Operation of the Shaft Low Head Hydropower Plant
1. Dam and Gate
The dam is a conventional concrete river dam, except a vertically adjustable gate is fitted to the wall about mid-length section. This controls the level of the river through overflow from below or above the gate allowing the safe passage of fish up or downstream of the plant.
2. Turbine Plant.
The plant is installed as a complete module into a vertical shaft, then a wire mesh debris screen is fitted across the top.
The completely submerged low head turbine can be either reaction such as a propeller, or an impact turbine such as a cross-flow type depending on the river flow velocity available.
The water passes through the screen through a bulb turbine that uses a propeller to drive the integral power generator. The bulb turbine can also incorporate adjustable guide vanes/wicker gates to give optimum water direction and flow to the propeller blades. The water now continues through a draft tube into the tailrace and re-enters the river behind the dam.
Note: I have used a vertical bulb turbine in the sketch, as this would be my first choice of water turbine. (Remember my sketch is what I interpret a unit will resemble.)
3. Power Output Cables
The power cables can be run up the dam wall and onto the riverbank where they are connected to the substation. From here the power cables are buried and run to the house/final location.
Below is a sketch of the low head hydropower unit using a vertical bulb turbine, please click on it to enlarge:
- Low Head Hydro, Third World
Small is Beautiful
Low Head Hydro