New Overcurrent Relay Coordination Method Through Time Intervals to Enhance Microgrid Protection

Abstract

This paper presents a method to protect microgrids (MGs) through coordination of directional overcurrent relays (DOCRs). The new formulation is subjected to restrictions of pre-established time intervals to guarantee the primary and backup functions of each relay. This coordination criterion has advantages over the conventional coordination because functional independence between the relays is achieved. It is only necessary to update the setting in the relays affected by contingencies, topological changes, or during the formation of islands. The use of non-conventional curves is considered to give the flexibility necessary to meet the time intervals at each required location. Based on the results, the proposed coordination method reduces the operation time of the relays compared with that under the conventional coordination method in the power systems studied. Further simplification in the relay adjustment process under the different contingencies studied was obtained, which improved under the various operating conditions in the test systems.

Smart Protection System for Microgrids with Grid-Connected and Islanded Capabilities Based on an Adaptive Algorithm

“…A mathematical programming language (AMPL) is used in [20] for determining optimal settings for DOCRs, but the influence of DG is not assessed. As for other approaches based on consolidated algorithms, such as [8,9,26], GA may converge to local minima as demonstrated in [40]. As previously mentioned, solutions similar to the proposed APS are reported in [26,34], but additional hardware is often associated with budget constraints in practical applications.…”

“…In turn, the coordination scheme proposed in [9] can shorten the operation time of relays because it will only update the setting groups (SGs) of the elements affected by contingencies and/or topological changes. Using unconventional curves provides the system with the flexibility to achieve the required time intervals for each location.…”