摘要
分析了电压互感器(TV)中线断线时的电气特征,即三相电压中将产生3次谐波分量,且大小相等、方向相同。试验结果表明,TV中线断线时,相电压和自产零序电压中的3次谐波幅值随TV原边输入电压增大而增大。在理论分析和模拟试验的基础上,提出了一种基于比率制动特性的TV中线断线判别新方法,在没有保护元件启动的情况下,当TV自产零序电压3次谐波幅值与三相电压最大基波幅值的比值大于比率定值时,判为TV中线断线,延时动作于报警。理论分析和现场数据表明:该方法能够真实反映TV中线断线的电气特征,可以准确判断TV中线断线,并且具有运算量小、易于程序实现等特点。
The electrical characteristic of PT with broken neutral line is analyzed:the third harmonics of three-phase voltages are enhanced,with same amplitude and direction.Test shows that,when PT neutral line is broken,the third harmonics of phase voltage and generated zero-sequence voltage increase along with the increase of input voltage.Therefore,it is proposed to identify the PT neutral line break according to the ratio of zero-sequence voltage third harmonic to maximal phase voltage.Theoretical analysis and site data indicate that,the proposed method detects PT neutral line break accurately,with small computation and suitable for programming.
出处
《电力自动化设备》
EI
CSCD
北大核心
2011年第4期100-103,共4页
Electric Power Automation Equipment