Coordination of non‐directional overcurrent relays and fuses in active distribution networks considering reverse short‐circuit currents of DGs

Abstract

The main protection equipment in radial distribution networks are non-directional overcurrent relays (NDOCR) and fuses which are coordinated using the conventional protection coordination method. By installing distributed generations (DGs) in the network, reverse short-circuit currents (SCC), injected from DGs, can lead to false tripping of NDOCRs and false melting of fuses. In the previous studies, some methods have been proposed to overcome these issues using directional overcurrent relays, fault current limiter, and adaptive methods that relay on communication. The present paper proposes a new coordination method to prevent these issues without the need for installing a new equipment, by proposing a new set of selectivity constraints. Here, selectivity between equipment is established, and false tripping and false melting issues are mitigated. The coordination of protection equipment according to the proposed method requires the use of optimization algorithms, and therefore, the proposed method is formulated as a mixed-integer linear programming method to take advantage of mathematical optimization algorithms. The proposed coordination method is applied to a real distribution network and the results indicate the high efficiency of the proposed method in dealing with false relay tripping and fuse melting issues.

Optimal Protection Coordination of Active Distribution Networks Using Smart Selection of Short Circuit Voltage-Based Relay Characteristics

“…In (2), the minimum allowed pickup current setting of DOCRs has been mathematically expressed. In some references, the time multiplier settings (TMSs) are not optimized, and they would be selected according to pre-defined values equal to (2). However, in this study to improve the speed of the protection system and facilitate the coordination constraint meeting, the current settings are also optimized.…”

“…The protection of distribution systems is one of the most important issues in microgrids (MGs), active distribution networks (ADNs), and smart grids (SGs) in the presence of distributed generations (DGs) [1,2]. The advantages of DGs and distributed energy resources (DERs), e.g., the reduction of energy losses, improvement of voltage, and increase of overall energy efficiency, lead to increasing deployment of these energy sources.…”

Relay protection sensitivity integrated optimal placement and capacity of inverter interfaced distributed generators in distribution networks

“…The DG connection into the distribution network (DN) can reduce the carbon emission, diminish the fuel consumption, lower power transmission loss, elevate the voltage profile to improve the power quality, and enhance the power system reliability and security [ 3 , 4 ]. Nonetheless, the DG connection alters the power flow and fault analysis [ 5 , 6 ], challenging the DN planning strategies.…”

Optimal adaptive protection of smart grids using high‐set relays and smart selection of relay tripping characteristics considering different network configurations and operation modes

“…However, complications have been imposed on the SGs and MGs’ control and protection systems due to the integration of DGs into the conventional structure of distribution networks [7, 8]. Hence, several studies in the literature have been devoted to optimizing the protection system of SGs and MGs [9, 10]. The topological evolution of power distribution networks comprising DG units and the islanding capacity of MGs have led to significant changes in the magnitudes of short‐circuit currents, consequently affecting the reliability of protection systems in terms of loss of selectivity, sensitivity, and dynamic response [11, 12].…”