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Cape Corridor - South Africa

Series Capacitors for increased power transmission capability over the 765 kV Cape Corridor

A total of six series capacitors are coming on line in 2012 in the 765 kV national grid in South Africa, supplied and installed by ABB. The installations, which form part of an initiative to increase power transmission capacity to the Cape region, will allow Eskom, the national power utility, more flexibility and
reduce its reliance on existing local power generation. The ratings of the series capacitors range from 450 Mvar up to more than 1300 Mvar.

The Cape Corridor is a portion of the transmission network that stretches from Mpumalanga down to the Western Cape, approximately 1400 km. The large distance and loading require very high voltages and hence the corridor has 765 kV and 400 kV transmission lines, the current 765 kV network extending half way along the corridor.

With series capacitors, the transmission capability of already existing power systems can be increased considerably, thereby decreasing the need for new lines in cases where the demand for power transmission capacity has grown. Likewise, in green-field projects, the amount of transmission lines to
accomodate a certain amount of power transmission can be kept to a minimum. 

The series capacitors are located at four sites along the Cape Corridor (Fig. 1):

  • Alpha 1 & 2, each rated at 446 Mvar
  • Beta 1 & 2, each rated at 1340 Mvar
  • Perseus, rated at 893 Mvar
  • Mercury, rated at 1119 Mvar
 

Main data

(Alpha & Beta only) Alpha (per SC) Beta (per SC)
Commissioning year: 2012 2012
System voltage (kV) 765 765
Rated reactive power (Mvar): 446 1340
Rated capacitor current (A): 3150 3150
Rated capacitor reactance (Ω): 15.0 2x22.5
Installed MOV, including 10% redundancy (MJ/phase) 20.9 2x25.4

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