Reactive Power-Voltage Droop Gain Online Tuning Method of Photovoltaic Inverters for Improvement of Stable Output Power Capability in Weak Grids

doi:10.16183/j.cnki.jsjtu.2023.353

Abstract

Abstract:

The active power output capability and small signal stability in weak grids are key factors that limit stable photovoltaic (PV) power generation. To improve stably generating PV power in weak grids, an adaptive control method for PV inverters based on online tuning of the reactive power-voltage (Q-V) droop gain is proposed. First, to ensure active power output capability in weak grids, a “first optimization” method for the Q-V droop gain is proposed, considering voltage and current constraints. Then, to address stability constraints in weak grids, impedance modeling and stability analysis of the PV inverter system are conducted. A mapping relationship between the “parameter-weakest pole” is established with the weakest pole of the closed-loop system as a stability constraint based on the artificial neural network. A “second adjustment” method for the Q-V droop gain is developed at stably generating active power. Combined with the extended Kalman-filter-based grid impedance estimation, the proposed Q-V droop gain adaptive tuning method is realized. The effectiveness of the proposed adaptive control method is validated on the Modeling Tech real-time simulation platform.

Key words: adaptive control, converter, stability, photovoltaic (PV) power generation, voltage droop control, weak grid, artificial intelligence

CLC Number:

TM712
TM464

WANG Yuyang, ZHANG Chen, ZHANG Yu, WANG Yiming, XU Po, CAI Xu. Reactive Power-Voltage Droop Gain Online Tuning Method of Photovoltaic Inverters for Improvement of Stable Output Power Capability in Weak Grids[J]. Journal of Shanghai Jiao Tong University, 2025, 59(6): 845-856.

