IEEE PES T&D Conference & Exposition 2022 - 131

IW
Merging
Unit
L
R
IR
Unicast
Over
Fiber-Optic
Cable
IX
Merging
Unit
Relay 1
IL
IR
For Further Reading
T. Takagi, Y. Yamakoshi, M. Yamaura,
R. Kondow, and T. Matsushima,
" Development of a New Type
Fault Locator Using the One-terminal
Voltage and Current Data, "
IEEE Transactions on Power Apparatus
Systems, Vol. PAS-101, August
1982.
E.O. Schweitzer, A. Guzman,
Relay 2
figure 11. Differential scheme implemented using merging units at Terminal L and a
conventional relay at Terminal R.
87L scheme that uses point-to-point DSS devices at Terminal
L and a conventional relay at Terminal R. The data acquisition
process is transparent to the differential element with the characteristic
previously described. That is, the two terminals of an
87L scheme can have different data acquisition techniques.
Summary
Line current differential techniques provide reliable protection
in grids with high and/or variable penetration of inverterbased
resources. They are not affected by low levels of fault
current or unpredictable voltages associated with inverters.
Modern line current differential protective relays take
advantage of the current information from all-line terminals
to provide accurate multiterminal impedance-based fault
locating. The most advanced line current differential relays
exchange traveling wave time stamps to provide one-towerspan
fault-locating accuracy.
Line differential schemes can be implemented using a
wide variety of communication and integration techniques.
These techniques include dedicated fiber-optic networks
using time-domain multiplexing, packet switching, or wavelength-division
multiplexing. Within the substation, the line
differential relays can gather voltage and current data in realtime
using point-to-point or network-based architectures. Pointto-point
architectures have the advantage of simplicity, and network-based
architectures have the advantage of data sharing.
Line current differential schemes can be implemented using
M. Mynam, V. Skendzic, and B.
Kasztenny, " Locating Faults by the
Traveling Waves They Launch, "
40th Annual Western Protective
Relay Conference, October 2003.
J. Roberts, D. Tziouvaras, G.
Benmouyal, and H. Altuve, " The
Effect of Multiprinciple Line Protection on Dependability
and Security, " 54th Annual Georgia Tech Protective Relaying
Conference, May 2001.
P. Robertson, K. Fodero and C. Gray, " Solving the Inherent
Problem of Transporting Serial Teleprotection Circuits
over MPLS, " CIGRE Study Committee B5 Colloquium,
Tromso, Norway, June 24-28, 2019.
IEC 61850-9-2 International Standard, Communications
Networks and Systems for Power Utility Automation-Part
9-2: Specific Communication Service Mapping
(SCSM)-Sampled Values over ISO/IEC 8802-3. 2011.
IEEE C37.94-2017-IEEE Standard for N times 64 kbps
Optical Fiber Interfaces between Teleprotection and Multiplexer
Equipment.
IEEE 1588-2019-IEEE Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and
Control Systems.
Biographies
Scott Manson is with Schweitzer Engineering Laboratories,
Inc., United States.
Fernando Calero is with Schweitzer Engineering Laboratories,
Inc., United States.
Armando Guzman is with Schweitzer Engineering Laboratories,
Inc., United States.
p&e
relays with different data acquisition
technologies. For example,
traditionally connected terminals in
an 87L scheme can be mixed with
terminals that are part of digital
secondary systems.
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