A new algorithm for mixed Weibull analysis of partial discharge amplitude distributions

In this paper, an heuristic algorithm is presented for the evaluation of the parameters of additive-Weibull distributions having more than two elementary functions, which is a necessary condition when testing complex insulating structures with different partial discharge (PD) sources. The algorithm has, in principle, no limit in the number of component Weibull functions. Furthermore, it should be emphasized that it is not required to have a very close initial guess of the parameters for solution convergence, unlike other algorithms used at present. In order to check the validity of the proposed algorithm in finding the elementary components of a mixed Weibull function, many PD experimental tests have been performed on some lumped capacitance specimens in order to compare the experimental cumulative probability of pulse amplitude distributions (PAD) with the ones obtained from the Weibull analysis. In this aim, the results of the Cramer Von Mises (CVM) test performed on the experimental results are reported. Some considerations are also given in the case of testing commercial HV components having complex PAD.