基于电流控制补偿的高压直流线路快速差动保护

电流差动保护作为直流线路的后备保护,因其整定值低和延时长,会在直流控制暂态阶段失去作用。文中研究了直流控制特性对故障电流的影响机理,进一步推导了计及直流控制的直流补偿量,以削弱直流控制对差动电流的影响。同时,提出了一种基于电流控制补偿的高压直流线路快速差动保护。PSCAD/EMTDC仿真结果表明:所提保护凸显了差动电流的故障特征,具有整定值高和动作快速的特点,在各种故障条件下均能正确识别区内外故障。与传统电流差动保护相比,所提保护可在直流控制暂态阶段无延时地快速切除故障;其动作时间随直流控制补偿差动电流的增大而减小,具有一定的反时限特性,可作为高压直流线路快速后备保护。

Fast Differential Protection for HVDC Transmission Line Based on Current Control Compensation

As the backup protection of DC lines, the current differential protection will lose its function in the DC control transient process because of its small setting value and long delay. In this paper, the influence mechanism of DC control characteristics on fault current is studied, and the DC compensation considering DC control is further deduced to weaken the influence of DC control on differential current. A fast differential protection for high voltage direct current (HVDC) transmission line based on current control compensation is proposed. The results in PSCAD/EMTDC simulationshow that the proposed protection highlights the fault characteristics of differential current, has the characteristics of large setting value and fast operation, and can correctly identify the internal and external faults under various fault conditions. Compared with the traditional current differential protection, the proposed protection can quickly remove the fault in the DC control transient process without delay. Its operation time decreases with the increase of DC control compensation to differential current, which has a certain inverse time characteristic and can be used as a fast backup protection for HVDC lines.