Electric Energy T&D - Index

Electric Energy T&D - EEMag March / April 2008 - Index

william Tyler morgan
Network Engineer II
EPB Chattanooga, TN
Providing High Speed Relay Fault Protection
between Substations
By
Abstract:
Serial communications has been the mainstay
for communication systems for more than
a decade using RS 3 and RS485 as the
physical layer. However, the Ethernet juggernaut
is enticing systems engineers to re-evaluate
their existing approach to telemetry with the
potential benefits of a bigger ‘pipe’. Fortunately,
familiar protocols support TCP/IP over Ethernet
making the switch relatively easy for greenfield
deployments. Retrofitting Ethernet and newer
IEDs into existing communications systems
require supporting a hybrid network of both
Ethernet and serial devices. One approach to
a hybrid network is serial tunnelling through
serial servers as described below and includes
an example illustrating the benefits of a real
implementation.
Ethernet Brief History
Today Ethernet is the predominant and
most popular networking technology used in
office and home environments. Their use is
quickly becoming popular for industrial and
utility applications including substation
automation networks.
Ethernet networks were not developed with the
intention of being used in substations and other
harsh environments. New Ethernet equipment
has been designed to operate under extreme
Jason lee Read
Senior Engineer
EPB Chattanooga, TN
harsh environment; therefore, both industrial
and utility networking experts are moving
forward accepting the limitations of Ethernet
networks and solving the associated problems,
with the sole objective of taking advantage of
the benefits provided by Ethernet.
Ethernet in Substation
Environment
If Ethernet devices are used in substation
automation applications, they should
comply with either IEC 61850-3 or IEEE
P1613 standards for EMI immunity and
environmental requirements to ensure
reliable operation of networking equipment
in substation environments.
For applications where the Ethernet network
will be involved in critical protection functions,
the Ethernet switches should comply with the
class 2 device definition given in IEEE P1613
(i.e. error free communications during the
application EMI immunity type tests).
Managed Ethernet switches with advanced Layer
and Layer 3 features such as IEEE 80 .3
Full-Duplex operation (no collisions), IEEE
80 .1p Priority Queuing, IEEE 80 .1Q VLAN,
IEEE 80 .1w Rapid Spanning Tree and IGMP
Snooping / Multicast Filtering should be used to
ensure real-time deterministic performance.
68 I March-April 2008 Issue
René midence
Utility Market Manager
RuggedCom Inc.
A variety of flexible network architectures
offering different levels of performance,
cost and redundancy are achievable using
managed Ethernet switches.
The following are a few reasons why migrating
to Ethernet is the way of the future in
Substation Automation:
• Enables Peer-to-Peer Communications
• Allow for Multiple Masters
• Client – Server vs. Master – Slave
• Higher data transfer
• Higher bandwidth
• Fast Network Recovery protocols
Enabling Peer-to-Peer
Communications
Peer-to-peer communication allows two
or more protection and control relays to
share information, enabling the potential
for extremely fast system reconfiguration,
enhanced protection and improved reliability.
Typical applications being deployed include
protection pilot schemes, relay cross-tripping,
distributed source transfer schemes and bus
differential protection.
As previously noted, Ethernet as a media
has been mentioned a number of times and
installing Ethernet-based LANs in substations
is a growing trend.