LCC-HVDC全工作区间小信号建模及稳定性分析

Small Signal Modeling and Stability Analysis of LCC-HVDC over a Full Operating Range

摘要

在不同的交流电压下，电网换相换流器高压直流系统存在不同的控制模式，如定电流、定电压、定关断角控制、低压限流控制(VDCOL)和电流偏差控制等．为研究不同交流电压、不同控制模式下的小干扰稳定性，以CIGRE HVDC标准测试模型和贵广Ⅱ工程模型作为算例，首先介绍考虑换流阀阻尼回路的dq轴换流器模型、SRF锁相环模型、MAF锁相环模型；然后根据不同交流电压下直流系统的不同控制模式给出相应的触发角传递函数，即控制系统模型；最后结合换流器模型、锁相环模型、控制系统模型、交流侧dq轴阻抗推导得到直流阻抗，在PSCAD/EMTDC电磁暂态仿真模型中对直流阻抗进行扫频验证，不同交流电压下的直流阻抗计算值和仿真模型的扫频结果吻合，证明小信号建模的正确性．根据阻抗分析法，在逆变器直流侧出口处将直流系统分为两个子系统，进而推导直流系统的闭环传递函数，以闭环传递函数的主导极点分布判断直流系统的小干扰稳定性，绘制了CIGRE模型和贵广Ⅱ工程模型不同交流电压、不同控制参数的稳定域，并对比了贵广Ⅱ工程模型不同短路比下的稳定域，采用PSCAD/EMTDC电磁暂态仿真模型验证了稳定域的准确性．分析稳定域得到以下结论：VDCOL控制和电流偏差控制启动会使直流系统的稳定性减弱；在弱交流系统下，交流电压的减小通常会使得直流系统的稳定范围减小，而在强交流系统下，交流电压的变化对直流系统稳定性的影响较小．

Abstract

Under different AC voltages, the line commutated converter high voltage direct current(LCC-HVDC) system has different control modes, including constant current, constant voltage, constant extinction angle control, voltage-dependent current order limiter(VDCOL)control, and current error control. This study uses the CIGRE HVDC standard test model and the GG-Ⅱ engineering model to investigate small signal stability under different AC voltages and different control modes. First, the dq axis converter model, considering the damping circuit of the converter valve, along with the SRF phase-locked loop model and MAF phase-locked loop model are introduced. Then, according to the different control modes of the DC system under different AC voltages, the corresponding trigger angle transfer function is given, and that is the control system model. Next, the DC impedance is derived by integrating the converter model, phase-locked loop model, control system model, and the AC-side dq axis impedance. This DC impedance is verified by frequency sweeping in the PSCAD/EMTDC electromagnetic transient simulation model. The calculated values of DC impedance under different AC voltages are in good agreement with the frequency sweeping results of the simulation model, which proves the correctness of the small signal modeling. According to the impedance analysis method, the DC system is divided into two subsystems at the DC-side outlet of the inverter, and then the closed-loop transfer function of the DC system is derived. The small signal stability of the DC system is judged by analyzing the dominant pole distribution of this closed-loop transfer function. The stability domain of different AC voltages and different control parameters of the CIGRE model and GG-Ⅱ engineering model are drawn, and the stability domain of the GG-Ⅱ engineering model under different short circuit ratios are compared. The accuracy of the stability domain is verified through the PSCAD/EMTDC electromagnetic transient simulation model. The following conclusions are obtained by analyzing the stability domain: VDCOL control and current error control will weaken the stability of the DC system. In weak AC systems, the decrease in AC voltage usually reduces the stability range of the DC system, whereas in strong AC systems, variations in AC voltage have little effect on the stability of the DC system.

关键词

电网换相换流器高压直流 / 交流电压跌落 / 稳定性分析 / 稳定域

Key words

line commutated converter high voltage direct current(LCC-HVDC) / AC voltage drop / stability analysis / stable domain

参考文献

[1] 姚良忠, 吴婧, 王志冰, 等. 未来高压直流电网发展形态分析[J]. 中国电机工程学报, 2014, 34(34):6007-6020.

[2] Yao Liangzhong, Wu Jing, Wang Zhibing, et al. Pattern analysis of future HVDC grid development[J]. Proceedings of the CSEE, 2014, 34(34):6007-6020(in Chinese).

[3] 梁旭明, 张平, 常勇. 高压直流输电技术现状及发展前景[J]. 电网技术, 2012, 36(4):1-9.

