Hydroelectric System Research Articles

Potential and Feasibility Study of Hybrid Wind–Hydroelectric Power System with Water-Pumping Storage: Jordan as a Case Study

Periodic daily fluctuating demand for energy and power is a perceptible phenomenon, resulting in some moments of low demand for power and energy related to the huge energy comes from renewable energy systems, and some moments of peak load demand. This phenomenon, when combined with the non-stationary operation of huge capacity of renewable energy systems, results in no stability of voltage and frequency. To assure continuous network stability and to avoid energy losses from renewable energy systems that are subject to such control system, a hybrid system with energy–power storage in the form of pumped-hydro storage is considered the most suitable technically. This paper presents the design, modeling, analysis, and feasibility study of a hybrid wind and water-pumping storage system. The system was designed and analyzed for King Talal Dam (KTD), which is in Northern Jordan. The importance of this study is that it is directed mainly to Jordan and the Middle East and North Africa (MENA) region in general. The Jordanian renewable energy market is a promising arena that encourages developers, investors, engineers, and companies to develop and install pure renewable energy systems and renewable energy hybrid projects for the generation of electricity. The analysis of wind data is carried out using the “windfarm” software with 5.16 m/s as average wind speed. It is followed by the design of the hybrid system, which is simulated for a daily operation of 2–3 h as peak load hours. Based on the technical outcomes, cost study and feasibility analyses are carried out with Jordanian market prices. The total estimated annual energy production is 26,663,933 kWh from 10 MW wind farm and 5.2 MW pumping storage system. The aforementioned studies showed that a similar hybrid system is not always fully commercially feasible. However, a pure pumped-storage system proved to be technically feasible and assisting the grid. The whole project analysis determines that such a system boosts the operational stability of the grid, increases the penetration of renewable energy systems and reduces the energy import. In addition, 15,100,000 tons of CO2-equivalent is estimated as annual emissions reduction in this study.

ОБОСНОВАНИЕ ЦЕЛЕСООБРАЗНОСТИ СУТОЧНОГО РЕГУЛИРОВАНИЯ СТОКА НИЗКОНАПОРНЫМ ГИДРОУЗЛОМ

The article considers possible problems for shipping, which may arise after the construction and commissioning of the Nizhny Novgorod low-pressure hydroelectric complex. By analyzing the available data on the change in navigation expenses through the Nizhny Novgorod hydroelectric power station and the predicted calculation of the water regime in the alignment of the created Nizhny Novgorod low-pressure hydroelectric system, it is ascertained in the article whether the navigable dimensions in depth are ensured in the section above and below the alignment of the NNSU during the navigation period. In order to determine the possibility of regulating runoff on a spillway of the Nizhny Novgorod State University, an experiment is set up at the Volga State Unversity of Water Transport laboratory, during which the speed and time parameters of the water flow are established. The article presents the results of the work.

Transient safety assessment and risk mitigation of a hydroelectric generation system

Transient safety assessment of hydroelectric generation systems is a major challenge for engineers specialized in hydropower stations around the world. This includes two key scientific issues: the dynamic risk quantification in a multi-factors coupling process, and the identification of elements with highest contribution to system stability. This paper presents a novel and efficient dynamic safety assessment methodology for hydroelectric generation systems (HGSs). Based on a comprehensive fuzzy-entropy evaluation method, the dynamic safety level of the system is estimated by means of probability values, and the influence rate of assessment indices on the HGS risk profile is also obtained. Moreover, a number of risk mitigation and maintenance amendment strategies are discussed to reduce the losses in operation and maintenance (O&M) costs at hydropower stations. The methodology is implemented and validated using an existing hydropower station experiencing a start-up transient process, results of which are shown to be beneficial to operators and risk managers. It is recommended that the presented methodology is applicable not only to the HGS’s start-up process but is also promisingly useful for largely fluctuating transient processes of other engineering facilities.

Multi-objective optimal operation of coastal hydro-electrical energy system with seawater reverse osmosis desalination based on constrained NSGA-III

To make best use of available coastal renewable energy and to meet local freshwater demand, optimal operation of a coastal hydro-electrical energy system with consideration of seawater desalination is proposed in this paper. The paper outlines a system configuration which is used to develop the virtual energy storage characteristics of a desalination plant and in which cost-savings are demonstrated while preserving the local desalinated water supply. To achieve the control criteria, minimization of the total period cost and tie-line power fluctuations are considered as two objectives in an objective function. Constraints are established based on the system configuration and the multi-objective optimization problem is solved with the third generation of the constrained non-dominated sorting genetic algorithm (NSGA-III) algorithm. Virtual energy storage characteristics of the desalination units is studied and utilized in the model. The paper examines several case studies to verify the feasibility and merits of the proposed method. The operational characteristics of the virtual energy storage components in the system is discussed, and sensitivity analysis of the operating parameters of the pumped storage hydropower unit and the seawater desalination unit are also conducted. Simulation results show that the proposed optimal operation approach is suitable for calculating the total cost as well as assessing the power stability on the tie-line, and NSGA-III is capable of determining the Pareto-optimal operational plans of the system.

