Method for reliability analysis of industrial distribution systems

The method for reliability analysis of industrial distribution systems presented in this paper combines a Monte Carlo simulation with an electrical network model. The Monte Carlo simulation generates fail and restore events in stochastic components. The flexibility of the Monte Carlo simulation made it possible to include ageing of components and preventive maintenance. As industrial loads are often sensitive to short duration voltage sags, the influence of these sags had to be included in the model. This is done by using the maximum permissible voltage sag at the load nodes as an interruption criterion. The occurrence of a short-circuit and the intervention by the protection are modelled in detail. Mal-trips as well as fail-to-trip of the protection are included. The method presented in this paper is suitable for industrial (and other) distribution systems where sensitive loads are present, where maintenance of components is important and/or where the behaviour of the protection influences the reliability