bluuebunny/crossref_metadata_2025 huggingface dataset:
A Three-Dimensional Substation Reconstruction Method Based on Scenery Point Clouds
Authors: Chen Xuan , Zheng Xin , Xu Gang , Shu Zhihai , Ji Yamin , Xu Changfu
Published: July 2024

3D modeling is the technical foundation for 3D visualization of substations, and accurate 3D panoramic modeling of substations is the key to achieving intelligent operation and maintenance of substations. However, the reuse rate of the model is low, resulting in low system modeling efficiency and bad model accuracy, which cannot fully leverage the advantages of 3D real scenery reconstruction technology. To address the aforementioned problems, this paper proposes a basic process and method for constructing a 3D model of a substation based on point cloud data, and provides an example of 3D reconstruction of the substation, which is then validated from three aspects. The experiment shows that the proposed process and method can achieve complete and accurate 3D reconstruction of substations, with a detail completeness of 98% and an outer diameter error of only 0.13 mm for transformer bushing leads.
Controller-in-the-Loop Validation for Virtual Impedance-based Fault Detection Method in Grid-Connected Inverters
Authors: Deng Caibo , Xu Baihe , Xiong Yongkang , Yuan Le , Xu Zaide , Song Guanhong , Xia Yonghong
Published: July 2024

The high penetration of distributed energy resources and grid-connected inverters creates operation and protection challenges in distribution networks which have led to a need for advanced fault protection methods. Therefore, a virtual impedance-based short-circuit fault detection algorithm is proposed in this paper for grid-connected inverters in distribution networks which determines a short-circuit fault through measurement of the spectral change in system impedance at each harmonic frequency. Moreover, a controller-in-the-loop platform is also developed in this paper for verifying the proposed detection algorithm without jeopardizing the operation of distribution networks. By using the developed platform, real-time simulation on both grid-connected inverter and distribution network is carried out. The results have proven the effectiveness of the proposed method and theoretical analysis.
Temporal Scenarios-based Assessment of Maximum Hosting Capacity of Renewable Generation in Distribution Systems Considering ANM Techniques
Authors: Wu Zhize , Zhou Zhiwen , Zhang Gang , Zhang Xiaoyu , Dong Wenjie , Liu Yanle
Published: July 2024

Incorporating large-scale renewable distributed generation (RDG) into the power grid introduces significant challenges associated with the indeterminacy of the power system, significantly impacting the comprehensive integration and efficient utilization of the distribution network. This underscores the imperative to investigate scientific evaluation methods and mechanisms for enhancing the RDG absorptive capacity within the distribution network. In light of the stochastic and temporal characteristics inherent to RDG, a novel approach for assessing the RDG hosting capacity within distribution networks is proposed, taking temporal scenarios into account. This method optimizes the RDG output probability distribution model based on its temporal fluctuation change rule, and constructs RDG temporal scenario model by using scenario reduction technology. Subsequently, a temporal scenarios-based RDG hosting capacity assessment model is established, taking into account active network management (ANM) techniques. The effectiveness of the proposed methodology is substantiated through simulation results conducted on a modified IEEE 33-bus system.
The Uncertainty Evaluation of Determining the Trace H2S in SF6/N2 Insulating Gas Mixture by Cavity Ring-Down Spectroscopy
Authors: Gao Ruifeng , Zhu Min , Zhang Chaohai
Published: July 2024

H2S is one of the most important characteristic components of sulfur hexafluoride gas insulated electrical equipment. The detection of trace H2S is of great significance for early fault diagnosis of such equipment. Based on the 1578 nm wavelength distributed feedback diode laser (DFB-DL), cavity ring-down spectroscopy (CRDS) can effectively measure the concentration of trace H2S in SF6/N2 gas mixtures. Starting from the principle of methodology, this article establishes a mathematical model for evaluating the measurement uncertainty of CRDS and analyzes its sources of uncertainty: gas constant R1
, temperature T, Avogadro constant NA
, gas pressure p in the optical cavity, volume V of the optical cavity, speed c of light, the absorption cross-section parameter σ(ν)
of H2S molecules in the laser frequency ν, the ring-down time τ with absorption sample H2S and the ring-down time τ0
without absorption sample. After evaluating the uncertainty components, it was found that the main component was σ(ν)
and the secondary components were τ and τ0. The H2S content in the 80% SF6-20% N2 mixed gas measured is (7.64 ± 0.12) × 10−6 mol/mol.
An Optimized Operation Method for Integrated Energy System Based on Variable Operating Condition Characteristics
Authors: Pan Yi , Leng Xina , Wang Tao
Published: July 2024

