Estimation of Pst indicator values on the basis of voltage fluctuation indices

Abstract

Power quality is described by voltage fluctuation measures. Voltage fluctuation is understood as “a series of voltage changes or a continuous variation of the rms or peak value of the voltage.” Voltage variation is most often manifested by flicker, which might become obnoxious at a high enough intensity. One of the standard measures of voltage fluctuation is $\boldsymbol {P}_{st}$ indicator. One of its major flaws is its limited diagnostic capabilities. Voltage fluctuation indices are the measure, which provides much bigger range of diagnostic capabilities. However, it has not been acknowledged as a standard measure. The initial part of this paper includes the description of the accepted method of reproducing voltage variation. It also presents general characteristics of the $\boldsymbol {P}_{st}$ indicator and voltage fluctuation indices. The next part of this paper describes the methods of converting voltage fluctuation indices into $\boldsymbol {P}_{st}$ indicator and vice versa. The capability of estimating the $\boldsymbol {P}_{st}$ indicator on the basis of the indices has been confirmed. Three examples of measurement results of both these measures in low-voltage (LV) power grids have been presented. These results have proved the connection between the estimated values (on the basis of voltage fluctuation indices) and the results of the $\boldsymbol {P}_{st}$ indicator measurements.