Finite element modelling of an energy-geomembrane underground pumped hydroelectric energy storage system

The increasing need for energy storage technology has led to a massive interest in novel energy storage methods. The energy geomembrane system is such a novel energy storage method. The concept of the system is briefly introduced, and a holistic numerical model of the system is presented. The model uses advanced finite-element techniques to model the energy storage system using fluid cavity elements. The developed geomembrane energy system is modelled with different constitutive models to represent the soil behaviour: a linear elastic model, a nonlinear Mohr-Coulomb model, and a hypoplastic constitutive model. The consequences of these different models on the results are studied. Hereby, the focus is the first inflation and deflation cycle of the system.

Analysis of Mode Interaction in Ultra-low Frequency Oscillation Based on Trajectory Eigenvalue

Complex phenomena such as prolongedly undamped ultra-low frequency oscillation (ULFO) and eigenmode re-excitation are observed in the simulations of hydroelectric power systems. Emphases are put on nonlinearities and mode interactions, which cannot be analyzed by traditional eigen-analysis methods. In order to investigate the mechanism of the evolvement of the nonlinear dynamic process in ULFO, this paper proposes a method to analyze the mode interactions quantificationally. First, a disturbed trajectory is decoupled into a set of time-varying components. Second, transfer matrices of eigenmodes are extracted along the trajectory. Third, consecutive sequences of eigenvalues and trajectories of components are formed by a proposed technique. Based on the decoupled components and transfer matrices, the mechanisms of mode interactions and inheritance relationships between eigenmodes are analyzed. The causes and developments of the above complex phenomena are revealed by the proposed method in a test two-machine system. Meanwhile, the accuracy of the eigenmode matching technique is verified in the New England system.

Comprehensive Review of Pump as Turbine

The turbine is a heart of power generation in a hydro-electric power system. A variety of different turbines are available for the purpose. The common types of Hydraulic turbines are; Pelton, cross flow, Francis, Kaplan, and propeller turbine. However, using conventional turbines for low head and flow rate (i.e. micro hydropower) applications is not economically feasible. A low-cost alternative is to use pump as turbine. In this paper, collect and review existing Pear reviewed articles from (Scopus, google scholar, umbrella, etc.) that are directly related to pump running as a turbine from the year (2014 to 2019). Theoretical, numerical, and experimental investigations are considered. Performance improvement techniques for PAT are summarized and research gaps in related works are identified.

Hybrid Energy System with an Energy Management Control Strategy Based on the Online Fuel Consumption

Many agriculture investments are oriented to the Sahara. Noticeably, they need electricity which is often provided by diesel generators. The refueling process is a real economic challenge due to the very remote area distance which makes it very expensive. To overcome this issue, the hybridization is initiated with the renewable solar photovoltaic energy. That marks an excess or a shortage of power; to cope this uncontrolled power a storage system is compulsory. This work is specific to the pumped hydroelectric storage system which is favorable due to its ecological aspects and the subject matter. The proposed management takes into account the solar temporal variation combined to the pumping scheduling time and real-time fuel consumption optimization. This last proves the PSH’s performance dual function in both the irrigation and power restitution; it also reduces the gas emission and saves fuel. As far as this study is concerned, the suggested control is successfully examined through the management strategy in comparison to that of the literature. Consequently, this study could be helpful for similar future studies. Because, it links the diesel efficiency, solar variation, and dynamic load under the constraints of diesel rated power optimal sizing, PV panels surface, and water tank dimension.

Conventional hydroelectricity and the future of energy: Linking national inventory of dams and energy information administration data to facilitate analysis of hydroelectricity

Within the energy community, conventional dam and reservoir-based hydroelectricity is often viewed as a low-cost, immediately available zero-carbon resource that could facilitate more intermittent renewable electricity integration, seasonal storage, and other grid benefits. Conventional hydroelectricity systems, however, are potentially unique among power plants in that energy provisioning is not the only priority for their fuel, stored water. This paper presents a record linkage between electricity- and dam management-oriented datasets to facilitate attention to the fundamental challenge of altering operational regimes for systems that have other uses.

