|
|
|
| Real-Time SOC Correction and Frequency Control Method for LFP Batteries Considering Ambient Temperature |
| Yu Jie1,2, Liao Siyang1,2, Xu Jian1,2, Yang Canran1,2, Wang Xinying3 |
1. Hubei Engineering and Technology Research Center for AC/DC Intelligent Distribution Network Wuhan 430072 China;
2. School of Electrical Engineering and Automation Wuhan University Wuhan 430072 China;
3. China Electric Power Research Institute Beijing 100192 China |
|
|
|
Abstract Lithium iron phosphate (LFP) batteries occupy an important position in the field of energy storage system (ESS) because of their excellent charge and discharge performance, better safety and cycle life. Temperature is an important factor in the application of LFP, affecting the capacity and material activity of LFP under operating conditions. The physical model of ESS involved in system frequency control is often based on conventional model data. However, the traditional mechanism model analysis and optimal control methods are difficult to meet the requirements of actual system. Therefore, this paper proposes a real-time correction method of model parameters based on environmental temperature correlation when ESS is involved in system frequency control, which can estimate the SOC of ESS more accurately and improve the reliability of frequency control.
Firstly, the mechanism analysis of temperature on the performance parameters of LFP is developed, focusing on the reasons for the impact of high and low temperature on the actual capacity and charging/discharging efficiency of the battery. Secondly, based on the actual test data provided by the manufacturer, the temperature coefficient and coulomb correlation coefficient are used to correct the actual capacity and efficiency, followed by real-time correction of the SOC in battery operation. Subsequently, the time-varying droop control method of the ESS considering the corrected SOC is studied to provide fast frequency support. The SOC considering environmental factors during actual operation will be different from the SOC without considering the extreme temperature, which will also affect the arrival time of the high and low alert positions in the operation state, thus affecting the battery discharge. By making real-time corrections to the SOC, the accuracy of ESS participation in system frequency regulation can be improved.
The improved IEEE13 node simulation results show that: under the step disturbance of the system by the sudden change of load, the SOC of ESS is always in the normal range within 1 000 s without considering the environment (T=25℃), the ESS always participates in system regulation, and the droop coefficient Kf_d is in a higher position due to the higher SOC, the frequency drops slowly, and the frequency regulation is better. However, high temperature (T=45℃) will lead to faster SOC decline and carry Kf_d to decrease rapidly, and the frequency regulation effect is reduced. In addition, the battery enters the low alert state near 855s, when the ESS cannot discharge for frequency control, that is, high temperature leads to the ESS to end regulation faster. Low temperature scenario (T =-10 ℃), discharge rate becomes slower, the frequency regulation effect is slightly higher than the normal temperature, and will be discharged for a longer time to participate in frequency regulation; the system is subject to extreme fluctuations in PV, the ESS has a fast response characteristics, can cooperate with the diesel to smooth out the fluctuations in PV power. The frequency regulation effect of the three ambient temperatures in the pre-disturbance period is not exactly the same, where the high temperature condition will have a smaller Kf_c due to a slightly higher SOC than the other two conditions, so the frequency regulation effect is worse and the frequency offset is larger. Besides, in the late stage of PV power fluctuation, the high temperature condition enters the high alert position at 1 738s, after which the ESS cannot continue charging thus exiting the frequency control. That is, high temperature prompted the ESS to withdraw from frequency control as soon as possible, and subsequently the system can only be supported by the diesel. The ESS under normal temperature will exit at 2 118 s, and the low temperature can all participate in frequency control within that 2 750 s.
From the simulation analysis, the frequency control method of the ESS proposed can effectively estimate the SOC more accurately for extreme weather conditions after considering the environmental temperature factor and making the frequency control effect more suitable for the actual operation scenario, and improve the efficiency and reliability of ESS participation in system frequency control. The method in this paper can estimate the SOC of ESS more accurately and improve the efficiency of frequency control compared to that without considering the environmental temperature factor.
|
|
Received: 13 January 2023
|
|
|
|
|
|
[1] 国家发展和改革委员会. 能源生产和消费革命战略[EB/OL](2016-2030). https://www.ndrc.gov.cn/fggz/ fzzlgh/gjjzxgh/201705/t20170517_1196767.html?code=&state=123,2017-05-17.
