Hydro/Battery Hybrid Systems for frequency regulation

An innovative Hydro/Battery Hybrid System (HBHS), composed of a hydropower plant (HPP) and a Battery Energy Storage System (BESS) is proposed to provide frequency regulation services in the Nordic Power System (NPS). The HBHS is envisioned to have a faster and more efficient response compared to HPPs currently providing these services, whilst retaining their high energy capacity and endurance, thus alleviating stand-alone BESS operation constraints. This Thesis aims to explore the operation and optimization of such a hybrid system in order to make it efficient and economically viable. A power plant perspective is employed, evaluating the impact different control algorithms and parameters have on the HBHS performance. Providing Frequency Containment Reserves for Normal Operation (FCR-N), to the national TSO in Sweden, is defined from technology and market analyses as the use case for the HBHS. The characteristics of HPPs suitable for HBHS implementation are found theoretically, by evaluating HPP operational constraints and regulation mechanisms. With the aim of evaluating the dynamic performance of the proposed HBHS, a frequency regulation model of the NPS is built in MATLAB and Simulink. Two different HBHS architectures are introduced, the Hydro Recharge, in which the BESS is regulating the frequency and the HPP is controlling its state of charge (SoC), and the Frequency Split, in which both elements are regulating the frequency with the HPP additionally compensating for the SoC. The dynamic performance of the units is qualitatively evaluated through existing and proposed FCR-N prequalification tests, prescribed by the TSO and ENTSO-E. Quantitative performance comparison to a benchmark HPP is performed with regards to the estimated HPP regulation wear and tear and BESS degradation during 30-day operation with historical frequency data. The two proposed HBHS architectures demonstrate significant reductions of estimated HPP wear and tear compared to the benchmark unit. Simulations consistently report a 90 % reduction in the number of movements HPP regulation mechanism performs and a more than 50 % decrease in the distance it travels. The BESS lifetime is evaluated at acceptable levels and compared for different architectures. Two different applications are identified, the first being installing the HBHS to enable the HPP to pass FCR-N prequalification tests. The second application is increasing the FCR-N capacity of the HPP by installing the HBHS. The Frequency Split HBHS shows more efficient performance when installed in the first application, as opposed to the Hydro Recharge HBHS, which shows better performance in the second application. Finally, it is concluded that a large-scale implementation of HBHSs would improve the frequency quality in the NPS, linearly decreasing the amount of time outside the normal frequency band with increasing the total installed HBHS power capacity

Bibliography on the Electrical Aspects of Small Hydro Power Plants

This bibliography is designed to help the reader search for information on some of the electrical aspects of small hydro power plants. The bibliography is intended to help engineers and scientists who may be unfamiliar with this aspect of small hydro, university researchers who are interested in this field, manufacturers who want to learn more about these topics and librarians who provide information to their clients. Topics covered range from the small hydro economic analysis, control and governors, some aspects of hydropower development projects, modeling and simulation studies and future role of small hydro power plants. The references appearing throughout this bibliography do not represent all available material on a specific topic. The inclusion of references in the bibliography is based on several factors, including relevancy to the particular topic, frequency of citation in the professional literature and availability

CFD Modelling and Simulation of Water Turbines

The design and development of water turbines requires accurate methods for performance prediction. Numerical methods and modelling are becoming increasingly important tools to achieve better designs and more efficient turbines, reducing the time required in physical model testing. This book is focused on applying numerical simulations and models for water turbines to predict tool their performance. In this Special Issue, the different contributions of this book are classified into three state-of-the-art Topics: discussing the modelling of pump-turbines, the simulation of horizontal and vertical axis turbines for hydrokinetic applications and the modelling of hydropower plants. All the contributions to this book demonstrate the importance of the modelling and simulation of water turbines for hydropower energy. This new generation of models and simulations will play a major role in the global energy transition and energy crisis, and, of course, in the mitigation of climate change

Numerical and Experimental Investigation of Performance for Very-Low-Head Micro and Pico Kaplan Hydro-Turbines with Rim-Driven Generators

