Enhancing the Utilization of the Cape's 765kV Cape Corridor by Series Compensation

To enhance the voltage stability limit of the Western Cape network, in the 1980's Eskom introduced 765kV technology to build additional lines into the Cape. This was because introducing more 400kV lines seemed not to yield substantial, additional transfer, and, because of its transfer potential compared to 400kV, 765kV was considered a better option for future expansions. The challenge here was that the then existing 400kV system was very well-developed, with a number of lines built in parallel. As a result, when the 765kV lines were introduced, their utilization was far less than adequate. This paper reports the results of a study that evaluated the possibility of series compensating the lines in the 765k Cape corridor. The areas dealt with here are the impact of series compensation on (1) loading of the 400kV and 765kV lines, (2) the system active power losses, and (3) voltage stability limit of the system.