The technology for diagnosing singlephase grounding faults in mediumvoltage distribution networks is of significant importance for enhancing the operational safety and economic efficiency of the system. In light of the current scenario where a large number of distributed generation sources are connected to the distribution network, this study analyzes the impact of distributed generation on singlephase grounding fault currents. It proposes a method for identifying the types of singlephase grounding faults and introduces a fault section location technique utilizing harmonic injection from adjustable arc suppression coils. Upon the occurrence of a singlephase grounding fault in the distribution network, the type of fault is first analyzed based on the characteristics of the zerosequence voltage and phase voltage. Subsequently, the filtering device of the adjustable arc suppression coil is temporarily blocked, allowing the harmonic current from the coil to be briefly injected into the grid. The system's FTU and DTU components analyze the third harmonic content in the zerosequence current. The presence of the third harmonic is used as a criterion to accurately determine whether the detection point is on the fault path, thereby achieving fault section location. A 10 kV distribution network simulation model under various grounding conditions was constructed and analyzed using EMTP/ATP software. The simulation results demonstrate that the aforementioned method effectively reduces the grounding current and achieves a section location accuracy of over 95%. This validates that the proposed method is suitable for both metallic grounding and grounding through transition resistance, meeting practical application requirements.

Due to a large area of heat absorbing surfaces and effects of uncertain windy condition, both the convective heat loss and solarthermal conversion efficiency of cavity receivers were unsteady. In order to reduce effects of wind on the cavity receiver performance, a novel cavity receiver design which had a windshield on its opening was investigated in the present study. The windshield could reduce the fluid flow disturbance inside the cavity, so that the convective heat transfer between the heat absorbing surfaces and ambient air were weakened, and the convective heat loss of the cavity receiver would be reduced. A solarthermal coupling numerical model was established firstly, and then effects of windshield material and wind were studied. The results showed that the material of windshield had a big influence on the receiver convective heat loss, and the convective heat loss would increase with a solid wall windshield, while with a porous material windshield, the convective heat loss would decrease. The pressurejump coefficient and thickness of the porous material windshield were key factors affecting its performance. As the pressurejump coefficient increased, the optimal thickness decreased. For the optimal pressurejump coefficient and thickness, the convective heat loss could be reduced by about 53.0%. The results in the present study could provide theoretical and technical guidance for design of cavity receivers.

In this study, a multiphysical field coupling model of metal hydride hydrogen storage reactor (MHHSR) based on cylindrical heat exchanger was established. The influence of the geometric shape and position of the cylindrical heat exchanger on the hydrogen absorption performance of the reactor was investigated, and the mathematical model was developed. The optimal position of the heat transfer structure was obtained, and the characteristics and intrinsic mechanisms of heat and mass transfer in the alloy bed during the hydrogen absorption process were explored. Additionally, based on the area of the temperature differential zones among different layers, the uniformity of heat transfer in multilayer beds was analyzed. The research results showed that when the embedded heat transfer ring was located at 0.62R of the alloy bed, the hydrogen storage reactor achieved 90% hydrogen capacity within the shortest time. By comparison to the central heat exchange tube structure and the external heat exchange jacket structure, there was a time reduction of 76.3% and 60.7%, respectively. Different types of heat exchanger structures caused differences in the thermal mass transfer characteristics of the alloy bed, which changed the evolution modes of the bed's reaction interface area and moving speed, ultimately affecting the reactor's hydrogen absorption performance. When multiple independent reaction bed layers existed in the reactor, a smaller temperature difference region area among different bed layers resulted in more uniform heat and mass transfer and higher energy efficiency of heat exchanger structures.

Through establishing the torsional dynamic model of wind turbine gear transmission system, a method of dynamic parameter identification and fatigue damage prediction of wind turbine gear transmission system based on mechanism model and operating state is proposed, and the dynamic response and fatigue damage prediction effect of wind turbine gear transmission system under different gear wear states are analyzed. The research results indicate that the identified gear rotational inertia and meshing stiffness are in good agreement with the target values; The contact fatigue damage of the same gear is generally greater than that of bending fatigue damage, and gear wear can exacerbate the fluctuation of dynamic meshing force and increase fatigue damage. Under different gear wear states, the estimated values of system dynamic response and gear fatigue damage are in good agreement with the target values.

For the identification of wind turbine blade defect types. First, a physical models of thermal reflection coefficients of the defect were established. A new identification method of wind turbine blade defects based on the combination of thermal signal reconstruction technology and thermal reflection coefficient of defective materials was proposed. Then, the wind turbine blades specimen containing (bubble, impurity, wrinkle) was performed by the longpulse infrared thermogaphy technology. The experiments were subjected to nondestructive testing for two heating times. It is found from the experiments results that the defects of wind turbine blade specimen could identify by longpulse infrared thermal imaging technology at temperature cooling process. Experiments have proved that the physical models of the thermal reflection coefficient are feasible. The error between the test results and the prediction results is very small.

