Hydroelectric Power

China has a vast scale of hydropower, and the small hydropower stations account for a large proportion. In flood season, the excessive inflow keeps these stations at a high reservoir level, leading to a worse condition of hindered power output and a great error in the calculation of power generation. Therefore, this paper proposes a mid-term optimal scheduling model for low-head cascaded hydropower stations considering inflow unevenness, in which the power output is controlled by the expected power output curve and daily inflow–maximum power output curve. A case study of nine hydropower stations on the Guangxi power grid shows that, regardless of considering the fitted curve or not, there are different degrees of error between the planned and actual situations. However, the error and power generation are decreased when considering the fitted curve, which reflects the impact of hindered power output. Meanwhile, according to the comparison, the weekly plan is more in line with the real condition when using this model to solve the problem. The results indicate that this model improves the accuracy of power output calculation for low-head hydropower stations with uneven inflow, playing a key role in the process of scheduling. Full article

The recent energy shortfall in Pakistan has prompted the need for the development of hydropower projects to cope with the energy and monetary crisis. Hydropower in the northern areas is available yet has not been explored too much. Focusing on the sustainable development goal (SDG) “Ensure access to affordable, reliable, sustainable and modern energy”, thirteen proposed sites were selected from upstream to downstream of the Hunza River for analysis. The head on all the proposed sites was determined by taking the elevation difference between the proposed turbine and the intake at all sites. The discharge on all proposed ungauged sites was determined using ArcGIS for watershed delineation and the area ratio method along with Soil Conservation Service–Curve Number (SCS-CN) by using gauged data of Hunza River provided by Water and Power Development Authority (WAPDA) Pakistan at Daniyor bridge Gilgit, Shimshal and the Passo tributaries of Hunza River. The Location Search Algorithm (LSA) approach used a multi-criteria decision-making tool (MDM) to make a decision matrix considering the location and constraint criteria and then normalizing the decision matrix using benefit and cost criteria, the relative weights were assigned to all criteria using a rank sum weighted method and the sites were ranked on the basis of the final score. The results revealed that Hunza River has a significant hydropower potential and based on the final score in the LSA approach, proposed site 13, site 4 and site 9 were concluded as the most promising sites among proposed alternatives. The proposed methodology could be an encouraging step for decision makers for future hydropower development in Pakistan. Full article

With the rapid development of artificial intelligence, machine vision and other information technologies in the construction of smart power plants, the requirements of power plants for the state monitoring of hydro-generator units (HGU) are becoming higher and higher. Based on this, this paper applies YOLOv5 to the state monitoring scenario of HGU, and proposes a method for rotor speed measurement (RSM) and operating state identification (OSI) of HGUs based on the YOLOv5. The proposed method is applied to the actual RSM and OSI of HGUs. The experimental results show that the Precision and Recall of the proposed method for rotor image are 99.5% and 100%, respectively. Compared with the traditional methods, the online image monitoring based on machine vision not only realizes high-precision RSM and the real-time and accurate determination of operating states, but also realizes video image monitoring of the rotor, the operation trend prediction of the rotor and the early warning of abnormal operating states, so that staff can find the hidden dangers in time and ensure the safe operation of the HGU. Full article

The Alaska Railbelt transmission system runs from Fairbanks to Anchorage to Homer and supplies 75% of the state’s population with power. In the near future, this system will experience significant increases in load due to electrification of the transportation and heating sectors. To account for this, several state organizations are working towards the creation of an integrated resource plan and reliability standards.This work encompasses the efforts of researching the operations, cost, and locations of desirable hydropower and pumped storage hydropower (PSH) resources in the areas surrounding the Railbelt transmission system. The aspects of conventional hydropower and PSH as well as adjustable-speed and ternary PSH were analyzed. With Alaska’s diverse and rugged landscape, QGIS was utilized to delineate the positions of energy resources within a reasonable distance from the Railbelt. By incorporating Digital Terrain Models and the QGIS processing toolbox, a least cost path analysis was completed to filter out resources within the designated distance of the Railbelt. Applying existing cost models to the data in this work helped to decide the energy resources that would be studied further. The future of this project includes modeling the selected energy sources in the PSS/e Railbelt model to examine their effects on the reliability and stability. Full article

