Initial results of investigations into introducing new HVDC injections into the Cape network to increase transfer capacity

The early phases of the development of the Cape network entailed construction of 400 kV lines to link supplied from the generation pool in the northern part of the country, in Mpumalanga, with the loads in the Cape, i.e., the Western and Southern grids of Eskom. Once the 400kV network was matured, it became apparent that further commissioning of 400kV lines led to lesser and lesser improvements in voltage stability limit improvements. This led to consideration of 765 kV lines for further expansion. For the future, considerations are being made into introducing high voltage direct current (HVDC) systems into the Cape network to further increase its voltage stability limit to support future loads. This paper presents the results of the preliminary work to assess the techno-economic merits of introducing HVDC into the Cape. Some lessons learnt and further questions to be looked into are discussed.