Renewable energy plays a significant role in new power generation worldwide, and hydropower is contributing to 86% of renewable electricity production within all other renewable energy resources. Simultaneously, hydropower shares 83% of U.S. renewable energy capacity and accounts for 77% of actual renewable electricity generation. However, most of the installed hydropower consists of large plants. Much potential hydro generation remains untapped, particularly at lower power and head levels. There is a substantial opportunity worldwide and across the U.S. in specific to add new hydropower generating capabilities at low-head sites such as non-powered dams, canals, and conduits with a water height of less than 30 meters, especially, where the potential of solar and wind is not available. As stated by the U.S. Department of Energy, there is an estimated potential hydropower capacity of 12,000 MW of the existed 80,000 unpowered dams with at least 3 feet of water head available. In this research, investigation of power-efficient micro and pico Kaplan hydro turbines at very-low-head with rim-driven generators to be studied and evaluated, specifically, at heads of less than 3 meters (10 ft). Optimization of performance and design for a 3D-printed conventional -with shaft- 7.6 cm (3-inch) Kaplan turbine to be carried out based on an experimental setup in the Hydro Turbines Laboratory of the University of Wisconsin-Milwaukee in addition to the utilization of Computational Fluid Dynamics (CFD). Then a shaftless rim-driven generator-based turbine (RDT) to be introduced and optimized. Such a new hydro turbine perception will increase the efficiency (of power generation) of hydro turbines in general, and the efficiency of low-head turbines in specific. The design optimization includes; the number of the blades for the turbine’s rotor (runner) and stator, the blade wrap-angle of the rotor, intake and draft tubes angles, lengths and shapes, and the guide vanes. The performance in terms of the power output and the efficiency is evaluated for the conventional turbine by utilizing CFD and by testing a 3D-printed model of the turbine in a custom-built experimental setup at different water heads (from 2.0 m to 2.6 m) and different rotational speeds (0 – 4000 rpm). The CFD setup is based on 3D transient turbulent featuring the Large Eddy Simulation (LES) model, and STAR-CCM+ is the CFD software. In addition, the high-performance computing (HPC) cluster of the University of Wisconsin-Milwaukee is used for solving the complex CFD simulations. To evaluate the advantage of the RDT over the conventional turbines, the rim-driven shaftless turbine is introduced in this research at the same boundary conditions. The RDT is not expected only to increase the efficiency of hydro turbines. It will also contribute saving the environment by allowing debris or fish to pass through the central area of the turbine, especially in the case of run-a-river hydro turbines applications. Furthermore, some applications of the RDT are presented in this study. The utilization of RDT in wastewater treatment plants (WWTPs) is one example where WWTPs usually have low or very-low head between the discharge point of the plant and the water body where the treated water is supposed to be disposed. At the same time, a significant continuous water flow rate is available all over the year for feasible hydro turbine installations. Such utilization will improve the energy efficiency of WWTPs

Advancements in Hydropower Design and Operation for Present and Future Electrical Demand

With current infrastructure, meeting the ever-growing demand for electrical energy across the globe is becoming increasingly difficult. The widespread adoption of both commercial and residential non-dispatchable renewable energy facilities, such as solar and wind, further taxes the stability of the electrical grid, often causing traditional fossil fuel power plants to operate at lower efficiency, and with increased carbon emissions. Hydropower, as a proven renewable energy technology, has a significant part to play in the future global electrical power market, especially as increasing demand for electric vehicles will further amplify the need for dispatchable energy sources during peak charging times. Even with more than a century of proven experience, significant opportunities still exist to expand the worldwide hydropower resources and more efficiently utilize existing hydropower installations. Given this context, this Special Issue of Energies intended to present recent developments and advancements in hydropower design and operation. This Special Issue includes five articles, authored by international research teams from Japan, Pakistan, Sweden, Norway, the United States, and China. The authors bring the collective expertise of government research laboratories, university professors, industry research engineers, computer scientists, and economists. The articles explore advancements in hydroturbine and pump-turbine design, power plant operation, auxiliary equipment design to mitigate environmental damage, and an exploration of community-owned small hydropower facilities

Stability Analysis of a Run-of-River Diversion Hydropower Plant With Surge Tank And Spillway in the Head Pond

Run-of-river hydropower plants usually lack significant storage capacity; therefore, the more adequate control strategy would consist of keeping a constant water level at the intake pond in order to harness the maximum amount of energy from the river flow or to reduce the surface flooded in the head pond. In this paper, a standard PI control system of a run-of-river diversion hydropower plant with surge tank and a spillway in the head pond that evacuates part of the river flow plant is studied. A stability analysis based on the Routh-Hurwitz criterion is carried out and a practical criterion for tuning the gains of the PI controller is proposed. Conclusions about the head pond and surge tank areas are drawn from the stability analysis. Finally, this criterion is applied to a real hydropower plant in design state; the importance of considering the spillway dimensions and turbine characteristic curves for adequate tuning of the controller gains is highlighte

Instabilities and Influence of Geometric Parameters on the Efficiency of a Pump Operated as a Turbine for Micro Hydro Power Generation: A Review

Compared to a traditional turbine (Kaplan, Francis, Pelton), pumps operated as turbine are a good alternative for micro hydroelectric power plants thanks to their low cost and easy availability. This paper presents a review of the most challenging aspects of the pump as turbine: prediction and improvement in turbine mode. First, an explanation of the theory of the pump as turbine focused on the functioning, types of pumps, selection criteria and performance predictions as shown in the literature, giving also methodologies and details on the pump as turbine selection. Afterwards, the literature shows the instabilities produced by the operation of the pumps on inverse mode, which generates S-shape curves and cavitation. Finally, as the main focus of this paper, aspects of efficiency produced by geometric parameters were discussed. Current trends and future scope for further improvement and implementation of pump as turbine are also discussed