Time Series Analysis for Predicting Hydroelectric Power Production: The Ecuador Case

Electrical generation in Ecuador mainly comes from hydroelectric and thermo-fossil sources, with the former amounting to almost half of the national production. Even though hydroelectric power sources are highly stable, there is a threat of droughts and floods affecting Ecuadorian water reservoirs and producing electrical faults, as highlighted by the 2009 Ecuador electricity crisis. Therefore, predicting the behavior of the hydroelectric system is crucial to develop appropriate planning strategies and a good starting point for energy policy decisions. In this paper, we developed a time series predictive model of hydroelectric power production in Ecuador. To this aim, we used production and precipitation data from 2000 to 2015 and compared the Box-Jenkins (ARIMA) and the Box-Tiao (ARIMAX) regression methods. The results showed that the best model is the ARIMAX (1,1,1) (1,0,0)12, which considers an exogenous variable precipitation in the Napo River basin and can accurately predict monthly production values up to a year in advance. This model can provide valuable insights to Ecuadorian energy managers and policymakers.

Movements, habitat use, and entrainment of stocked juvenile lake sturgeon in a hydroelectric reservoir system

Identifying movement and habitat use patterns is essential for fish passage efforts and the conservation of threatened species. We used acoustic telemetry to track the movements of 44 juvenile lake sturgeon (Acipenser fulvescens) throughout Kleber Reservoir in northern Michigan. On average, lake sturgeon moved 502 m between telemetry positions, with age-2 lake sturgeon moving longer distances than age-1 lake sturgeon. Areas with high numbers of lake sturgeon detections were clustered near the forebay, while zones with low numbers of detections were clustered toward the head of the reservoir. Analyses showed that 66.4% of the variance in habitat use could be explained by physical habitat features. Reservoir areas with ample deepwater habitat, fine soft substrates, and limited macrophyte vegetation were the most frequently occupied and, thus, may provide suitable habitat conditions to support juvenile lake sturgeon. We observed that 54.4% of the age-1 and 52.8% of the age-2 lake sturgeon stocked into Kleber Reservoir were entrained. Reservoir size, morphology, and the location of suitable habitat in relation to hydroelectric infrastructure may be key factors that affect entrainment rates.

Sediment Erosion Characteristics and Mechanism on Guide Vane End-Clearance of Hydro Turbine

Sediment erosion caused by the collision of solid particles is a challenge for the safety, reliability, unit efficiency, and vibration noise of the hydroelectric engineering system located at China’s Yellow River and northwest inland basin. The sediment-laden flow of the guide vane end-clearance of the Francis Turbine at Dongshuixia hydroelectric station was used as the research object, and the large eccentric shaft structure of a guide vane was considered. Numerical calculations with the large eddy simulation (LES) and discrete phase models (DPMs) were carried out to study the erosion characteristics and mechanism of the end-surface of the guide vane and head cover, the flow mechanism of adverse erosion behind the shaft, and the influence law of the turbulence integral scale, turbulent kinetic energy, and turbulent flow angle on erosion. The flow field with a 1 mm clearance should set the number of particle trajectory per unit inlet area at about 1/mm2 to ensure the accuracy of calculation. The von Kármán vortex street is the main reason for adverse erosion behind the shaft and the low frequency energy of the turbulence plays a leading role in erosion. The above results provide a reference for the optimization design of an anti-wear guide vane and wear-protection of the clearance with sediment-laden water.

Optimal Short-Term Operation of a Cascaded Hydro-Solar Hybrid System: A Case Study in Kenya

In this paper, we propose an optimal dispatch scheme for a cascaded hybrid hydro-solar power system, i.e., a hydroelectric system coupled with solar generation, which maximizes the head levels of each dam, and minimizes the spillage effects. As a result, more water is stored in the dams to meet a given amount of energy providing more flexibility to the system in dry months. This dispatch scheme is based on the development of a simplified hydroelectric power system model, which has low computational burden and may be implemented for the short-term operation of a cascaded hydro-solar hybrid power system. To this end, the non-convex relationships that describe the system physical constraints, e.g., hydroelectric power output, are transformed into affine relationships; thus, reducing the computational complexity. The transformations are based on the construction of convex envelopes around bilinear functions, piecewise affine functions, and exploitation of optimization properties. We validate the proposed framework and quantify the benefits of coupling hydroelectric and solar resources in terms of live water volume in dams and amount of solar a system may withstand with the Tana river cascade located in Kenya through an analysis of incorporating actual system data.