An integrated energy system (IES), functioning as a multi-input, multi-output apparatus, incorporates diverse power conversion and storage device. Typically, the energy hub visually demonstrates its multi-energy coupling. However, traditional energy hub models tend to ignore the variable operating condition characteristics of conversion device, that is, the actual operation efficiency fluctuates with the load rate. Consequently, it results in constant coupling coefficients in the energy hub coupling matrix, causing discrepancies between the IES operating state and actual conditions, affecting the operation scheme’s economy. Therefore, this study focuses on IES optimized operation method, which is based on variable operating condition characteristics, incorporating conversion device operating efficiency and load rate relationships into EH models. Development of a dynamic energy hub (DEH) model that takes into account the variable operating condition characteristics of the conversion device, operational efficiency of the device is corrected in real time, and an optimal scheduling model is built with the objective of optimal IES economy, designing different scenarios for simulation and verification with an IES as an example. The study demonstrates that incorporating device operating condition dynamics into scheduling scheme effectively minimizes system expenses and enhances the system’s integrity and feasibility.
A Construction Method for Three-Dimensional Digital Model of Substation Equipments Integrating Grid Information Model
Authors: Chen Xuan , Zheng Xin , Xu Gang , Shu Zhihai , Ji Yamin , Xu Changfu
Published: July 2024

Building a three-dimensional digital model of a substation is a key technology for achieving intelligent operation and maintenance of substations. However, the widely used GIM technology currently has obvious shortcomings in spatial attribute correlation, and cannot meet the application requirements. This paper proposes a three-dimensional digital model modeling method for substation equipments, which improves the general standardization transplantation and spatial attribute association ability based on GIM. This method integrates the GIM data standard, establishes a mapping relationship between GIM model data and JSON instances, fully preserves the attribute information of the model, and can easily obtain a three-dimensional slice model of substation equipments. The feasibility of the proposed method was verified through experiments.
Intelligent Fault Diagnosis Method for Transformer Driven by Multiple Vibration Data
Authors: Luo Xinyue , Chen Fei , Lu Yuhong , Zhao Zhigao , Peng Yumin , Pang Jingwen
Published: July 2024

Early monitoring and early warning of transformer failure are crucial to ensure the safe and dependable functioning of the power system, as transformers are essential equipment within the system. On multivariate vibration data, this work presents a sophisticated approach for diagnosing faults in transformers which integrates entropy model and machine learning. Firstly, a new coarse-grained method is introduced into the improved multiscale fuzzy entropy to improve the disadvantage of the traditional entropy model with large entropy fluctuation under high-scale factors. Furthermore, the features of transformer multivariate vibration signals are extracted by the entropy model. Finally, the extreme learning machine is utilized to achieve efficient detection of transformer defects. This method provides a useful method reference for fault diagnosis of power equipment with multi-vibration signal, and has good reference value.
Safety Helmet Detection in Electrical Power Scenes based on Improved Lightweight YOLOv8
Authors: Li Zuhe , Huang Zhenwei , Chen Hongyang , Deng Lujuan , Wang Fengqin
Published: July 2024

To tackle the challenges of diverse targets, complex scenes, and partial occlusion in safety management during electrical field operations, the YOLO series algorithm, recognized for its exceptional accuracy and swift processing capabilities, has been applied to various scene detection tasks. To ascertain if workers have donned safety helmets and ensure the safety of electrical field operations, we propose a lightweight algorithm based on the improved YOLOv8 for constructing a digital safety helmet detection system. By incorporating the VoV-GSCSP module, we reduced model complexity, decreased computational load, and improved detection accuracy. Simultaneously, by combining the GSConv module, we enhanced the network’s feature extraction capability, enabling the network to adapt more rapidly and accurately to various complex electrical scenes, thereby strengthening the network’s robustness in safety helmet detection. Finally, we validated the effectiveness of the proposed model using the pre-existing dataset for safety helmet detection.
Research on Transformer Fault Diagnosis Based on Voiceprint Signal
Authors: Liu Guofeng , Gao Lingtao , Yu Lu , Yang Wei
Published: July 2024

As an important part of the power system, the operating status of the transformer will have a direct impact on the stability and reliability of the power system. In view of the problems of high diagnosis cost and low accuracy of diagnosis results in existing fault diagnosis technology, this paper takes advantage of the obvious difference between the voiceprint signal of the transformer under normal and fault operating conditions and applies it to transformer fault diagnosis, which can effectively reflect its internal working status and fault conditions, helping operation and maintenance personnel promptly discover equipment defects and locate fault causes. In order to accurately realize transformer fault diagnosis, this paper uses the improved hybrid frog leaping algorithm to optimize the fault diagnosis algorithm of support vector machine parameters for fault diagnosis, which further improves the accuracy of fault diagnosis and is of great significance for accurately identifying transformer fault states.
Simulation Study on Mechanical Vibration Characteristics of GIS Bus Misalignment
Authors: Wang Min , Zhao Shengnan , Zhang Qingjun , Jiao Hailong
Published: July 2024

