This paper proposes a control architecture for frequency, current, and voltage control that facilitates using battery storage to improve the response of standalone small hydropower plants. The ...frequency controller uses rate-of-change of frequency and frequency-Watt-based generations to produce active power commands. The distinctive feature of the controller design is that it nicely integrates response to frequency change with constraints on frequency and state of battery to enable power injections. The current and voltage control scheme allows incorporating the frequency controller. The distinctive feature of this controller is that it incorporates a bounded integral control strategy that guarantees stability. Results on the stability of the hydropower plant with proposed scheme are presented and robust ways to choose the controller gains are investigated via root locus analysis. Simulations performed show that: the hydropower plant response is significantly improved with battery storage using the proposed scheme; the load carrying capability of the hydropower plant is significantly improved with battery storage; the proposed scheme has the capability to recharge the battery; and the proposed control scheme gives improved performance.
Sustainable development demands no depletion of energy resources that have lower environmental impact, that are available at reasonable costs and that do not have negative social impacts. Because of ...the multi-dimensionality of this sustainable goal multi – criteria methods have become popular in sustainable decision-making processes. In this paper, we have developed a model for decision makers to rank small hydropower projects according to multiple criteria. The proposed model ranks projects based on technical, economic, social, and environmental criteria. The model is supported by two multi-criteria decision analysis methods: PROMETHEE (to rank projects) and Analytic Hierarchy Process (to determine the weights of main criteria). It is observed that the most important criteria are found to be the investment safety, legal obstacles and the amount of flow and the flow pattern. The proposed model is successfully tested on the example of 24 small hydropower plants. Highest ranked projects are those were criterion “annual production” was the highest and with the lowest scores in environmental aspect criteria. The presented model can give objective standpoint to decision makers, energy policies designers and energy planners.
•The model is developed using the combination of two multi-criteria analysis methods (AHP and PROMETHEE).•The model ranks 24 available locations for the construction of small hydropower plants.•The conducted analysis covers economic, technical, environmental and social aspects.•The proposed approach is a useful tool for energy policy designers and energy planners.
Abstract The hydraulic turbine is considered as a heart of the hydropower plant because of its important function in the whole process of electrical energy production. Turbine´s efficiency ...calculation is analytically demanding and dependent on parameters that are often obtained only by a theoretical estimation. Therefore, using its accurate model, which takes into account its efficiency, is necessary to achieve realistic and relevant results. The article briefly surveys current knowledge and methods of designing the hydraulic turbine model. The new idea consists in that a fuzzy system was used to create turbine´s efficiency model based on a measured operating data of the turbine flow rate and its mechanical speed without any need of knowing exactly the turbine parameters. Such a model can be used in the design and development process of an optimal energy control of a hydraulic turbine, as well as in the effective process of determination the actual turbine’s wear rate. The achieved results were obtained using the computational tools of the Fuzzy Toolbox in the MATLAB.
Low-head hydropower bears tremendous potential as a renewable energy source, especially in the context of the progressing global warming. In locations with a low head, for economic and environmental ...reasons, a small hydropower plant with a waterwheel and an asynchronous generator may provide the best solution for sustainable electricity production. The purpose of this study is to demonstrate a new type of low-speed radial piston pump intended to be part of the hydrostatic transmission of such a small hydropower plant. The advantage of the transmission is the possibility of stepless, automatic change of the gear ratio during operation. First, we describe a mathematical model of the proposed pump and subsequently demonstrate a test stand equipped with its prototype with three suction-pressure units. The pump flow rate characteristics calculated using the theoretical model were compared with those obtained from experiments, resulting in the determination and characterization of the pump's efficiency. Supplementary experiments with a hydraulic accumulator installed as part of the investigated system, demonstrated the possibility of flow rate pulsation dampening. The experimental results showed the validity of the developed mathematical model. In conclusion, the correct operation of the pump was corroborated, and its potential application confirmed by the efficiency results.
