Impedance Calculation of Twisted Cores in Power Lines at High Frequency by a Multi-Level PEEC Method

Power lines are essential components of the electrical grid that transport electricity from power plants to homes, businesses, and industries. These lines typically consist of core, sheath, and armor. The core is usually made of several twisted copper strands, and its complex structure leads to a difficult impedance analysis for transient analysis in lightning protection. The analytical method and numerical method are two common strategies for twisted core impedance analysis. However, the analytical method does not consider the impact of helix pitch on the eddy current, and it leads to the calculation error. It is hard for the numerical method to build the model of twisted cores with hundreds of strands. It is also time-consuming for the numerical method to solve the impedance of the complex structure at high frequency. This work proposes a multi-level PEEC method to solve the impedance of twisted cores of power lines. The method can depict the helix structure of twisted cores and can calculate the impedance within a considerable time.