[4] Liang Xuming, Zhang Ping, Chang Yong. Recent advances in high—voltage direct—current power transmission and its developing potential[J]. Power System Technology, 2012, 36(4):1-9(in Chinese).

[5] 付强, 杜文娟, 王海风. 交直流混联电力系统小干扰稳定性分析综述[J]. 中国电机工程学报, 2018, 38(10):2829-2840, 3134.

[6] Fu Qiang, Du Wenjuan, Wang Haifeng. Small signal stability analysis of AC/DC hybrid power system: An overview[J]. Proceedings of the CSEE, 2018, 38(10):2829-2840, 3134(in Chinese).

[7] 郑乐, 吴晶, 徐衍会, 等. HVDC送端系统振荡引发受端换相失败的机理分析[J]. 电工技术学报, 2024, 39(9):2743-2754.

[8] Zheng Le, Wu Jing, Xu Yanhui, et al. Mechanism analysis of receiving end commutation failure caused by sending end oscillation in HVDC transmission system[J]. Transactions of China Electrotechnical Society, 2024, 39(9):2743-2754(in Chinese).

[9] 吴健颖, 彭茂兰, 武霁阳, 等. 兴安直流工程交直流系统谐振影响因素分析及其抑制措施[J]. 电力自动化设备, 2023, 43(2):197-202.

[10] Wu Jianying, Peng Maolan, Wu Jiyang, et al. Analysis on influencing factors and its countermeasure of resonance of AC/DC system in Xing’an DC project[J]. Electric Power Automation Equipment, 2023, 43(2):197-202(in Chinese).

[11] 贺杨烊, 郑晓冬, 邰能灵, 等. 交直流混联电网LCC—HVDC换流器建模方法综述[J]. 中国电机工程学报, 2019, 39(11):3119-3130.

[12] He Yangyang, Zheng Xiaodong, Tai Nengling, et al. A review of modeling methods for LCC—HVDC converter in AC/DC hybrid power grid[J]. Proceedings of the CSEE, 2019, 39(11):3119-3130(in Chinese).

[13] 郭春义, 宁琳如, 王虹富, 等. 基于开关函数的LCC—HVDC换流站动态模型及小干扰稳定性[J]. 电网技术, 2017, 41(12):3862-3870.

[14] Guo Chunyi, Ning Linru, Wang Hongfu, et al. Switching—function based dynamic model of LCC—HVDC station and small signal stability analysis[J]. Power System Technology, 2017, 41(12):3862-3870(in Chinese).

[15] 莫泽, 汪娟娟, 丁天皓, 等. 基于改进开关函数的LCC—HVDC直流阻抗建模及小扰动稳定性分析[J]. 电网技术, 2022, 46(11):4491-4505.

[16] Mo Ze, Wang Juanjuan, Ding Tianhao, et al. LCC—HVDC impedance modeling and small disturbance stability analysis based on improved switching function[J]. Power System Technology, 2022, 46(11):4491-4505(in Chinese).

[17] 王宾, 何小才. 经LCC—HVDC输电送出系统单端混合等值计算[J]. 中国电机工程学报, 2024, 44(14):5441-5451.

[18] Wang Bin, He Xiaocai. Single terminal mixed equivalence calculation of power transmission system via LCC—HVDC[J]. Proceedings of the CSEE, 2024, 44(14):5441-5451(in Chinese).

[19] Qi Y, Zhao H F, Fan S T, et al. Small signal frequency—domain model of a LCC—HVDC converter based on an infinite series—converter approach[J]. IEEE Transactions on Power Delivery, 2019, 34(1):95-106.

[20] 周盛宇, 汪娟娟, 刘岳坤, 等. 考虑换流阀阻尼电路的LCC—HVDC系统小信号精准建模[J]. 电网技术, 2022, 46(10):3730-3744.

[21] Zhou Shengyu, Wang Juanjuan, Liu Yuekun, et al. Small signal accurate modeling of LCC—HVDC system considering converter valve damping circuit[J]. Power System Technology, 2022, 46(10):3730-3744(in Chinese).

[22] 叶运铭, 汪娟娟, 陈威, 等. LCC—HVDC系统直流控制回路小干扰稳定性分析[J]. 电力系统自动化, 2021, 45(16):178-188.

