|
|
|
| Research on Active Damping Strategy Based on the Differentiation of Injected Grid Current Harmonics |
| Yang Shude1, Li Wang1, Xu Jia1, Zhang Xinwen2, Xiong Liansong3 |
1. College of Electrical, Energy and Power Engineering Yangzhou University Yangzhou 225127 China;
2. School of Electrical and Information Engineering North Minzu University Yinchuan 750021 China;
3. State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong University Xi'an 710049 China |
|
|
|
Abstract The active damping strategy that simulates a virtual resistor at the point of common coupling (PCC) is effective to improve the converter stability under weak grid. However, in the traditional strategy, the PCC voltage is generally fed to the current reference by multiplying a gain. Naturally, the disturbances of grid background harmonic voltages will be also introduced to the current reference, and the unexpected harmonics will arise in the current. Thus, the traditional strategy will weaken the rejection abilities of the converter on the background harmonic voltages and reduce the current quality. To solve these issues, this paper proposes an active damping strategy based on the differentiation of injected grid current harmonics, which can ensure the system stability and the current quality simultaneously.
First, the control structure of the active damping strategy based on the differentiation of injected grid current harmonics is given, in which the differential operation is used to transfer the harmonic currents to the harmonic voltages. This way, only the harmonic voltages caused by the unstable resonance will be fed to the output current reference, and the grid background harmonic voltages can be excluded. Therefore, the disturbances in the output current reference from grid background harmonic voltages can be eliminated and the output current quality will not be influenced by the active damping control. In addition, the rejection abilities of the converter on the background harmonic voltage disturbances before and after applying the proposed active damping strategy are compared.
Simulation and experimental results show that, with the proposed active damping strategy, the minimum short circuit ratio (SCR) for the grid-connected converter system to operate stably is reduced from 20 to 2.9, which indicates that the proposed method can markedly improve the adaptability of the converter to weak grid condition. Moreover, under a distorted grid voltage condition, the comparison of current total harmonic distortion (THD) with the different active damping methods shows that, the current THDs are 2.18% (simulation result) and 2.11% (experimental result) with the proposed method, while the current THDs are 3.3% (simulation result) and 3.0 (experimental result) with the conventional method. This demonstrates that the proposed active damping method can obtain higher current quality compared to the conventional method. This is because the rejection abilities of the converter on the background harmonic voltage disturbances can remain unchanged when the proposed active damping method is used.
The following conclusions can be drawn from the simulation and experimental analysis: (1) If the grid impedance is not considered, the larger grid inductance of weak grid may affect the converter stability and even to destabilize the system. (2) The active damping strategy based on PCC voltage feedback can improve the stability of the converter under weak grid. However, it will introduce the disturbances of background harmonic voltages to the current reference and weaken the rejection abilities of the converter on these disturbances, thereby reducing the current quality. (3) For the active damping strategy based on the differentiation of injected grid current harmonics, the differential operation is used to transfer the resonant current caused by the instability to the resonant voltage at PCC. Therefore, the disturbances in the current reference from background harmonic voltages can be avoided. The proposed method can realize the active damping performance, and meanwhile, the rejection abilities of the converter on the background harmonic voltages will not be weakened. Both the stability control of the converter system under weak grid and the high quality of grid-injected current can be satisfied.
|
|
Received: 11 August 2022
|
|
|
|
|
|
[1] 李龙源, 付瑞清, 吕晓琴, 等. 接入弱电网的同型机直驱风电场单机等值建模[J]. 电工技术学报, 2023, 38(3): 712-725.
Li Longyuan, Fu Ruiqing, Lü Xiaoqin, et al.Single machine equivalent modeling of weak grid connected wind farm with same type PMSGs[J]. Transactions of China Electrotechnical Society, 2023, 38(3): 712-725.
[2] 徐东坡, 代永恒, 姬成群, 等. 基于RTDS的光伏逆变器接入薄弱电网仿真测试及研究[J]. 电气技术, 2022, 23(3): 82-86.
Xu Dongpo, Dai Yongheng, Ji Chengqun, et al.Simulation test and study of photovoltaic inverter connected to weak power grid based on RTDS[J]. Electrical Engineering, 2022, 23(3): 82-86.
[3] 潘鹏宇, 胡海涛, 肖冬华, 等. 高速列车变流器“扫频式”dq阻抗测量中的频率耦合干扰机理及抑制策略[J]. 电工技术学报, 2022, 37(4): 990-999, 1009.
Pan Pengyu, Hu Haitao, Xiao Donghua, et al.Frequency coupling interference mechanism and suppression strategy for frequency-sweeping-based dq impedance measurement of high-speed train converter[J]. Transactions of China Electrotechnical Society, 2022, 37(4): 990-999, 1009.
[4] Agorreta J L, Borrega M, López J, et al.Modeling and control of N-paralleled grid-connected inverters with LCL filter coupled due to grid impedance in PV plants[J]. IEEE Transactions on Power Electronics, 2011, 26(3): 770-785.
[5] Wang Xiongfei, Blaabjerg F, Liserre M, et al.An active damper for stabilizing power-electronics-based AC systems[J]. IEEE Transactions on Power Electronics, 2014, 29(7): 3318-3329.
