随着大规模风电并网，电力系统的稳定性问题也逐渐增多。而当前的主流风机为双馈风机，因此为了减少双馈风电场送出线的故障影响，确保电能的稳定输送，开展双馈风电场送出线的继电保护研究十分重要，从而提高风电系统并网的可靠性，所以本文所做工作如下：

本文首先分析了双馈风电机组的基本工作原理以及变流器的控制策略，并根据其控制策略在PSCAD/EMTDC中搭建仿真模型，研究其故障特征，发现双馈风电场送出线在故障时的特征与传统电网有明显不同，弱馈性，频率偏移以及系统阻抗不稳定都会对传统继电保护原理或工作方式带来干扰。

其次，本文提出了一种适用于双馈风电场送出线的纵联方向保护方法。根据双馈风电场送出线发生故障后系统拓扑网络结构的改变，确定保护安装处的测量电流主要与故障点注入短路电流和整个系统的等效阻抗有关。因此，通过确定两端电气量的关联性，根据不同故障的边界条件以及相模变换矩阵选择合适的分解方式，将处理后的数据利用Pearson相关性分析完成故障区域判断。最后经过双馈风电场并网模型的仿真结果表明，该方法不受双馈风电系统自身参数波动的影响，也不受故障距离，故障类型以及故障点过渡电阻大小的影响，可有效判别故障区域。

最后，由于风电系统参数的变化导致故障选相困难，会降低系统运行的稳定性，所以提出一种适用于双馈风电场送出线的线电压故障选相方法，同样根据故障后系统拓扑网络结构的改变进行分析，通过相模变换与短路故障的边界条件推导不同故障下线电压与系统阻抗之间的关系，确定不同故障类型的独有特征，利用Pearson相关性原理设计一种合理的选相方式。通过仿真结果表明，所提方法不受系统阻抗之间的影响，在不同距离，不同故障类型以及不同大小的过渡电阻下均可有效识别故障相，可以更好的提高双馈风电场并网的稳定性。

With the integration of large-scale wind power, the stability of power system is also increasing. The current mainstream wind turbine is a doubly-fed induction generator. Therefore, in order to reduce the fault impact of the doubly-fed wind farm outgoing line and ensure the stable transmission of electric energy, it is very important to carry out research on relay protection of the doubly-fed wind farm outgoing line, and to improve the reliability of the wind power system. Therefore, the work done in this paper is as follows :

Firstly, this paper analyzes the basic working principle of doubly-fed induction generator and the control strategy of converter. According to its control strategy, a simulation model is built in PSCAD / EMTDC to study its fault characteristics. It is found that the characteristics of the transmission line of doubly-fed wind farm are obviously different from those of the traditional power grid. Weak feedback, frequency offset and system impedance instability will bring interference to the traditional relay protection principle or working mode.

Secondly, this paper proposes a longitudinal direction protection method suitable for the outgoing line of doubly-fed wind farm. According to the change of the system topology network structure after the fault of the sending line of the doubly-fed wind farm, it is determined that the measured current at the protection installation is mainly related to the short-circuit current injected at the fault point and the equivalent impedance of the whole system. Therefore, by determining the correlation of electrical quantities at both ends, the appropriate decomposition method is selected according to the boundary conditions of different faults and the phase-mode transformation matrix, and the processed data are analyzed by Pearson correlation analysis to complete the fault area judgment. Finally, the simulation results of the doubly-fed wind farm grid-connected model show that the method is not affected by the fluctuation of the parameters of the doubly-fed wind power system itself, nor by the fault distance, fault type and fault point transition resistance, and can effectively identify the fault area.

Finally, due to the change of wind power system parameters, it is difficult to select the fault phase, which will reduce the stability of the system operation. Therefore, a line voltage fault phase selection method suitable for the outgoing line of doubly-fed wind farm is proposed. According to the change of system topology network structure after fault, the relationship between line voltage and system impedance under different faults is deduced by phase mode transformation and boundary conditions of short-circuit fault. The unique characteristics of different fault types are determined, and a reasonable phase selection method is designed by Pearson correlation principle. The simulation results show that the proposed method is not affected by the system impedance, and can effectively identify the fault phase under different distances, different fault types and different transition resistances, which can better improve the stability of double-fed wind farm grid connection.

