Final blackout report recommends installing protectors in all substations and making operational adjustments

An incorrect manual maneuver of the 138 kV San Pedro de Macorís (SPM) – Cumayasa line field disconnector was the cause of the blackout recorded on November 11th, which caused the total interruption of the electrical service in the country, according to the final report issued by the Coordinating Body of the National Interconnected Electrical System (OC-SENI). The OC-SENI highlighted that the report not only identifies the detailed sequence of the event, but also presents the recommendations and corrective actions that will allow strengthening the operation of the national electric system. These measures include continuing the installation of protections in double-bus substations throughout the country, operational adjustments to take advantage of new technologies in thermal and renewable generators, integration of battery storage systems for auxiliary services and autonomous start-up, review and adjustment of protection and automatic disconnection scheme actuation times, as well as the verification of high-frequency and auxiliary service criteria in several generation plants. The report explains that an initial event occurred associated with work to repair a detachment of an insulator that supports a cable of the 138,000-volt (138 kV) transmission line that connects the San Pedro de Macorís substation, which caused an incorrect manual maneuver of the 138 kV San Pedro de Macorís (SPM) – Cumayasa line field sectioner. "During this operation, the disconnector was opened under load, which caused a three-phase short circuit in the 138 kV San Pedro de Macorís (SPM) substation. According to the information received, the field operator of the 138 kV SPM substation had to open the disconnectors of the 138 kV SPM - Coastal line field, which was previously de-energized by the energy control center (CCE) of ETED," the report describes. The OC-SENI highlighted that the investigation was carried out by a multi-sectoral team of specialist technicians and concluded in a timely manner, within the same month in which the incident occurred. This level of speed contrasts with experiences from other countries, such as Spain and Chile, where investigations of similar events have taken up to five months to be presented. The prompt delivery of the report reflects the technical capacity, methodological rigor, and the Coordinating Body's commitment to transparency and the continuous improvement of the SENI's operation.