Abstract：As an important interface between new energy power generation and the grid, the Voltage Source Converter (VSC) has been widely used in new power systems. At present, the grid following VSC based on current vector control has extensive application in engineering practice. However, with the increasing integration of new energy sources and the continuous addition of power electronic equipment, power grid stability weakens, leading to challenges in the stability of grid-following VSCs. The concept of grid-forming VSC is proposed to improve the stability, especially in weak grid scenarios and for power supply to isolated islands. Power Synchronization Control (PSC) and Virtual Synchronous Generator (VSG) control have gained significant attention due to their simplicity. It is found that PSC control with a first-order low-pass filter can be equivalent to VSG control when the influence of energy storage is ignored. However, an issue known as Synchronous Frequency Resonance (SFR) arises when VSCs controlled by PSC or VSG are connected to inductive grids with small equivalent resistances. Based on the control equation, VSG control and PSC control with a first-order low-pass filter can be equivalent to each other. The coupling effect between the active power control loop (APCL) and reactive power control loop (RPCL) is explored, and an equivalent mathematical model for their mutual coupling is deduced. Secondly, the influence of the voltage and current inner loop dynamics of the system is analyzed, demonstrating that the inner loop does not change the system characteristics near the synchronization frequency. Therefore, to simplify the analysis of the synchronous frequency resonance mechanism, the inner loop is considered fast enough to achieve ideal voltage tracking. Thirdly, based on the small signal model in the frequency domain, it is verified that a small equivalent resistance in an inductive grid may cause SFR, and power control loop parameters can affect system stability. The Nyquist criterion analysis indicates that the presence of a non-minimum phase system is a cause of SFR. Finally, the mechanism of the SFR phenomenon of the grid-forming converter is analyzed, and an SFR suppression strategy is proposed. The effectiveness of the proposed method is verified. The following conclusions can be drawn from the analysis: (1) A small signal model in the frequency domain of grid-forming PSC-VSC coupled with APCL and RPCL is established. According to the closed-loop system eigenvalue loci, it is verified that a small equivalent resistance of the inductive grid can cause SFR. The non-minimum phase effect is another reason for SFR. (2) Compared with the first-order low-pass filter (equivalent to VSG control), the proposed SFR suppression method can effectively suppress the resonance peak and require lower precision of parameter design. Meanwhile, it also has strong robustness in control parameters and a more substantial stability margin for the system. (3) The theoretical analysis is verified based on the established three-phase grid-connected converter experiment platform.
熊小玲, 李昕悦, 周琰, 罗博晨. 基于陷波器的构网型换流器同步频率谐制策略[J]. 电工技术学报, 2024, 39(12): 3827-3839.
Xiong Xiaoling, Li Xinyue, Zhou Yan, Luo Bochen. Synchronous Frequency Resonance Suppression of Grid-Forming Converter Based on Notch Filter. Transactions of China Electrotechnical Society, 2024, 39(12): 3827-3839.
