Avoiding the Non-Detection Zone of Passive Loss-of-Mains (Islanding) Relays for Synchronous Generation by Using Low Bandwidth Control Loops and Controlled Reactive Power Mismatches

Abstract

This version is available at https://strathprints.strath.ac.uk/46054/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Abstract-Generation connected to electrical distribution systems requires reliable and timely detection of loss-of-mains (islanding). Passive loss-of-mains detection relays typically usemeasurements of parameters such as frequency, phase, and the magnitudes of voltage and current. If a part of the power network becomes islanded and there is a very close match between generation and demand of both active and reactive power, there is a risk that the relay will not be able to detect the loss-of-mains (LOM) event quickly, or perhaps at all. This is the "non-detection zone" or NDZ. This paper proposes a combination of 2 generator control techniques which allow the NDZ to be avoided even when the generator has significant inertia. Firstly, the natural instability (when islanded) of a grid-connected control scheme consisting of integral and droop controls is recognized and exploited. Secondly, a simple strategy is added which makes occasional small, steady-state adjustments to the reactive power output of the generator. The scheme has been tested in the laboratory and shows that the 2 second detection time required by IEEE 1547 can be achieved, even when an exact match of active power generation and demand is initially configured, and the generator has a significant inertia.

A New Load Shedding Scheme With Consideration of Distributed Energy Resources’ Active Power Ramping Capability

“…The proposed load shedding algorithm is designed for a microgrid control system as reported in [41]. As the islanding detection is not the main focus of the paper, the detailed implementation of the islanding detection for the system [41] can be found in [42]. The subsequent load shedding actions will only be triggered when an underfrequency event is detected the in the islanded mode.…”

Smart grid architecture model for control, optimization and data analytics of future power networks with more renewable energy

“…• Loss of mains (LOM) protection (Laverty, Best and Morrow, 2015;Roscoe, Burt and Bright, 2014) etc.…”

An Effective Passive Islanding Detection Algorithm for Distributed Generations

“…Capability issue of current injection method is investigated in Reference [14] and a solution to solve this problem is also introduced based on considering only certain high frequency components as injected current. Likewise, in References [15][16][17], islanding detection methods for synchronous based generators are presented. In Reference [15], two positive feedback for active and reactive power control loops are presented to make the system unstable in the islanding situation.…”

“…Afterwards, in Reference [17], new active and passive power control loops proposed to simultaneously improve the ride-through capability of the synchronous generator, as well as detecting islanding-situation. Integral controllers are added to the governor, and excitation system of the synchronous generator are added in Reference [16] to make the system marginally unstable in the islanding situation. In Reference [18], two modified active and reactive power control loops of synchronous DG is presented to make the system marginally unstable in islanding situation.…”