The Shiliushubao landslide is one of the giant landslides with complex structure in the Three Gorges Reservoir area. Since the dam was filled with water, the landslide has shown signs of revival, causing loss of life and property to several people around. In order to study the deformation failure mode and response mechanism of Shiliushubao landslide under the fluctuation of reservoir water level, the large-scale physical model test was used to accurately control the fluctuation condition of the experimental reservoir water level, and the displacement sensor, earth pressure sensor and pore water pressure were embedded in the slope. The sensor was used to analyze the experimental phenomenon. The results show that the influence of the reservoir water level fluctuation is mainly concentrated at the foot of the front edge of the landslide, and the rapid decline of the reservoir water level has a significantly greater effect on the landslide deformation than the increase of the reservoir water level; The mechanical response of the slope body has a hysteresis, and the effective soil stress increases when the reservoir water rises, the anti-sliding force of the sliding belt increases, and with the increase of the rising rate, the penetration force directed into the slope is larger, which is conducive to the stability of the landslide; Under the condition of the reservoir water level, the deformation and failure mode of the Shiliushubao landslide is sorted as: original slope → Erosion and erosion expansion at the foot of the slope → formation and expansion of the fissure at the foot of the slope → formation of the fissure on the slope surface → local slump, which is a hydrodynamic pressure landslide. The test revealed the deformation mechanism under the condition of reservoir water level, and provided a reference for the study of similar landslides.

The underground powerhouse of Henan Wuyue Pumped Storage Power Station has a complex structure of caverns. The main powerhouse has a maximum span of 26.0 m and a height of 55.1 m, which is a large underground chamber. The rock mass structural planes are developed and the strength is low. The fault F1 runs through the three powerhouse, and the safety problems are prominent. The stability of surrounding rock after excavation should be analyzed. Therefore, FLAC^3D program was used to establish the geological model. The BSA-BP neural network was used to calculate the initial in-situ stress field of the area. And then the excavation of underground powerhouse was simulated. The stress field, displacement field and plastic zone development and distribution law of surrounding rock were analyzed. The results show that the surrounding rock of underground powerhouse caverns group is basically stable. However, local deformation and failure may occur in the fault development area and at both ends of the busbar hole. The research results can provide guidance for the design and construction of the project, and provide some reference for similar projects.

Based on Hopf bifurcation theory, the stability of pumped storage power station considering asymmetric water passing system is studied. Firstly, the mathematical model of the speed regulation system of the pumping and storage unit of the one-pipe two-machine asymmetric water passing system with the upstream surge chamber is established. On this basis, the Hopf bifurcation analysis is carried out to obtain the theoretical stability region of the speed regulation system, and the dynamic response characteristics of the unit under different control parameters are analyzed to verify its theoretical stability region. Furthermore, the multi-scale oscillation characteristics and its generation mechanism of the dynamic response of a pipe double pump storage unit are revealed. Finally, the influence laws of flow inertia time constant, turbine inertia time constant and surge chamber time constant on system stability are explored. The results show that the Hopf bifurcation of the speed control system of the pumping and storage unit of the one-pipe two-machine asymmetric overflow system with the upstream surge chamber is supercritical, and its stability region is determined by two bifurcation lines; The hydraulic interference between the surge chamber and the units makes the response characteristics of the units show obvious multi-scale oscillation characteristics; Larger flow inertia time constant and smaller turbine inertia time constant are beneficial to system stability, and the influence of surge chamber time constant on system stability presents saturation characteristics. The research results have important guiding significance for the intelligent control of pumping and storage units and the design optimization of water passing system in power stations.

UHV DC wall bushing is the neck-jamming technology of China’s power grid. At present, not only its core design and manufacturing technology still have many difficulties to be overcome, but also the state monitoring technology of its equipment operation is also a hot issue. This paper explores the application of an on-line monitoring technology based on vibration signals in UHV DC wall bushings. On the basis of analyzing the structure and common faults of UHV DC wall bushings, theoretical simulation research is carried out. It is found that when the outdoor insulation or inner insulation of the UHV DC wall bushing is damaged, the fundamental characteristic frequency of the bushing changes significantly. Afterwards, this paper carried out fault simulation and vibration tests on the cracking of capacitor core and the rupture of silicone rubber shed of the 800 kV UHV DC wall bushing. The results show that the fundamental characteristic frequencies of the bushing under different fault conditions are quite different. Therefore, the use of vibration monitoring technology can effectively identify the faults of UHV DC wall bushings, which can provide technical reference for UHV engineering construction and operation and maintenance personnel.

