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Copyright of Water Conservancy Science & Techonlogy & Economy is the property of Water Conservancy Science & Technology & Economy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Different geographical locations have different time series and types of earthquake early warning data of hydropower stations, and the packet loss rate in data sharing is high. In this regard, a real-time sharing algorithm of earthquake early warning data of hydropower stations based on deep learning is proposed. The compressed sensing method is used to collect the seismic data of the hydropower station, and the dictionary learning algorithm based on ordered parallel atomic updating is introduced to improve the compressed sensing process and to sparse the seismic data of the hydropower station. Combining FCOS and DNN, the seismic velocity spectrum is picked up from the collected seismic data and used as the input of the convolutional neural network. The real-time sharing of earthquake early warning data is realized using the CDMA1x network and TCP data transmission protocol. Experiments show that the algorithm can accurately pick up the regional seismic velocity spectrum of hydropower stations, the packet loss rate of earthquake early warning data transmission is low, and the sharing results contain a variety of information, which can provide a variety of data for people who need information and has strong practicability. [ABSTRACT FROM AUTHOR]

Copyright of Geology & Resources is the property of Geology & Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hydropower stations are important infrastructures for generating clean energy. However, they are vulnerable to natural disasters such as earthquakes, which can cause severe damage and even lead to catastrophic failures. Therefore, it is essential to develop effective strategies for maximizing hydropower station safety against earthquakes. To evaluate the potential shear rate of surrounding rock layers, the shear wave velocity (Vs) parameter can be used as a useful tool. This parameter helps to determine the velocity at which shear waves travel through the rock layers, which can indicate their stability and susceptibility to earthquakes. This study will investigate the significance of the Vs parameter in evaluating the potential shear rate of rock layers surrounding hydropower stations and how it can be used to ensure their safety and efficiency in earthquake-prone regions. Furthermore, a novel approach is proposed in this research, which involves using extreme learning machine (ELM) technology to predict Vs and enhance the seismic safety of hydropower stations. The ELM model predicts the Vs of the soil layers around the hydropower station, a crucial factor in determining the structure's seismic response. The predicted Vs is then used to assess seismic hazard and design appropriate safety measures. The ML-ELM model outperformed both the ELM and empirical models, with an RMSE of 0.0432 μs/ft and R2 of 0.9954, as well as fewer outlier data predictions. This approach shows promise for predicting Vs in similar environments, and future research could explore its effectiveness in other datasets and practical applications. [ABSTRACT FROM AUTHOR]

The safe and steady operation of hydropower generation systems is crucial for electricity output in the grid. However, hydropower stations have complicated interior structures, making defect detection difficult without disassembly inspections. The application of digital modeling to hydropower stations will effectively promote the intelligent transformation of hydropower stations as well as reduce the maintenance costs of the system. This study provides a model of the power generating and transmission system for hydropower plants, with an emphasis on primary equipment and measured data. The model utilizes PSCAD to digitalize state response in hydropower plants with various short-circuit faults. The fault information is identified and learned using the Adaptive Time–Frequency Memory (AD-TFM) deep learning model. It is demonstrated that our proposed method can effectively obtain the fault information through radio frequency identification (RFID). The accuracy of the traditional method is 0.90, while the results for AD-TFM show a fault classification accuracy of 0.92, which is more than enough to identify multiple fault types compared to the existing methods. [ABSTRACT FROM AUTHOR]

Amid diverse water demands, the conflict between ecological flow adjustments and power generation flow adjustments in hydropower station water resource dispatching, coupled with an increasing diversity of constraints, complicates the issue of water resource optimization and dispatching. How to scientifically develop feedback regulation mechanisms to promote a virtuous ecological cycle, fine tune existing hydropower station scheduling plans, and achieve multi-objective optimization scheduling is the core issue in researching the comprehensive utilization of water resources. This study establishes a reservoir flow regulation model with the objective functions of maximizing power generation and achieving optimal average ecological protection. The model, constrained by water balance, reservoir capacity, unit output, and unit overflow, was optimized and solved using the genetic algorithm-backpropagation neural network (GA-BPNN) approach. This study establishes a reservoir flow regulation model with the GA-BPNN algorithm was applied in multi-objective optimization to identify an optimal solution that maximizes overall system performance while adhering to ecological flow constraints. The results indicate that the optimized plan has performed effectively in hydropower station operations. It not only satisfies ecological flow requirements, but also significantly enhances power generation efficiency. Specifically, power generation increased by 32,680 kw·h, a 23.85 % growth rate. The optimized plan significantly enhances the comprehensive utilization efficiency of water resources. It offers a scientific basis for the rational planning, dispatching and utilization of water resources in hydropower stations and reservoirs.

