750kV变压器保护配置及整定计算探讨

Discussion on protection configuration and setting calculation for 750 kV transformer

750 k V电网作为西北地区主网架目前正处于快速发展期。结合750 k V变压器特点,分析了差动保护与各侧后备保护的配置原则及应注意的问题。考虑到750 k V变压器差动保护配置较为完备,明确变压器区内故障主要依靠差动保护切除,而后备保护主要用于反应本侧母线及线路出口故障。协调区外出口附近故障的灵敏性、快速性与选择性的矛盾是变压器后备保护整定计算的关键。在此基础上,提出了750 k V变压器保护的整定方案,并就阻抗保护适用性、差动保护完善、后备保护简化及变压器保护自动整定等问题进行了探讨。本方案已在西北750 k V变压器保护中获得应用。

750 kV grid as the main grid of Northwest China is now in rapid development period. On the basis of the characteristics of 750 kV transformer, the protection configuration and its related problems are analyzed. Considering that the differential protection of 750 kV transformer is quite perfect, the internal fault is mainly dependent on the differential protection to remove and the backup protection is primarily responsible for external faults at the bus and the local end of the adjacent lines. To meet the requirements for sensitivity and speed at external local faults without losing selectivity is the key issue for setting calculation in transformer backup protection. Based on the above analysis, the setting calculation method for 750 kV transformer protection is proposed and the applicability of impedance protection, improvement of differential protection, simplification of backup protection and automatic setting calculation of transformer protection are discussed as well. The scheme has been successfully applied to the 750 kV transformer protection in Northwest China.