Title :
Life Estimation of HVDC Cables Under the Time-Varying Electrothermal Stress Associated With Load Cycles
Author_Institution :
Dipt. di Ing. dell´Energia Elettr. e dell´Inf., Alma Mater Studiorum-Univ. of Bologna, Bologna, Italy
Abstract :
In this paper, a new procedure is presented for life estimation of HVDC cables subjected to the time-varying electrothermal stress associated with load cycles and voltage. The electric-field inversion phenomenon in the insulation of dc cables is accounted for by updating the field profile as the temperature profile changes with the load. The thermal transients due to load cycles are modeled via the CIGRÉ transient thermal network adapted to dc cables. The life fractions lost during each cycle because of the cyclic variation of the electrothermal stress are computed via an adequate electrothermal life model for the insulation of HVDC cables. The Weibull hypothesis is made for relating cable life to failure probability. The procedure is applied to the load cycles of the prequalification test for HVDC extruded cables after CIGRÉ Technical Brochure 496 that does not consider the effect of thermal and synergistic electrothermal aging. It is thus shown that this test might be less severe than it should be.
Keywords :
HVDC power transmission; Weibull distribution; failure analysis; power cables; thermal stresses; time-varying systems; CIGRE transient thermal network; HVDC cable insulation; Weibull hypothesis; dc cable insulation; electric-field inversion phenomenon; electrothermal life model; electrothermal stress; failure probability; life estimation; load cycles; synergistic electrothermal aging; thermal transients; time-varying electrothermal stress; Cable insulation; Coaxial cables; HVDC transmission; Stress; Thermal loading; Transient analysis; DC power transmission; electrothermal effects; high-voltage direct-current (HVDC) insulation; life estimation; testing;
Journal_Title :
Power Delivery, IEEE Transactions on
DOI :
10.1109/TPWRD.2014.2352681