基于线模电流故障分量的高压直流输电线路纵联保护方案

针对现有高压直流输电线路纵联保护受分布电容影响大，动作速度慢从而导致系统闭锁这一问题，提出了一种不受分布电容影响的高压直流输电线路方向纵联保护方案。通过分析模电流传输特性得到线模电流具有受分布电容影响小的特点。基于输电线路线模阻抗推导了区内和区外故障下线路两侧测点电流幅值特征,从而利用整流侧和逆变侧测点线模电流故障分量幅值比的差异作为保护判据，构建了区内外故障识别方案，并通过理论分析为保护阈值选取提供了依据。仿真结果表明，所提保护方案能够可靠识别区内外故障，保护动作不受分布电容影响，对采样和通信要求不高，并具有较强的耐过渡电阻能力和抗噪性。

Pilot Protection Scheme for HVDC Transmission Line Based on Fault Component of Aerial Mode Current

Aiming at the problem that the existing HVDC transmission line pilot protection is greatly affected by distributed capacitance, which leads to slow operation speed and converter blocking, an HVDC transmission line directional pilot protection scheme which is not affected by distributed capacitance is proposed. By analyzing the transmission characteristic of the mode currents, it is obtained that the distributed capacitance has a small influence on the aerial mode current. Based on the aerial mode impedance of the transmission line, the characteristics of the current amplitudes on both sides of the line with internal and external faults are derived respectively. Taking the difference in the characteristic of the amplitude ratio of the aerial mode current fault component at the rectifier and inverter measurement points as the protection criterion, an identification scheme for internal and external faults is constructed. And the theoretical analysis provides a basis for the selection of the protection operation threshold. Simulation results show that the proposed protection scheme can reliably identify internal and external faults, and the protection operation is not affected by distributed capacitance. It does not have high requirements on sampling and communication, and has strong tolerance to transient resistance and noise.