Gas-insulated switchgear (GIS) has been widely used in power grid systems. The busbar is a crucial element within a GIS system, responsible for facilitating electrical connections between different GIS components. Any defects during manufacturing or improper installation procedures can lead to busbar misalignment, resulting in abnormal vibrations within the GIS. This study focuses on analyzing the mechanical vibration characteristics of GIS bus misalignment using a simulation model based on the finite element method for a 252kV GIS. When the busbar is misaligned and the conductor experiences an unbalanced force, it undergoes Coulomb forces at double the voltage frequency. Under normal or misaligned conditions, the conductor exhibits forced vibrations at the power frequency of 100Hz. However, when misalignment occurs, there is a coupling effect between electrodynamics and vibrations, causing the shell to display integer frequency vibration components.
Research on the Aging Judgment Method of Electrical Performance of C4F7N/CO2 Mixed Gases
Authors: Qi Geqing , Yuan Feng , Zheng Yue , Li Gang , Yang Songli , Zhang Miao
Published: July 2024

Perfluoroisobutyronitrile (C4F7N) gas exhibits favorable environmental characteristics and excellent electrical performance, which renders it a prominent subject of research in the development of new environmentally friendly insulation materials as a substitute for SF6 gas. In this study, the decomposition products of a gas mixture comprising 15% C4F7N and 85% CO2 were investigated within a 12kV ring main unit. A total of 140 arc tests were conducted on the gas mixture, allowing for the identification of the relationship between the generation of decomposition products and the number of arc tests. Through the determination of the proportional relationship between the different types and quantities of products, a novel method for assessing the extent of electrical performance aging in C4F7N/CO2 gas was developed, thus serving as a valuable reference for gas aging assessment. This study is of great significance for promoting the application of C4F7N/CO2 mixed gas in power systems.
Research on Evaluation Method of Water-blocking Powder Distribution Uniformity of Buffer Layer in HV Cable Based on Image Processing
Authors: Wu Zhaoguo , Li Yong , Wang Qian , Huang Huixian , Cai Zixiong , You Yang
Published: July 2024

High voltage (HV) cables are widely used in urban power transmission networks. The key component in HV cable, the buffer layer, has attracted lots of attention and more and more researchers are devoting to its material property evaluation and quality test techniques. A longitude water-blocking property evaluation method of buffer layer based on image processing is proposed in this paper. The microscopic images of the buffer layer are enhanced and morphologically processed. The area fraction method, entropy method, and fractal dimension method are used to evaluate the distribution characteristics of buffer layer water-blocking powder in binary images. This article innovatively proposes a more economical and convenient simulation method that can efficiently and accurately evaluate the waterproof performance of the buffer layer of high-voltage cables. With the proper use of the buffer layer, it can effectively protect the cables and improve the stability of power system operation.
Shared Energy Storage Scheme for Photovoltaic Energy Storage Power Supply System
Authors: Li Qiying , Xie Yumeng , Yang Lei , Yang Kun , Xu Dongsheng , Qiao Dongwei , Wang Shuyuan
Published: July 2024

While PV-battery hybrid grid integration has been recognized as an effective approach to enhance transient stability, the high operational and maintenance costs of energy storage systems constrain their reliability across various operating scenarios. To overcome this challenge, this paper takes the application of PV-battery subsystems in a distribution grid supply scenario as an example and conducts an in-depth analysis of the transient stability of PV systems during fault conditions. In cases where system demands are not adequately met, this research proposes a solution based on shared energy storage to enhance system supportability while maintaining economic feasibility. By appropriately allocating and sharing energy storage capacity, the system can better respond to sudden load fluctuations and fault conditions, ensuring a stable power supply. Simulation results demonstrate that the proposed shared energy storage solution significantly enhances the transient stability of PV systems during fault conditions, effectively mitigating the destabilizing effects of PV grid integration. Furthermore, from an economic perspective, this solution can reduce energy storage operation and maintenance costs, enhancing overall system sustainability. In conclusion, this study presents a feasible and effective support solution for the application of PV systems in distribution grids, providing valuable insights to advance the reliability and sustainability of clean energy sources.
Start-up and Transient Support Control of AC-DC Hybrid Distribution Networks with Distributed PV Access
Authors: Li Ke , Lin Yuqing , Li Guoliang , Wang Long
Published: July 2024

For AC-DC hybrid distribution networks, a large number of interconnecting converters connected to DC micro-sources and DC distribution networks in the distribution network provide a powerful aid for restoring power supply to the loads in the lost area after an accident by using the local power supply of the system, and at the same time, the power synchronisation control strategy provides a friendly power supply mode for the power supply of the interconnecting converters to the passive network. This paper analyses the start-up control of AC-DC hybrid distribution networks with distributed photovoltaic (PV) access under the scenario of interconnecting converter multi-machine co-operation in transferring power to a load area without a superordinate power supply; and puts forward a power synchronous control of interconnecting converter multi-machine co-operation to suppress power-frequency oscillation under faults of a distribution network without a superordinate power supply.
Power System Planning Based on Cost Correction with High-Penetration of Renewable Energy
Authors: Su Rong , Jiang Ying , Wang Leqi
Published: July 2024

