内桥接线主变差动保护接线方式的实例分析

Example Analysis of Differential Protection Wiring Mode of Main Transformer in Internal Bridge Connection

内桥接线变电站的主变压器有分列运行和并列运行两种运行方式。分列运行时,每一条进线分别带一台降压变压器,变压器差动保护中差流为主变两侧电流,计算简单;而并列运行时,只有一条进线带两台降压变压器,变压器差动保护的差流还需叠加母联开关中的电流,这就需要特别注意母联开关处CT的接线方式。本文结合某实际运行的110 kV变电站,介绍变压器差动保护的基本原理,并以实例分析不同运行方式下变压器差动保护的接线方式及对应的动作特性。

The main transformer of the inner bridge connection substation has two modes:separate operation and parallel operation.In separate operation,each incoming line is equipped with a step﹣down transformer.The differential current of the transformer differential protection is the current on both sides of the main transformer.,The calculation is simple;while in parallel operation,there is only one incoming line with two step﹣down transformers,and the differential current of the transformer differential protection also needs to superimpose the current in the bus tie switch,which requires special attention to the CT wiring method at the bus tie switch.In this paper,combined with a 110 kV substation in actual operation,the basic principle of transformer differential protection is introduced,and the wiring mode and corresponding action characteristics of transformer differential protection under different operation modes are analyzed with examples.