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References 25

[1]	中华人民共和国国民经济和社会发展第十四个五年规划和2035年远景目标纲要[N]. 人民日报, 2021-03-13(1).
	Outline of the people’s republic of China 14th five-year plan for national economic and social development and long-range objectives for 2035[N]. People’s Daily, 2021-03-13( 1).
[2]	林勇, 康佳乐, 余浩, 等. 大规模光伏发电经串补输电线路并网系统强迫次同步振荡机制[J]. 上海交通大学学报, 2022, 56(9): 1118-1127. doi: 10.16183/j.cnki.jsjtu.2021.415
	LIN Yong, KANG Jiale, YU Hao, et al. Mechanism of forced subsynchronous oscillation of large-scale photovoltaic power generation grid-connected system with series compensation tranmmission lines[J]. Journal of Shanghai Jiao Tong University, 2022, 56(9): 1118-1127.
[3]	邵昊舒, 蔡旭. 大型风电机组惯量控制研究现状与展望[J]. 上海交通大学学报, 2018, 52(10): 1166-1177. doi: 10.16183/j.cnki.jsjtu.2018.10.004
	SHAO Haoshu, CAI Xu. Research status and prospect of inertia control of large wind turbines[J]. Journal of Shanghai Jiao Tong University, 2018, 52(10): 1166-1177.
[4]	于琳, 孙华东, 徐式蕴, 等. 电力电子设备接入电压支撑强度量化评估指标综述[J]. 中国电机工程学报, 2022, 42(2): 499-515.
	YU Lin, SUN Huadong, XU Shiyun, et al. Overview of strength quantification indexes of power system with power electronic equipment[J]. Proceedings of the CSEE, 2022, 42(2): 499-515.
[5]	刘芳, 刘威, 徐韫钰, 等. 弱电网条件下并网逆变器控制环路稳定判据及交互作用规律分析[J]. 中国电机工程学报, 2023, 43(2): 466-482.
	LIU Fang, LIU Wei, XU Yunyu, et al. Analysis on stability criterion and interaction law of grid-connected inverter control loop under weak grid condition[J]. Proceedings of the CSEE, 2023, 43(2): 466-482.
[6]	LIU H K, XIE X R, HE J B, 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.
[7]	SHAIR J, XIE X R, LIU W, et al. Modeling and stability analysis methods for investigating subsynchronous control interaction in large-scale wind power systems[J]. Renewable & Sustainable Energy Reviews, 2021, 135: 110420.
[8]	WEN B, BOROYEVICH D, BURGOS R, et al. Analysis of D-Q small-signal impedance of grid-tied inverters[J]. IEEE Transactions on Power Electronics, 2016, 31(1): 675-687.
[9]	RYGG A, MOLINAS M, ZHANG C, et al. A modified sequence-domain impedance definition and its equivalence to the dq-domain impedance definition for the stability analysis of AC power electronic systems[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2016, 4(4): 1383-1396.
[10]	LIAO Y C, WANG X F. Stationary-frame complex-valued frequency-domain modeling of three-phase power converters[J]. IEEE Journal of Emerging & Selected Topics in Power Electronics, 2019, 8(2): 1922-1933.
[11]	曾志杰, 肖华锋, 高博, 等. 并网逆变器小信号建模简化方法与应用[J]. 中国电机工程学报, 2020, 40(21): 7002-7012.
	ZENG Zhijie, XIAO Huafeng, GAO Bo, et al. Simplified small-signal modeling method of grid-connected inverters and its applications[J]. Proceedings of the CSEE, 2020, 40(21): 7002-7012.
[12]	赵雨童, 高飞, 俞嘉浩, 等. 弱电网下VSC的多维度建模及稳定性分析[J]. 高电压技术, 2022, 48(1): 220-232.
	ZHAO Yutong, GAO Fei, YU Jiahao, et al. Multi-dimensional modeling and stability analysis of VSC connecting to weak grid[J]. High Voltage Engineering, 2022, 48(1): 220-232.
[13]	李卓城, 王杨, 唐俊苗, 等. 基于逆变器剩余容量及自适应虚拟谐波阻抗控制的孤岛微电网谐波功率分配策略[J]. 电网技术, 2023, 47(3): 1169-1185.
	LI Zhuocheng, WANG Yang, TANG Junmiao, et al. Harmonic power allocation strategy in islanded microgrid based on remaining capacity and adaptive virtual harmonic impedance control of inverter[J]. Power System Technology, 2023, 47(3): 1169-1185.
[14]	李贤育, 姚良忠, 程帆, 等. 适用于海上风电送出的DR-MMC混合直流电网自适应下垂控制策略[J]. 电网技术, 2022, 46(8): 2871-2882.
	LI Xianyu, YAO Liangzhong, CHENG Fan, et al. Self-adaptive droop control strategy of DR-MMC hybrid DC grid for offshore wind power transmission[J]. Power System Technology, 2022, 46(8): 2871-2882.
[15]	曹子恒, 肖先勇, 李媛, 等. 弱电网下LCL型并网逆变器的自适应改进前馈控制策略[J]. 高电压技术, 2020, 46(5): 1560-1570.
	CAO Ziheng, XIAO Xianyong, LI Yuan, et al. Adaptive novel feed-forward control strategy for LCL type grid-connected inverters in the weak grid[J]. High Voltage Engineering, 2020, 46(5): 1560-1570.
[16]	ZHANG C, MARDANI M M, DRAGIČEVIĆ T. Adaptive multi-parameter-tuning for online stabilization control of grid-tied VSC: An artificial neural network-based method[J]. IEEE Transactions on Power Delivery, 2022, 37(4): 3428-3431.
[17]	黄云辉, 周翩, 王龙飞. 弱电网下基于矢量控制的并网变换器功率控制稳定性[J]. 电力系统自动化, 2016, 40(14): 93-99.
	HUANG Yunhui, ZHOU Pian, WANG Longfei. Power control stability in vector control based voltage source converters connected to weak grid[J]. Automation of Electric Power Systems, 2016, 40(14): 93-99.
[18]	康勇, 林新春, 郑云, 等. 新能源并网变换器单机无穷大系统的静态稳定极限及静态稳定工作区[J]. 中国电机工程学报, 2020, 40(14): 4506-4515.
	KANG Yong, LIN Xinchun, ZHENG Yun, et al. The static stable-limit and static stable-working zone for single-machine infinite-bus system of renewable-energy grid-connected converter[J]. Proceedings of the CSEE, 2020, 40(14): 4506-4515.
[19]	YANG D S, WANG X F, LIU F C, et al. Adaptive reactive power control of PV power plants for improved power transfer capability under ultra-weak grid conditions[J]. IEEE Transactions on Smart Grid, 2017, 10(2): 1269-1279.
[20]	HASANIEN H M. An adaptive control strategy for low voltage ride through capability enhancement of grid-connected photovoltaic power plants[J]. IEEE Transactions on Power Systems, 2016, 31(4): 3230-3237.
[21]	FARDAD M, BAMIEH B. The Nyquist stability criterion for a class of spatially periodic systems[C]// Proceedings of the 44th IEEE Conference on Decision and Control. Seville, Spain: IEEE, 2005: 5275-5280.
[22]	LIU Z P, LIU J J, LIU Z. Analysis, design, and implementation of impulse-injection-based online grid impedance identification with grid-tied converters[J]. IEEE Transactions on Power Electronics, 2020, 35(12): 12959-12976.
[23]	BERG M, ALENIUS H, ROINILA T. Rapid multivariable identification of grid impedance in DQ domain considering impedance coupling[J]. IEEE Journal of Emerging & Selected Topics in Power Electronics, 2022, 10(3): 2710-2721.
[24]	ROINILA T, MESSO T, SANTI E. MIMO-identification techniques for rapid impedance-based stability assessment of three-phase systems in DQ domain[J]. IEEE Transactions on Power Electronics, 2018, 33(5): 4015-4022.
[25]	HOFFMANN N, FUCHS F W. Minimal invasive equivalent grid impedance estimation in inductive-resistive power networks using extended Kalman filter[J]. IEEE Transactions on Power Electronics, 2014, 29(2): 631-641.