Eagle Pass is a community across the US/Mexico border with Piedras Negras, Coahula. Eagle Pass load is served by two 138 kV transmission lines and due to load growth the area is prone to voltage instability following transmission contingencies during peak load periods, reducing the reliability of power delivery on the U.S. side of the border.
During emergencies, power for the Eagle Pass distribution network can be brought in from Mexico over a 138 kV line to the CFE grid, but making the connection involves a „block over“ switching operation at the substation, which briefly interrupts power delivery to customer loads.
To mitigate possible voltage instability and at the same time allow power exchange in either direction between the U.S. and Mexico without first having to disrupt service to distribution system customers, an Hitachi Energy Back-to-Back Light installation rated at 36 MVA at 138 kV has been installed and commissioned in the Eagle Pass substation owned by Central Power and Light Company (CPL), a subsidiary of American Electric Power Company (AEP). The project was executed jointly by EPRI, AEP, and Hitachi Energy.