Impact of distributed generation units on the sensivity of customers to voltage sags

While current fine electronics based equipment allow industrial processes to perform tasks that years before were impossible, they become more susceptible to the low power quality. Presently, industrial loads are coupled to networks through those electronic pieces of equipment, such as frequency inverters and soft-start devices, limiting the immunity to voltage sags. Voltage sags and swells are characterized by the network configuration (cables, length of main feeder and laterals, etc.) and by time/current curves of protection devices (such as fuses, relays and reclosers). Considering this configuration and by performing a set of simulations, it is possible to map areas surrounding the network according to the risk of such phenomena occur. When also considering a set of sensitivity curves of industrial processes, the network could be mapped not only for voltage disturbances but also for a number of disruptions (failures) expected per year at the analysed point. Embedding distributed generation in distribution networks increases the short circuit power of the analysed system. However, before installing such units, it is mandatory to perform an analysis of the protection system in order to preserve each distributed generation unit under short circuit occurrence. Aimed at decreasing disruption indexes, which pertain mostly to short circuit in line segments, insertion of embedded distributed generation units is a powerful tool for that purpose, even increasing the complexity of the protection system and curves of such devices. A case study is proposed to assess the impact of new distributed generation units in an existing electric distribution system, showing that the obtained results were satisfactory.