IEEE Power & Energy Magazine - May/June 2014 - 83

With its automatic downloading functionality,
the arming system can periodically update the RASA patterns
at all arming stations.

by TsaPM and downloads them automatically to rTUs
and Plcs at arming stations. Under certain predefined
"exceptional conditions" of the eMs applications and/
or power system operations, the automatic download will
be suspended, and an alarm will be enunciated instructing operators to investigate the cause of the suspension
alarms (see figure 8).
figure 7 is a functional diagram of the integrated eMs/
ras system that automates in real time the entire process
from rasa to actual ras actions when contingencies
occur. The system is fully redundant for single-point failure.

TSAPM and RASA Functionality
Within the eMs environment, TsaPM as an agent of decision making in determining the rasa patterns is driven either
by the real-time sequence (periodically) or by manual execution. rasa is driven by TsaPM running in the background
as a server for downloading rasa patterns. in this section, we
describe some architectural details of these applications.

TSAPM Functionality

system condition. each of the predefined templates contains a
number of rules for calculations, implemented by a deck file.
as shown in figure 9, TsaPM's execution of these deck
files produces two sets of outputs. one set consists of preventive action plans for operators and the other of corrective
action plans for ras schemes:
✔ preoutage restrictions (preventive action plans),
including transfer limits and operation guidelines presented as alarm messages
✔ recommended rasa patterns (corrective action plans),
including arming patterns for load shedding, generation
shedding, line tripping, and shunt switching.
in general, a generation-shedding specification for a contingency consists mainly of the following elements:
✔ an amount of MW to be reduced by generation shedding (amount of security enhancement)
✔ the arming priority of plants that participate in generation shedding
✔ the arming priority of units within a plant that participate in generation shedding
✔ a minimum number of units in the plants associated
with ras schemes that must be kept online after generation shedding to maintain voltage control capability for the postcontingency systems
✔ distribution factors of the plants (defined as a ratio of
the total MW contribution of generation shedding at a

TsaPM is implemented using study results from extensive offline planning studies, which include rules of transfer limit calculations, generation-shedding requirements, and other rasa
requirements based on the precontingency power system conditions (topology and power flow). figure 5 shows a typical
generation-shedding requirement
as specified in system operating
orders, codified in TsaPM's "deck
Off-Line Planning Study
file" as a subroutine using a combination of a scripting language,
fortran, and c. There are more than
500 such deck files in TsaPM so
far; these are constantly growing in
Templates
Rules of
(Predefined
size, number, and complexity.
Calculations
System Condition)
a pattern-matching technique is
used to pick up the results that most
closely match real-time conditions.
Rules
TsaPM compares the precontinSelected
gency power system condition, as
SE Solution-Current
represented by a state estimator soSystem Condition
lution in real time or a power flow
Template Selected
solution in study mode, with a set of
predefined "templates." The solution algorithm selects the template
that best matches the current power figure 9. A functional diagram of TSAPM.
may/june 2014

Preoutage
Restrictions
Recommended
RAS Arming
Pattern

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Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - May/June 2014
