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Enron Mail |
"Kirkpatrick, Joe" <joe.kirkpatrick@nrgenergy.com< writes to the NYISO_TECH_EXCHANGE Discussion List: 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?
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