Prospects of Bulk Power EHV and UHV Transmission

Deregulation and privatization pose new challenges for high voltage transmission systems. System elements are loaded up to their thermal limits, and power trading with fast varying load patterns is contributing to an increasing congestion. In this respect, interconnection of separated power systems may offer important technical, economical and environmental advantages. For the interconnections, innovative solutions will be essential to avoid congestion and to improve system stability. HVDC (High Voltage Direct Current) and FACTS (Flexible AC Transmission Systems) provide the necessary features to avoid technical problems in the power systems, they increase the transmission capacity and system stability very efficiently and they help to prevent cascading disturbances. HVDC and FACTS will play an important role for the system developments, leading to “Smart Grids” with better controllability of the power flows. For some countries, UHV transmission solutions with AC voltages of 1000 kV and DC systems with 800 kV are in the planning stage. This will increase the transmission capacity for AC links up to 10_GW and for DC systems up to 5 - 6 GW. UHV transmission will be applied in emerging countries like India and China, to serve their booming energy demands efficiently. In the paper, benefits of bulk power transmission solutions with HVDC and FACTS for system enhancement and grid interconnection are depicted and UHV technology issues for AC and DC are discussed. Prospects of high power electronics in future grid developments are presented.