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MISO (mEYE-so)

Use MISO in all references to our corporate name

Additional Information 

Emergency Operations FAQ 

MISO Operating Procedures

Current Grid Conditions

Winter 2021-2022 Primer

The electrical grid is an interconnected network for delivering electricity from producers to consumers. It consists of generating stations that produce electrical power, high voltage transmission lines that deliver electricity to sub-stations,  and distribution lines that deliver power to homes, schools and business.

As a grid operator, MISO's role is to ensure the right amount of electricity is generated minute by minute and transmitted safely and reliably across the high-voltage transmission lines. Local utilities are responsible to safely and reliably deliver the electricity to their customers.

MISO does not own any equipment on the bulk electric system. Our members do. MISO manages the generation of electricity and the transmission of electricity across high-voltage power lines. 

MISO is a Regional Transmission Organization (RTO) responsible for doing three things:

  1. Manage the bulk electric grid across its region
  2. Manage the buying and selling of electricity within its region
  3. Plan for the grid of tomorrow

MISO's role and responsibilities can be compared to those of an air traffic controller. Air traffic controllers are responsible for ensuring planes get from point A to point B safely and reliably 24/7/365. They don't own the planes, they don't own the runways, they don't own the terminals. They simply manage the movement of planes.

MISO manages the movement of electrons across the bulk electric system 24/7/365. From generation to transmission. MISO does not own the generators, the transmission towers, or the transmission lines. Our members do.

MISO makes sure the right amount of electricity is generated and transmitted to our member utilities who are responsible for delivering the power to their customers.

Preparing for the possibility of extreme weather impacting the grid is a year-round task. That's why MISO conducts coordinated seasonal assessments, readiness workshops, and emergency procedures drills on an on-going basis. To note some examples: 

  • MISO conducts annual Winter Readiness Workshops to prepare for the upcoming season
  • MISO conducts regular drills to identify potential challenges and develop solutions
  • MISO conducts fuel surveys and assessments with its members to determine potential risks
  • MISO conducts after-action event reviews and integrates learnings into future workshops, drills, and operational practices
  • MISO coordinates regular communications with its members and neighbors

When severe weather is forecasted for the MISO region, operators can issue informational advisories and cold weather alerts to prepare for changing grid conditions. We coordinate daily with neighbors and members to discuss generation and fuel availability. If necessary, MISO can declare "Conservative Operations," which is a set of instructions designed to maximize MISO's ability to operate the bulk electric system reliably during abnormal conditions. 

Extreme winter conditions can contribute to significant losses of electric generation through a variety of factors. Cold temperatures can freeze equipment for various types of electric generators. Frozen transportation equipment and facilities can inhibit MISO generators from obtaining fuel.

MISO believes plant operations personnel should evaluate all equipment that can be impacted by winter weather and advises generator operators to utilize NERC’s winter generator reliability guidelines when preparing for and operating in severe cold weather conditions. More information can be found in our Winterization Guidelines.

The current outlook shows an adequate amount of resources available to meet winter demand – with total probable capacity of around 106 gigawatts. The load-serving entities (local utilities) operating within the MISO region project a winter peak of about 101 gigawatts.

Although weather forecasters anticipate an overall average winter for the region, MISO has identified and is acting upon two areas of potential risk: extreme weather and fuel supplies.

  • Even if predictions of an average/moderate winter are correct, it is likely that the region will experience periods of extreme weather.
  • The potential for high electricity demand coupled with high outage scenarios due to an extreme cold weather event could drive operational challenges including a need to access emergency procedures.
  • MISO’s data shows elevated fuel supply risks for thermal generation, particularly coal. This is driven by a combination of increased coal demand due to high gas prices, decreased coal supply due to downsizing of the coal industry, and supply chain transportation challenges.

MISO has a set of emergency operating plans to address conditions like extreme weather that can negatively impact grid. During winter, severe weather conditions can keep generators from starting or knock them offline. Freezing temperatures and precipitation can impact fuel supplies and knock down transmission lines. Scenarios like these may require implementing emergency procedures.

Conservative Operations: Provides an early indication that system conditions may require emergency procedures or conservative operations. In the declaration, MISO asks members to review outage plans and determine which planned maintenance or testing can be postponed. The goal of the declaration is to defer, delay or recall any non-essential maintenance.

Current emergency operating plans include issuing any of the following notifications:

Capacity Advisory: Used for situational awareness. The message informs MISO members that, based on projected system conditions and capacity levels, there may be a need in the coming days to bring additional units on-line. Members are instructed to prepare for this possibility.

Maximum Generation Alert: Tells members that electricity supply is tight and system conditions may require emergency actions.

Maximum Generation Warning: Indicates operating reserve requirements may not be met in the near future without taking actions. MISO is directing members to prepare for a possible maximum generation event. When issued, MISO may direct utilities to issue public appeals to conserve electricity.

Maximum Generation Event: This notification includes several steps that include directing members to turn on all available emergency generation, directing members to implement procedures designed to reduce energy demand,  purchasing emergency energy from our neighbors (if available), and, as a last resort, interrupting power to consumers (known as shedding load).

NOTE: Load shed is always a last resort decision designed to protect the bulk electric system from collapsing and creating wide-spread blackouts. MISO's responsibility is to identify the area where the electricity needs to be interrupted and the amount of electricity that needs to be cut. The utilities in charge of the area(s) (Local Balancing Authorities) are responsible for individual load shed programs which take into account critical load identification.  

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