|
|
|
| The Interaction Among Active Dampers in Multi-Inverter Grid-Connected System and Its Enhancement of Oscillation Suppression |
| Yang Ling1,2, Zhu Difan1, Ye Meiting1, Li Jiewen1, Luo Jianqiang1 |
1. School of Automation Guangdong University of Technology Guangzhou 510006 China;
2. State Key Laboratory of High-Efficiency and High-Quality Conversion for Electric Power Hunan University Changsha 410082 China |
|
|
|
Abstract In a multi-inverter grid-connected system, due to the inverters' nonlinear characteristics and the weak grid characteristics, the dynamic interaction between the inverters and the grid poses a serious threat to system stability. Additionally, the system often faces power quality issues, including power-sharing mismatch caused by line impedance differences among inverters and potential voltage drop. Existing control methods struggle to achieve compatibility among controllers, which hinders their ability to address the three problems simultaneously.
This paper proposes an active damping-based control strategy to enhance power quality in a multi-inverter grid-connected system. The interaction between the active damper controllers is analyzed. The proposed strategy consists of three active controllers: damper K, virtual impedance Zv(s), and an adaptive voltage compensator. Based on the established dq small-signal model of the multi-inverter grid-connected system, the impact of the proposed strategy on system damping is investigated. The strategy can amplify the system damping by a factor of [1+KGi(s)/(Rf+Gi(s))], thereby enhancing robustness and improving the stability margin. By plotting the real/imaginary parts of the total inverter output impedance, the effectiveness of the proposed strategy in achieving power sharing is studied. The results demonstrate that the total output impedance can be reshaped. When the introduced virtual inductance Lv counteracts the line inductance Lx, the power decoupling condition can be satisfied. By increasing the introduced virtual resistance Rv, accurate power sharing can be achieved.
The co-action effect of the introduced active damper controllers on oscillation suppression is analyzed. It shows a synergistic interaction effect between the damper K and the virtual impedance Zv(s): As the damper K increases, the dynamic interactions in the mid-to-low frequency range are better suppressed. Still, adverse effects are introduced in the high-frequency range. Instability at high frequencies should be avoided when increasing the value of K at low and medium frequencies. The virtual impedance Zv(s) can eliminate the detrimental high-frequency impact caused by damper K and preserve the suppression performance in the mid-low frequency band. Virtual inductance (Lv) is introduced to mitigate dynamic interaction and enhance stability in the high-frequency range, while virtual resistance (Rv) is adjusted to improve stability at low frequencies. The coordinated operation of damper K and virtual impedance Zv(s) eliminates the risk of dynamic interaction across the entire frequency range, improving system stability.
A hardware-in-the-loop experimental platform is established. The experimental results demonstrate that under the proposed control strategy, the system remains stable under weak grid conditions. The output power difference among inverters is as low as 0.22%, with a 98.5% improvement in power-sharing accuracy. Additionally, the PCC voltage deviation is reduced from 10% to 1.3%, and the inverter output active power is significantly enhanced from 18 330 W to 95 370 W, representing a 420% improvement. The proposed active damping control strategy demonstrates excellent compatibility in terms of system stability improvement, accurate power sharing, voltage recovery, and output power enhancement.
|
|
Received: 15 April 2025
|
|
|
|
|
|
[1] 高本锋, 刘培鑫, 孙大卫, 等. 构网/跟网型混合风电场次同步振荡特性与机理分析[J]. 电工技术学报, 2025, 40(6): 1945-1959.
Gao Benfeng, Liu Peixin, Sun Dawei, et al.Analysis of subsynchronous oscillation characteristics and mechanism of grid-forming/grid-following hybrid wind farms[J]. Transactions of China Electrotechnical Society, 2025, 40(6): 1945-1959.
[2] 彭程, 徐建勇, 赵书琪, 等. 考虑分层碳排放的多时间尺度光储充一体站日前运行策略[J]. 电气技术, 2025, 26(1): 1-13, 63.
Peng Cheng, Xu Jianyong, Zhao Shuqi, et al.Day- ahead operation strategy for a multi-timescale integrated photovoltaic storage and charging station considering carbon emission stratification[J]. Electrical Engineering, 2025, 26(1): 1-13, 63.
[3] 张斌, 张学广, 徐殿国. 构网型与跟网型变流器混联并网系统配比关键影响因素分析[J]. 电力系统自动化, 2025, 49(1): 47-58.
Zhang Bin, Zhang Xueguang, Xu Dianguo.Analysis on key influence factors of ratio of grid-forming and grid-following converters in hybrid parallel grid- connected system[J]. Automation of Electric Power Systems, 2025, 49(1): 47-58.
