Home > Research Areas > Real-Time Grid Reliability Management > Key Accomplishments > CERTS ACE-Frequency Real-Time Monitoring System

Real-Time Reliability Management Tools

CERTS ACE-Frequency Real-Time Monitoring System

Screenshot of ACE-Frequency Real-Time Monitoring System showing the Control Area Map (the entire United States) with current ACE and ACE/L10 indicated. Screenshot of ACE-Frequency Real-Time Monitoring System showing Selected Control Zones on the Current Control Area Map (the entire United States) with last minute ACE and ACE/L10 indicated.

Figure. Visual displays allow NERC Reliability Coordinators to pinpoint interconnections, reliability regions, or control areas that are over-generating (green) or under-generating (red) in real time. Tracking displays record and present the information over time to enable corrective actions for persistent excursions from agreed upon limits.

Reliability Coordinators throughout the nation are now using a new real-time monitoring tool developed by CERTS for the North American Electric Reliability Council (NERC). The CERTS Area Control Error (ACE) Frequency Real-Time Monitoring System allows Reliability Coordinators to monitor compliance with NERC rules designed to ensure the reliable supply of electricity.

Until this tool was introduced, months of data analysis were required to determine the causes of rule violations that threatened reliability, so corrective action was not possible until it was too late. Now, however, the ACE Frequency Real-Time Monitoring System immediately alerts Reliability Coordinators to conditions that threaten reliability so that there is time to work with out-of-compliance control areas to correct impending problems in real time, reducing the chances of unplanned blackouts.

The ACE tool uses data visualization techniques to assess compliance with NERC reliability rules for the 143 control areas in North America. The tool relies on data generated every four seconds by all control areas and creates a real-time visual display of the entire power grid. This display immediately alerts NERC Reliability Coordinators to emerging frequency abnormalities within an interconnection and can pinpoint the control areas causing the violations. Armed with this information, coordinators can initiate corrective actions within minutes to prevent further degradation of system reliability.

CERTS released the tool to all 23 NERC Reliability Coordinators and selected control areas in the fall of 2002. Four special training sessions were conducted in each region of the country in November and December 2002, hosted by the Midwest ISO, the New York ISO (NYISO), Southern Company, and CAISO.


Carlos Martinez
Electric Power Group, LLC
(626) 685-2015