The Iberian Blackouts - What We Know so Far
We are waiting to learn what caused the Iberian blackouts. A full investigation may take many months, meaning we don't know the precise chain of events that took down the Iberian power grid, and we shouldn’t speculate on the causes until we have the data.
Nevertheless, this tragedy has drawn attention to the challenge of maintaining frequency stability as electricity systems decarbonise. The frequency of an AC electricity system must remain within 49.8-50.2 Hz under normal conditions, and never outside 49-51.5 Hz, even during a disturbance, in continental Europe. Frequency is a product of the intersection of generation (supply) and load (demand): if generation exceeds load, the frequency rises; if load exceeds generation, the frequency falls.
Traditional synchronous generators – coal, gas, biomass, and large hydro - are able to adjust their output in real time to ensure that generation matches load, keeping the frequency stable. Meanwhile, the inertia of the massive turbines in these generators resists changes in frequency, smoothing out perturbations and slowing frequency deviations, allowing generators time to adjust their output and respond.
By contrast, solar and wind deliver low-cost, zero-carbon energy, but they cannot easily adjust their output and have little mechanical inertia to stabilise the system. As such, the electricity grid of the past cannot support the zero-carbon future where the bulk of generation will come from variable renewable energy (VRE). Not only will the future energy system be based on distributed resources, but the basis of system stability will change. New technologies must supply the system stability services that fossil fuel turbines once provided.
ENODA delivers that capability today. Enoda PRIME® Exchangers replace traditional, transformer-based distribution substations. They stabilise and de-constrain the local distribution network, unlocking headroom for distributed energy resources. The Enoda ENSEMBLE™ platform coordinates Prime Exchangers so that many tiny voltage adjustments aggregate into a powerful, system-wide frequency service.
If generators can't change their output fast enough to match load, the alternative is to modulate the behaviour of the load side. Directly controlling millions of individual appliances is technically and commercially implausible, but adjusting feeder voltages – always within statutory voltage limits - achieves same effect automatically: at slightly lower voltage a resistive load (say, an oven) draws less current and heats marginally slower; at higher voltage it does the reverse.
A fleet of Prime Exchangers thus turns the distribution network itself into a fast, precise frequency-stability asset, decoupling renewable generation and system stability, and ensuring that the carbonised grid can ride through the next disturbance without lights going out.
During the Iberian blackout event, the automatic Under-Frequency Load Shedding (UFLS) scheme did trigger, cutting power to some customers, yet it could not arrest the collapse.
Why couldn't the automatic Under-Frequency Load Shedding save the day - and where could ENODA have changed the outcome?
When frequency plunged below 49.5 Hz, the Iberian UFLS scheme dutifully tripped whole feeders. Yet it shed far less net demand than planners expected, because the very same disturbance had already tripped roughly 15 GW of distribution-connected solar at midday — meaning the feeders UFLS disconnected were carrying little net load.
Prime Exchangers would have attacked the problem in two ways. Firstly, within one grid cycle they would have lowered local voltages by a few per-cent, instantly removing gigawatts of demand while holding PV in service, slowing the frequency dive so that UFLS set-points were never crossed. Secondly, had further action still been required, UFLS would then have acted on feeders whose net demand was intact, making each block shed fully effective. In short, ENODA turns UFLS from a blunt last-resort into a rarely-needed back-stop.
The blackout has created a clear expectation for change and will increase the momentum of grid modernisation. System operators and policy makers must not miss the opportunity to use this momentum to deliver a system that is fit for the future of energy.