How Is A Hydropower Turbine Constructed?

Hydropower is the process of generating electricity by harnessing the power of flowing or falling water. A hydropower turbine is the component that converts the kinetic energy of water into mechanical energy by spinning when water flows through it. The turbine shaft is connected to a generator which converts the mechanical energy into electrical energy. Hydropower turbines serve the vital purpose of generating clean, renewable electricity from water power in an efficient and reliable manner.

A turbine is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The purpose of hydropower turbines is to convert the natural potential and kinetic energy of water into electricity. Turbines have blades or runners with specially designed curves that capture the movement of water, which causes the shaft and rotor to spin. This rotational energy drives the generator to produce electricity. There are several types of hydropower turbines, each designed for different water flow conditions and power output capabilities.

Table of Contents

Planning and Design

The planning and design process for a hydropower turbine is complex, requiring extensive analysis and engineering. The location of the turbine is a major consideration, as factors like the head height and flow rate of the water source will determine how much power can be generated. The capacity or generating output of the turbine in megawatts (MW) also needs to be determined based on the site and projected energy demands.

There are several types of hydropower turbines to choose from, including Kaplan, Francis and Pelton turbines. The choice depends on the head height and flow rate of the water. Kaplan turbines are well-suited for low head sites, while Pelton turbines are used for high head installations. Francis turbines can operate over a range of head heights.

The materials used to construct the turbine are critical. The housing is usually made of steel, while components like the blades, shafts, vanes and spear valves are made from stainless steel or other alloys. The materials must be strong, durable and corrosion resistant. The size, shape and angles of the blades and vanes will depend on the specific turbine design and desired efficiency.

The civil engineering works like dams, tunnels, pipelines and spillways also require extensive planning. Environmental factors like fish migration must be considered. Hydrological data on the river’s seasonal flow rates assists with developing optimal turbine operation parameters. The turbine design process brings together various engineering disciplines and takes into account many technical, commercial and environmental factors.

Manufacturing the Components

The major components of a hydropower turbine, such as the blades, shaft, casing, and more, are manufactured from raw materials through processes like casting, machining, and forging. The raw materials used depend on the design requirements. For example, the turbine blades may be made of stainless steel, cast iron, or composite materials. Blades are often cast to near-net shape, then machined to final dimensions. The shaft is usually forged from alloy steel and machined for precision. It needs to be strong enough to transmit torque from the turbines to the generator.

The casing that houses the turbine is made from steel or concrete, depending on if it’s an enclosed design or open-flow. Steel casing components can be fabricated from welded steel plates. The wicket gates, which regulate water flow onto the turbine blades, are manufactured through similar metal casting and machining methods. Bearings are made from alloys like babbitt metal to withstand high-pressure water environments. Thegenerator rotor and stator are fabricated separately, sometimes involving highly specialized processes like high temperature vacuum brazing. All components must be precision manufactured to tight tolerances to achieve optimal efficiency.

Assembling the Turbine

The assembly of a hydropower turbine is a complex process that requires precision engineering and skilled technicians. It takes place in a large workshop specially equipped for the task. The main components – the runner, shaft, wicket gates, casing and bearings – first go through quality control checks and inspections before being brought to the assembly area.

The process begins with the runner, which is the bladed rotating part inside the turbine that captures the hydropower of the water. The runner is carefully lifted and seated on the main shaft, which has already been assembled and tested. Great care is taken to align the runner perfectly on the shaft. The runner blades are then bolted or welded to the shaft.

Next, the wicket gates, which control water flow onto the runner, are installed around the runner. They are positioned precisely to guide the water at the correct angle to achieve maximum efficiency. The wicket gates are attached to linkages and actuators that can adjust their angle.

The turbine shaft is then seated inside the bearing housing, which will allow the shaft and runner to spin freely inside the turbine casing. The housing contains bearings and seals that reduce friction on the shaft. The entire bearing assembly gets bolted to the interior of the casing.

Finally, the two halves of the casing are bolted together around the central rotating parts. Great precision is required to align the two halves perfectly. The fully assembled turbine is then tested and calibrated before being shipped to the dam installation site.

Installing the Turbine

Once the turbine components are fully assembled and tested, the next major step is transporting the massive turbine unit and installing it in its final position at the dam or water intake. First, the turbine is loaded onto a large heavy transport trailer designed specifically for moving heavy machinery. The trailer has specialized axles and suspension systems to handle the enormous weight.

When arriving at the dam, the turbine is carefully offloaded using large cranes and lifting equipment. The installation area is prepared with strong, stable foundations and mounting points to secure the turbine. The turbine is then hoisted into position using cranes and guided slowly into place. It is secured to the reinforced mounting points with enormous bolts and thick anchoring.

Extreme precision is required when lowering the turbine onto its mountings to avoid any damage during installation. The whole process is planned out extensively beforehand using engineering calculations and computer models. It requires coordinating teams of riggers, crane operators, and installation technicians working together to safely secure the turbine. Proper installation is critical for the turbine to operate as designed over its 30-60 year lifetime.

Connecting Generators and Controls

After the turbine is installed, the next step is to connect the electric generators and control systems. Most hydropower turbines have their own generators located directly at the turbine to convert the mechanical rotation into electrical energy. These generators are specially designed for the high-speed rotation and water environment inside a hydro turbine. They are directly coupled to the turbine shaft to turn as the turbine spins.

