Advanced load models for voltage sag studies in distribution networks

Voltage sag characteristics derived from simulation are influenced by the models chosen for load representation. This aspect can be crucial for calculation of voltage sag indices based on the undelivered energy. Besides, load representation is a difficult task, since an accurate model has to incorporate voltage and frequency dependency, dynamic behavior, and equipment sensitivity. A random calculation of active and reactive power demands can be also required. This paper presents a summary of the work performed by the authors on load modeling for voltage sag studies using an electromagnetic transients program. A very simple test system is used to analyze and compare the behavior of the implemented load models.