New Infeed Correction Methods for Distance Protection in Distribution Systems

Abstract

The reliability and security of power systems may be jeopardized by the increase in the amounts of renewable generation and the uncertainties produced by these devices. In particular, the protection schemes of traditional power systems have been challenged by the integration of distributed generation (DG) resources. Distance relays (DRs), which have been mainly employed to protect transmission systems, are increasingly proposed as one of the solutions to protect distribution systems with a heavy penetration of DGs. However, conventional distance protection faces several drawbacks that might lead to maloperation. One of those challenges is the “infeed effect”, which causes the impedance seen by the distance relay to be larger than the actual positive-sequence line impedance between the fault and relay location. This paper proposes three new methods to estimate the distance to the fault in the presence of infeeds, whether in a radial distribution feeder or the transmission line. Unlike other solution methodologies in the literature that require communication links to estimate the distance to the fault, the proposed methods only need the local measurement (i.e., the voltage and current measurements at the location of the distance relay) to do the same. The performance of the method is demonstrated with a radial distribution system model in PSCAD™/EMTDC™.

Signal-based fault location method using time and frequency domain

“…Breakers are typically situated at the substation level, while smaller reclosers are positioned further along the line. Reclosers possess the capability to assess the transient nature of a fault and can safely re-close contacts if appropriate [8]. Instantaneous overcurrent relays, utilizing phasor technology, require at least one cycle to detect a fault, whereas timeovercurrent relays may take several seconds to activate.…”

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

“…Impedance or distance relays are widely employed to protect transmission networks and have recently been recommended to protect MGs, as they can detect and respond to both forward and backward faults. However, these relays face various challenges that can hinder their reliability, including issues with fault resistance, compensation factors during ground faults, and the effects of infeed currents [29,30]. In this context, DER infeed may obstruct the decision of impedance relays in MGs, as it causes the perceived impedance at the relay to be higher/lower than the actual impedance between the relay and the fault point, resulting in the relay either under-or over-reaching.…”

“…However, this adjustment may cause the relays to malfunction during disturbances, heavy loads (line loadability), system swings, etc. [29,33]. For illustration, Fig.…”

Protection Analysis of a Traveling-Wave, Machine-Learning Protection Scheme for Distributions Systems With Variable Penetration of Solar PV

“…Following these principles, existing distribution system protection consists of a highly redundant network of OC relays and fuses. Relays, which are associated with circuit breakers, disconnect the fault-affected areas from the rest of the system, and autoreclosers try to reconnect the faulted area after some time in case the fault is momentary [14]. This architecture has proved to be successful for uni-directional and radial systems.…”