Description of voltage fluctuations in LV power network with the use of Pst indicator and voltage fluctuation indices

The paper presents two measures of voltage variations in a power network: P_st indicator and voltage fluctuations indices. A differences between the two measures are revealed by the comparison. Also, an obnoxious voltage fluctuations in LV circuit are described. It is displayed that the measures used to characterize voltage fluctuations should enable identification of noxious receivers. The analysis of circuit properties is performed using exemplary measuring results. A periodic increases of P_st indicator value are observed (that evident the increase of obnoxiousness of voltage fluctuations). On the basis of the analysis of voltage fluctuations indices it is showed that the increases of P_st indicator value may be caused by different factors: increase of the amplitude or the frequency of voltage fluctuations. The time plots of P_st, amplitude and frequency of voltage fluctuations are compared with a time plots of maximal and minimal values of phase currents. On this basis it is proved that sources of obnoxious voltage fluctuations are supplied by the analyzed LV circuit. Moreover, a data that specify the receivers that cause the voltage variations (current variations and frequency of voltage fluctuations) are obtained.