The influence of a hydropower plant on the environment is analyzed. The frequent starting and stopping of hydropower plant turbines are considered to cause the erosion of river-bed and damage to river flora, fauna and the environment generally. The harm may be reduced by passing the entire runoff of the river through turbines without changing the flow of runoff and the accumulation of water in a reservoir [Khmpt J-E, Riveiro C, Puranen H, Koch F. Recommendations for sustainable hydroelectric development. Energy Policy 2002; 30(14): 1305-1312]. This idea cannot be realized in a traditional hydropower plant. The range of runoff changes of Lithuanian rivers is much broader than the capacity of one or more turbines of the same power. The characteristics of several turbine types are analyzed. The carrying capacity of a cross flow turbine is regarded to have the widest range. In addition, the width of the range may be expanded with special auxiliary equipment. This type of turbine is equivalent to two or even three turbines of varying capacities, and it can handle the discharges from any season. The possibilities for expanding the range of turbine capacity by means of working with varying speeds of rotation are discussed. Special mechatronic systems for controlling mechanical and electrical equipment of a hydropower plant, working with varying speed of turbines revolution, are presented. The investigation of mathematical models of the systems under both autonomous and systematic regimes shows their efficient operation and sufficient quality of electrical power. (c) 2006 Elsevier Ltd. All rights reserved.
