alt Hacker NewsThe water-hammer effect, or in this case electron-hammer effect, is why you don't reboot every Windows server in the data center at exactly 2am, to stagger the load shift over time. Surprised that the power guys didn't realize that switching a presumably multi-hundred-MW load in and out at the top of each minute would cause a problem.
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It seems more like one or multiple suppliers of battery systems not taking into account that the decentralized deployments of their system could have that effect. If it's not regulated and an open market, this was bound to happen sooner or later.
In computer/systems/distributed engineering this is called request smoothing or traffic shaping, and it's implemented by adding jitter, which is a random time offset/pad added to the interval.
The funny thing is, modern electrical codes already account for this phenomenon. In order to implement Net Metering (selling your power to the grid), modern standards implement two kinds of jitter:
- Sandia Frequency Shift: a minute shift in the power frequency generated by inverters. If the grid is connected, this is effectively eliminated; if the inverter is disconnected from the grid, it detects the frequency has shifted and disconnects the inverter from the grid.
- Slip-Mode Frequency Shift: basically the same thing, but phase shift (which I don't understand).
Both of these are used for anti-islanding (don't create an island of power). When the inverter detects it's isolated and stops outputting current, it then has to check every 5 minutes, with jitter, for whether the grid is restored or not. It has to add random jitter, because otherwise all the mini battery/solar installs will come online at the same time and swamp the grid, causing another outage.
power guys got surprised as rest of the grid load is human randomised and even huge factories will come on one chonk at a time, vs miilisecond co ordinated load switching at scale, with batteries as the load of the initial surge into even fully charged batteries can be almost infinite, and the whole calculation around grid scale turbines is that they run at very precise rpm's for stability and longevity, but worse, and a big fail, as battery storage is supposed to help with that, not be the problem. bet it gets fixed realy fast as those grid guys definitly get listened to.
Sounds like they've been set up as cron tasks. I've always been unhappy with the 1 minute granularity of cron tasks. Only thing I could come up with was putting a sleep(random()) type of line to avoid a thundering herd type of issue.