Comparative study of HVAC and HVDC transmission systems
Transport of energy over long distances from remote natural sources to consumers in big cities requires technical, economic and environmental considerations. Uncertain wind flow, sunshine, faults and communication failures can compromise system safety, reliability, power quality during small signal and large scale power system oscillations. HVAC systems tackle power swing issue by electrical islanding protection schemes which would need to be revised for integrated AC/DC systems. Advent of DC transformers, CSC HVDC, VSC HVDC and MMC HVDC technologies have enabled the enhancement of power delivery and integration of renewable energy sources under smart grid vision. HVDC transmission lines are recognized as an efficient alternative to HVAC lines. HVAC system power transfer capability is limited by reactance, whereas HVDC lines can be loaded up to the conductor thermal limit. This paper reviews power transfer capabilities of HVAC, HVDC and High Phase Order (HPO) HVAC lines to compare their relative performance under diverse conditions. Techno economic analysis of converting existing AC lines into DC lines is presented. High voltage race has been analyzed in context of environmental concerns and HVDC transmission systems are concluded to be the right path to energy transition.