<s>
Power	B-Application
System	I-Application
Simulator	I-Application
for	I-Application
Engineering	I-Application
(	O
PSS®E	O
—	O
often	O
written	O
as	O
PSS/E	B-Application
)	O
is	O
a	O
software	O
tool	O
used	O
by	O
power	O
system	O
engineers	O
to	O
simulate	O
electrical	O
power	O
transmission	O
networks	O
in	O
steady-state	O
conditions	O
as	O
well	O
as	O
over	O
timescales	O
of	O
a	O
few	O
seconds	O
to	O
tens	O
of	O
seconds	O
.	O
</s>
<s>
Since	O
its	O
introduction	O
in	O
1976	O
,	O
it	O
has	O
evolved	O
from	O
a	O
simple	O
command-line	B-Application
interface	I-Application
,	O
to	O
an	O
integrated	O
,	O
interactive	O
program	O
for	O
simulating	O
,	O
analyzing	O
,	O
and	O
optimizing	O
power	O
system	O
performance	O
,	O
and	O
it	O
can	O
provide	O
probabilistic	O
and	O
dynamic	O
modeling	O
features	O
.	O
</s>