The optimal scheduling of cascade reservoirs is an important water resource management and regulation method. In the actual operation process, its nonlinear, high-dimensional, and coupled characteristics become increasingly apparent under the influence of multiple constraints. In this study, an integrated multistrategy particle swarm optimization (IMPSO) algorithm is proposed to realize the optimal operation of mid- and long-term power generation in cascade reservoirs according to the solution problem in the scheduling process of cascade reservoirs. In IMPSO, a variety of effective improvement strategies are used, which are combined with the standard PSO algorithm in different steps, among which beta distribution initialization improves population diversity, parameter adaptive adjustment accelerates convergence speed, and the Lévy flight mechanism and adaptive variable spiral search strategy balance the global and local search capabilities of the algorithm. To handle complex constraints effectively, an explicit–implicit coupled constraint handling technique based on constraint normalization is designed to guide the update process into the feasible domain of the search space. The feasibility of the proposed method is verified in the mid- and long-term power generation optimization scheduling of the lower reaches of the Jinsha River–Three Gorges cascade hydropower reservoirs. The results show that the proposed method outperforms the other methods in terms of search accuracy and has the potential to improve hydropower resource utilization and power generation efficiency significantly. Full article

Hydropower has grown to play an important role in power systems including increasing clean and low-carbon energies, and the effect of electric loads should be basically evaluated for the reliable operation of these systems. For the hydraulic–mechanical–electrical system of the hydropower station, the state equation model for stability evaluation was derived with typical electric load models and elastic models for pipe flow, and after experimental confirmation with a built single-unit setup for a system, the effects of different electrical loads and pipe flow models on typical hydropower systems stability were investigated in detail. The results indicate that for the built single-unit system with different load characteristics, the numerical results were basically consistent with experimental research, and the unit’s regulation performance for the dynamic load was superior to that of the static load. Evident differences existed in the effects of different electric loads on the operational stability, mainly depending on the pipe length and the corresponding models, and an optimum-order elastic model of pipe flow was preferred to reveal the dynamic interactions between different systems. Furthermore, for a typical two-unit system, the potential coupling resonance hydraulic–mechanical–electrical system is pointed out with the preferred-order elastic model of pipe flow. Full article

Streamflow forecasts from continental to global scale hydrological models have gained attention, but their performance against operational forecasts at local to regional scales must be evaluated. This study assesses the skill of medium-range, weekly streamflow forecasts for 147 large Brazilian hydropower plants (HPPs) and compares their performance with forecasts issued operationally by the National Electric System Operator (ONS). A continental-scale hydrological model was forced with ECMWF medium-range forecasts, and outputs were corrected using quantile mapping (QM) and autoregressive model approaches. By using both corrections, the percentage of HPPs with skillful forecasts against climatology and persistence for 1–7 days ahead increased substantially for low to moderate (9% to 56%) and high (72% to 94%) flows, while using only the QM correction allowed positive skill mainly for low to moderate flows and for 8–15 days ahead (29% to 64%). Compared with the ONS, the corrected continental-scale forecasts issued for the first week exhibited equal or better performance in 60% of the HPPs, especially for the North and Southeast subsystems, the DJF and MAM months, and for HPPs with less installed capacity. The findings suggest that using simple corrections on streamflow forecasts issued by continental-scale models can result in competitive forecasts even for regional-scale applications. Full article

Many issues with water quality and water ecology are caused by the Xinghai Lake’s enormous catchment, significant evaporation rates, and one additional water supply. To quantitatively study Xinghai Lake’s water displacement characteristics, a two-dimensional hydrodynamic-tracer coupling model based on MIKE21 was developed. The findings indicate that: (1) Xinghai Lake’s water replacement cycle exhibits spatial heterogeneity, with a general characteristic of fast water renewal in the southern lake area and slow renewal in the northern lake area, and the gradient change of the water replacement cycle from south to north is influenced by a variety of factors, including the lake’s flow field, flow, topography, and wind field. (2) The throughput flow has an impact on the majority of the waters in Xinghai Lake. When there is a high water flow, the lake region has a high flow velocity, rapid water transport, and a large capacity for water exchange; when there is a low water flow, the lake area has a slow flow velocity, poor water flow, and a lengthy water exchange period. (3) The flow field of Xinghai Lake is complicated, the flow velocity is low, and it is a lake system where quick water exchange and slow water exchange coexist. This flow field is influenced by the interplay of wind-generated flow and throughput flow. (4) To speed up the water body’s rejuvenation, the Xinghai Lake wetland needs more inlets and exits to introduce new water sources. Full article

