California readies itself for a summer without San Onofre nuclear plant

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Progress is being made on more than a half-dozen upgrades to the transmission system in Southern California that are intended to help address supply adequacy issues that could result from Southern California Edison’s (SCE) June 7 decision not to reopen the San Onofre Nuclear Generating Station (SONGS).

On the heels of SCE’s announcement, officials with the California ISO (Cal-ISO) made the prediction that the state as a whole would be in “reasonably good shape this summer, even without SONGS'” 2,200 MW of generating capacity, except in southern Orange County and in San Diego, where Cal-ISO expected transmission constraints to result in challenges to importing the power needed.

The projects, many of which are aimed at alleviating those constraints, were presented to the ISO’s board of governors in February and have either been completed or are nearing completion by the various companies and utilities involved.

Projects include the conversion of Huntington Beach generating units 3 and 4 into synchronous condensers. Cal-ISO CEO Steve Berberich said on June 7 those condensers are scheduled to come online on June 26, ahead of the above-average temperatures some are already forecasting for the area during July and August.

System upgrades include additions to several substations. Additional 80 MVAR capacitors at SCE’s Santiago and Johanna substations and a 160 MVAR capacitor at the Viejo substation are operational.

Two San Diego Gas & Electric (SDG&E) substations will also see enhancements. A 230/138 kV transformer will be added to the utility’s Encina substation just south of San Onofre and a 230 kV capacitor will be added to its Penasquitos substation this summer. Other system upgrades, including the 2012 energization of the Sunrise PowerLink, have already increased SDG&E’s import capacity from 2,100 MW on June 17, 2012, to 3,350 MW today, an SDG&E spokesperson told TransmissionHub June 12.

Another project involves an upgrade to the Barre-Ellis 220-kV transmission line, which will be split from two circuits into four to provide additional redundancy. Approved in 2012, the project has been fast-tracked and is expected to be completed by June 15, a Cal-ISO spokesperson told TransmissionHub.

While primarily transmission-related, system upgrades also include the addition of three new natural gas-fired generation resources.

The Sentinel Energy Project near Desert Hot Springs, Calif., began adding 800 MW of energy to the Cal-ISO grid when it entered service in May, some three months ahead of schedule. The project is jointly owned by Competitive Power Ventures, GE Energy Financial Services, and Diamond Generating Corporation, a wholly owned subsidiary of Mitsubishi Corporation.

The Walnut Creek Energy Center in City of Industry, Calif., includes 500 MW of new generation, 10% more than the 452 MW lost by reconfiguring the Huntington Beach units. Built by a subsidiary of Edison Mission Energy, the plant entered commercial service on June 1, an Edison Mission spokesperson told TransmissionHub June 12.

NRG Energy’s 560 MW El Segundo Power Redevelopment project will replace the retired El Segundo Unit 3’s 335 MW and bring an additional 225 MW to the system. It is expected to enter service by June 30, according to the Cal-ISO spokesperson.

However, Berberich cautioned again reading too much into the value of those added megawatts because the generating units are “outside of the specific, local area that San Onofre is in, and they’re still constrained by transmission.”

Cal-ISO on June 10 published on its website a map of the southern portion of the L.A. basin and the San Diego areas, the area of greatest concern. The map also identified SDG&E’s Sunrise PowerLink and Southwest Powerlink as among the non-generation alternatives that will mitigate load-shed risk for multiple contingency events with the continuing outage of SONGS, according to Cal-ISO. Taken together, those solutions “address reliability needs without excessive reliance on load-dropping schemes,” the grid operator said.

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April 2015
Volume 19, Issue 4

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