[1] 马宁宁, 谢小荣, 贺静波, 等. 高比例新能源和电力电子设备电力系统的宽频振荡研究综述[J]. 中国电机工程学报, 2020, 40(15): 4720-4732. Ma Ningning, Xie Xiaorong, He Jingbo, et al.Review of wide-band oscillation in renewable and power electronics highly integrated power systems[J]. Pro- ceedings of the CSEE, 2020, 40(15): 4720-4732. [2] 张尧翔, 刘文颖, 庞清仑, 等. 高比例风电接入系统光热发电-火电旋转备用优化方法[J]. 电工技术学报, 2022, 37(21): 5478-5489. Zhang Yaoxiang, Liu Wenying, Pang Qinglun, et al.Optimal power spinning reserve method of con- centrating solar power and thermal power for high- proportion wind power system[J]. Transactions of China Electrotechnical Society, 2022, 37(21): 5478-5489. [3] 杨铭, 曹武, 赵剑锋, 等. 受控电压/电流源型变流器混合多机暂态电压支撑策略[J]. 电工技术学报, 2023, 38(19): 5207-5223, 5240. Yang Ming, Cao Wu, Zhao Jianfeng, et al.Transient voltage support strategy for hybrid multi-converter of controlled voltage/current source converter[J]. Transa- ctions of China Electrotechnical Society, 2023, 38(19): 5207-5223, 5240. [4] 杜步阳, 邵德军, 朱建行, 等. 电压源型变流器并网系统多时间尺度间相互作用[J]. 电工技术学报, 2023, 38(20): 5547-5559. Du Buyang, Shao Dejun, Zhu Jianhang, et al.The interaction between multiple timescales of the grid-tied voltage source converter[J]. Transactions of China Electrotechnical Society, 2023, 38(20): 5547-5559. [5] 胡宇飞, 田震, 查晓明, 等. 构网型与跟网型变流器主导孤岛微网阻抗稳定性分析及提升策略[J]. 电力系统自动化, 2022, 46(24): 121-131. Hu Yufei, Tian Zhen, Zha Xiaoming, et al.Impedance stability analysis and promotion strategy of islanded microgrid dominated by grid-connected and grid- following converters[J]. Automation of Electric Power Systems, 2022, 46(24): 121-131. [6] 温春雪, 黄耀智, 胡长斌, 等. 虚拟同步发电机接口变换器并联运行虚拟阻抗自适应控制[J]. 电工技术学报, 2020, 35(增刊2): 494-502. Wen Chunxue, Huang Yaozhi, Hu Changbin, et al.Adaptive control of virtual impedance in parallel operation of virtual synchronous generator interface converter[J]. Transactions of China Electrotechnical Society, 2020, 35(S2): 494-502. [7] 颜湘武, 张伟超, 崔森, 等. 基于虚拟同步机的电压源逆变器频率响应时域特性和自适应参数设计[J]. 电工技术学报, 2021, 36(增刊1): 241-254. Yan Xiangwu, Zhang Weichao, Cui Sen, et al.Frequency response characteristics and adaptive parameter tuning of voltage-sourced converters under VSG control[J]. Transactions of China Electro- technical Society, 2021, 36(S1): 241-254. [8] 涂春鸣, 邹凯星, 高家元, 等. 基于不对称正负反馈效应的PQ功率控制并网逆变器稳定性分析[J]. 电工技术学报, 2023, 38(2): 496-509. Tu Chunming, Zou Kaixing, Gao Jiayuan, et al.Stability analysis of grid-connected inverter under PQ power control based on asymmetric positive-negative- feedback effects[J]. Transactions of China Electro- technical Society, 2023, 38(2): 496-509. [9] 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. [10] 于彦雪, 马慧敏, 陈晓光, 等. 弱电网下基于准静态模型的混合控制微电网逆变器同步稳定性研究[J]. 电工技术学报, 2022, 37(1): 152-164. Yu Yanxue, Ma Huimin, Chen Xiaoguang, et al.Synchronous stability research of inverters in hybrid microgrid based on the quasi-static models under weak grid[J]. Transactions of China Electrotechnical Society, 2022, 37(1): 152-164. [11] Wen Bo, Dong Dong, Boroyevich D, et al.Impedance-based analysis of grid-synchronization stability for three-phase paralleled converters[J]. IEEE Transactions on Power Electronics, 2016, 31(1): 26-38. [12] Wu Heng, Ruan Xinbo, Yang Dongsheng, et al.Small-signal modeling and parameters design for virtual synchronous generators[J]. IEEE Transactions on Industrial Electronics, 2016, 63(7): 4292-4303. [13] 刘津铭, 陈燕东, 伍文华, 等. 孤岛微电网序阻抗建模与高频振荡抑制[J]. 