This study aimed to present the experimental results of two types of turbines and attachments used in a hydro-compact generator. Two Horizontal Spiral Turbines (HSTs) with blade angles of eighteen and twenty-one degrees, respectively, and a three-blade turbine were tested and experimented in a laboratory at five levels of water flow rate ranging from 1–2 m/s. After the efficiency and torque values of each turbine were identified, they were installed in two 200 W power generator systems: (1) with a “diffuser” attachment; and (2) with an “in-line+diffuser+nozzle chamber” attachment, and tested in a local irrigation canal with 1.2 m/s. The results from the laboratory indicated that the HST with a twenty-one degree blade angle had 38.10% efficiency at the water flow rate of 2 m/s. It could reach 120.0 rpm and produced 212 Nm of torque. The results from the field experiment revealed that the combination of the power generator with the twenty-one degree blade angle HST and the in-line + diffuser + nozzle chamber attachment was the most efficient, with 284 Nm of torque at 108 rpm and could generate 67.63 W of electrical power. When the water flow rate of the irrigation canal reached 1.5 m/s, it could reach 114 rpm and generate 129.2 W. This hydro-compact generator set is suitable for irrigation canals with a water flow rate ranging from 1–1.5 m/s. Full article

This study approaches cyber security in industrial environments focusing on hydro power plants, since they are part of the critical infrastructure and are the main source of renewable energy in some countries. The theoretical study case follows the standard IEC 62443-2-1 to implement a cyber security management system (CSMS) in a hydro power plant with two generation units. The CSMS is composed of six steps: (1) initiate CSMS, (2) high level risk assessment, (3) detailed risk assessment, (4) establish policies, procedures, and awareness, (5) select and implement countermeasures, and (6) maintain the CSMS. To perform the high-level risk assessment, an overview of the most common activities and vulnerabilities in hydro power plants systems is presented. After defining the priorities, the detailed risk assessment is performed based on a HAZOP risk analysis methodology focusing on hackable digital assets (cyber-HAZOP). The analysis of the cyber-HAZOP assessment leads to mitigations of the cyber risks that are addressed proposing modifications in the automation architecture, and this also involves checking lists to be used by the stakeholders during the implementation of the solution, emphasizing security configurations in digital assets groups. Full article

Lubricant oil is used in hydropower units to minimize friction, improving the turbine efficiency and reducing the wear. However, oil production is a pollutant process, while eventual spills may affect water quality and damage freshwater ecosystems. In this study, the lubricant oil consumption of the European hydropower fleet was estimated (considering its installed capacity of 254 GW). The energy required to extract and process the oil was also estimated based on available literature data. The oil consumption was estimated to be 22 × 10³ tons/year, and the associated CO₂ emissions are 10⁵ tons/year. The lubricant oil costs EUR 116 million per year. Although this is only 0.0022% of the oil consumed as a primary energy source in the European context, and less than 0.4% of the European industry consumption of lubricant oil, results show that new bearing types and oil-free turbines (e.g., self-lubricating or water-lubricated turbines) can improve the sustainability of the hydropower sector, minimizing the risks and impacts associated with incidental oil spills and leakages. The provided data can also be used for Life Cycle Assessment analyses. Full article

Utilization of unharnessed hydro-power necessitates designing fish-friendly hydraulic machinery. Towards this effort, the present work investigates various methods for tracking fish motion, ranging from particle tracking methods to accurate, but computationally expensive, body tracking methods, such as immersed boundaries and overset meshes. Moreover, a novel uncoupled 6-Degree of Freedom tracking technique is proposed, based on an approximated pressure field around the tracked body of interest, using steady-state flow field data, and including collision detection to walls. The proposed method shows promising results in terms of accuracy, being comparable to the more computationally expensive fully coupled methods at a tiny fraction of the execution time. The new method reveals location of fish–blade impact, as well as statistics of forces, pressure and flow shear that a passing fish is subjected to, both in the normal and reverse operation of the turbine. The low computational cost of the proposed method renders it attractive for optimization studies. Full article

