By Rich Heidorn Jr.

Coal plant retirements have not caused a shortage of black start resources, but grid operators should consider expanded testing, FERC and NERC said last week.

NERC, its eight Regional Entities and the commission released a study May 2 based on information from a representative sample of nine volunteer registered entities, a follow-up to a 2016 joint report. (See Utilities’ Restoration Plans Pass FERC, NERC Review.)

“Although some participants have experienced a decrease in the availability of black start resources due to retirement of black start-capable units over the past decade, the joint study team found that the participants have verified they currently have sufficient black start resources in their system restoration plans, as well as comprehensive strategies for mitigating against loss of any additional black start resources going forward,” the new report says. “The joint study team also found that participants that have performed expanded testing of black start capability, including testing energization of the next-start generating unit, gained valuable knowledge that was used to modify, update and improve their system restoration plans.”

A next-start unit is the first generator in the cranking path to be energized using power from the black start generator.

The report recommends that:

• Black start generators dependent on a single fuel develop alternative fuel capability or take other steps such as signing firm pipeline contracts. “Furthermore, the joint study team recommends that these black start resource owners work with their regulators as necessary, to develop alternative solutions to address potential fuel constraints.”
• RTOs and ISOs consider further study of the adequacy of compensation for black start and other resources supporting system restoration, “including any potential threat or impact on black start resource procurement and retention under current compensation mechanisms.”
• Grid operators coordinate transmission and generation registered entities to verify model data and ensure the accuracy of black start simulations. “The joint study team recommends that registered entities performing simulations of their system restoration plans, especially those with cranking path auxiliary loads at a next-start generating unit that are large relative to the black start unit, closely coordinate with generator owner(s) to ensure that the associated modeling data used to perform restoration plan simulations [are] accurate. For instance, the dynamic simulations should include energizing the cranking path and next-start generating unit start-up, using generator and load models that have been verified against electrical data captured during various normal system operations or disturbances.”
• Transmission operators perform expanded testing of black start cranking paths, including testing during planned maintenance outages.

The report emphasized that its recommendations — while “appropriate for all registered entities responsible for system restoration” — are voluntary and “not subject to mandatory compliance with the recommendations, separate and apart from any obligations of mandatory reliability standards.”

The report also noted “beneficial practices” used by some that may not be universally appropriate. “The joint study team recommends that registered entities consider incorporating these practices, or variations thereof, as appropriate,” it said.

These practices included:

• Coordinating the use of black start facilities across multiple transmission service footprints, allowing a black start unit to aid an adjacent area’s critical load.
• Providing additional personnel to staff substations and perform safety watches on transmission lines during expanded testing. “At control centers, additional operators would manage and coordinate expanded testing so that system operators can focus on essential system operations with minimal distractions.”
• Having black start generators sign agreements with next-start units to facilitate expanded testing.