The Interaction Between Multiple Timescales of the Grid-Tied Voltage Source Converter
Du Buyang1, Shao Dejun2, Zhu Jianhang1, Shi Mengxuan2, Xu Youping2
1. State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China; 2. Central China Branch of State Grid Corporation of China Wuhan 430077 China
Abstract The voltage source converter's (VSC) control system and its interactions with the network are important factors that cause the instability of the grid-tied VSC. The control of VSC has a multiple timescale feature, which can be divided into DC-link voltage control (DVC) timescale and alternating current control (ACC) timescale. Existing research focuses on stability in a single timescale and rarely deals with the interaction between multiple timescales. Therefore, this paper uses the modal analysis to investigate the quantitative indicators and influencing factors of the interaction between different timescales of the grid-tied VSC. At the same time, the applicable scope of the models in DVC and ACC timescales is clarified, and the analysis results are preliminarily explained from a physical point of view. First, this paper briefly introduces the topology and control scheme of the grid-tied VSC and illustrates its multiple timescale dynamic characteristics. Next, the small-signal models of the grid-tied VSC in multiple timescales, DVC timescales, and ACC timescales are constructed. The accuracy of the above models is verified by the electromagnetic transient simulation and eigenvalue analysis. The participation factors for state variables and modes in different timescales are used based on the modal analysis method to measure the relative strength of the interaction between different timescales. The interaction variation between different timescales with the bandwidth of the phase-locked loop (PLL) and the short circuit ratio (SCR) is analyzed. By comparing the eigenvalue damping ratios and oscillation frequencies of the grid-tied VSC models in multiple timescales, DVC timescale, and ACC timescale, this paper shows that the interaction between multiple timescales has an impact on the system stability analysis results. Then, the deviations of eigenvalue damping ratios and oscillation frequencies of the DVC or ACC timescale models are analyzed when the PLL bandwidth and SCR vary. The applicable scope of the above models in a single timescale is clarified. Moreover, the theoretical analysis results are verified by electromagnetic transient simulation. Finally, the effects of the interaction between multiple timescales are initially explained from the physical level. The main conclusions of this paper are as follows. (1) The participation factors for state variables and modes in different timescales are defined as the different-scale participation factors, and different-scale participation factors can be used as a quantitative index to measure the interaction between multiple timescales. (2) When the PLL bandwidth increases or SCR decreases, the different-scale participation factors increase, which enhances the interaction between multiple timescales. (3) The influence of the interaction between multiple timescales on the analysis results of system stability is studied, and the applicable scope of the models in DVC and ACC timescales is proposed. The increase of PLL bandwidth or the decrease of SCR will enhance the interaction between multiple timescales, thus increasing the deviation of the eigenvalue analysis results of the models in a single timescale. (4) From the perspective of the parts in the DVC timescale, the inner control loops are equivalent to the damping links. Therefore, the eigenvalue analysis results of the model in the DVC timescale are lower in damping ratio and higher in oscillation frequency than those in the multiple timescale model. From the perspective of the parts in the ACC timescale, the outer control loops are equivalent to the excitation, so the eigenvalue oscillation frequency obtained by the model in the ACC timescale is much lower.
Du Buyang,Shao Dejun,Zhu Jianhang等. The Interaction Between Multiple Timescales of the Grid-Tied Voltage Source Converter[J]. Transactions of China Electrotechnical Society, 2023, 38(20): 5547-5559.
[1] Xie Xiaorong, Zhang Xu, Liu Huakun, et al.Charac- teristic analysis of subsynchronous resonance in practical wind farms connected to series-compensated transmissions[J]. IEEE Transactions on Energy Con- version, 2017, 32(3): 1117-1126. [2] 肖湘宁, 罗超, 廖坤玉. 新能源电力系统次同步振荡问题研究综述[J]. 电工技术学报, 2017, 32(6): 85-97. Xiao Xiangning, Luo Chao, Liao Kunyu.Review of the research on subsynchronous oscillation issues in electric power system with renewable energy sources[J]. Transactions of China Electrotechnical Society, 2017, 32(6): 85-97. [3] Liu Huakun, Xie Xiaorong, He Jingbo, et al.Sub- synchronous interaction between direct-drive PMSG based wind farms and weak AC networks[J]. IEEE Transactions on Power Systems, 2017, 32(6): 4708-4720. [4] 张东辉, 陈新, 杨舒婷, 等. 含静止无功补偿装置的光伏电站高频谐振分析及抑制策略研究[J/OL]. 