“Texas limits itself from “buying more from other providers through the grid” because they are their own self-synchronized AC island, not synched up to either the Eastern or Western North American grids, or to the Mexican grid for that matter.”
Yes we have three HVDC and one VFT with about 1000MW total bidirectional power flows.
There is a project to link a major power hub aka Hub North in Garland Texas via a 3000MW HVDC link to Mississippi and thus the Southern interconnection (SERC)
There was a Tres Amegas project for the panhandle area where the three North American grids touch with ERCOT not being in phase with the other two which are in phase. So it was to be a triple back to back HVDC-HVDC-HVDC link up 13,000 megawatts worth. Texas alone is 85,000MW in August peak and avg around 45,000MW baseloads so even with Tres Amegas and the MS link I would not have helped much when we lost 38,000MW of thermal generation off line during Uri, plus two of four of the nuclear reactors cooling system froze out for days at a time.
Again we came within 4 min of a total grid failure and a black start event which would take up to a month to bring the grid fully online. It takes special turbines to black start they need to be externally exciting and also have a stable frequency source like an atomic clock or GPS PNT source. You need black start diesels to power the 1500MW exciting generator which then excites the electromagnets in the gas turbine generator it’s expensive specific equipment only used for one thing. Texas keeps our hydropower specifically because water turbines are black start capable.
Turns out large grid scale solar inverters the modern kind can not only island mode totally free from grid phase relationships they can also push reactive and active power to a black grid setting up the standing wave phase angles needed to use not self exciting synchronous generators online, variable speed wind turbines using the same kind of grid forming inverters. Most small inverters are grid following types or voltage sensing is another name. Grid forming inverters are exactly as they sound they push active and reactive power outwards not consume it they also can set phase relationships as virtual inertia. Of course synchronous wind turbines just like gas synchronous turbines carry rotational inertia in their spinning masses they need a phase relationship to a standing grid wave to function so they cannot black start at all.
Yes I am a power industry professional , oil & gas as well. I started as an engineer before moving into pure sciences.
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*power the 1500HP exciting generator.
It should be pointed out that synchronous West Texas wind turbines were the grids spinning inertia and phase angles source when the gas grid and turbines both cascaded into failure.
Those turbines and grid forming inverters are what saved the ERCOT grid from total collapse and months of outages during a black start event. Again the link to the report the legislature used to write laws to prevent it happening again is above. Note that solar and wind have grown by large amounts since the report and more new inverter are....Yeah grid forming inverters because they are a very useful back up and fail safe.