Multi-Equipment Detection Method for Distribution Lines Based on Improved YOLOx-s

The YOLOx-s network does not sufficiently meet the accuracy demand of equipment detection in the autonomous inspection of distribution lines by Unmanned Aerial Vehicle(UAV)due to the complex background of distribution lines,variable morphology of equipment,and large differences in equipment sizes.Therefore,aiming at the difficult detection of power equipment in UAV inspection images,we propose a multi-equipment detection method for inspection of distribution lines based on the YOLOx-s.Based on the YOLOx-s network,we make the following improvements:1)The Receptive Field Block(RFB)module is added after the shallow feature layer of the backbone network to expand the receptive field of the network.2)The Coordinate Attention(CA)module is added to obtain the spatial direction information of the targets and improve the accuracy of target localization.3)After the first fusion of features in the Path Aggregation Network(PANet),the Adaptively Spatial Feature Fusion(ASFF)module is added to achieve efficient re-fusion of multi-scale deep and shallow feature maps by assigning adaptive weight parameters to features at different scales.4)The loss function Binary Cross Entropy(BCE)Loss in YOLOx-s is replaced by Focal Loss to alleviate the difficulty of network convergence caused by the imbalance between positive and negative samples of small-sized targets.The experiments take a private dataset consisting of four types of power equipment:Transformers,Isolators,Drop Fuses,and Lightning Arrestors.On average,the mean Average Precision(mAP)of the proposed method can reach 93.64%,an increase of 3.27%.The experimental results show that the proposed method can better identify multiple types of power equipment of different scales at the same time,which helps to improve the intelligence of UAV autonomous inspection in distribution lines.

Prospects of key technologies of integrated energy systems for rural electrification in China

Owing to increasing environmental concerns and resource scarcity, integrated energy system shave become widely used in communities. Rural energy systems, as one of the important links of the energy network in China, suffer from low energy efficiency and weak infrastructure. Therefore, it is particularly important to increase the proportion of electricity consumption and build an integrated energy system for rural electrification in China(IESREIC) with a rural distribution network as the core, in line with national conditions. In this study, by analyzing the Chinese regional differences and natural resource endowments, the development characteristics of the IESREIC are summarized. Then, according to the existing rural energy problems, key technologies are proposed for the IESREIC, such as those for planning and operation, value sharing, infrastructure, and a management and control platform. Finally, IESREIC demonstration projects and business models are introduced for agricultural production, rural industrial systems, and rural life. The purpose is to propose research concepts for the IESREIC, provide suggestions for the development of rural energy, and provide a reference for the construction of rural energy systems in countries with characteristics similar to those of China.

Preliminary Study of Thermal Treatment of Coke Wastewater Sludge Using Plasma Torch

Thermal plasma was applied for the treatment of coke wastewater sludge derived from the steel industry in order to investigate the feasibility of the safe treatment and energy recovery of the sludge. A 30 kW plasma torch system was applied to study the vitrification and gas production of coke wastewater sludge. Toxicity leaching results indicated that the sludge treated via the thermal plasma process converted into a vitrified slag which resisted the leaching of heavy metals. CO2 was utilized as working gas to study the production and heat energy of the syngas. The heating value of the gas products by thermal plasma achieved 8.43 k J/L, indicating the further utilization of the gas products. Considering the utilization of the syngas and recovery heat from the gas products, the estimated treatment cost of coke wastewater sludge via plasma torch was about 0.98 CNY/kg sludge in the experiment. By preliminary economic analysis, the dehydration cost takes an important part of the total sludge treatment cost. The treatment cost of the coke wastewater sludge with 50 wt.% moisture was calculated to be about 1.45 CNY/kg sludge dry basis. The treatment cost of the coke wastewater sludge could be effectively controlled by decreasing the water content of the sludge. These findings suggest that an economic dewatering pretreatment method could be combined to cut the total treatment cost in an actual treatment process.

Dielectric barrier discharge-based defect engineering method to assist flash sintering

Oxygen vacancy OV plays an important role in a flash sintering (FS) process. In defect engineering, the methods of creating oxygen vacancy defects include doping, heating, and etching, and all of them often have complex processes or equipment. In this study, we used dielectric barrier discharge (DBD) as a new defect engineering technology to increase oxygen vacancy concentrations of green billets with different ceramics (ZnO, TiO_(2), and 3 mol% yttria-stabilized zirconia (3YSZ)). With an alternating current (AC) power supply of 10 kHz, low-temperature plasma was generated, and a specimen could be treated in different atmospheres. The effect of the DBD treatment was influenced by atmosphere, treatment time, and voltage amplitude of the power supply. After the DBD treatment, the oxygen vacancy defect concentration in ZnO samples increased significantly, and a resistance test showed that conductivity of the samples increased by 2–3 orders of magnitude. Moreover, the onset electric field (E) of ZnO FS decreased from 5.17 to 0.86 kV/cm at room temperature (RT);while in the whole FS, the max power dissipation decreased from 563.17 to 27.94 W. The defect concentration and conductivity of the green billets for TiO_(2) and 3YSZ were also changed by the DBD, and then the FS process was modified. It is a new technology to treat the green billet of ceramics in very short time, applicable to other ceramics, and beneficial to regulate the FS process.

