Optimization of load with regard to thermical utilizationfor high voltage cables and extra-high voltage cables

摘要

This paper deals with determination of thernoptimum conditions for operation in order to achieve arnthermal stable system. Maximum current-carryingrncapacity is result of a heat balance, whereatrnovertemperature caused of losses in cable should notrnexceed a certain limit depending on kind of dielectric.rnDistribution of temperature depends not only onrndesign of the cable, system-configuration andrnmaximum load but also much more depending onrnenvironment of cable and on distribution of load overrntime. Thermal stable cable with impregnated paper arerncharacterized, that there is no ionization break of lossrnfactor distinct above the operating field strength. Arntotal thermal stable system has no worth mentioningrndrying out of soil. Moisture and with it thermalrnresistivity in environment of cable is maintained (soilrnconditions very moist). Especially a 400 kV-Oilpressurerncable with PPLP-insulation was investigated.rnDistribution of temperature is calculated for arnmaximum transmission power/system of 620 MVArnfor a flat and a triangle arrangement of laying with 3rnsingle core cables. Loss power per unit length isrncalculated on basis of standard IEC 287. Calculationsrnconsider skin and proximity effects and power loss inrnsheath.