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Non-intrusive transmission cable monitoring is the latest advanced measurement technology for smart grids. It only samples the voltage on a certain part of the transmission cable, and uses intelligent algorithms to identify the quality, which has obvious advantages of low construction and maintenance costs. This paper established a model based on multi-channel data fusion and transfer learning to classify the quality of transmission cable. First, we used the ANSYS Maxwell simulation platform to obtain ten kinds of specific fault data, which solved the time cost of manual labeling. Then, we performed multi-channel data fusion on the original data, which strengthened the expression of important features and was more conducive to the training of the model. Next, we used Depthwise Separable Convolution (DSC) to speed up the learning of the model, and improve the accuracy of the classification. Finally, we transferred the model trained with simulation data into the real scene, realized the transfer from multi classes to two classes, the effectiveness was proved in experiments. The accuracy of the model built in the article to classify the quality of the transmission cables is 98.1%.

In this work, the boron nitride (BN) nanosheets were dispersed in natural esters to fabricate the dielectric nanofluid. Microstructures and chemical compositions of the nanosized BN are determined. The stability, viscosity, and thermal conductivity of the BN nanofluid, were obtained. And the dissipation factor, electrical conductivity, and relative permittivity of the BN nanofluid, were measured. The ion mobilities and migrating times of the nanofluid were measured under different volumetric fractions of BN nanosheets and temperatures. Results show that the electrical conductivity and dissipation factor of the nanofluid decreased by 54% and 48% with the addition of only 0.1% of BN nanosheets under 110°C. Both the half‐reduced carrier mobility of the nanofluid and the declined ion concentration by blocking of BN nanosheet contributed to the exponentially reduced electrical conductivity and enhanced dielectric performances of the BN nanofluid. The suppression coefficient k is proposed to quantitatively describe the hinder effect of ion migration in nanofluids by 2D BN nanosheet. Results provide a strategy to design and develop advanced nanofluids with low‐dielectric loss by aids of surface adsorption of ion and steric hindrance of 2D nanosheets.

Vegetable insulating oil is a common kind of synthetic liquid insulating medium, which is usually applied in high voltage electrical equipment, such as transformers. At present, some mineral insulating oil has already been replaced by the eco-friendly vegetable insulating oil. Typically, the eco-friendly vegetable insulating oil not only possesses good electrical performances but also owns great biodegradability and high flash point. However, there will be impurities in any kind of vegetable insulating oil inevitably, and those impurities will have a serious influence on the properties of insulating oil. Metal-organic framework (MOF) has potential to be used as adsorbent because of its special micropore structure and large specific surface area. Meanwhile, it is convenient to prepare various of MOFs and control their structures. Nowadays, MOFs are usually used in the field of medicine delivery, chemical catalysis and gas adsorption. Nevertheless, utilizing MOF as a kind of adsorbent in vegetable insulating oil is seldom reported. In this paper, a typical MOF named zeolitic imidazolate framework-67 (ZIF-67) was prepared and used in the research. The microstructure of ZIF-67 was observed under the scanning electron microscope (SEM). The chemical properties of ZIF-67 were characterized by the X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Also, ZIF-67 was used as an adsorbent to treat the aged vegetable insulating oil. Results showed that the dielectric loss of aged vegetable insulating oil can be reduced by 46.7%, and the water and acid value of the aged vegetable insulating oil could be decreased gently at the same time. This approach provides a possible solution to improve the performance of vegetable insulating oil for the high voltage electrical system.

Along with the social and economic development and continuous increasing of electrical load, power distribution network has its scale continuously expanded, and more and more distribution transformers go deep into the urban residential areas, leading to increasingly serious vibration and noise problems. Relying on a typical 35 kV distribution transformer, a vibration mode test was done on the tank structure of the distribution transformer, and PolyLSCF fitting method was adopted to obtain the first 10-order modal shape in this paper. Meanwhile, finite element model was built for distribution transformer tank, and contrastive analysis were done in combination with the measured data to obtain the rules of influence on vibration mode of distribution transformer by tank wall thickness. The vibration characteristics acquired by measured mode of distribution transformer are consistent with those obtained by numerical simulation, and the central vibration amplitude of the tank is the maximum. Along with the increase of wall thickness, the low-order mode of the tank structure shows insignificant change, and high-order mode frequency reduces, thus providing measured data reference for optimizing the tank structure of distribution transformer.