Emission Behaviors of Submicron Particles(PM_(1))Generated by the Combustion of Sesame Stalk after Combined Water Washing and Carbonization Pretreatment

Pretreatment before biomass combustion is significant for its efficient utilization and that combined water washing and carbonization can be efficient.An agricultural processing residues sesame stalk was selected and carried out two pretreatments separately,i.e.,water washing-torrefaction(W-T)and torrefaction-water washing(T-W),to explore the effect on the fuel properties,combustion characteristics and particulate matter(PM)emission.The obtained biochar was also combusted under air and oxy50(CO_(2):O_(2)=50:50)conditions for the sake of investigating the effect of pretreatment and combustion atmosphere.The results indicate that,W-T and T-W both not only have great effect on the improvement of fuel properties but also reduce the content of water-soluble elements like K,Cl,etc.Due to the difference in hydrophobicity,the biochar obtained by W-T have the optimal fuel properties.At the same time,the pretreatment also hinder the combustion in a certain extent in which the comprehensive combustion characteristics(SN)show a downward trend.Furthermore,both two pretreatments have obvious benefit on the reduction of PM_(1)emission and W-T have the best effect related to the higher removal efficiency of inorganic elements(especially K+Na+Cl+S).Under oxy50 condition,the oxygen concentration and combustion temperature is higher,improving the sulfation of K and vaporization of Ca,P and Mg which result in weakening in the pretreatment reduction effect on PM_(1)emission.

Decomposition analysis of CO_(2) emissions of electricity and carbon-reduction policy implication: a study of a province in China based on the logarithmic mean Divisia index method

As the proportion of electricity in final energy consumption gradually increases,CO_(2) emissions reduction actions in the power system will become the key to achieving China’s carbon-peak and carbon-neutrality goals.It is essential to analyse and quantify the driving forces of CO_(2) emissions from electricity generation in the fossil-rich area in China.This paper aims to identify the characteristics of CO_(2) emissions generated by electricity and provide a basis for formulating CO_(2)-reduction policies in power systems.First,we analyse the current state of CO_(2) emissions from electricity generation in Anhui Province that was dominated by fossil energy during the period 2010-19.Then,we apply the logarithmic mean Divisia index method to find the nature of the factors influencing the changes in CO_(2) emissions.Finally,we analyse the CO_(2)-reduction measures of each side of the source-network-load-storage of the power system in Anhui through a power-system carbon-reduction path analysis model proposed in this study and provide policy suggestions.The results showed the following.(i)CO_(2) emissions in Anhui Province continued to increase from 2010 to 2019 and the trend in the growth rate of CO_(2) emissions presented approximately a u-shaped curve.(ii)Economic activity has always been the dominant factor driving the growth of electricity CO_(2) emis-sions.The increase in the proportion of renewable energy in power generation,the improvement in thermal power-conversion efficiency and the decrease in the intensity of power consumption are the three major driving factors for the reduction in CO_(2) emissions from power generation in Anhui.(iii)The CO_(2)-reduction measures of the power system are provided in each link of the source-network-load-storage,such as developing the photovoltaic industry and building energy storage,upgrading and transforming coal-fired power stations,redu-cing the loss rate of transmission lines on the grid side and improving the efficiency of the utilization of electricity on the user side.

Mid-short-term risk assessment of power systems considering impact of external environment

Ice flashover,lightning flashover and bird damage are the main reasons that cause transmission facility failure.The impact of these environmental factors on the operational risk levels of power systems should be taken into account in power system maintenance scheduling and operation planning.This paper studies the midshort-term risk assessment methodology considering the impact of the external environment.The relationship model between natural disasters and transmission lines is presented.The conditional outage rate model and the sampling technique are then proposed considering the correlated outage of multiple transmission lines when a disaster happens.The framework of the mid-short-term risk assessment model is outlined.A test case of Jiangxi provincial power grid validates the proposed model.The results show that the model can quantify the impact of disasters on the forced outage rate of transmission component and their outage correlation,and thus effectively revealing the mid-short-term risk of power systems.The model can facilitate a more strategic decision-making on maintenance scheduling and operation planning of power systems.

