A Review of Aging Models for Electrical Insulation in Power Cables

Abstract

Electrical insulation is an integral part of power components. The aging of electrical insulation is an undeniable fact that limits the operational lifetime of power components. Apart from regular aging, abnormal stresses and the development of defects are real threats because of their contribution in accelerating the aging rate and thereby leading to a premature failure of the power components. Over the decades, various studies have been carried out to understand the aging behavior of electrical insulation mainly considering electrical and thermal stresses. Similarly, a number of mathematical (aging) models have been developed based on the theoretical and experimental investigations and evidences. However, a dependable formulation of the models that can provide more practical estimation of the insulation degradation profile has not been achieved yet. This paper presents a comprehensive review of the aging models considering single and multistress conditions. Further, the paper discusses possible challenges and barricades averting the conventional models to achieve a suitable accuracy. Finally, suggestions are provided that can be considered to improve the modeling approaches and their performance.

A novel approach towards parametric assessment of reliability and resilience of high voltage mica‐based insulation systems by statistical analysis of experimental failure data

“…where t is time to failure, U r (E) and U b (E) are activation energies for bond formation and breakage. N is the total breakable bonds, n represents bonds already broken, n c is the critical broken bond count leading to failure, and finally h and k B are Planck's and Boltzmann's constants [42]. HV machine design and industry data provide enough evidence to consider failure at time zero as…”

“… $$$t=\int \nolimits_{N}^{{n}_{\mathrm{c}}}{\left\{\frac{{k}_{\mathrm{B}}T}{h}\left[\left({\mathrm{e}}^{\left(\tfrac{-{U}_{\mathrm{r}}(E)}{{k}_{\mathrm{B}}T}\right)(N-n)}-{\mathrm{e}}^{\left(\tfrac{-{U}_{\mathrm{b}}(E)}{kT}\right)(n)}\right)\right]\right\}}^{-1}\hspace*{.5em}dn$$$ where t is time to failure, U r ( E ) and U b ( E ) are activation energies for bond formation and breakage. N is the total breakable bonds, n represents bonds already broken, n c is the critical broken bond count leading to failure, and finally h and k B are Planck's and Boltzmann's constants [42]. HV machine design and industry data provide enough evidence to consider failure at time zero as not a typical event, suggesting that the Weibull model should have an offset value.…”

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“…frame stratification [17], -increase in resistance and short circuit in cells [18], -shading of panels [19], -junction box failure [20], -PV panels aging [21], -a fire in the installation caused by a short circuit [22], -degradation of cables insulation [23], -improper operational conditions [24], -no lightning protection or overvoltage [25],…”

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“…In this article, dielectric loss tangent (tan δ) of single and series SR and ER specimens have been investigated. Seifert et al (1998) reported dielectric measurements which showed material damages due to electrical overstresses such as those discussed by Choudhary et al (2022) and Ediriweera et al (2020), respectively, and developed an effective tool to detect and classify the ageing in composite polymeric insulations. These were the results of the interactions at the large internal filler surfaces showing an increment in the conductivity and intensification of interfacial polarizations.…”