混合结构同塔双回超高压输电线路工频参数精确计算方法

Method of Accurate Calculating Power Frequency Parameter for Mixed Construction EHV Double Circuit Power Lines

超高压线路各相导线间距、位置差别较大,因此导线的自阻抗、自导纳互阻抗和互导纳等参数相差较大。为反映导线(避雷线)不同换位段和不同结构段物理结构对参数的影响,采用Carson公式计算导线参数,制作出不同换位段的导线参数。对不同换位段和不同结构段的线路参数采用特征模量方法解耦,计算转移矩阵;将各换位段和不同结构段的转移矩阵顺序相乘得到整条线路转移矩阵;从而计算出导线的正序阻抗、正序导纳、零序阻抗和零序导纳。通过搜寻土壤电阻率和改变修正系数使计算的导线序参数逼近精确值,最终使由该参数计算的导线正序和零序参数与实测值一致。该方法获得的普通型和紧凑型混合同塔双回线的导线参数可以为更精确的工程计算提供技术支持。

Because conductor＇ s interval and position difference of EHV/UHV power lines is large, that makes large differences of self-impedance, mutual-impedance, self-susceptance and mutual- susceptanee of conductors. By searching for proper soil＇ s resistivity and with Carson＇ s equations, according to physical construction of conductor（ grounding wire） in different transposition block,conductor parameters are calculated and data files of different transposition block are made. Calculating transfer matrix of different transposition block power lines by eign-analysis method, orderly composed transfer matrix of different transposition blocks makes transfer matrix of whole power line. Based on transfer matrix of this power line, the positive-sequence impedance, positive-sequence positive-susceptance, zero-sequence impedance and zero-sequence susceptance could be derived. Comparing the positive-parameters and zero-parameters with measured values in practice,changing soil＇ s resistivity and coefficient of correction could change conductor parameters of different transposition block power lines. Positive-parameters and zero-parameters are recalculated until un-tile they are very close to measured values in practice. It is considered conductor parameters are accurate. The power line data files made by this method can be used for engineering calculations.