Mitigation of voltage sags by a voltage conditioner

Abstract

Voltage dips occur very often in three-phase power systems. The association of a synchronous machine and a three-point choke can decrease the depth of these and maintain the load voltage within acceptable limits. Simulations are performed for two types of dips resulting from single-phase and three-phase faults. This is done using a load composed of induction machines and of constant admittances. For the first one, the equipment is able to mitigate all the dips. For the second one, more severe, curves showing the duration that can be sustained for a given depth are drawn. The effect of adding inertia to the machine is also analysed and is shown to have a positive impact. Then, the effect of changing the load is investigated. It is found that using a load with full motors or with constant power load have a negative impact.