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| Small-Signal Low-Frequency Stability Analysis of Power Systems with Grid-Following and Grid-Forming Devices Based on System Strength |
| Zhan Xiuyu1, Yuan Hui2, Hu Guang3, Xin Huanhai1,3,4 |
1. Polytechnic Institute Zhejiang University Hangzhou 310027 China;
2. College of Electrical Engineering Guangxi University Nanning 530004 China;
3. College of Electrical Engineering Zhejiang University Hangzhou 310027 China;
4. Zhejiang Key Laboratory of Electrical Technology and System on Renewable Energy Hangzhou 310027 China |
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Abstract The future power system will present a new hybrid grid-connected configuration with both grid-following devices (GFLDs) and grid-forming devices (GFMDs). Due to the strong stochasticity of renewable power generations, the system may encounter high short-circuit ratio (SCR) scenarios with low penetration of renewable power generations under extreme conditions. This may cause GFMD-induced low-frequency oscillation issues where the oscillation frequency is in the range of [0.1 Hz, 2.5 Hz]. Therefore, it is important to investigate how the interaction among GFMDs influence the low-frequency oscillation stability, and how the connection of GFLDs influence this type of oscillation stability. The existing research commonly investigated the sub-synchronous oscillation issues dominated by GFLDs in weak grids. Only a few works discussed the GFMD-induced low-frequency oscillation issues with the assumption that the GFMDs are homogeneous. However, it is still unknown how the interaction among heterogeneous GFLDs and GFMDs influences this type of low-frequency oscillation issues. Due to this, this paper proposes a novel method to evaluate small-signal low-frequency stability of power systems with GFLDs and GFMDs from the perspective of system strength.
Firstly, to simplify the analysis, this paper constructs simplified dynamic models of GFLDs and GFMDs suitable for low-frequency oscillation analysis. Secondly, based on matrix perturbation theory, equivalent homogeneous systems that approximately reflect the low-frequency dominant mode of the original system are constructed for the multi-GFMDs system considering heterogeneous GFMDs and the connection of GFLDs, where the established homogeneous system retains the network structure characteristics of the original system. Furtherly, the eigen-subsystem are derived, which can reflect the low-frequency dominant mode of the original system. On this basis, from the perspective of system strength, the low-frequency oscillation stability evaluation index of the original complex multi-infeed system is proposed, and the mechanism of the heterogeneous characteristics of grid-forming devices and the interaction between grid-following and grid-forming devices on the low-frequency oscillation of the system is revealed. Finally, the proposed analysis method is validated through case studies on a three-infeed system with two GFMDs and a GFLD and a modified IEEE 39-node system.
The following conclusions can be drawn: (1) The proposed simplified models of GFLD and GFMD are applicable to the low-frequency oscillation stability analysis of hybrid multi-infeed systems, which is verified based on detailed electromagnetic transient models; the constructed eigen-subsystem can approximately reflect the low-frequency stability of the original complex multi-infeed system. (2) The proposed generalized short-circuit ratio (gSCR) index and its critical value effectively reflect system strength and low-frequency stability margin in hybrid renewable energy systems, which simplifies the complexity of the stability analysis. (3) From the perspective of system strength, the connection of GFLDs has no impact on grid strength, but influence the critical value of grid strength. Therefore, the impact of the connection of GFLDs on the low-frequency oscillation stability of the system can be equivalently regarded as changing the maximal SCR requirement of the original multi-grid-forming device grid-connected system, thereby affecting the low-frequency stability of the system. Besides, how the GFLDs influence the maximal gSCR requirement depends on the control structure and control parameters of the GFLDs (the addition of GFLDs may improve or deteriorate the system stability).
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Received: 07 January 2025
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[1] 黄萌, 舒思睿, 李锡林, 等. 面向同步稳定性的电力电子并网变流器分析与控制研究综述[J]. 电工技术学报, 2024, 39(19): 5978-5994.
Huang Meng, Shu Sirui, Li Xilin, et al.A review of synchronization-stability-oriented analysis and control of power electronic grid-connected converters[J]. Transactions of China Electrotechnical Society, 2024, 39(19): 5978-5994.
