The increasing penetration of renewable energy sources (RES), particularly wind and solar power, introduces significant challenges to power system stability, especially regarding frequency control.

In Portugal, the transmission system operator (REN) launched in January 2025 a pilot project aimed at enabling the provision of Frequency Containment Reserve (FCR) services by renewable generation and storage technologies. This initiative, framed under the Portuguese Network Operation Regulation (ROR, 2023), and approved by the Portuguese national regulatory authority (ERSE), supports the definition of associated technical and regulatory requirements.

The FCR pilot project focuses on the validation of technical requirements for FCR provision, including control performance, compliance monitoring, detection of non-delivery events, and the establishment of verification and auditing methodologies. Particular emphasis is given to the integration of RES, which require plant control strategies to deliver proportional and automatic active power response to frequency deviations.

To complement the regulatory and conceptual framework, field tests were conducted on a wind farm connected to the Portuguese transmission system, owned by FINERGE and equipped with ENERCON wind energy converter technology. These tests involved extensive monitoring of the FCR control performance across multiple activation periods, with high-resolution SCADA data used to assess the relationship between frequency deviations and active power response.

The results of these field tests show that the FCR control was generally compliant with the specified requirements, demonstrating the technical capability of wind farms to contribute to frequency regulation, although situations with low or insufficient wind availability led to reduced controllability.

Overall, the FCR pilot project and associated field tests confirm the feasibility of wind-based FCR provision while identifying some challenges related to resource variability, control robustness, and compliance criteria. These findings will provide valuable input for the design of a robust and practical FCR market framework in Portugal, supporting the broader integration of renewable energy into ancillary services and contributing to grid stability in a low-carbon energy system.