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.