Islanding and Large Loads: How Islanding is Changing Autonomous Energy
(sources, NERC regs and guidelines, SMPNet, Mar 2024, experential knowledge)
ISLANDING refers to a situation in power grids where a part of the grid (i.e., power island) gets separated from the main power network. If you are not connected to the grid at all, this does not happen, but the issue is not trivial, see below for whether you are regulated by NERC. STARLINK could render much of this irrelevant, but presumably that will be more long-dated than developers want to wait.
If you are co-located, you will be connected to the grid and must deal with this issue. The easiest way to island is to open your switches so current cannot flow through. (If done deliberately this might be because you observe in the control room that an adjacent ERO is having major difficulties, such as blackouts or frequency drops, that you cannot help out on, or it may be because transmission gets cut because there is inadequate transfer capacity.) But you have to figure out how to keep your own operations running smoothly, and you have to figure out how to reconnect; you can't stay unconnected forever.
(AI ISSUE. DISCONNECTION OF DISTRIBUTION BLOCKS OF ENERGY IS A NEWER ISSUE, SO SOME TERMS ARE NOT STANDARDIZED. Several AI articles confuse Islanding with Isolation, which is a transformer function term—more in later post; the AI articles indicate that Isolation is lawful vis a vis NERC and Islanding is unplanned or lacking in procedures for handling and is thus nonconforming.)
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ISLANDING, PLANNED AND UNPLANNED. This comment deals with large loads such as data centers and the process of islanding, planned and unplanned. It is easier to deal with islanding involving a large interruptible load, with or without batteries, than a base load such as a data center unless there is excess capacity and adequate BESS to lean on.
Protocols and Plans for operation converting to an island, operating during an island, and reconnecting are still needed.
NERC has primary responsibility for Reliability on the grid, and generators and transmission owners must comply with NERC Standards and Guidelines. Load, especially volatile load—not planned regular fluctuations) can often affect reliability. Actions must be taken to protect not only the load, but also the continued existence and operation of the transmission wires, transmission and distribution equipment, batteries, and generation.
NERC is inching toward taking jurisdiction over large loads even behind the fence, but no guideline or standard has been adopted. As mentioned, co-location loads are already tied to the grid.
NERC’S LARGE LOADS TASK FORCE (LLTF). To begin understanding large loads and identify effective pathways for their integration, NERC’s Reliability and Security Technical Committee (RSTC) established a Large Loads Task Force (LLTF) in August 2024.
There is a time mismatch. The NERC task force has not finished, and the transmission capacity and interconnections are not all ready, but the demand for the large loads is ready to go and will not wait.
INTENTIONAL DISCONNECT PERMITTED? A crucial question is whether now large loads such as data centers can intentionally disconnect themselves from the grid (even with signed interconnection obligations).
The answer is YES and is documented in NERC’s Large Loads Frequently Asked Questions, May 2025:
“VOLTAGE RIDE-THROUGH. Currently, there are no specific voltage ride-through Reliability Standards for large loads. Large loads, specifically data centers, frequently house a multitude of sensitive electronics that require ideal electrical conditions. If poor electrical conditions exist (like low voltage), large loads can disconnect from the grid to protect their equipment from damage.”
(If you are tied to the grid, there is an issue of whether you may just decide you do not want to be on the grid on a given day, i.e. you do not observe low voltage; you just do not want to mess with multiple markets, costing and hedging LMP which you do not get to avoid with bilateral contracts, and other non-electrical engineering complexities and grid idiosyncrasies. I do not think we all can have a voluntary grid; the grid by its nature is socialized. You signed a mutual agreement. But NERC change could come if we got a more modern 21st century grid.)
RELIABILITY GUIDELINE. A reliability guideline on Risk Mitigation for Emerging Large Loads is also included in the LLTF Work Plan. Progress on these upcoming documents can be found on NERC’s website. Additionally, the NERC LLTF hosts monthly meetings for industry experts to present the latest work on large load integration to the grid.
IS A BEHIND THE FENCE FACILITY SUBJECT TO NERC REGS? A fence doesn't automatically exempt a generator from NERC. NERC Regulations apply as to size—large renewable projects 20MVA, 60kV, and interconnection point at 100kV, suffice to require a generator to register as a GO/GOP and to comply with applicable NERC Standards.
NERC requires each system, control area, pool, and Region to have procedures to deal with operating emergencies:
** Agreements for emergency assistance from neighboring systems;
** Procedures for system operators
** Authority to shed adequate load (and to determine blocks of load to be shedded) to restore generation/load balance to prevent undershedding;
** Procedures for system restoration
** As a failsafe, each area is required to install automatic underfrequency load shedding (protective relays detect a low frequency condition and automatically actuate the disconnection of blocks of load to arrest the decline in frequency and restore 60Hz operations