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# “S注入法”与电压互感器的特殊接线方式

A S's Signal Injection Method and Connection Mode of Voltage Transformer

WAN Hui, HU Ke, SANG Zai-zhong

School of Electrical Engineering , Shandong University, Shandong Province, 250061.

Abstact: A series of TY protections based on the S's signal injection method have been widely applied for fault line selection and fault point location in power system in China. Several special connection modes of voltage transformer are needed to eliminate harmonic components because the diagnostic signal is injected through voltage transformer. The special connection modes are analyzed in the paper. And they not only meet the need of eliminating harmonic components but also adapt to fault line selection and fault point location by the S's signal injection method.
Keywords: Power System with Floating Neutral Point ; the S's Signal Injection Method ;Voltage Transformer; Connection Mode

0 引言

1 “S注入法”原理
“S注入法”是1993年曾提出的一种用于小电流接地系统单相接地选线定位新原理。选线原理[1]如下：
“S注入法”是利用单相接地故障时原边被短接，暂时处于不工作状态的接地相PT人为向系统注入一个特殊信号电流，用寻迹原理即通过检测、跟踪该信号电流的通路来实现接地故障选线定位。注入信号电流的基波频率f0位于工频n次谐波与n+1次谐波之间(n为正整数)。原理示意图如图1所示。

2 “S注入法”与电压互感器接线分析
TY系列选线保护在运用实践中，常常遇到电压互感器的特殊接线方式，加零序PT就是最常见的一种，其接线如图2所示。