"Kirkpatrick, Joe" <joe.kirkpatrick@nrgenergy.com> writes to the NYISO_TECH_EXCHANGE Discussion List:



-----Original Message-----
From: Kirkpatrick, Joe
Sent: Tuesday, July 24, 2001 2:52 PM
To: 'market_relations@nyiso.com'; nyiso_tech_exchange@global2000.net
Subject: RE: just checking..first one never went out


Pre-contingency voltage limits have to be respected in order to validate
any existing interface limits.

As far as I can remember (the memory is the second thing to go)
stability limits are calculated using offline studies. Minimum voltage
limits are part of the study parameters, any voltages experienced in the
R/T that are below the minimum voltage limits used in the offline study
invalidates the stability limits. In other words if you cannot respect
the minimum voltage limits the stability limits are rendered invalid,
system operators do not know if the system can withstand the worst
system contingency as there has been no study to validate the limits at
that new low system voltage.

If a system voltage limit measured at a bus is below the minimum voltage
limit you must increase the bus voltage to the minimum voltage limit,
this is beyond SCD, and I suspect BME and SCUC (to some degree).

If the software cannot resolve the problem then a manual request for
generation or OOM request must be made to resolve it.

That aside the OOM issue is one that needs to be resolved. Some
generation needs to be dispatched OOM to resolve for system problems
that SCD or BME cannot resolve (inherent software deficiencies and
modelling problems), the big question is how do you discern between
legitimate OOM generation requests and other requests that are highly
suspect.

Joe


-----Original Message-----
From: barkerde@nmenergy.com [mailto:barkerde@nmenergy.com]
Sent: Tuesday, July 24, 2001 1:05 PM
To: nyiso_tech_exchange@global2000.net
Subject: just checking..first one never went out



barkerde@nmenergy.com writes to the NYISO_TECH_EXCHANGE Discussion List:



Can anyone tell me the difference between solving for a line constraint
(mw
limit) and a voltage constraint? Could it be that the former uses SCD
and sets
LBMP and the other uses units out of merit and clobbers uplift?