Compare and Contrast Reliability Assumptions Bob Pierce May 12, 2006

Education Process Shared and discussed transmission planning practices among Participants Identified similarities and differences in the reliability assumptions used by PEC and Duke in their transmission planning processes DRAFT

Primary Differences Planning Process Calendar Case Development Assessment Practices DRAFT

Planning Process Calendar PEC divides screening into two sets of studies: near-term (1-5 yrs) performed during the 1st quarter long-term (6-10 yrs) performed in the 3rd quarter Duke does not divide the screening process into near-term and long-term DRAFT

Case Development: Rollover and Future DNRs Duke includes Designated Network Resource (“DNR”) projections provided by the Load Serving Entities (“LSEs”) in the base cases PEC assumes roll-over of existing DNRs, but does not include changes to existing DNRs or new DNRs in base cases until the Open Access Transmission Tariff (“OATT”) requirements, initiated by Open Access Same-time Information System (“OASIS”) requests, are completed DRAFT

Case Development: Dispatch Priority Duke’s base cases assume a dispatch priority of LSE resources provided by the LSEs PEC’s base cases include all LSE imports flow and owned generation PEC on system resources are backed down to accommodate full use of LSE resources DRAFT

Case Development: Future “Dummy” Generation Duke locates dummy generation at buses based on knowledge gained from the generator interconnection queue regarding feasible locations PEC locates dummy generation at a 500 kV bus to reduce the impact it may have on the system There are sufficient resources to serve the load in the control areas in the 2011 case, therefore location of dummy generation is not an issue DRAFT

Case Development: Transmission Reliability Margin (“TRM”) Both Duke and PEC reserve VACAR Reserve Sharing on respective interfaces In addition, PEC: Includes a parallel path component Uses a system inrush response on non-VACAR interfaces DRAFT

Assessment: Ratings Used for Analysis Duke uses 12-hour and long term emergency (seasonal) ratings for contingency analysis PEC uses the continuous rating for all contingency analysis Minor differences between Duke and PEC in the assumptions made in determining the continuous ratings of lines and transformers DRAFT

Assessment: Import Assumptions Duke does not import for the loss of one generator For the outage of two generators, Duke’s assessment imports the amount of the 2nd generator outage PEC assesses with all import obligations, including TRM DRAFT

Assessment: Contingency Assumptions Duke assesses a generator maintenance case plus an additional generator outage PEC assesses a generator contingency plus unit derations replaced by TRM imports DRAFT

Assessment: Phase Angle Due to the impact on phase angle from significant 500 kV flow, PEC monitors the Richmond-Newport 500 kV line phase angle Duke does not currently monitor phase angle DRAFT

Conclusions The comparison of Duke’s and PEC’s reliability planning practices includes many similarities; but there are some differences The consequences associated with resolving some of these differences are complex For the first Collaborative Plan, the PWG will not change planning practices for the 2006 plan, except to adjust the planning process calendar The PWG will assess impacts of the differences and may recommend changes as the joint studies proceed DRAFT