The
power transfer capability of existing
transmission network
s
can be enhanced
through
the
use
of automated system protection schemes (SPS), which
rapidly respond to disturbances on the network
to keep
the system’s varia
bles wit
hin operational bounds
.
However, r
eliance
on such schemes
may expose the
network to
large impacts
–
including blackouts
–
if the
SPS
does not respond as designed, so the deployment of
SPS should
balance
risks and benefits.
This paper
formulates a risk
-
base
d cost
-
benefit framework
that
allows the operator to strike an optimal balance between
constraint costs and risks of demand curtailment due to
malfunctioning SPS
. It is applied to a simple 4
-
bus power
system inspired by the GB network, for which an exact
o
ptimisation problem can be formulated.
A component
-
based
dependability
model
is developed for the SPS to
determine its failure modes and associated probabilities.
The resulting cost
-
minimisation problem is solved for a
range of operating conditions and SPS
reliability levels
.
The results
consistently
show cost savings from the use of
an SPS, even
if
it is highly unreliable, when a hedging
strategy may be used.
The optimal solution is highly
sensitive to the
problem parameters, but it is
demonstrated
that op
timal operational strategies
are
associated with
particular SPS outcome
s
.
This finding
may be used as empirical guidance to develop operational
strategies for complex networks with unreliable SPS.