In order to realize the safe monitoring of the operation status of hydroelectric units and solve the problem of automated watch keeping, based on speech recognition technology, the normal status model of measurement points based on the operation monitoring information of generating units was established to implement abnormality detection. Firstly, the experimental data of the bearings of Western Reserve University were used to verify the correctness of the selected modeling method of deep convolutional neural network (CNN) and Gaussian mixture model (GMM). Secondly, a total of forty-two measurement points were arranged for the turbine set, and ten sensitive measurement points were selected for position classification based on the rise rate of RMS before and after overspeed. Then some data were selected as training data to get CNN model and unit sound features. The GMM model was obtained by further training. Finally, the scoring results of the test data were used to determine the machine operation status, i.e., the degree of deviation from the normal status was determined to achieve abnormal status detection. The experimental scheme was confirmed by manual annotation, thus verifying the feasibility of the method, which realizes the design of sound-based abnormality detection algorithm for hydropower units.

To improve the state detection effect of large supercritical generator rotor set, the RSO (Cyclic Periodic Electrical Impulse) detection method of large supercritical generator rotor set based on time difference calculation is designed. According to the principle of RSO detection method, the characteristics of time difference pulse signal are extracted. The detection model of coil short circuit is constructed according to the time difference characteristics of signal. Wavelet transform is used to denoise the time difference signal. Fix the rotor position and winding parameters are fixed to determine the fault position of the rotor set. Thus, the RSO detection of the rotor set of large supercritical generator unit is realized. The experimental results show that the difference between the detection results of the power spectrum amplitude of the initial rotor position, the rotor position at startup, the normal broken bar and the broken bar fault is small, which verifies the effectiveness of the proposed method.

In order to solve the problem that the new hydraulic gate is difficult to manufacture experiment and debug in the real environment, the historical gate operation data was analyzed and transmitted based on the digital twin simulation platform. The designed gate was analyzed through numerical simulation, and the overall stress and deformation changes of the gate with different sub-gate opening degrees under hydrostatic pressure were analyzed. At the same time, the overall vibration frequency changes of the gate under the action of air and fluid-structure interaction were analyzed. The flow state of the fluid domain at the sub-gates with different opening degrees was simulated. The results show that with the increase of the opening of the sub-gate, the stress value of the gate varies from 58 MPa to 67.5 MPa, and the deformation change is not obvious; Compared with the natural vibration frequency of the gate in the air, the fluid-structure coupling effect will appropriate reduce the natural vibration frequency of the gate; Different sub-gate openings will affect the flow state of the fluid domain, and increasing the opening will reduce the water velocity. The results provide some references for its actual operation, maintenance and optimization of gate performance.

In view of the serious problem of scouring under the sluice gate of the Tidal River, taking the Shanghai area as an example, from the perspective of operation and maintenance management, the scouring mechanism under the sluice and the optimization method of operation and maintenance management were explored. Through the flow state analysis and hydraulic jump formula derivation, the variation law among the water level, the critical water depth of the outer river and Froude number in front of hydraulic jump was revealed. The water level solution formula suitable for the operation and maintenance management of the tidal estuary gate was proposed. The results show that the water level of the outer river fluctuates greatly because the tidal estuary sluice is affected by tidal action; When the water level of the outer river is lower than the critical water depth, it should be prohibited to open the gate; When the Froude number in front of the hydraulic jump section of the outer river level is between 4.5 and 9.0, the drainage of the gate can be effectively exerted, and the erosion under the gate can be effectively reduced. The results can provide a reference for the operation and maintenance management of similar tidal estuarine gates.

To decrease the costs associated with wave energy conversion and improve the performance of wave energy converters (WECs), a multi-float WEC that also serves as a breakwater is proposed, and its hydrodynamic performance is explored through physical model tests. The control variable method was used to investigate the free water surface, the dynamic response of the floats, and the energy conversion of the device under different PTO damping loads and wave conditions. These tests allowed for an analysis of the wave energy capture, as well as the device’s ability to prevent and dissipate waves. The test results show that the device functions well as a breakwater, with an average transmittance of 0.48 under typical test conditions, meaning that less than a quarter of the wave energy is transmitted to the rear of the device. Moreover, the device can effectively convert wave energy, with K_e exceeding 20% within the range of 0.64≤kh≤1.39 under suitable PTO loads.

