关键词：
high-impedance grounding fault;fault area isolation;waveform characteristics;polarity difference
摘要：
To address challenges in locating high-impedance grounding faults (HIGFs) and isolating fault areas in resonant grounding systems, this paper proposes a novel fault identification method based on coordinating a Peterson coil and a resistance grounding system. This method ensures power supply reliability by extinguishing the fault arc during transient faults with the Peterson coil. When a fault is determined to be permanent, the neutral point switches to a resistance grounding mode, ensuring regular distribution of zero-sequence currents in the network, thereby addressing the challenges of HIGF localization and fault area isolation. Fault calibration and nature determination rely on recognizing neutral point displacement voltage waveforms and dynamic characteristics, eliminating interference from asymmetric phase voltage variations. Fault area identification involves assessing the polarity of zero-sequence current waveforms attenuation during grounding mode switching, preventing misjudgments in grounding protection due to random initial fault angles and Peterson coil compensation states. Field experiments validate the feasibility of this fault location method and its control strategy.
作者机构：
[Ma, Rui; Zhou, Yang; Zhu, Siqiao; Zhou, Y] Changsha Univ Sci Technol, Sch Elect & Informat Engn, Changsha 410114, Peoples R China.;[Zhong, Shiyuan] State Grid Jiangxi Elect Power Co Ltd, Econ & Technol Res Inst, Nanchang 330006, Peoples R China.
通讯机构：
[Ma, R; Zhou, Y ] C;Changsha Univ Sci Technol, Sch Elect & Informat Engn, Changsha 410114, Peoples R China.
关键词：
5G base station;peak shaving;communication load;air conditioning load;optimize scheduling
摘要：
With the rapid development of the digital new infrastructure industry, the energy demand for communication base stations in smart grid systems is escalating daily. The country is vigorously promoting the communication energy storage industry. However, the energy storage capacity of base stations is limited and widely distributed, making it difficult to effectively participate in power grid auxiliary services by only implementing the centralized control of base stations. Aiming at this issue, an interactive hybrid control mode between energy storage and the power system under the base station sleep control strategy is delved into in this paper. Grounded in the spatiotemporal traits of chemical energy storage and thermal energy storage, a virtual battery model for base stations is established and the scheduling potential of battery clusters in multiple scenarios is explored. Then, based on the time of use electricity price and user fitness indicators, with the maximum transmission signal and minimum operating cost as objective functions, a decentralized control device is used to locally and quickly regulate the communication system. Furthermore, a multi-objective joint peak shaving model for base stations is established, centrally controlling the energy storage system of the base station through a virtual battery management system. Finally, a simulation analysis was conducted on data from different types of base stations in the region, designing two distinct scheduling schemes for four regional categories. The analysis results demonstrate that the proposed model can effectively reduce the power consumption of base stations while mitigating the fluctuation of the power grid load.
通讯机构：
[Fan, SS ] C;Changsha Univ Sci & Technol, Sch Elect & Informat Engn, Changsha 100024, Hunan, Peoples R China.
关键词：
Histograms;Lighting;Visualization;Substations;Reflectivity;Inspection;Image color analysis;Global and local enhancement;histogram equalization (HE);infrared thermal image quality improvement;Retinex;substation equipment
摘要：
Noncontact infrared detection is an effective way to diagnose substation equipment defects, but inclement weather conditions like haze and rainstorms produce low-quality infrared images, making it challenging to recognize equipment. To overcome this problem, a global and local contrast adaptive enhancement method is suggested. The global approach consists of the gray-level stretching Retinex (GLS Retinex) and the weighted truncated Gaussian histogram equalization (WTGHE). The GLS Retinex comprises gray-level stretching, fast-guide filtering, and parameter self-adjustment Retinex, which can be used to brighten dark images. The WTGHE contains Gaussian histogram calculation, truncated histogram equalization (HE), and weighted RGB fusion, aiming to handle blurred images. To significantly improve the quality of images in some detailed regions that cannot be handled by global enhancement algorithms, a local scheme called regional growth reenhancement is proposed, which includes multiseed region automatic selection and adaptive threshold growth criterion. The performance of the proposed technique is evaluated using over 1000 infrared thermal photographs of several substations under extremely difficult circumstances. The experimental results show that the novel strategy outperformed existing enhancement methods. The deep-learning detector also demonstrated the effectiveness of our proposed enhancement method for the improvement of detection precision.
