Limitação das correntes de curto-circuito para minimizar o impacto da elevada integração de geração distribuída na proteção de alimentadores em média tensão

Abstract

With the increasing number of distributed generators connected to distribution systems, which traditionally had centralized generation, networks are now configured to allow bidirectional energy flow. This scenario has significant impacts on short-circuit currents, not only altering their magnitude but also their direction, directly affecting the effectiveness of overcurrent protections. The complexity is compounded by the fact that algorithms used by protection device manufacturers are not publicly disclosed, hindering advancements in the field of protection. This study investigates the behavior of short-circuit currents in a context of high penetration of distributed generation, considering different types of faults at specific locations on a medium-voltage distribution feeder. The technique adopted for short-circuit current detection involves defining a reference current value, reading instantaneous current values in each phase, comparing them with the reference value, and calculating the derivative using the Euler method. This approach was implemented alongside a solid-state current limiter on the IEEE 13 NTF test feeder with varying levels of power injected by distributed generators. Simulation results indicate an average detection time of approximately 250 ms. Regarding current limitation, significant variations in short-circuit current magnitudes were observed. The highest average variations were 85.01% for single-phase faults, 87.60% for two-phase faults, and 94.09% for three-phase faults