For the transmission line distributed traveling wave fault ranging system, this paper proposes a distributed fault location matrix algorithm of transmission lines based on traveling wave time difference information. The algorithm uses the principle of double-ended traveling wave ranging to construct the lower triangular fault location matrix by combining the monitoring node data two by two. The nature of matrix rank was used to select the fault point area and calculate the fault location distance simultaneously. The matrix zeroing algorithm was set to accelerate the find of matrix rank. The distance correction algorithm was set to improve the accuracy of positioning results. The applicability and reliability of the distributed traveling wave fault location matrix algorithm for transmission lines were verified by modeling and simulation with PSCAD and MATLAB software. The necessity of the corrected zeroing algorithm and the significant improvement of the distance correction algorithm on the fault location accuracy were demonstrated by comparison during the operation.

The low voltage winding interturn insulation fault of dry-type transformer is not easy to find directly through the appearance of the phenomenon, and is difficult to real-time monitoring, seriously affecting the safe and stable operation of power systems. In view of the lack of fault detection methods due to insufficient research on the electromagnetic characteristics of single-turn interturn short-circuit faults in low-voltage windings of dry-type transformers, and the difficulty in setting interturn short-circuit faults in practical projects, finite element simulation software was used to establish a field-circuit coupling model which is consistent with the actual dry-type transformer, and the accuracy of the model was verified under rated operating conditions. On this basis, the variation rules of electromagnetic parameters of short-circuit turns at different positions were explored when interturn short-circuit faults occur in low-voltage windings. The distribution of electromagnetic force on short-circuit turns when interturn short-circuit faults occur in windings at different positions was simulated. The results show that when the interturn short circuit occurs at different positions of the winding, the maximum magnetic density appears in the outermost short-circuit turn; the outermost short-circuit turn is subjected to the largest radial force, and the innermost short-circuit turn is subjected to the largest axial force. Therefore, it provides a theoretical basis for on-line monitoring and protection technology of dry-type transformer interturn insulation, which is conducive to the research and implementation of measures to improve short-circuit resistance.

New energy grid connection is easy to cause voltage fluctuation, frequency oscillation and other problems. For this, the paper adopts a frequency division control strategy of hybrid energy storage unit, which based on the storage of photovoltaic grid-connected system as the research subject, thus improving the dynamic stability of DC bus voltage, and proposes an improved virtual synchronous generator. According to the characteristics of flexible adjustment of inertia parameters, the virtual inertia and parameters are adjusted adaptively to suppress the frequency and power oscillation caused by the disturbance. Finally, a simulation model of photovoltaic storage grid-connection is established. It verifies that the proposed strategy can not only stabilize the DC bus voltage and supplement the power deficiency under different operating conditions. At the same time, it can slow down the sudden change of the system frequency and reduce the overshoot, showing good grid-connected performance.

To improve the accuracy of areal mean rainfall data and solve the problems of instability of least square estimation in runoff error correction based on dynamic system response curve, ridge estimation of rainfall error based on differential response was introduced based on least square ridge estimation. The calculation of the Xin’anjiang model was generalized a system. The method was applied in flood forecast error correction in Jianyang basin with 37 historical floods chosen as test samples. The results indicate that the ridge estimation of rainfall error based on differential response has obvious correction effects in Jianyang basin, which can improve the accuracy and stability of flood forecasting.

In order to explore the evolution of rainfall at multiple time scales, this paper takes the Changtan Reservoir in Jiaojiang River Basin as an example and classifies independent rainfall events based on rainfall data from 1960 to 2019. The evolution of rainfall event elements is discussed from four perspectives of rainfall event scale, seasonal scale, changes in annual trends and interannual decadal change. The results show that the extreme rainfall events has strong rainfall and long rainfall duration; The rainfall duration of typhoon rainy season is shorter and the rainfall intensity is greater than that of the plum rainy season, and the variation of rainfall distribution is greater; The annual trends of rainfall event elements are similar between the two stations during the plum rainy season, but the annual trends of rainfall duration and rainfall intensity are significantly different between the two stations during the typhoon rainy season; The rainfall events of the two stations in the plum rainy season have a good response to El Nino events, while the annual rainfall of El Nino/PDO- in the typhoon rainy season is abnormally small, which is prone to drought. El Nino/PDO+ annual rainfall is abnormally high and is prone to appear flood disaster.