Southwest Power Pool (SPP) has identified five projects within the Entergy (NYSE:ETR) transmission system that it says merit additional study as potential system upgrades that would “provide enhanced reliability and economic benefits to Entergy transmission system users.”
The projects were identified by SPP serving as Entergy’s independent coordinator of transmission (ITC) and were detailed in SPP’s 2012 ITC Strategic Transmission Expansion Plan (ISTEP) released Nov. 30. The plan seeks to “promote extra-high voltage (EHV) transmission expansion by identifying problem areas and developing long-term strategic solutions” beyond the three-year cost allocation window of Entergy’s construction plan and the ICT’s base plan.
A list of 29 potential projects was presented to stakeholders during July and the top 10 preferred projects were identified. Following further review of the proposed projects, stakeholders participating in a variety of SPP committees and working groups voted for their top five preferred projects.
The projects that were chosen for further study in the ISTEP process are a new 230-kV transmission line from Hartburg, Texas to Sabine, Texas; providing reinforcement for the 500-kV line from Dell, Ark., to San Souci, Ark.; the Amite South reinforcement project in the Baton Rouge to New Orleans, La., area; a new 500/345-kV station at Messick, La., and a new Messick to Dolet Hills 345-kV line; and mitigation of the Franklin, Miss., to Bogalusa 500-kV contingency.
The new Hartburg to Sabine 230-kV line was selected for study to mitigate congestion created by the Hartburg to Cypress 500-kV contingency on the underlying 230-kV system and the Nelson 500/230 kV auto transformer. The Hartburg to Cypress contingency is one of the top transmission constraints in terms of limiting available flowgate capacities (AFCs), long-term transmission service, and transmission loading reliefs (TLRs), according to the report. The project is estimated to cost $52.8m.
Reinforcement of the Dell to San Souci 500-kV line for the loss of the West Memphis, Ark., to Keo 500-kV line was selected to evaluate possible congestion relief solutions in the area. Overload issues were created when the West Memphis to Keo 500-kV line was out of service and weather related issues caused a forced outage of the ISES to Keo 500-kV line. With this forced outage, several underlying 161-kV lines were impacted in the area. According to the report, a new 40-mile Newport to Wynne South 161-kV line should alleviate those issues at an estimated cost of $81.6m.
Stakeholders selected the Amite South Area project as a regional study to evaluate projects to increase transfer capability into the Baton Rouge and New Orleans area, according to the report. While no reliability issues were identified by SPP, transfer issues were identified when SPP, acting as the ICT, performed a 2,000-MW transfer from SPP South to Entergy Louisiana for the Amite South area.
Construction of a new PPG 230/69-kV auto transformer, a rebuild of the PPG to Verdine 230-kV line, a rebuild of the Big Cajun to Addis 230-kV line, and a rebuild of the Rose Bluff to PPG 230-kV line would alleviate the transfer issues and would cost an estimated $51.1m.
Stakeholders selected the new 500/345-kV station at Messick and the Dolet Hills to Messick 345-kV line as a possible solution to increase the east to west transfer capability in the area between Entergy and SPP, the report said.
The area around Messick and Dolet Hills was evaluated under multiple scenarios. After initial review of overloads and possible solutions, SPP determined that the construction of a new 500/345-kV substation at Messick and a new 345-kV transmission line between Messisk to Dolet Hills would improve the east to west transfers. The upgrades are estimated to cost $115.4m.
Stakeholders selected the Franklin to Bogalusa 500-kV because it limits north to south transfers. Possible solutions in the area included reconductoring Big Cajun to Addis 230-kV line, Dow Meter to Dow Cogen 230-kV line, and Hodges to Lucky to Texas East to Sailes 115-kV line. Also included with the solution was to upgrade Willow Glen 500/230-kV auto transformer. The cost of that project is estimated at $76.1m.
The plan was developed under Entergy’s Open-Access Transmission Tariff (OATT).
Accordingly, the Midwest ISO (MISO) will be responsible for planning activities when functional control of Entergy’s transmission system is transferred to MISO, an SPP spokesperson told TransmissionHub Dec. 4.