Power grid · Frequency
Grid frequency wobbles slightly around its nominal value all the time. When a plant trips, it jolts — and "how much the compressor has to speak" gives the event away, with no detector programmed.
Grid frequency — 50 Hz in Europe, 60 Hz in Brazil — isn't fixed: it wobbles slightly all the time, following the balance between what's consumed and what's generated. If load suddenly rises (or a plant drops out), frequency falls; if there's surplus generation, it rises. That's why the system operator chases this balance second by second. And there's a norm defining the acceptable band (e.g., staying within ±0.2 Hz of nominal in normal operation) — so the tolerated error is already written in a document.
TUBE compresses data with a simple rule: instead of storing every measurement, it draws a "tube" of tolerance around the signal and stays quiet as long as the value doesn't leave the tube — whoever reconstructs it later knows it was around there, within the guaranteed margin. That silence is the deadband. Only when the signal breaks out of the tube does it emit a new point.
In a healthy grid, frequency drifts slowly inside the norm's band — so the compressor barely speaks. It's the perfect deadband case: 94.7% silence across six months.
We ran the 6 months of 2026 (January to June) of the British system frequency, every second — 15.6 million measurements. While the grid stays in band, the tube holds. But on every excursion (a generator trip, a load step) the frequency jolts out of band and the tube breaks — the emission rate jumps. In the chart below, each peak is a real event of the semester; the largest took the frequency to 49.6 Hz.
Nobody programmed a grid-event detector. The compressor was just trying to save space. But "how much it needs to speak" is, in practice, a measure of surprise: grid in balance = silence; frequency jolt = chatter. So event detection comes out as a byproduct of compression — with a rare advantage: because the norm defines the band (the ε), the alarm is certified, not a guess. It's the same argument as the submarine cable that became a seismograph, now on the power grid — and the direct sibling of our synchrophasor (PMU) note, where the phasor error (TVE) is already the norm's ε.
We measured on the British system (50 Hz), because it's the cleanest open 1-second public series. In Brazil the grid is 60 Hz and the behavior is the same — the physics of the argument doesn't depend on the nominal value; what matters is "signal in band + event = surprise". High-resolution raw 60 Hz data is still barely open here. And unlike partial discharge (a noisy signal where the raw surprise doesn't isolate the event), frequency is the clean case: slow signal, norm band, crisp event.