ELECTROMAGNETIC TRANSIENTS IN COMPENSATED TRANSMISSION-LINES

The present work deals with switching transients in transmission systems. The main parameters involved in the transient phenomena of a line are analyzed using the convolution integral in model coordinates. The attenuation factor and propagation coefficient in the time domain are investigated with regard to the duration of transients and during steady-state operation. A theoretical base for the proposed model is presented. The study proves the validity of the proposed model for the calculation of switching transient. The insulation level dependence of overhead transmission lines is discussed for both transmission and distribution systems. The margin of dependence is deduced according to the ratio of the spacing to the phase diameter. A computer algorithm for the calculation of transients under different conditions of compensation (series and parallel) has been developed. Both capacitive and inductive compensations are investigated. The computer program is valid for use in general cases such as the variation of the point at which the switching transients need to be calculated. The waveform of the voltage source can be varied and introduced in the program. The program reduces the computation time because of its simplicity. The rise rate of the transient voltage front as well as the time to its crest are investigated under different circuit connections. The dependence of the rise rate of the transient voltage front under series compensation as well as under parallel compensation is considered. A study of the switching angle and its effect on the rise rate of the transient voltage front is presented. The distribution of the rise rate of the voltage front along the line is evaluated. The voltage level is measured using the rise rate of the maximum value as well as from the time to crest for an AC source. The deformation of the waveform is investigated by applying the DC source for the studied line. A statistical study of the different values of the switching angles of a sinusoidal waveform appears to be needed.