A New Method for Optimal Coordination of Overcurrent Relays Considering the Communication Channels Constraints

Abstract

<p>The most of the new protective schemes are based on a communication channel, which cannot be guaranteed in practice. However, during blackouts or cascading failures in the power grid, as system conditions change significantly and rapidly, more information exchanges may be required by the control centers and substations. In other words, the communication channels are operating with high load and therefore become more vulnerable when the power grid is in contingent conditions. Thus, relying on the communication channel for decision making may not be the optimal solution for protective relays, although it might be beneficial to have information exchange. In this article, a novel protective logic is proposed based on phasor measurement units (PMUs) data for optimal coordination of overcurrent relays. PMUs measure the positive sequence voltage at two substations separated by hundreds of miles which are synchronized precisely with the aid of a GPS satellite system. The precise time-tags are attached with samples, and this information is exchanged over communication channels and collected by control centers and/or substations. By extracting the relevant information from these measurements, phasor information can be obtained at any node where PMUs are installed in the power grid. This can be used to do more accurate state estimation, control, and protection. In these relays, besides current and voltage, phasor information has become an important measurement in decision making. The proposed method is tested on IEEE 8-bus standard network.</p>

Protection coordination of directional over current relay with distributed generation

“…where n is the number of relays, tij is operating time of i th relay for fault in j th zone. The constraints to solve this optimization problem are divided in three sections [6], [7], [9], [10].…”

“…For this reason, the coordination of protection scheme plays a foremost part in the power scheme to protect the electrical component on or after fault current [5]. Normally, protection has been done using the coordination of relying arrangements which is depends upon the analysis of short circuit and load flow [6]. In relay kind of coordination protection, the overcurrent (OC) relay process is extensively utilized.…”

A review of adaptive overcurrent protection in distribution networks with integration of distributed energy resources

“…The miscoordination between two adjacent feeders can occur when DER are introduced in the distribution networks. Losing the protection coordination may cause the substantial problem in power system reliability and outage of large number of distribution feeder [42]. The traditional coordination of protection system are designed in radial systems is based on time current curves (TCC).…”