Analysis of Path and Damping Characteristics of Subsynchronous Interaction Between Photovoltaic Plant and Weak AC Grid
Gao Benfeng1, Deng Pengcheng1, Liang Jifeng2, Zhao Yuhao2
1. Hebei Key Laboratory of Distributed Energy Storage and Micro-Grid North China Electric Power University Baoding 071003 China; 2. State Grid Hebei Electric Power Co. Ltd Electric Power Research Institute Shijiazhuang 050021 China
Abstract：When a large-scale photovoltaic (PV) plant is integrated into the AC grid through long transmission lines, the interaction between the PV plant and weak AC grid may make the integration face the threat of subsynchronous oscillation (SSO). However, the mechanism of the subsynchronous interaction between the PV plant and weak AC grid are unclear, and quantifying the damping characteristics of the subsynchronous interaction is difficult by the existing analysis methods. Therefore, this paper proposes a damping torque method extended to the dynamic equation of phase-locked loop (PLL) to analyze the subsynchronous interaction between the PV plant and weak AC grid. Firstly, the damping torque method is extended to the PLL dynamic equation to analyze the stability of the PV plant integrated into the weak AC grid system in the SSO mode dominated by PLL. Secondly, the linearization model of the PV plant integration and its corresponding closed-loop transfer function block diagram are derived. Based on the closed-loop transfer function diagram, the coupling relationship and interaction path between the PV plant and weak AC grid are revealed from the perspective of internal disturbance transfer, and the dynamic process of the interaction path affecting SSO mode damping is analyzed. Thirdly, through transfer function derivation, the damping path reflecting the subsynchronous interaction is separated, and the equivalent damping coefficient is used to quantify the SSO mode damping of the subsynchronous interaction. Finally, the influences of PLL control parameters, PV capacity, AC grid strength, PV plant intensity, and temperature on the damping characteristics of subsynchronous interaction are analyzed. The mechanism analysis shows that the PV plant-weak AC grid current disturbance and the grid-side voltage disturbance drive each other at the point of common coupling, forming the subsynchronous interaction path. Then, the subsynchronous interaction path will form a closed-loop damping path through the PLL in the SSO mode dominated by PLL, affecting the system SSO mode damping. Therefore, the damping contribution of the PV plant and subsynchronous interaction are quantitatively evaluated through the damping path separation. The results show that the PV plant and the subsynchronous interaction provide positive damping and negative damping to the system, respectively, resulting in the SSO of the PV plant integrated into the weak AC grid system. In addition, the subsynchronous interaction damping can be decreased by increasing the PLL proportion coefficient, AC grid strength, PV plant intensity or temperature, or decreasing the PLL integration coefficient or PV capacity, thereby improving the stability of the PV plant integrated to weak AC grid system. The following conclusions can be drawn from the theoretical analysis: (1) The subsynchronous interaction between the PV plant and weak AC grid will form the damping path through the PLL, affecting the SSO mode damping of the system. There is the SSO risk dominated by PLL in the PV plant integration. (2) The subsynchronous interaction provides negative damping to the system, which is the dominant factor for the SSO of the PV plant integration. (3) Reasonable design of system parameters according to the negative damping characteristics of subsynchronous interaction can effectively increase the SSO mode damping and better maintain the original positive damping characteristics of the PV plant.
高本锋, 邓鹏程, 梁纪峰, 赵宇皓. 光伏电站与弱交流电网间次同步交互作用路径及阻尼特性分析[J]. 电工技术学报, 2023, 38(24): 6679-6694.
Gao Benfeng, Deng Pengcheng, Liang Jifeng, Zhao Yuhao. Analysis of Path and Damping Characteristics of Subsynchronous Interaction Between Photovoltaic Plant and Weak AC Grid. Transactions of China Electrotechnical Society, 2023, 38(24): 6679-6694.
