Quantifying voltage variations on a time scale between 3 seconds and 10 minutes

There are a number of reasons for introducing additional voltage-variation indices covering the range in time scales between the flicker indices (up to a few seconds) and the slow voltage variations (10-minute rms values). This includes the need to quantify rapid voltage changes, the likely increase of voltage variations with an increasing penetration of distributed energy resources and the susceptibility of equipment against voltage variations in this range. This paper introduces the very-short-variation indices to quantify the difference between the 3-second and the 10-minute values of the rms voltage. The proposed method will only result in one additional index value for every 10-minute interval. The proposed method is applied to measurements at 10 different locations in five countries. The measurement results are consistent for these 10 locations. It is further proposed in this paper to use a 1-minute rms voltage next to the 3-second and 10-minute values. The 1-minute values give, among others, a better insight in the performance of the voltage control than the 10-minute values.