ABB Review Special Report - ABB - ABB Group

XLPERFORMANCEHigh-voltagecable technologyBjörn Dellby, Gösta Bergman, Anders Ericsson, Johan KarlstrandDeregulation of the electricity supply markets and growing environmental awareness are creatingexciting new markets for power transmission solutions based on extruded cabletechnology. At the same time, improvements on allfronts are extending the use of XLPE (cross-linkedpolyethylene) insulated cable systems up to500 kV. Today’s cable system applications areoften competitive with overhead lines, whilenew manufacturing methods are enablingsubmarine cables with integrated opticalfibers and flexible joints to be supplied inlonger lengths than ever before. Further developmentof extruded insulation systems is alsocontributing to the success of ABB’s innovativeHVDC Light TM concept.High-voltage cable systems rated220 kV and above have becomepart of the very backbone of moderndaypower transmission infrastructure.This importance carries with it, however,a special responsibility on the partof the suppliers to ensure that thesystems exhibit the highest reliabilityand, because of the high electricalstresses at such voltage levels, that thecables and accessories are properlycoordinated.Deregulation – changing the rulesIn today’s deregulated electricity markets,the rules that used to govern generation,transmission and distributionhave changed for both the power utilitiesand the suppliers. Suddenly, it isthe customer who is in the spotlight.Accordingly, the market has to listenmore to public opinion, and there isa strong possibility that this will includea call for a less ‘visible’ T&Dinfrastructure.All the actors in this new market haveto reduce their costs and at the sametime guarantee high reliability for thetransmission and distribution systems.A likely scenario is that new cable interconnectionswill be built and operationalmargins will be utilized morefully in order to get maximum technicaland economic benefit from the electricalnetwork.Extruded cable systems have a majorpart to play in this new, competitiveenvironment, especially when it comesto replacing overhead lines with undergroundcables. XLPE cable systemscosts have decreased during the lastdecade and are likely to fall even further.At the same time, XLPE cable performancehas increased enormously.The new message is therefore thatXLPE cable systems are able to competewith overhead lines, technically, environmentallyand commercially. This isparticularly true in the voltage range of12–170 kV 1 .Extruded insulation – performanceand improvementsThe well-established trend toward asmaller insulation thickness will continue,resulting in a leaner cable withmany advantages, among them longerdispatch lengths, fewer joints, easierSpecial ReportABB Review47