This paper describes the application
of the modern automation
platform in electrical transmission
substations. The applications described
within are not “bleeding edge” or merely
theoretical. Working, proven examples
of everything described in this paper can
be found in at least one U.S. or Canadian
substation, but few substations include all
platform applications.

The modern automation platform
consolidates solutions previously implemented
in multiple physical boxes from
different suppliers. A single automation
platform can perform the roles of security
gateway, SCADA RTU, communication
processor, port switch, protocol
converter, sequence of events recorder,
alarm annunciator and substation HMI.

Economic, technological and cyber
security forces have driven this functional
consolidation. Figure 1 depicts the
many components of a traditional transmission
substation automation system,
while Figure 2 illustrates the configuration
of the modern automation platform.
Having fewer boxes reduces hardware,
purchasing, installation and maintenance
costs, while having a single configuration
tool reduces training and configuration
costs. Thanks to technological advances,
powerful yet inexpensive processors can
now perform complex data processing
and display tasks in the tough substation
environment without a fan, hard drive
or other moving parts. Modern software
development tools and operating systems
are also ideally suited for the embedded,
real-time environment. Therefore, technology
is no longer a barrier to entry for
niche vendors.

Finally, since substation security functions
are easier to manage through a
single gateway, the centralized topography
enabled by the automation platform
allows a simpler and more secure
approach to cyber security.
Each of the roles of the modern automation
processor is described below:

Security Gateway

The specialized security functions
required in transmission substations
include:

• Firewalls;
• Data encryption and VPNs;
• Local and centralized authentication;
  and
• Event and alarm logging.

Secure physical routers/switches from
traditional IT suppliers and security
software running on PCs have traditionally
provided a solution. However,
transmission substation engineers prefer
not to purchase and maintain separate
IT-oriented boxes, some of which may
not meet all substation environmental
specifications and may require specialized
and extensive training. To resolve
this situation, the automation platform
has taken on these security functions as
resident tasks, with functions optimized
and simplified for substation automation
applications.

Traditional SCADA RTU Functions

The traditional substation remote terminal
unit (RTU) has performed its task
reliably in transmission substations since
the advent of computers, reporting realtime
data to one or more Masters and
executing control commands. The challenge
has been to get the RTU to do more
than it was designed to do. Increasingly,
users need to obtain SCADA data from
IEDs using IED protocols, some of which
are proprietary and require specialized
knowledge to emulate. Users also need to
move data securely from the RTU to nontraditional
users. The modern automation
platform performs all of the traditional
RTU tasks plus these new tasks in a single
package.

Communications Processing

Communications processing includes the
tasks of protocol conversion and media
conversion. These have often been handled
by specialized and separately powered
hardware boxes. Examples include
separate bit-to-byte converters, legacy
protocol to DNP3.0 converters, RS232-to-
RS485 and serial-to-fiber converters and
Ethernet-to-serial converters. However,
all of these options increase cost, complicate
automation system design and
reduce system reliability.

Alternately, the modern automation
platform performs these functions with a
modular software and hardware architecture
that permits any Master or Slave protocol
to be configured on any combination
of built-in bit synchronous, RS232, RS485,
fiber optic or Ethernet ports. The resulting
design is cleaner, more affordable and
more reliable.

The modern automation platform also
enables data to be routed in nonconventional
ways, such as Master-Master (using
the automation platform as a mailbox)
and Slave-Slave (reading data from one
Slave and writing these data to a second
Slave).

Distributed I/O With Accurate Time

Most traditional RTUs have required
all substation inputs and outputs to be
wired back to a centralized location,
particularly if the inputs needed to be
time-stamped to an accuracy of one millisecond.
Today high-performance distributed
I/O modules with IRIG-B timecode
formats can be mounted on substation
breakers and transformers, with a
single fiber optic connection routed back
to the substation RTU or automation platform.
Some distributed I/O designs can
also synchronize I/O module time with
IRIG-B being transmitted over the serial
connection to the module, or using NTP
over Ethernet, to further reduce IRIG-B
wiring costs.

