New models for reliability evaluation of power system components subjected to transient overvoltages

The paper discusses the problem of reliability evaluation of power system devices subjected to transient overvoltages. The problem is solved in the framework of “Stress-Strength” models, resorting to a few simplifying hypotheses, among which that a certain degree of knowledge is available about the degradation of component insulation strength with time and about the pdf of stress (overvoltage). By doing so, a novel class of reliability models is developed that can be regarded as an improvement and a generalization of a first model already put forward by the authors in previous papers. The properties of such new models are illustrated by means of some numerical applications, relevant to primary and secondary distribution cables, subjected to either switching or lightning voltage surges.