[1]魏旭, 刘东, 高飞, 等. 双碳目标下考虑源网荷储协同优化运行的新型电力系统发电规划[J]. 电网技术, 2023, 47(09): 3648-3661.

[2]胡博, 谢开贵, 邵常政, 等. 双碳目标下新型电力系统风险评述：特征、指标及评估方法[J].电力系统自动化, 2023, 47(05): 1-15.

[3]郑兴. 海上风电接入及运行控制技术研究[D]. 东南大学, 2021.

[4]崔东岭, 摆念宗. 海上风电与陆上风电差异性分析(上)[J]. 风能, 2019(05): 74-76.

[5]刘伟宏. 电网规划中新能源电力接入存在问题及对策[J]. 光源与照明, 2022, (11): 155-157.

[6]张军军. 我国新能源发电并网问题及展望[J]. 工程建设标准化, 2016(11): 16-17.

[7]Yu. O S, Sh. N C. Features of the Operation of Wind Power Plants in an Electric Power System[J]. Power Technology and Engineering, 2021, 55(4): 620-624.

[8]韩璐, 李凤婷, 王春艳, 等.风电接入对继电保护的影响综述[J]. 电力系统保护与控制, 2016, 44(16): 163-169.

[9]王世杰, 胡威, 高鑫, 等. 新能源并网发电对配电网电能质量的影响研究[J]. 计算技术与自动化, 2021, 40(02): 47-52.

[10]Ul Y M H , Jakir H ,Rashidul M I , et al. Low-Voltage Ride through Capability Augmentation of DFIG-Based Wind Farms Using Series-Parallel Resonance-Type Fault Current Limiter[J]. Wind, 2021, 1(1): 20-43.

[11]Mahela P O, Gupta N, Khosravy M, et al. Comprehensive Overview of Low Voltage Ride Through Methods of Grid Integrated Wind Generator[J]. IEEE Access, 2019, 799299-99326.

[12]吴志鹏, 曹铭凯, 李银红. 计及Crowbar状态改进识别的双馈风电场等值建模方法[J].中国电机工程学报, 2022, 42(02): 603-614.

[13]谭爱国, 吴颖颖, 王传启, 等. 基于保障低压穿越能力的风电机组撬棒自适应投切策略研究[J]. 电力系统保护与控制, 2021, 49(18): 98-109.

[14]刘轩. 电力电子技术在风力发电中的应用[J]. 集成电路应用, 2023,40(11): 224-225.

[15]Blaabjerg F, Ma K. Future on Power Electronics for Wind Turbine Systems[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2013, 1(3): 139-152.

[16]Javad Z, Sahar A P. A new relaying scheme for protection of transmission lines connected to DFIG‐based wind farms[J]. IET Renewable Power Generation, 2021, 15(13): 2971-2982.

[17]郑玉平, 吕鹏飞, 李斌, 等. 新型电力系统继电保护面临的问题与解决思路[J]. 电力系统自动化, 2023, 47(22): 3-15.

[18]司新跃, 陈青, 高湛军, 等. 基于电流相角突变量方向的有源配电网保护[J]. 电力系统自动化, 2014, 38(11): 97-103.

[19]蔡文超, 杨炳元, 高敏, 等. 一种抑制双馈风机故障电流频率偏移的有效方法[J]. 可再生能源, 2018, 36(11): 1663-1669.

[20]甘繁欣, 郭春义, 程浩等. 双馈风电场等值阻抗模型在高频振荡研究中的适用性分析与评价[J]. 中国电机工程学报, 2023, 43(19): 7497-7509.

[21]文玉玲, 晁勤, 吐尔逊, 等. 关于风电场适应性继电保护的探讨[J]. 电力系统保护与控制, 2009, 37(05): 47-51.

