Chapter 26 High Voltage Direct Current Transmission 26.1 INTRODUCTION It is true for both AC and DC transmission systems that in order to deliver bulk power over long distances in an efficient and economic manner, higher and higher voltages are being adopted. This chapter describes the drivers towards the adoption of high voltage direct current (HVDC) transmission systems such as the monopolar Cabora Bassa, Mozambique to Johannesburg, South Africa (6500 kV DC, 1,420 km, 2,000 MW) link commissioned in