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Chilean La Viña power station provides operating reserve power

The completion and commissioning of the La Viña power station in Chile again enabled Ossberger to provide further proof of their expertise in the South American small-scale hydroelectric sector.

The plant was constructed along an irrigation channel at the heart of a wine-growing area in Región del Bío-Bío and Ossberger fitted it with a full range of electrohydraulic technologies. Working at full flow volume the robust crossflow turbine can generate a bottleneck capacity of 433 kW. The plant was built within just a few months and achieves an average yearly output of approximately 1,500,000 kWh of green energy. The electricity generated by ‘La Viña’ is used to guarantee the availability of operating reserve power and is traded on the Chilean ‘spot market’.

As well as providing a base for a variety of industries, the Central Chilean region of Bío-Bío is also the largest wine-growing area within this entire South American coastal country. Numerous irrigation channels deliver water to the busy wine-growing and agricultural areas. These artificial waterways are fed by sources such as the Río Bío Bío. The body of water forms a natural border with the northerly Mapuche region and, at a length of 380 km, it is the second-longest river in the country. In the fairly recent past, several small-scale hydropower stations have been built along a 30 km section of a 100 km irrigation channel. As the name La Viña (Spanish for wine mountain) suggests, the plant was built by HTL energía  – a Chilean project development company in a wine-growing area on the Licura-Munilque Canal. The company specialises in the utilisation of the hydro-energetic potential of irrigation channels and has already completed a whole series of similar projects around the country. The entire hydraulic and electrical infrastructure for the power plant, including the control systems, was provided by the German manufacturers at Ossberger. Distribution tasks were executed by the Chilean business Mantex S.A., a company active in the industrial, quarrying and energy sectors, whose portfolio also includes engineering solutions and the representation of numerous international enterprises.

A crossflow turbine unites many advantages
“Satisfying the numerous interest groups when it comes to authorising hydropower projects in these places is often a complicated business, since the use of irrigation channels is usually divided up between town councils, companies and private individuals”, explains Rolf A. Fiebig, CEO at Mantex S.A. “Fortunately, the La Viña project was an exception to the rule and a building permit was issued without any significant difficulties or delays.” Fiebig continued, explaining that from the very beginning the plant operators had intended to equip the hydroelectric power station with a crossflow turbine. “The principle behind the crossflow turbine is both simple and effective and, in combination with reduced maintenance requirements and excellent value-for-money, these are key deciders for the customer. In fact, Ossberger turbines have already proven their operational qualities at several plants in Chile.” Furthermore, one advantage of the machine that simply can’t be underestimated is its self-cleaning function. Driftwood and floating debris that enters the body of the turbine is pressed between the rotor blades and after just half a rotation is rinsed out by the escaping water, assisted by the centrifugal force of the turbine rotors.

Turbine generates 433 kW for power shortages
A compact weir with a channel outlet surge tank was installed 20 km from the town of Mulchén. If there is a power plant failure, the surge tank provides a bypass system for an automatic rerouting of the flow into the existing channel. Electricity production only requires a maximum of 5.2 m³/s of water to be directed down a 200 m DN1800 pipeline to the turbine of the functionally-designed power house. The turbine has a net head of 10.2 m. At full water capacity the machine can generate 433 kW of bottleneck capacity. The impressive rotor is 2.6 m across, rotates at a rate of 147 rpm and is connected with the asynchronous generator via a gear. The generator itself rotates at 1000 rpm and produces 392 kW.

Electricity for the regulated energy market
Although the volume of water flowing down the channel remains relatively stable, flow can drop to a minimum of 3 m³/s. Nevertheless, this in no way inhibits the capacity of the system to produce electricity with a crossflow turbine, particularly in the partial load zone where the machine achieves a constantly high degree of efficiency. The project developer ‘HTL energía’ says the plant provides 75% of maximum operative usage. The state-of-the-art power plant offers fully-automated electricity production. The electrical technology and control infrastructure ‘OTmation SCADA’ were also provided by Ossberger as part of the ‘water to wire’ job. The entire plant can be operated and monitored remotely online. Any operational disturbance is registered automatically by the control infrastructure and reported to the operator. In an average year the power plant can produce around 1,500,000 kWh of power. The output is fed into the public mains grid around 1 km away via overhead power lines especially constructed for the purpose. The power station went online in May 2017 after a construction period of just a few months. Rolf Fiebig confirms there has been a seamless supply of power since the system commenced operation, and that the customer is very satisfied. The electricity produced is utilised to guarantee operating reserve power for the national grid. Electricity is traded on Chile’s ‘spot market’. Hydroelectric power station operators are at a notable advantage in such an extremely dynamic business. The law states that the use of power emanating from renewable energy sources must always be prioritised when there is demand for operating reserve power.

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