US approves rules aimed at grid planning for extreme weather

The US Federal Energy Regulatory Commission (FERC) has finalized two rules that it said would help improve reliability of the bulk power system against threats of extreme weather that may cause risk to life and economic harm.

The first rule directs the North American Electric Reliability Corporation (NERC) to develop a new or modified reliability standard to require transmission system planning for extreme heat and cold weather conditions over wide geographical areas, including studying the impact of concurrent failures of bulk power system generation and transmission equipment and implementing corrective actions as needed. 

The second rule directs transmission providers to submit one-time reports describing their policies and processes for conducting extreme weather vulnerability assessments and identifying mitigation strategies.

FERC Chairman Willie Phillips said the commission’s June 15 action marked the first time reliability standards would require planning for extreme heat and cold weather.

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The new rules stem from the Commission’s June 2021 technical conference on Climate Change, Extreme Weather and Electric System Reliability. And preliminary assessments from the FERC and NERC teams studying the December 2022 Winter Storm Elliott, underscored the need for the new rules.

Since 2011, the country has experienced at least seven major extreme weather events, each of which stressed electric grid operations, FERC said.

In mid-May, NERC issued a Level 3 Alert that called for essential actions for cold weather preparations for extreme weather events. It said the alert was intended to increase the Reliability Coordinators’ (RC), Balancing Authorities’ (BA), Transmission Operators’ (TOP), and Generator Owners’ (GO) readiness and enhance plans for, and progress toward, mitigating risk for the upcoming winter and beyond.

In issuing the alert, NERC said the resource mix is undergoing significant, rapid change. The system is becoming more reliant on variable energy resources and natural gas. Extreme winter weather events have stressed the supply of traditional fuels and the dependability of new resources. NERC said that preparing resources to operate during extreme winter weather and achieving situational awareness in both planning and operations “is necessary for optimal reliability.”

Addressing three concerns

Both rules approved by the FERC in mid-lune take effect 90 days after publication in the Federal Register. Each transmission provider must file the one-time informational report required by the second final rule, 120 days after publication in the Federal Register.

The first draft final rule directs NERC to develop a new Reliability Standard or modifications to the current transmission planning Reliability Standard, TPL-001-5.1.  NERC would be directed to address three major concerns. 

First, the draft rule requires the proposed standard to define benchmark events based on prior extreme heat and cold weather events and/or future meteorological projections. 

Second, the proposed standard must require planning entities to develop planning cases for extreme heat and cold weather events using “steady state and transient stability analyses” that cover a range of extreme weather scenarios, including the expected resource mix’s availability during extreme weather conditions and the wide-area impacts of extreme weather.  

Third, to the extent these planning studies discover specified instances when performance requirements during extreme heat and cold weather events are not met, the proposed standard must require planners to develop corrective action plans to allow the performance requirements to be met.  

The second draft final rule would require a one-time report on how transmission providers assess the impacts of extreme weather on their transmission assets and operations.  Transmission providers would report how they:  1) establish a scope; 2) develop inputs; 3) identify vulnerabilities and exposure to extreme weather hazards; 4) estimate the costs of impacts; and 5) use the results of vulnerability assessments to develop risk mitigation measures.  

The reports are expected to provide FERC with a fuller record as to whether and how transmission providers assess and mitigate vulnerabilities to extreme weather and will enable coordination among transmission providers as well as information sharing on best practices. 

More information is available here.

Originally published on power-grid.com