Contents lists available at ScienceDirect Electric Power Systems Research journal homepage: www.elsevier.com/locate/epsr Tuning interconnection relays using a multi-agent system to detect weak infeed conditions J. Treviño a , A. Conde b, ⁎ , E. Fernández b , O. Arreola a a Technological Institute of Nuevo León, Nuevo Leon, Mexico, Mexico b Faculty of Mechanical and Electrical Engineering, Autonomous University of Nuevo Leon, Nuevo Leon, Mexico ARTICLE INFO Keywords: Multi-agent systems Interconnection Relays Non-regulated sources Weak infeed ABSTRACT In this paper, a multi-agent system (MAS) is used to enhance the performance of protection under dynamic operating conditions that result in a weak source contribution. A traditional relay setting that is established for the worst-case scenario is not suitable for systems with a wide operating range, mainly due to the presence of non-regulated sources. A MAS is proposed that operates on-line to modify relay settings in response to topo- logical changes due to the output of lines, loads or generation, and identifies low contributions from sources. The gang architecture for the relay coordination is simulated in Matlab/Simulink and controlled using Jade. Matlab enables modeling that integrates the diverse dynamics of the elements of the electrical network, and Jade allows for a multi-agent environment that facilitates the different actions that are activated in the network. The MAS architecture improves the relay performance under fault conditions by detecting weak infeed conditions caused by both non-regulated sources and low-level conventional sources. The on-line coordination between inter- connection relays and line relays uses the MAS architecture to send transfer trips, and uses non-conventional time curves to improve the operation times. The results show that the MAS improves the sensitivity and op- eration times of the interconnection relays. 1. Introduction Since the early 1990s, numerous changes have occurred in the power generation environment. Factors such as the conservation of natural resources, growing environmental concerns and the rising costs of fossil-based energy have prompted the development of more efficient generation and distribution methods [1]. A study by the Electric Power Research Institute (EPRI) indicates that 25% of new power generation will be in a distributed form in future years, and a study by the Natural Gas Foundation finds that this could be as high as 30% [2]. The com- mission for examine the feasibility of EU CO 2 reduction through re- newable energy, found that 60% of these energy sources may be de- centralized [3]. The integration of these non-regulated sources must continue to allow the delivered energy to be reliable and of sufficient quality that the network can continue to operate under acceptable conditions [4,5]. The presence of non-regulated sources such as distributed genera- tion (DG) and fault limiters modifies the fault currents of the system, and these elements must be considered in relay coordination. In Ref. [5], it is mentioned that there is always a probability that the relays may fail. The use of batteries and flywheels also affects the criteria of operation of the electricity network [6,7]. Control of the sub-trans- mission and distribution systems has therefore been shaped by a high tendency towards distributed schemes, and several different elements of the network must be considered in the study of power flows, faults and relay coordination [8]. The trend towards the use of tools for the analysis of such systems should include the integration of the various elements of the network. The operational analysis of overcurrent relays is complex compared to the other protection principles; the time for which the protection should operate is not known, as it depends on the evolution of the fault current. The relay setting is therefore established by defining the maximum boundary condition both for the steady state, to determine the pickup current of relays, and for the dynamic state, to perform protection coordination. The intermittent nature of the sources causes the operating range of the electrical networks to be wider, meaning that the implementation of protection for any other operating conditions may cause a degradation in performance. Furthermore, under weak infeed conditions, the interconnection relay located at the point of in- terconnection may be insensitive, or may not coordinate with system https://doi.org/10.1016/j.epsr.2019.01.002 Received 16 October 2018; Received in revised form 21 December 2018; Accepted 3 January 2019 ⁎ Corresponding author. E-mail addresses: jtrevm2009@yahoo.com.mx (J. Treviño), arturo.condeenr@uanl.edu.mx (A. Conde), kikafh@gmail.com (E. Fernández), oarreola_soria@yahoo.com.mx (O. Arreola). Electric Power Systems Research 169 (2019) 139–149 0378-7796/ © 2019 Elsevier B.V. All rights reserved. T