Abstract This paper studies the optimization of hydraulic parameters for pipeline system of hydropower station with super long headrace tunnel (HSSLHT) based on mayfly algorithm considering operational scenarios. Firstly, the state equation of HSSLHT under load disturbance is derived. The optimization design of hydraulic parameters for pipeline system based on mayfly algorithm is proposed. Then, the optimization of hydraulic parameters is conducted and analyzed. Finally, the effects of pipeline diameters and transfer coefficients of turbines on the optimization of hydraulic parameters for pipeline systems are revealed. The results show that the optimization of hydraulic parameters for pipeline system is a multiobjective problem, and the several objective functions exhibit significant conflicts. Compared to the firefly algorithm and genetic algorithm, the objective function under mayfly algorithm is improved by 14.7% and 5.1%, respectively. The mayfly algorithm can make the hydraulic parameters for the pipeline system reach the Pareto optimal solution under both load decrease condition and load increase condition. The diameter of penstock has an obvious influence on the robustness of dynamic performance of HSSLHT. When the diameter of penstock increases by 30%, the robustness of HSSLHT becomes worse and the robustness index deteriorates by 57%. The reason is that the flow inertia of penstock becomes smaller with the increase of diameter, and the flow inertia of penstock is favorable for resisting disturbance of HSSLHT. The coefficient of throttled orifice head loss and the lengths and head losses of headrace tunnel and penstock are the key hydraulic parameters for matching the operation of HSSLHT.

This paper studies the optimization of hydraulic parameters for pipeline system of hydropower station with super long headrace tunnel (HSSLHT) based on mayfly algorithm considering operational scenarios. Firstly, the state equation of HSSLHT under load disturbance is derived. The optimization design of hydraulic parameters for pipeline system based on mayfly algorithm is proposed. Then, the optimization of hydraulic parameters is conducted and analyzed. Finally, the effects of pipeline diameters and transfer coefficients of turbines on the optimization of hydraulic parameters for pipeline systems are revealed. The results show that the optimization of hydraulic parameters for pipeline system is a multiobjective problem, and the several objective functions exhibit significant conflicts. Compared to the firefly algorithm and genetic algorithm, the objective function under mayfly algorithm is improved by 14.7% and 5.1%, respectively. The mayfly algorithm can make the hydraulic parameters for the pipeline system reach the Pareto optimal solution under both load decrease condition and load increase condition. The diameter of penstock has an obvious influence on the robustness of dynamic performance of HSSLHT. When the diameter of penstock increases by 30%, the robustness of HSSLHT becomes worse and the robustness index deteriorates by 57%. The reason is that the flow inertia of penstock becomes smaller with the increase of diameter, and the flow inertia of penstock is favorable for resisting disturbance of HSSLHT. The coefficient of throttled orifice head loss and the lengths and head losses of headrace tunnel and penstock are the key hydraulic parameters for matching the operation of HSSLHT. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the shortcomings of the existing methods of energy efficiency management level evaluation for hydropower stations, this paper introduces Analytic Hierarchy Process (AHP) method and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method into the evaluation process. The evaluation index system of energy efficiency management of hydropower station is constructed by considering the three aspects of economy, safety and management comprehensively. In order to overcome the shortcomings of the nine scale method, the paper uses the exponential scale method to determine the weight of each index. What's more, TOPSIS method and expert scoring method are used to score the quantitative indicators and the qualitative indicators, respectively, so as to further realize the comprehensive evaluation of the hydropower station energy efficiency management level. An actual hydropower station is taken as an example to analyze and calculate the score of the energy efficiency management level of the hydropower station from 2018 to 2022.The results show that the energy efficiency management level of the hydropower station is on the rise. [ABSTRACT FROM AUTHOR]

Combined with the general layout of Yaojiaping Hydraulic Project, this paper carries out three dimensional finite element stress analysis and flow field calculation respectively for the diversion system of the main power station with symmetrical Y shape and asymmetric Y shape crescent ribbed steel bifurcation. The calculation results show that the stress distribution at the two sides of symmetrical bifurcation is relatively uniform and the size of the rib is smaller. However, the stress concentration is greater near point A on the inner surface of the main branch taper intersecting line In terms of hydraulics, the head loss of two branches of asymmetric bifurcated pipe is not equal. The straight branch pipe with the main coaxial line has the smallest head loss, and the inclined branch pipe has the largest head loss, but not more than 0.358m of symmetrical bifurcation. It shows that the asymmetric bifurcation is slightly better than the symmetrical Y-shaped bifurcation in terms of head loss and flow pattern of the bifurcation. Considering the structural and hydraulic characteristics of bifurcation as well as the engineering topography, it is suggested that the asymmetric Y-shaped bifurcation layout should be chosen for the diversion system of the main power station in Yaojiaping Hydropower Project. [ABSTRACT FROM AUTHOR]

