Lightning performance of a real distribution network with focus on transformer protection

•Procedure for the evaluation of the lightning performance of an entire real distribution feeder.•The analysis includes the effects of direct strikes and of the shielding provided by nearby objects.•The model allows the estimation of the MTBF values of each MV/LV transformer.•The methodology is useful to achieve the desired lightning performance at affordable costs.

The paper applies a Monte Carlo procedure to evaluate the lightning performance of a real medium-voltage distribution network, which includes a number of lines, transformer stations and surge protection devices. Such a procedure allows inferring the characteristics of the statistical distributions of lightning-originated voltages at any point and at any phase of the network. The analysis presented in this paper aims at assessing the expected mean time between failures of MV/LV transformers caused by both direct and indirect lightning strikes. A heuristic technique has been specifically developed to reduce the computational effort despite the non-linear response of the network equipped with surge arresters.