[1] 国家能源局. 2021年光伏发电建设运行情况[EB/OL]. [2022-03-09].http://www.nea.gov.cn/2022-03/09/c_ 1310508114.htm. [2] 郑超, 王士元, 张波琦, 等. 光伏高渗透电网动态频率特性及应对措施[J]. 电网技术, 2019, 43(11): 4064-4073. Zheng Chao, Wang Shiyuan, Zhang Boqi, et al.Dynamic frequency characteristics and counter- measures of power grid with highly penetrated photovoltaics[J]. Power System Technology, 2019, 43(11): 4064-4073. [3] 张金平, 汪宁渤, 黄蓉, 等. 高渗透率光伏参与电力系统调频研究综述[J]. 电力系统保护与控制, 2019, 47(15): 179-186. Zhang Jinping, Wang Ningbo, Huang Rong, et al.Survey on frequency regulation technology of power grid by high-penetration photovoltaic[J]. Power System Protection and Control, 2019, 47(15): 179-186. [4] 蔡纪鹤, 李蓓, 张永春. 基于SVPWM的光伏无功控制研究[J]. 电工技术学报, 2016, 31(24): 233-239. Cai Jihe, Li Bei, Zhang Yongchun.Research on photovoltaic reactive power control based on SVPWM[J]. Transactions of China Electrotechnical Society, 2016, 31(24): 233-239. [5] 商皓钰, 刘天琪, 卜涛, 等. 计及风电与光伏并网的电力系统运行风险评估[J]. 现代电力, 2020, 37(4): 358-367. Shang Haoyu, Liu Tianqi, Bu Tao, et al.Operational risk assessment of power system considering wind power and photovoltaic grid connection[J]. Modern Electric Power, 2020, 37(4): 358-367. [6] 张剑云. 哈密并网风电场次同步振荡的机理研究[J]. 中国电机工程学报, 2018, 38(18): 5447-5460. Zhang Jianyun.Research on the mechanism of subsynchronous oscillations of wind farms in Hami[J]. Proceedings of the CSEE, 2018, 38(18): 5447-5460. [7] 薛安成, 付潇宇, 乔登科, 等. 风电参与的电力系统次同步振荡机理研究综述和展望[J]. 电力自动化设备, 2020, 40(9): 118-128. Xue Ancheng, Fu Xiaoyu, Qiao Dengke, et al.Review and prospect of research on sub-synchronous oscillation mechanism for power system with wind power participation[J]. Electric Power Automation Equipment, 2020, 40(9): 118-128. [8] 张天翼, 王海风. 风电并入弱交流系统引发次同步振荡的研究方法综述[J]. 电力系统保护与控制, 2021, 49(16): 177-187. Zhang Tianyi, Wang Haifeng.Research methods for subsynchronous oscillation induced by wind power under weak AC system: a review[J]. Power System Protection and Control, 2021, 49(16): 177-187. [9] 谢小荣, 刘华坤, 贺静波, 等. 直驱风机风电场与交流电网相互作用引发次同步振荡的机理与特性分析[J]. 中国电机工程学报, 2016, 36(9): 2366-2372. Xie Xiaorong, Liu Huakun, He Jingbo, et al.Mechanism and characteristics of subsynchronous oscillation caused by the interaction between full- converter wind turbines and AC systems[J]. Pro- ceedings of the CSEE, 2016, 36(9): 2366-2372. [10] Liu Huakun, Xie Xiaorong, He Jingbo, et al.Subsynchronous interaction between direct-drive PMSG based wind farms and weak AC networks[J]. IEEE Transactions on Power Systems, 2017, 32(6): 4708-4720. [11] Li Chun.Unstable operation of photovoltaic inverter from field experiences[J]. IEEE Transactions on Power Delivery, 2018, 33(2): 1013-1015. [12] 陈武晖, 杨彦霁, 谢永胜, 等. 大规模光伏发电经串补并网系统次同步振荡机制[J]. 电网技术, 2021, 45(12): 4711-4721. Chen Wuhui, Yang Yanji, Xie Yongsheng, et al.SSO mechanism of large-scale PV generation connected to series-compensated power system[J]. Power System Technology, 2021, 45(12): 4711-4721. [13] 高本锋, 姚磊, 李忍, 等. 