Short Duration Voltage Variations (SDVVs) are momentary variations in the supply of electricity that can last from half a cycle to two minutes and are caused by several factors, such as atmospheric discharges, faults in the electrical system, large loads maneuvers and maintenance operations. The proposed method to deal with voltage sags uses cosine similarity to locate the disturbance responsible for it, either a fault or variation of large loads. The cosine of the angle between voltage and current can be calculated in the phase which the voltage drop occurs, and the result of this calculation indicates the direction of the disturbance in the system, with the aim of assigning responsibility to the concessionaire, to other adjacent industrial parks or to the company itself.
