Series Compensated Lines Voltages Across Circuit Breakers and Terminals Caused by Switching

The increased use of series capacitive compensation for voltage control, stability, or loading on transmission systems had led to more extensive studies of the switching phenomenon of series compensated lines. In many EHV applications of series compensation, shunt reactors are also applied, further leading to certain unique switching phenomena. Voltages which can exist across series capacitors during very heavy load or fault conditions can be significant relative to system voltage, and therefore, can be of importance both in closing and opening lines. Analyses indicate several areas of concern not associated with non-series compensated lines including; a) protection of terminals against switching surges, b) low frequency oscillations in the shunt reactor-series capacitor circuit which may expose lightning arresters to very severe energy requirements, c) significant voltages across the circuit breaker when interrupting faulted lines. The first two areas will be discussed and the third analyzed in greater detail. The data in this paper was obtained from studies on the Transient Network Analyzer. 1 Figure 1 illustrates the system analyzed.