[6] 谢志为, 陈燕东, 伍文华, 等. 弱电网下多逆变器并网系统的全局高频振荡抑制方法[J]. 电工技术学报, 2020, 35(4): 885-895.
Xie Zhiwei, Chen Yandong, Wu Wenhua, et al.A global high-frequency oscillation suppression method for multi-inverter grid-connected system in weak grid[J]. Transactions of China Electrotechnical Society, 2020, 35(4): 885-895.
[7] 莫必祥, 伍文华, 陈燕东, 等. 抑制直驱风电并网系统次/超同步振荡的储能变流器有源阻尼控制方法[J]. 电网技术, 2023, 47(6): 2380-2390.
Mo Bixiang, Wu Wenhua, Chen Yandong, et al.Active damping control method for power conversion system to suppress sub-/super-synchronous oscillation of D-PMSG grid-connected system[J]. Power System Technology, 2023, 47(6): 2380-2390.
[8] Bai Haofeng, Wang Xiongfei, Loh P C, et al.Passivity enhancement of grid-tied converter by series LC-filtered active damper[C]//2015 IEEE Energy Conversion Congress and Exposition (ECCE), Montreal, QC, Canada, 2015: 5830-5837.
[9] 李云丰, 赵文广, 孔明, 等. 直驱风电场经柔直并网的虚拟并联阻抗次同步振荡抑制策略[J]. 中国电机工程学报, 2022, 42(17): 6326-6338.
Li Yunfeng, Zhao Wenguang, Kong Ming, et al.Virtual paralleled-impedance control strategy of flexible HVDC connecting to the PMSG-based wind farm for sub-synchronous oscillation suppression[J]. Proceedings of the CSEE, 2022, 42(17): 6326-6338.
[10] 姜齐荣, 王亮, 谢小荣. 电力电子化电力系统的振荡问题及其抑制措施研究[J]. 高电压技术, 2017, 43(4): 1057-1066.
Jiang Qirong, Wang Liang, Xie Xiaorong.Study on oscillations of power-electronized power system and their mitigation schemes[J]. High Voltage Engineering, 2017, 43(4): 1057-1066.
[11] 杨东升, 阮新波, 吴恒. 提高LCL型并网逆变器对弱电网适应能力的虚拟阻抗方法[J]. 中国电机工程学报, 2014, 34(15): 2327-2335.
Yang Dongsheng, Ruan Xinbo, Wu Heng.A virtual impedance method to improve the performance of LCL-type grid-connected inverters under weak grid conditions[J]. Proceedings of the CSEE, 2014, 34(15): 2327-2335.
[12] 陈杰, 章新颖, 闫震宇, 等. 基于虚拟阻抗的逆变器死区补偿及谐波电流抑制分析[J]. 电工技术学报, 2021, 36(8): 1671-1680.
Chen Jie, Zhang Xinying, Yan Zhenyu, et al.Dead-time effect and background grid-voltage harmonic suppression methods for inverters with virtual impedance control[J]. Transactions of China Electrotechnical Society, 2021, 36(8): 1671-1680.
[13] Jia Lei, Ruan Xinbo, Zhao Wenxin, et al.An adaptive active damper for improving the stability of grid-connected inverters under weak grid[J]. IEEE Transactions on Power Electronics, 2018, 33(11): 9561-9574.
[14] 马伟明. 关于电工学科前沿技术发展的若干思考[J]. 电工技术学报, 2021, 36(22): 4627-4636.
Ma Weiming.Thoughts on the development of frontier technology in electrical engineering[J]. Transactions of China Electrotechnical Society, 2021, 36(22): 4627-4636.
[15] 樊陈, 姚建国, 常乃超, 等. 电网宽频振荡实时监测技术方案[J]. 电力系统自动化, 2021, 45(11): 152-159.
Fan Chen, Yao Jianguo, Chang Naichao, et al.Technical scheme for real-time monitoring of wide-frequency oscillation in power grid[J]. Automation of Electric Power Systems, 2021, 45(11): 152-159.
[16] 孙东阳, 孟繁易, 王南, 等. 基于反步自适应准谐振控制的双馈风机次同步振荡抑制策略[J]. 电工技术学报, 2023, 38(9): 2375-2390.
Sun Dongyang, Meng Fanyi, Wang Nan, et al.DFIG sub-synchronous oscillation suppression strategy based on backstepping adaptive quasi-resonant control[J]. Transactions of China Electrotechnical Society, 2023, 38(9): 2375-2390.
[17] 杨苓, 陈燕东, 罗安, 等. 多机并网系统的两带阻滤波器高频振荡抑制方法[J]. 中国电机工程学报, 2019, 39(8): 2242-2252, 7.
Yang Ling, Chen Yandong, Luo An, et al.High-frequency oscillation suppression method by two notch filters for multi-inverter grid-connected system[J]. Proceedings of the CSEE, 2019, 39(8): 2242-2252, 7.
[18] 沈姝衡, 方天治, 章益凡. 高带宽数字控制LCL型并网逆变器及其提高并网系统鲁棒性的谐振抑制技术研究[J]. 电工技术学报, 2022, 37(21): 5548-5561.