For the long-distance water supply project where the pump station pressurizes before the high point and gravity flows after the high point, when the end valve is closed in a straight line in case of power failure in an accident, a longer valve closing time is required to meet the pressure control standard, which virtually increases the scale of the protective measures and increases the investment. In order to solve this problem, a broken line valve closing rule is proposed to reduce the volume of protective measures while optimizing the pressure. The characteristic line method is used to check each scheme through FORTRAN programming, and the general rule is summarized by analyzing the influencing factors of the main parameters. The case results show that the broken line valve closing can reduce the volume of protective measures and reduce the project cost compared with the straight line valve closing within the same valve closing time under the premise of ensuring that the pressure meets the requirements.

The expansion of cities and towns has caused a large amount of waters to be compressed, occupied or even disappeared, and the risk of floods in the region has increased sharply. This study is based on Hengyang, a typical city in midstream of Xiangjiang River. Based on expansion speed index and intensity index of Xiangjiang midstream from 2001 to 2016, the linkage relationship between the two is quantitatively analyzed, and the response of water system change under the background of urban expansion is analyzed. The results show that the urban development in midstream of Xiangjiang River can be divided into three stages. The urban expansion is characterized by a high speed and then a low intensity. During the study period, the total number of river systems showed a declining trend, and the channel morphology showed a shrinking state. The change of the structure of river systems was more severe than the change of the number. The basin with few river systems and single structure had a sharp decline. Urban expansion has a close relationship with the change of river system, and has a greater impact on the change of the number of river systems. And it is highly related to the basin with few water systems and single structure. It can be seen that human activities such as urban construction and expansion should minimize the adverse impact on such watersheds.

To address the challenges in oil leakage image recognition of peak regulation power equipment, a new method is proposed by introducing logical rule discrimination strategy into the task of image recognition. The technology of histogram equalization is adopted to improve original image. Then Mask RCNN network is introduced to obtain the preliminary location and contour information of storage device, ground and suspected oil area. Based on the above information, positional relationships between objects are judged, and logical expressions are adopted to determine the oil leakage area. Example analysis is conducted based on filed images of peak regulation power equipment. The results indicate that the proposed framework solves the problems in oil leakage area recognition, largely boosting model performance.

In the weak current network, due to the large impedance characteristics of the power grid, the impedance parameters in the line change the key parameters of the rectifier control, affecting the overall performance of the rectifier, which may lead to the unstable output of the rectifier, and the output presents the characteristics of sub-synchronous oscillation. On the basis of not increasing the hardware compensation system, this paper proposes a control strategy that can effectively suppress the sub-synchronous oscillation. Based on the mathematical model, the AC current component of the sub-synchronous oscillation is extracted through the low-frequency filter. After d/q transformation, the d/q current component of the sub-synchronous oscillation is PI closed-loop controlled. The output value of the PI regulator of the subsynchronous oscillation component is decoupled and compensated, and then multiplied by the compensation coefficient to obtain the d/q compensation component of the voltage. The output of the original current inner loop is compensated. A simulation and test results show that the control strategy is effective and feasible, which can suppress sub-synchronous components.

With the continuous accumulation of dam deformation monitoring data and the continuous increase of deformation measuring points, it often takes a lot of time to predict all deformation measuring points, which is easy to cause the problem of untimely feedback. Therefore, the fuzzy C-means clustering algorithm (FCM) was introduced to partition the dam according to the similarity of deformation laws. The whale optimization algorithm (WOA) was used to optimize the parameters of long short-term memory neural network (LSTM), and a dam deformation prediction model based on FCM-WOA-LSTM was established. The measured deformation data of a concrete double-curvature arch dam was used as sample data for prediction, and the prediction results were compared with those of LSTM model and SVM model. The results show that the average absolute error (M_MAE), mean square error (M_MSE) and root mean square error (R_RMSE) of the prediction results of FCM-WOA-LSTM model are the smallest among the three models, and the three evaluation indexes of the fitting section are close to those of the prediction section, respectively. Compared with the existing models, the FCM-WOA-LSTM model has higher prediction accuracy and better applicability.

In order to study the influence of high tidal current velocity on the dynamic characteristics of horizontal axis tidal turbine under free wave conditions, STAR-CCM+ was used to establish a numerical calculation method for the hydrodynamic characteristics of tidal energy turbines under sea wave conditions. The law of wave influence on the rotation of tidal energy turbines and the characteristics of wake flow generated during the rotation were obtained. The results show that the amplitude and frequency of the angular acceleration of the tidal energy turbine are affected by the waves, but the fluctuation amplitude is less than the wave amplitude, the variation frequency is higher than the wave frequency. The wake flow produced by the rotation of the hydraulic turbine will make the flow field around the next hydraulic turbine more chaotic, and will have an impact on the blade rotation, turbine shaft load and energy utilization efficiency. Based on the analysis of the changing trend of pressure fluctuation, it is considered that the wake flow has little effect on the fatigue damage of hydraulic turbine.