最新刊期
卷 60 ， 期 2 ， 2024
- 摘要：The difficulty of insulation structure design of high-voltage DC apparatus increases significantly with the increase of voltage level, and it cannot be simply handled by increasing the size of AC insulation part. Otherwise, it will not only increase the size and cost of the product, but also accumulate a large amount of charge on the surface of the insulation part with temperature gradient during operation, causing severe distortion of the electric field distribution. In recent years, numerous studies have attempted to improve the electric field distribution of DC insulation part by adjusting the quality of insulation part or applying surface coatings. Although some research results have been obtained, yet they cannot be used in product design. It is emphasized in this paper that the opinion of improving charge accumulation and electric field distribution by adjusting the shape of insulation part, new design of DC insulation part with small structural dimensions and good electric field distribution called ‘disc/cone’ is proposed. Its structure and electric field are optimized and calculated. The design of the support part in the busbar of basic busbar unit of GIS is analyzed and verified. In addition, the corresponding prevention measures on the design idea of prevention of metal particle of insulation inside the product, with prevention rather than the control, is proposed. The research scheme of permissible value of various filed strength which must be used in the design of HVDC product is proposed. It is proposed in this paper that conical disc/cone spacer insulating parts is also applicable the selection and application of other EHV/UHV DC gas insulated apparatus关键词：UHV DC insulation structure;disc/cone insulator;surface charge and electric field optimization23|152|1更新时间：2025-04-26
- 摘要：DC circuit breaker is the core protection equipment of DC traction power supply system of rail transit and the guarantee of safe operation of DC power supply system, it is therefore very important to ensure its stable operation. As for the mechanical structure characteristics of DC traction circuit breaker in this paper, the mechanical fault simulation experiment of circuit breaker is performed. The current and vibration signals of the opening and closing coils are selected as the monitoring physical quantities to study its mechanical fault mechanism and feature extraction method. The hardware device of signal acquisition is developed, and the experimental platform of mechanical fault simulation of DC circuit breaker is set up to simulate six kinds of common mechanical faults. The coil current and vibration signals under different faults are collected for feature extraction and fault mechanism analysis, which can provide theoretical support for mechanical fault diagnosis of low-voltage DC circuit breaker.关键词：DC circuit breaker;mechanical failure;current signal;vibration signal;feature extraction10|142|0更新时间：2025-04-26
- 摘要：The very fast transient over-voltage/over-current generated during switching operation of disconnector may result in a significant threat to the reliability of power grid. However, there is a lack of research on the variation characteristics and law of electromagnetic interference in the very fast transient process of the disconnector. In this paper, the transient voltage and current data of opening and closing small capacitive current test of disconnector is taken as the base, the characteristic data of the corresponding macropulse and monopulse waveform is extracted to perform comprehensive statistical analysis of the transient waveform characteristic data by way of probability density function fitting and Kolmogorov-Smirnov (KS) test of the sample cumulative empirical distribution. The results show that the probability density of macropulse waveform duration of opening and closing operation follows generalized extreme value (GEV) and inverse Gaussian distribution respectively. The maximum peak of VFTO and VFTC monopulse is 50 kV and 370 A respectively, the rise time is in the range of nano- and micro- seconds respectively. The monopulse interval time is ms level. The number of monopulse of opening and closing operation shows normal distribution. The research result can provide scientific evidence for the development of strong electromagnetic disturbance standard test source and the formulation of electromagnetic compatibility standard tests at system level.关键词：disconnector;very fast transient;waveform parameters;probability density estimation;statistical analysis12|318|0更新时间：2025-04-26
