020911_MH - Proceedings of the Hydraulic Machinery and...

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Proceedings of the Hydraulic Machinery and Systems 21st IAHR Symposium September 9-12, 2002, Lausanne PROPOSAL OF VARIABLE SPEED SYSTEM FOR MICRO- HYDROPOWER USING CROSS-FLOW TURBINE Linhu ZHAO, Hashimoto Sangyo Co., Ltd./New Product Development Dep., Tokyo, Japan Junichi KUROKAWA, Yokohama National Univ./Faculty of Eng., Tokyo, Japan Jun MATSUI, Yokohama National Univ./Faculty of Eng., Hiroshi IMAMURA, Yokohama National Univ./Faculty of Eng., Chittavong Khamphanh, Yokohama National Univ./Faculty of Eng., Tadashi TSUKAMOTO, Voith Fuji/Turbine Technology Dep., Tokyo, Japan Shoichi YAMATO, Fuji Electric Co., Ltd. / Environmental System Division, Tokyo, Japan ABSTRACT Conventional hydroelectric plant systems are not suitable for micro-hydropower because of relatively high cost. In this study, two variable speed micro-hydropower systems that consist of low cost commercial power electronic elements are proposed for variable head micro- hydropower. One is for the purpose of applying to isolated operations, and the other is for connecting to power systems. The experimental results revealed that turbine performance and overall system efficiency at off-design heads can be improved much by using these systems. The performance characteristics of a low head cross-flow turbine that is simplified by the authors are also investigated experimentally in a wide range of operating head. NOMENCLATURE Term Symbol Definition Term Symbol Definition Effective Head H Measured from the water surface in the tailrace Air Pressure Inside of Runner p ri At normal condition Rotational Speed n For turbine Rotational Speed For generator Outer Diameter of Turbine Runner d Exciting Frequency F For induction generator Runner Width b Synchronous Speed N s For generator Water Density Turbine Output Power P Turbine Efficiency t Overall Efficiency Efficiency of Turbine with Generator tg Exciting Voltage V For induction generator
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Proceedings of the Hydraulic Machinery and Systems 21 st IAHR Symposium September 9-12, 2002, Lausanne 23.04.2002 2 INTRODUCTION It is important to exploit micro-hydropower (less than 100kW) as a decentralized power resource. However, when applying scaled-down models of conventional hydropower systems and turbines to micro-hydropower schemes, the cost increases excessively due to the lack of scale-merits (Ref. 1). Thus, it is expected to develop non-conventional hydropower systems and turbines appropriate for micro-hydropower. When a micro-hydropower system is located apart from power supply system, the cost- effective governor is an Electronic Load Governor (ELG) that adjusts an electrical ballast load (Ref. 2). According to the present experimental investigation, a constant speed system that consists of a synchronous generator and an ELG caused rapid drop in efficiency when the operating head deviates from the designed head. On the other hand, when a micro- hydropower system is located near the power supply system, the simplest way is to use a cage-type induction generator connected directly to the power system. However, such a
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This note was uploaded on 05/05/2011 for the course FC gj, taught by Professor Glokgh during the Spring '97 term at Punjab Engineering College.

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020911_MH - Proceedings of the Hydraulic Machinery and...

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