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Irish scientists comment on power outages across the Iberian Peninsula.
Dr Paul Cuffe, Assistant Professor, School of Electrical and Electronic Engineering, University College Dublin (UCD), said:
“Electricity grids are tightly-coupled physical systems with an innate fragility. Despite the best efforts of grid operators, the risk of a sudden, widespread blackouts can never be fully eliminated.
For instance, system operators must continually ensure that the amount of power being fed into the grid by generators precisely matches the withdrawal of power by electrical loads. Maintaining this balance can be very difficult if a major power station fails suddenly. Likewise, overhead power lines can also fail abruptly sometimes; when this happens, the massive power flows they carry transfers itself instantaneously to other lines elsewhere in the grid, potentially overloading them. This is why power grids are “brittle”: the failure of one component can trigger a domino effect, catalysing problems elsewhere that cascade through the grid, sometimes causing widespread power outages.
Systems operators are rightly conservative and manage this fragility by operating their grids within generous safety margins. A key principle is the (N-1) criterion, which stipulates that a power network should always be able to survive the loss of any one of its components. This security criterion means that the sudden loss of a generator, or abrupt outage of a line, should not imperil the wider health of the network. However, sometimes a “perfect storm” arises, and system operators are afflicted by distinct technical problems in quick succession, and major blackouts can then result.
Large parts of Spain and Portugal have lost their supply of electricity today. In Spain, it appears that consumption of electricity dropped very rapidly from around 25 GW to just 10 GW in the course of mere seconds. This type of wide area blackout is the “nightmare scenario” for power grid operators, whose guiding ethos is the avoidance of such failures.
The Spanish and Portuguese systems operators will be implementing their “black start” power restoration plans. These plans are carefully compiled, to provide a step-by-step sequence of steps to get all the generators in your country back online and producing again. This is difficult; it actually requires electricity to bring a power station online to a point where it can produce electricity of its own. So system operators need to be able to “pull themselves up by their bootstraps”, rekindling the whole grid from even just one small diesel generator.
These plans are carefully compiled, checked and rehearsed regularly. The threat of a major blackout is the lurking fear of all grid operators, so they proactively anticipate these outages and have contingency plans they can activate to resolve them as rapidly as possible.”
Declarations of interest:
No reply to our request for DOIs was received.