Reliability Assurance 

Maintaining and managing reliability is MISO’s most important job. As the region’s Balancing Authority, MISO requires solid partnerships with transmission operators and Local Balancing Authorities. We foster these partnerships through open communication and a shared understanding of the policies, procedures and tools that support regional reliability.


Tools for System Intelligence

Superior tools and practices as well as our market-based platform let us serve load reliably and efficiently. Our tools continue to produce greater system efficiencies, bringing tangible value to our members and the customers they serve. Learn more about MISO’s Value Proposition.

State Estimator and Contingency Analysis

MISO's State Estimator and Contingency Analysis tools are the foundation for reliability and market operations. With these tools, our reliability coordinators see actual flows, voltages against limits, breaker changes and alarms.

Solving every 60 seconds or less, our State Estimator processes more than 249,000 real-time measurements, giving  our reliability coordinators a continuous assessment of the system including all flows, voltages, and angles.

Our real-time Contingency Analysis runs more than 11,500 “what-if” scenarios every four minutes. Such high-solution frequency gives MISO system operators and engineers the information they need to reliably operate the system and feed system status information to the energy markets.

Other Reliability Tools

Many other tools supplement the information system operators need to reliably operate the system, including:

  • Alarming tools ping operators when discrepancies occur with respect to voltage v. limits or flows v. limits. Alarming tools include MISO’s Topology processor, which interprets alarms and provides reliability coordinators with up-to-the-second information on topology and line outage distribution factors. 
  • Supplemental tools add to operators’ knowledge of real-time conditions and provide back-up monitoring capabilities in case the primary monitoring tools are temporarily unavailable.
  • Congestion management tools, such as the Unit Dispatch System, Constraint Logger and Interchange Distribution Calculator, provide important information to help operators manage and head off potential chokepoints or constraints on the system.
  • Five-minute dispatch provides the most economic solution  to meet load demand and maintain flows within appropriate limits. It is more precise and faster than using Transmission Loading Relief procedures to manage congestion. The Independent Market Monitor reports MISO reduced curtailed megawatt hours by 85 percent since the market began in 2005. Learn more about the Independent Market Monitor.
  • Communications tools include the Reliability Coordinator Information System (RCIS), the MISO Communications System (MCS) and extensive voice communications to further our system knowledge and situational awareness.

Visualizing Reliability

Our real-time overview displays allow system operators to zoom in on all facilities 230 kV and above as well as selected underlying facilities 100 kV and above. This big picture of the MISO transmission system and surrounding systems display real-time megawatt and reactive values - essential visual elements for system operations.



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