El Salvador power plant

Verkís services was detail design, tender documents, procurement, commissioning: mechanical and electrical equipment, control and protection.

The plant utilizes 300 kg/s of 180°C geothermal fluid for electrical generation. The brine is extracted from 4 wells, 2.000 to 2.500 m deep and is led through two mist separators. The two fluids coming from the mist separators are not mixed.

The brine is led through evaporators, consisting of two pre-heaters and a re-boiler, and exchanges heat with the plant’s working fluid. Isopentane is used as the working fluid in the Organic Ranking Cycle. It is circulated in a closed loop and is led through the radial inflow turbine to generate electricity. The fluid is then regenerated at the condenser where cooling water is circulated through a wet cooling tower of the counter flow type.

The 13,8kV generator is of the air cooled turbo type, installed with air-to-water heat exchangers. The exciter system is of the brushless design. The generator is connected to a 13,8kV switchgear, which is metal-clad, compartmented and withdrawable. The switchgear is connected to a power transformer, where the second winding is connected to a 115 kV high voltage line through a disconnecting switch to the existing plant substation. The 480V distribution switchgear consists of compartmented withdrawable feeders. The 120V direct current system is redundant.

The control system comprises of one PLC, installed with hot standby CPU units. The control systems are connected to two servers, one located in the binary plant and the other in another existing plant and a connection to a dispatch centre is installed. The protection relay system is of the double digital type, provided with data communication links.