The growing prevalence of renewable energy has led to a greater impact on power grid planning due to the inherent indeterminacy and variability in renewable energy output. The establishment of a power grid planning system that can effectively accommodate large-scale renewable energy generation holds significant practical importance. Given the vast magnitude of optimization decision-making, the number of scenes and time granularity in the planning model are limited, and its cost data cannot reflect the impact of considering renewable energy with high penetration, resulting in inaccurate planning scheme. Then some conditions after operation simulation may exceed the planning expectation or cost a lot. Based on the problems, this paper proposes a planning-oriented cost model parameter feedback correction method based on the planning scheme simulation data. The planning scheme is simulated to get simulation data, which is subsequently used to compute more precise setup parameters. According to these parameters, a more accurate planning scheme is obtained. Finally, combined with an example, the simulation results of the conventional power grid planning model and the planning model with cost correction are compared, and the rationality and effectiveness of the proposed method are verified.
Research on lightning strike location by OPGW optical sensing based on extreme sliding window and wavelet
Authors: Yang Jie , Gao Xiang , Hou Jun , Chen Xianda , Shao Shuai
Published: July 2024

Lightning strikes usually affect the safe use and normal operation of the power grid. It is crucial to accurately identify and position the lightning strikes. The lightning current on OPGW near the lightning strike point and the modulated lightning intensity signal waveform were simulated. The polarization state signal of Faraday optical fiber will mutate when it is struck by lightning. The extreme value unit sliding window energy method was used to extract the initial time window of the signal after a lightning strike, and the three alternative windows with the maximum energy were determined. Then the maximum wavelet coefficient is determined to be the first wave time point of the struck signal. Simulation analysis and engineering field application show that the optical polarization signal characteristic of OPGW can be used to accurately locate the lightning strike point, which can meet the needs of practical engineering applications of power systems.
Two-layer Optimization-Based Capacity Allocation Method of Integrated Energy Systems
Authors: Xue Yuantian , Wang Yudie , Yan Gaoshan , Zhang Hongtian , Wei Chun
Published: July 2024

In this paper, the coupling relationship between energy sources is used to carry out analysis and establish the capacity allocation and optimization model of the integrated energy system. Then a two-layer optimization algorithm is used to establish a linear programming model, which is simulated and analyzed according to the data of a certain region, and solved by CPLEX. The simulation results show that the multi-energy complementary has a good economy and can improve the cleanliness compared with the traditional energy system, which well proves the effectiveness of the proposed capacity optimization model and operation strategy of the integrated energy system.
Ambient Signals based Load Modeling with Two Three-phase Induction Motors
Authors: Han Shenghua , Zhang Xinran , Huang Wanjun , Ling Zihan , Ling Xiaobo , Ye Zheng
Published: July 2024

The traditional electric power system simulation and calculation are based on the simple load model including one motor and one static load. On the one hand, the power system load is getting more and more complex. On the other hand, it’s proved that two kinds of three-phase induction motors will show a little difference. As a result, in this paper, a new model load with two three-phase induction motors is proposed. Besides, the dynamic of the power system load is taken into account. The torque of those two three-phase motors will show different characteristics, that one is constant and the other is variable. Formerly, the dynamic of the load is regarded as the result of an induction motor. However, the single-phase motor and electronic load both lead to the complexity of the load. To get a more accurate calculation, we need a more proper load model. One of the ways to improve the load model is to pay more attention to the ingredients ignored. The single-phase motor and power electronic load make a great difference. Besides, it’s proved that the composited load model with two three-phase motors will be better in the calculation.
Passive Radiative Cooling Materials and Their Applications
Authors: Jia Rongrong , Gao Baohai , He Mingjian , Ren Yatao , Qi Hong
Published: July 2024

Passive radiative cooling naturally lowers the temperature of a cooler by reflecting sunlight and emitting heat into the frigid expanse of universe. While certain natural and synthetic substances may exhibit distinct radiative properties, their radiative efficiency remains minimal. As a result of the notable advancements in micro-nano technology, scientists have created several novel substances that exhibit minimal absorption within the intense solar spectrum (0.3-2.5 μm) but possess elevated emissivity in alternative wavelengths, ideally falling in the atmospheric window spectrum (8-13 μm). The basics of radiative cooling mechanisms are presented in this review, along with an overview of the progress made in radiative materials and their various applications. In upcoming times, this technology of passive radiative cooling, which consumes no energy and produces no greenhouse gases, will become a prominent approach for cooling purposes.
State-of-Charge Estimation of Reconfigurable Supercapacitor
Authors: Li Boyu , Ma Yueyue , Zhu Ren , Li Heng
Published: July 2024