Taking into account both market benefits and power grid demand is one of the main challenges for cascade hydropower stations trading on electricity markets and secluding operation plan. This study develops a multi-objective optimal operation model for the long-term operation of cascade hydropower in different markets. Two objectives were formulated for economics benefits and carryover energy storage. One was to maximize the market utility value based on portfolio theory, for which conditional value at risk (CVaR) was applied to measure the risk of multi-markets. Another was the maximization of energy storage at the end of a year. The model was solved efficiently through a multi-objective particle swarm optimization (MOPSO). Under the framework of the MOPSO, the chaotic mutation search mechanism and elite individual retention mechanism were introduced to diversify and accelerate the non-inferior solution sets. Lastly, a dynamic updating of archives was established to collect the non-inferior solution. The proposed model was implemented on the hydropower plants on the Lancang River, which traded on the Yunnan Electricity Market (YEM). The results demonstrated non-inferior solution sets in wet, normal and dry years. A comparison in solution sets revealed an imbalanced mutual restriction between objectives, such that a 2.65 billion CNY increase in market utility costs a 13.96 billion kWh decrease in energy storage. In addition, the non-inferior solution provided various schemes for actual demands based on other evaluating indexes such as the minimum output, power generation and spillage. Full article

Tidal power generation technology has advanced quickly in recent years. In this study, the Hilbert-Huang transform (HHT) was used to examine the electrical energy distribution law of tidal power generation according to the time periods of days, months, and years based on observed data for tidal power generation. Our analysis summarized the tidal power generation law as follows: in the span of one day, the motor ran for 14 h before shutting off for 10 h. The frequency was 28 Hz, and the maximum voltage was 259 V. The tidal power generation swung twice a month, reaching its peak in the middle of the month and its trough at the beginning. The tidal power output fluctuated twice a year, reaching its peak in August, September, and October and its trough in February, March, and April. In the investigation of tidal power generation patterns, the HHT transformation’s precision and potency were confirmed. Full article

In order to ensure stable grid operatiFon and improve power quality, active or passive load rejection of pumped storage power stations (PSPS) inevitably occurs from time to time. The rapid closing of the guide vanes will cause drastic changes in pressure pulsations in the flow channel of the pump-turbine (PT) unit. The high-level pressure pulsations during load rejection transfer to the entire flow passage of the PT unit and generate strong vibrations on the head-cover and the connecting bolts. In this study, the 1D/3D joint simulation of the pipeline in a pumped storage power station and the turbine flow channels including the flow domains of the runner, crown chamber, band chamber, upper and lower labyrinths and pressure balance tubes is carried out first. Then, by applying the calculated pressure loads on the head-cover, stay vanes and bottom ring of the PT unit, the flow-induced dynamic behavior of the structures including the head-cover bolts is analyzed in detail. The results demonstrate that pressure loads on head-cover bolts change dramatically during the load rejection process. The flow-induced deformation of the inner head-cover during the load rejection is larger than that of other structures, and the flow-induced displacement and stress of different head-cover bolts are not uniform. The achieved conclusions in this study can be a useful reference for the design and operation of head-cover bolts for other PT units and high-head Francis turbine units. Full article

