As a large number of water conservancy projects have been put into use in recent years, water conservancy departments have accumulated a large amount of information about reservoir scheduling regulations. This paper analyzed the existing reservoir scheduling regulations, and proposed a construction method of reservoir scheduling regulations knowledge graph based on DataG. In the design of the ontology model, the top-down method of disassembling the ontology twice was adopted on the reservoir scheduling mode. The differentiated knowledge extraction was performed on the structured and unstructured data. In the knowledge reasoning, the reasoning path of preconditions, scheduling measures and scheduling objectives were analyzed and defined. Finally, the visualization of the reservoir scheduling regulation knowledge graph was introduced for the Three Gorges Reservoir. The knowledge graph of reservoir scheduling regulation meets the needs of spatiotemporal dimension, solves the problem of multi-source heterogeneous data extraction, and realizes intelligent retrieval and recommendation in the field of reservoir operation.

The performance of thrust bearing is very important to the energy conversion efficiency and stable operation of hydro-generator unit. Therefore, the thrust bearing of a hydropower station was taken as the research object. The characteristics of thrust bearing oil film under different rotating speed conditions were studied. The pressure, speed and temperature distribution inside the oil film were analyzed. The influence law of rotating speed on the performance of thrust bearing was clarified. The results show that the rotational speed cannot change the pressure distribution on the thrust pad surface, but with the increase of rotational speed, the relationship between the maximum pressure and rotational speed is almost linear; The high temperature zone on the thrust pad surface moves away from the main shaft towards the oil outlet side with the increase of the rotating speed, and the average temperature difference and the maximum temperature difference show an upward trend. At runaway speed, the thrust bearing needs to bear much higher pressure than the rated speed, and also needs to bear local high temperature. The maximum temperature difference at runaway speed is more than 40 K, which is easy to cause bearing bush burning. The research results provide theoretical support for the operation and optimal design of thrust bearings in hydropower stations.

In order to study the degradation of mica-quartz schist under the action of dry-wet cycles, which widely distributed in Shiyan, Hubei province was taken as the research object. The hydroscopicity test, wave velocity test and scanning electron microscope test were carried out on the samples under the action of dry-wet cycles, respectively, to reveal the law and mechanism of physical deterioration. The test results show that the water absorption increases greatly, the wave velocity decreases and gradually tends to be stable with the increase of the number of dry-wet cycles. Besides, the surface of the sample was gradually disseminated into reddish-brown, and the foliation was gradually cracked and connected. Finally, the flake particles became more, round and granulated, the number of cracks increased and the micro-fractures gradually expanded, so the water absorption rate increased and wave speed decreased of mica-quartz schist under the action of dry-wet cycles.

This paper aims at the complex flow response relationship in the short-term joint operation of Jindong-Guandi cascade hydropower stations in Yalong River basin. In order to predict the inflow response process of the Guandi hydropower station, the random forest (RF) model and support vector regression (SVR) model were combined to mine the nonlinear relationship, and compared with the traditional lag-time model and the Muskingum model. On this basis, two simulation dispatching models were established to test the applicability of each model in the short-term operation of cascade hydropower stations. The result shows that the RF-SVR model has a higher fitting ability for the flow response relationship between hydropower stations, which can reduce the errors in the formulation of short-term dispatching plan, and effectively reduce the deviation of daily generation and the risk of water level violation. The research results can provide a reference for making short-term dispatching schemes of cascade power stations under complex hydraulic connections.

Ganjiang river trail channel is affected by both upstream water and the backwater effect of Poyang Lake during the flood season. The study of the water level changes has guiding significance for river flood control and shipping. Based on the measured data from 1990 to 2019 at the hydrological station in the Ganjiang river trail channel, this paper adopted the Mann-Kendall trend test and the Pettitt test to analyze the trend of the characteristic water level during the flood season (flood season and backwater of Poyang Lake season). The results show that the water level of the Ganjiang river trail channel had a significant downward trend. The interannual variation of the water level during the flood season was relatively uniform, while it showed a fluctuating shape during the backwater of Poyang Lake season. The mutation years were all around 2002. The main reason for the decline of the water level during the flood period is the erosion of the riverbed. The downward trend of the riverbed has slowed down significantly after 2013, so water level during the flood period stabilized after 2016. The water level during the backwater of Poyang Lake season is mainly affected by the erosion of the riverbed, and the change of the downstream water level will also have a certain impact.

