Analysis: California grid looks at capacity needs

OREANDA-NEWS. March 10, 2015. The California Independent System Operator estimates a shortfall of 941MW of capacity in 2016 in eight relatively congested parts of the grid to comply with the most stringent reliability planning standards, but that deficit should drop to 203MW by 2020.

Grid stakeholders are meeting today in Folsom, California, to discuss the year-ahead and five-year-ahead assessment of local capacity requirements in the areas where grid planners require sufficient local capacity to prevent load shedding. Those include the Greater Bay region with San Francisco, the Los Angeles Basin, San Diego, Fresno and four other secluded, congested load pockets across the California's primary grid.

The 2016 local capacity requirements total 21,326MW for all eight areas for the so-called Category B contingency planning, if a major generating unit shuts down or the largest external source of transmission trips off line. Category B planning includes actions taken by the operator to achieve system configuration changes and generation re-dispatch, avoiding blackouts.

All special planning regions have enough capacity for Category B planning both in 2016 and 2020, according to a presentation by lead regional transmission engineer Catalin Misca.

But the next stage of contingency reserves requirements, associated with the so-called Category C contingencies, result in a cumulative shortage of 941MW in 2016 for five of the regions. Category C involves two consecutive contingencies - generation outages or transmission trips - and North American Electric Reliability Corporation standards allow firm load shedding at this point.

Those reserve requirements drop to only 203MW in 2020, as the grid operator expects load to remain flat or drop because of energy efficiency measures. Additional units are also coming on line, reducing the deficit.

The grid operator will finalize its local capacity needs assessment on 30 April. The grid operator and the Public Utilities Commission will inform state utilities of capacity acquisition requirements associated with the assessment by mid-July. The grid operator can decide to retain units under reliability-must-run contracts or through back-stop procurement if load serving entities do not procure sufficient local capacity in the specified pockets.