Ossberger cross-flow turbine provides electricity from a Philippine water channel4 min read

29. August 2016, Reading Time: 3 min

Ossberger cross-flow turbine provides electricity from a Philippine water channel4 min read

Lesedauer: 3 Minuten

The Bulanao hydropower station project was completed successfully in the Philippine province of Kalinga in March 2016. It is a new, small-scale power station on the irrigation watercourse …

… of the Upper Chico River Irrigation System (UCRIS) in the Bulanao district of Tabuk City. The operators, DPJ Engineers and Consultants (DPJ), have decided to install a cross-flow turbine made by the well-established German specialists, Ossberger, for the generation of hydropower.

Bulanao power station is a water diversion plant along the UCRIS irrigation channel. A portion of the canal water is diverted through an intake structure into a short head race with integrated trash rack, before entering the 40 m long pressurized penstock, leading down to the power house, where it enters the turbine inlet. The gross head value is around 22 m and the maximum water flow is 6 m³/s. The production of electricity is done by a 1000 kW Ossberger cross-flow turbine with a horizontally coupled synchronous generator. In an average year the operators expect to produce around 5.77 GWh of green electricity.

The operating company DPJ was founded by the qualified civil engineer Dan Peckley in February 2008, and specialises in advisory services for engineering and for public sector infrastructure projects in the Philippines. DPJ was handed the responsibility for planning and operating the Bulanao station. DPJ was involved in the entire project sequence, from initial conceptualisation to compiling detailed technical and cost-related feasibility studies. Similarly, the company was responsible for obtaining all the necessary bureaucratic and ecological permits, and for sealing a power purchase agreement with the Philippine energy providers KAELCO which is currently intended to run for 15 years.

At the beginning of last year, as soon as all the requisite permits had been obtained from the respective authorities, construction work commenced with the building of the water catchment system. At almost the same time work began on preparing 40 m of the surface route conduit for the works water. The high pressure pipeline was manufactured using solid steel with a diameter of 1.91 m. In the later part of the summer of 2015, once the concreting of the powerhouse had been completed, the machine set was then installed.

All of the electro-technical and hydro-mechanical equipment for the facility was provided by the German manufacturer Ossberger. Electricity is generated by a cross-flow turbine with dual cell guide vanes. Using two differently sized cells is ideal for hydropower plant locations with varying flow volumes. The standardised construction of Ossberger turbines enables them to be precisely custom-built to the requirements of every project. This type of modular system also facilitates economies on the manufacturing side, in turn benefitting the customer at the end of the line.

The centrepiece of the cross-flow turbine is a drum-shaped rotor with blades manufactured according to a well-proven method using foil shaped steel plates. Depending on its size, the rotor is fitted with up to 37 blades supported by multiple intermediate discs. This gives the turbine runner its extreme strength and stiffness and also prevents the occurrence of unwanted vibration. Ossberger turbines are fitted with standard self-aligning roller bearings which, theoretically, have an unlimited lifespan. The bearing housing and bearing itself form one single unit and allow the runner to be removed radially without having to dismantle the bearing housing of the turbine shaft. Another advantage of the patented bearing construction is that no grease or lubricants can leak into the water. It also helps to centre the runner in relation to the turbine housing. Maintenance-free sealing elements round off a very clever technical solution. This aspect is of particular interest to hydropower plant operators because, apart from the necessity of annual grease changes, there is no further need for maintenance work on the turbine bearings.

In addition to the machine set with a horizontally coupled Hitzinger synchronous generator converting mechanical into electrical energy, the entire electro-technical control system with switch gear and the hydraulic system were also supplied by Ossberger. A hydraulic governor is used to regulate the turbine to ensure smooth plant operation with automated power plant control. Bulanao power station should have gone into operation last year, but at the end of 2015 it was necessary to carry out maintenance work on the UCRIS irrigation channel due to flood damage. This caused the start-up and commissioning to be delayed for several months. However, at the beginning of March 2016 the new small-scale power plant finally went online.