MISO Asks FERC to Make Large-Load Ride-Through Mandatory

MISO filed a proposed large-load interconnection reliability framework with FERC on 28 August 2026, and it converts what has been a commercial negotiation into an engineering specification with a compliance date attached.

The rules would apply to loads above 50 MW, with a distinct category for computational load — defined as large loads drawing at least 25 MW from IT equipment. Four families of requirement follow: visibility, meaning facility data and forecasts; phasor measurement unit monitoring for computational loads; ramp-rate limits; and ride-through performance during voltage and frequency disturbances. MISO proposed an effective date of 4 December 2026 and said further related filings would follow by 16 November.

The justification is written in the language of power electronics rather than of contracts. MISO argued that computational loads may exhibit rapid and coordinated changes in demand, significant power-electronic behaviour, and disturbance responses distinct from conventional industrial load. A data hall that drops tens of megawatts in milliseconds because a training job finished is a different object from a rolling mill, and the grid operator would like it instrumented accordingly.

The PMU requirement is the part with the clearest engineering consequence. Phasor measurement means sub-second, time-synchronised telemetry streaming off the site — not a monthly interval meter read. That is a synchrophasor-class installation with a disciplined time reference behind it, and for a facility that has never had to prove its dynamic behaviour to anybody, it is a new build rather than a configuration change.

The filing responds to FERC show-cause orders issued in June 2026, which directed grid operators to establish data-centre interconnection rules. ERCOT and PJM have filed broadly similar proposals, so the template is spreading rather than staying regional. MISO operates across fifteen US states and the Canadian province of Manitoba.

For anyone planning a 50 MW-plus load in that footprint, the useful reading of this is that the interconnection conversation now has a technical specification and a deadline, and both are being written while the projects are still on paper.