大规模光伏电站并网的振荡模式分析[J]. 电力自动化设备, 2017, 37(8): 123-130. Gao Benfeng, Yao Lei, Li Ren, et al.Analysis on oscillation modes of large-scale grid-connected PV power plant[J]. Electric Power Automation Equip- ment, 2017, 37(8): 123-130. [14] 赵书强, 李忍, 高本锋, 等. 光伏并入弱交流电网次同步振荡机理与特性分析[J]. 中国电机工程学报, 2018, 38(24): 7215-7225, 7448. Zhao Shuqiang, Li Ren, Gao Benfeng, et al.Analysis of mechanism and characteristics in sub synchronous oscillation between PV and weak AC networks[J]. Proceedings of the CSEE, 2018, 38(24): 7215-7225, 7448. [15] 赵书强, 高瑞鑫, 邵冰冰, 等. 多光伏发电单元并入弱交流电网系统的站内/站网次同步振荡特性分析[J]. 电力建设, 2021, 42(12): 49-58. Zhao Shuqiang, Gao Ruixin, Shao Bingbing, et al.Inside-plant and plant-grid sub-synchronous oscilla- tion characteristics analysis of multiple PV generation units connected to a weak AC power grid[J]. Electric Power Construction, 2021, 42(12): 49-58. [16] Du Wenjuan, Fu Qiang, Wang Haifeng.Method of open-loop modal analysis for examining the subsyn- chronous interactions introduced by VSC control in an MTDC/AC system[J]. IEEE Transactions on Power Delivery, 2018, 33(2): 840-850. [17] 甄自竞, 杜文娟, 王海风. 近似强模式谐振下高压直流输电系统引起的次同步振荡仿真研究[J]. 中国电机工程学报, 2019, 39(7): 1976-1985. Zhen Zijing, Du Wenjuan, Wang Haifeng.The simulation study on SSOs caused by the HVDC under the condition of near strong modal resonance[J]. Proceedings of the CSEE, 2019, 39(7): 1976-1985. [18] 杨明, 周林, 张东霞, 等. 考虑电网阻抗影响的大型光伏电站并网稳定性分析[J]. 电工技术学报, 2013, 28(9): 214-223. Yang Ming, Zhou Lin, Zhang Dongxia, et al.Stability analysis of large-scale photovoltaic power plants for the effect of grid impedance[J]. Transactions of China Electrotechnical Society, 2013, 28(9): 214-223. [19] 陈新, 张旸, 王赟程. 基于阻抗分析法研究光伏并网逆变器与电网的动态交互影响[J]. 中国电机工程学报, 2014, 34(27): 4559-4567. Chen Xin, Zhang Yang, Wang Yuncheng.A study of dynamic interaction between PV grid-connected inverters and grid based on the impedance analysis method[J]. Proceedings of the CSEE, 2014, 34(27): 4559-4567. [20] 张美清, 袁小明, 胡家兵. 基于自稳/致稳性的路径级数展开方法及其在含多样化电力电子装备电力系统稳定性分析中的应用[J]. 中国电机工程学报, 2021, 41(5): 1637-1655. Zhang Meiqing, Yuan Xiaoming, Hu Jiabing.Path series expansion method based on self-/en-stabilizing properties and its application in the stability analysis of power systems with diversified power electronic devices[J]. Proceedings of the CSEE, 2021, 41(5): 1637-1655. [21] Huang Yunhui, Yuan Xiaoming, Hu Jiabing, et al.DC-bus voltage control stability affected by AC-bus voltage control in VSCs connected to weak AC grids[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2016, 4(2): 445-458. [22] 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. [23] 高本锋, 刘毅, 李蕴红, 等. 直驱风电场与LCC- HVDC次同步交互作用的扰动传递路径及阻尼特性分析[J]. 