基于高压直流输电线路分布参数模型的模态电流差动保护算法

高压直流输电传输线分布电容电流会造成电流差动保护无法立即区分区内外故障，为避免保护误动作需要增加保护时间延迟和阈值，大大降低了电流差动保护的动作速度和灵敏性。为了使电流差动保护不受传输线分布电容电流影响，在基于传输线分布参数模型上考虑了正负极线路耦合特性，提出了适用于高压直流输电线路的模态电流差动保护算法。该算法以共模补偿电流作为故障识别依据，以差模补偿电流作为故障选极依据。该模态电流差动保护算法在故障期间可以进行故障选区和故障判极，且灵敏度高、动作速度快。最后通过PSCAD/EMTDC仿真验证了该保护方法的可行性和有效性。

Modal current differential protection method based on distributed parameter model of an HVDC transmission line

The distribution capacitor current of a high voltage DC transmission line will cause the current differential protection to fail to distinguish between faults within and outside the zone immediately. In order to avoid the incorrect trip of protection, the time delay and threshold need to be increased. This greatly reduces the action speed and sensitivity of current differential protection. In order not to be influenced by capacitor current of transmission line, this paper considers the coupling characteristics of positive and negative lines on the transmission line distribution parameter model, and puts forward a new mode current differential protection algorithm for a HVDC transmission line. The algorithm uses common mode compensation current as the fault identification basis and differential mode compensation current as the fault pole selection basis. This mode current differential protection can select fault zone and distinguish fault pole during the fault, with high sensitivity and high speed of movement. Finally, the feasibility and effectiveness of this protection method are verified by PSCAD/EMTDC simulation. This work is supported by the National Key Research and Development Program of China (No. 2016YFB0900600).