SURVEY PAPER 2 - PART 1 INTEGRATED AC/DC TRANSMISSION SYSTEMS - Benefits of Power Electronics for Security and Sustainability of Power Supply

Deregulation and privatization are posing new challenges to high-voltage transmission systems. Envi- ronmental constraints, such as energy saving, loss minimi- zation and CO2 reduction, will also play an increasingly more important role. The loading of existing power sys- tems will further increase which will lead to bottlenecks and reliability problems. High-voltage power electronics, such as HVDC (High Voltage Direct Current) and FACTS (Flexible AC Transmission Systems), provide the neces- sary features to avoid technical problems in heavily loaded power systems; they increase the transmission capacity and system stability very efficiently and assist in prevent- ing cascading disturbances. Therefore, the strategies for the development of large power systems go clearly in the direction of hybrid transmissions, consisting of integrated AC/DC interconnections and point-to-point bulk power transmission "highways" (AC and DC Backbones). FACTS technology is also an important part of this strat- egy. These hybrid systems offer significant advantages in terms of technology, economics and system security. They reduce transmission costs as well as help bypass heavily loaded AC systems.