中国电机工程学报, 2021, 41(5): 1713-1729. Gao Benfeng, Liu Yi, Li Yunhong, et al.Analysis on disturbance transfer path and damping characteristics of sub-synchronous interaction between D-PMSG- based wind farm and LCC-HVDC[J]. Proceedings of the CSEE, 2021, 41(5): 1713-1729. [24] Du W, Wang X, Wang H.Sub-synchronous inter- actions caused by the PLL in the grid-connected PMSG for the wind power generation[J]. International Journal of Electrical Power & Energy Systems, 2018, 98: 331-341. [25] 高本锋, 姚磊, 李忍. 弱电网下锁相环对大型光伏电站振荡模式的影响[J]. 太阳能学报, 2017, 38(12): 3302-3310. Gao Benfeng, Yao Lei, Li Ren.Influence of phase- locked loop on oscillation modes of large-scale PV power plant in weak grid[J]. Acta Energiae Solaris Sinica, 2017, 38(12): 3302-3310. [26] 刘巨, 姚伟, 文劲宇. 考虑PLL和接入电网强度影响的双馈风机小干扰稳定性分析与控制[J]. 中国电机工程学报, 2017, 37(11): 3162-3173, 3371. Liu Ju, Yao Wei, Wen Jinyu.Small signal stability analysis and control of double-fed induction generator considering influence of PLL and power grid strength[J]. Proceedings of the CSEE, 2017, 37(11): 3162-3173, 3371. [27] 韩平平, 林子豪, 夏雨, 等. 大型光伏电站等值建模综述[J]. 电力系统及其自动化学报, 2019, 31(4): 39-47. Han Pingping, Lin Zihao, Xia Yu, et al.Review on equivalent modeling of large-scale photovoltaic power plant[J]. Proceedings of the CSU-EPSA, 2019, 31(4): 39-47. [28] 董文凯, 任必兴, 王海风, 等. 适用于系统次同步振荡分析的风电场等值建模方法综述[J]. 电力工程技术, 2022, 41(4): 33-43. Dong Wenkai, Ren Bixing, Wang Haifeng, et al.Small-signal equivalent modeling methods of the wind farm and its application in sub-synchronous oscillations analysis of gird-connected wind power systems[J]. Electric Power Engineering Technology, 2022, 41(4): 33-43. [29] 黄云辉, 翟雪冰, 刘栋, 等. 弱电网下风力发电机组并网变流器直流电压稳定性机理分析[J]. 高电压技术, 2017, 43(9): 3127-3136. Huang Yunhui, Zhai Xuebing, Liu Dong, et al.Stability analysis on DC-link voltage of wind turbine grid-connected converter as integrated to weak grid[J]. High Voltage Engineering, 2017, 43(9): 3127-3136. [30] 赵书强, 李忍, 高本锋, 等. 适用于多源系统次同步振荡分析的图形化建模方法[J]. 电工技术学报, 2017, 32(14): 184-193, 228. Zhao Shuqiang, Li Ren, Gao Benfeng, et al.A graphical modeling method applied for multi-sources system subsynchronous oscillation analysis[J]. Transa- ctions of China Electrotechnical Society, 2017, 32(14): 184-193, 228. [31] 徐衍会, 曹宇平. 直驱风机网侧换流器引发次/超同步振荡机理研究[J]. 电网技术, 2018, 42(5): 1556-1564. Xu Yanhui, Cao Yuping.Research on mechanism of sub/sup-synchronous oscillation caused by GSC con- troller of direct-drive permanent magnetic syn- chronous generator[J]. Power System Technology, 2018, 42(5): 1556-1564. [32] 赵伟然, 汪海蛟, 李光辉, 等. 分布式光伏并网电压和功率因数协调控制策略[J]. 电力工程技术, 2017, 36(6): 20-26. Zhao Weiran, Wang Haijiao, Li Guanghui, et al.Voltage and power factor coordination control for distributed photovoltaic integration[J]. Electric Power Engineering Technology, 2017, 36(6): 20-26.
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