Effects of voltage sensitive loads on optimum capacitor allocation for power system

The purpose of reactive power compensation is to keep good voltage quality, minimize the energy loss or the investment of reactive compensation devices and improve the power transmission capability. In this paper, effects of voltage sensitive loads, namely, constant power, constant current and constant impedance type loads, on the voltage profile and real power loss to decide the optimal location of series or shunt capacitors are studied and discussed. Exponential modeling is used for the three types of loads in this analysis. The performance indices determined by the sensitivity of voltage variation (PIV), energy loss (PIL) and composite factors (PIVL) to the reactive power injection are used to determine the near optimum location of series capacitor (on the lines) or shunt capacitors (at the buses) taking the voltage sensitive loads into consideration. A 14 node power system is used as a numerical example for this study.