ZnO@Mo-CNT-MnO_(2)纳米阵列用于构筑超高倍率性能的柔性非对称超级电容器

MnO_(2)作为超级电容器电极材料具有理论比电容高、成本低、环境友好等优点,但其低导电性和低利用率阻碍了其潜在应用.本研究首先在柔性碳布上电化学生长ZnO纳米棒阵列作为电极衬底,然后通过阳极电沉积法在ZnO纳米棒阵列表面外延生长了Mo和碳纳米管(CNTs)共掺杂的MnO_(2)薄膜,可控构筑了有效、高导电性的MnO_(2)纳米阵列电极(定义为ZnO@Mo-CNT-MnO_(2)NA).柔性ZnO@Mo-CNTMnO_(2)NA电极在100 A g^(-1)的大电流充放电密度下比电容可达237.5 F g^(-1),10,000次循环后电容保留率高达86%.采用ZnO@Mo-CNTMnO_(2)NA电极组装成水系非对称超级电容器,弯曲状态下在132.35 mW cm^(-3)(5mA cm^(-2))高功率密度下获得了1.13 mW h cm^(-3)的高能量密度,5mA cm^(-2)充放电倍率下循环7600次后电容保留率高达88%.本研究构筑的MnO_(2)基纳米阵列电极结构可提高其电导率和利用率,为柔性金属氧化物超级电容器电极的设计与制备提供新途径.

Increased Oxygen Evolution Activity in pH-Universal Electrocatalyst: Urea-Modified NiFeCoCN Medium-Entropy Alloy

The kinetic process of a slow oxygen evolution reaction (OER) always constrains the efficiency of overall water electrolysis for H2 production.In particular,nonprecious metal electrodes for the OER have difficulty in possessing excellent electrocatalytic activity and stability in pH-universal media simultaneously.In this work,urea is first used as a pore-forming agent and active C/N source to fabricate a nanoporous NiFeCoCN medium-entropy alloy (MEA) by high-temperature sintering based on the nanoscale Kirkendall effect.The NiFeCoCN MEA achieves an overpotential of 432 mV at a current density of 10 mA·cm^(-2) and a lower Tafel slope of 52.4 mV·dec^(-1) compared to the IrO_(2)/Ti electrode (58.6 mV·dec^(-1)) in a 0.5 mol/L H_(2)SO_(4) solution.In a 1 mol/L KOH solution,the NiFeCoCN MEA obtains an overpotential of 175 mV for 10 mA·cm^(-2) and a Tafel slope of 40.8 mV·dec^(-1),which is better than IrO_(2)/Ni foam.This work proves a novel strategy to design and prepare nanoporous MEA materials with desirable C/N species,which provides promising prospects for the industrial production of H2 energy.

Intelligent Breakage Assessment of Composite Insulators on Overhead Transmission Lines by Ellipse Detection Based on IRHT

With the development of unmanned aerial vehicle(UAV)technology,visible images are playing an important role in the maintenance of power systems.To achieve the shed breakage evaluation of composite insulators by UAV visible images,an intelligent fault assessment method is proposed.First,the composite insulators in visible light images are identified by Faster-RCNN.After image preprocessing,the image is enhanced and the noise is removed.Then,a canny operator is used to extract the edge of the sheds.An Improved Randomized Hough Transform(IRHT)is used to detect the ellipses in the edge image.The parameters of the detected ellipse,length of major axes and minor axes,center coordinates and deflection angle of major axes,are used to realize the segmentation of the composite insulator.Finally,the number of pixel points in the ellipse and the distance between the points and the ellipse boundary are used to judge whether there are breakage or cracks on the sheds.The area ratio of the breakage to the whole shed is calculated based on the number of pixel points inside the broken area.This method can be realized without a large amount of training dataset of the specific fault type and provides a technical basis for the online fault assessment of a composite insulator on overhead transmission lines.

Grounding fault location method of overhead line based on dual-axis magnetic field trajectory

To address the challenges in fault location in distribution networks,the distribution of magnetic field under overhead line and its relationship with three-phase currents are explored in this paper.At the same time,considering the influ-ence of sensor installation position,line sag and galloping on magnetic field,a grounding fault location method of an overhead line based on dual-axis magnetic field trajectory is proposed.The analytical expressions of the magnetic field on the x-axis and y-axis under the overhead line are obtained by least squares fitting.The Lissajous figure synthe-sized by dual-axis is then compared with the general equation of an ellipse,and the characteristic quantity expression characterizing the magnetic field trajectory structure is obtained.Finally,a fault location criterion is constructed using the difference of the characteristic quantities of the ellipses synthesized by x-axis and y-axis magnetic fields upstream and downstream of the fault point,i.e.,the difference of the length of the major axis and the minor axis,and the sign for the ratio of the cosine value of the inclination angle.Compared with other location methods based on electrical quantity,the principle of this method is simpler and it can locate faults more quickly and accurately.A large number of simulation results show that the proposed method is suitable for different types of fault conditions.

