Fast Computation Method of Energization Overvoltage in Cable Lines Based on Numerical Inverse Laplace Transform

Abstract

Currently, the research on the energization overvoltage in cable lines is mainly realized through simulation calculation. However, the operation process is complex and the computation speed is slow when using the simulation software to calculate the energization overvoltage in the whole line. This paper presents a numerical calculation method of energization overvoltage in the entire cable line, which can greatly improve the calculation speed, simplify the operation process and have accurate calculation results. The method is based on transmission line theory, modal theory, transmission line equation’s complex frequency domain solution and Numerical Inverse Laplace Transform (NILT). This method first performs phase-to-mode conversion on the cable line and converts the mutually coupled cable conductors into mutually independent propagation modes. Furthermore, each independent propagation mode is conducted by Laplace Transform to obtain the complex frequency domain of its voltage. Finally, after the NILT is performed on the voltage complex frequency domain solution of each propagation mode and the time domain solution is obtained, the energization overvoltage of the full cable is obtained through the inverse phase-to-mode conversion. This method is applied to a 330kV cable line, and the calculation speed is significantly improved. The overvoltage calculation results have a small error compared to the obtained results using the simulation software, indicating that the method has high accuracy.