[4] Hu Bin, Zhan Ling, Nian Heng, et al.PLL frequency stability enhancement under weak grid considering reactive current support[J]. CES Transactions on Electrical Machines and Systems, 2025, 9(1): 110-114.
[5] 吴旭, 王伟, 肖华锋, 等. 并网逆变器整体序阻抗建模方法及其稳定性分析[J]. 中国电机工程学报, 2024, 44(9): 3645-3656.
Wu Xu, Wang Wei, Xiao Huafeng, et al.Overall sequence impedance model of grid-connected inverter and its stability analysis[J]. Proceedings of the CSEE, 2024, 44(9): 3645-3656.
[6] 王鹏飞, 陈家伟, 罗超, 等. 跟网型逆变器同步稳定性分析及增强控制方法[J]. 电工技术学报, 2026, 41(7): 2397-2410.
Wang Pengfei, Chen Jiawei, Luo Chao, et al.Syn- chronous stability analysis and enhancement control method for grid-following inverters[J]. Transactions of China Electrotechnical Society, 2026, 41(7): 2397-2410.
[7] 郑凯元, 杜文娟, 王海风. 混联多微电网系统动态交互作用及稳定性分析[J]. 中国电机工程学报, 2021, 41(16): 5552-5569.
Zheng Kaiyuan, Du Wenjuan, Wang Haifeng.Analysis on dynamic interactions and stability of hybrid multi-microgrids[J]. Proceedings of the CSEE, 2021, 41(16): 5552-5569.
[8] Li Ming, Zhang Xing, Guo Zixuan, et al.The control strategy for the grid-connected inverter through impe- dance reshaping in q-axis and its stability analysis under a weak grid[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2021, 9(3): 3229-3242.
[9] 陈杰, 刘名凹, 陈新, 等. 基于下垂控制的逆变器无线并联与环流抑制技术[J]. 电工技术学报, 2018, 33(7): 1450-1460.
Chen Jie, Liu Ming'ao, Chen Xin, et al.Wireless parallel and circulation current reduction of droop- controlled inverters[J]. Transactions of China Elec- trotechnical Society, 2018, 33(7): 1450-1460.
[10] Wang Xinsheng, Zhang Jiancheng, Zheng Mingli, et al.A distributed reactive power sharing approach in microgrids with improved droop control[J]. CSEE Journal of Power and Energy Systems, 2021, 7(6): 1238-1246.
[11] Wai R J, Zhang Quanquan, Wang Yu.A novel voltage stabilization and power sharing control method based on virtual complex impedance for an off-grid micro- grid[J]. IEEE Transactions on Power Electronics, 2019, 34(2): 1863-1880.
[12] 刘腾飞, 田艳军, 姜玉霞, 等. 基于有源阻尼电流观测器的并网逆变器无电流传感器反馈控制[J]. 中国电机工程学报, 2022, 42(19): 7182-7194.
Liu Tengfei, Tian Yanjun, Jiang Yuxia, et al.Active damped current observer oriented current sensorless feedback control for grid connected inverter[J]. Proceedings of the CSEE, 2022, 42(19): 7182-7194.
[13] 李明明, 肖华锋. 负带通滤波器反馈进网电流有源阻尼方法的实现技术研究[J]. 中国电机工程学报, 2022, 42(10): 3729-3738.
Li Mingming, Xiao Huafeng.Research on the technology of realizing active damping based on negative Band-pass filter feedback of grid current[J]. Proceedings of the CSEE, 2022, 42(10): 3729-3738.
[14] Li Shaojie, Lin Hua.A capacitor-current-feedback positive active damping control strategy for LCL-type grid-connected inverter to achieve high robustness[J]. IEEE Transactions on Power Electronics, 2022, 37(6): 6462-6474.
[15] Lin Zhiheng, Ruan Xinbo, Wu Liguo, et al.Multi resonant component-based grid-voltage-weighted feed- forward scheme for grid-connected inverter to suppress the injected grid current harmonics under weak grid[J]. IEEE Transactions on Power Elec- tronics, 2020, 35(9): 9784-9793.
[16] 杨树德, 李旺, 徐佳, 等. 基于并网电流谐波微分的有源阻尼策略[J]. 电工技术学报, 2023, 38(23): 6305-6317.
Yang Shude, Li Wang, Xu Jia, et al.Research on active damping strategy based on the differentiation of injected grid current harmonics[J]. Transactions of China Electrotechnical Society, 2023, 38(23): 6305-6317.
[17] Cai Yuxi, He Yingjie, Zhou Hongwei, et al.Active- damping disturbance-rejection control strategy of LCL grid-connected inverter based on inverter-side- current feedback[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2021, 9(6): 7183-7198.