The electrical cables from the generators are routed out of the turbine housing to transformer stations. These step up the generator’s output voltage to higher levels for efficient transmission over long distances on the grid. Protective relaying and switches are installed to protect the generators and interconnect with the grid.

The turbine also requires electronic or hydraulic control systems to regulate water flow, speed, and power output. Sensors provide feedback on turbine conditions back to a central controller. This controller continuously monitors the system and adjusts wicket gates, blade angles, and other parameters to maintain steady and efficient operation throughout fluctuations in water flow and grid demand.

Connecting the power generators, control systems, and grid is a complex integration task. But once completed, the turbine can begin converting the power of water into useful electricity for society’s needs.

Testing and Commissioning

Once the turbine installation is complete, extensive testing and trial runs are conducted before the turbine is officially commissioned and handed over. The turbine components, mechanical systems, electrical systems, and control systems undergo rigorous individual testing first to ensure each operates properly.

The turbine rotors and shafts are spun to check smooth operation, alignments, rotational speeds, vibration levels, and bearing temperatures. The intake gates, wicket gates, and draft tubes are tested to ensure they can regulate water flow as designed. Generators and electrical switchgear are run through electrical tests to confirm insulation, grounding, voltage, and load capabilities.

The turbine control and safety systems are checked to verify they can regulate turbine speed, detect issues, and trigger automatic shutdowns when required. Instrumentation like pressure sensors, temperature probes, and speed sensors are calibrated. The monitoring and SCADA systems are configured and tested to confirm remote control capabilities and data logging.

After individual component and system testing is complete, the entire turbine generator unit undergoes a trial run. The turbine is slowly spun up to operating speed and various load scenarios are simulated to observe performance. Multiple start-up and shutdown sequences are conducted as well. For pumped storage turbines, both generation and pumping modes are evaluated. Engineers closely monitor all parameters and make final adjustments as needed.

Once the turbine operates stably at full load, meets all design criteria, and passes final inspections, it is officially commissioned and released for normal operation. However, turbines continue to be monitored closely during the initial operating period for any signs of problems. Operators also receive extensive training on proper procedures and protocols during this stage.

Maintenance

Hydropower turbines require regular maintenance throughout their operational lifetime to keep them functioning efficiently. Some key maintenance activities include:

Inspecting turbine components for signs of fatigue, cracks, erosion, or other damage. Visual inspections are done routinely, while more detailed inspections requiring disassembly occur every 5-10 years.
Lubricating bearings, seals, and other moving parts. Oil levels are checked regularly and changed periodically.
Replacing worn or damaged components like runner blades, wicket gates, seals, and bearings. This is done as needed based on inspections.

Testing and calibrating monitoring equipment and control systems. Sensors, gauges, actuators are checked and recalibrated periodically.
Cleaning debris and silt buildup in water passages. Buildup can reduce efficiency and cause abrasive damage.
Checking and tightening bolts, fasteners, and joints. Vibration can loosen components over time.

Coating metal surfaces with anti-corrosion products. This protects against pitting and rust caused by water.
Troubleshooting issues and performing repairs as needed to optimize performance and longevity.

With proper maintenance, modern hydropower turbines can operate reliably for 50 years or more. Maintenance keeps efficiency high, prevents unexpected outages, and reduces major repairs down the road.

Upgrades and Refurbishment

Hydropower turbines require periodic upgrades and refurbishment to improve their efficiency and extend their operational lifetime. As technology improves, older turbines can be retrofitted with more advanced components and optimized control systems.

One common upgrade is replacing the runner, which is the rotating part of the turbine that extracts energy from the flowing water. New runner designs made from advanced materials and computational fluid dynamics modeling can increase efficiency by several percentage points. Replacing worn runners on older turbines provides an inexpensive efficiency boost.

Upgrading aging control systems with digital controllers can also improve turbine performance and responsiveness. New control systems provide improved regulation of voltage and frequency as power demand fluctuates on the grid. Advanced controllers also enable remote monitoring and control capabilities.

Refurbishing turbines includes replacing seals, bearings, packing glands, worn parts, and oil or cooling systems. Periodic inspections identify components in need of repair or replacement. Regular maintenance and refurbishment ensures turbines continue operating safely and productively over their typical lifespan of 50 years or more.

Ultimately, upgrading and refurbishing hydropower turbines extends the value of existing infrastructure while also making the most of limited water resources for carbon-free renewable electricity generation.

Conclusion

Constructing a hydropower turbine is an extensive and complex process that requires expertise in engineering, manufacturing, and construction. The main steps involved include: planning, design and engineering of all components and assemblies; precision manufacturing of the turbine parts such as the blades, shafts, and housings; assembling the turbine assembly; installing the complete turbine unit on site; integrating the turbine with generators and control systems; thoroughly testing and commissioning the installed turbine; and ongoing maintenance and upgrades as needed.

Each step requires great care and attention to detail, as small flaws or variations from the original specifications can lead to underperformance, inefficiency, or breakdowns. High quality materials, controlled manufacturing methods, and rigorous quality control and testing ensures the turbine meets its design parameters. The result of proper construction is a durable, optimized hydropower turbine able to maximize energy generation throughout its operational lifetime.