Modelling and analysis of asymmetrical latency in packet-based networks for current differential protection application

Steven M. Blair, Campbell D. Booth, Bram De Valck, Dominique Verhulst, Kin-Yee Wong

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Current differential protection typically requires symmetrical communications channels—with equal latency in each direction—for correct operation. Conventionally, this has been delivered using protocols such as IEEE C37.94 over a Time-Division Multiplexing (TDM) wide-area network (WAN). Modern packet-based WANs offer improvements in efficiency, flexibility, and cost-effectiveness for utility applications. However, jitter is unavoidable in packet-based networks and, in extreme cases, jitter inevitably results in substantial asymmetrical latency in communications paths. This paper clearly defines how a new source of asymmetry arises due to the use of "de-jitter" buffers, which can jeopardize critical protection services. This is demonstrated using an analytical modelling approach, which precisely quantifies the degree of risk, and through real-time demonstration with actual devices, involving current differential protection over an IP/MPLS WAN. Using a novel method of real-time manipulation of Ethernet traffic to emulate large WANs, the modelling approach has been validated. It is shown how the sensitivity of relays to asymmetry depends on the protection settings and the magnitude of the measured load current. To address the risk of protection maloperation, a new approach for compensating for asymmetrical latency has been comprehensively validated. These developments will be of immediate interest to utilities operating, or migrating to, a packet-based infrastructure.
LanguageEnglish
Pages1-8
Number of pages8
JournalIEEE Transactions on Power Delivery
Early online date11 Aug 2017
DOIs
Publication statusE-pub ahead of print - 11 Aug 2017

Fingerprint

Wide area networks
Jitter
Time division multiplexing
Cost effectiveness
Ethernet
Demonstrations
Network protocols
Communication

Keywords

  • communications
  • current differential protection
  • IEEE C37.94
  • IP/MPLS
  • power system protection
  • teleprotection
  • time synchronization
  • wide-area networks

Cite this

@article{515bf5d2657a49a18f8149e1cc10c301,
title = "Modelling and analysis of asymmetrical latency in packet-based networks for current differential protection application",
abstract = "Current differential protection typically requires symmetrical communications channels—with equal latency in each direction—for correct operation. Conventionally, this has been delivered using protocols such as IEEE C37.94 over a Time-Division Multiplexing (TDM) wide-area network (WAN). Modern packet-based WANs offer improvements in efficiency, flexibility, and cost-effectiveness for utility applications. However, jitter is unavoidable in packet-based networks and, in extreme cases, jitter inevitably results in substantial asymmetrical latency in communications paths. This paper clearly defines how a new source of asymmetry arises due to the use of {"}de-jitter{"} buffers, which can jeopardize critical protection services. This is demonstrated using an analytical modelling approach, which precisely quantifies the degree of risk, and through real-time demonstration with actual devices, involving current differential protection over an IP/MPLS WAN. Using a novel method of real-time manipulation of Ethernet traffic to emulate large WANs, the modelling approach has been validated. It is shown how the sensitivity of relays to asymmetry depends on the protection settings and the magnitude of the measured load current. To address the risk of protection maloperation, a new approach for compensating for asymmetrical latency has been comprehensively validated. These developments will be of immediate interest to utilities operating, or migrating to, a packet-based infrastructure.",
keywords = "communications, current differential protection, IEEE C37.94, IP/MPLS, power system protection, teleprotection, time synchronization, wide-area networks",
author = "Blair, {Steven M.} and Booth, {Campbell D.} and {De Valck}, Bram and Dominique Verhulst and Kin-Yee Wong",
note = "{\circledC} 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.",
year = "2017",
month = "8",
day = "11",
doi = "10.1109/TPWRD.2017.2738921",
language = "English",
pages = "1--8",
journal = "IEEE Transactions on Power Delivery",
issn = "0885-8977",

}

Modelling and analysis of asymmetrical latency in packet-based networks for current differential protection application. / Blair, Steven M.; Booth, Campbell D.; De Valck, Bram; Verhulst, Dominique; Wong, Kin-Yee.

In: IEEE Transactions on Power Delivery, 11.08.2017, p. 1-8.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Modelling and analysis of asymmetrical latency in packet-based networks for current differential protection application

AU - Blair, Steven M.

AU - Booth, Campbell D.

AU - De Valck, Bram

AU - Verhulst, Dominique

AU - Wong, Kin-Yee

N1 - © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

PY - 2017/8/11

Y1 - 2017/8/11

N2 - Current differential protection typically requires symmetrical communications channels—with equal latency in each direction—for correct operation. Conventionally, this has been delivered using protocols such as IEEE C37.94 over a Time-Division Multiplexing (TDM) wide-area network (WAN). Modern packet-based WANs offer improvements in efficiency, flexibility, and cost-effectiveness for utility applications. However, jitter is unavoidable in packet-based networks and, in extreme cases, jitter inevitably results in substantial asymmetrical latency in communications paths. This paper clearly defines how a new source of asymmetry arises due to the use of "de-jitter" buffers, which can jeopardize critical protection services. This is demonstrated using an analytical modelling approach, which precisely quantifies the degree of risk, and through real-time demonstration with actual devices, involving current differential protection over an IP/MPLS WAN. Using a novel method of real-time manipulation of Ethernet traffic to emulate large WANs, the modelling approach has been validated. It is shown how the sensitivity of relays to asymmetry depends on the protection settings and the magnitude of the measured load current. To address the risk of protection maloperation, a new approach for compensating for asymmetrical latency has been comprehensively validated. These developments will be of immediate interest to utilities operating, or migrating to, a packet-based infrastructure.

AB - Current differential protection typically requires symmetrical communications channels—with equal latency in each direction—for correct operation. Conventionally, this has been delivered using protocols such as IEEE C37.94 over a Time-Division Multiplexing (TDM) wide-area network (WAN). Modern packet-based WANs offer improvements in efficiency, flexibility, and cost-effectiveness for utility applications. However, jitter is unavoidable in packet-based networks and, in extreme cases, jitter inevitably results in substantial asymmetrical latency in communications paths. This paper clearly defines how a new source of asymmetry arises due to the use of "de-jitter" buffers, which can jeopardize critical protection services. This is demonstrated using an analytical modelling approach, which precisely quantifies the degree of risk, and through real-time demonstration with actual devices, involving current differential protection over an IP/MPLS WAN. Using a novel method of real-time manipulation of Ethernet traffic to emulate large WANs, the modelling approach has been validated. It is shown how the sensitivity of relays to asymmetry depends on the protection settings and the magnitude of the measured load current. To address the risk of protection maloperation, a new approach for compensating for asymmetrical latency has been comprehensively validated. These developments will be of immediate interest to utilities operating, or migrating to, a packet-based infrastructure.

KW - communications

KW - current differential protection

KW - IEEE C37.94

KW - IP/MPLS

KW - power system protection

KW - teleprotection

KW - time synchronization

KW - wide-area networks

UR - http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=61

U2 - 10.1109/TPWRD.2017.2738921

DO - 10.1109/TPWRD.2017.2738921

M3 - Article

SP - 1

EP - 8

JO - IEEE Transactions on Power Delivery

T2 - IEEE Transactions on Power Delivery

JF - IEEE Transactions on Power Delivery

SN - 0885-8977

ER -