Improved CUSUM algorithm for low voltage protection strategy of hybrid cascade HVDC transmission system
王业 1任旭超 1杜云龙 1崔玉1
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作者信息
1. 国网江苏省电力有限公司,江苏南京 210024
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摘要
为提高混合级联直流输电系统直流输电线路低电压保护的速动性和可靠性,提出了一种基于改进累积和(cumulative sum control chart,CUSUM)算法的新型高压直流线路低电压保护策略.当±800 kV混合级联直流输电系统的不同位置发生故障时,保护安装处所测得电气量呈现出一定的差异性.由于传统低电压保护缺乏整定依据,并有着误动风险,本文引入CUSUM算法提取不同故障时电气量差异特征,以此保证保护的可靠性.同时为了提高保护的速动性,借助分形理论,对CUSUM算法窗口进行改进,使得窗口具有自适应性,从而提高保护的速动性.利用PSCAD/EMTDC建立混合级联直流输电模型,并借助MATLAB验证所提新保护策略.仿真结果表明:所提方案能够快速可靠动作,有着良好的快速性和可靠性;可以耐受较高过渡电阻,有良好的耐受过渡电阻能力;判据依托于单端电气量,避免了通信中噪声和数据异常等干扰,可以快速识别区内、区外故障,并可靠动作.
Abstract
To enhance the speed and reliability of low-voltage protection for DC transmission lines in hybrid multi-terminal HVDC systems,a novel low-voltage protection strategy based on an improved cumulative sum (CUSUM) algorithm is proposed. When faults occur at different locations in a±800 kV hybrid multi-terminal HVDC system,the electrical quantities measured at the protection installation exhibit certain differences. Traditional low-voltage protection lacks a setting basis and has the risk of maloperation. This paper introduces the CUSUM algorithm to extract the characteristics of electrical quantity differences during different faults,thereby ensuring the reliability of protection. At the same time,to improve the speed of protection,the CUSUM algorithm window is improved with fractal theory,making the window adaptive and enhancing the speed of protection. A hybrid multi-terminal HVDC model is established using PSCAD/EMTDC,and the proposed new protection strategy is verified with MATLAB. Simulation results show that the proposed scheme can operate quickly and reliably,with good speed and reliability;it can withstand higher transition resistance and has good tolerance to transition resistance;the criterion relies on single-ended electrical quantities,avoiding interference from noise and data anomalies in communication,and can quickly identify internal and external faults and operate reliably.
关键词
混合级联直流系统/低电压保护/CUSUM/分形理论
Key words
hybrid cascade HVDC transmission system/low voltage protection/CUSUM/fractal theory
维普
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