[23] Ye Yunming, Wang Juanjuan, Chen Wei, et al. Small—signal stability analysis of DC control loop for LCC—HVDC system[J]. Automation of Electric Power Systems, 2021, 45(16):178-188(in Chinese).

[24] 陈威, 叶运铭, 周保荣, 等. 定电压与预测型定关断角控制对HVDC小干扰稳定性的影响[J]. 电力系统自动化, 2020, 44(18):98-106.

[25] Chen Wei, Ye Yunming, Zhou Baorong, et al. Influence of constant voltage control and predictive constant extinction angle control on small—signal stability of HVDC[J]. Automation of Electric Power Systems, 2020, 44(18):98-106(in Chinese).

[26] 王顺亮, 刘海军, 谢洋, 等. 基于模块化思想的LCC—HVDC改进小信号建模及交互稳定性分析[J]. 电力系统保护与控制, 2024, 52(10):84-94.

[27] Wang Shunliang, Liu Haijun, Xie Yang, et al. Improved small signal modeling and interaction stability analysis of LCC—HVDC based on modularization[J]. Power System Protection and Control, 2024, 52(10):84-94(in Chinese).

[28] 杨硕, 郭春义, 张加卿, 等. 控制链路延时对LCC—HVDC系统小信号稳定性的影响及机理分析[J]. 中国电机工程学报, 2021, 41(增1):70-79.

[29] Yang Shuo, Guo Chunyi, Zhang Jiaqing, et al. Impact of time—delay on small signal stability of LCC—HVDC system and its mechanism analysis[J]. Proceedings of the CSEE, 2021, 41(Suppl 1):70-79(in Chinese).

[30] 罗隆福, 付颖, 李勇, 等. 直流输电控制器原理及稳态特性分析[J]. 电力自动化设备, 2009, 29(1):65-69.

[31] Luo Longfu, Fu Ying, Li Yong, et al. Controller of HVDC transmission system and its steady—state performance analysis[J]. Electric Power Automation Equipment, 2009, 29(1):65-69(in Chinese).

[32] 杨汾艳, 徐政. 直流输电系统典型暂态响应特性分析[J]. 电工技术学报, 2005, 20(3):45-52.

[33] Yang Fenyan, Xu Zheng. Typical transient responses in HVDC transmission system[J]. Transactions of China Electrotechnical Society, 2005, 20(3):45-52(in Chinese).

[34] Chen X, Ma J P, Wang S L, et al. An accurate impedance model of line commutated converter with variable commutation overlap[J]. IEEE Transactions on Power Delivery, 2021, 37(1):562-572.

[35] 汪娟娟, 莫泽, 刘岳坤, 等. 基于单边调制映射函数的LCC—HVDC直流侧阻抗精确建模[J]. 电工技术学报, 2024, 39(13):3928-3942.

[36] Wang Juanjuan, Mo Ze, Liu Yuekun, et al. Accurate modeling of DC side impedance of LCC—HVDC based on single—side modulated mapping function[J]. Transactions of China Electrotechnical Society, 2024, 39(13):3928-3942(in Chinese).

[37] 刘星琪, 邹志翔, 姚屹洋, 等. 基于锁相环与电流环解耦的并网变换器稳定性控制策略[J]. 电力系统自动化, 2024, 48(19):109-119.

[38] Liu Xingqi, Zou Zhixiang, Yao Yiyang, et al. Stability control strategy for grid—connected converter based on decoupling of phase—locked loop and current loop[J]. Automation of Electric Power Systems, 2024, 48(19):109-119(in Chinese).

[39] 莫泽. 电网换相换流器高压直流输电系统阻抗建模及谐振稳定性分析[D]. 广州: 华南理工大学, 2023.

[40] Mo Ze. Impedance Modeling and Resonance Stability Analysis of LCC—HVDC[D]. Guangzhou: South China University of Technology, 2023(in Chinese).

[41] 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.

[42] 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(in Chinese).

[43] 宫泽旭. 新能源电力系统小扰动稳定性的判据适用性分析与矢量稳定性分类[D]. 杭州: 浙江大学, 2023.

[44] Gong Zexu. Stability Criterion Adaptation Analysis and Vector Stability Classification for Small—Signal Stability of Renewable Power System[D]. Hangzhou: Zhejiang University, 2023(in Chinese).

基金资助

智能电网重大专项资助项目(2030)(2024ZD0800901)

广东省自然科学基金资助项目(2024A1515010050)