Table Of ContentRussian National
Committee of International Council
on Large Electric Systems
ACTUAL TRENDS
IN DEVELOPMENT OF POWER SYSTEM
PROTECTION AND AUTOMATION
Conference Proceedings
of International Scientific & Technical Conference
(Moscow, September 7–10, 2009)
Science and Engineering Information Agency
Moscow
ББК 31.27-05
УДК 621.316.925:681.5:621.311(06)
С56
С56 Actual Trends in Development of Power System Protection and Automation: Conference
Proceedings of International Scientific & Technical Conference (Moscow, September 7–10, 2009). –
Мoscow: «Science and Engineering Information Agency», 2009. – 576 p.: il.
ISBN 978-5-903564-04-0
ББК 31.27-05
УДК 621.316.925:681.5:621.311(06)
© Sushkova T.M., Smirnova L.V., Titova N.V. –
translation, 2009
© Science and Engineering Information
Agency – design, 2009
ISBN 978-5-903564-04-0
Moscow, 7–10 September 2009
CONTENTS
R. Moxley, K. Fodero, H.J. Altuve (Schweitzer Engineering Laboratories, Inc., USA)
Updated Transmission Line Protection Communications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Z. Gajić, I. Brnčić (ABB AB, SA Products, Sweden), F. Rios (Svenska Kraftnat, Sweden)
Experience with Multiterminal Line Differential Protection Installed
on Series Compensated, 400 kV Line with Five-Ends. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
T.S. Kamel, M.A. Moustafa Hassan, A. El-Morshedy (Cairo University, Egypt)
Application of Artificial Intelligent Approach in Distance Relay for
Transmission Line Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Lj.A. Kojovic, M.T. Bishop (Cooper Power Systems, USA)
Advanced Protective Relaying Based on Rogowski Coil Current Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Lj.A. Kojovic, M.T. Bishop (Cooper Power Systems, USA)
Field Experience with Differential Protection of Power Transformers
Based on Rogowski Coil Current Sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
B.M. Buchholz (NTB Technoservice, Germany), V. Henn, R. Krebs (Siemens AG, Germany),
G. Arruda (CHEFS, Germany), R. Dutra (FURNAS, Germany),
P. Campos (ELETRONORTE, Germany)
Series Compensated Lines in Bulk Power Transmission Systems
Need Special Real-Time Tested Protection Schemes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
A.V. Bulychev, G.S. Nudelman (VNIIR, Russia)
Relay Protection Precautionary Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
V.A. Efremov, Y.Y. Liamets, N.V. Podchivaline, V.S. Shevelev (Research Center Bresler, Russia)
Concepts and Solutions in 6-750 kV Line Relay Protection and Automation. . . . . . . . . . . . . . . . . . . . . . . . . . 72
S.V. Ivanov, D.V. Kerzhaev (Research Center Bresler, Russia)
Double Earth Fault Location in Isolated Networks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
M.Sh. Misrikhanov, A.L. Kulikov, A.A. Petrukhin,
D.M. Kudryavstev (FGC UES Affiliate – MES Centre, Russia)
New Algorithms of Fault Location of a Power Line 6-35 Kv
with Application of Complex Probing Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
S.L. Kuzhekov (South-Russia State Technical University, Russia), G.S. Nudelman (VNIIR, Russia)
Methods of Minimization CT Error Influence on Power System Relay
Protection Operation in Transient Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Y.Y. Liamets, D.V. Kerzhaev (Research Center Bresler, Russia),
G.S. Nudelman (VNIIR, Russia), Y.V. Romanov (Research Center Bresler, Russia)
Multidimensional Relay Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
A.N. Podshivalin, I.S. Klimatova (Research Center Bresler, Russia)
Application of Multi-dimensional Protection: Settings Calculation and Testing Methods . . . . . . . . . . . . . . 103
3
Actual Trends in Development of Power System Protection and Automation
J. Cardenas, M. Kumar (GE Digital Energy, Spain), J. Romero (RasGas, Qatar)
Problems and Solutions of Line Differential Application in Cable Transformer Protection. . . . . . . . . . . . . . 111
V.I. Nagay (South-Russia State Technical University, Russia), V.V. Nagay (Yuzhenergosetproekt,
Russia), I.V. Nagay (South-Russia State Technical University, Russia)
Adaptive Measuring Devices For Emergency Components Of Backup Protection
in Electric Distribution Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
