Overview of high altitude wind energy harvesting system

Abstract

High Altitude Wind Power (HAWP) can supply clean energy at low cost and high capacity factor than Conventional Wind Power (CWP) system. The concept of harvesting high altitude wind power using air-borne wind turbine-cum electric generator supported by light gas filled blimp/aerostat has been proposed in the paper. An air-borne wind turbine at high altitude extracts kinetic energy from high speed streamlined wind using buoyancy provided by the blimp. Using a suitable power electronic converter (PEC), harvested electrical power is transmitted to the ground by using a tether. Blimp is tethered to the ground and provides mechanical strength to hold the blimp and the same tether consisting of electrical conductors is used for transmitting the generated electrical power. The paper outlines major components used for harvesting high altitude wind power. Transmission of the electrical power at medium voltage DC reduces the transmission loss and volume of the conducting cable. The optimal transmission voltage level that gives minimum weight of the tether has been calculated for a given power level. The proposed HAWP system requires high power density PEC, which converts low voltage AC to medium voltage DC in an airborne unit and a ground based PEC that transforms medium voltage DC to distribution level grid voltage. An air-borne PEC converter consists of a rectifier and an isolated DC-DC converter that supports the unidirectional power flow. Further, the paper also proposes the ground based grid-side PEC for distributed grid interface. In addition, comparative study between conventional wind energy harvesting system and high altitude wind energy harvesting system shows that high altitude wind power is better in terms of capacity factor, Cost of Electricity (COE), ease of construction, and power density than conventional wind power generating system.