中国电机工程学报. https://kns.cnki.net/kcms/detail/ 11.2107.TM.20220707.1548.014.html. Zhang Donghui, Chen Xin, Yang Shuting, et al. Analysis of high-frequency resonance and suppression strategy of photovoltaic power plant with static reactive power compensation device[J/OL]. Pro- ceedings of the CSEE. https://kns.cnki.net/kcms/detail/ 11.2107.TM.20220707.1548.014.html. [5] 颜湘武, 常文斐, 崔森, 等. 基于线性自抗扰控制的静止无功补偿器抑制弱交流风电系统次同步振荡策略[J]. 电工技术学报, 2022, 37(11): 2825-2836. Yan Xiangwu, Chang Wenfei, Cui Sen, et al.Sub- synchronous oscillation suppression strategy of weak AC wind power system with static var compensator based on linear active disturbance rejection control[J]. Transactions of China Electrotechnical Society, 2022, 37(11): 2825-2836. [6] 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. 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 Electro- technical Society, 2023, 38(5): 1312-1324. [7] 徐海亮, 吴瀚, 李志, 等. 低短路比电网下含负序控制双馈风机稳定性研究的几个关键问题[J]. 电工技术学报, 2021, 36(22): 4688-4702. Xu Hailiang, Wu Han, Li Zhi, et al.Several key issues on stability study of DFIG-based wind turbines with negative sequence control during low short-circuit ratio power grids[J]. Transactions of China Electro- technical Society, 2021, 36(22): 4688-4702. [8] 袁小明, 程时杰, 胡家兵. 电力电子化电力系统多尺度电压功角动态稳定问题[J]. 中国电机工程学报, 2016, 36(19): 5145-5154, 5395. Yuan Xiaoming, Cheng Shijie, Hu Jiabing.Multi- timescale voltage and power angle dynamics in power electronics dominated large power systems[J]. Pro- ceedings of the CSEE, 2016, 36(19): 5145-5154, 5395. [9] Yuan Hao, Yuan Xiaoming, Hu Jiabing.Modeling of grid-connected VSCs for power system small-signal stability analysis in DC-link voltage control times- cale[J]. IEEE Transactions on Power Systems, 2017, 32(5): 3981-3991. [10] 黄云辉, 宋泽凡, 唐金锐, 等. 连接弱电网的并网变换器直流电压时间尺度稳定器的设计与分析[J].电工技术学报, 2018, 33(增刊1): 185-192. Huang Yunhui, Song Zefan, Tang Jinrui, et al.Design and analysis of DC-link voltage stabilizer for voltage source converter as connected to weak grid[J]. Transactions of China Electrotechnical Society, 2018, 33(S1): 185-192. [11] Zheng Wanning, Hu Jiabing, Yuan Xiaoming.Analytic quantification of interactions in MTDC systems based on self-/en-stabilizing coefficients in DC voltage control timescale[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2021, 9(3): 2980-2991. [12] 王一珺, 王海风. 直流电压动态时间尺度下大规模直驱风电场振荡稳定性及参数稳定域分析[J]. 中国电机工程学报, 2021, 41(增刊1): 92-107. Wang Yijun, Wang Haifeng.Analysis of oscillation stability and stability region of parameters in large- scale direct-drive wind farms under DC voltage dynamic time scale[J]. Proceedings of the CSEE, 2021, 41(S1): 92-107. [13] 严亚兵, 苗淼, 李胜, 等. 静止坐标系下变换器电流平衡-内电势运动模型: 一种装备电流控制尺度物理化建模方法[J]. 中国电机工程学报, 2017, 37(14): 3963-3972, 4274. Yan Yabing, Miao Miao, Li Sheng, et al.Current- balancing driven internal voltage motion model of voltage source converter in stationary frame: a physical modeling method in current-control times- cale[J]. Proceedings of the CSEE, 2017, 37(14): 3963-3972, 4274. [14] 张琛, 蔡旭, 李征. 电压源型并网变流器的机-网电气振荡机理及稳定判据研究[J].中国电机工程学报, 2017, 37(11): 3174-3183, 3372. Zhang Chen, Cai Xu, Li Zheng.Stability criterion and mechanisms analysis of electrical oscillations in the grid-tied VSC system[J]. Proceedings of the CSEE, 2017, 37(11): 3174-3183, 3372. [15] Zhao Mingquan, Yuan Xiaoming, Hu Jiabing, et al.Voltage dynamics of current control time-scale in a VSC-connected weak grid[J]. IEEE Transactions on Power Systems, 2016, 31(4): 2925-2937. [16] 刘其辉, 洪晨威, 逄思敏, 等. 基于弹性系数的双馈风电机组控制参数对次同步振荡作用分析及调整方法[J]. 电工技术学报, 2022, 37(14): 3528-3541. Liu Qihui, Hong Chenwei, Pang Simin, et al.Analysis and adjustment method of doubly-fed fan control parameters on subsynchronous oscillation based on impedance elastic sensitivity[J]. Transactions of China Electrotechnical Society, 2022, 37(14): 3528-3541. [17] 王一珺, 王海风. 并网直驱风电场在交流电流时间尺度下的小干扰稳定性—功率控制外环影响[J]. 高电压技术, 2022, 48(4): 1411-1421. Wang Yijun, Wang Haifeng.Small-disturbance stabi- lity of grid-connected PMSG wind farms under AC current time scales-the influence of power control outer loop[J]. High Voltage Engineering, 2022, 48(4): 1411-1421. [18] Li Sheng, Yan Yabing, Yuan Xiaoming.SISO equi- valent of MIMO VSC-dominated power systems for voltage amplitude and phase dynamic analyses in current control timescale[J]. IEEE Transactions on Energy Conversion, 2019, 34(3): 1454-1465. [19] 刘取. 电力系统稳定性及发电机励磁控制[M]. 北京: 中国电力出版社, 2007. [20] 王锡凡. 现代电力系统分析[M]. 北京: 科学出版社, 2003. [21] Zhang Yang, Huang S H F, Schmall J, et al. Evaluating system strength for large-scale wind plant integr- ation[C]//2014 IEEE PES General Meeting Con- ference & Exposition, National Harbor, MD, USA, 2014: 1-5. [22] 朱凌志, 曲立楠, 刘纯, 等. 新能源发电集群的改进等效短路比计算方法[J]. 电力系统自动化, 2021, 45(22): 74-82. Zhu Lingzhi, Qu Linan, Liu Chun, et al.Improved calculation method of equivalent short-circuit ratio for power generation cluster of renewable energy[J]. Automation of Electric Power Systems, 2021, 45(22): 74-82. [23] Zhu Jianhang, Guo Zeren, Hu Jiabing, et al.Trun- cation number selection of harmonic state-space model based on the Floquet characteristic expo- nent[J/OL]. IEEE Transactions on Industrial Elec- tronics.https://ieeexplore.ieee.org/document/9772947.
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