The latest issue of Dam Engineering (Volume XXIX, Issue 1) has been published. The journal includes two technical papers (abstracts below):
Time harmonic analysis of concrete gravity dam-reservoir systems using Wavenumber-TD approach for general ground excitation
by Hamid T Ganji & Vahid Lotfi
Abstract: In recent years the Wavenumber approach has been introduced, which may be envisaged as a great substitute for rigorous types of analysis. The former technique is formulated in the context of pure finite element programming, while the latter relies heavily on a two-dimensional semi-infinite fluid element. However, both of these methods are carried out in frequency domain. Thus, the Wavenumber technique in its original form may be more accurately designated as the Wavenumber-FD approach. Subsequently, a variation of the Wavenumber method was proposed which is referred to as the Wavenumber-TD approach. The approximation to the original technique improves its realm of application and allows it to be carried out in time domain as well as frequency domain. In the present study, this approach is generalized such that it could handle a general excitation which may also include vertical ground motion. The method is initially described. Thereafter, the response of an idealized triangular dam is studied due to either horizontal or vertical ground motion under the full reflective or absorptive reservoir base condition.
Optimization of run-of-river hydropower plant capacity
by Getachew E Mamo, Miroslav Marence, Juan Carlos C Hurtado & Mário J Franca
Abstract: Run-of-river (RoR) hydropower plants are one of the most viable and environmentally friendly energy sources. The development of this type of hydropower project is highly dictated by the technical feasibility and financial viability of the project, which reflects in the optimal configuration of the system. This technical and financial viability is sensitive to natural (river flow and head) and financial constraints, as well as to project construction costs. Classically, a river flow which equals or exceeds between 50 and 120 days a year, and gives maximum energy output, is selected as a design discharge for RoR power plants. The selected discharge giving maximum energy output may not be the optimal design discharge that assures the plant’s optimal system configuration with minimum construction cost. This study presents a mathematical model used to determine the design discharge, installed capacity and number of turbines needed for optimal configuration of run-of-river hydropower plants based on the optimal operational rule defined for RoR hydropower plants. The electromechanical cost, which includes the turbine, generator and regulators, is used as an input parameter to estimate the specific cost of energy production. This is estimated as the ratio between the total cost of a run-of-river power plant and maximum total annual energy production. The developed model is tested with real data from an existing plant. The herein proposed RoR power plant, based on simulations with our model to provide the optimal parameters, has 25% less production costs than the existing run-of-river power plant case study. This model can be used as a decision support tool for investors, decision-makers and manufacturers for RoR hydropower development.
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