超高压输电线路的自适应保护判据

Adaptive Protection Criterion for EHV Transmission Lines

电流差动保护是超高压线路主保护的首选之一,提高线路电流差动保护的可靠性和灵敏性是一个值得研究的问题。在各种正常运行状态和故障状态下,传统的电流差动保护判据中通过选取固定的制动系数获得灵敏度均较高的保护方案是比较困难的。文章提出了一种自适应保护的新判据,该判据可以根据系统的运行状态自适应地调节制动系数,提高了判据的灵敏度。西北电网长340 km的750 kV兰坪双端带电源的输电线路的EMTP仿真分析结果验证了该判据的正确性和有效性。

Current differential protection is one of the first choices for main protection of EHV transmission lines, so it is worth to research to improve the reliability and sensitivity of line current differential protection. For various normal operation modes and faulty states, it is difficult for traditional criterion of current differential protection to obtain protection scheme with higher sensitivity by mean of selecting fixed breaking coefficient. The authors propose a new criterion for adaptive protection that can adjust braking coefficient adaptively according to operation modes of power grid, thus the sensitivity of the criterion can be improved. EMTP simulation results of a certain 750 kV transmission line in Northwest China power grid, which is 340 km long and with power sources at both ends, validate the correctness and effectiveness of the proposed scheme.