Shen Shuheng, Fang Tianzhi, Zhang Yifan.A high-bandwidth digital-control LCL-type grid-tied inverter and resonance-suppressing technique for improving the robustness of grid-connected system[J]. Transactions of China Electrotechnical Society, 2022, 37(21): 5548-5561.
[19] 吴恒, 阮新波, 杨东升. 弱电网条件下锁相环对LCL型并网逆变器稳定性的影响研究及锁相环参数设计[J]. 中国电机工程学报, 2014, 34(30): 5259-5268.
Wu Heng, Ruan Xinbo, Yang Dongsheng.Research on the stability caused by phase-locked loop for LCL-type grid-connected inverter in weak grid condition[J]. Proceedings of the CSEE, 2014, 34(30): 5259-5268.
[20] Wen Bo, Boroyevich D, Burgos R, et al.Inverse nyquist stability criterion for grid-tied inverters[J]. IEEE Transactions on Power Electronics, 2017, 32(2): 1548-1556.
[21] Tang Yi, Yao Wenli, Loh P C, et al.Design of LCL-filters with LCL resonance frequencies beyond the Nyquist frequency for grid-connected inverters[C]// 2015 IEEE Energy Conversion Congress and Exposition (ECCE), Montreal, QC, Canada, 2015: 5137-5144.
[22] 鲍旭聪, 王晓琳, 顾聪, 等. 超高速永磁电机驱动系统电流环稳定性分析与改进设计[J]. 电工技术学报, 2022, 37(10): 2469-2480.
Bao Xucong, Wang Xiaolin, Gu Cong, et al.Stability analysis and improvement design of current loop of ultra-high-speed permanent magnet motor drive system[J]. Transactions of China Electrotechnical Society, 2022, 37(10): 2469-2480.
[23] Ji Chao, Zanchetta P, Carastro F, et al.Repetitive control for high-performance resonant pulsed power supply in radio frequency applications[J]. IEEE Transactions on Industry Applications, 2014, 50(4): 2660-2670.
[24] Abusara M, Sharkh S, Zanchetta P.Adaptive repetitive control with feedforward scheme for grid-connected inverters[J]. IET Power Electronics, 2015, 8(8): 1403-1410.
[25] 杨頔, 姚钢, 周荔丹. 功率变化环境下的四线制Vienna整流器优化联合控制方法[J]. 电工技术学报, 2021, 36(2): 305-319.
Yang Di, Yao Gang, Zhou Lidan.An improved control method of 4-wire Vienna rectifier considering power fluctuation[J]. Transactions of China Electrotechnical Society, 2021, 36(2): 305-319.
[26] Zhang Xuan, Wang F, Cao Wenchao, et al.Influence of voltage feed-forward control on small-signal stability of grid-tied inverters[C]//2015 IEEE Applied Power Electronics Conference and Exposition (APEC), Charlotte, NC, USA, 2015: 1216-1221.
[27] 胡寿松. 自动控制原理[M]. 6版. 北京: 科学出版社, 2013.
[28] 赵强松, 陈莎莎, 周晓宇, 等. 用于并网逆变器谐波抑制的重复-比例复合控制器分析与设计[J]. 电工技术学报, 2019, 34(24): 5189-5198.
Zhao Qiangsong, Chen Shasha, Zhou Xiaoyu, et al.Analysis and design of combination controller based on repetitive control and proportional control for harmonics suppression of grid-tied inverters[J]. Transactions of China Electrotechnical Society, 2019, 34(24): 5189-5198.
[29] 刘桂花, 曹小娇, 王卫. 弱电网下单相光伏并网逆变器锁频环同步方法[J]. 中国电机工程学报, 2015, 35(19): 5022-5029.
Liu Guihua, Cao Xiaojiao, Wang Wei.A frequency locked loop grid synchronization method of single-phase grid-connected PV inverter under weak grid[J]. Proceedings of the CSEE, 2015, 35(19): 5022-5029.
[30] 涂春鸣, 高家元, 赵晋斌, 等. 弱电网下具有定稳定裕度的并网逆变器阻抗重塑分析与设计[J]. 电工技术学报, 2020, 35(6): 1327-1335.
Tu Chunming, Gao Jiayuan, Zhao Jinbin, et al.Analysis and design of grid-connected inverter impedance remodeling with fixed stability margin in weak grid[J]. Transactions of China Electrotechnical Society, 2020, 35(6): 1327-1335.
[31] 杨树德, 李旺, 张新闻, 等. 一种提高变流器弱电网适应能力的虚拟阻抗控制策略[J/OL]. 电源学报, 2021: 1-14. (2021-10-14). https://kns.cnki.net/kcms/detail/12.1420.TM.20211014.1354.002.html.
Yang Shude, Li Wang, Zhang Xinwen, et al. A virtual-impedance based control strategy for improving the adaptability of converter to weak grid[J/OL]. Journal of Power Supply, 2021: 1-14. (2021-10-14). https://kns.cnki.net/kcms/detail/12.1420.TM.20211014.1354.002.html. |
|
|
|
2023, Vol. 38 