Hydropower stations that are part of the grid system frequently encounter challenges related to the uneven distribution of power generation and associated benefits, primarily stemming from delays in obtaining timely load data. This research addresses this issue by developing a scheduling model that combines power load prediction and dual-objective optimization. The practical application of this model is demonstrated in a real-case scenario, focusing on the Shatuo Hydropower Station in China. In contrast to current models, the suggested model can achieve optimal dispatch for grid-connected hydropower stations even when power load data is unavailable. Initially, the model assesses various prediction models for estimating power load and subsequently incorporates the predictions into the GA-NSGA-II algorithm, specifically an enhanced elite non-dominated sorting genetic algorithm. This integration is performed while considering the proposed objective functions to optimize the discharge flow of the hydropower station. The outcomes reveal that the CNN-GRU model, denoting Convolutional Neural Network-Gated Recursive Unit, exhibits the highest prediction accuracy, achieving R-squared and RMSE (i.e., Root Mean Square Error) values of 0.991 and 0.026, respectively. The variance between scheduling based on predicted load values and actual load values is minimal, staying within 5 (m3/s), showcasing practical effectiveness. The optimized scheduling outcomes in the real case study yield dual advantages, meeting both the demands of ship navigation and hydropower generation, thus achieving a harmonious balance between the two requirements. This approach addresses the real-world challenges associated with delayed load data collection and insufficient scheduling, offering an efficient solution for managing hydropower station scheduling to meet both power generation and navigation needs.

In order to explore the application of fluid mechanics technology in water conservancy and hydropower stations, the author proposes the study of hydraulic engineering fluid mechanics model based on trigonometric function relationship equation. According to standard k- ε Double equation and Reynolds time average (N-S) equation, given the runner boundary conditions, establish the mathematical model of the internal flow of the hydraulic turbine. Through CFD simulation technology, the runner of hydraulic turbine is numerically simulated to obtain the velocity distribution and blade pressure distribution inside the runner, movable guide vane and fixed guide vane, the reliability of the design is improved, and the application of CFD technology in hydropower project is analyzed with an example. The results show that, when the diameter of guide vane distribution circle is 4760mm, the scheme is optimal, and the relative efficiency under the optimal working condition is 96.35%. The flow of the modified runner from the inlet of the volute to the outlet of the draft tube is very stable under the optimal working condition, and there is no obvious vortex, especially there is no obvious vortex belt and vortex at the outlet of the runner; There is no obvious vortex in the draft tube, the flow on both sides of the pier is very uniform, and the flow on one side is not significantly greater than that on the other side, which fully shows that the flow performance of the modified runner is good. After reconstruction, the runner outlet flow field is good, and the internal flow line of the draft tube is smooth. The application prospect of hydrodynamic algorithm for hydraulic engineering is relatively broad.

Glyptosternum maculatum, predominantly found in the middle and upper reaches of the Yarlung Zangbo River (YR) and its tributaries, is a fish species accorded second-class national protection. In 2021, it was recognized as one of the top ten excellent aquatic germplasm resources in China. However, its living conditions are far from promising. Therefore, in this study, we used the MaxEnt model to simulate potentially suitable habitat for G. maculatum, and then reconstructed the ecologically suitable habitat for G. maculatum using the kernel density algorithm after taking into account the distribution characteristics of hydropower stations. We predicted changes in area of the ecologically suitable habitat for G. maculatum under future climate change scenarios. The results indicate that the primary ecologically suitable areas for G. maculatum are situated in Ngamring County, Saga County, and Mainling County, covering a total area of 553.15 km2. Flow accumulation, NDVI, and the seasonality of temperature change are the main environmental factors affecting the distribution of G. maculatum. In the future, considering the ongoing impacts of factors such as hydropower stations and climate conditions, the projected suitable habitat area for G. maculatum is expected to span between 433.90 and 516.23 km2, marking a forecasted decrease of approximately 6.68 to 21.56 %. To prevent further reduction of suitable habitat, protective measures should be taken as early as possible.

