考虑不匹配线阻的分布式储能单元荷电状态均衡研究
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摘要
孤岛直流微电网中,分布式储能单元利用充放电以保证分布式能源出力和负荷波动时的电压稳定和能量平衡。然而,由于线路阻抗不匹配,导致各分布式储能单元必然会出现荷电状态差异,造成蓄电池过充电或过放电,缩短储能单元的使用寿命。为此,提出一种考虑不匹配线路阻抗的储能单元荷电状态均衡的改进下垂控制策略。该方法在传统下垂控制的基础上引入电流和荷电状态信息,利用中央控制器发出的同步信号触发采样保持器,根据采样周期自动修改下垂特性曲线的参考电压,从而可以克服线路阻抗对电流负荷分配的影响,同时能实现电流负荷在储能单元的合理分配,避免过充过放。最后,通过RTDS实验验证了所提控制策略的有效性和正确性。
In order to guarantee the voltage stability and power balance in the island DC microgrid, which is caused by the distributed energy output power or load fluctuation, it is necessary to take advantage of charge and discharge for distributed energy storage units(DESUs). Due to the difference of line impedance among DESUs, the state-of-charge of the DESUs may be unbalanced under the conventional droop control, which may lead to overcharging or over-discharging of DESUs and even shorten service life of battery. Therefore, an improved droop control strategy with unmatched line resistance was proposed. By introducing the information of current and state-of-charge to the conventional droop control, the synchronization signal was sent to trigger the sampling holder by the central controller, and automatically adjust the reference voltage of droop characteristic curve according to the sampling period. Therefore, the influence of line impedance on current load distribution can be removed, and the current can be reasonably distributed among DESUs to avoid overcharge and overdischarge. Finally, the effectiveness and correctness of the proposed control strategy is verified through the RTDS experiment.
In order to guarantee the voltage stability and power balance in the island DC microgrid, which is caused by the distributed energy output power or load fluctuation, it is necessary to take advantage of charge and discharge for distributed energy storage units(DESUs). Due to the difference of line impedance among DESUs, the state-of-charge of the DESUs may be unbalanced under the conventional droop control, which may lead to overcharging or over-discharging of DESUs and even shorten service life of battery. Therefore, an improved droop control strategy with unmatched line resistance was proposed. By introducing the information of current and state-of-charge to the conventional droop control, the synchronization signal was sent to trigger the sampling holder by the central controller, and automatically adjust the reference voltage of droop characteristic curve according to the sampling period. Therefore, the influence of line impedance on current load distribution can be removed, and the current can be reasonably distributed among DESUs to avoid overcharge and overdischarge. Finally, the effectiveness and correctness of the proposed control strategy is verified through the RTDS experiment.
引文
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[19]Ahn S J,Park J W,Chung I Y,et al.Power-sharing method of multiple distributed generators considering control modes and configurations of a microgrid[J].IEEETransactions on Power Delivery,2010,25(3):2007-2016.
[20]刘一欣,郭力,李霞林,等.基于实时数字仿真的微电网数模混合仿真实验平台[J].电工技术学报,2014,29(2):82-92.Liu Yixin,Guo Li,Li Xialin,et al.Real-time digital simulator based digital-analog hybrid simulation exprimental platform for a microgrid[J].Transactions of China Electrotechnical Society,2014,29(2):82-92(in Chinese).
[21]白建成.微网系统半实物仿真技术研究[D].北京:北京交通大学,2014.Bai Jiancheng.Power hardware in the loop simulation technology of microgrid[D].Beijing:Beijing Jiaotong University,2014(in Chinese).
[2]李霞林,郭力,王成山,等.直流微电网关键技术研究综述[J].中国电机工程学报,2016,36(1):2-17.Li Xialin,Guo Li,Wang Chengshan,et al.Key technologies of DC microgrids:an overview[J].Proceedings of the CSEE,2016,36(1):2-17(in Chinese).
[3]Liu X,Wang P,Loh P C.A hybrid AC/DC microgrid and its coordination control[J].IEEE Transactions on Smart Grid,2011,2(2):278-286.
[4]Cheng P T,Chen C A,Lee T L,et al.A Cooperative Imbalance Compensation Method for Distributed Generation Interface Converters[J].IEEE Transactions on Industry Applications,2009,45(2):805-815.
