Two new turbines from Czech turbine manufacturer Hydrohrom are helping to increase efficiency at the recently refurbished Klecany small hydro power project

IN 1899, a needle weir was constructed in the bend of the Vltava river in Prague, Czech Republic, to make the river more navigable. This was then reconstructed and modernised in 1977-81 to a tilting gate weir type, after it was destroyed by flood.

Following the reconstruction, a small hydro plant was installed on the weir between 1983-87 as part of the Klecany small hydro power project. The plant, owned by the Vltava River Authority, featured four kaplan turbines with a maximum output of 272kW.

In 1999, the Vlatava River Authority decided to modernise Klecany following the project’s high failure rate and low output, and awarded Czech turbine manufacturer, Hydro-hrom, the complete turnkey contract for the project.

As part of the project, Hydrohrom installed two new SSK 2300 turbines at the site. Commissioned in July 2001, the turbines are semi Kaplan type, with operational plate closure, fixed guide vane wheels with seven blades, and an automatically regulated runner.

Belt drive system

The Straight-flow horizontal S-turbine drives through a belt drive system with a flat belt horizontal synchronous generator, which features a nominal output of 600kW. The power generating unit has been designed to run throughout the year with the constant maximum output corresponding with head conditions of the site.

The belt drive system features a Siegling high efficiency flat belt, which offers the advantages of low noise output, together with easy maintenance and repair, says the company.

The unit operates with maximum power utilisation of available heads and flows, including water level regulation which insures that the water level does not decrease under a given limit.

Turbine closure is now controlled by a hydraulically operated sluice gate – located in the gate pit in front of the machine room – with hydraulic control of the gate situated in the machine room.

Controlled by a programmable logic controller (PLC), the generating set operates automatically in parallel with the grid, in co-operation with alarm automatics and water level regulation. The alarm automatics includes electrical protections and limit sensors of levels, positions and pressures and temperatre sensors.

Automatic regulation of the unit is also controlled by the PLC to provide all functions for optimisation and safety of the project’s operation, including screen cleaning machines and machine room ventilation. The controlsystem allows remote control and monitoring of the power station.

In case of grid failure, turbine discharge is now stopped automatically by closing the sluice gate and by disconnection from the grid. The distributor of the hydraulic power pack servomotor switches off the sluice gate, which is then safely closed by gravity. After renewal of grid voltage the turbine-generator restarts automatically.

Cooling air inlets

As part of the new system, the machine room has cooling air inlets and outlets over the level Q100. Air supply and exhaust are distributed by fans connected to the unit.

Each turbine has a separate inlet with fine screens, with a distance of 40mm between the bars. The screens of each turbine are cleaned by separate automatic hydraulic trash rack cleaning machines. There is also an electronic fish repellent installed in the intake to be the differnt secies of fish in the area.

Erection of the machinery used in the project, which cost US$1.95M, was aided by the use of a overhead travelling crane with a lifting capacity of 15t. Once it is fully uprated, it is expected that the power plant will generate approximately 7M kWh annually.

Turbine parameters…