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The impeller, regarded as the central component of a centrifugal pump, plays a pivotal role in dictating overall performance. Overcoming challenges arising from the complexity of design parameters and the time-intensive nature of the design process has been a persistent obstacle to widespread adoption. In this study, we integrated ANSYS-CFX 2023 software with innovative inverse design techniques to optimize the impeller design within a centrifugal pump system. Our investigation reveals groundbreaking insights, highlighting the significant influence of both blade load and shaft surface geometry on impeller performance. Notably, through load optimization, substantial enhancements in centrifugal pump efficiency were achieved, demonstrating improvements of 1.8% and 1.7% under flow conditions of 1.0 Q and 0.8 Q, respectively. Further, the efficiency gains of 0.44% and 0.36% were achieved in their corresponding flow conditions. The optimization of blade load and shaft surface configuration notably facilitated a more homogenized internal flow pattern within the impeller. These novel findings contribute substantively to the theoretical foundations underpinning centrifugal pump impeller design, offering engineers a valuable reference to elevate their performance. Our utilization of ANSYS-CFX software in conjunction with inverse design methodologies showcases a promising avenue for advancing impeller design, ultimately culminating in superior efficiency and performance for centrifugal pumps. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a control and regulating project, the hydropower station in the Yigongzangbu basin of Tibet plays a vital role in meeting the electricity demand of the Tibetan power grid. Identifying this hydropower station’s present-day in-situ stress environment and understanding the characteristics of in-situ stress distribution at critical locations such as underground plants and diversion tunnels are essential to ensure its engineering safety. Based on the tectonic and geological background and rock conditions of the project area, we carried out hydraulic fracturing in-situ stress measurements by placing boreholes and obtained in-situ stress data from 4 measurement points (8 boreholes). A finite element three-dimensional geological model was established according to the existing geological conditions. The measured stress state revealed the loading conditions, and the inverse analysis of the stress field in the engineering area was made. The maximum horizontal principal stress ranges from 4.17 to 16.93 MPa in the 2D test and 14.2 to 16.23 MPa in the 3D test. The maximum horizontal principal stress orientation is NE 38°to NE 47°, and the NE direction dominates the present-day tectonic stress field. In the 2995-meter elevation horizontal plane of the underground plant area of the power station, the stress values of σ1, σ2, and σ3 range from 11.70 to 12.12 MPa, 9.81 to 10.74 MPa, and 5.22 to 6.85 MPa, respectively. The maximum principal stress value of σ1, σ2, and σ3 along the diversion tunnel range from 11.8 to 14.05 MPa, 10.13 to 12.83 MPa, and 4.56 to 8.49 MPa, respectively. The axis direction of this hydropower station’s underground plant and the diversion tunnel’s axis direction intersect at a slight angle with the direction of the measured maximum principal stress, and the ground stress field is favorable to the stability of the project cavern. It is necessary to consider the actual geological conditions and adopt suitable tunnel construction technology in the later construction process. The construction monitoring should also be strengthened to ensure the project’s safe construction.

In this study, full-scale fire experiments were conducted in a hydropower station to investigate smoke propagation during tunnel construction. The flame height, smoke temperature and stratification, smoke descent and spread velocity were analyzed via measurements and on-site observations. The initial combustion stage was largely affected by ignition source during tunnel construction for diesel pool fire, and the average flame height in the fully developed stage could reach 1.4–2.1 m in experimental fire scenarios. The gradient of the smoke temperature evolution near the fire was the opposite for the upstream and downstream regions. The longitudinal temperature distribution was concentrated in a small range at the heights of the smoke layer, and gradually decreased by air entrainment as the height decreased, while further increasing in the lower half of the tunnel height in the near-fire region under heat radiation from the fire source. Moreover, distinct and stable smoke stratification formed during the fully developed combustion stage, and the smoke layer interface was at approximately half the tunnel height. Smoke descent was aggravated in the decay stage of combustion, and the fire risk remained high after the fully developed period. The smoke front spread velocity was empirically determined for the full-scale tunnel fire scenarios. Conclusions from full-scale experiments can support smoke control design and on-site fire emergency response plans for hydropower stations.