[22]滕予非, 行武, 张宏图, 等. 风力发电系统短路故障特征分析及对保护的影响[J]. 电力系统保护与控制, 2015, 43(19): 29-36.

[23]王硕. 双馈风机虚拟同步并网控制基础理论与关键技术研究[D]. 华中科技大学, 2017.

[24]吴昊天. 基于永磁风机并网技术的微电网优化运行研究[D]. 华北电力大学(北京), 2021.

[25]毕天姝, 李彦宾, 马丽红, 等. 风场及其送出线保护配置与整定研究[J]. 电力系统保护与控制, 2014, 42(05): 45-50.

[26]刘一民, 王书扬, 李彬, 等. 逆变型新能源场站柔性直流送出系统交流线路差动保护灵敏性优化方案[J]. 电力建设, 2022, 43(01): 63-69.

[27]裴金鑫. 电网短路故障下风电并网系统的暂态稳定性分析及控制技术研究[D]. 重庆大学, 2021.

[28]姜惠兰, 李政, 张驰, 等. SMES-DFIG提高多机系统暂态功角稳定性的控制策略[J]. 高电压技术, 2021, 47(03): 993-1002.

[29]靳维. 风电场不确定性弱馈源相互作用机理与继电保护的研究[D]. 东南大学, 2020.

[30]YIN Jun, HUANG Xiaobo, QIAN Weichen. Analysis and research on short-circuit current characteristics and grid access faults of wind farms with multi-type fans[J]. Energy Reports, 2024, 11, 1161-1170.

[31]宋国兵, 陶然, 李斌, 等. 含大规模电力电子装备的电力系统故障分析与保护综述[J]. 电力系统自动化, 2017, 41(12): 2-12.

[32]姚骏, 孙鹏, 刘瑞阔, 等. 弱电网不对称故障期间双馈风电系统动态稳定性分析[J]. 中国电机工程学报, 2021, 41(21): 7225-7237.

[33]YAN Lun, YUAN Xiaoming. Positive and negative sequence control of DFIG based wind turbines and its impact on grid voltage profile concerning converter control capability[J]. The Journal of Engineering, 2017, 2017(13): 1584-1589.

[34]段文辉, 魏丽芳, 王克谦, 等. 内置Crowbar电路的双馈风电机组短路特性研究[J]. 可再生能源, 2018, 36(03): 405-410.

[35]余泽泓. 双馈风电机组Crowbar电路优化控制及故障特性研究[D]. 华北电力大学(北京), 2023.

[36]WANG Qingping, Bo Zhiqian, Ma Xiaowei, et al. Integrated protection based on multi-frequency domain information for UHV half-wavelength AC transmission line[J]. Protection and Control of Modern Power Systems, 2016, 1(1):

[37]WANG Chenqing, SONG Guobing, KANG Xiaoning, et al. Novel Transmission-Line Pilot Protection Based on Frequency-Domain Model Recognition[J]. IEEE Transactions on Power Delivery, 2015, 30(3): 1243-1250.

[38]杨国生, 樊沛林, 王聪博, 等. 基于能量分布的新能源场站送出线路纵联保护[J]. 电网技术, 2023, 47(04): 1415-1424.

[39]王春又，孙士云，毛肖，等. 适应于双馈风电场送出线的时域距离纵联方向保护[J]．电力系统保护与控制，2021，49(13)：82-94．

[40]FAN Zhanfeng, SONG Guobing, KANG Xiaowei, et al. Three-phase fault direction identification method for outgoing transmission line of DFIG-based wind farms[J]. Journal of Modern Power Systems and Clean Energy, 2019, 7(5): 1155-1164.