摘要：
Accurate oscillation mode recognition and stability analysis based on big data are critical for the safe operation of wind turbine systems. This paper utilizes modern statistical and machine learning methodology to analyze the correlation between monitored wind turbine operation data and oscillation phenomena, and a system oscillation analysis and diagnosis method is proposed based on an improved association rule mining (ARM) model. Firstly, the oscillation modes in the power data are measured by the synchronous extraction transform. By improving the ARM model, a thorough study is conducted on the correlation between oscillation modes and variables such as wind speed, compensation degree, voltage fluctuation, etc. Finally, the component importance measure is used to optimize each element's risk weight calculation method relative to the system oscillation. The experiments demonstrate that the proposed association rule analysis method can effectively analyze the relationship between system oscillation phenomena and influencing factors and exhibits high diagnostic accuracy.
摘要：
油浸式变压器内部绕组的匝间纸绝缘受温度的影响会析出气泡,进而引发局部放电导致绝缘劣化。该文通过研究油纸界面的微观结构和气泡产生的物理过程,建立气泡演化的数值模型,结合气泡生长过程中的受力分析,得到了气泡在不同条件下的生长...展开更多 油浸式变压器内部绕组的匝间纸绝缘受温度的影响会析出气泡,进而引发局部放电导致绝缘劣化。该文通过研究油纸界面的微观结构和气泡产生的物理过程,建立气泡演化的数值模型,结合气泡生长过程中的受力分析,得到了气泡在不同条件下的生长规律。首先,基于Rayleigh-Plesset方程建立油纸界面处由气泡内压强主导的气泡生长过程。其次,根据理想气体体积定律与Hertz-Knudsen界面蒸发冷凝方程量化界面处水蒸气进入气泡的质量通量,并在此基础上建立气泡内压的控制方程。最后,求解获得了升温时油纸系统中气泡的生长曲线,并根据气泡生长时的受力分析得到了气泡脱离半径进而计算出气泡初始逸出温度(initial temperature of bubble escape,ITBE)。计算的气泡脱离半径与实验结果具有较好的一致性,此外预测的ITBE与实验结果的最小平均相对误差为1.11%。模型结果表明,纸中水分质量分数越高,气泡生长速度越快。而绝缘纸微观结构的变化主要通过影响气泡初始半径和气泡在界面处所受表面张力的大小,从而影响气泡的形成过程。收起
通讯机构：
[Yu, K ] C;Changsha Univ Sci & Technol, Sch Elect & Informat Engn, Changsha 410114, Peoples R China.
关键词：
Voltage control;Distribution networks;Circuit faults;Grounding;Arc discharges;Switches;Windings;Active voltage protection;arc suppression;medium-voltage distribution networks;single-phase ground fault;voltage flexible regulation
摘要：
Intermittent arc grounding faults are common in medium-voltage distribution networks, and the arc cannot be extinguished without assistance. The application of existing arc suppression methods is limited due to the problems of large compensation residual currents, complex control circuits and large short-circuit currents. Therefore, an active voltage-type grounding fault protection method for medium-voltage distribution networks with neutral point voltage flexible regulation is proposed. The line voltage opposite to the fault phase is extracted from the auxiliary side of the Dyn1 distribution transformer, and it is fed to the neutral point. By adjusting the Dyn1 transformer ratio to regulate the neutral point injection voltage size, the residual voltage is reduced to below the arcing voltage, the arc is no longer reignited, and the fault residual current is eliminated. The simulation results of PSCAD/EMTDC software and the field test results of the 10 kV true distribution network prove that this method can reliably achieve arc suppression.
通讯机构：
[Wang, Z ] C;Changsha Univ Sci & Technol, Sch Elect & Informat Engn, State Key Lab Disaster Prevent & Reduct Power Grid, Changsha 410114, Peoples R China.
关键词：
Distribution networks;Electromagnetic potential transformer;Ferromagnetic resonance;Resonance suppression;Flexible grounding
摘要：
When a single line-to-ground (SLG) fault occurs in a distribution network, ferromagnetic resonance is easily triggered by magnetic saturation of the potential transformer (PT) after the fault disappears. To solve this problem, a method is proposed for ferromagnetic resonance suppression (FRS) in distribution networks based on flexible grounding technology. A controllable voltage is injected at the neutral point of the distribution network through a flexible grounding device (FGD) to suppress the neutral point voltage (NPV) of the system to zero, quickly restoring the system to the normal operating state, preventing magnetic saturation of the PT core, destroying the conditions for ferromagnetic resonance in the system, and realising FRS. The proposed method provides a release channel for the charge accumulated in the line-to-ground capacitance, consuming the electromagnetic energy stored in the circuit. Various resonant conditions are simulated in a PSIM 9.1 environment to verify the FRS process and effect of the proposed method. The simulation results show that the proposed method can quickly achieve FRS with a good detuning effect, simple control and a high response speed.
期刊：
IEEE Journal of Radio Frequency Identification,2024年:1-1 ISSN：2469-7281
作者机构：
[Xue Li; Zhenqi Fang; Ruhua Zhao; Hong Mo] School of Electrical and Information Engineering, Changsha University of Science and Technology Changsha, China
