Arkansas Public Service Commission (APSC) staff has concluded that Entergy Arkansas’ proposed 500/161-kV transmission substation and related transmission line terminal facilities, to be located in Craighead County, Ark., are in the public interest.
In April 8 direct testimony on behalf of the general staff of the APSC, Clark Cotten, senior electrical engineer for the general staff, recommended that the APSC grant the company a certificate of public convenience and necessity (CCN) to build, operate and maintain the proposed facilities.
As noted in Cotten’s testimony, Entergy Arkansas filed its application for a CCN last January.
According to the company, the proposed facilities are needed to improve reliability and satisfy “Requirement 2” of NERC Reliability Standard TPL-001-4 as it applies to three planning event categories: P1-2 single contingency loss of a transmission circuit; P2-2 single contingency bus fault; and P2-3 single contingency internal breaker fault. The company noted that the NERC requirements state that analyses of the transmission system performance must confirm that thermal ratings will not be exceeded for events involving any one of those planning event categories.
According to the company, numerous single contingencies on the 161-kV transmission facilities in the Jonesboro area result in power flows that could exceed the applicable thermal ratings and acceptable planning criteria described in the NERC Transmission Planning Standard TPL-001-4 and the company’s local planning criteria.
The proposed facilities would involve the construction of the 500/161-kV transmission substation and associated 500-kV and 161-kV switchyards on property owned by Entergy Arkansas in the northwest quadrant of the intersection of the 161-kV Jonesboro to Jonesboro Hergett and Jonesboro Hergett to Truman transmission lines, and the Independence Steam Electric Station to Dell 500-kV transmission line.
The interconnection of the new 500/161-kV substation will require the six new transmission line segments to be terminated in the new switchyards, two segments for each of the three existing transmission lines, Cotten added.
The total estimated cost for the proposed facilities is $55.9m, he said, adding that Entergy Arkansas will finance the construction with funds available from various sources, including retained earnings.
Entergy Arkansas expects final substation site work to be completed in 3Q16, with substation foundation work for the 500-kV and 161-kV switchyard, as well as related electrical equipment, to be completed in 4Q16. Installation of the 500-kV and 161-kV electrical equipment, autotransformer, and gas insulated switchgear would begin in 1Q17, with the termination of the adjacent 500-kV and 161-kV transmission lines beginning in 2Q17.
Cotten added that final substation and transmission line construction, testing and electrical check-out would be completed in 4Q17. The projected in-service date for the proposed facilities is November 2017, he said.
No major disruptions to existing manmade property uses are expected, Cotten said, adding that the proposed facilities will not adversely impact any private or single-family residences, or interfere with any state or federal national park lands.
Among other things, Cotten said that based on his review of the application and the direct testimonies filed by the company, he concluded that the location of the proposed facilities is reasonable.
In March 15 direct testimony filed with the APSC, Edin Habibovic, manager of expansion planning with the Midcontinent ISO (MISO), said that MISO concurs with Entergy Arkansas’ Transmission Planning Department that the proposed project is needed, and that MISO included the proposed project in the 2015 MISO Transmission Expansion Plan (MTEP).
The proposed project impacts the 161-115-kV bulk electric system, which includes the areas around Walnut Ridge and Jonesboro in the north, and the regions of Newport, Trumann, Harrisburg, Marked Tree, and West Memphis at its southern edge, Habibovic said.
The Independence Steam Electric Station to Dell line overlays upon the 161-115-kV transmission network, and is a major source of injection of power into the underlying network, Habibovic said, adding that the network has a high concentration of load, and is therefore vulnerable to low voltages.
The proposed project successfully improves the reliability of the 161-115-kV transmission network around Jonesboro, Trumann, Newport, Osceola, West Memphis and elsewhere by mitigating certain reliability constraints, Habibovic said.
According to a March 14 APSC order, a hearing on the project is scheduled to be held on May 3 at the commission in Little Rock, Ark.
Entergy Arkansas is a subsidiary of Entergy (NYSE:ETR).