Design guide for power tapping from extra-high voltage (EHV) lines using insulated shield-wire and series compensation, with standardised components

Abstract

The technology for tapping power from Extra-high Voltage (EHV) lines by using an insulated shield-wire and series compensation, has already been developed. This technique is known as CAPTAP. The CAPTAP technology's main target area is in sparsely populated areas where people are living next to an Extra-high Voltage line and do not have the benefit of electricity. The technology can only supply approximately 50kW of power. With this low kilowatt capacity per substation and thus a very low revenue, it is essential to develop a CAPTAP system as cost-effective as possible. With the CAPT AP development up to date, a new shunt capacitor and reactor value had to be determined for each new CAPT AP substation design, without any standardisation on these components. The aim of this study is to design and build future low-cost CAPT AP substations, by using standardised components with the absolute minimum computer usage. There was a serious need to construct a CAP TAP substation in a sparsely populated area after the prototype built by Leigh Stubbs of Eskom Transmission Department in 1992. Unfortunately the Prototype CAPTAP was not situated close to any domestic customers who have not yet experienced the benefit of electricity. Eskom management agreed to subsidise a Pilot CAPT AP substation, on condition that the cost be kept as low as possible. The author took the initiative to design and construct a proper low-cost substation in an area that justifies this kind of technology. It was decided that the equipment from the prototype substation would be re-used in order to build a Pilot CAPT AP substation. Having had the opportunity of building a Pilot CAPTAP substation, the author designed a new improved off-ground level low-cost substation. With the experience gained from this field exercise, the autB~ veloped a new method of designing a CAPTAP system With 'g{andilJdised ,~J~Tpon nts and without Ot- I nc in-depth computer simulations.