A large body of research has been done on state-of-charge (SOC) estimate of supercapacitors in the literature; most of the works have been on SOC estimation of individual supercapacitor units. Nonetheless, supercapacitors are usually linked to balancing circuits in real-world applications in order to remove inter-cell imbalances. The cells’ system dynamics shift to a new mode when the balancing circuit is turned on, making the SOC calculation techniques that are currently in use inappropriate. Our proposal in this research is a Kalman filtering-based reconfigurable supercapacitor balancing system SOC estimate method. By fusing a reconfigurable balancing circuit with the equivalent circuit model of supercapacitors, we create a linear switching systems model. The switching system’s discrete-time form is shown, and its observability is examined. With filter gains dynamically modified according to the system mode, a switching Kalman filter is intended to estimate the SOC of the switched system. The accuracy of SOC estimation is greatly improved by the suggested method when supercapacitors are in the balancing mode, as confirmed by the simulation results.
Energy Management Considering both Efficiency Optimization and Lifetime Balance of Multi-stack FCS
Authors: Lv Xin , Shen Jiabin , Guo Xiaoyu , Li Ce , Zhou Honglei , Dong Zhen
Published: July 2024

With the increase of energy transformation and environmental protection awarenesses, fuel cells, as a clean and efficient energy conversion technology, have been widely adopted in transportation and stationary power supply applications. A single fuel cell has a limited power capability. On the other hand, the multiple fuel cells are combined into a multi-stack fuel cell system (MFCS), which provides a high power output and modular design. However, the energy management of such multi-stack systems faces challenges such as uneven power distribution, inconsistent stack life, and low overall efficiency. Current multi-stack fuel cell control systems often optimize single objectives, either efficiency or lifetime balance produce the optimized energy management strategy. This may not suffice for the overall system benefit. For example, if only efficiency is optimized by energy management, the failure to consider lifetime balance may result in uneven life degradation for each fuel cell, and vice versa. To address the above issues, this paper proposes an energy management strategy for multi-stack fuel cell systems that considers dual objectives, which can simultaneously ensure the optimal co-optimization of the output efficiency and stack life for each stack, thereby improving the overall operating efficiency and lifetime of the system. The effectiveness and practicality of the proposed energy management control strategy were verified on a 60kW dual-stack PEMFC fixed power generation system developed by SeeEx.
Analysis of Resonance Mechanism of AC Submarine Cable Delivery System for Offshore Wind Power
Authors: Tian Shuxin , Zhou Yu , Liu Lujie , Zhang Yanjiu , Zhao Haoxing
Published: July 2024

Several resonant overvoltage accidents caused by machine-grid interaction in offshore wind power generation systems have led to significant economic losses over the years. To solve this problem, based on the equivalent distributed parameter circuit model of AC submarine cable delivery system, a method combining impedance simulation-time domain simulation and spectrum analysis is proposed to reveal the mechanism of resonant overvoltage and its influencing factors. First of all, considering the phase locked loop (PLL) model and the cable distribution parameter model, an impedance model of AC submarine cable delivery system for offshore wind power is established, which takes into account the dynamic characteristics of PLL and current loop, and provides a model basis for the theoretical analysis. Then, equations for current and frequency at the point of common coupling (PCC) are derived to analyze the mechanism of resonant overvoltage generation and the influence of submarine cable length and power grid strength on resonance. Finally, PSCAD is used to verify the resonance mechanism of AC submarine cable delivery system and its influencing factors.
Analysis of DC Bias in Magnetic Controlled Shunt Reactor and Its Influence on Interturn Protection
Authors: Guo Xiao , Xing Wu , Wang Zhe , Zhu Yucong
Published: July 2024

Magnetic controlled shunt reactor is widely used in new energy transmission, and its special operation characteristics provide dynamic reactive power compensation for the power system, while the reactive power capacity can be continuously adjusted, solving the problem that conventional fixed reactance cannot be applied to reactive power demand fluctuations. This paper briefly introduces the structure and working principle of a magnetic controlled shunt reactor, analyzes the relationship between core magnetic saturation and control current in a magnetic controlled reactor under different DC bias conditions, and the reliability of interturn protection under different working conditions is studied and a feasible scheme is proposed, provides a certain reference for the design and operation and maintenance of magnetic controlled shunt reactor.
Research and Application of New Anti-Condensation System of High-Voltage Switchgear
Authors: Wang Jiayi , Kou Jianqiang , Xia Yankun , Zhou Dianbo , You Mingfu
Published: July 2024

The drastic fluctuations in temperature and humidity in the switchgear environment can lead to condensation, posing the threat to the safe and dependable operation of power equipment. In response to the limitations of current anti-condensation measures, a new anti-condensation system for high-voltage switchgear is proposed. Firstly, this research provides an overview of the cause of condensation and the present situation of relevant prevention technologies. Secondly, a new anti-condensation system for high-voltage switchgear is presented. Drawing upon existing anti-condensation technology, this system effectively addresses prevalent issues such as high air humidity and facile condensation in high-voltage switchgear. Electric field simulation calculations, conducted using COMSOL simulation software, demonstrate that the system does not compromise the normal operation of the switchgear. Finally, practical applications show that the robust operational stability of the system. It consistently achieves precise heat dissipation and dehumidification in high-voltage switchgear, which has high application value.
Passive Equilibrium Circuit for Lithium-Ion Battery State of Charge Balance
Authors: Xie Peng , Chen Rongxing , Xu Wenqiang , Guo Zhiyang
Published: July 2024

