Balanced Control Strategy of Distributed Energy Storage SOC Considering Line Impedance

doi:10.11930/j.issn.1004-9649.202311060

Abstract

Abstract:

Due to the uncertainty of distributed generation (DG) in islanding DC microgrids, it is necessary to add an energy storage unit for a supplement. In traditional droop control, the output current cannot be accurately distributed due to line impedance difference, which affects the balancing effect of the energy storage unit's state of charge (SOC). Besides, the convergence rate slows down as SOC decreases. Also, the influence of DG fluctuation on bus voltage is not considered. Therefore, an improved droop control strategy is proposed. By calculating the output current deviation, the authors introduce an integrator for the current deviation to eliminate the influence of the line impedance difference. Acceleration term and adaptive acceleration factor are also designed to increase the SOC balancing speed. When the DG fluctuates, the output current increment is adjusted to meet the load power balance and keep the voltage stable. The simulation results show that the SOC convergence error of the proposed control strategy is less than 0.1% when considering the line impedance. Convergence speed increases by 20% compared with the method referred, and the voltage drop is less than 3%.

Key words: DC microgrid, distributed energy storage unit, state of charge, improved droop control

Zhongran YAO, Liying SUN. Balanced Control Strategy of Distributed Energy Storage SOC Considering Line Impedance[J]. Electric Power, 2024, 57(9): 238-246.

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URL: https://www.electricpower.com.cn/EN/10.11930/j.issn.1004-9649.202311060

https://www.electricpower.com.cn/EN/Y2024/V57/I9/238

Figures/Tables 7

Fig.1 DC microgrid structure

Fig.2 DESU parallel equivalent circuit

Table 1 Simulation parameters

项目		参数
储能单元额定容量/(A·h)		1.5
SOC初值/%		80、75
线路阻抗R_L1、R_L2/Ω		1、1.5
空载电压U_ref /V		160
DG额定功率/kW		1.5
DG额定电流/A		9.5
直流母线额定电压/V		158
额定负荷功率/kW		3.3
k₁		5
k₂		0.75
k_P		3
b		0.5