E.M. Martinez (Comisio´n Federal de Electricidad, Mexico)
Angular Difference Protection Scheme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
M. Kezunovic, J. Ren, Ch. Pang (Texas A&M University, USA)
Improving Relay Performance by Off-line and On-line Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
M. Gubriel (University of Magdeburg, Germany), P. Komarnicki (Fraunhofer Institute
for Factory Operation and Automation Magdeburg, Germany), Z. Styczynski (University of Magdeburg,
Germany), J. Blumschein (Siemens AG, Germany), A. Phadke (Virginia Tech, USA)
Static and Dynamic Tests of Digital Measurement Devices for Power System Protection . . . . . . . . . . . . . . 146
R.A. Vainshtein (Tomsk Polytechnic University, Russia),
K.S. Lozinskiy (Siberian Chemical Plant, Russia)
Calculation Method of Short-Circuit Currents and Open-Phase Modes
Considering Electromechanical Transients. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
A.V. Zhukov, A.T. Demchuk (SO UPS, Russia), P.Ya. Kats (NIIPT, Russia),
A.V. Danilin (Altero Power, Russia)
WAMS-Based Power System Stability Margin Monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
V.K. Vanin, G.A. Evdokunin, R.N. Nikolaev, M.G. Popov (Saint-Petersburg
State Polytechnic University, Russia), A.K. Iskakov (Batis tranzit, Kazakhstan),
B.K. Ospanov, N.I. Utegulov (IPC ZHERSU, Kazakhstan)
Relay Protection and Automation System of Phase-shifting Superhigh Voltage Device . . . . . . . . . . . . . . . . 165
A.N. Doni, N.A. Doni (Research & Production Enterprise «EKRA», Russia)
Peculiarities of Longitudinal Line Differential Protection with Digital Link . . . . . . . . . . . . . . . . . . . . . . . . . 174
B. Morris, R. Moxley, Ch. Kusch (Schweitzer Engineering Laboratories, Inc., USA)
Then Versus Now: A Comparison of Total Scheme Complexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
Z. Gajic, S. Holst (ABB AB, SA Products, Sweden)
Application of Unit Protection Schemes for Auto-Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
E.F. Livgard (TNS Gallup, Norway)
Norwegian Electricity Customers’ Attitudes towards Smart Metering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210
H. Dawidczak, Th. Dufaure, H. Englert (Siemens AG, Germany)
IEC 61850 GOOSE Communication: Performance of Transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
Z. Gajić, S. Aganović (ABB AB, SA Products, Sweden), J. Benović (HEP, Croatia),
G. Leci (Koncar, Croatia), S. Gazzari (ABB, Croatia)
Using IEC 61850 Analogue GOOSE Messages
for OLTC Control of Parallel Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
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Moscow, 7–10 September 2009
D. McGinn (GE Digital Energy, Canada), M. Goraj, J. Cardenas (GE Digital Energy, Spain)
Reducing Conventional Copper Signalling in High Voltage Substations
with IEC 61850 Process Bus System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
J. Sauvé (Federal University of Campina Grande, Brazil), I. Patriota (CHESF, Brazil),
W. Porto (Federal University of Campina Grande, Brazil)
A Tool for Testing and Fault Diagnosis in IEC 61850-Based Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
U.A. Asanbaev, T.G. Gorelic, O.V. Kirienko, I.E. Kumecs (NIIPT, Russia)
Organizing Data Exchange between Relay Protection
and Automatic Emergency Control Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
S. Richards (AREVA T&D, UK), D. Chatrefou (AREVA T&D, France),
D. Tholomier (AREVA T&D, Canada), F. Gilles (AREVA T&D, France)
Non-Conventional Instrument Transformer Solutions –
Experience of the Process Bus IEC 61850-9.2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
N.G. Shulginov, A.V. Zhukov, A.T. Demchuk (SO UPS, Russia), L.A. Koshcheev,
P.Y. Kats, M.A. Edlin (NIIPT, Russia)
Concept of Emergency Control in the UES of Russia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265
B.M. Buchholz (NTB Technoservice, Germany), R. Krebs (Siemens AG, Germany),
Z. Styczynski (University of Magdeburg, Germany)
Advanced Protection and Control Solutions for Prevention of Disturbance Enlargement. . . . . . . . . . . . . . . 270
B. Cvorovic, H. Kang, P. Horton (Areva T&D, UK)
New Setting Free Out Of Step Detection and Safe Angle System Split Technique . . . . . . . . . . . . . . . . . . . . 279
