Microgrid Protection through Adaptive Overcurrent Relay Coordination

Abstract

The inclusion of distributed energy resources (DER) in Microgrids (MGs) comes at the expense of increased changes in current direction and magnitude. In the autonomous mode of MG operation, the penetration of synchronous distributed generators (DGs) induces lower short circuit current than when the MG operates in the grid-connected mode. Such behavior impacts the overcurrent relays and makes the protection coordination difficult. This paper introduces a novel adaptive protection system that includes two phases to handle the influence of fault current variations and enable the MG to sustain its operation. The first phase optimizes the power flow by minimizing the generators’ active power loss while considering tolerable disturbances. For intolerable cases, the second phase opts to contain the effect of disturbance within a specific area, whose boundary is determined through correlation between primary/backup relay pairs. A directional overcurrent relay (DOCR) coordination optimization is formulated as a nonlinear program for minimizing the operating time of the relays within the contained area. Validation is carried out through the simulation of the IEEE 9, IEEE 14, and IEEE 15 bus systems as an autonomous MG. The simulation results demonstrate the effectiveness of our proposed protection system and its superiority to a competing approach in the literature.

Comparative framework for AC-microgrid protection schemes: challenges, solutions, real applications, and future trends

“…In general, digital relays of different setting groups are more suited to this form of protection, together with intelligent controllers and efficient communication routes for sharing regulating signals in centralized or decentralized frameworks [58][59][60]. Reference [61] proposes a hybrid (centralized/decentralized) scheme using IEC 61,850-based smart electronic devices to reduce the computational burden and capabilities of controllers, whereas [62] employs a wide-area wireless network based on WiMAX concepts to alleviate data transfer uncertainties.…”

Adaptive Central Control Scheme and Investigation of Fault Current Contribution for Protection of Microgrid

“…Ankan Chandra,et al, [12]proposed in which instantaneous and inverse time relay is used through main protection and backup protection are achieved. V. Vinod et al, [13] proposed a relaying scheme based on curve fitting adaptive technique for microgrids and performs well without using any extensive communication facility. This type of relaying scheme can be used to detect faults under different microgrid modes.…”