Numerical simulation model of run of river hydropower plants: Concepts, Numerical modeling, Turbine system and selection, and design optimization

Hydropower is a relatively cheap, reliable, sustainable, and renewable source of energy that does not consume natural resources nor produces emissions and toxic waste. In fact, compared to all other energy sources, hydropower is the least expensive and most efficient method for generating electricity, with a price competitive to traditional energy sources such as fossil fuels, gas, and biomass. Most hydroelectric power that is being generated in the world today comes from (large) hydroelectric dams that generate electricity by converting the potential energy of falling or running water from human-made reservoirs. These reservoir-fed plants distort significantly the local environment and ecosystem, and hence much opposition exists towards their use and construction. Run of the river (RoR) hydroelectric stations are a viable alternative to large-scale plants as they require no reservoir capacity, so that the water coming from upstream must be used for generation at that moment, or must be allowed to bypass the station. This is a key reason why such RoR plants are often referred to as environmentally friendly, or green power. Here, we introduce a numerical model, called HYdroPowER or HYPER, which simulates the daily power production of a RoR plant in response to a historical record of daily discharge values, and design and operation variables. HYPER constitutes the first numerical model that takes into explicit consideration the design flow, penstock diameter, penstock thickness, specific speed, rotational speed, cavitation, and suction head in evaluating the technical performance, production, cost, and profit of a RR plant. The model simulates both single and parallel turbine systems involving Kaplan, Francis, Pelton and crossflow turbines and combinations thereof. HYPER is coded in MATLAB and includes a built-in evolutionary algorithm that optimizes automatically the design of the hydropower system of the RoR plant for a given record of river flows and objective function (maximization of net profit or power production). This algorithm can be called from the main model script and maximizes (among others) the type and number of turbines, their design flow, and the penstock diameter. Finally, we introduce a graphical user interface (GUI) of HYPER which simplifies numerical simulation and interpretation of the results. Three different case studies are used to illustrate the power of HYPER. The model and its different components is available upon request from the authors