D.J. Dolezilek, S. Schweitzer (Schweitzer Engineering Laboratories, Inc., USA)
Practical Applications of Smart Grid Technologies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
L.A. Koshcheev, P.Y. Kats, M.A. Edlin (NIIPT, Russia),
A.V. Zhukov, A.T. Demchuk (SO UPS, Russia)
New-Generation Technological Algorithm of Centralized AEC System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
V.V. Vasiliev, V.E. Glazyrin (Institute for Energy Systems Automation,
Novosibirsk State Technical University, Russia)
Combined Control Method for Load Shedding by Frequency and Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
N.I. Voropai, D.N. Efimov, D.B. Popov (ISEM SB RAS, Russia), K. Rehtanz,
U. Haeger (Dortmund University of Technology, Germany)
Development of Selective Automatic Systems for Prevention and Elimination
of Out-of-Step Operation Using PMU. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
А.К. Landman, А.M. Petrov, А.E. Petrov,
О.О. Sakaev (Institute for Energy Systems Automation, Russia)
Approaches to Integrated Emergency Control Systems Design Based
on Unified Computer Emergency Control Complexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319
A.V. Zhukov, A.T. Demchuk (SO UPS, Russia), P.Y. Kats, V.L. Nevelsky,
M.A. Edlin (NIIPT, Russia)
Automatic System for Asynchronous Modes Liquidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
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Actual Trends in Development of Power System Protection and Automation
N.N. Lizalek, A.N. Ladnova, M.V. Danilov (Institute for Energy Systems Automation, Russia)
Investigation into the Structure of Dynamic Stabilization Problems for Power Conjunction. . . . . . . . . . . . . 330
A.V. Zhukov (SO UPS, Russia), B.I. Mekhanoshin, V.A. Shkaptsov (OPTEN Limited, Russia)
Conductor Estate Monitoring as a Tool to Improve of Controlling Loaded Network
Infrastructure Elements under Normal and Post Emergent Operating Conditions . . . . . . . . . . . . . . . . . . . . 338
V.G. Narovliansky, D.R. Lubarsky, A.B. Vaganov (Institute «Energosetproekt», Russia),
I.A. Ivanov (EnergoIzmeritel Ltd., Russia)
ALAR-M – Microprocessor Based Device for Automation of Liquidation
of Asynchronous Regime Conditions: ABC of Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345
A.B. Osak, A.V. Domyshev, E.Y. Buzina (ISEM SB RAS, Russia)
Modern Approaches to Developing Hardware and Software System
for Operation and Emergency Control of Large-Scale Power Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351
D.A. Panasetsky, N.I. Voropai (ISEM SB RAS, Russia)
Multi-Agent Approach to Coordination of Different Emergency Control
Devices against Voltage Collapse. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 358
V.A. Andreyuk, T.A. Gushina (NIIPT, Russia), A.V. Zhukov, A.T. Demchuk (SO UPS, Russia)
Estimating the Efficiency of Transient Control Algorithms at the 500 kV Surgutskaya TP –
Tumen Substation – Reftinskaya TP Transmission System on Basis of WAMS Data. . . . . . . . . . . . . . . . . . 366
H. Kang, B. Cvorovic, C. Mycock (Areva T&D, UK)
PMU Simulation and Application for Power System Stability Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . 374
H.-J. Herrmann (Siemens AG, Germany)
System Fault Analysis by means of Recordings from Protection Devices
and Disturbance Recorders – Today and in the Future. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382
M. Wache (Siemens AG, Germany)
Wide Area Monitoring with Phasor Measurement Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391
V.A. Shuin, А.S. Lifshits, О.А. Sarbeeva,
Е.S. Chugrova (Ivanovo State Power University, Russia)
Analysis of Current Protection Functioning Dynamic Conditions
from Ground Faults in Average Voltage Networks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399
S.G. Arzhannikov, A.S. Vtorushin, E.Yu. Ivakhnenko, O.V. Zakharkin (Institute for Energy
Systems Automation, Russia), D.S. Lotsman (SO UPS Affiliate – Siberia IDO, Russia)
Hierarchical Emergency Control System of the UES of Siberia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408
O.S. Borodin, P.A. Kopylov, Y.V. Ivanov,
A.E. Lesnov, K.I. Aprosin (Prosoft-Systems, Russia)
Emergency automation of power systems, modern engineering solutions.
