Ken,

Thanks for the opportunity to review the initial studies performed by the 
ERCOT
System Planning Technical Operations group and to have the opportunity to
comment on them at the January 31, 2001 CSC meeting.

After I began reviewing the reports that you sent out, I noticed the need for
the following items to be addressed quickly in order for all market 
participants
(including ERCOT) to perform meaningful transmission studies:

1)  A listing of single element contingencies that PSS/E and/or MUST performs
that aren't valid (phantom) contingencies from a physical perspective (i.e. 
the
protection schemes in place would not allow this issue to occur anyway).  The
easiest to explain example of this situation is when parallel step up
transformers are used at a power plant.  When one transformer is outaged by
automatic single element contingency functions of PSS/E or MUST, the remaining
transformer is reported to experience massive overloads that aren't really
relevant since the protection scheme in place wouldn't allow this to 
physically
occur.  While step up transformers of this nature can easily be screened from
the output of PSS/E and MUST, other phantom contingencies that are reported on
transmission line outages can't be.  This listing of phantom contingencies
should be developed and stored in such a fashion that allows it to be included
in PSS/E and/or MUST runs as an exception file of contingencies to be ignored.
A separate file should be maintained and posted on the ERCOT website for each 
of
the dataset A & B cases that are prepared annually.

2)  A listing by load flow bus number of all special contingencies that should
be included in PSS/E and/or MUST simulations to reflect the actual response of
protection schemes in place needs to be provided by the TPs.  A simple example
of a special contingency from a PSS/E and/or MUST stand point that is really a
single contingency from a physical system stand point is when an 
autotransformer
is connected to the line side of a breaker in a station, rather than to the
station bus.  PSS/E and MUST needs to be instructed to remove both components 
at
the same time in order to accurately simulate what is really a single
contingency from a physical perspective.  A separate file should be maintained
and posted on the ERCOT website for each of the dataset A & B cases that are
prepared annually.

3)  A listing by load flow bus number of all double circuit lines that are
greater than 0.5 miles in length needs to be provided by the TPs.  This 
listing
is needed by market participants to simulate ATC during severe weather
situations and for evaluating planned transmission additions using PSS/E 
and/or
MUST.  A separate file should be maintained and posted on the ERCOT website 
for
each of the dataset A & B cases that are prepared annually.

4)  A listing of valid operator actions that will be taken to alleviate post
contingency overloads should be provided by the TPs in a format that is
compatible with PSS/E and/or MUST.  A separate file should be maintained and
posted on the ERCOT website for each of the dataset A & B cases that are
prepared annually.


In addition, the following requested information would better allow all market
participants to understand the planned expansion and operation of the ERCOT
transmission system:

1)  Prepare an annual transmission plan document that is posted on the ERCOT
website which graphically and verbally illustrates the following aspects of
proposed projects: location, electrical connectivity (i.e. one-line
representation), estimated cost, anticipated system benefits, and proposed
in-service date.  The projects proposed and described in this expansion plan
document should be of the same scope and timing as the ones modeled in the 
SSTF
dataset A & B cases.  Ideally, this document would be posted annually on the
website at the same time as the dataset A & B cases.  The California ISO
currently provides this information on their website at the following address:
http://www.caiso.com/thegrid/planning/transassessments/.

2)  Prepare an annual document that will be posted on the ERCOT website, which
explains how the commercially significant constraints (CSCs) will be handled
(i.e. preventative generation redispatch or post contingency operator action 
to
reconfigure the transmission system through opening or closing breakers).


To the degree that is possible, please include these issues in your agenda for
discussion at the January 31, 2001 CSC meeting.  Thanks

Shannon Caraway, P.E.
TXU Energy Trading
(214) 875 9397
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