[2] 李红, 梁军杨, 王振民, 等. 跟网型变换器的小扰动同步稳定机理分析与致稳控制[J]. 电工技术学报, 2024, 39(12): 3802-3815.
Li Hong, Liang Junyang, Wang Zhenmin, et al.Small signal synchronization stability analysis and improved control strategy for grid following converter[J]. Transactions of China Electrotechnical Society, 2024, 39(12): 3802-3815.
[3] Ndreko M, Rüberg S, Winter W.Grid forming control scheme for power systems with up to 100% power electronic interfaced generation: a case study on Great Britain test system[J]. IET Renewable Power Generation, 2020, 14(8): 1268-1281.
[4] 朱廷猛, 孙海顺, 秦世耀, 等. 弱电网下双馈风机并网系统的次同步振荡研究[J]. 电网技术, 2021, 45(5): 1641-1648.
Zhu Tingmeng, Sun Haishun, Qin Shiyao, et al.Sub-synchronous oscillation in DFIG system connected to weak grid[J]. Power System Technology, 2021, 45(5): 1641-1648.
[5] 詹长江, 吴恒, 王雄飞, 等. 构网型变流器稳定性研究综述[J]. 中国电机工程学报, 2023, 43(6): 2339-2359.
Zhan Changjiang, Wu Heng, Wang Xiongfei, et al.An overview of stability studies of grid-forming voltage source converters[J]. Proceedings of the CSEE, 2023, 43(6): 2339-2359.
[6] Rosso R, Engelken S, Liserre M.Robust stability investigation of the interactions among grid-forming and grid-following converters[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2020, 8(2): 991-1003.
[7] Guo Jian, Chen Yandong, Wang Lei, et al.Impedance analysis and stabilization of virtual synchronous generators with different DC-link voltage controllers under weak grid[J]. IEEE Transactions on Power Electronics, 2021, 36(10): 11397-11408.
[8] 韩应生, 孙海顺, 秦世耀, 等. 电压源型双馈风电并网系统小扰动低频稳定性分析[J]. 电工技术学报, 2023, 38(5): 1312-1324, 1374.
Han Yingsheng, Sun Haishun, Qin Shiyao, et al.Low-frequency stability analysis of voltage-sourced doubly-fed wind power grid-connected system under small disturbance[J]. Transactions of China Electrotechnical Society, 2023, 38(5): 1312-1324, 1374.
[9] Tan J, Dong S, Hoke A.Lessons learned from real-world oscillation events[C]//IEEE PES General Meeting, Orlando, FL, USA, 2023: 16-20.
[10] 辛焕海, 李子恒, 董炜, 等. 三相变流器并网系统的广义阻抗及稳定判据[J]. 中国电机工程学报, 2017, 37(5): 1277-1293.
Xin Huanhai, Li Ziheng, Dong Wei, et al.Generalized-impedance and stability criterion for grid-connected converters[J]. Proceedings of the CSEE, 2017, 37(5): 1277-1293.
[11] Liao Yicheng, Wang Xiongfei.Impedance-based stability analysis for interconnected converter systems with open-loop RHP poles[J]. IEEE Transactions on Power Electronics, 2020, 35(4): 4388-4397.
[12] Li Yang, Shuai Zhikang, Liu Xuan, et al.Stability analysis and location optimization method for multiconverter power systems based on nodal admittance matrix[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2021, 9(1): 529-538.
[13] 周瑀涵, 辛焕海, 鞠平. 基于广义短路比的多馈入系统强度量化原理与方法: 回顾、探讨与展望[J]. 中国电机工程学报, 2023, 43(10): 3794-3811.
Zhou Yuhan, Xin Huanhai, Ju Ping.System strength quantification principle and method of multi-infeed systems based on generalized short-circuit ratio: reviews, discussions and outlooks[J]. Proceedings of the CSEE, 2023, 43(10): 3794-3811.
[14] 王子骏, 庄可好, 辛焕海, 等. 虚拟同步直驱风机低频振荡机理分析及阻尼补偿控制[J]. 电力系统自动化, 2024, 48(2): 95-104.
Wang Zijun, Zhuang Kehao, Xin Huanhai, et al.Low-frequency oscillation mechanism analysis and damping compensation control of virtual synchronous direct-driven wind turbine generators[J]. Automation of Electric Power Systems, 2024, 48(2): 95-104.
