Implications of applying different VAr support technologies in the Eskom transmission network with particular emphasis on the lifecycle cost

Abstract

Lifecycle cost implications of applying different VAr support technologies in the Eskom Transmission network have been investigated, taking into consideration the following VAr support options: · Plain capacitor bank. · Plain capacitor bank with expansion capability. · De-tuned capacitor bank. · C-type filter. The investigation has showed that for a 275kV 150 MVAr capacitor bank, the lifecycle cost of a C-type filter bank is 1, 73 times that of a plain capacitor bank and 1, 31 times that of a de-tuned capacitor bank, evaluated over a 20 years period. This high cost of the C-type filter bank is mainly due to the initial capital cost, as the operational cost of the de-tuned capacitor bank is higher than the other topologies. A change in the dielectric medium used for the capacitor units from PCB to all film dielectric has reduced the operational cost drastically. The performance of the C-type filter is better during inrush and transient conditions and therefore provides higher reliability. Additionally, a C-type filter has better harmonic performance, and provides harmonic damping over a range of frequencies.