Strengthening the electricity bond between the US and Mexico

Additional 150 megawatts to double capacity of Sharyland asynchronous HVDC interconnection between Texas and Mexico

Interconnections between countries help optimize power systems, bring energy efficiency benefits and increase power security for consumers.

The Sharyland asynchronous interconnection, located on the banks of the Rio Grande River, was the first of its kind when commissioned in 2007, to support emergency  electricity needs and commercial power exchange  between Texas and Mexico.

The 150-megawatt high-voltage direct current (HVDC) tie interconnector is designed to enable two-way electricity transfers between completely independent power grids. It also allows sharing of reserves, facilitates cross-border trading and increases the reliability of both grids. The back-to-back system has a capacity to deliver 150 megawatts (MW) of power in either direction.

In addition to the fast and precise ‘active’ and ‘reactive’ power control features integrated with HVDC technology, the interconnection is also equipped with a ‘black start’ capability, which enables the grid to be restored quickly in the event of a power outage and allows power to be used from the other end of the link. The link also has a built in ‘firewall’ functionality which prevents disturbances from spreading between the grids. It is also capable of unmanned or remote operation from a dispatch center in the ERCOT network on the US side.

ABB will now build another 150 megawatt (MW) back-to-back HVDC converter station in Mission, Texas, adjacent to the existing site and the two stations will work in parallel to provide a combined transmission capacity of up to 300 MW. This enhancement in power supply will support economic growth in the region and will strengthen the local grids on both sides. ABB will additionally deliver high-voltage equipment including power transformers and thyristor valves. The station is scheduled to go into operation in 2014.

Most of Mexico’s electricity generation comes from conventional thermal plants, mainly fuelled by natural gas. As per EIA (US Energy Information Administration) the electricity trade between the US and Mexico dates back to 1905, when private utilities in remote towns on both sides, exchanged electricity across low-voltage lines, to help each other meet demand. As the sector developed more cross-border transmission lines were constructed though relatively limited in capacity and U.S.-Mexico electricity trade has remained small.

Mexico has been a marginal net exporter of electricity to the US since 2006 and power sales from Mexico to California offset exports from Texas to Mexico in 2010. Preliminary 2012 data however indicates that Mexico has begun to import more electricity from the US and electricity sales from Mexico to the US could also increase in the mid-term, as the US Department of Energy recently issued a Presidential permit for a 230 kilovolt transmission line across the U.S.-Mexico border. When completed, this link will supply electricity from a Mexican wind farm to the California market.


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