电缆电气参数不同计算方法及其比较

Comparison of Different Methods for Calculating Electrical Parameters of Power Cables

为了能够准确、方便地计算出电力电缆的电气参数,包括电缆的电阻矩阵、电感矩阵、电容矩阵、电导矩阵以及序阻抗等,分别采用Carson-Clem公式、《电力系统建模及故障分析》中的方法以及Matlab中power_cableparam功能所用的方法进行比较,研究它们针对不同结构和不同排列方式的电缆的计算原理,并给出正序模型和零序模型中相关参数的计算方法,再以不同结构的电缆为算例验证其准确性。比较结果显示,《电力系统建模及故障分析》中的方法在计算线芯和护套间电容时存在缺陷;power_cableparam功能所用的方法计算导体自身电阻时所用的是直流电阻,未考虑集肤效应和邻近效应,且只可用于计算相互等间距的电缆,对于非等间距排列电缆和带铠装电缆不适用。结果说明Carson-Clem公式在准确性和通用性方面是最优的,采用此方法可以为电缆的后续研究提供准确、可靠的电缆参数。

To calculate the electrical parameters of power cables accurately and easily,including the resistance matrix,the inductance matrix,the capacitance matrix,the conductance matrix,and the sequence impedance,we studied and compared three methods,namely,Carson-Clem formula,the method in ＂Power Systems Modeling and Fault Analysis＂,and the ’power_cableparam’ function in Matlab.Focussing on their calculation principles,we proposed a calculating method of parameters in the positive sequence model and zero sequence model.Furthermore,the accuracy of the proposed method was verified based on calculations with different structures of the cables.Comparison results show that the method in ＂Power Systems Modeling and Fault Analysis＂ has defects on calculating the capacitance between the core and sheath of a cable,and that the ’power_cableparam’ function calculates cable resistance as DC resistance,ignoring the skin effect and proximity effect.In addition,the ’power_cableparam’ function becomes invalid when it is applied to calculate armored cables or cables in unequal spacing arrangement.Therefore,it is concluded that the Carson-Clem formula has certain advantages in accuracy and generality to calculate the electrical parameters of cables,and it can provide reliable data for further studying cable.