The ONS (National Electric System Operator) again registered this Sunday (28) high levels of restrictions on renewable generation in the SIN (National Interconnected System), known by the jargon “curtailment”. According to the Preliminary Operation Diary (IPDO), the Northeast had a peak cut of 14,278 MW throughout the daykeeping the region as the main focus of the operational limitations faced by the Brazilian system.
In energy equivalences, the amount is equivalent to the installed capacity of Itaipu Binacionalthe third largest hydroelectric plant on the planet. The restrictions occurred throughout practically the entire day — between 0 am and 5:49 pm and again between 6:46 pm and 11:59 pm — and were caused by the control of regional inequalities in normal operating instructions, in addition to interventions related to frequency control of the electrical system.
The restricted volume in the Northeast easily exceeds that observed in the other submarkets. In the Southeast/Central-West, the maximum restriction reached 645 MW, between 6:25 am and 4:45 pm, exclusively due to frequency control. In the South, the maximum value was 203 MW, between 6:26 am and 3:47 pm, also for the same reason. In the North, the ONS only reported that there was a limitation between 6:25 am and 3:46 pm, without detailing a maximum value, also due to the need for frequency control.
Despite the restrictions, the Northeast continued to be the main hub for renewable generation in the country. In the daily energy balance, the region produced 13,365 average MW of wind energy and 2,785 average MW of solar generation, accounting for the largest share of national renewable production. The submarket’s load was 11,994 average MW, which reinforces the need to flow excess energy to other regions of the country.
. The restriction occurs when wind and solar farms need to reduce or interrupt their generation as determined by the ONS, even when wind or sun is available, to preserve electrical safety or due to limitations in the transmission network.
Cuts occur for three reasons: the lack of transmission infrastructure, such as damaged or delayed lines, in which the generator may be reimbursed as it is not responsible for the problem; when transmission lines reach capacity limits and energy cannot be transferred; and excess supply in relation to demand. In the last two cases, there is no right to compensation.
