A Method for Modeling Switching Overvoltages in High-voltage Lines of Underground Networks

The article presents the results of the development of a mathematical model of a cable line with distributed parameters for calculating and analyzing the switching overvoltages in high-voltage underground networks. The developed model is implemented in the MATLAB software package. The required computation accuracy is achieved by taking into account the frequency dependence of line parameters, and a significantly shorter computation time is obtained by using the numerical inverse Laplace transform. The novelty of the work lies in the use of the numerical inverse Laplace transform in modeling and in determining the factors influencing the switching overvoltages computation process when using software tools. The developed model was verified by comparing the voltage waveforms in three phases in energizing the line in the no-load mode with similar waveforms obtained using a broadband model in the EMTP software package, which is regarded as one of the most accurate modeling tools for cable lines around the world. The results have shown that in using the developed model, the computation speed is increased by 72 % compared with the broadband model. The cable line model is recommended to be used for predicting the switching overvoltages and other transients in lines requiring consideration of frequency parameters.