•The experimental results showed the validity of the developed mathematical model.•The hydraulic accumulator in the system dampens the pump flow rate pulsation.•The highest efficiency of 92.45% is achieved for 8 rpm and 6 MPa output pressure.•Efficiency characteristics of the pump confirm possible application.
The development of efficient energy, water and environment systems is considered a fundamental key to satisfy the principles of cleaner production, energy security and circular economy. The present ...study aims at investigating the possible energy exploitation of the untapped hydraulic potential in collective irrigation systems by adopting pumps as turbines. These machines are not extensively used to produce electricity due to the lack of information in reverse operation mode and the low efficiency outside the best efficiency point. This study proposes new correlation rules to obtain more accurate performance of the pumps as turbines and introduces a novel methodology to select the proper hydraulic machines and define the optimal hydropower configuration. The proposed procedure based on a multi-variable optimisation has been applied to the whole collective irrigation networks of Calabria (Southern Italy). Specifically, the energy production, greenhouse gas emissions and investment costs of 114 potential small hydropower plants have been estimated. The results show that the adoption of pumps as turbines in small-scale hydropower plants is a viable, clean and cheap solution for an extensive use in collective irrigation systems. These machines lead to a noticeable decrease in the electro-mechanical costs (−74%) with only a slight reduction (−19%) in the total electric power compared to specific-site designed turbines. Furthermore, the proposed hydropower systems guarantee a significant fall in greenhouse gas emissions (larger than 8800 tons/year) with respect to the conventional Italian electric production. The generated electricity could be used to satisfy a larger share of electric demand coming from collective irrigation agencies and/or agricultural farms with significant improvements in their economic and environmental impact. Overall, the proposed methodology may represent a valid design tool for an extensive exploitation of hydropower sources in rural water systems, in an effort to enhance cleaner energy productions and integrated systems of energy, water and environment.
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•PATs are used to reduce the installation costs of small hydropower plants (SHPs).•A methodology identifying the proper PAT and the operating conditions is proposed.•The model has been applied to collective irrigation networks of Calabria (Italy).•The adoption of PATs is a viable solution for energy recovery in irrigation systems.•The proposed SHPs provide significant decrease in GHG emissions (−8800 tons/year).
Medium-term forecasting of water inflow is of great importance for small hydroelectric power plants operating in remote power supply areas and having a small reservoir. Improving the forecasting ...accuracy is aimed at solving the problem of determining the water reserve for the future generation of electricity at hydroelectric power plants, taking into account the regulation in the medium term. Medium-term regulation is necessary to amplify the load in the peak and semi-peak portions of the load curve. The solution to such problems is aggravated by the lack of sufficiently reliable information on water inflow and prospective power consumption, which is of a stochastic nature. In addition, the mid-term planning of electricity generation should consider the seasonality of changes in water inflow, which directly affects the reserves and the possibility of regulation. The paper considers the problem of constructing a model for medium-term forecasting of water inflow for planning electricity generation, taking into account climatic changes in isolated power systems. Taking into account the regularly increasing effect of climate change, the current study proposes using an approach based on machine learning methods, which are distinguished by a high degree of autonomy and automation of learning, that is, the ability to self-adapt. The results showed that the error (RMSE) of the model based on the ensemble of regression decision trees due to constant self-adaptation decreased from 4.5 m3/s to 4.0 m3/s and turned out to be lower than the error of a more complex multilayer recurrent neural network (4.9 m3/s). The research results are intended to improve forecasting reliability in the planning, management, and operation of isolated operating power systems.