Accurate Time Management

Accurate time-formatting (such as IRIGB)
and accurate time-stamping of events
have been part of transmission substan
tion automation design for at least 15
to 20 years. But there has been little
coordinated and integrated management
of time stamps from multiple IEDs in
multiple protocols and to multiple Masters.
For example, time-stamped events
in proprietary relay protocols need to
be transmitted to the SCADA Master in
the SCADA protocol, typically as DNP3.0
events with time. In addition, IEDs that
communicate using protocols that do not
support time need to have a time stamp
placed on events as they are received.
Multiple SCADA Masters and HMIs may
each require the same events with time
but possibly in a different protocol. The
modern automation platform handles
these time management functions as
standard routines.

Local Logic Processing and Control

Local logic processing and control for
schemes such as breaker-and-one-half,
synchro-check, breaker failure, underfrequency
load shed and black start have
traditionally been implemented in protective
relays and dedicated programmable
controllers. While this is still the case, the
trend is toward less logic implemented in
programmable logic controllers and more
in the automation platform. The math
and logic packages available in the automation
platform are based upon open
and well-supported tools such as Visual
Basic and IEC 61131. Many logic tasks
that require data from different parts of
the substation are handled easily by the
automation platform, as it is the central
repository for all substation data.

Protective Relay Record Management

Traditionally it has been common to apply
a separate communication processor or
port switch to provide access to engineering
data residing in substation protective
relays. The tools to access and process
records have also traditionally resided
on remote PCs. Today the automation
platform serves as a pass-through port
switch, supporting dial-in connections
as well as local and remote Ethernet
connections. The automation platform
can also filter and preprocess relay fault
records, so that only pertinent records
are retrieved for analysis (for example,
filter-based upon fault distance) or to
simplify analysis (for example, pulling
apart separate relay events from one
large flat “file” and integrating with
record viewer packages).

Substation HMI

Substation engineers have always desired
local tabular or graphic visualization of
real-time operating conditions in the
more critical transmission substations.
The challenge has been to justify the
relatively high cost of buying the HMI
software, configuring the displays and
maintaining the PC-based hardware
platform and operating system. Users
report that the highest single cost in
substation automation is the PC-based
HMI. Some of the PC hardware issues
have been addressed with the advent of
rugged PC power supplies and solid-state
hard drives, but other costs remain. The
modern automation platform can serve
up standard preconfigured Web pages
to a hardened PC or a laptop, reducing
software configuration costs. Some automation
platforms can also support video
output of Web pages, allowing the use of
a hardened LCD panel instead of a PC and
further reducing hardware and maintenance
costs.

Alarm Annunciation

Separate hardwired or serially driven
alarm annunciator panels have been
commonly applied in substations to alert
operators of abnormal conditions. These
hardware displays can be replaced with
software-driven displays that are generated
and served out from the automation
platform and viewable as a Web page on
any PC or as video on an LCD monitor.
Displays can be identical to the old hardware-
based displays or can change based
upon real-time operating conditions.

Sequence of Event Recording

Dedicated sequence of event (SOE)
recorders have been applied to determine
the precise sequence of operation of substation
equipment before, during and after
substation events, and to verify proper
operation (to a typical resolution of one
millisecond). The modern automation platform,
combined with high-performance
distributed I/O, can replace the dedicated
recorder with preconfigured Web pages
served out to local or remote PCs. Savings
include reduced wiring costs and reduced
training and configuration time (same
configuration tools and database as RTU,
alarm annunciation and other functions).

The Future

Economic, technological and security
forces will continue to drive the development
and application of the single, powerful
automation platform in transmission
substations. Designs will become easier
to configure and commission, and will
take on new software tasks to convert
data into information, and information
into better operating decisions. These
efficiencies will benefit all utilities, as
they are challenged to contain costs
without sacrificing service.