Sanmenxia hydro-junction is the first sizable water conservation project constructed on the Yellow River’s main stream during the socialist revolution and construction period following the foundation of new China. Due to lacking understanding and experience with sediment-laden water rivers, after the project was constructed in 1960, it was reconstructed and/or modified twice. This paper presents the case study of the Sanmenxia project. [ABSTRACT FROM AUTHOR]

Hydropower station is vital for the stable growth of the national economy. How to timely warn the possible faults of hydropower stations has become an increasingly popular research topic. The traditional detection model is difficult to detect the small abnormal changes in the data, and these abnormal changes are often the precursor of faults. To improve the sensitivity of the traditional detection model, this study introduced a weight factor into the traditional LSTM detection model. By using the correction mechanism, the LSTM correction model makes the prediction model never deviate from the normal track following the appearance of abnormal data. This ensures that the model can generate large residuals after abnormal data occur so that we can detect these abnormal data in time. Finally, this paper puts forward two factors related to equipment health and integrates these two factors to form a health index. The results show that the LSTM correction model based on the health index can not only detect small changes that cannot be detected by traditional detection models but also knows the wear and tear of equipment during operation based on the changes in health indicators. [ABSTRACT FROM AUTHOR]

The underground air intake tunnel is a natural source of heat and cold that can be utilised to significantly condition the air entering the underground plant, thereby reducing the energy consumption of the plant. The heat and humidity environments of three underground tunnels were tested in winter and summer. The tunnels belong to Jiangxi Hongping Hydropower Station, which has significant cooling and heating characteristics in the air intake tunnel, Sichuan Xiluodu Hydropower Station, the world’s largest underground power station, and Hainan Qiongzhong Hydropower Station, the southernmost in China. The heat and humidity exchange pattern between the underground air intake tunnel of the power station and the air was analysed, including temperature and humidity trends, condensation zoning, inter-seasonal thermoregulation effect. Furthermore, the cooling and heating capacity of the air intake tunnel was calculated and analysed. The results show that: the greater the length and cross-sectional area of the tunnel, the greater the cooling and heating quantity; there is a noticeable difference in heat transfer capacity between different air intake tunnels, and the tunnel length is not a decisive factor for the heat transfer capacity, the heat transfer capacity (enthalpy difference) per unit mass flow rate of air in the air intake tunnels of Jiangxi (1500 m) is more than twice that of Sichuan (2800 m); the test cooling capacity of the Hainan (1400 m) tunnel reaches 606 kW (while the plant chiller rated cooling capacity of 2082 kW), the air intake tunnel can be used as an underground plant energy-efficient air conditioning, the equipment selection of plant mechanical air conditioning should take into account the air handling capacity of the air intake tunnel.

The cofferdam is a temporary water retaining structure built to protect the foundation pit in the construction of hydraulic engineering. Its layout has great influence to the flood safety, project progress and cost. Relying on the diversion tunnel project of a hydropower station, this paper firstly optimized the design of the cofferdam type at the outlet of the diversion tunnel, and then compares various construction schemes such as earth rock cofferdams, concrete cofferdams, stoplogs gate, and concrete cutoff walls. The cofferdam scheme was designed, and the construction technology and construction scheme of the cofferdam were systematically expounded. The analysis results show that the cofferdam at the exit of the diversion tunnel uses the stoplogs gate type to control the flood season, which meets the requirements of the project safety flood control, significantly reduces the amount of cofferdam engineering and the project cost, and has strong technical feasibility. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Geomechanics is the property of Journal of Geomechanics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rock coring of the reservoir in the Bohai A field is difficult. The cores of the target section in the study area are loose, making it difficult to accurately measure the core-bound water saturation. The purpose of this research was to develop and validate a method for calculating a reservoir core-bound water saturation ratio using the cast thin section. First, pepper noise denoising and image enhancement were performed on the thin section by median filtering and gamma variation. Based on this, the enhanced sheet images were thresholded for segmentation by the two-dimensional OTSU algorithm, which automatically picked up the thin section pore-specific parameters. Then, the thin section image was equivalent to a capillary cross-section, while the thin film water fused to the pore surface was observed as bound water. For hydrophilic rocks with a strong homogeneity, the area of thin film water in the pore space of the sheet was divided by the total area of the pore space, which produced the bound water saturation. Next, the theoretical relationship between the film water thickness and the critical pore throat radius was derived based on the Young–Laplace equation. The bound water saturation of the rock was calculated by combining the pore perimeter and the area that was automatically picked up from the thin film for a given critical pore throat radius of the rock. Finally, 22 images of thin sections of sparse sandstone from the coring well section of the study area were image processed using the new method proposed in this paper, and the bound water saturation was calculated. The calculated results were compared with 22 NMR-bound water saturations and 11 semi-permeable baffle plate-bound water saturations in the same layer section. The results showed that the bound water saturation values calculated by the three methods produced consistent trends with absolute errors within 5%. The calculated results confirm the reliability of the method proposed in this paper. This method can effectively avoid the problem of the inaccurate results of core experiments due to the easy damage of sparse sandstone and provides a new idea for the accurate determination of the bound water saturation of sparse sandstone. [ABSTRACT FROM AUTHOR]