Pumped storage-power plants play an extremely important role in the modern smart grid due to their irreplaceable advantages in load peak-valley regulation, frequency modulation, and phase modulation. The number of start-stops per day of pump-turbine units is therefore also increasing. During the start-up transient process in turbine mode, the complex flow in runner passage, crown and band chambers, and seal labyrinth is able to induce severe vibration of non-rotating structures such as head cover, stay-ring, and pose a threat to the safe operation of the pump-turbine unit. In this article, the flow-induced vibration of the structures of a pump-turbine unit during its start-up process in turbine mode is studied. In the first place, this investigation establishes a three-dimensional model of the full flow passage and carries out a full three-dimensional CFD calculation based on one-dimensional pipeline calculation results for the start-up transient process. In the next place, by applying the fluid–structure interaction calculation method, the finite element analysis of non-rotating components of the pump-turbine unit is carried out. The flow-induced stresses and deformations of head cover, stay-ring, etc., are obtained and analyzed. The results reveal that the maximum deformation of the non-rotating structures is located at the inner edge of the head cover while the maximum stress appears at the trailing edge fillet of a stay vane. In summary, the dynamic stress of the non-rotating structures changes largely during the start-up process. The stress is strongly related to the axial thrust caused by the fluid flow. The achieved results can provide guidance for further fatigue life assessment of non-rotating structures and contribute to the structural safety design of pump-turbine units. Full article

Parameter identification is an important method to establish the governing system of a pumped storage unit. Appropriate parameters will make the governing system obtain better control performance. Therefore, in this study, an improved artificial hummingbird algorithm (IAHA) is proposed for the parameter identification of the governing system in a pumped storage unit. The algorithm integrates two key strategies to improve the optimization ability of the algorithm. First, the Chebyshev chaotic map is employed to initialize the artificial hummingbirds, which in turn increases and enhances the global search capability of the initial population. Second, the Levy flight is introduced in the guided foraging phase to expand the search space and avoid premature convergence. The performance of the proposed IAHA algorithm is compared with that of four other algorithms on 23 standard test functions, and the results show that IAHA has higher accuracy and faster convergence than the other four algorithms. Finally, IAHA was applied to the parameter identification of the governing system of a pumped storage unit to verify the effectiveness of the algorithm in tracking real-world problems. Full article

Stall flow patterns occur frequently in pump turbines under off-design operating conditions. These flow patterns may cause intensive pressure pulsations, sudden increases in the hydraulic forces of the runner, or other adverse consequences, and are some of the most notable subjects in the study of pump turbines. Existing methods for identifying stall flow patterns are not, however, sufficiently objective and accurate. In this study, a convolutional neural network (CNN) is built to identify and analyze stall flow patterns. The CNN consists of input, convolutional, downsampling, fully connected, and output layers. The runner flow field data from a model pump–turbine are simulated with three-dimensional computational fluid dynamics and part of the classifiable data are used to train and test the CNN. The testing results show that the CNN can predict whether or not a blade channel is stalled with an accuracy of 100%. Finally, the CNN is used to predict the flow status of the unclassifiable part of the simulated data, and the correlation between the flow status and the relative flow rate in the runner blade channel is analyzed and discussed. The results show that the CNN is more reliable in identifying stall flow patterns than using the existing methods. Full article

With the gradual opening of China’s electricity market, it is effective for cascade hydropower plants to simultaneously participate in both the monthly contract market and the day-ahead spot market to obtain higher power generation benefits. Hence, this paper studies the optimal decomposition model for the monthly contracted electricity of cascade hydropower plants considering the bidding space in the day-ahead spot market. The close hydraulic and electric connection between cascade hydropower plants, the implementation requirements of contracted electricity, and the uncertainty of the day-ahead market clearing price are all well considered. Several linearization techniques are proposed to address the nonlinear factors, including the objective function and the power generation function. A successive approximation (SA) approach, along with a mixed-integer linear programming (MILP) approach, is then developed to solve the proposed model. The presented model is verified by taking the decomposition of the monthly contracted electricity of cascade hydropower plants in China as an example. The results indicate that the developed model has high computational efficiency and can increase the power generation benefits compared with the conventional deterministic model. The effect of the penalty coefficient for imbalanced monthly contracted electricity is also evaluated, which provides a practical reference for market managers. Full article

