Nevada Power Company OASIS

Nevada Power Company Policy on Transmission Reliability Margin and Capacity Benefit Margin

Effective Date:   09/24/2007

Date last Re-evaluated:  09/24/2007

Definitions

According to the Western Electricity Coordinating Council (WECC) document, Determination of Available Transfer Capability within the Western Interconnection, the definitions for Transmission Reliability Margin (TRM) and Capacity Benefit Margin (CBM) are: 

TRM

“TRM is the amount of transmission transfer capability necessary to provide a reasonable level of assurance that the interconnected transmission network will be secure under a broad range of uncertainties in system conditions. TRM accounts for the inherent uncertainty in system conditions and system modeling, and the need for operating flexibility to ensure reliable system operation as system conditions change.”

 Further, the Document specifically addresses possible TRM components. They are: 

1.      Transmission necessary for the activation of operating reserves

2.      Unplanned transmission outages (for paths in which contingencies have not already been considered in establishing the path rating)

3.      Simultaneous limitations associated with operation under a nomogram

4.      Loading variations due to balancing of generation and load

5.      Uncertainty in load distribution and/or load forecast

6.      Allowances for unscheduled flow

CBM

“CBM is the amount of firm transmission transfer capability reserved by Load Serving Entities (LSEs) on the host transmission system where their load and generation resources are located, to enable access to generation from interconnected systems to meet generation reliability requirements. CBM is a uni-directional quantity with identifiable beneficiaries, and its use is intended only for the time of emergency generation deficiencies.”

Nevada Power Company Policy---TRM

Nevada Power Company (NEVP) utilizes TRM specifically for reserve sharing.

NEVP is a member of the Southwestern Reserve Sharing Group (SRSG).  SRSG exists to allow member control areas/balancing areas to reduce the contingency reserves they may carry and allow access to other reserves to meet the requirements of the NERC Disturbance Control Standard (DCS) detailed in BAL-002-0.

NEVP has two paths to import or export contingency reserves: 1) Crystal 500 – NEVPSYS and 2) Mead230 – NEVPSYS.  The TRM values are defined by SRSG participant delivery commitments and, as such, are held constant throughout the year.

The Transmission Provider will assess the TTC and the ATC of the Transmission System to provide the service requested as prescribed by FERC regulations and in accordance with the process detailed in Sections 4 and 5 of the Transmission Provider's annual FERC Form 715 submittal.  In determining the level of capacity available for new transmission service requests, the Transmission Provider will take into consideration that capacity needed to meet current and reasonably forecasted loads of Native Load Customers, existing Network Customers, existing Firm Point-To-Point Transmission Service Transmission Customers, pending applications for Firm Point-To-Point Transmission Service, and other existing contracts.

Nevada Power Company Policy---CBM

Nevada Power Company does not use CBM.

Re-evaluation

Nevada Power Company will re-evaluate TRM needs annually.  Currently Nevada Power does not use CBM, and will re-evaluate CBM as it is requested by Transmission Customers as well as CBM will be re-evaluated at a minimum annually.

Contact
Rahn Sorensen
702-862-7208
rsorensen@nevp.com