Lithium-ion batteries serve as pivotal energy storage solutions in electric vehicles and portable electronics. Precise State of Charge (SOC) estimation is crucial for optimizing battery performance and ensuring longevity. This paper introduces an innovative approach utilizing passive equilibrium circuits for enhanced SOC estimation. The passive balancing circuits actively equalize voltage levels among individual battery cells during both charging and discharging, thereby improving SOC estimation accuracy. The proposed method is implemented and simulated using Matlab Simulink, demonstrating superior performance compared to traditional methods. Simulation results reveal the effectiveness of the passive equilibrium circuit in diverse operating conditions, offering a promising solution for accurate SOC estimation. This research contributes to the advancement of battery management systems, with potential applications in renewable energy storage.
Experimental study on the influence of different sampling methods on the stress-strain and strength characteristics of weathered and water rich sandstone
Authors: Yang Chaoshuai , Lei Shengyou , Yue Xijun , Zou Chong
Published: July 2024

In order to explore the physical and mechanical properties of layered weathered sandstone in a water rich environment, the authors obtained layered sandstone from the tunnel excavation section. Firstly, the physical properties and chemical composition were tested, and then uniaxial tests were conducted on sandstone, in which the loading direction was divided into perpendicular to the specimen bedding, parallel to the specimen bedding, and at a 45 ° angle to the specimen bedding. The uniaxial test results show that the stress-strain curve of sandstone is strain softening type. The uniaxial compressive strength of sandstone is between 2.18 MPa and 28.123 MPa, the residual strength is between 0.122 MPa and 24.284 MPa, the elastic modulus is between 5.843 MPa and 49.45 MPa, the Poisson’s ratio is between 0.303 and 0.484, and the softening coefficient of rock is between 0.15 and 0.20. The uniaxial compressive strength of sandstone samples subjected to blasting disturbance is 38% of that without blasting disturbance, and the elastic modulus is 30% of that without blasting disturbance. The axial and radial strains of sandstone samples significantly increased after blasting disturbance. Blasting significantly reduces the uniaxial compressive strength and elastic modulus of the sample. The uniaxial strength of sandstone decreases exponentially with increasing water content.
Preparation and application of waste cigarette butts-derived mulch film with excellent mechanical properties and optical transparency
Authors: Liu Xianjie , Huang Sijun , Li Genrong , Zhang Qiuquan , Zhang Haitao , Yang Youyu , He Fengjie , Sun Donghong , Ma Zhipan , Huang Jufen
Published: July 2024

The small waste cigarette butts every year worldwide added up is a significant threat to the environment. The main component of cigarette butts is cellulose acetate, which is an excellent film-forming material. Here, a one-step phase transition method was employed to successfully convert waste cigarette butts into a transparent film. This film (160×18×0.5 mm) derived from waste cigarette butts (CB) has high mechanical strength (fracture stress 23.5 MPa, Young’s modulus 13.1 MPa), good thermal stability, and excellent optical transmittance (91.8%), and low haze (40.3%). Its properties rival those of traditional low-density polyethylene (PE) film. Meanwhile, the CB film displayed fascinating bending-ability and folding resistance. The cigarette butt-derived film with low cost and excellent properties exhibits a promising application as agricultural mulch and provides recycle solution for waste cigarette butts.
The research of vibration localization under strong disturbances using modal analysis methods
Authors: Huang Chunwen , Ji Gang
Published: July 2024

Vibration localization is a typical feature of aperiodic structures. This work investigates the vibration localization of framed cylindrical shells with a high disturbance degree. First, the spring oscillator system is considered an example to reveal the general law governing how high disturbance degree influences the vibration transmission in a structure. Then the strong localization coefficient is calculated using the modal analysis method. Finally, the conclusions of the one-dimensional systems are applied to the two-dimensional structures based on the passband approximation equivalent method to derive the strong localization coefficient of the aperiodic ring-ribbed cylindrical shell. This study realizes quantitative calculation of the vibration localization coefficient under high disturbance degree. The results of this work provide theoretical support for reducing the vibration transmission performance of a structure by increasing the degree of disturbance.
A Current-Mode bandgap reference with robust start-up behaviour
Authors: Chen Bingjie , Liu Xue , Wang Xin’an
Published: July 2024

Bandgap reference with robust start-up behavior has an important role in analog circuits. In this paper, conventional current-mode bandgap reference (CMBGR) structures are investigated, along with the problem of conventional structures having multiple operating points during start-up. A CMBGR structure that can eliminate all the operating points by a simple start-up circuit is proposed. The CMBGR proposed in this paper utilizes the 180 nm technology and achieves a nominal temperature coefficient of 16.05 ppm/°C. The circuit consumes a current of 6 μA and occupies an effective area of 0.046 mm2.
Optimum frequency tracking of the ultrasonic motor based on a three-level constant voltage drive
Authors: Cai Kangwei , Fu Ping
Published: July 2024

