1
Transient AC overvoltage suppression orientated reactive power control of the wind turbine in the LCC-HVDC sending grid
LCC-HVDC送电电网中面向暂态交流过压抑制的风电机组无功控制
Bo Pang; Xiao Jin; Quanwang Zhang; Yi Tang; Kai Liao; Jianwei Yang; Zhengyou He
B. Pang et al., "Transient AC overvoltage suppression orientated reactive power control of the wind turbine in the LCC-HVDC sending grid," in CES Transactions on Electrical Machines and Systems, doi: 10.30941/CESTEMS.2024.00020.
Abstract—High-voltage direct current (HVDC) transmission is a crucial way to solve the reverse distribution of clean energy and loads. The line commutated converter-based HVDC (LCC-HVDC) has become a vital structure for HVDC due to its high technological maturity and economic advantages. During the DC fault of LCC-HVDC, such as commutation failure, the reactive power regulation of the AC grid always lags the DC control process, causing overvoltage in the AC sending grid, which brings off-grid risk to the wind power generation based on power electronic devices. Nevertheless, considering that wind turbine generators have fast and flexible reactive power control capability, optimizing the reactive power control of wind turbines to participate in the transient overvoltage suppression of the sending grid not only improves the operational safety at the equipment level but also enhances the voltage stability of the system. This paper firstly analyses the impact of wind turbine's reactive power on AC transient overvoltage. Then, it proposes an improved voltage-reactive power control strategy, which contains a reactive power control delay compensation and a power command optimization based on the voltage time series prediction. The delay compensation is used to reduce the contribution of the untimely reactive power of wind turbines on transient overvoltage, and the power command optimization enables wind turbines to have the ability to regulate transient overvoltage, leading to the variation of AC voltage, thus suppressing the transient overvoltage. Finally, the effectiveness and feasibility of the proposed method are verified in a ±800kV/5000MW LCC-HVDC sending grid model based on MATLAB/Simulink.
摘要—高压直流输电是解决清洁能源与负荷逆向分配的重要途径。基于线路换流器的HVDC（LCC-HVDC）以其技术成熟和经济优势成为HVDC的一种重要结构。在LCC-HVDC发生换相失败等直流故障时，交流电网的无功调节总是滞后于直流控制过程，造成交流送出电网过电压，给基于电力电子器件的风力发电带来离网风险。然而，考虑到风力发电机组具有快速灵活的无功控制能力，优化风力发电机组的无功控制以参与送出电网的暂态过电压抑制，不仅提高了设备层面的运行安全性，而且增强了系统的电压稳定性。本文首先分析了风力机无功功率对交流暂态过电压的影响。在此基础上，提出了一种改进的电压无功控制策略，包括无功控制延时补偿和基于电压时间序列预测的功率指令优化。采用时延补偿的方法来降低风力机不及时无功功率对暂态过电压的贡献，功率指令优化使风力机具有调节暂态过电压的能力，从而引起交流电压的变化，从而抑制暂态过电压。最后，在基于MATLAB/Simulink的±800kV/5000MW LCC-HVDC送出电网模型中验证了该方法的有效性和可行性。
2
A loss-model-based efficiency optimization control method for induction traction system of high-speed train under emergency self-propelled mode
基于损失模型的高速列车感应牵引系统紧急自走模式效率优化控制方法
Yutong Zhu; Yaohua Li
Y. Zhu and Y. Li, "A loss-model-based efficiency optimization control method for induction traction system of high-speed train under emergency self-propelled mode," in CES Transactions on Electrical Machines and Systems, doi: 10.30941/CESTEMS.2024.00017.
Abstract—Increasing attention has been paid to the efficiency improvement of the induction traction system of high-speed trains due to the high demand for energy saving. In emergency self-propelled mode, however, the dc-link voltage and the traction power of the motor are significantly reduced, resulting in decreased traction efficiency due to the low load and low speed operations. Aiming to tackle this problem, a novel efficiency improved control method is introduced to the emergency mode of high-speed train traction system in this paper. In the proposed method, a total loss model of induction motor considering the behaviors of both iron and copper loss is established. An improved iterative algorithm with decreased computational burden is then introduced, resulting in a fast solving of the optimal flux reference for loss minimization at each control period. In addition, considering the parameter variation problem due to the low load and low speed operations, a parameter estimation method is integrated to improve the controller's robustness. The effectiveness of the proposed method on efficiency improvement at low voltage and low load conditions is demonstrated by simulated and experimental results.
摘要—高速列车感应牵引系统的节能要求越来越高，其效率的提高也越来越受到人们的重视。然而，在紧急自推进模式下，直流环节电压和电机牵引功率显著降低，导致牵引效率下降，这是由于低负荷和低速运行。针对这一问题，本文将一种新的效率改进控制方法引入高速列车牵引系统的应急模式。在该方法中，建立了考虑铁耗和铜耗行为的异步电动机总损耗模型。在此基础上，提出了一种改进的迭代算法，减少了计算量，从而快速地求解出每个控制周期的最优磁链参考值，使损耗最小。此外，针对低负荷低速运行时参数变化的问题，提出了一种参数估计方法，以提高控制器的鲁棒性。仿真和实验结果验证了该方法在低电压、低负载条件下提高效率的有效性。
《中国电工技术学会电机与系统学报（英文）》(CES TEMS)是中国电工技术学会和中国科学院电工研究所共同主办、IEEE PELS学会技术支持的英文学术期刊。期刊发表国内外有关高性能电机系统、电机驱动、电力电子、可再生能源系统、电气化交通等研发及应用领域中原创、前沿学术论文。中国工程院院士马伟明担任主编，IEEE的执委Don Tan博士为国际主编。目前已被EI、Scopus、 Inspec、Google scholar、IEEE Xplore、中国科学引文数据库(CSCD) 核心版、DOAJ、CSTPCD、知网、万方、维普等数据库收录。
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