The annual test must be conducted between September 1 and August 31, then is adjusted to the last 5-year average conditions on the date and times of MISO’s coincident Summer peak. There are three types of corrections – air temperature, relative humidity and cooling water temperature. The applicability of these corrections is based on the NERC unit type.
The air temperature and relative humidity corrections apply to:
Combined Cycle (CC) and Combustion Turbine (CT) units.
The cooling water temperature correction applies to:
Combined Cycle (CC)
Fluidized Bed (FB)
Nuclear (NU)and Fossil Steam (ST) units.
Corrections do not apply to Diesel (DS), Hydro (HD) or Pumped Storage (PS) units.
The following MISO guides may be useful: Net Capacity Verification Test or Generation Verification Test Capacity (GVTC) Tips, Dry Bulb Air Temperature and Relative Humidity Correction Example and Cooling Water Temperature Correction Example.
More information on GVTC Testing Requirements can be found in the Resource Adequacy Business Practices Manual (BPM-011) Appendix J.