1. Enoch Davies Associate Engineer Composite Load Model Implementation January 19, 2012 Salt Lake City, UT

2. 2 More realistic model o Recognizes the electrical distance between transmission buses and loads o Recognizes diversity of end-use characteristics, including geographical and seasonal diversity  Fans  Pumps  Air Conditioners  Various industrial loads Composite Load Model

3. 3 Multiple Phase Plan o Phase 1  To be completed in July of 2012  Composite load model in WECC data sets with AC stalling disabled  Upon completion, review voltage dip criteria required o Phase 2  Full composite load representation Implementation Plan

4. 4 Phase 1 o Replace the ten year old interim load model (20% induction motor load) with comp load model  Stalling feature of single phase AC disabled (FIDVR) o Available in 2012 heavy summer 4 and light summer 1 operating cases for review o Model still consistent with the current voltage dip criteria Implementation Plan cont.

5. 5 Phase 2 o Fully functional composite load model implemented in all WECC data sets o Review of WECC voltage dip criteria would be needed before phase 2 could be implemented Implementation Plan cont.

6. 6 Implementation Plan Requirements RequirementPhase 1Phase 2 Composite load model is implemented in GE PSLF and Siemens PTI PSS®E programs Yes WECC-wide data sets are providedYes Tools are developed for load model data managementYes Air-conditioner stalling phenomenon is modeledNoYes Performed model validation studiesYes*Yes Performed system impact studiesYes*Yes Understanding of load responses to unbalanced faultsNoYes Revision of WECC voltage dip criteriaNoYes *for events that do not involve AC stalling

7. 7 Highlights (Implementation Plan)Implementation Plan o 2012 summer operating cases have composite load model data available o Utilities evaluate Path Ratings/TPL Studies – March 2012 o RS Meeting – Member Reports/Status Update – May 2012 o July 2012 PCC meeting Phase 1 composite load model implemented in WECC data sets Implementation Plan Timeline

8. Enoch Davies Associate Engineer enoch@wecc.biz Questions?