Aiming at the typical AC/DC parallel transmission lines which have been put into operation in China, the electromagnetic environment of parallel transmission lines is monitored and the interaction between AC and DC electromagnetic environment is analyzed. Monitoring results show that: The electromagnetic environment of UHV AC/DC parallel transmission lines meets the corresponding national standard limits. UHV DC transmission line has little influence on power frequency electromagnetic field, which is mainly affected by distance and wire height to ground. UHV AC transmission line may have a certain impact on DC composite field strength, and wind speed will have a greater impact on DC composite field strength.

This paper proposes a new nature based on deep deterministic policy gradient for deep reinforcement learning in continuous state and action space, which can greatly accelerate the emergence of artificial intelligence training and solving problem: state-action permissibility. The proposed method is integrated into the latest DDPG algorithm to guide its training and is applied to solve the lane keeping (steering control) problem in autonomous driving or automatic driving. Finally, the TORCS which is the open racing car simulator simulation software builds various simulation environments, including different tracks to verify the effectiveness of the algorithm. The results show that the proposed method can significantly speed up the algorithm training speed of the lane keeping task.

To save land resources, the construction of the high-voltage direct current (HVDC) and high-voltage alternating current (HVAC) hybrid transmission lines in the same corridor is inevitable. To provide suggestions for the construction of the AC/DC parallel lines, the hybrid ionized field of AC/DC transmission lines was calculated by the meshless local Petorv&ndash, Galerkin (MLPG) method for the first time. In this method, the radius of local sub-domain is adjusted to the nodes close to the global boundary, but not exactly on the boundary. It can avoid the boundary integral, as well as having simplified calculation. The method was validated by comparing with measured results and calculation results. The MLPG method is beneficial to obtaining high-precision results by constructing the more complex shape function. Finally, a field distribution of the parallel line of about &plusmn, 800 kV DC/500 kV AC was calculated. Moreover, the influence of different parallel spacing and AC voltage level on the hybrid ionized field was analyzed, which provides theoretical basis for real parallel lines design.

The corrosion of grounding grids can result in a grounding accident of a power system, and much attentions has been concentrated on the method used to detect a corrosion fault in a grounding grid, in which the methods of voltage measurement and magnetic field measurement are usually used. In this paper, a cycle voltage measurement method and L-curve regularization method are proposed to locate the faults in grounding grids. The L-curve method was used to select the appropriate regularization parameter, which can effectively balance the error and stability of the solution to the inverse problem. The uncertainty of the solution due to the ill-posed problem in the inverse problem has been well-solved. Experiments were conducted in a laboratory with two network types. In addition, a field experiment was carried out in a 110-kV substation. Both of the results showed that the method can effectively locate a branch fault with a single branch and multiple branches in the grounding grids.

Insulating vegetable oils are environment-friendly and fire-resistant liquid dielectrics. This paper presented a new type of high fire resistance transformer filled with insulating camellia oil. The main physical, chemical and electrical properties of insulating camellia oil were measured and compared with those parameters of mineral oil. A new type of sealing camellia oil filled transformer was designed. The performances of camellia oil filled transformer were tested. The test results indicated good insulation performances of camellia oil filled transformer. The temperature rise of an ordinary transformer which was filled successively with insulating camellia oil and mineral oil were tested. The results showed that the temperature rise of insulating camellia oil filled transformer is slightly higher than that of mineral oil immersed transformer, suggesting that the oil gallery structure should be improved and the heat resistant grade of insulation paper should be enhanced.

Expectation of loss is adopted to describe the potential risk of an information system in conventional risk assessment methods which can not reflect the nonlinear property of loss. To solve the problem, this paper proposes a loss utility function and a possibility utility function to describe the loss and possibility of risk respectively, together with the concept of risk utility. With AHP (analytic hierarchy process) and risk utility combined together, this paper manages to conduct a relatively comprehensive risk assessment of the system and demonstrates its effectiveness in an example in practice.

Based on a 3-D inhomogeneous simulative body torso model, the influence of various boundary conditions on inverse recovered epicardial potential maps (EPM) was studied by boundary element method (BEM). The result shows that the precision of EPM calculated under incomplete boundary conditions will meet the clinical requirements, as long as the incomplete boundary conditions still contain the extremum area which often appears at the breast area.

Proposes a closed-loop approach for the solution of the electrocardiographic inverse problem. An optimization algorithm is designed to recursively refine the inverse solutions. This method allows us to obtain detailed information on cardiac electric events under a realistic and inhomogeneous heart-torso model. Simulation results show that it is feasible to identify and localize electric events for patients suffering from the old anteriorseptal and the old inferior myocardial infarction.