Performance analysis of HTS cables with variable load demand

Currently, most of the transmission line infrastructure are being considered for an overhaul due to aging, detrition and overloaded. In light of this, the authors believe it is a good time for investing in a new technology so that the network can truly meet most of the challenges. High Temperature Superconductive (HTS) cable has a unique characteristic of low impedance to current flow. Unlike conventional power cables, HTS cable offers higher power transfer with minimum losses and more compact design of power applications yet better power flow absorption in the networks at the same voltage levels. In attempts to closely study the effect of HTS cable on power networks, several pilot projects have been carried out around the world. Promising results are achieved in terms of cable capacity and reliability. However, the big challenge of this technology is the high cost of superconductive materials in addition to the cost associated with cooling the cable, which is required at its normal operation temperature (-208°C for present HTS cables). A new cable was developed by Ultera, utilises the cryogenic electrical insulator, together with highreliable cable cooling technology that aims at a long service life, have significantly reduced the cost of HTS cable technology. The future will witness further reduction in the cost of HTS cable, certainly when industry scale production commences. This paper will present the technology in HTS cable and its anticipated effects on power transmission networks. For the last few decades power transmission for long distance was only possible with extra high voltage. However the transmission network required huge investment in high voltage equipment and switch-gear, yet it came with big electrical transmission losses. Fast growing cities and deregulation of the electrical sector in many countries around the world resulted in overwhelming demand for more power [1]. So far, the focus of the Australian electricity market has been narrowed onto the generation part of the power network, directing much of power investment into the new way of generation and renewable energy technology. This leaves the transmission part of the network with the burden of ageing and overloading to face reliability challenges in spite of this HTS cables have the potential for increasing power transmission capacity. Therefore, by transferring a larger amount of generated power that normally is lost in conventional power transmission cables, less generation is then required for the existing load [2]. Subsequent section of this paper describes in detail the obtained results from the load flow analysis performed on the hybrid sub-model, where four lengths of HTS cable are employed in conjunction with the conventional Cross Linked Polyethylene (XLPE) cable. The employment enabled a comparison to be drawn on the performance and impact of the HTS cable on a local Victorian distribution company Citipower network. West Melbourne Termination (WMTS) is one of the loops identified to be a potential site for future proposed HTS cable due to the predicted high load demand, current and scheduled zone substations upgrades from 22kV to 66kV.