The transmission characteristics of gas insulated lines (GIL) over long distance

In many cases, large renewable energy sources of electrical power such as offshore wind farms will need to be connected to existing onshore transmission networks. Several gigawatts of electrical power need to be transferred from the wind farms to the grid, which requires reliable, low loss and high transmission capacity networks. Gas Insulated Transmission Lines (GILs) have higher transmission capacities, low losses, and higher overload capacities than other cable technologies which are needed to transmit offshore generated power to the mainland. This paper gives an overview of existing GIL and explores the challenges for long distance applications. Furthermore, analytical and computer models have been developed to assess the suitability of GIL and quantify the voltage, current and power transfer characteristics of the GIL with length. The paper describes the computed results of voltage, current and power profiles for a case study GIL operating at 400 kV for lengths up to 500 km.