同塔双回输电线路零序阻抗的测量及分析

同塔双回架空输电线路,测量I回线路零序阻抗,II回线路双端短路接地,其三相导线、地线与大地构成零序电流的通路,II回线路亦可等效为连续接地的避雷线,避雷线相当于I回线路的一个二次短路线圈,对I回线路磁场起去磁作用,引起I回线路零序阻抗幅值的降低和相角的变化.笔者理论分析同塔双回输电线路地线连续接地对零序阻抗测量结果准确...

Measurement and Analysis of the Zero Sequence Impedance of the Double Circuit Transmission Line

When the zero-sequence impedance of circuit Ⅰ of the double circuit transmission line is measured,zero-sequence induced current will flow through the path composed of overhead ground wire,earth and another circuit Ⅱ which is short connected and grounded in two ends and can be considered as shielding line with two terminals grounded,due to the mutual inductance between them.The path of those grounded lines is equivalent to a shorted secondary coil of circuit Ⅰ and cause demagnetization on its magnetic field.The measured value of zero-sequence impedance amplitude will be reduced as a result of the path formed by those grounded lines and the zero-sequence impedance angle will also be affected.Inaccuracy can be caused by this measurement error of zero-sequence impedance to relay protective setting,power flow calculation and stability analysis.This article analyzes Double Circuit Transmission Line with continuous ground zero sequence impedance grounding of the accuracy of measurement results,By EMTP of typical double-circuit transmission line tower with zero sequence impedance simulation,And analysis of the four 500 kV lines,two 220 kV lines,zero sequence impedance of the measured results,the measurement issues that should be noted,it puts forward some problems that should be paid attention to during the process of measurement and calculation.