- 摘要：The mechanical fault diagnosis algorithm of DC circuit breaker is the core part of on-line monitoring system of mechanical status of DC circuit breaker. In this paper, the mechanical fault simulation experiment of DC circuit breaker is performed. The coil current and vibration signals under different faults are collected. After extraction of its feature, the current feature, vibration short-time energy feature and wavelet packet frequency band energy feature are permuted and combined and the fault diagnosis model is constructed by using the support vector machined. In this paper, the principal component analysis (PCA) method and Relief-F algorithm are used for dimensionality reduction of different feature combinations to analyze further the diagnosis effect after dimensionality reduction of feature combinations. Moreover, the K-Fold cross validation algorithm is used to assesses the diagnosis model which is output by the single feature and feature combination training output so to select the diagnosis model with the optimal classification performance.关键词：DC circuit breaker;mechanical fault diagnosis;support vector machine;feature dimension reduction;cross validation11|280|1更新时间：2025-04-26
- 摘要：For studying the discharge development process of air gap defects at the interface of GIS insulators, a void air gap defect model is designed in this paper, and a long-term test platform for GIS air gap defect discharge is set up. Based on the breakdown voltage of the defect model, the AC constant voltages of 90%Ub, 60%Ub, and 30%Ub are applied to the test sample with defects, and the UHF detection system is used to collect the discharge data until breakdown of the sample. The discharge state characteristics are analyzed by extracting the discharge times, amplitude and time interval, finding that there are two stages in the discharge development process of air gap defects of GIS. In the former stage, the discharge amplitude increases gradually, the discharge pulse is gradually sparse and the the discharge development is gradually stable. While, in the latter stage, the discharge amplitude decreases sharply, the discharge pulse is dense and the discharge development is drastic. The k-means clustering algorithm and BP neural network are used to set up the division rule of the partial discharge development stage of the air gap defect. The research shows that such three characteristic parameters as discharge times, amplitude and time interval show a trend of staged monotonicity. The absolute value of the forward difference of the three characteristic parameters can be used to assess the severity of GIS air-gap discharge of GIS. The cluster analysis of the GIS constant voltage test is performed to divide the discharge process into a stable deterioration stage and an accelerated deterioration stage. With the decrease of the applied voltage level, the stable deterioration stage is compressed and the proportion of the accelerated deterioration stage is increased.关键词：GIS insulators;discharge of void defect;constant voltage test method;state division;evaluation10|265|0更新时间：2025-04-26
- 摘要：Based on the lifetime ablation test data of LW30-40.5 SF6 circuit breaker, normalized anomaly index F is adopted in this paper to reflect the remaining electrical life of contact of the circuit breaker, where 0 indicates complete electrical life and 1 indicates exhaustion of electrical life. According to the dynamic resistance-stroke curve of the circuit breaker, the first peak point with a stroke greater than 8 mm and a resistance greater than 500 μΩ on the dynamic resistance-stroke curve is proposed as the dividing point between the contacting stage of main contact of and the contacting stage of arc contact of the circuit breaker. Based on this, five characteristic parameters reflecting the abnormal index F of contact of the circuit breaker are obtained. The Pearson correlation coefficient method is used to analyze the characteristic parameters independently. LSTM neural network is used to set up a regression prediction model on the basis of relationship between the characteristic parameters and the anomaly index F. The mean square error and absolute mean error of the regression prediction of the F index are 0.014 921 and 0.013 053, respectively. The MIV method is used to determine the influence weights of each characteristic parameter on the anomaly index F.关键词：SF6 circuit breaker;electrical life;dynamic resistance;LSTM - MIV neural network;regression prediction9|139|0更新时间：2025-04-26
- 摘要：In this paper, the influence of different ignition positions on the fire of high-voltage switchgear cabinet is studied on the basis of fluid dynamics calculation software, and the fire characteristic parameters of temperature field, dimensionless temperature factor, soot distribution and total heat release rate inside the cabinet are analyzed. The calculation results show that, in case of fire of handcart compartment, the maximum temperature is lower than that of the cable compartment or busbar compartment and, moreover, the dimensionless temperature of top or side wall at different fire positions has obvious difference, which can be used as the diagnosis means for the early fire safety warning. The distributions of soot and total heat release rate also show that, in case of fire in the cable compartment and handcart compartment, the soot can be filled fully in the complete high-voltage switchgear cabinet. While, in case of fire in the busbar compartment, the soot is only filled fully the busbar compartment. In addition, the fire of cable compartment has higher total the released rate and more heat is released due to the ignition of the combustible element of the adjacent handcart compartment. The research result in this paper can not only recognize and understand the development trend of fire spread of high-voltage switchgear cabinet, but also provide technical and theoretical support for the early safety warning of the high-voltage switchgear cabinet.