Fig.3 SOC balancing effect with unequal line impedance

Fig.4 SOC balancing effect with equal line impedance

Fig.5 SOC balancing effect with DG fluctuation

Fig.6 SOC balancing effect during charging

References 24

1	MOHAMED Y A R I, EL-SAADANY E F. Adaptive decentralized droop controller to preserve power sharing stability of paralleled inverters in distributed generation microgrids[J]. IEEE Transactions on Power Electronics, 2008, 23 (6): 2806- 2816. DOI
2	彭寒梅, 曹一家, 黄小庆. 对等控制孤岛微电网的静态安全风险评估[J]. 中国电机工程学报, 2016, 36 (18): 4837- 4846, 5107.
	PENG Hanmei, CAO Yijia, HUANG Xiaoqing. Static security risk assessment of islanded microgrids under peer-peer control[J]. Proceedings of the CSEE, 2016, 36 (18): 4837- 4846, 5107.
3	孙佳航, 王小华, 黄景光, 等. 基于MPC-VSG的孤岛微电网频率和电压动态稳定控制策略[J]. 中国电力, 2023, 56 (6): 51- 60, 81.
	SUN Jiahang, WANG Xiaohua, HUANG Jingguang, et al. MPC-VSG based control strategy for dynamic stability of frequency and voltage in islanded microgrid[J]. Electric Power, 2023, 56 (6): 51- 60, 81.
4	郝少飞, 邹文进, 葛浩然, 等. 基于改进鲸鱼优化算法的微电网优化运行[J]. 广东电力, 2022, 35 (1): 51- 59.
	HAO Shaofei, ZOU Wenjin, GE Haoran, et al. Optimizing operation of microgrid based on improved whale optimization algorithm[J]. Guangdong Electric Power, 2022, 35 (1): 51- 59.
5	霍龙, 张誉宝, 陈欣. 人工智能在分布式储能技术中的应用[J]. 发电技术, 2022, 43 (5): 707- 717.
	HUO Long, ZHANG Yubao, CHEN Xin. Artificial intelligence applications in distributed energy storage technologies[J]. Power Generation Technology, 2022, 43 (5): 707- 717.
6	许丹莉, 顾慧杰, 何宇斌, 等. 端对端交易-云储能市场的非合作联合博弈出清模型[J]. 南方电网技术, 2024, 18 (1): 85- 93.
	XU Danli, GU Huijie, HE Yubin, et al. Non-cooperative joint game clearing model of peer-to-peer transaction and cloud energy stroage market[J]. Southern Power System Technology, 2024, 18 (1): 85- 93.
7	邓诗蕾, 王明渝. 直流微电网潮流控制器与分布式储能协同控制策略[J]. 电力系统保护与控制, 2018, 46 (24): 40- 46.
	DENG Shilei, WANG Mingyu. Cooperative control strategy of DC microgrid power flow controller and distributed energy storage system[J]. Power System Protection and Control, 2018, 46 (24): 40- 46.
8	张静炜, 朱想, 赫卫国, 等. 考虑光伏发电和储能系统调压能力的配电网储能容量优化配置[J]. 广东电力, 2018, 31 (7): 30- 35. DOI
	ZHANG Jingwei, ZHU Xiang, HE Weiguo, et al. Optimized configuration for ESS capacity of distribution network considering voltage regulation ability of photovoltaic generation and ESS[J]. Guangdong Electric Power, 2018, 31 (7): 30- 35. DOI
9	MOKHTAR M, MAREI M I, EL-SATTAR A A. An adaptive droop control scheme for DC microgrids integrating sliding mode voltage and current controlled boost converters[J]. IEEE Transactions on Smart Grid, 2019, 10 (2): 1685- 1693. DOI
10	袁娜娜, 王允建, 张君, 等. 直流微网中基于SOC的改进下垂控制[J]. 电力系统保护与控制, 2019, 47 (15): 17- 23.
	YUAN Nana, WANG Yunjian, ZHANG Jun, et al. Improved droop control based on SOC in DC microgrid[J]. Power System Protection and Control, 2019, 47 (15): 17- 23.
11	郭昆丽, 付建哲, 闫东, 等. 考虑不同容量的储能单元荷电状态均衡研究[J]. 电源技术, 2021, 45 (9): 1202- 1204, 1226. DOI
	GUO Kunli, FU Jianzhe, YAN Dong, et al. Research on state of charge balance of energy storage units considering different capacity[J]. Chinese Journal of Power Sources, 2021, 45 (9): 1202- 1204, 1226. DOI
12	郑丽君, 王子鹏, 吕世轩, 等. 基于荷电状态的直流微电网中多储能分级运行控制方法[J]. 电网技术, 2021, 45 (3): 1006- 1015.
	ZHENG Lijun, WANG Zipeng, LÜ Shixuan, et al. Hierarchical operation control of multi-energy storage in DC microgrid based on state of charge[J]. Power System Technology, 2021, 45 (3): 1006- 1015.
13	朱珊珊, 汪飞, 郭慧, 等. 直流微电网下垂控制技术研究综述[J]. 中国电机工程学报, 2018, 38 (1): 72- 84, 344.
	ZHU Shanshan, WANG Fei, GUO Hui, et al. Overview of droop control in DC microgrid[J]. Proceedings of the CSEE, 2018, 38 (1): 72- 84, 344.
14	韦佐霖, 陈民铀, 李杰, 等. 孤岛微网中分布式储能SOC和效率均衡控制策略[J]. 电力自动化设备, 2018, 38 (4): 169- 177.
	WEI Zuolin, CHEN Minyou, LI Jie, et al. Balancing control strategy of SOC and efficiency for distributed energy storage in islanded microgrid[J]. Electric Power Automation Equipment, 2018, 38 (4): 169- 177.
15	XU D Z, XU A J, YANG C S, et al. A novel double-quadrant SoC consistent adaptive droop control in DC microgrids[J]. IEEE Transactions on Circuits and Systems II: Express Briefs, 2020, 67 (10): 2034- 2038.
16	OLIVEIRA T R, GONÇALVES SILVA W W A, DONOSO-GARCIA P F. Distributed secondary level control for energy storage management in DC microgrids[J]. IEEE Transactions on Smart Grid, 2017, 8 (6): 2597- 2607. DOI
17	米阳, 蔡杭谊, 袁明瀚, 等. 直流微电网分布式储能系统电流负荷动态分配方法[J]. 电力自动化设备, 2019, 39 (10): 17- 23.
	MI Yang, CAI Hangyi, YUAN Minghan, et al. Dynamic distribution method of current load for distributed energy storage system in DC microgrid[J]. Electric Power Automation Equipment, 2019, 39 (10): 17- 23.
18	刘勇, 雷延科, 盘宏斌. 一种直流微电网无母线电压偏移的均衡控制策略[J]. 电力系统保护与控制, 2020, 48 (12): 154- 161.
	LIU Yong, LEI Yanke, PAN Hongbin. A balancing control strategy for DC microgrid without bus voltage offset[J]. Power System Protection and Control, 2020, 48 (12): 154- 161.
19	李鹏程, 张纯江, 袁然然, 等. 改进SOC下垂控制的分布式储能系统负荷电流分配方法[J]. 中国电机工程学报, 2017, 37 (13): 3746- 3754.
	LI Pengcheng, ZHANG Chunjiang, YUAN Ranran, et al. Load current sharing method of distributed energy storage systems by improved SOC drooping control[J]. Proceedings of the CSEE, 2017, 37 (13): 3746- 3754.
20	米阳, 纪宏澎, 何星瑭, 等. 多储能独立直流微电网自适应分级协调控制[J]. 中国电机工程学报, 2018, 38 (7): 1980- 1989, 2213.
	MI Yang, JI Hongpeng, HE Xingtang, et al. Adaptive hierarchical coordinated control of multi-energy storage in isolated DC microgrid[J]. Proceedings of the CSEE, 2018, 38 (7): 1980- 1989, 2213.
21	柴秀慧, 张纯江, 柴建国, 等. 改进互联通信荷电状态下垂控制及功率均衡优化[J]. 电工技术学报, 2021, 36 (16): 3365- 3374.
	CHAI Xiuhui, ZHANG Chunjiang, CHAI Jianguo, et al. Improved interconnected communication state of charge droop control and power balance optimization[J]. Transactions of China Electrotechnical Society, 2021, 36 (16): 3365- 3374.
22	樊重阳, 何山. 电流精确分配的直流微网储能单元SOC均衡控制策略[J]. 安徽大学学报(自然科学版), 2022, 46 (3): 102- 108.
	FAN Chongyang, HE Shan. SOC balancing control strategy of energy storage unit in DC microgrid with accurate current distribution[J]. Journal of Anhui University (Natural Science Edition), 2022, 46 (3): 102- 108.
23	XU Y L, SHEN X W. Optimal control based energy management of multiple energy storage systems in a microgrid[J]. IEEE Access, 2018, 6, 32925- 32934. DOI
24	LU X N, SUN K, GUERRERO J M, et al. SoC-based droop method for distributed energy storage in DC microgrid applications[C]//2012 IEEE International Symposium on Industrial Electronics. Hangzhou, China. IEEE, 2012: 1640–1645.

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