What is the ONS's surplus management plan? Could it leave consumers without power?

The Energy Surplus Management Plan returned to the radar of the electricity sector last weekend, following the possibility of a new activation to balance generation and consumption in the SIN (National Interconnected System).

This measure could lead, for the third time this year, to a reduction in generation from power plants connected to distribution networks, if the resources available under the direct coordination of the ONS (National System Operator) are not sufficient to control the excess energy.

But what does activating this plan mean in practice?

The Surplus Management Plan is a preventive measure used in situations where, even after reducing generation under the responsibility of the ONS (National System Operator), it is still necessary to decrease the production of energy connected to distributors in order to balance generation and consumption.

This scenario is more likely to occur during periods of low load, such as weekends and holidays, when electricity consumption tends to be lower.

Activation does not mean lack of power.

Despite involving generation cuts, activating the plan does not mean that regions or consumers will be left without power supply. In practice, the problem faced at these times is the opposite: more energy is being produced than consumed in the system.

Therefore, some generation needs to be reduced to preserve the balance between supply and demand and ensure the stability of the National Interconnected System (SIN). In other words, the cut occurs in the production of certain power plants, and not in the supply of electricity to consumers.

The measure aims precisely to prevent excessive generation from causing imbalances that could compromise the safety of the electrical system's operation.

Understand how the Surplus Management Plan works.

The Surplus Management Plan establishes a sequence of measures to deal with periods when available energy generation exceeds the load on the electrical system.

Before any intervention in the distribution networks, the ONS (National System Operator) utilizes the resources available in centralized generation (CG), including reducing the production of large solar and wind power plants connected to the transmission system.

Only when these measures are insufficient to restore the balance between generation and consumption does the plan foresee actions involving the distributors.

At this stage, the utility companies are notified in advance so that they are prepared to reduce, if necessary, the generation of projects connected to their networks.

Among the projects that may be affected are the so-called Type 3 Power Plants, facilities that are not directly dispatched by the ONS (National System Operator) and whose generation reduction depends on the actions of the distributors.

The activation, therefore, does not occur by surprise. The ONS monitors the SIN 24 hours a day and tracks generation and consumption conditions, while the need to advance the measures depends on the scenario verified during the operation.

That's what happened last weekend. On Friday (28), ONS classified the probability of activating the plan on Sunday (30) as “medium”, leaving distributors on notice for a possible need to reduce generation.

Therefore, the Surplus Management Plan did not need to be activated on Sunday, unlike what happened on two other occasions this year, on June 7 and August 23, when there was a reduction in generation from projects connected to distribution networks.

After warning distributors, ONS did not implement generation cuts over the weekend.

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