Objectif To demonstrate:(a) the use of a twin runner Pelton wheel to improve efficiency over a wide range in flow rates and(b) the use of a composite sand, chopped glass fibre and resin pressure pipe.The energy production is 3,300,000 kWh and the total unit cost is 0. 04 ECU/kWh.Installation to the grid was effected in April 1991 and after commissioning, entered regular service a month later. All electricity produced is exported to the grid.TURBINE : The overall turbine performance remains fairly constant at 84.5% throughout its entire operating range. This confirms the suitability of the design for such run-of-river sites where a large proportion of the turbine load is in the part-load range.PIPELINE : The pipeline has proven satisfactory in achieving the objectives of economy, ease and installation and durability. The nature of the soluble salts and bacteria in the water feeding the turbine has been found to encourage the growth of slime under certain conditions. It is necessary to monitor the extent of the slime deposit to allow for cleaning when appropriate.CONTROL EQUIPMENT : A regulation module was purpose designed to maintain satisfactory flow balancing between river and turbine. Remote operation of the plant is under software control which provides for equipment condition monitoring and logging of alarms or faults as they arise.GENERATOR TRANSFORMER : It was originally intended that the star points of generator and transformer would be bonded and grounded. However, at full load, this was found to induce harmonic distortion and oscillation about the neutral point. The neutral point of the generator has therefore been left to float to permit satisfactory operation.TRASH RACK : The original trash rack has been replaced with a novel back flushing arrangement at the intake. This incorporates an automatic system for opening a by-pass gate which allows trash and sediment to be flushed into the original water course.The economic viability of the plant could be improved by including a storage reservoir, the effect of which would be to reduce the payback period from 10.8 to 8.3 years. It remains the contractor's intention to build such a reservoir. However, difficulties with land purchase prevented construction during the course of the project.At 75 metres, 1.8 cumecs this site would traditionally have been developed with a low specific speed Francis turbine.Part load efficiencies would have been poor under the wide range of flows. A six-jet, twin runner Pelton turbine with high specific speed provides higher efficiencies down to 1/6 flow, form a simpler cheaper constructionThe potential disadvantage of extra flow regulation equipment is minimised by providing precision flow control to only one jet per runner, with the other jets having simple on-off gate valves. A simple fail-safe deflector mechanism has been developed to prevent overspeed on load rejection. The deflectors are held under tension by electromagnets energised from the grid: if the grid voltage is lost, powerful springs insert the deflectors to prevent overspeed.Glass reinforced plastic pipes have a number of advantages over steel pipes in small hydro applications: they can readily be custom made for each project, are lightweight, and easily joined. This project uses a centrifugally cast composite, with a thick wall to prevent negative pressure buckling made by the careful inclusion of sand. Two resins are used in manufacture a low elongation resin for the majority of the pipe wall, but a high elongation resin for the pipe-liner where high tensile strains are experienced due to pressure and bending.Head 72.5 metres (gross)Flow 1.8 m3. s-1Power 870 kWTurbine PeltonTurbine speed 300 rpmGenerator speed 1000 rpmGenerator asynchronousEnd-use grid connected Programme(s) ENG-ENDEMO C - Programme (EEC) of demonstration projects and industrial pilot projects (EEC) in the energy field, 1985-1989 Thème(s) Data not available Appel à propositions Data not available Régime de financement DEM - Demonstration contracts Coordinateur OWENBERG NATURAL POWER COMPANY LTD Contribution de l’UE Aucune donnée Adresse CHARLEMONT MONKSTOWN Irlande Voir sur la carte Coût total Aucune donnée