关键词：high-voltage switchgear cabinet;fire;ignition position;fire safety;heat release rate10|196|0更新时间：2025-04-26
- 摘要：Dead tank clean air insulated switchgear is an ideal upgrade solution of environmental-friendly switchgear. Compared to cubic-type switchgear, its insulation performance is better and, however, the problem of high current heating and temperature rise is still prominent. In this paper, the modeling, comparison and calculation of the spring contact finger connection and three-phase busbar of a kind of 40.5 kV dead tank clean air insulated cabinet are performed from the point of view of reducing heating power. The electrical connection model of a kind of V-shaped spring contact finger is set up by using finite element method, and the influence of alternating electromagnetic field on shunting of the parallel contact finger is calculated. The current flow and power loss differences between double and single spring contact fingers are compared. The influence of contact finger material on heating is quantitatively calculated, and a kind of preferred cobalt bronze double spring contact finger electrical connection scheme is confirmed. The influence of skin and proximity effect on the heating power of the three-phase conductor is studied by way of setting up a three-dimensional electromagnetic field model of the three-phase busbar. The alternative aluminum alloy material is compared, and a high conductivity aluminum alloy hollow conductor is confirmed as the preferred design scheme. The differences in AC and DC resistance of the busbar conductors are calculated and compared. The conclusions and modeling as well as simulation methods obtained in this paper have guiding significance for the design of contact finger and conductor of AC high current environmentally friendly electrical products.关键词：spring contact finger;three - phase busbar;alternating electromagnetic field;heating power;simulation analysis13|40|0更新时间：2025-04-26
- 摘要：For achieving the transition of the dielectric medium of gas insulated switchgear cabinet from SF6 to such environmentally friendly gas as dry air, it is an urgent issue to develop an embedded pole for dry air insulated switchgear cabinet with a smart structure and insulation level meeting requirement. In this paper, the electric field distribution of phase-to-phase and phase-to-ground of 40.5 kV SF6 embedded pole which is placed in the air insulated switchgear is analyzed. The result shows that the gas-solid surface electric field near the moving and static end cover as well as insulation rod of the arc interrupter seriously exceeds the standard, which is likely to cause surface flash-over. Based on gas-solid composite insulation theory, the electric field is optimized by such measures as adding grading shield network, improving appearance structure of insulation enclosure and redesigning insulation rod ect. Through simulation analysis, maximum field strength along the surface near the cover of arc interrupter after the optimal design is reduced from 3.4 kV/mm to 2.03 kV/mm, and the maximum field strength along the insulation rod is reduced from 4.1 kV/mm to 1.7 kV/mm. Partial discharge and lightning impulse tests are performed on the embedded poles before and after optimization. The arcing ignition voltage of the partial discharge test is increased from 35 kV to 62 kV, and the peak withstand voltage of lightning impulse test is increased from 145 kV to 218 kV, which proves the feasibility of the optimized scheme and provides a reference for the subsequent development and optimization of similar embedded poles at 40.5 kV and above.关键词：dry air insulation;embedded pole;simulation analysis;electric field along surface;voltage equalizing shielding;structure optimization;partial discharge;lightning impulse28|145|1更新时间：2025-04-26
