Hydropower systems come in different sizes and designs depending on the type of project and the manufacturer but they all operate under the same principle. The aim is to convert the pressure exerted by a water head into mechanical power. The mechanical energy then turns a generator to produce electricity.
Parts of a hydropower system
- Penstock pipe
- Draft tube
- Export power cable
The structure of a hydropower station
The structure of all hydropower systems is the same irrespective of the size. Each system has an intake on the upstream side through which water flows into the hydro turbine. The intake has a sieve which prevents rocks, debris and other solid materials from getting inside the turbine and causing damage. The sieve also prevents fish and other aquatic animals from getting sucked into the system and suffering injury or even death.
After the water has passed through the sieve, it flows into the penstock pipe which leads to the turbine. The penstock channels water through a narrow pipe to maximise its pressure. It is always full such that the pressure increases with every increase in the head as the water flows downwards.
The turbine is at the end of the penstock pipe and has a rotor which rotates when it is pushed by high pressure water. The turbine traps the water and continues rotating until the pressure is minimal. The plant is designed in a way that the water discharges at the lowest point to extract maximum energy from it.
Inside the turbine
Inside the turbine, the water runs through a draft tube which exerts negative pressure on the system. The draft tube acts as a suction that reduces air pressure by having a column that sucks in water through gravitational pull. This mechanism is why the draft pipe is often called the ‘suction head’ while the penstock is called the ‘pressure head’.
The draft pipe exerts negative pressure while the penstock exerts positive pressure on the system. It is why the system always starts with some water in the draft pipe. Draft pipes allow engineers to setup power stations on dry ground several inches above the lowest water level. Such sites are easier to construct and use while operating the hydropower station.
Converting mechanical energy to electricity
Inside the turbine is a gearbox or belt-drive that converts the low-speed, high-torque rotation into high-speed, low-torque power. The power from the gearbox then drives a generator to convert the mechanical energy into electricity. The generator contains magnets that rotate to convert mechanical energy into electricity through induction. The export power cable carries this electricity for different applications.
Why choose us?
Hallidays Hydropower International are a global hydropower consultancy based in the UK. We have expertise in the construction and maintenance of small run-of-river hydropower schemes that are environmentally friendly. We handle all stages of plant operation from conceptualisation and site construction to maintaining and servicing existing plants. You can rely on us for the delivery and maintenance of hydropower schemes on your property.
Back to Blog