Copyright of China Rural Water & Hydropower is the property of China Rural Water & Hydropower Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Water Conservancy Science & Techonlogy & Economy is the property of Water Conservancy Science & Technology & Economy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The hydropower station real-time safety monitoring is not only related to the safety, but also to the generation benefit of the power station. However, as the amount of monitoring data is very huge, and the dam structure is very complex, real-time monitoring cannot be carried out in most of the dam. It is useful to develop a high-performance safety monitoring system to assist the dam safety management work. As such, the paper introduces an expert system for dam safety management with a mode which can carry out the entire process of real-time dam safety monitoring, covering abnormal importing data, abnormal data changes, monitoring work, dam safety. The system has abundant functions such as dam safety analysis, visual query and remote consultation, etc. The system has been successfully applied to more than ten dam projects in China. The application shows that reliable data evaluation can identify data anomalies such as single point jump, multi point outlier and step change. Trend tracking can find possible structural changes. And clustering comprehensive evaluation can give a reasonable evaluation of the safety state of different parts of the dam. Complete online system can provide a supporting decision-making platform for the safety monitoring of the dams and improve the efficiency of power station management.

In order to investigate the hydraulic characteristics and optimal operation schemes of the intake of hydropower stations, a 3D numerical model was built to study the velocity distribution, head loss and other hydraulic behaviors. The results show that with the increase of the layer numberof the stop log gates, the flow space at the top of the stop log gates is continuously compressed, which intensifies the turbulence of the water inlet, leading to the occurrence of vortex at the inlet. The growth of the head loss increases sharply in the early stage and then slows down with the increase of the layer number of the stop log gates. Combined with vertical water temperature distribution in the reservoir area, in the season when the vertical temperature difference is small, a lower layer number of the stop log gates is recommended to reduce head loss, while in the season with large vertical temperature difference, the layer number of the stop log gates can be reasonably selected according to requirements to meet the performance objectives for temperature. These results provide a reference and guide for engineering design of stratified water intake. [ABSTRACT FROM AUTHOR]

The energy-conversion stability of hydropower is critical to satisfy the growing demand for electricity. In low-head hydropower plants, a gravitational surface vortex is easily generated, which causes irregular shock vibrations that damage turbine performance and input-flow stability. The gravitational surface vortex is a complex fluid dynamic problem with high nonlinear features. Here, we thoroughly investigate its essential hydrodynamic properties, such as Ekman layer transport, heat/mass transfer, pressure pulsation, and vortex-induced vibration, and we note some significant scientific issues as well as future research directions and opportunities. Our findings show that the turbulent Ekman layer analytical solution and vortex multi-scale modeling technology, the working condition of the vortex across the scale heat/mass transfer mechanism, the high-precision measurement technology for high-speed turbulent vortexes, and the gas–liquid–solid three-phase vortex dynamics model are the main research directions. The vortex-induced vibration transition mechanism of particle flow in complex restricted pipelines, as well as the improvement of signal processing algorithms and a better design of anti-spin/vortex elimination devices, continue to draw attention. The relevant result can offer a helpful reference for fluid-induced vibration detection and provide a technical solution for hydropower energy conversion. [ABSTRACT FROM AUTHOR]

Water-level fluctuation is a crucially important hydraulic factor to meet the safety of ship navigation. Due to the uncertainty and evolution of the maximum amplitude of water-level variation in the approach channel, the river reach between two dams located along the Yangtze River in China is selected as a study area and the impact of various operating conditions of the cascade hydro-plant on the maximum amplitude of water-level variation at typical sites is revealed combining the orthogonal test method and a hydrodynamic model. In addition, the critical threshold for the water-level variation at the lower lock head of the ship lift is explored using maximum entropy method. Results demonstrate that flow variation and regulation time are the most prominent factors affecting water-level fluctuation at the lower lock head of the ship lift, and the existing standard (0.5 m within 1 h and 0.3 m within 30 min) for controlling the maximum variation in water level at the lower lock head of the ship lift is reasonable and more safety oriented. This study provides a novel perspective to understand the response of water-level fluctuation to the stochasticity of operating conditions for the cascade hydropower stations. HIGHLIGHTS A one-dimensional hydrodynamic model was developed for validating the water-level fluctuation in the approach channel based on a physics model test.; Using orthogonal array design method to address the intricate scenarios from the dual cascade hydropower stations.; Using maximum entropy method (MEM) to examine the maximum water-level variation under the operation of large-scale cascade hydropower stations.;

