An example of converting voltage fluctuation indices into Pst indicator

A set of power quality measures includes Pst indicator and voltage fluctuation indices. Both of the measures describe voltage variation. They however differ in their properties. This results, among others, in different diagnostic capabilities. Because of that the power quality assessment should make use of both of the measures. One of the consequences of taking such an approach is the matter of possible recalculation of voltage fluctuation indices into Pst indicator. This paper presents an example of such recalculation. During the process a results of measurements recorded in LV power grid were used. The chosen example presents the case where the quality of Pst indicator restoration is only moderate. It is shown that the results of calculations are basically similar to real Pst indicator values. To give wider insight into the example, also maximal and minimal rms voltage values were used along voltage fluctuation indices and Pst indicator.