利用波前信息的直流输电线路超高速保护原理

Principle of Ultra-high-speed Protection for DC Transmission Line Using Wave Front Information

高压直流输电对继电保护的快速动作提出要求。直流输电线路发生故障后,故障点电气量产生大量高频信号并向线路两端传播,受到输电线路参数频变特性的影响,保护测得的故障高频信号中包含故障信息。基于输电线路参数频变特性和故障点行波宽频特性分析了行波波前包含的故障信息,得出了故障零模电流行波波前形状变化程度与故障距离有关,故障零模电流行波波前幅值和过渡电阻有关的结论,据此提出了一种利用波形相关系数的直流输电线路超高速保护原理。仿真验证了该原理的快速性、可靠性和高耐过渡电阻能力。

HVDC transmission raises demand for highspeed operation of relay. When a fault occurs, a large number of high-frequency signals are generated and transmitted to both ends of transmission line. Due to frequency-dependent characteristics of transmission line parameters, the high-frequency signals of the fault contain fault information. In this paper, the fault information contained in traveling wave front was analyzed on the basis of frequency-dependent characteristics of the transmission line parameters and broadband characteristics of fault point waveform. It is concluded that shape change of fault zero-mode current wave front is related to fault distance and the magnitude of fault zero-mode current wave front is related to fault resistance. Hence, a principle of ultra-high-speed protection for DC transmission line using waveform correlation coefficient is proposed. The simulation results show that the proposed method is fast, reliable and capable of anti-high transition resistance.