Hydroelectricity is a major source of renewable electricity originating from a turbine driven by dammed large-volume water via a penstock or a drop shaft. Shafts suffer from risks of collapse due to the pressure from exterior structures and the erosion from inner water flow. Vertical shafts are an important part of hydroelectric power generation systems, and detecting defects in shafts guarantees the stable operation of hydropower stations. However, shaft defect detection is a great challenge due to the poor conditions, large drop in height, limited entrance size, lack of light, and damp air, where suitable technology and equipment are not available. Aiming at defect detection for vertical shafts, we have developed a defect-detecting system based on unmanned airships, integrated panoramic CCD cameras, three-dimensional laser scanners, inertial measurement units, barometric altimeters, illumination sensors, and control modules. Shaft defect detection methods are proposed by fusing the multimodal image features to extract typical defects on concrete surfaces. Compared with machine learning methods, the proposed method achieves the highest overall accuracy of 90.90% for defect detection. Our system was validated by experiments in the shafts of the Nuozhadu hydropower station to be functional for defect detection, which demonstrates its capability of reducing the risk of collapse and improving safety.

This paper investigates the synergetic control strategy for water hammer wave and mass wave in hydropower station with downstream channel. Firstly, the mathematical model of hydropower station with downstream channel (HSDC) and hydropower station with downstream channel and surge tank (HSDCST) are established. Then, the controller formula of HSDC and HSDCST are derived using the synergetic theory. Furthermore, it is parsed that the dynamic characteristics of HSDC and HSDCST to various disturbances under synergetic control strategy. Finally, the robustness and applicability of synergetic control strategy for HSDC and HSDCST are analyzed. The results indicate that the hydropower station under the synergetic control strategy has excellent dynamic characteristics with employing sensitive response, small overshoot, fast attenuation speed and no static error. The synergetic control strategy is superior to the PID control strategy under various disturbances in controlling the amplitude of water hammer wave in HSDC, which is down 12.5%. The attenuation of mass wave in HSDCST under synergetic control strategy is faster, and the settling time is 6.16s less than that of PID control strategy. Compared with PID control strategy, it is the robustness of synergetic control strategy that are much more advantageous for HSDC and HSDCST. Specifically, RI value is about 1.65, 0.18 for HSDC and 2.21, 0.25 for HSDCST under synergetic control strategy, while it is about 3.05, 1.20 and 3.32, 1.30 under PID control strategy. Moreover, the synergetic control strategy has a wide applicability in controlling the water hammer wave in HSDC and mass wave in HSDCST.

In order to explore the spatial layout of fish assemblages and their related environmental factors, a survey of species composition was conducted in the Anning River. From 2018 to 2021, 28 sites at 987–2,077 m in altitude were surveyed, gathering 64 species in total, of which 60 were native and 4 were exotic. Fifteen of the species sampled were indigenous to the upper Yangtze River, and two were classified as critically endangered or endangered. Fish communities displayed significant upstream-to-downstream variation. There are two site-groups, one covering upstream and tributaries and the other covering midstream and downstream. The upstream-tributary fish assemblages had a dominance of Nemacheilidae and Schizothoracinae, which are plateau species with habitat preferences for boulders and fast-flowing water. Conversely, the mid-downstream fish assemblages had a dominance of Gobioninae, Cyprininae, Bagridae and Siluridae, which are common river species that prefer slow-flowing water. The spatial patterns of these fish communities were chiefly affected by altitude and substratum composition. The fish assemblage pattern was consistent with the zonation concept because the fish communities changed abruptly and clearly along the upstream–downstream axis. The findings of this study offer a crucial research foundation for comprehending the fish assemblages of mountainous rivers, which will be conducive to biodiversity management and habitat preservation of aquatic species.