Short-term optimal hydro-thermal scheduling using clustered adaptive teaching learning based optimization

<span>In this paper, Clustered Adaptive Teaching Learning Based Optimization (CATLBO) algorithm is proposed for determining the optimal hourly schedule of power generation in a hydro-thermal power system. In the proposed approach, a multi-reservoir cascaded hydro-electric system with a non-linear relationship between water discharge rate, net head and power generation is considered. Constraints such as power balance, water balance, reservoir volume limits and operation limits of hydro and thermal plants are considered. The feasibility and effectiveness of the proposed algorithm is demonstrated through a test system, and the results are compared with existing conventional and evolutionary algorithms. Simulation results reveals that the proposed CATLBO algorithm appears to be the best in terms of convergence speed and optimal cost compared with other techniques.</span>

Carbon dioxide (CO<sub>2</sub>) concentrations and emission in the newly constructed Belo Monte hydropower complex in the Xingu River, Amazonia

Abstract. The Belo Monte hydropower complex located in the Xingu River is the largest run-of-the-river (ROR) hydroelectric system in the world and has one of the highest energy production capacities among dams. Its construction received significant media attention due to its potential social and environmental impacts. It is composed of two ROR reservoirs: the Xingu Reservoir (XR) in the Xingu's main branch and the Intermediate Reservoir (IR), an artificial reservoir fed by waters diverted from the Xingu River with longer water residence time compared to XR. We aimed to evaluate spatiotemporal variations in CO2 partial pressure (pCO2) and CO2 fluxes (FCO2) during the first 2 years after the Xingu River impoundment under the hypothesis that each reservoir has contrasting FCO2 and pCO2 as vegetation clearing reduces flooded area emissions. Time of the year had a significant influence on pCO2 with the highest average values observed during the high-water season. Spatial heterogeneity throughout the entire study area was observed for pCO2 during both low- and high-water seasons. FCO2, on the other hand, only showed significant spatial heterogeneity during the high-water period. FCO2 (0.90±0.47 and 1.08±0.62 µmol m2 d−1 for XR and IR, respectively) and pCO2 (1647±698 and 1676±323 µatm for XR and IR, respectively) measured during the high-water season were on the same order of magnitude as previous observations in other Amazonian clearwater rivers unaffected by impoundment during the same season. In contrast, during the low-water season FCO2 (0.69±0.28 and 7.32±4.07 µmol m2 d−1 for XR and IR, respectively) and pCO2 (839±646 and 1797±354 µatm for XR and IR, respectively) in IR were an order of magnitude higher than literature FCO2 observations in clearwater rivers with naturally flowing waters. When CO2 emissions are compared between reservoirs, IR emissions were 90 % higher than values from the XR during low-water season, reinforcing the clear influence of reservoir characteristics on CO2 emissions. Based on our observations in the Belo Monte hydropower complex, CO2 emissions from ROR reservoirs to the atmosphere are in the range of natural Amazonian rivers. However, the associated reservoir (IR) may exceed natural river emission rates due to the preimpounding vegetation influence. Since many reservoirs are still planned to be constructed in the Amazon and throughout the world, it is critical to evaluate the implications of reservoir traits on FCO2 over their entire life cycle in order to improve estimates of CO2 emissions per kilowatt for hydropower projects planned for tropical rivers.

Development and optimization of low-speed and high-efficiency permanent magnet generator for micro hydro-electrical generation system

In this paper, a low-speed and high-efficiency permanent magnet generator (LHPM generator) for micro hydro-electrical generation system was developed, and two different low-speed generators by using silicon steel and SPCC core (Common Cold Steel Plate) were fabricated and compared. The proposed LHPM generator can have high no-load electromotive force (EMF) and high efficiency at low speed by optimizing its parameters, and shows possibility to reduce its production cost by comparing the performance with different ferromagnetic materials of iron cores. Firstly, the principle of the low-speed and high-efficiency permanent magnet generating system was introduced, and the parameter design of the LHPM generator was proposed. Then the performance with different ferromagnetic materials of cores was analyzed. Finally, various Finite Element Analysis (FEA) simulation, optimization studies and experiments were performed. The cogging torque reduction method, effect of PM’s parameters, and the influence of different materials of cores were also investigated. Furthermore, as a tradeoff between the generator’s performance and the production cost, so-called hybrid core type generator, of which the rotor is made of SPCC core and the stator is made of silicon steel core was proposed. The simulation and experimental results demonstrate the effectiveness of the proposed structure.