Flash sintering of high-purity alumina at room temperature

For the first time,the flash sintering(FS)of high-purity alumina at room temperature,which was previously considered unachievable due to its low electrical conductivity,was conducted herein.The electrical arc originating from surface flashover was harnessed to induce FS at room temperature and low air pressure.The successful FS of high-purity alumina was realized at 60 kPa under the arc constraint,resulting in a notable relative density of the alumina sample of 98.7%.The electric–thermal coupling between the arc and high-purity alumina sample during the arc-induced FS process was analyzed via the finite element simulation method.The results revealed the thermal and electrical effects of the arc on the sample,which ultimately enhance the electrical conductivity of the alumina sample.The formation of a conductive channel on the sample surface,a result of increased electrical conductivity,was the pivotal factor in achieving FS in high-purity alumina at room temperature.The arc constraint technique can be applied to numerous materials,such as ionic conductors,semiconductors,and even insulators,under room-temperature and low-air-pressure conditions.

Polar Influence of the Organic Modifiers on the Structure of Montmorillonite in Epoxy Nanocomposites

The epoxy nanocomposites with similar amines （CH3（CH2）17NH2 and CH3（CH2）17N（CH3）301） treated montmorillonite clays have been investigated by wide-angle X-ray scattering, transmission electron microscopy （TEM）, differential scanning calorimetry （DSC） and thermal gravimetric analysis （TGA）. Different nanocomposite structures, intercalation and exfoliation were formed by the reaction of octadecyltrimethylammonium chloride-exchanged and octadecylamine-exchanged clays with epoxy resin and phenalkamine as the curing agent, respectively. Results showed that the exfoliated nanocomposite can be obtained when octadecylamine with the lower polarity was used as a modifier. However, the intercalated nanocomposite can be obtained when octadecyltrimethylammonium chloride with higher polarity was used as a modifier.

Gas-discharge induced flash sintering of YSZ ceramics at room temperature

This is the first study to conduct the flash sintering of 3 mol%yttria-stabilized zirconia(3YSZ)ceramics at room temperature(25℃)under a strong electric field,larger than 1 kV/cm.At the standard atmospheric pressure(101 kPa),the probability of successful sintering is approximately half of that at low atmospheric pressure,lower than 80 kPa.The success of the proposed flash sintering process was determined based on the high electric arc performance at different atmospheric pressures ranging from 20 to 100 kPa.The 3YSZ samples achieved a maximum relative density of 99.5%with a grain size of~200 nm.The results showed that as the atmospheric pressure decreases,the onset electric field of flash sintering decreases,corresponding to the empirical formula of the flashover voltage.Moreover,flash sintering was found to be triggered by the surface flashover of ceramic samples,and the electric arc on the sample surfaces floated upward before complete flash sintering at overly high pressures,resulting in the failure of flash sintering.This study reveals a new method for the facile preparation of flash-sintered ceramics at room temperature,which will promote the application of flash sintering in the ceramic industry.

High‐performance ZnO varistor ceramics prepared by arc‐induced flash sintering with low energy consumption at room temperature

The development of ultra‐high voltage transmission lines requires a ZnO arrester with excellent electrical response and high voltage gradient.Compared with conventional preparation methods,flash sintering allows fast production of novel high‐performance ZnO varistor ceramics with low energy consumption and controlled grain growth.Herein,ZnO varistor ceramics were prepared using the flash sintering method at an air pressure of 21 kPa for 60 s at 25℃.The results showed that the flash‐sintered samples had fine grains and reduced loss of volatile elements.Moreover,the voltage gradient,leakage current density,and non‐linear coefficient of the flash‐sintered varistor ceramics were significantly improved compared with those of conventionally sintered samples.Owing to the short preparation time and absence of a heating process,the energy consumption of the proposed flash sintering method was significantly reduced to 10%of that by conventional sintering.The proposed method is a promising approach for the preparation of ZnO arresters with excellent electrical properties and serves as an effective method that realises energy saving and emission reduction.

A versatile defect engineering strategy for room-temperature flash sintering

In this study,we reported that flash sintering(FS)could be efficiently triggered at room temperature(25℃)by manipulating the oxygen concentration within ZnO powders via a versatile defect engineering strategy,fully demonstrating a promising method for the repaid prototyping of ceramics.With a low concentration of oxygen defects,FS was only activated at a high onset electric field of~2.7 kV/cm,while arcs appearing on the surfaces of samples.Strikingly,the onset electric field was decreased to<0.51 kV/cm for the activation of FS initiated,which was associated with increased oxygen concentrations coupled with increased electrical conductivity.Thereby,a general room-temperature FS strategy by introducing intrinsic structural defect is suggested for a broad range of ceramics that are prone to form high concentration of point defects.