Standard IEC 61850 and its influence on relay protection
and emergency automation functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 415
J. Cardenas (GE Digital Energy, Spain)
Evaluation of the Ground Operating Current in Industrial Systems
with Network Distribution through MV Cables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 420
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Moscow, 7–10 September 2009
J. Cardenas (GE Digital Energy, Spain), S. Cox, P. van Wyk (Powertech IST Energy,
South Africa), B. Chaka, M. Msimango, M. Klimek, A. Perera (Eskom, South Africa)
New Approach in Functionality and Testing for HV Capacitor Bank Protection . . . . . . . . . . . . . . . . . . . . . . 429
J. Cardenas, A. Lopez de Viсaspre (GE Digital Energy, Spain),
C. McTaggart (Scottish Power, UK), A. Bone (GSS, UK)
Improvements in Power System Integrity Protection Schemes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 441
V.A. Efremov, I.S. Klimatova (Research Center Bresler, Russia), V.M. Kozlov (FGC UES, Russia)
Methods development and settings calculation automation of RDA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452
V.A. Efremov, N.V. Podchivalin (Research Center Bresler, Russia), G.S. Nudelman (VNIIR, Russia)
Application of Complex Absolute Selective Protection on 220-750 kV Lines. . . . . . . . . . . . . . . . . . . . . . . . . 458
V.A. Efremov, Y.V. Romanov (Research Center Bresler, Russia)
Line Phase Comparison Protection Improvement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 466
Z. Gajić (ABB AB, SA Products, Sweden), A. Bonetti (Megger Sweden AB, Sweden)
Easy Method for Testing Transformer Differential Relays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471
Z. Gajić, S. Holst (ABB AB, SA Products, Sweden), D. Bonmann (ABB AG, Transformers,
Germany), D. Baars (ELEQ bv, Netherlands)
Stray Flux and Its Influence on Relay Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483
J. Hauschild (Vattenfall Europe, Germany), L. Philippot (NetCeler, France),
G. Fleischer (Siemens AG, Germany)
WEB-based Automatic Arc Classification for Single Phase Faults
Based on Systematic Fault Record Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 492
M.J. Kletcel, A.S. Stinskiy (Pavlodar State University after Toraigyrov, Kazakhstan)
Algorithms for Increasing Reserve Protection Transformers’ Sensitivity towards
Distant Diphase Short Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 499
A.V. Korotkov (EFR Telecom, Russia), A.V. Maiorov (MOESK, Russia),
D.V. Sulimov (PARMA, Russia)
System of Selective Telecontrol of Electric Energy Electroreceivers
on Radio Channels Communication (SAUN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504
N.N. Kurguzov, L.I. Kurguzova (Pavlodar State University after Toraigyrov, Kazakhstan)
About Increasing the Technical Perfection of the Powerful Electric Motors’ Differential Protection. . . . . . 510
M.Sh. Misrikhanov, A.L. Kulikov, D.M. Kudryavstev,
A.A. Petrukhin (FGC UES Affiliate – MES Centre, Russia)
Instrument solutions of automatic fault location finder of power line on the basis of active probing . . . . . . . 517
A.V. Mokeev (Arkhangelsk State Technical University, Russia)
Intellectual Electronic Devices Design for Electric Power Systems
Based on Phasor Measurement Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
V.I. Nagay, S.V. Sarry, А.V. Lukonin (South-Russia State Technical University, Russia)
Quick-Response Relay Protections for High-Voltage Electric Equipment of Metal-Clad
Type with Sensors for Electric and Non-Electric Values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 531
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Actual Trends in Development of Power System Protection and Automation
V.V. Platonov, A.S. Zasypkin, S.L. Kuzhekov (South-Russia State Technical University, Russia)
To 100th Anniversary of Alexander Dmitrievitch Drozdov, the Professor . . . . . . . . . . . . . . . . . . . . . . . . . . . 538
N.A. Selezneva (Institute «ENERGOSETPROJECT», Russia)
Line Overload Limitation Automation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 543
A.V. Shmoilov (Tomsk Polytechnic University, Russia)
Algorithms of setting-up and principles of construction of relay protection . . . . . . . . . . . . . . . . . . . . . . . . . . 552