[15] 王玉坤, 张慕婕, 李壮, 等. 构网型直驱风电机组间控制相互作用研究[J]. 电力自动化设备, 2024, 44(3): 82-90.
Wang Yukun, Zhang Mujie, Li Zhuang, et al.Research on control interaction between grid forming direct-drive wind turbines[J]. Electric Power Automation Equipment, 2024, 44(3): 82-90.
[16] 余光正, 胡越, 刘晨曦, 等. 含跟网/构网型混联多馈入系统协调优化配置方法[J]. 中国电机工程学报, 2025, 45(2): 588-601.
Yu Guangzheng, Hu Yue, Liu Chenxi, et al.Research on the coordinated optimization configuration method for hybrid multi-infeed systems with grid-following or grid-forming[J]. Proceedings of the CSEE, 2025, 45(2): 588-601.
[17] 方正, 黄云辉, 严文博, 等. 构网型与跟网型变流器交互作用对并联系统小干扰稳定性的影响分析[J]. 电力自动化设备, 2025, 45(2): 134-142.
Fang Zheng, Huang Yunhui, Yan Wenbo, et al.Influence analysis of interaction between grid-forming and grid-following converters on small interference stability of parallel system[J]. Electric Power Automation Equipment, 2025, 45(2): 134-142.
[18] 郭小龙, 杨桂兴, 张彦军, 等. 构网型储能与跟网型光伏混联发电系统阻抗建模与小扰动稳定机理分析[J]. 电气工程学报, 2025, 20(1): 299-308.
Guo Xiaolong, Yang Guixing, Zhang Yanjun, et al.Impedance modeling and small-signal stability mechanism analysis of grid-forming energy storage and grid-following PV hybrid power generation system[J]. Journal of Electrical Engineering, 2025, 20(1): 299-308.
[19] 盛李龙, 许津铭, 李威, 等. 弱电网下跟/构网型变流器并联系统的阻抗频率耦合及稳定性分析[J]. 电力系统自动化, 2025, 49(1): 27-37.
Sheng Lilong, Xu Jinming, Li Wei, et al.Impedance frequency coupling and stability analysis of parallel system of grid-following and gridforming converters in weak grid[J]. Automation of Electric Power Systems, 2025, 49(1): 27-37.
[20] Yang Chaoran, Huang Linbin, Xin Huanhai, et al.Placing grid-forming converters to enhance small signal stability of PLL-integrated power systems[J]. IEEE Transactions on Power Systems, 2021, 36(4): 3563-3573.
[21] 辛焕海, 甘德强, 鞠平. 多馈入电力系统广义短路比: 多样化新能源场景[J]. 中国电机工程学报, 2020, 40(17): 5516-5527.
Xin Huanhai, Gan Deqiang, Ju Ping.Generalized short circuit ratio of power systems with multiple power electronic devices: analysis for various renewable power generations[J]. Proceedings of the CSEE, 2020, 40(17): 5516-5527.
[22] 袁辉, 辛焕海, 王冠中, 等. 含SVG的新能源多馈入系统振荡分析和广义短路比计算[J]. 电力系统自动化, 2021, 45(14): 38-46.
Yuan Hui, Xin Huanhai, Wang Guanzhong, et al.Analysis on oscillation of multi-infeed system with renewable energy and static var generator and calculation of its generalized short-circuit ratio[J]. Automation of Electric Power Systems, 2021, 45(14): 38-46.
[23] Gönen T.Modern Power System Analysis[M]. 2nd ed. Oxfordshire: Taylor and Francis, 2013.
[24] 辛焕海, 刘晨曦, 黄林彬, 等. 基于特征子系统的广义短路比导出原理及计算方法[J]. 中国电机工程学报, 2025, 45(7): 2447-2461.
Xin Huanhai, Liu Chenxi, Huang Linbin, et al.Derivation principle and calculation method of generalized short-circuit ratio based on eigen-subsystems[J]. Proceedings of the CSEE, 2025, 45(7): 2447-2461.
[25] Stewart G W.Matrix Perturbation Theory[M]. Salt Lake City: Academic Press, 1990. |
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2026, Vol. 41 