[2] 潘超, 范宫博, 王锦鹏, 等. 灵活性资源参与的电热综合能源系统低碳优化[J]. 电工技术学报, 2023, 38(6): 1633-1647.
Pan Chao, Fan Gongbo, Wang Jinpeng, et al.Low-carbon optimization of electric and heating integrated energy system with flexible resource participation[J]. Transactions of China Electrotechnical Society, 2023, 38(6): 1633-1647.
[3] 国家能源局. 2019年风电并网运行情况[EB/OL]. (2020-02-28)http://www.nea.gov.cn/2020-02/28/c_ 138827910.htm.
[4] 刘其辉, 逄思敏, 吴林林, 等. 大规模风电汇集系统电压不平衡机理、因素及影响规律[J]. 电工技术学报, 2022, 37(21): 5435-5450.
Liu Qihui, Pang Simin, Wu Linlin, et al.The mechanism, factors and influence rules of voltage imbalance in wind power integration areas[J]. Transactions of China Electrotechnical Society, 2022, 37(21): 5435-5450.
[5] Shi Zhaodi, Wang Weisheng, Huang Yuehui, et al.Simultaneous optimization of renewable energy and energy storage capacity with the hierarchical control[J]. CSEE Journal of Power and Energy Systems, 2020, 8(1): 95-104.
[6] Sioshansi R, Denholm P, Arteaga J, et al.Energy-storage modeling: state-of-the-art and future research directions[J]. IEEE Transactions on Power Systems, 2022, 37(2): 860-875.
[7] 孙冰莹, 杨水丽, 刘宗歧, 等. 国内外兆瓦级储能调频示范应用现状分析与启示[J]. 电力系统自动化, 2017, 41(11): 8-16, 38.
Sun Bingying, Yang Shuili, Liu Zongqi, et al.Analysis on present application of megawatt-scale energy storage in frequency regulation and its enlightenment[J]. Automation of Electric Power Systems, 2017, 41(11): 8-16, 38.
[8] 程瑜, 陈熙. 基于源-荷-储互动的储能对风电消纳能力影响分析[J]. 电力系统自动化, 2022, 46(13): 84-93.
Cheng Yu, Chen Xi.Analysis on influence of energy storage on accommodation capability of wind power based on source-load-storage interaction[J]. Automation of Electric Power Systems, 2022, 46(13): 84-93.
[9] Chang Minghui, Huang Hanpang, Chang Shuwei.A new state of charge estimation method for LiFePO4 battery packs used in robots[J]. Energies, 2013, 6(4): 2007-2030.
[10] Zhong Liang, Zhang Chenbin, He Yao, et al.A method for the estimation of the battery pack state of charge based on in-pack cells uniformity analysis[J]. Applied Energy, 2014, 113: 558-564.
[11] 李哲. 纯电动汽车磷酸铁锂电池性能研究[D]. 北京: 清华大学, 2011.
[12] 殷艳花, 窦银科, 左广宇, 等. 极地超低温环境下磷酸铁锂电池容量估计[J]. 电源技术, 2020, 44(5): 666-668.
Yin Yanhua, Dou Yinke, Zuo Guangyu, et al.Capacity estimation of lithium iron phosphate battery in polar ultra-low temperature environment[J]. Chinese Journal of Power Sources, 2020, 44(5): 666-668.
[13] 曹成荣. 考虑温度影响的磷酸铁锂电池建模及SOC估算研究[D]. 合肥: 合肥工业大学, 2017.
[14] 梅文昕, 段强领, 王青山, 等. 大型磷酸铁锂电池高温热失控模拟研究[J]. 储能科学与技术, 2021, 10(1): 202-209.
Mei Wenxin, Duan Qiangling, Wang Qingshan, et al.Thermal runaway simulation of large-scale lithium iron phosphate battery at elevated temperatures[J]. Energy Storage Science and Technology, 2021, 10(1): 202-209.
[15] Maleki H, Al Hallaj S, Selman J R, et al.Thermal properties of lithium-ion battery and components[J]. Journal of the Electrochemical Society, 1999, 146(3): 947-954.
