Reliability performance is core to the utility industry. Utilities strategically design and invest in their system to maximize reliability performance—traditionally measured by System Average Interruption Frequency Index (SAIFI), System Average Interruption Duration Index (SAIDI), and/or Consumer Average Interruption Duration Index (CAIDI). These quantitative metrics largely drive utility investment decisions, shape strategic priorities, dictate regulatory approvals, and determine cost recovery. While these metrics are generally good indicators of system performance, the commonly used SAIFI/SAIDI/CAIDI indicators actually refer to “blue sky” system performance, where hurricanes and other large and impactful outage events are not counted toward these reportable performance metrics. Therefore, long-duration outages that greatly inconvenience customers are unaccounted for in this view.
In addition to reliability, the concept of grid modernization is fundamental to utility success. To keep up with changing customer and technology demands on the electric system, utilities must invest in modernizing their capability and functionality; and then provide those additional capabilities to customers and ratepayers. Grid modernizing capabilities include optimizing technologies for restoration and monitoring, as well as modifying the distribution system away from a uni-directional feed design to facilitate a bi-directional feed system—allowing the connection to distributed energy resources, electric vehicles, etc. As these modernizations are planned and executed, utilities still measure their customer and regulatory performance by their ability to reliably deliver electricity. However, reliability success depending on these metrics remains somewhat myopic when it comes to making utility investment decisions, as it still fails to measure the value of delivering power to customers when they need it most—when it’s out.
Until recently, the concept of measuring the grid based on its reliability performance and capabilities alone has been the norm. It’s evident that we’re experiencing severe weather impacts more frequently than we have in the past. The potential for outages from severe weather is compounded by additional threats facing the grid, like cyberattacks and global pandemics. Due to this, grid resiliency has become an increasingly critical topic. Resiliency—how quickly and effectively the grid can restore to normal operations after any major disruption—is the third pillar to a utility’s future success.
Gregg Edeson is PA Consulting’s utility reliability and resiliency lead. Aleka Stevens is an energy and utilities expert at PA Consulting.
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