Due to the wide variety of wind farm equipment and complex operating environment, it is usually unattended and difficult to find faults in time. The traditional inspection method takes a long time and has low identification accuracy. As a result, the fault is not handled in time, which affects the stable operation and power generation efficiency of wind farms. Therefore, a robot centralized inspection scheme based on improved pattern recognition is proposed for unattended wind farm groups. For transformer faults, equipment temperature anomalies and gearbox sound anomalies in wind farms, BP neural network algorithm, fuzzy pattern recognition algorithm and empirical mode decomposition algorithm are used to carry out inspection, and the proposed method is tested experimentally in a large wind power station. The results show that the proposed method can realize the inspection of various faults in wind farms. The first time to obtain the fault signal, to avoid the occurrence of security accidents; The recognition accuracy rate remains above 92.3%, and the recall rate and F1 score are also better than the comparison method, indicating that the proposed method is more comprehensive in identifying fault samples and can detect faults more effectively.

With the development of distributed generation technology on the user side, there is an urgent need to improve the reliability and economy of community power consumption. This paper introduces a community operator to manage the energy of the community and constructs an energy trading model centered on the community operator with energy storage devices. Firstly, considering the shortcomings of the existing pricing mechanism, an improved supplydemand ratio pricing mechanism is proposed to promote energy sharing in the community. Then, by coordinating energy storage devices and considering their loss costs, an online energy scheduling algorithm with low complexity is proposed based on the improved Lyapunov optimization method to maximize the revenue of the community operator under the premise of meeting the power consumption demand of the community. Theoretical analysis results show that the proposed algorithm can achieve the asymptotically optimal value of the optimization objective based only on the current system state, without the need for prior statistical knowledge of photovoltaic output, user load demand, and realtime electricity prices. Simulation results show that compared with reinforcement learning algorithms and greedy algorithms, the revenue of the community operator under the algorithm proposed in this paper is increased by 5% and 20.9% respectively, effectively promoting the local consumption of photovoltaic power.

The development of highfrequency AC distribution systems poses new challenges to the requirements of inverters. Traditional inverters are no longer suitable due to their complex structure, high switching frequency, and lack of boost capability. Based on this, a novel singlephase capacitor self balancing five level inverter topology is proposed. This topology achieves five level output through a series parallel mechanism combining capacitors and power sources, and has the advantage of capacitor self balancing; Improve transmission efficiency by simplifying the structure and reducing switching frequency; Using specific harmonic elimination methods to further reduce output harmonic distortion. This article introduces the working principle of inverters and the calculation method of related parameters, and conducts simulation verification. The results indicate that the theoretical analysis is correct, indicating that the inverter is suitable as a power side device in the highfrequency field.

Considering the lack of pumped storage power plant smoke regularly send scheduling flexibility, system problem such as carbon emissions calculation is not comprehensive, is put forward based on the permeability of pumped storage power station high energy low carbon power system optimization scheduling method, introduced the thermal power unit desulfurization, climbing to produce carbon emissions calculation factor, system of carbon emissions calculation model is established. Through the Xinjiang power grid and Fukang pumped storage power station actual data, considering different grid characteristics of winter and summer, simulation of the pumped storage power station in the high permeability of the power system operation, system for carbon emissions, abandoned electric rate etc. Comparative study the pumped storage power plant smoke regularly send, low carbon's influence on the system optimal operation way, and analyzes the causes of different influence, It is verified that the proposed lowcarbon optimal scheduling method can effectively reduce the carbon emission and the power discard rate of new energy, improve the positive and negative reserve capacity of the system, and smooth the power supply output fluctuation. This paper provides an analysis method for lowcarbon power supply dispatching in areas with high and new energy penetration, and puts forward some suggestions for the subsequent construction and development of Xinjiang power grid pumped storage power station, and provides reference for the selection of dispatching mode after the completion and operation of Xinjiang Fukang pumped storage power station.

Wave energy resources, particularly the incident wave power density, are critical to the design and evaluation of wave energy conversion systems. Based on the operational principles of the Eagle wave energy converter, this study analyzes the incident wave power density under realsea conditions, develops a methodology for measuring input wave energy power, and establishes an input wave power model. Utilizing wave data including significant wave height, mean period, and wave direction collected over 217 consecutive hours from June 8 to 18, 2016, during the realsea state testing of the "Wanshan" Eagle wave energy converter, the realtime input wave energy power was measured and compared with published literature data. The results indicate that the measured values are generally lower than those reported in the literature, and the temporal variation in wave power is more gradual, providing a more accurate representation of actual marine environmental changes. Consequently, the proposed incident wave power measurement method can offer precise and reliable reference data for the design and performance assessment of wave energy conversion systems or wave power stations.