This document provides an overview of the high voltage direct current (HVDC) power transmission and the advantages of using HVDC compared to high voltage alternating current (HVAC). This application report focuses on the control and protection requirements of HVDC station, products and solutions that can be leveraged during control and protection system design.

Electricity is produced by large power plants and is then carried over long distances (> 100 km) at high voltages (110 kV or more) by the transmission lines, which is stepped down to the level of the distribution network (11 kV or 415 V), bringing electric power to the consumer. Most power plants generate electricity as AC and the entire system uses AC afterwards since the voltage can be stepped up or down easily by the use of transformers. Bulk power from the generation plant is transported to consumers using transmission lines operating at high voltages. For shorter distance transmission of power (< 100 km), AC transmissions are widely preferred. When the transmission distances are longer (> 500 km), limitations are seen in using AC transmission.