Using photovoltaic (PV) energy to produce hydrogen through water electrolysis is an environmentally friendly approach that results in no contamination, making hydrogen a completely clean energy source. Alkaline water electrolysis (AWE) is an excellent method of hydrogen production due to its long service life, low cost, and high reliability. However, the fast fluctuations of photovoltaic power cannot integrate well with alkaline water electrolyzers. As a solution to the issues caused by the fluctuating power, a hydrogen production system comprising a photovoltaic array, a battery, and an alkaline electrolyzer, along with an electrical control strategy and energy management strategy is proposed. The energy management strategy takes into account the predicted PV power for the upcoming hour and determines the power flow accordingly. By analyzing the characteristics of PV panels and alkaline water electrolyzers and imposing the proposed strategy, this system offers an effective means of producing hydrogen while minimizing energy consumption and reducing damage to the electrolyzer. The proposed strategy has been validated under various scenarios through simulations. In addition, the system’s robustness was demonstrated by its ability to perform well despite inaccuracies in the predicted PV power.

Accurate measurement of overvoltage in power grids is of great significance to study the characteristics of overvoltage and design of insulation coordination. Based on the research of D-dot voltage sensor, we designed a Dual-Differential D-dot overvoltage sensor. In order to quantify the structural parameters of the sensor, improve the performance and measurement accuracy of the sensor. The Field-Circuit Coupling method was proposed to be used in the parameter design of D-dot overvoltage sensor. The joint simulation of space electromagnetic field model and equivalent circuit model of the Dual-Differential D-dot overvoltage sensor was established with the finite element simulation software Ansoft Maxwell and circuit simulation software Simplorer. Finally, the actual sensor was manufactured. A test platform was built to verify the steady-state and transient performance of the sensor. The results show that the Dual-Differential D-dot sensor has excellent steady-state and transient performance, the error of phase and amplitude are small, and the sensor can achieve the non-contact measurement of power transmission line. Simultaneously, the rationality of the Field-Circuit Coupling method was further verified.

Inter-Turn Short Circuit (ITSC) faults do not necessarily produce high temperatures but exhibit distinct heat distribution and characteristics. This paper proposes a novel fault diagnosis and identification scheme utilizing an improved You Look Only Once Vision 8 (YOLOv8) algorithm, enhanced with an infrared image slicing-aided hyper-inference (SAHI) technique, to automatically detect ITSC fault trajectories in dry-type transformers. The infrared image acquisition system gathers data on ITSC fault trajectories and captures images with varying contrast to enhance the robustness of the recognition model. Given that the fault trajectory constitutes a small portion of the overall infrared image and is subject to significant background interference, traditional recognition algorithms often misjudge or omit faults. To address this, a YOLOv8-based visual detection method incorporating Dynamic Snake Convolution (DSConv) and the Slicing-Aided Hyper-Inference algorithm is proposed. This method aims to improve recognition precision and accuracy for small targets in complex backgrounds, facilitating accurate detection of ITSC faults in dry-type transformers. Comparative tests with the YOLOv8 model, Fast Region-based Convolutional Neural Networks (Fast-RCNNs), and Residual Neural Networks (Retina-Nets) demonstrate that the enhancements significantly improve model convergence speed and fault trajectory detection accuracy. The approach offers valuable insights for advancing infrared image diagnostic technology in electrical power equipment.

Contactless overvoltage measurement sensor has good foreground in the application of the power system, and however, the difference in the installation position of the sensor will directly affect the stability of the measurement system. Therefore, it is essential to improve the overall measurement effect by selecting an appropriate measuring point. In this article, first, we proposed a new self-decoupling method based on the simplified matrix with the position parameters of the measuring point and applied it in the measurement of three-phase transient overvoltage. Then, we obtained the 3-D electric field ( $E$ -field) distribution characteristic under the different simulated overvoltage signals and preliminarily analyzed the measuring effect of the various measuring points distributed in the axial and radial direction of the overhead line. Furthermore, we proposed the gradient optimizing method with a calculation and analysis process for the selection of the measuring point. Finally, taking the three-phase horizontal distributed transmission lines as an example, we calculated the voltage coefficient matrix at various selected points, estimated the uncertainty contributions, and accomplished the test through the overvoltage experimental platform. From the result, the relative amplitude error of the overvoltage signal measured by the sensor installed at the optimal measuring point is less than 3.50%, the relative expanded uncertainty of the test at the optimal point is about 8.74%, and the values are much smaller than those of other measuring points, which proved the effectiveness of the proposed method.

It is essential to carry out an AC voltage withstand test after GIS extension and maintenance. At present, the common methods of GIS AC withstand test include double isolation gap, reduce the test voltage, and narrow test range. These methods generally have some defects: such as complex test processes, all bus de-energized, some apparatus failed to test, unreliable test results and so on. This paper presents a distinctive GIS AC voltage withstand test method. The method controls the phase-frequency parameters of the test voltage so that it maintains the same phase-frequency relationships as the in-service bus voltage during the process of testing. In this situation, the GIS can carry out an energized AC voltage withstand test. The process of AC withstand voltage test method based on phase-frequency control (PFC) is introduced in detail, and the feasibility of this method is verified. The phase difference margin of the PFC method is optimized through simulation and numerical calculation, and a variety of protection measures are proposed to ensure the safety of the test process. The proposed PFC AC voltage withstand test method will not affect the in-service bus and has great practical application value for the field GIS AC voltage withstand test.0_F.