge-to-discharge cycles. Power density and Energy density are key parameters paired with a cost-effective battery in the large-scale commercial battery. It represents the amount of power or energy in a given mass (or volume), which is various for different battery materials and layouts [1]. Maturity and flexibility are related to the application level of the battery technologies [2]. The self-discharge is how much internal charge reduction in the battery without connection between the electrodes or external circuit [1]. Round-trip efficiency is associated with the difference between energy cycled in and energy cycled out, which depends on the loss of operating the entire battery system [1]. As table 1 shown, despite the fact that full flow battery has the disadvantages of its low energy density and power density, it is still the ideal solution for utility-scale battery in the power grid as its capability of 100% discharge, long life cycle, and high safety rating. Full flow battery technology, as a relatively new technology, is an opportunity requiring more attention and further research investigations.

Model type comparison

[6-8]

Method and Model

Simulation Result

Conclusion

Through the literature research, existing utility-scale battery technologies have been compared. Vanadium flow batteries are selected with justified reasons for utility-scale batteries. Further study is developing the vanadium flow battery model with the selected model type, which enhances the understanding of the VFB characteristics. Based on the electrochemical reaction process of VFB, the equivalent circuit model of VRB is obtained; after analyzing the relationship of various parameters in the equivalent circuit model, a mathematical model of the VFB system is established; through the mathematical model, based on MATLAB/Simulink, a Simulation model of VRB. Through a VFB example with a rated power of 3.3kW and a rated capacity of 9.9kWh, under the constant charge-discharge model, the state of charge and charge-discharge characteristics of the VRB are simulated and studied in detail, and the simulation model is established correctly. The relationship between pump flow rate and SOC is observed. Based on the understanding of the battery behaviors from research and modeling, battery management suggestions are shared in the thesis regarding the Yadlamalka Vanadium Flow Battery system in terms of temperature, pump loss, and battery system control.

Future Work

Building a VRB equivalent circuit model requires a trade-off between model accuracy and complexity. First, the circuit model must be able to accurately reflect the VRB's input and output volt-ampere characteristics, SOC, loss of energy consumption, and dynamic response speed. Secondly, the VRB model must choose an appropriate simulation time. If the model is too accurate, the model complexity will be high, which will lead to too long a simulation time, which is not conducive to the simulation research of the system. Therefore, in order to simplify the research, this model development does not consider the influence of the VRB electrolyte vanadium ion concentration and the change of the electrolyte flow speed on the VRB charge and discharge. However, it is practical as the flow speed should not be static in reality. Hence, it is a direction for model improvement. Temperature factor T in the stack voltage estimator is the only factor in the developed battery model, but the heat exchanger and other heat sources should also be considered in the battery model as the high temperature might result in vanadium precipitation. It is worthy to develop a thermal model for VFB considering the ambient temperature and all other heat transferred from the power electronics in the VFB system. Besides, for optimizing the battery performance, the stack voltage-controlled method should be applied to the VFB for Utility-scale usage.

References

[1] Adb.org, 2022. [Online]. Available: https://www.adb.org/sites/default/files/publication/479891/handbook-battery-energy-storage-system.pdf. [Accessed: 03- Jun- 2022]. [2] "Progress in Flow Battery Research and Development", Iopscience.iop.org, 2022. [Online]. Available: https://iopscience.iop.org/article/10.1149/1.3599565/pdf. [Accessed: 03- Feb- 2022]. [3] X. Fan and B. Liu, “Battery Technologies for Grid Level Large Scale Electrical Energy Storage,” springer.com, Jan. 08, 2020. https://link.springer.com/content/pdf/10.1007/s12209-019-00231-w.pdf. [Accessed: 01- Feb- 2022]. [4] G. May, A. Davidson and B. Monahov, "Lead batteries for utility energy storage: A review", 2022. [Online]. Available: https://www.sciencedirect.com/science/article/pii/S2352152X17304437. [Accessed: 03- Mar- 2022]. [5] E. (EESI), "Fact Sheet | Energy Storage (2019) | White Papers | EESI", Eesi.org, 2022. [Online]. Available: https://www.eesi.org/papers/view/energy-storage-2019. [Accessed: 10- Mar- 2022]. [6] B. Xiong et al., “An Enhanced Equivalent Circuit Model of Vanadium Redox Flow Battery Energy Storage Systems Considering Thermal Effects,” IEEE Access, vol. 7, no. 8894042, pp. 162297–162308, 2019, doi: 10.1109/ACCESS.2019.2952212. [Accessed: 2-Sep-2021]. [7] Y. R. Challapuram, G. M. Quintero, S. B. Bayne, A. S. Subburaj, and M. A. Harral, “Electrical Equivalent Model of Vanadium Redox Flow Battery,” IEEE Xplore, Apr. 01, 2019. https://ieeexplore.ieee.org/document/8767145 [accessed Jun. 03, 2022]. [8] O. Akeyo, V. Rallabandi, N. Jewell, and D. M. Ionel, “Modeling and Simulation of a Utility-Scale Battery Energy Storage System,” IEEE Xplore, Aug. 01, 2019. https://ieeexplore.ieee.org/document/8974042 [accessed Jun. 03, 2022].