On probabilistic system indices for voltage dips

This paper deals with system indices for characterising the performance of an entire system regarding voltage dips. System indices are calculated from the site indices obtained for a number of sites. For each site, also stochastic assessment of voltage dips is conducted adopting the method of fault positions. Such a tool is particularly valuable for characterising the power quality referred to voltage dips, that are non frequent events. Some weighted indices are also proposed and evidenced; the sensitivity of the system indices to the weights confirms that attributing weighting factors is a delicate matter that, if appropriately used, can mark the behaviours of systems.