Selection of the Parameters of 6- to 10-kV Cable Lines when Calculating and Simulating Transient Processes with Single-Phase Earth Faults

Abstract: It is shown that the use of models of cable lines in the calculations of transient processes for single-phase earth faults in 6- to 10-kV cable networks, the parameters of which are determined based on the reference data at a frequency of 50 Hz, can lead to gross errors in the assessment of parameters of discharge components of currents and voltages. The use of these models is allowable only when calculating the charging stage of a transient process at small distances between the site of fault and the buses of power supply, when the inductance of power supply is much higher than that of the damaged line. The use of models of cable lines in the calculations, the parameters of which are determined by the propagation speed of electromagnetic waves in the cable, is acceptable when solving problems associated with the calculations of overvoltages or effective current at a point of damage for alternating arc faults, when developing the protection against such damage and studying the effect of transient processes on the stability of protection. It is shown that, when developing methods to locate a fault remotely, the needed accuracy of the calculations of parameters of transient currents and voltages in the frequency range from several to 20 kHz can be provided only by frequency-dependent models of cable lines. © 2021, Allerton Press, Inc.