电工技术学报, 2020, 35(7): 1538-1552. Liu Jinming, Chen Yandong, Wu Wenhua, et al.Sequence impedance modeling and high-frequency oscillation suppression method for island microgrid[J]. Transactions of China Electrotechnical Society, 2020, 35(7): 1538-1552. [14] 王志洁, 李书江, 胡红阳, 等. 构网型光伏发电系统振荡模态分析及抑制策略[J]. 电力电子技术, 2022, 56(12): 82-86. Wang Zhijie, Li Shujiang, Hu Hongyang, et al.Oscillation mode analysis and suppression strategy of grid-forming photovoltaic power generation system[J]. Power Electronics, 2022, 56(12): 82-86. [15] 李梦杰, 谢震, 高翔, 等. 弱电网下双馈风电机组混合功率同步控制策略及稳定性分析[J]. 中国电机工程学报, 2023, 43(21): 8388-8400. Li Mengjie, Xie Zhen, Gao Xiang, et al.Hybrid power synchronization control strategy of DFIG-based wind turbines and its stability analysis under weak grid[J]. Proceedings of the CSEE, 2023, 43(21): 8388-8400. [16] Zhang Lidong, Harnefors L, Nee H P.Power- synchronization control of grid-connected voltage- source converters[J]. IEEE Transactions on Power Systems, 2010, 25(2): 809-820. [17] 潘子迅, 杨晓峰, 赵锐, 等. 不平衡电网下虚拟同步机的多模式协调策略[J]. 电工技术学报, 2023, 38(16): 4274-4285. Pan Zixun, Yang Xiaofeng, Zhao Rui, et al.Multi- mode coordination control of virtual synchronous generator under unbalanced power grid[J]. Transa- ctions of China Electrotechnical Society, 2023, 38(16): 4274-4285. [18] 徐健, 曹鑫, 郝振洋, 等. 基于电网谐波电压前馈的虚拟同步整流器电流谐波抑制方法[J]. 电工技术学报, 2022, 37(8): 2018-2029. Xu Jian, Cao Xin, Hao Zhenyang, et al.A harmonic- current suppression method for virtual synchronous rectifier based on feedforward of grid harmonic voltage[J]. Transactions of China Electrotechnical Society, 2022, 37(8): 2018-2029. [19] Xiong Xiaoling, Wu Chao, Blaabjerg F.An improved synchronization stability method of virtual syn- chronous generators based on frequency feedforward on reactive power control loop[J]. IEEE Transactions on Power Electronics, 2021, 36(8): 9136-9148. [20] 于彦雪, 关万琳, 陈晓光, 等. 基于序阻抗的虚拟同步机同步频率谐振现象[J]. 电工技术学报, 2022, 37(10): 2584-2595. Yu Yanxue, Guan Wanlin, Chen Xiaoguang, et al.Synchronous frequency resonance in virtual syn- chronous generator based on sequence-impedance[J]. Transactions of China Electrotechnical Society, 2022, 37(10): 2584-2595. [21] 吴恒, 阮新波, 杨东升, 等. 虚拟同步发电机功率环的建模与参数设计[J]. 中国电机工程学报, 2015, 35(24): 6508-6518. Wu Heng, Ruan Xinbo, Yang Dongsheng, et al.Modeling of the power loop and parameter design of virtual synchronous generators[J]. Proceedings of the CSEE, 2015, 35(24): 6508-6518. [22] Yang Dongsheng, Wu Heng, Wang Xiongfei, et al.Suppression of synchronous resonance for VSGs[J]. The Journal of Engineering, 2017, 2017(13): 2574-2579. [23] 李武华, 王金华, 杨贺雅, 等. 虚拟同步发电机的功率动态耦合机理及同步频率谐振抑制策略[J]. 中国电机工程学报, 2017, 37(2): 381-391. Li Wuhua, Wang Jinhua, Yang Heya, et al.Power dynamic coupling mechanism and resonance supper- ssion of synchronous frequency for virtual syn- chronous generators[J]. Proceedings of the CSEE, 2017, 37(2): 381-391. [24] 马也, 史丽萍, 李衡, 等. 基于VSG控制的微网逆变器工频振荡现象研究[J]. 电力系统保护与控制, 2022, 50(1): 107-115. Ma Ye, Shi Liping, Li Heng, et al.Power frequency oscillation of a microgrid inverter based on VSG control[J]. Power System Protection and Control, 2022, 50(1): 107-115. [25] Xiong Xiaoling, Wu Chao, Blaabjerg F.Effects of virtual resistance on transient stability of virtual synchronous generators under grid voltage sag[J]. IEEE Transactions on Industrial Electronics, 2022, 69(5): 4754-4764. [26] European Committee for Electrotechnical Standardi- zation. EN 50438 Requirements for the connection of micro generators in parallel with public low-voltage distribution networks[S]. 2008.
2024, Vol. 39 