Ultrasonic motors are widely used in aerospace, smart cameras, and other applications. For ultrasonic motors to have the highest operating efficiency, the operating frequency of the motor needs to be adjusted in real time so that the motor’s operating frequency tracks the optimum frequency. Since the current research is limited to the optimum frequency tracking under constant velocity, the three-level drive parameters need to be adjusted to stabilize the velocity, which lacks precision and does not consider the frequency tracking under variable velocity. This paper explores an optimum frequency tracking scheme for ultrasonic motors under the three-level constant voltage input drive and proposes a variable step-size optimum frequency tracking scheme. The experimental results show that the optimum frequency of ultrasonic motors in variable velocity motion exists, and the proposed tracking scheme with three-level drive parameters can effectively improve the efficiency of the motor and significantly broaden the application scenario of the optimum frequency of ultrasonic motors.
Analysis of gap distance of ultra high voltage AC transmission lines in areas with altitude above 2000m
Authors: Su Yu , Ma Xiaoxu , Zhou Songsong , Liu Delong , Jiang Ling , Xie Shijun
Published: July 2024

Research on long-wave front discharge characteristics of lines and long gaps of substation equipment in high-altitude areas needs to be conducted in a systematic manner immediately in order to guarantee the safety and economy of high-altitude UHV lines with respect to external insulation. However, at present, the gap discharge test of transmission lines is mainly carried out in areas below 2000m above sea level. The actual test is challenging to conduct in the high altitude region, and the test data is incomplete. To further confirm the validity of extrapolation of existing altitude test data to high altitude areas, this paper conducts theoretical analysis based on the real test data under standard meteorological conditions provided by GB/T 24842 standard. The altitude correction methods in IEC 60071-2: 2018 and IEC 60060-1: 2010, the m-coefficient method and g-parameter method, are used to correct the lightning impulse, power frequency, and standard switching impulse of AC transmission line gaps. The discharge voltage in areas below 5000m above 2000m is obtained, and several significant discharge characteristic parameters are obtained. Based on the 50% discharge voltage requirements of various voltage types of 1000kV transmission lines, combined with the discharge voltage curves at multiple altitudes, the minimum air gap distance of transmission lines at the altitude of 2000m-5000m is obtained. The comparative analysis of the correction results of the two methods provides a way of thinking for the next step to carry out the true test of UHV AC transmission line gap discharge in higher elevation regions.
Microgrid energy management strategy based on LSTM-DDQN
Authors: Xin Peiqi , Wang Hongtao , Wang Haobo , Xu Changmeng
Published: July 2024

This paper introduces a novel algorithm, LSTM-DDQN, designed to address the stochastic economic dispatch problem in microgrids. The inherent variability and randomness of photovoltaic (PV) energy pose challenges for accurate output prediction. Traditional approaches, including physical and statistical methods, often fall short in terms of accuracy. For microgrids with a high proportion of PV generation, we propose a new algorithm that combines Long Short-Term Memory (LSTM) neural networks with the Double Deep Q-Network (DDQN) algorithm. The algorithm leverages the LSTM model to capture the uncertainty of the learning environment and optimizes the Q-value iteration rules in the DDQN algorithm, thereby enhancing the training speed of the neural network. Experimental results demonstrate the algorithm’s remarkable dispatch capabilities in managing the interplay between PV generation, battery capacity, and overall load demand. This algorithm provides robust support for the stable operation of microgrids.
Multi-port DC transformer applied to large-scale DC collection systems
Authors: Teng Shangfu , Fan Linzhen , Chen Qichen , Su Jinguo , Li Tai
Published: July 2024

This paper proposes a multi-port DC transformer for boosting and flexible interconnection in large-scale DC collection systems. It can transmit power and adjust port current, while also having a relatively simple control strategy. The engineering practicality of the proposed DC transformer can be well verified through the simulation of a 4 GW DC collection system. In this application scenario, the proposed DC transformer can operate stably and safely under both dynamic and steady-state conditions.
A measurement method for magnetic moment and magnetic declination of ferromagnetic samples based on rotating magnetic dipole
Authors: Zhang Shizheng , Chen Tao , Fu Tianyu , Ai Danni , Yang Jian
Published: July 2024

This paper presents a novel measurement method for detecting the magnetic properties of ferromagnetic materials. The proposed method uses a motor to rotate the ferromagnetic sample. At the same time, a triaxial magnetometer reads the magnetic field information, and the motor rotation frequency and the magnetometer sampling rate obtain the rotation angle information. A nonlinear optimization algorithm is applied to calculate the magnetic moment and magnetic declination angle of the sample. The effectiveness of the method is proved by numerical simulation and experimental measurement. Our results indicate that the proposed method offers several advantages, including its ease of deployment, simplicity of operation, high accuracy, and robustness. It provides a feasible solution for laboratory-based magnetic moment measurements and rapidly detecting magnetic moments in industrial settings.
LQR controller design for portable power supply based on flyback converter
Authors: Zou Bing , He Dehui , Liang Jianan
Published: July 2024