Research on water flow in a pump inlet sump is presented. The main effort has been devoted to the study of the vortical structures’ appearance and their behavior. The study was conducted in a dedicated model of the pump sump consisting of a rectangular tank 1272 × 542 × 550 mm³ with a vertical bellmouth inlet 240 mm in diameter and a close-circuit water loop. Both Computational Fluid Dynamics (CFD) and experimental research methods have been applied. The advanced unsteady approach has been used for mathematical modeling to capture the flow-field dynamics. For experiments, the time-resolved Particle Image Velocimetry (PIV) method has been utilized. The mathematical modeling has been validated against the obtained experimental data; the main vortex core circulation is captured within 3%, while the overall flow topology is validated qualitatively. Three types of vortical structures have been detected: surface vortices, wall-attached vortices and bottom vortex. The most intense and stable is the bottom vortex; the surface and wall-attached vortices are found to be of random nature, both in their appearance and topology; they appear intermittently in time with various topologies. The dominant bottom vortex is relatively steady with weak, low-frequency dynamics; typical frequencies are up to 1 Hz. The origin of the vorticity of all large vortical structures is identified in the pump propeller rotation. Full article

The role of hydropower has become increasingly essential following the introduction of intermittent renewable energies. Quickly regulating power is needed, and the transient operations of hydropower plants have consequently become more frequent. Large pressure fluctuations occur during transient operations, leading to the premature fatigue and wear of hydraulic turbines. Investigations of the transient flow phenomena developed in small-scale turbine models are useful and accessible but limited. On the other hand, experimental and numerical studies of full-scale large turbines are challenging due to production losses, large scales, high Reynolds numbers, and computational demands. In the present work, the operation of a 10 MW Kaplan prototype turbine was modelled for two operating points on a propeller curve corresponding to the best efficiency point and part-load conditions. First, an analysis of the possible means of reducing the model complexity is presented. The influence of the boundary conditions, runner blade clearance, blade geometry and mesh size on the numerical results is discussed. Secondly, the results of the numerical simulations are presented and compared to experimental measurements performed on the prototype in order to validate the numerical model. The mean torque and pressure values were reasonably predicted at both operating points with the simplified model. An analysis of the pressure fluctuations at part load demonstrated that the numerical simulation captured the rotating vortex rope developed in the draft tube. The frequencies of the rotating and plunging components of the rotating vortex were accurately captured, but the amplitudes were underestimated compared to the experimental data. Full article

During the load rejection transient process of the prototype pump turbine units, the pressure fluctuations of the entire flow passage change drastically due to the rapid closing of guide vanes. The extremely unsteady pressure distribution in the flow domains including the crown chamber and the band chamber may cause a strong vibration on the stationary structures of the unit and result in large dynamic stress on the head cover, stay ring and bottom ring. In this paper, the numerical fluid dynamic analysis of the entire flow passage of a reversible prototype pump turbine during load rejection was performed. The flow characteristics in the runner passage, crown chamber, band chamber, seal labyrinths and balance tubes are analysed. The corresponding unsteady flow-induced dynamic behaviour of the head cover, stay vanes and bottom ring was investigated in detail. The analysed results show that the total deformation of the inner edge of the head cover closed to the main shaft is larger than that of other stationary structures of the unit during the load rejection. The maximum stress of the stay ring is larger than that of the head cover and the bottom ring and the maximum equivalent stress is located at the fillet of the stay vane trailing edge. The fluid–structure coupling calculation method and the analysed results can provide guidance for the design of stationary components of hydraulic machinery such as pump turbines, Francis turbines and centrifugal pumps with different heads. Full article

Small-scale hydropower installations make possible a transition towards decentralized electrical power production with very low ecological footprint. However, the prediction of their power potential is difficult, because the incoming flow velocity and the inlet and outlet water heights are often outside of the control of the operator. This leads to a need for a method capable of calculating an installation’s power potential and efficiency rapidly, in order to cover for many possible load cases. In this article, the use of a previously-published theoretical framework is demonstrated with the case of a mid-scale hydropower device, a 26 m long water vortex power plant. It is shown that a simplified CFD simulation with a single output (the mass flow rate) is sufficient to obtain values for the two coefficients in the model. Once this is done, it becomes possible to evaluate the device’s real-life performance, benchmarking it against reference values anchored in physical principles. The method can be used to provide design guidance and rapidly compare different load cases, providing answers that are not easily obtained using intuition or even experiments. These results are obtained for a computing cost several orders of magnitude smaller than those associated with a full description of the flow using CFD methods. Full article