[16] 王成山, 李琰, 彭克. 分布式电源并网逆变器典型控制方法综述[J]. 电力系统及其自动化学报, 2012, 24(2): 12-20.
Wang Chengshan, Li Yan, Peng Ke.Overview of typical control methods for grid-connected inverters of distributed generation[J]. Proceedings of the Chinese Society of Universities for Electric Power System and Its Automation, 2012, 24(2): 12-20.
[17] 李欣然, 户龙辉, 吕超贤, 等. 锂离子电池容量的预测建模及其仿真研究[J]. 系统仿真学报, 2014, 26(8): 1733-1740, 1746.
Li Xinran, Hu Longhui, Lü Chaoxian, et al.Research on lithium-ion battery capacity predictive modeling and its simulation[J]. Journal of System Simulation, 2014, 26(8): 1733-1740, 1746.
[18] 肖占龙, 郑岳久, 李相俊, 等. 变温下磷酸铁锂电池的SOC估计方法研究[J]. 电源学报, 2023:1-13[2023-02-17].
Xiao Zhanlong, Zheng Yuejiu, Li Xiangjun, et al. Study of SOC estimation method of LiFePO4 battery uder variable temperature [J]. Journal of Power Supply, 2023: 1-13 [2023-02-17].
[19] 吴立峰, 刘昊, 林仲钦, 等. 低温环境下锂离子电池荷电状态与超声透射飞行时间的关系研究[J]. 电工技术学报, 2022, 37(21): 5617-5626.
Wu Lifeng, Liu Hao, Lin Zhongqin, et al.Relationship between state of charge of lithium-ion battery and ultrasonic transmission flight time at low temperature[J]. Transactions of China Electrotechnical Society, 2022, 37(21): 5617-5626.
[20] Lee E S, Huq A, Manthiram A.Understanding the effect of synthesis temperature on the structural and electrochemical characteristics of layered-spinel composite cathodes for lithium-ion batteries[J]. Journal of Power Sources, 2013, 240: 193-203.
[21] Cho H M, Choi W S, Go J Y, et al.A study on time-dependent low temperature power performance of a lithium-ion battery[J]. Journal of Power Sources, 2012, 198: 273-280.
[22] 罗玲, 宋文吉, 林仕立, 等. 工作温度对磷酸铁锂电池SOC影响及研究进展[J]. 新能源进展, 2015, 3(1): 59-69.
Luo Ling, Song Wenji, Lin Shili, et al.Research progress on effects of temperature on SOC and its estimation for LFP battery[J]. Advances in New and Renewable Energy, 2015, 3(1): 59-69.
[23] 张彩萍, 张承宁, 李军求. 电传动装甲车辆用锂离子电池充放电特性[J]. 电源技术, 2010, 34(2): 109-112.
Zhang Caiping, Zhang Chengning, Li Junqiu.Charge and discharge characteristics of lithium-ion traction battery for electrical drive armored vehicles[J]. Chinese Journal of Power Sources, 2010, 34(2): 109-112.
[24] 张祺. 用于动力电池整包快速检测的容量估算方法研究[D]. 北京: 北京交通大学, 2020.
[25] 孙丙香, 任鹏博, 陈育哲, 等. 锂离子电池在不同区间下的衰退影响因素分析及任意区间的老化趋势预测[J]. 电工技术学报, 2021, 36(3): 666-674.
Sun Bingxiang, Ren Pengbo, Chen Yuzhe, et al.Analysis of influencing factors of degradation under different interval stress and prediction of aging trend in any interval for lithium-ion battery[J]. Transactions of China Electrotechnical Society, 2021, 36(3): 666-674.
[26] Yu Jie, Liao Siyang, Xu Jian.Frequency control strategy for coordinated energy storage system and flexible load in isolated power system[J]. Energy Reports, 2022, 8: 966-979.
[27] Acharya S, El Moursi M S, Al-Hinai A. Coordinated frequency control strategy for an islanded microgrid with demand side management capability[J]. IEEE Transactions on Energy Conversion, 2018, 33(2): 639-651.
[28] 国家质量监督检验检疫总局, 中国国家标准化管理委员会. GB/T 15945—2008 电能质量电力系统频率偏差[S]. 北京: 中国标准出版社, 2008. |
|
|
|
2023, Vol. 38 
