Mississippi regulators approve Entergy Mississippi’s proposed 115-kV rebuild project

According to the direct testimony of Milton Watts, a manager in the Project Management and Construction Department for ESL, the total estimated cost of the proposed electrical facilities is $27m

The Mississippi Public Service Commission, in a June 11 order, granted to Entergy’s (NYSE:ETR) Entergy Mississippi a certificate of public convenience and necessity (CCN) to acquire, build, expand, operate, own, and maintain proposed electrical facilities in Simpson and Rankin counties.

As noted in the order, Entergy Mississippi in February filed a petition for a CCN seeking commission authorization to rebuild a 15-mile section of the South Jackson-Magee 115-kV transmission circuit from the Star substation to the Mendenhall substation – referred to as the Star-Mendenhall 115-kV Line Rebuild project – as well as a 10-mile section of the South Jackson-Magee 115-kV transmission circuit from the Mendenhall substation to the Magee substation – referred to as the Mendenhall-Magee 115-kV Line Rebuild project.

The company requested in its petition that the commission grant it a CCN to acquire, build, expand, own, operate, and maintain the proposed electrical facilities, including:

  • Rebuilding a 15-mile section of the South Jackson-Magee 115-kV transmission circuit from the Star substation to the Mendenhall substation to achieve at least a 259 MVA through path rating. The line will be rebuilt with all new vertical steel, self-supporting, single-circuit configurations utilizing the existing right of way (ROW). Fiber communications will be added along the rebuilt line
  • Rebuilding a 10-mile section of the South Jackson-Magee 115-kV transmission circuit from the Mendenhall substation to the Magee substation to achieve at least a 259 MVA through path rating. The line will be rebuilt with all new vertical steel, self-supporting, single-circuit configurations utilizing the existing ROW. Fiber communications will be added along the rebuilt line

The commission also noted that the Mendenhall-Magee 115-kV Line Rebuild project will begin at the completion of the Star-Mendenhall 115-kV Line Rebuild project.

The commission noted that during the construction phase, the Entergy Mississippi fiber-optic network will be extended from the Star 115-kV substation to the Magee 115-kV substation, providing a path for relaying and communication purposes between Jackson and Magee.

Entergy Mississippi is proposing to build the electrical facilities to maintain compliance with NERC requirements, as well as to continue delivering reliable electrical service to its customers in south central Mississippi. The commission added that according to direct testimony filed in the matter by Chad Ladner, manager for Transmission Planning for Entergy Services, LLC (ESL), the proposed electrical facilities are needed as a corrective action plan to ensure continued reliability per the mandatory NERC Reliability Standards as a result of a category P1-2 contingency (“Single Contingency Loss of a Transmission Circuit”), which in this case would be the simulated loss of the Choctaw-Clay TVA 500-kV line.

Ladner noted that transmission studies conducted by the Midcontinent ISO (MISO) and by the Transmission Planning group at ESL showed that the loss of the Choctaw-Clay TVA 500-kV transmission line could result in thermal overloading on the Star-Mendenhall 115-kV and Mendenhall-Magee 115-kV line sections, the commission said.

Ladner noted that MISO planning personnel determined that the proposed electrical facilities provide the most effective alternative to remedy the identified limitations, and that the MISO Board of Directors approved the proposed electrical facilities in December 2018.

According to the direct testimony of Milton Watts, a manager in the Project Management and Construction Department for ESL, the total estimated cost of the proposed electrical facilities is $27m. The project is planned for the Star-Mendenhall 115-kV Line Rebuild project to be operational by June 2020, and for the Mendenhall-Magee 115-kV Line Rebuild project to be operational by December 2020, subject to the receipt of necessary permits and required approvals, according to Watts.

The commission also said that there is substantial evidence in the proceeding to determine that there is a need for Entergy Mississippi to build and install the proposed electrical facilities, which are necessary to maintain transmission operations reliability and to meet mandatory NERC requirements.

About Corina Rivera-Linares 2807 Articles
Corina Rivera-Linares, chief editor for TransmissionHub, has covered the U.S. power industry for the past 13 years. Before joining TransmissionHub, Corina covered renewable energy and environmental issues, as well as transmission, generation, regulation, legislation and ISO/RTO matters at SNL Financial. She has also covered such topics as health, politics and education for weekly newspapers and national magazines. She can be reached at corinar@pennwell.com.