zek.at | Artikel drucken

Chile’s Río Colorado power plant connected to grid under high voltage

The Chilean utility company “Gestión de Proyectos Eléctricos” (GPE) began operating a new hydropower plant in the Chilean Región del Maule in March 2017.

The plant, which is equipped with two Francis turbines, utilises the potential energy from the Río Colorado, which has its source close to the national border with Argentina. The Austrian manufacturer Global Hydro Energy GmbH was able to supply a complete electromechanical package and in so doing add another perfectly implemented hydro­power plant to its extensive list of international reference projects. In addition, the turbine manufacturers gained valuable know-how for future projects by implementing compact high-voltage switchgear for the first time.

As the world’s longest range of mountains above ground, the Andes extend along the west coast of the South American continent through Colombia, Ecuador, Peru, Bolivia, Argentina and Chile. They extend for a vast 7,500 km from north to south. Together with the Amazon, the river containing the most water in the world, the huge mountain range forms the backbone of the potential for hydropower in South America. “In Chile, for example, the region in the central area of the country in which the Río ­Colorado rises is the source of around 20% of the hydropower which is generated across the country,” remarks Thomas Schweiger, GPE project manager for the new hydropower plant which was completed in spring 2017. Although the amount of water available at the location naturally fluctuates with the different seasons, the operators expect a comparatively high capacity utilisation factor of between 50 and 70%.
Classic diversion principle
The plant in the Chilean Región del Maule was implemented using the classic diversion principle; the construction work lasted for a total of around 2.5 years. A transverse structure constructed with a solid concrete design dams the Río Colorado and guides it into an open weir channel. According to the official specifications, the prescribed delivery rate will fluctuate in a range of at least 1.5 to no more than 3 m³/s. According to project manager Schweiger, the construction of the open weir channel stretching over many ­kilometres required a great deal of structural and organisational effort and outlay. The ­rocky terrain meant that there was no option but to use explosives on multiple occasions. Following an open-air section of around 5 km, the waterway transitions into a closed penstock made from steel pipes laid largely above ground. The final section of pipework has a consistent dimension of DN2200 and extends for a length of 530 m. Shortly before the water is turned into power in the powerhouse, the penstock is divided by a Y-branch pipe which is laid underground.

Turbines in the medium power range
“The bid for the ‘Río Colorado’ project fitted our technical portfolio precisely from a hydro­mechanical point of view. Although the two Francis turbines with a spiral casing were not the biggest machines that we have ever manufactured, with a power output of around 8.4 MW each they still fall within the medium power range of what is offered by GLOBAL Hydro. The benefit that this produces for the end customers is that they can rely on a well-developed product that is manufactured at a very high technical level as standard. All machines are subjected to our tried-and-tested quality procedure both during and before construction, and ultimately arrive at their intended destinations as highly effective suppliers of electricity,” says GLOBAL Hydro project manager Dietmar Lehner. The company delivered this contract as what is known as a “water to wire” project – all of the electromechanical components were fully manufactured or provided by GLOBAL Hydro, properly installed and commissioned. For the new power plant on the Río Colorado, two completely identical Francis machines with a horizontal shaft and a design discharge capacity of 5.5 m³/s each were manufactured. The turbines are provided with a net drop height of 168.7 m, which allows a maximum power output of 8,402 kW to be achieved by each of them. Each of the hydraulically controlled turbines has a rotational speed of precisely 750 rpm. The energy converters used are two synchronous generators, which also have exactly the same design and are each coupled directly to the turbine shafts. A high-voltage power line stretching for around three kilometres above ground was constructed to feed the power into the public power grid.

Switchgear with hybrid design
“When it came to the electrical part of the assignment, we opted for a special solution that we had never before implemented in this form,” explains GLOBAL Hydro project manager Thomas Stütz: “And specifically for the first time we ­supplied high-voltage switchgear with extremely compact dimensions. To be more precise, the equipment has a hybrid design – the switchgear consists of both air-insulated and gas-insulated components and is fully preassembled during the manufacturing stage. This design, which we implemented together with the manufacturer ABB, won over the clients primarily thanks to its comparatively small dimensions. As only a limited amount of space was available on the back of the powerhouse, compact high-voltage switchgear was the ideal solution for the end customer. By implementing switchgear of this design for the first time, we also acquired very substantial know-how. This means we are now also able to offer our customers a 110 kV high-voltage output on the electrical side.” Another new aspect for GLOBAL Hydro in the Río Colorado project was the size of the transformer. As this could not be transported in one piece due to its size, the transformer was dismantled into individual parts capable of being transported and then reassembled on site.

Everything interlinked
According to Thomas Stütz, another challenge of the project was meeting the control requirements of the Chilean grid operator. For example, to do this it was necessary to set up a communication ­control system which is based on the “DNP 3.0 protocol” (software protocol for network communication) and enables a constant transfer of data between the hydropower plant and the grid operator. “Implementation of the system in consultation with the grid operator on site was extremely complicated in organisational terms. ­Thomas Schweiger from GPE was a big help to us when it came to ­interacting and clarifying matters with the companies and local contacts on the ground,” states Dietmar Lehner. In terms of network­ing, apart from the connection to the grid operator’s ­system, further electrical components and substations belonging to the ­client were also integrated into the plant control system.

Power plant SCADA system
For turbine control, GLOBAL Hydro supplied the intelligent “heros 3” control software which it developed itself. Thomas Stütz adds: “When it comes to the turbine controller, the term ‘power plant SCADA system’ is really more accurate. Starting with the ­generator and turbine control, the entire medium-voltage and high-voltage system and a separate high-voltage station of the end customer several kilometres away was also added to the visualisation of the control system. With “heros 3” electricity is produced in ­fully automated fashion and, thanks to online connection, there are ­extensive options for remote control and maintenance. Incidentally, last year we installed a control system of similar complexity at the “Oxec I” hydropower plant in Guatemala in Central America.”

On the grid since the spring
With regular operation having commenced in March 2017, GPE project manager Thomas Schweiger can now draw a positive ­conclusion: “The plant is running very satisfactorily and effectively, which at the present time is down to the high quality of the machinery equipment and software. The project was definitely also boosted by the excellent collaboration and communication with the companies involved.” In a normal year, the new power plant on the Río Colorado will generate around 79 GWh of green electricity, with all of the power going into the public power grid. During the course of this year, GPE is planning to complete another 27 MW hydropower plant on a reservoir in the Región del Maule.

© zek.at