The four "R" words of an advanced grid: Reliability and resiliency are not enough
By: SGN Staff
Quick Take: Doug Houseman is one of the world's pre-eminent power engineers and the Vice President of Innovation and Technology at EnerNex. He has produced advanced grid designs for the U.S., China and elsewhere. He says that the two familiar "R" words, reliability and resiliency, are not good enough. In fact, we need know four "R" words, and we need to know when to use them. Read on, then leave your comments using the form at the bottom. - By Jesse Berst
By Doug Houseman
There has been a lot of discussion on how to make the grid more reliable and resilient. Many people use these terms interchangeably. When engineers do, we start to run into trouble. There are four â€œRâ€ words that are critical to the discussion and they are applied at different times and require different thinking.
Start with the current buzzword that seems to be ringing through the political crowd: resiliency. Everyone wants the grid to be more resilient. But what is resilience? The dictionary says that resilient is the ability to bounce back, in military discussions resilience is about designed in redundancy so that any single component failure, does not disable the system. In the electric grid, resilience typically comes from feeding locations via multiple independent paths, this has worked well for Manhattan which measures raw outage for most customers in single seconds per year. Undergrounding has been touted as the right way to increase resilience, but in reality if there is one path to a location if something fails in that path, then the locations beyond that component will see a power failure.
Reliability is a long time industry term that looks at how much of the time the grid delivers power. IEEE created a number of measures for reliability, including same that have found their way into regulatory discussions, such as SAIDI and CAIDI. Influencing reliability can be done with the choice of components, the location of components, and the maintenance of components. Reliability is something that is created prior to a disaster and is the second leg of keeping the lights on.