Comparisons of CDR Report and Transmission Planning Models CDR Report Transmission Planning Models SSWG Models RTP Reliability Models RTP Economic Models Purpose Provide an estimate of the planning reserve margin during summer and winter peak load seasons Provide a range of power flow cases with a common reference point for ERCOT and Market Participants Provide power flow cases for use in developing the reliability portion of the ERCOT Regional Transmission Plan (RTP) Provide a power flow case for use in developing the economic assessment portion of the ERCOT Regional Transmission Plan (RTP) Load Forecast Inputs Preparer ERCOT TSPs ERCOT and TSPs ERCOT Season Summer and Winter Four seasons for current year Summer peak for next 6 years Minimum load and high wind for a future year Summer peak for future Years 1, 3, 5, and 6 Full year hourly analysis for Future Years 3 and 6 Weather Assumptions Average weather (expect actual load to exceed forecast one out of two years) Varies by TSP, see Appendix A Higher of: Summed TSP SSWG case loads in each weather zone; or ERCOT 90th percentile forecast by weather zone (expect actual load to exceed forecast one out of ten years) “Average” weather in each weather zone (expect actual load to exceed forecast one out of two years) Load Coincidence Coincident (single peak load hour for ERCOT Region) Based on ALDR forecast, TSPs use varied methods for populating loads by individual substation (see Appendix A for description by TSP) Peak load by individual substation for each weather zone (non-coincident), with exceptions made depending on the case Non-Coincident by weather zone
Load Resource and other Demand Response Programs Included (shown as separate line item) Not Included Not included Not Included Self-Serve Load Net to the grid (self-serve load minus generation) Gross (no reduction for self-serve generation) Gross (no reduction for self-serve generation) Gross (no reduction for self-serve generation) Load Adjustments None No adjustments from TSP provided loads are made Within a region of study the higher of: SSWG load in each weather zone or ERCOT 90th percentile load forecast by weather zone Adjustments may be made outside of study region None Generation Inputs Extraordinary Dispatch Methods – a method of adding capacity to a model Not applicable As needed, see Appendix B of SSWG manual. Has been used for years 4, 5, and 6 in recent years Yes, a combination of extraordinary dispatch and load scaling outside of the region being studied may occur Not applicable Wind Generation Capacity contribution based on average of recent output (top 20 load hours) 100% of capacity modeled. Units dispatched according to CDR Report unless needed in extraordinary dispatch 100% of capacity modeled. Units dispatched at varying levels, depending on the case Units dispatched based on representative hourly patterns appropriate for weather assumptions season serve
Solar Generation 100% of capacity reported 100% of capacity modeled. Units dispatched based on review of historic seasonal output 100% of capacity modeled. Units dispatched at 70% of capacity Units dispatched based on representative hourly patterns appropriate for weather assumptions; using vendor profiles DC-Ties Output levels based on average of recent peak-season output (top 20 load hours) 100% of capacity modeled. Units dispatched based on review of historic seasonal operating levels 100% of capacity modeled. Units dispatched based on review of historic seasonal operating levels Units dispatched based on historical hourly patterns Hydro Generation Output levels based on average of recent peak-season output (top 20 load hours) 100% of capacity modeled. Units modeled offline 100% of capacity modeled. Units modeled offline Units dispatched based on historical hourly patterns Requirements for Including Planned Generation Signed interconnection agreement; Air permits (if needed); and Cooling water attestation Planning Guide 6.9. Signed interconnection agreement; Air permits (if needed); Cooling water attestation; and Full financial commitment and notice to proceed given to TSP Planning Guide 6.9. Signed interconnection agreement; Air permits (if needed); Cooling water attestation; and Full financial commitment and notice to proceed given to TSP Planning Guide 6.9. Signed interconnection agreement; Air permits (if needed); Cooling water attestation; and Full financial commitment and notice to proceed given to TSP Self-Serve Generation Net to grid during peak hours of recent peak Full capacity available Full capacity available Full capacity available Switchable Units Capacity contracted to other region is not included Capacity contracted to other region is considered unavailable Capacity contracted to other region is considered unavailable Capacity contracted to other region is considered unavailable Mothball Generation Capacity is included if unit owner states likelihood of return is greater than 50% Designated as a mothball unit and status set to unless needed for Mothball units not available (new for 2015 as a result of TPL-001-4) Mothball units not available