Pscc 2008 Survey Paper - Part 2 Integrated Ac/dc Transmission Systems – Benefits of Power Electronics for Security and Sustainability of Power Supply

Deregulation and privatization as well as the increase use of renewable energy are posing new challenges on high voltage transmission systems. Environmental constraints, such as energy saving, loss minimization and CO2 reduction, will also play an important role. The loading of existing power systems will further increase, leading to bottlenecks and reliability problems. High voltage power electronics, such as HVDC (High Voltage Direct Current) and FACTS (Flexible AC Transmission Systems) provide the necessary features to avoid technical problems in heavily loaded power systems; they increase the transmission capacity and system stability very efficiently, and they assist in prevention of cascading disturbances. Therefore, the strategies for the development of large power systems go clearly in the direction of hybrid transmissions, consisting of integrated DC/AC interconnections and point-to-point bulk power transmission “highways” (AC and DC backbones), including FACTS. Such hybrid systems offer significant advantages, both technical and economical as well as in terms of system security. They offer reduction in transmission costs as well as the possibility of bypassing heavily loaded AC systems.