Towards modelling diffusion mechanisms for sustainable off-grid electricity planning

The electrification-based literature reports a limited knowledge about the mechanisms of evolution of electricity demand in off-grid settings, especially in remote contexts of developing countries, due to the lack of robust and appropriate modelling frameworks. Such lack of understanding and modelling endeavour contributes to an inefficient allocation of resources for electrification projects and inappropriate off-grid sizing processes. As a first step towards the development of a more appropriate electricity demand model, we present a comparative study of two approaches for modelling different diffusion mechanisms of electricity connections: system-dynamics and agent-based models. The latter includes the modelling of social network archetypes in the simulation of diffusion processes. We model different scenarios of diffusion and we use them for evaluating the impact on the sizing process of an off-grid hydroelectric system. The results suggest that the structure of the social network can represent a crucial parameter that can impact on timing needed to complete the diffusion of electricity access – from few months to even >10 years. This affects the sizing process and the long-term sustainability of the power system, leading to variation of the hydroelectric capacity and the battery size up to around 55% and 100%, respectively. Our results indicate that the agent-based approach allows a more diversified representation of diffusion processes, but the limitations and scarcity of data can be an obstacle to their prompt application for energy application in unelectrified areas. On the contrary, system-dynamics can represent a more appropriate method since it requires less quantitative data and it provides a more structural and holistic modelling framework for conceptualising and formulating in a the determinants and complexities affecting the evolution of electricity demand in unelectrified areas.

Stochastic energy investment in off‐grid renewable energy hub for autonomous building

This study forms and optimises the renewable energy hub to supply load demand in the autonomous building disconnected from electrical grid (i.e. net-zero energy building). The proposed energy hub is made of hybrid wind-solar-hydro generation systems and it is also strengthened by pumped-storage hydroelectricity and hydrogen storage systems. The hydro system includes two water reservoirs in cascade connection and one pumped-storage hydroelectricity. The introduced optimisation programming designs proper capacity for cascade water reservoirs and energy storage system as well as optimises their operation. The uncertainties of parameters are included to make the stochastic programming. It is demonstrated that increasing the flow-in of reservoir 1 by 25% decreases the planning cost by ∼2.5% and decreasing the flow-in of reservoir 2 by 50% increases the planning cost by ∼16%. When the hydro system does not operate, the wind power must be increased to 10 kW in order to supply the load. When the wind and solar powers are not integrated, the hydro energy must be increased by 50%.

Bayesian network approach to fault diagnosis of a hydroelectric generation system

AbstractThis study focuses on the fault diagnosis of a hydroelectric generation system with hydraulic‐mechanical‐electric structures. To achieve this analysis, a methodology combining Bayesian network approach and fault diagnosis expert system is presented, which enables the time‐based maintenance to transform to the condition‐based maintenance. First, fault types and the associated fault characteristics of the generation system are extensively analyzed to establish a precise Bayesian network. Then, the Noisy‐Or modeling approach is used to implement the fault diagnosis expert system, which not only reduces node computations without severe information loss but also eliminates the data dependency. Some typical applications are proposed to fully show the methodology capability of the fault diagnosis of the hydroelectric generation system.

Contrasting methane emissions from upstream and downstream rivers and their associated subtropical reservoir in eastern China

Subtropical reservoirs are an important source of atmospheric methane (CH4). This study investigated the spatiotemporal variability of bubble and diffusive CH4 emissions from a subtropical reservoir, including its upstream and downstream rivers, in eastern China. There was no obvious seasonal variation in CH4 emissions from the main reservoir, which increased slightly from the first half year to the next half year. In the upstream river, CH4 emissions were low from February to June and fluctuated widely from July to January due to bubble activity. In the downstream river, CH4 emissions were lowest in February, which was possibly influenced by the low streamflow rate from the reservoir (275 m3 s−1) and a short period of mixing. There was spatial variability in CH4 emissions, where fluxes were highest from the upstream river (3.65 ± 3.24 mg CH4 m−2 h−1) and lowest from the main reservoir (0.082 ± 0.061 mg CH4 m−2 h−1), and emissions from the downstream river were 0.49 ± 0.20 mg CH4 m−2 h−1. Inflow rivers are hot spots in bubble CH4 emissions that should be examined using field-sampling strategies. This study will improve the accuracy of current and future estimations of CH4 emissions from hydroelectric systems and will help guide mitigation strategies for greenhouse gas emissions.