Recent Advances in High-Voltage Direct-Current Power Transmission Systems

The ever increasing progress of high-voltage high-power fully-controlled semiconductor technology continues to have a significant impact on the development of advanced power electronic apparatus used to support optimised operations and efficient management of electrical grids, which in many cases, are fully or partially deregulated networks. Developments advance both the high-voltage direct-current (HVDC) power transmission and the flexible alternating current transmission system (FACTS) technologies. In this paper, an overview of the recent advances in the area of voltage-source converter (VSC) HVDC technology is provided. Selected key multilevel converter topologies are presented. Control and modelling methods are discussed. A list of VSC-based HVDC installations worldwide is provided. It is confirmed that the continuous development of power electronics presents cost-effective opportunities for the utilities to exploit and HVDC remains a key technology. In particular, VSC-HVDC can address not only conventional network issues such as bulk power transmission, asynchronous network interconnections, back-to-back AC system linking and voltage/stability support to mention a few, but also niche markets such as the integration of large scale renewable energy sources with the grid.