The operation of water structures causes various problems. They are related, for example, to the material carried by the water, hydrological conditions, range of operation of hydroelectric turbines, ...or water elevations at the lower position of the hydroelectric power plant. Among the various operational problems, this article focuses mainly on the impact of the backwater of Gwda river on the water level elevations at the lower station of the Stary Młyn hydropower plant in Dobrzyca. The power plant is located on Głomia river. The analysis was carried out for different flow variants in both the Gwda and Głomia rivers. The effect of characteristic flows on the water surface level at the lower station of the hydropower plant was examined. It was found that the water surface level at the lower station of the hydropower plant is strongly influenced by flows higher than the average high flow on Gwda river. Due to the extent of the backwater in current operating conditions, the hydroelectric power plant is shut down from flows on Gwda river of 30–28 m3/s (flows that are not much higher than the multi-year average SSQ). The modeling results were confirmed by an analysis of power plant shutdowns of normal operation especially in wet years, when the plant did not operate for almost half of the year (188 days), with losses of 203 MWh. It was also shown that even a small additional damming of water, e.g., of the order of 0.2 m, can extend the operating time of a power plant up to 249 days even under unfavorable hydrological conditions. Factors related to climate change are beginning to play an increasingly important role in the current operating conditions of small lowland hydroelectric power plants. They can contribute to a reduction in electricity production. The proposed solution related to the possibility of greater water retention on dammed-up water barrages allows one to partially offset these problems as well.
Abstract This paper is dedicated to the description of all our research done so far in the field of simulation of small hydropower plants as well as in creating a functional laboratory model based on ...the proposed simulation models. Comparing to the common structures, we propose some different approaches in modelling parts of the small hydropower plants, e.g. fuzzy model of the hydraulic turbine efficiency. Moreover, this simulation model is created directly for the small hydropower plants, thus it simplifies parts, that are commonly used in other scientific papers and simulate the phenomenon connected to the big scale hydropower plants structure and physical description. As a necessary step in the process of creation of universal laboratory model of a small hydropower plant that should be used for design and tuning purposes of new approaches of controlling such systems, we discuss the research and development phase that led to the final construction of the depicted laboratory model.
Small-scale hydropower is a significant source of renewable and inexpensive energy. This study was carried out to identify suitable potential sites for small-scale hydropower for the generation of ...electricity along the Awata River in Ethiopia. Primary and secondary data collected from various sources were used in the present study to achieve its objective. After the consistency of rainfall was checked and areal rainfall was estimated using the Theissen polygon method, the rainfall–runoff relationship was simulated using HEC-HMS. The head of each identified site was estimated by using GIS to overlay the DEM and stream network starting at the outlet. To estimate the discharge, the flow duration curve was developed. HEC-HMS performance was evaluated using Nash–Sutcliffe efficiency (NSE), Mean Absolute Error (MAE), Percent Bias (PBIAS), and coefficient of determination (R2). During calibration, the values were 0.82, 4.39, −2.93, and 0.83, and during validation, the values were 0.76, 5.35, 6.25, and 0.76. The identified sites were ranked using an analytical hierarchy process based on a ratio of five criteria. There are twenty-eight sites identified, with estimated power output and energy output of 45.26 MW and 198.79 GWh at 50% and 6.74 MW and 53.23 GWh at 90%, respectively. The overall rank indicated that the selected site code 29 is ranked first and can be used for the implementation of a small hydropower plant. As a result, the design of all the components of small hydropower plants will be required to implement and generate energy for rural areas in future development.
•An analytical hierarchy process on the GIS was used to evaluate the weight ratio value and prioritize the potential sites.•The Potential site are selected based on discharge, head, energy output, road accessibility, and demand center.•The discharge for each identified site was estimated using the site’s developed flow duration curve.•The overall rank value can help decision makers to implement a sustainable small hydropower project.
A small hydro plant using an Archimedes screw is the focused of this work. This is an alternative solution to smallscale hydropower as it exploits unused resources such as small rivers or streams. ...Archimedes screw plants reverse the pump use principle and exploit the available stream power for energy production in very low head application. Based on the previous studies, the optimal sizing of Archimedes screws is discussed. Then, a numerical model is established to determine the mechanical efficiency according to its geometrical parameters, its rotational speed and its degree of filling. Simulation results are showed and validated with data from a real installation: this work reports experimental results of a 0.84-m diameter Archimedes screw delivering a torque of 250-N-m. This model is an essential part of the whole electromechanical plant modeling and therefore is useful for the estimation of efficiency, energy production and profitability.
•Numerical model is established to determine the mechanical efficiency.•Experimental results of a 0.84 m diamater Archimedes screw.•Simulation results are sufficiently accurate.
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