In order to study the surge wave characteristics of pumped storage power station with upstream and downstream surge chambers under small fluctuations, the mathematical model of small fluctuations in a pumped storage power station with this type of arrangement was derived based on the state-space method. The time-domain process of surge wave in the upstream and downstream surge chambers was solved by numerical simulation. The frequency-domain process of surge wave in the upstream and downstream surge chambers was obtained by the fast Fourier transform (FFT). Without considering the hydraulic coupling between the speed regulating system and the surge chamber system, the transfer function between the pressure pipeline flow and the water level of the surge chamber was established to obtain the amplitude-frequency characteristics of the surge chamber systems. The results show that the input signal frequency corresponding to the maximum amplitude of the surge wave in the upstream and downstream surge chambers is similar to the natural frequency of the surge chamber system, and the surge wave oscillation frequency in the surge chamber corresponds to the tail wave oscillation frequency of the unit speed. The surge wave characteristics of the surge chamber are closely related to the area of the surge chamber and the head loss coefficient of the water delivery tunnel. Increasing the area of two surge chambers can reduce the frequency and amplitude of surge wave in the upstream and downstream surge chambers, and enhance the stability of the system. The variation of head loss coefficient of the tunnel has no impact on the oscillation frequency of surge wave in the upstream and downstream surge chambers, but has a great impact on surge wave amplitude in the upstream and downstream surge chambers. The larger the head loss coefficient is, the smaller surge amplitude is, the system stability is better.

Pump device is the core of pump station, it is very important to carry out optimization research of pump unit. Taking the uniformity of axial velocity and the weighted average angle of velocity as optimization objectives, the hydraulic performance of inlet and outlet channels of a large vertical axial flow pump under pump mode and reverse power generation mode was optimized under all working conditions. Through the multi-scheme modeling of the inlet and outlet flow channels of the vertical axial flow pump device, the size of each section and the outer inverted line of the elbow section of the inlet and outlet flow channels were changed without changing the initial surface and the shape of the outlet section. The numerical simulation results of different inlet and outlet flow channels were compared. The distribution uniformity of flow velocity at inlet and outlet section of impeller, the average angle of weighted velocity, the hydraulic loss at inlet and outlet channel, and the variation rule of external characteristics and performance of axial flow pump device were analyzed in detail under pump mode and reverse power generation mode. The research results show that the hydraulic design of the flow channel under pump condition and reverse power generation condition can be considered comprehensively to improve the hydraulic performance of the pump unit under various operating modes in the design stage of the pump device for pump station. The research results provide theoretical support and engineering practice reference for hydraulic design and optimization of pump device in pump station.

Affected by the construction progress and other objective factors, the rock anchor beam may undergo loading with incomplete support, which seriously threatens the structural stability. In this paper, the rock anchored beam of a large hydropower station was taken as the research object. The three-dimensional nonlinear finite element simulation method was used to simulate the excavation of the main powerhouse and the filling of the rock anchored beam according to the actual excavation sequence. The continuous medium cementation element was introduced to simulate the weak contact between the beam concrete and the rock mass wall seat. The simulation results show that the load condition has a little impact on the stress and deformation of surrounding rocks, the initial support structure, and the rock anchor beam. The cementation surface between the surrounding rock and the rock anchor beam has a tendency to open, but it does not behavior obvious opening. The monitoring data such as the stress of the rock anchor beam and the deformation of the joint between the anchor beam and the rock wall remain basically unchanged, and no abnormal data are found, proving that the working state of the anchor beam is normal.

With the development of deep learning and image recognition technology, monitoring the water level of urban rivers and lakes through video has become a hot research topic in recent years. In order to realize the comprehensiveness of urban river and lake water level monitoring, a method of river and lake water level identification based on Mask RCNN was proposed. The water level was obtained by the water level characters and their position relations in the video images, and it was verified by the monitoring video of the real water level station in Dongying City, Shandong Province. The results show that the probability that the comparison error between the water level identification result and the measured data was less than 2 cm was 68.5%, the probability of error less than 3 cm is 76.9%, the probability of error less than 5 cm is 93.5%, the average error is 2.1 cm, and the root mean square error (RMSE) is 3.0 cm, which meets the recognition accuracy requirements of video water gauge level in Technical Outline of Digital Twin Watershed Construction (Trial). Therefore, the model has a good recognition effect and a certain application prospect.

In order to study the influence of loading rate on the damage evolution of hydraulic concrete, notched cubic specimens with side lengths of 300 mm and 450 mm were tested by wedge splitting test with different loading rates of 0.1 mm/s, 0.01 mm/s, 0.001 mm/s. Acoustic emission technology was used to monitor the acoustic emission signals of concrete in the damage process. Test results show that the variation of AE event rate during failure process of concrete can be divided into quiet, active, and attenuation period, among these the active period increases with the decrease of loading rate. The damage was defined according to the AE events, and it is found that the damage process of hydraulic concrete can be divided into three stages: crack initiation, acceleration and failure. The smaller the loading rate is, the faster the growth rate of the acceleration stage is. The damage evolution model based on the AE event obeys Weibull distribution, which can better reflect the influence of loading rates on the damage evolution of hydraulic concrete.