The rapid growth of the South African economy since 2003 has greatly increased the demand for essential resources, including energy. As a result, Eskom has not only had to increase the generation of electricity, but also to strengthen its transmission network.

To accomplish the above tasks, various technical options and alternatives have been identified. One of these is HVDC (high-voltage direct current) transmission. In particular, the novel use of ±800kV DC as the operating voltage for the transport of large blocks of power over long distances is being investigated.

DC transmission at ±800kV has never been used operationally anywhere in the world, apart from a scheme (now operating at reduced voltage) in Russia and prospective systems in India and China. Although their experience will certainly help Eskom, the very different local conditions (severe lightning, high altitudes, acute insulator pollution, rampant fires, etc) and unproven voltage make local research, development, and testing essential.

To meet Eskom’s current operational objectives and to position the organisation as a leader in HVDC technology and application, ERID has already embarked on various research initiatives, including (but not limited to):

• Apollo-Cahora Bassa upgrade to ±600kV, 3 500A
• solving existing operational problems (Apollo-Cahora Bassa)
• practical telecommunications media for long-distance transmission, up to 3 000km
• 1,2MV HVDC testing facility
• regional initiatives in HVDC, such as the Caprivi project
• AC/DC line conversions
• original HVDC research

The research being conducted by ERID will greatly contribute to the development and growth of local technical expertise in DC technology, especially regarding DC insulation and line design. It will also improve Eskom’s image and competitiveness as a competent user of HVDC technology.