RÍO AMOYÁ - LA ESPERANZA Hydroelectric Power Plant

Transcription

1 RÍO AMOYÁ - LA ESPERANZA Hydroelectric Power Plant The power plant is located in southern Tolima, in the municipality of Chaparral, approximately 150 km from Ibague. It has an installed capacity of 80 MW from two generating units. Its intended average energy output is 510 GWh/year. The power plant harnesses water from the Amoyá and Davis Rivers through a run-of-the-river intake system. As a result, it doesn t have a reservoir, thereby reducing its impact on the environment. In addition, it meets the requirements of the Clean Development Mechanism, affirming the plant s contribution to climate change mitigation with national and international authorities. Civil works The underground plant harnesses a flow rate of m 3 /s. The gross head is m, which is due to the forebay being located at 1,478.7 meters above sea level and the turbines at meters above sea level, with a hydraulic loss in the headrace tunnel of 20.1 m.

2 Installed capacity of 80 MW

3 1 2 The powerhouse is a room that houses two groups of generators. The room is 12.6 m wide, has a maximum height of 27 m and a length of m, with a horseshoeshaped section and straight walls. Upstream, there is an area that houses the control building, whose approximate dimensions are 12 m x 5 m, with a height of 14.6 m. The access tunnel to the powerhouse is 943 m long and has a gradient of 9.5% at the end of the tunnel. At the end of the access tunnel and before powerhouse, the transformer room has been excavated, where the transformers and GIS substation will be housed 3 The headrace tunnel has a horseshoe-shaped excavation section, an excavation diameter of 3.5 m and a flat floor. The headrace tunnel will be 8,663 m long, including the distributor branches. Prior to the underground powerhouse, the tunnel has metal reinforcement of approximately 245 m in length to control the hydraulic gradient that may develop between the upstream sector of the cavern. The headrace tunnel has a gravel trap, located upstream of the metal reinforcement. The intake is located in a rock-narrowing present immediately downstream of the confluence of the Amoyá and Davis Rivers, at an elevation of 1,484 meters. The intake consists of a damspillway that was built through the river channel. The damspillway is made of mass concrete and is 5 m high. Intake for the dam-spillway is performed through a bottom grating that is 37 m long and 2.25 m wide. Next to the rightside closure wall of the dam-spillway, passing the intake gate, is the de-gravelling tank, which has an uncontrolled orifice 0.65 m in diameter to freely evacuate the environmental flow of 1 m3/s, a second 2.0 x 2.0 m orifice controlled by a slide gate for removing gravel that enters via intake, a lateral spillway for channeling flows into the tank and intake channel, and an overflow that empties into the river. Between the intake and the sand separator, there is a squaresection intake channel that is approximately 105 m long, which is built with reinforced concrete on a bank excavated from the right abutment. At the end of the intake channel is the distribution channel, which has an overflow spillway. In order to remove the particulate matter that may affect the turbines, there is a conventional sand separator that is designed to retain sand particles greater than 0.20 mm. The sand separator also has a mesh system for the retention of floating plant material and ends in a stabilizer screen. At its downstream end, the water level in the sand separator is controlled by a spillway, which delivers water to the forebay tank that feeds the headrace tunnel. The forebay tank has an overflow spillway to ensure that flows that have not been utilized by the plant are returned to the river. The access tunnel to the powerhouse is 943 m long and has a gradient of 9.5% at the end of the tunnel. At the end of the access tunnel and before the powerhouse, the transformer room has been excavated where the transformers and GIS substation will be housed.

4 Access tunnel to powerhouse 2 Discharge tunnel Room for 115 kv substation and power transformers 1 3 Powerhouse room Headrace pipes Alternate access tunnel

5 Main generating equipment The Amoyá power plant has two vertical shaft Pelton turbines, with six jets and rated power of 40 MW at rpm. They are attached to synchronous generators with a rated power of 45.7 MVA, 13.8 kv and 14 poles. Each turbine has a 1.1 m diameter ball valve activated by single-acting hydraulic actuators. In emergencies, this valve is designed to close with flow. The synchronization process for the plant s units takes place through 13.8 kv unit circuit breakers. The energy generated is delivered through busbar ducts at a voltage of 13.8 kv to two power transformers with a rated capacity of MVA each, thus raising the voltage from 13.8 kv to 115 kv. From there, the energy travels to a compact switching substation, encapsulated in SF6, and is then transmitted outside the plant using three unipolar cables insulated with an XLPE insulating material for 115 kv, forming a three-phase circuit that has a backup cable for fault events.

6 These cables are each approximately 1.2 kilometers long and travel along the plant s access tunnel, attached to one of its side walls. Once they reach outside, they connect in a cable gantry where there is a transition, and insulated cables become bare cables, which travel along a 18.6-kilometer, 115 kv transmission line laid between the plant and the Tuluní Substation. This 115 kv substation is conventional, has a simple busbar configuration, and is located in the municipal capital of Chaparral, Tolima, where the power plant delivers its energy to the national grid. To ensure the proper operation of the main equipment described above, the power plant has auxiliary mechanical and electrical equipment, as well as control and protection systems.