RusHydro’s Sayano-Shushenskaya project – the utility’s largest hydroelectric power plant – has increased its maximum capacity output by 250MW to 5100MW.

The capacity expansion was approved by the System Operator after a second high-voltage transmission line connecting the power systems of the Khakassia and Krasnoyark region has been commissioned.

The maximum capacity output from the station was previously raised from 4400 to 4850MW following the modernization of automatic reliability systems installed at the station. As a result, in 2015, Sayano-Shushenskaya released 700MW of ‘locked’ capacity, which is comparable to a single hydropower unit of the power plant of 640MW.

Until 2015, the maximum plant’s available capacity was limited to just 4400MW of the total 6400MW installed, caused by lack of interconnection capacity in the region RusHydro said. This resulted in 2000MW of ‘locked’ capacity and output restrictions during some high-water years.

Sayano-Shushenskaya has undergone a major refurbishment following a fatal incident at the plant in August 2009 where the turbine room and power equipment were flooded, the projects 10 hydropower units were damaged, and 75 people were killed.

The project to rebuild the plant was completed in three stages. The first, in 2010, involved restoring the four least damaged turbines and placing them back in operation. Over 2011-2013, five newly manufactured hydropower units were launched in the second stage.

In the third and final stage, carried out over 2013-2014, the four previously restored hydropower units were replaced with the new ones, and the last unit – No.2 – was commissioned.