V.A. Shuin, E.S. Chugrova (Ivanovo State Power University, Russia)
Analysis of 100% Ground Fault Protection Performance under Arc Discrete Faults
in a Fixed Coil Winding of the Generator Operating in the Unit with a Transformer. . . . . . . . . . . . . . . . . . . 560
I.S. Solonina (ABB Automation LLC, Russia)
Introduction into Information Analysis of Mass Produced (Standard) ABB Terminals. . . . . . . . . . . . . . . . . 565
V.K. Vanin, G.A. Evdokunin, R.N. Nikolaev, M.G. Popov (Saint-Petersburg State Polytechnic
University, Russia), A.V. Mokeev (Arkhangelsk State Technical University, Russia)
Accuracy Increase Methods of Microprocessor-based Relay Protection and Automation . . . . . . . . . . . . . . 570
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Moscow, 7–10 September 2009
Updated Transmission Line Protection Communications
ROY MOXLEY, KEN FODERO, AND HECTOR J. ALTUVE
Schweitzer Engineering Laboratories, Inc.
Abstract — the telecommunications revolution has increased the options and capabilities available for
communications-based protection of transmission lines. To improve tripping speeds on long and short lines,
protection engineers can select from a host of media, protocols, and logic schemes. The question to address is
what communications scheme is best for which circumstances.
This paper begins by establishing performance baselines of protection scheme operating times measured
in event reports for a variety of in-service lines. It includes various successful systems and takes into account
all of the elements that must be addressed when engineering a protection scheme, such as relay pickup time,
communications interface and latency, coordinating time delays, and sequential tripping times.
These in-service schemes are compared with laboratory tests of new systems, using radio and fiber-optic
communications with serial and Ethernet protocols. Methods of optimizing different systems are tested and
evaluated; the final results are tabulated and compared.
No single scheme is best for all circumstances. With comparison data, the protection engineer can select the
best options to improve the overall power system performance. Recognizing the strengths and weaknesses of
different schemes assists the engineer in addressing new situations. Comparing laboratory tests and in-service
performance provides a tool for evaluating a transition to new technologies.
1. INTRODUCTION
Communications-based transmission line protection schemes have been in service for well over half a
century [1]. Early communications systems used copper conductors and included privately owned pilot wire
channels, dedicated telephone circuits, and power line carrier channels. In the early 1970s, utility-owned mi-
crowave links began to replace copper wires in transmission systems, and licensed radio transceivers extended
supervisory control and data acquisition (SCADA) reach into medium-voltage distribution circuits. Protection
schemes were designed to accommodate the weaknesses and strengths of the communications medium in order
to reduce overall tripping times and improve system security.
Optical fiber and radio are two relatively new communications systems available today. When selecting a
protection scheme, compare different types of these systems. The scheme selection must address the reliability
of transmitting a signal to the remote end during a fault and preventing a false transmission during a fault.
Selecting a protection scheme and communications type has been further complicated by the use of ad-
vanced protocols to send fault information between the line terminals. In addition to contact closures, serial
and Ethernet protocol options are now available for data transmission. The impact of protocol overhead, er-
ror detection and correction, addressability, and other factors must be included in the process of selecting a
communications-based protection scheme.
This paper only addresses two-terminal lines. Many of the principles discussed here apply to multiterminal
lines but should be addressed in a separate paper due to the added complexity. While many of the elements of
Fig.1 are not included in every scheme, it will be used as a general case throughout this paper.
Fig. 1: General transmission line protection with communications
9