[41]鲁月华，樊艳芳，罗瑞．适用于交直流混联系统的时域全量故障模型判别纵联保护方案[J]．电力系统保护与控制，2020，48(19)：81-88．

[42]侯俊杰，樊艳芳．基于分布参数模型的风电系统长距离送出线时域距离保护[J]．电力系统保护与控制，2018，46(19)：26-33．

[43]YANG Qifan，MA Hongzhong，LIU Yiqing，et al．Novel pilot protection based on time‐domain for transmission line with doubly fed induction generator[J]．International Transactions on Electrical Energy Systems，2020，30(10)．

[44]CHEN Shi, TAI Nengling, FAN Chunju, et al. Adaptive distance protection for grounded fault of lines connected with doubly-fed induction generators[J]. IET Generation, Transmission Distribution, 2017, 11(6): 1513-1520.

[45]陈玉，文明浩，胡列翔，等．双馈风机风电场联络线出口故障方向判别[J]．电力系统及其自动化学报，2020，32(02)：1-6．

[46]宋国兵，王晨清，唐吉斯，等．适用于风电接入系统的时域模型识别纵联保护新原理[J]．电网技术，2016，40(11)：3580-3585．

[47]徐艳春，范钟耀，孙思涵，等．基于边缘检测的大规模风电场送出线路纵联保护算法[J]．电力自动化设备，2023，43(01)：90-99．

[48]王紫薇, 肖繁, 王友怀, 等. 适用于双馈风电场联络线故障选相方法[J]. 电力系统自动化, 2018, 42(08): 170-176.

[49]王晨清, 宋国兵, 徐海洋, 等. 适用于风电接入系统的相电压暂态量时域选相新原理[J]. 电网技术, 2015, 39(08): 2320-2326.

[50]Anudeep B, Nayak K P. Transient energy‐based combined fault detector and faulted phase selector for distribution networks with distributed generators[J]. International Transactions on Electrical Energy Systems, 2020, 30(4).

[51]XU Kehan, ZHANG Zhe, LAI Qinghua, et al. Fault phase selection method applied to tie line of renewable energy power stations[J]. IET Generation, Transmission & Distribution, 2020, 14(13): 2549-2557.

[52]黄涛, 陆于平. 适用于双馈风电场的改进电流突变量选相元件[J]. 电网技术, 2015, 39(10): 2959-2964.

[53]TANG Yaojing, CHANG Yongle, TANG Jinrui, et al. A Novel Faulty Phase Selection Method for Single-Phase-to-Ground Fault in Distribution System Based on Transient Current Similarity Measurement[J]. Energies, 2021, 14(15): 4695-4695.

[54]张俊峰, 高亮, 沈奕菲, 等. 适用于双馈机组风电场的故障电压序分量选相元件[J]. 电力系统保护与控制, 2018, 46(10): 136-143.

[55]ZHANG Jinhua, ZHANG Baohui, WANG Chenqing. Improved schemes for traditional current-based phase selectors in wind power systems[J]. IET Generation, Transmission & Distribution, 2018, 12(21): 5781-5788.

[56]XU Zhihao, LU Yuping. A Novel Superimposed Phase Selection Method for Transmission Line of DFIG-based Wind Farm[C]. //2020 12th IEEE PES Asia-Pacific Power and Energy Engineering Conference. Piscataway, NJ, IEEE, 2020: 1-5.

[57]LI Xu, LU Yuping, JIANG Wentao, et al. Compensated phase selection method based on virtual magnitude rezoning for transmission lines emanating from wind farms[J]. Electric Power Systems Research, 2022, 206.

[58]宋国兵, 常仲学, 王晨清. 大规模风电接入系统的继电保护[M]. 北京: 科学出版社, 2020: 5-11.

[59]王春又. 双馈风机接入对线路继电保护影响及保护策略研究[D]. 昆明理工大学, 2021.

[60]姜丰, 朱家玲, 胡开永, 等. Pearson相关系数评价ORC系统蒸发器特性的应用研究[J]. 太阳能学报, 2019, 40(10): 2732-2738.

[61]葛耀中. 新型继电保护和故障测距的原理与技术[M]. 西安: 西安交通大学出版社, 2007: 42-46.