MISO said it experienced a “complete loss of monitoring or control capability” at its control center last week, setting off short-lived energy imbalances.

According to the grid operator, the March 1 incident lasted about 41 minutes. It said it was administering routine quarterly maintenance on its energy management system (EMS) at midnight to update modeling. However, “issues with the update” sent incorrect dispatch signals to generation through the RTO’s automatic generation control tool.

MISO said the glitch led to an imbalance in its balancing authority and a Balancing Authority ACE Limit (BAAL) event. It said its area control error (ACE) reached as high as 2,000 MW, resulting in a 17-minute BAAL event.

The ACE then swung as low as -4,285 MW, resulting in a second BAAL event for 11 minutes, MISO said. It said it used “backup tools and processes” to regain the control room’s monitoring and control capability.

The grid operator said it reported the disturbance to the Department of Energy through the agency’s electric emergency incident and disturbance report (form DOE-417), which is used to collect information on incidents and emergencies. 

MISO said its backup plan included reverting temporarily to its earlier December model. It said the model worked as intended.

“We were able to address the incident in less than 15 minutes and move to our new model within a couple of hours, spokesperson Brandon Morris said in an emailed statement to RTO Insider. “We are reviewing the situation and will improve the processes under our new model manager and EMS systems.”

MISO is working to deploy a new EMS and a one-stop model manager that will serve as a single record for maintaining members’ modeling information. The RTO said it experiences redundant data entry and review because it lacks a unified modeling process for reliability, markets and planning. (See MISO Pivots to Models, Market Engines in New Platform Replacement.)