This paper aims to study the nonlinear hydraulic coupling characteristics and energy conversion mechanism of pipeline - surge tank system of hydropower station with super long headrace tunnel. Firstly, the model of hydropower station considering nonlinear hydraulic coupling of pipeline - surge tank system is established. Then, the dynamic behaviors are evaluated, and the effects of nonlinear head losses of pipeline - surge tank system on dynamic behaviors are analyzed. Finally, the energy conversion mechanism of pipeline - surge tank system is revealed. The results indicate that both the nonlinear head loss term of super long headrace tunnel and linear head loss term of penstock are unfavorable for stability. The nonlinear throttling orifice head loss of surge tank has a remarkable impact on dynamic response processes. The nonlinear head losses of pipeline - surge tank system mainly affect the kinetic energy of flow in pipeline. A part of the kinetic energy of flow in pipeline interconverts with the kinetic energy of flow in surge tank. [ABSTRACT FROM AUTHOR]

International investors in large infrastructure projects face numerous risks. To explore this issue, this paper compares the development of two hydropower stations in Rasuwa District, Nepal: Upper Trishuli 3A, which is fully funded by a Chinese government bank, and Rasuwagadhi, which is fully funded by local government banks. The construction of these two plants was compared between 2012 and 2020 using a visual interpretation method to extract data on roads, buildings, dams, and vehicles from 1-m-resolution remote sensing imagery. Two methods were used to compare the environmental impacts of each plant. Landsat 7/8 30-m imagery was used to monitor changes in the normalized difference vegetation index around the Upper Trishuli 3A hydropower station from 2012 to 2020 and around the Rasuwagadhi hydropower station from 2014 to 2020. Then, 1-m-resolution imagery was used to observe land-cover differences in these areas and time periods. The results indicate that: (1) despite various challenges, such as geological disasters, the COVID-19 pandemic, and a blockade by the Indian government, there was no difference in construction progress between the two hydropower stations. (2) The Upper Trishuli 3A Hydropower Station was associated with better environmental protection work, as there were continuous declines in vegetation growth near Rasuwagadhi and increased overall vegetation growth near Upper Trishuli 3A. (3) Energy projects funded by the Belt and Road Initiative have benefited developing countries enormously. Finally, local conditions should be thoroughly investigated during the construction of foreign-funded power stations. [ABSTRACT FROM AUTHOR]

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This paper studies the critical sectional area of surge tank (SAST) based on bifurcation and chaos behaviors of hydraulic-mechanical coupling hydropower station (HMCHS). Firstly, the model of HMCHS is established. Then, the criterion for the critical stable state (CSS) based on bifurcation behavior is derived. The critical SAST based on bifurcation behavior is determined and analyzed. Finally, the occurrence of chaos motion is identified. By analyzing the effect of SAST on chaos behavior, the critical SAST based on chaos behavior is determined. The results indicate that the critical SAST based on bifurcation behavior corresponds to CSS of HMCHS. Among nonlinearity of head loss of headrace tunnel, throttling orifice head loss of surge tank and nonlinearity of turbine characteristics, the influence degree of the nonlinearity of head loss of headrace tunnel is the greatest. Under the coupling effect of those three factors, the critical SAST based on bifurcation behavior becomes greater under load decrease and becomes less under load increase. For the chaos motion caused by low- and high-frequency oscillations together, there is the concept of critical SAST based on chaos behavior. With the decrease in proportional gain of governor, the critical SAST based on chaos behavior becomes less. [ABSTRACT FROM AUTHOR]

Amid diverse water demands, the conflict between ecological flow adjustments and power generation flow adjustments in hydropower station water resource dispatching, coupled with an increasing diversity of constraints, complicates the issue of water resource optimization and dispatching. How to scientifically develop feedback regulation mechanisms to promote a virtuous ecological cycle, fine tune existing hydropower station scheduling plans, and achieve multi-objective optimization scheduling is the core issue in researching the comprehensive utilization of water resources. This study establishes a reservoir flow regulation model with the objective functions of maximizing power generation and achieving optimal average ecological protection. The model, constrained by water balance, reservoir capacity, unit output, and unit overflow, was optimized and solved using the genetic algorithm-backpropagation neural network (GA-BPNN) approach. This study establishes a reservoir flow regulation model with the GA-BPNN algorithm was applied in multi-objective optimization to identify an optimal solution that maximizes overall system performance while adhering to ecological flow constraints. The results indicate that the optimized plan has performed effectively in hydropower station operations. It not only satisfies ecological flow requirements, but also significantly enhances power generation efficiency. Specifically, power generation increased by 32,680 kw·h, a 23.85 % growth rate. The optimized plan significantly enhances the comprehensive utilization efficiency of water resources. It offers a scientific basis for the rational planning, dispatching and utilization of water resources in hydropower stations and reservoirs., Competing Interests: The authors declare the following financial interests/personal relationships which may be considered as potential competing interests.Yong Luo has patent pending to Yong Luo. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Author.)