基于单端电流积聚量的高压直流输电线路全线速动保护

A Novel Whole-line Fast Protection Scheme Based on Single-ended Current Accumulation for HVDC Transmission Lines

传统的高压直流输电线路单端量保护存在高阻故障时灵敏度较低的问题。该文分析正向区内外故障时本端电流波形波动特征,区内故障时电流波形波动程度大于正向区外故障。提出差分电流积聚量和负变化率电流积聚量等单端电流积聚量以有效识别波形波动程度。以差分电流积聚量为动作量,负变化率电流积聚量为浮动门槛,构造浮动门槛电流积聚量判据以可靠区分正向区内外故障,并给出相关定值的整定方法。另外,利用电流突变量构造突变电流积聚量方向判据以判别故障方向,利用差分电流幅值最大值构造防雷击干扰判据以防止雷击时保护误动。仿真结果表明,该文保护在高阻故障时具有高灵敏性和快速性,线路末端经800Ω过渡电阻故障时保护动作时间不大于2.8ms。该文保护仅利用单端线路电流,对数据采样率要求不高,运用电流全量构成判据且算法计算量小,具有很强的工程实用性。

The traditional HVDC transmission lines single-ended protections have inadequate sensitivity with high resistance faults. In this paper, the fluctuation characteristics of single-ended line currents were analyzed under forward internal and external fault condition. The single-ended current accumulations such as differential current accumulation and negative change rate current accumulation were proposed to effectively identify the degree of waveform fluctuation. Taking the differential current accumulation as the operation amount and the negative change rate current accumulation as the floating threshold, a floating threshold current accumulation criterion was constructed to reliably distinguish the forward internal and external faults, and setting methods of the relevant setting values are given. In addition, the variable current accumulation directional criterion was constructed by variable current to determine the fault direction, the anti-lightning interference criterion was constructed by differential current maximum amplitude to prevent the protection from malfunctioning during lightning strike. RTDS simulation results verify the sensitivity and quickness of novel protection scheme under high fault resistance condition. The operation time of protection scheme is no more than 2.8 ms when fault with 800Ω resistance occurs at the end of line. The protection only uses the single-ended line current, which does not have a high requirement on the data sampling rate. The criterion is constituted by full-band current and the algorithm calculation is small. The protection presents promising engineering practicability.