[5]谢玲玲,时斌,华国玉,等.基于改进下垂控制的分布式电源并联运行技术[J].电网技术,2013,37(4):992-998.Xie Lingling,Shi Bin,Hua Guoyu,et al.Parallel operation technology of distributed generations based on improved droop control[J].Power System Technology,2013,37(4):992-998(in Chinese).
[6]Venkatraman R,Khaitan S K.A survey of techniques for designing and managing microgrids[C]//2015 IEEE Power&Energy Society General Meeting.Denver:IEEE,2015:1-5.
[7]Nguyen N,Orugangmin S K,Na K,et al.An adaptive backward control battery lithium-ion battery[J].IEEETransactions on Vehicular Technology,2014,63(8):3651-3660.
[8]Huang W,Abu Qahouq J A.Energy sharing control scheme for state-of-charge balancing of distributed battery energy storage system[J].IEEE Transactions on Industrial Electronics,2015,62(5):2764-2776.
[9]杨捷,金新民,吴学智,等.一种适用于直流微电网的改进型电流负荷分配控制策略[J].中国电机工程学报,2016,36(1):59-67.Yang Jie,Jin Xinmin,Wu Xuezhi,et al.An improved load current sharing control method in DC microgrids[J].Proceedings of the CSEE,2016,36(1):59-67(in Chinese).
[10]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.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(in Chinese).
[11]Lu X,Sun K,Guerrero J M,et al.State-of-charge balance using adaptive droop control for distributed energy storage systems in DC microgrid applications[J].IEEETransactions on Industrial Electronics,2013,61(6):2804-2815.
[12]陆晓楠,孙凯,黄立培,等.直流微电网储能系统中带有母线电压跌落补偿功能的负荷功率动态分配方法[J].中国电机工程学报,2013,33(16):37-46.Lu Xiaonan,Sun Kai,Huang Lipei,et al.Dynamic load power sharing method with elimination of bus voltage deviation for energy storage systems in DC microgrids[J].Proceedings of the CSEE,2013,33(16):37-46(in Chinese).
[13]Lu X,Sun K,Guerrero J M,et al.Double-quadrant state-of-charge based droop control method for distributed energy storage systems in autonomous DC microgrids[J].IEEE Transactions on Smart Grid,2014,6(1):147-157.
[14]米阳,吴彦伟,纪宏澎,等.基于多组储能动态调节的独立直流微电网协调控制[J].电力自动化设备,2017(5):170-176.Mi Yang,Wu Yanwei,Ji Hongpeng,et al.Coordinative control based on dynamic load allocation among multiple energy storages for islanded DC microgrid[J].Electric Power Automation Equipment,2017,37(5):170-176(in Chinese).
[15]Diaz N L,Dragi?evi?T,Vasquez J C,et al.Intelligent distributed generation and storage units for DCmicrogrids-a new concept on cooperative control without communications beyond droop control[J].IEEETransactions on Smart Grid,2014,5(5):2476-2485.
[16]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.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(in Chinese).
[17]Morstyn T,Savkin A,Hredzak B,et al.Multi-agent sliding mode control for state of charge balancing between battery energy storage systems distributed in a DCmicrogrid[J].IEEE Transactions on Smart Grid,2018,9(5):4735-4743.
[18]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(in Chinese).
[19]Ahn S J,Park J W,Chung I Y,et al.Power-sharing method of multiple distributed generators considering control modes and configurations of a microgrid[J].IEEETransactions on Power Delivery,2010,25(3):2007-2016.
[20]刘一欣,郭力,李霞林,等.基于实时数字仿真的微电网数模混合仿真实验平台[J].电工技术学报,2014,29(2):82-92.Liu Yixin,Guo Li,Li Xialin,et al.Real-time digital simulator based digital-analog hybrid simulation exprimental platform for a microgrid[J].Transactions of China Electrotechnical Society,2014,29(2):82-92(in Chinese).
[21]白建成.微网系统半实物仿真技术研究[D].北京:北京交通大学,2014.Bai Jiancheng.Power hardware in the loop simulation technology of microgrid[D].Beijing:Beijing Jiaotong University,2014(in Chinese).