Evaluation of voltage dip severity based on lost voltage-time area

Nowadays, the ITIC curve is commonly used for evaluating voltage dips´ severity. However, this curve may not catch equipment sensitivity well enough and it certainly lacks the information about the probability of whether any equipment is indeed switched on or not. In this paper we present a novel voltage dip severity evaluation method based on the lost voltage-time area of the dip and also give detailed insight into the generalization of this method based on fuzzy logic. To compare the different methods used in the industry, the ones found in the literature and ours with each other, a voltage dip evaluator program was written in MATLAB and the methods were tested against each other by using voltage dip measurement data received from the local DSO. The probability of whether any equipment is switched on or not is also investigated by using a so-called on-period curve that was determined by taking average household consumption data into consideration.