The post Are 1-in-10-Year Events Really 1-in-10-Year Events Anymore? appeared first on POWER Magazine.

When evaluating resource adequacy requirements, many power companies and grid operators have used a methodology that originated more than 70 years ago. This probabilistic reliability approach has generally performed adequately through the years. It has generally evaluated loss-of-load events occurring at frequencies of one-day-in-10-years (1-in-10) to be acceptable in terms of system reliability.

However, it’s not without risk, as incidents in Texas, California, and other parts of the country and world have demonstrated in recent history. In light of these events, it’s worth asking: have risks changed? It could be that the method used to evaluate what constitutes a 1-in-10 event is no longer sound.

“When you have 1-in-a-5 or 1-in-a-10-year event that’s happening every year, most likely those are not 1-in-a-10 or 1-in-100-year events,” Electric Power Research Institute (EPRI) CEO Arshad Mansoor said as a guest on The POWER Podcast.

“Really, what we need to go is beyond that.…

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