The stability of the power repair equipment guarantees the reliability of the repair of electrical equipment. The following problems exist in the power supply of the emergency equipment: the load equipment randomly cuts in the power supply network; load equipment requires fast dynamic performance of the power supply. This challenges the stability of the portable power supply with the Flyback converter as the core. In this paper, an optimal feedback control strategy based on linear quadratic regulator (LQR) theory is proposed to improve the dynamic and steady-state performance of the Flyback converter. First, the state-averaged space model of the Flyback is derived and established. Second, an output voltage feedback integral controller is introduced to eliminate the steady-state error of the output voltage. Next, according to the LQR optimal control theory, the control model of the Flyback converter has been established, and the parameter design of the controller has been carried out by obtaining the optimal feedback gain matrix of the system. Finally, the simulation models are implemented with an output power of 120 W and a switching frequency of 50 kHz. The simulation results prove that the LQR controller provides superior performance than the traditional PI controller.
Design of wireless transmission system for intelligent agricultural greenhouse data acquisition based on modbus communication protocol
Authors: Peng Zhaoxia , Cui Zhiyong , Zhong Dongbo
Published: July 2024

Traditional agricultural greenhouses rely too much on manual labor and have a poor ability to adjust the key factors that affect crop growth, such as temperature, humidity, and illumination, resulting in low production efficiency and unstable product quality. Based on the MODBUS communication protocol, a set of intelligent agricultural greenhouse data acquisition wireless transmission systems is designed in this paper. Intelligent instruments, sensors, wireless transmission equipment, and smart control equipment (PLC) have been introduced in agricultural greenhouses. These sensors and instruments automatically collect data and wirelessly transmit it to the intelligent control system in the control room, which is located a few kilometers away. The intelligent control system processes the data and generates various control instructions which are then transmitted to the executive mechanism in agricultural greenhouses for implementation. We complete automatic adjustment of temperature, humidity, illuminance, and other parameters and operations. The intelligent, large-scale, and unmanned agricultural greenhouses are realized. It greatly improves the production efficiency and product quality of crops.
Fault diagnosis of the traction main circuit based on product-based neural network
Authors: Huang Weijia , Zhu Qinyue
Published: July 2024

The traction main circuit serves not only to supply power to the EMUs train set but also plays a crucial role in the initiation, speed regulation, and braking of the train. Therefore, diagnosing the operational status of the traction main circuit is of paramount importance. This paper initiates the modeling of the traction main circuit for the CRH2 EMUs train set, followed by an analysis of the primary components’ faults within the traction main circuit. Voltage and current signals from the transformer’s primary side, traction winding, as well as the stator current and speed signals of the traction motor, are collected. Fault characteristics are then extracted using FFT and wavelet analysis methods. Subsequently, employing the Product-based Neural Network (PNN), the transformer, converter, and motor are subjected to fault diagnosis. Experimental results validate the high accuracy of the proposed fault diagnosis method presented in this paper.
Research on simulation accuracy of equivalent aggregate electromagnetic model optimization for large renewable energy stations
Authors: Wu Xiaorong , Cao Bin , Xing Yue , Shen Zhuoxuan
Published: July 2024

The traditional power grid is rapidly transforming into a new power system with high penetration of new energy. Simulation modeling plays an important role in supporting the cognition and research of the new power system. A high proportion of renewable energy is connected to the grid through power electronic components, which puts forward a higher demand for research on the accuracy and stability of power grid simulation modeling. Renewable energy plants usually have a large number of single units, and equivalent aggregation modeling is the usual way to simplify the modeling of renewable energy plants. However, the transmission line power multiplier equivalent module inevitably introduces series impedance into the network, resulting in errors between simulation and actual engineering. Therefore, the study of lossless multiplier elements based on Modified Nodal Analysis (MNA) can improve the simulation accuracy, and it is verified with the simulation results of detailed models in actual scenarios, proving that MNA lossless multiplier elements can optimize the accuracy and stability of equivalent aggregation modeling of large-scale multi-unit renewable energy stations.
Research on PCB layout optimization of vehicle controller based on electrothermal hybrid simulation
Authors: Zhang Yanfei , Hou Daizheng , Zhou Yafu
Published: July 2024

With the rapid development of the electronic industry, electronic equipment is more and more widely used in automobiles. The integration of electronic components on the Printed Circuit board (PCB) is getting higher and higher, the size is getting smaller and smaller, and the power is getting larger and larger, which leads to a sharp increase in the heat flow density of the whole PCB. The surface temperature of the chip is too high when it is working, which leads to a series of thermal failure problems. In order to improve the thermal characteristics between PCB and electronic components and improve the heat dissipation capability and reliability of PCB, this paper designed a vehicle controller PCB. PowerDC was used to conduct an electrothermal hybrid simulation analysis, and the temperature distribution of the whole board was obtained. Meanwhile, the structural layout of the PCB was optimized by increasing the heat dissipation hole, floor copper foil, and wiring width. Thus, the temperature of PCB and electronic components is reduced, which provides a vital reference for the thermal design of PCB.