[18] 曹子恒, 肖先勇, 马俊鹏, 等. 提高LCL型并网逆变器鲁棒性的改进型电容电流反馈有源阻尼策略[J]. 高电压技术, 2020, 46(11): 3781-3790.
Cao Ziheng, Xiao Xianyong, Ma Junpeng, et al.Novel capacitor current feedback active damping strategy for enhancing robustness of LCL-type grid-connected inverters[J]. High Voltage Engineering, 2020, 46(11): 3781-3790.
[19] 郑堃, 周林, 龙贵欣, 等. 一种针对数字控制下光伏并网逆变器的陷波器滞后补偿方法[J]. 中国电机工程学报, 2019, 39(6): 1749-1757, 1871.
Zheng Kun, Zhou Lin, Long Guixin, et al.A lag compensation method based on Notch filter for PV grid-connected inverter under digital control[J]. Proceedings of the CSEE, 2019, 39(6): 1749-1757, 1871.
[20] 高磊, 吕敬, 马骏超, 等. 基于电路等效的并网逆变器失稳分析与稳定控制[J]. 电工技术学报, 2024, 39(8): 2325-2341.
Gao Lei, Lü Jing, Ma Junchao, et al.Instability analysis and stability control of grid-connected inverter based on impedance circuit equivalent[J]. Transactions of China Electrotechnical Society, 2024, 39(8): 2325-2341.
[21] Cao Wenyuan, Han Minxiao, Zhang Xiahui, et al.An integrated synchronization and control strategy for parallel-operated inverters based on V-I droop characteristics[J]. IEEE Transactions on Power Electronics, 2022, 37(5): 5373-5384.
[22] Ramezani M, Li Shuhui, Sun Yang.Combining droop and direct current vector control for control of parallel inverters in microgrid[J]. IET Renewable Power Generation, 2017, 11(1): 107-114.
[23] 王鹏程, 陈敏, 朱冠南, 等. 基于电压补偿的下垂控制变换器功率解耦策略[J]. 电工技术学报, 2026, 41(3): 821-833.
Wang Pengcheng, Chen Min, Zhu Guannan, et al.Voltage compensation-based power decoupling strategy for droop control converters[J]. Transactions of China Electrotechnical Society, 2026, 41(3): 821-833.
[24] 姜恩宇, 施峥靖, 赵吉康, 等. 基于时序分阶段控制的网状微电网功率均分策略[J]. 太阳能学报, 2022, 43(8): 490-497.
Jiang Enyu, Shi Zhengjing, Zhao Jikang, et al.Power sharing strategy for meshed microgrid based on time sequence and stage control[J]. Acta Energiae Solaris Sinica, 2022, 43(8): 490-497.
[25] Moussa H, Shahin A, Martin J P, et al.Optimal angle droop for power sharing enhancement with stability improvement in islanded microgrids[J]. IEEE Transa- ctions on Smart Grid, 2018, 9(5): 5014-5026.
[26] 范必双, 付思维, 王文, 等. 基于自适应虚拟电阻的低压微电网有功均分下垂控制策略[J]. 电机与控制学报, 2024, 28(5): 142-153.
Fan Bishuang, Fu Siwei, Wang Wen, et al.Active power sharing droop control strategy for low-voltage microgrid based on adaptive virtual resistance[J]. Electric Machines and Control, 2024, 28(5): 142-153.
[27] Chen Yandong, Guerrero J M, Shuai Zhikang, et al.Fast reactive power sharing, circulating current and resonance suppression for parallel inverters using resistive-capacitive output impedance[J]. IEEE Transa- ctions on Power Electronics, 2016, 31(8): 5524-5537.
[28] Guan Yajuan, Guerrero J M, Zhao Xin, et al.A new way of controlling parallel-connected inverters by using synchronous-reference-frame virtual impedance loop: part I: control principle[J]. IEEE Transactions on Power Electronics, 2016, 31(6): 4576-4593.
[29] 彭志豪, 黄海益, 杨苓. 一种具有自适应电压补偿和恢复功能的微电网功率均分策略[J]. 太阳能学报, 2023, 44(7): 61-70.
Peng Zhihao, Huang Haiyi, Yang Ling.A microgrid power sharing strategy with adaptive voltage com- pensation and restoration[J]. Acta Energiae Solaris Sinica, 2023, 44(7): 61-70.
[30] Liu Bin, Li Zhen, Dong Xiaoliang, et al.Impedance modeling and controllers shaping effect analysis of PMSG wind turbines[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2020, 9(2): 1465-1478.
[31] Radwan A A A, Mohamed Y A I. Stabilization of medium-frequency modes in isolated microgrids supplying direct online induction motor loads[J]. IEEE Transactions on Smart Grid, 2014, 5(1): 358-370. |
|
|
|
2026, Vol. 41 
