摘要
【目的】为提升海上柔性低频输电线路保护速动性和可靠性,保障海上风电柔性低频输电系统安全运行,提出了一种考虑母线及模块化多电平矩阵变换器系统边界效应的高频暂态量单端高速保护方法。【方法】通过分析线路两端母线及模块化多电平矩阵变换器的等值模型,指出了线路两端边界对电压行波高频分量具有明显衰减作用,并确定明确的高频区间,揭示了不同时间条件下线路区内、区外故障的前行波、反行波高频分量差异。在此基础上,利用逐次变模态分解算法提取高频暂态分量,通过前、反行波高频能量比值表征区内外故障差异性。【结果】PSCAD/EMTDC仿真结果表明,逐次变模态分解算法能够有效提取含噪声信息中的高频信息,所提单端保护方案能够在2 ms内正确可靠识别区内、外故障,可耐受10 dB噪声及500Ω过渡电阻影响,抗过渡电阻及耐受噪声能力均超过传统单端暂态量保护方法。【结论】海上柔性低频输电线路边界对频率大于5 kHz的信号具有明显衰减效应;区内、区外故障时,故障反行波高频分量与前行波高频分量能量值具有明显差异,据此构建的保护方法动作速度远高于现有差动保护方法,且无需通信条件,能够耐受海洋环境影响,具备工程应用前景。
[Objective]To enhance the speed and reliability of protection for marine flexible low-frequency AC transmission lines and ensure the safe operation of offshore wind power flexible low-frequency AC transmission systems,highfrequency transient single-ended fast protection considering the boundary effects of busbars and modular multilevel matrix converters(M3Cs)is proposed.[Methods]By analyzing the equivalent models of busbars and M3Cs at both ends of the line,the boundaries at both ends were noted to have a significant attenuation effect on the high-frequency components of voltage traveling waves,and a clear high-frequency range was determined.The differences in the forward and backward wave highfrequency components under various time conditions for internal and external faults were revealed.Based on this,a successive mode decomposition algorithm was used to extract high-frequency transient components,characterizing the distinction between the internal and external faults through the ratio of forward to backward wave high-frequency energies.[Results]The PSCAD/EMTDC simulation results showed that the successive mode decomposition algorithm effectively extracted high-frequency information from noisy data.The proposed single-ended protection scheme accurately and reliably identified the internal and external faults within 2 ms,tolerating up to 10 dB noise and 500Ωtransition resistance,demonstrating superior resistance to transition resistances and noise compared to traditional single-ended transient-based protection methods.[Conclusions]The boundaries of marine flexible low-frequency AC transmission lines exhibit a significant attenuation effect on signals with frequencies greater than 5 kHz.For internal versus external faults,the energy values of the fault backward and forward wave high-frequency components are notably different,leading to a significantly faster action speed of the constructed protection method compared to existing differential protection schemes.This method does not require communication conditions and can withstand the impact of the marine environment,thus showing potential for engineering applications.
作者
李静正
杜晓通
李猛
LI Jingzheng;DU Xiaotong;LI Meng(Zhuhai Unitech Power Technology Company Ltd.,Zhuhai 519085,Guangdong Province,China;School of Electrical Engineering,Beijing Jiaotong University,Beijing 100044,China)
出处
《电力建设》
北大核心
2025年第8期105-115,共11页
Electric Power Construction
基金
国家自然科学基金项目(52377070)。
关键词
低频输电
高频量
逐次变模态分解
线路保护
单端量
风电
low-frequency power transmission
high-frequency quantities
successive variational mode decomposition
line protection
single-end quantities
wind power