- 摘要：DC contactor is the key device to achieve the function of breaking, power switching and fault protection. One DC contactor is taken as an example in this paper, a two-dimensional fluid dynamic model for hydrogen arc characteristics simulation of DC contactor is set up. The influence of such factors on external load circuit, contact motion and non-uniform external magnetic field on the arc characteristics of the contactor is comprehensively considered in this model, and the current and voltage variation curve and the temperature field distribution in the case arc breaking period of the encapsulated DC contactor with different thickness of magnetic steel are simulated and researched. The research results show that under the action of non-uniform magnetic field with different thickness of magnetic steel, the arcing time of internal arc of DC contactor at 450 V/400 A and gas filling pressure of 4 atm (1 atm=101 kPa) is different. With the increase of thickness of magnetic steel, the intensity of magnetic field becomes strong, the arcing time becomes short and the arcing time of the magnetic steel with the thickness of 5.5 mm is the minimum.关键词：arc characteristics;DC contactor;temperature distribution;magnetic field intensity10|148|1更新时间：2025-04-26
- 摘要：Winding deformation is one of a primary causes of transformer failures. Frequency response analysis (FRA) is a common method for detecting such deformation fault. In view of such issues as weak fault diagnosis effect, weak noise resistance and imperfect monotonicity fault degree index and and actual fault degree due to insufficient explanation of frequency response data in the actual application, the condition discrimination method of transformer based on dynamic time warping (DTW) and the K-nearest neighbor (KNN) algorithm as well as fault characterization method leveraging DTW deviations are proposed. Based on the operation on a set of actual transformer and a set of model transformer, their performance in the aspect of winding status identification and characterization of fault degree of the winding are verified. The accuracy, noise resistance of the method in the winding condition identification and sensitivity as well as linear correlation in the characterization of fault degree are analyzed through comparison and experiment. The result shows that in these two cases the method, compared with the existing winding fault diagnosis standard of transformer, has higher accuracy, can reflect the degree of winding deformation of transformer and has better noise resistance performance.关键词：transformer;frequency response;DTW algorithm;winding deformation;fault diagnosis10|179|2更新时间：2025-04-26
- 摘要：For studying explosion-proof ability of the OLTC, the OLTC of converter transformer is taken as the research object and the explosion-proof test system of OLTC is set up. A pair of electrodes are set inside the OLTC. After the test high current passes through the small copper wire between of the electrodes and keeps it to fuse, an arc channel is formed between the electrodes. The different fault energy is obtained by adjusting the arc current, arc clearance and arcing duration and the pressure inside inside the OLTC is measured under the energy. The pressure in the oil chamber of OLTC is calculated and compared under the corresponding energy. The test research shows that: ①the explosion-proof ability of the OLTC is limited. It is suggested to improve the strength of the OLTC cover and achieve the explosion-proof ability of the OLTC in combination with the rupture disc. ②In order to avoid the excessive variation of arc voltage with the increase of arc energy, it is suggested to reduce the electrode clearance. ③For avoiding electrode erosion, it is recommended to use materials with small specific heat capacity and low melting point. It is recommended to change the electrode into hemispherical configuration so to assure stability of the arc.关键词：converter transformer;OLTC;arcing;explosion-proof;energy;electrode10|175|0更新时间：2025-04-26
- 摘要：For comparing the influence of different types of impulse currents on DC aging of Zinc oxide (ZnO) varistors, the same type of Zinc oxide varistor samples are used to carry out 2 ms square wave (peak at 2 kA) withstand test and 4/10 μs impulse current (The peak value is 100 kA) test. The experimental results show that under the impulse withstand of 1-3 rounds (3-9 times), the 2 ms square wave has a definite optimization on the aging characteristics of the ZnO varistor. While, the high current impulse at 4/10 μs keeps the ZnO varistor’s aging characteristics continue to deteriorate. The scanning electron microscope (SEM), spectrometer, digital source meter are used to study its microstructure and electrical performance parameter changes. The reason is analyzed in combination with the experimental results, the damage degree of the 4/10 μs impulse current to the ZnO varistor is greater than that of the 2 ms square wave impulse current, which is more likely to cause the aging of ZnO varistor. Under the 2 ms square wave withstand for 1-3 rounds (3-9 times), the aging characteristics of varistors can be improved. The reason is that the thermal effect due to impulse current makes the interstitiated Zinc ion, which is a metastable component of the grain boundary barrier, react in the grain boundary and reduce its concentration, and obtain a more stable grain boundary junction than before the impact, thus improving its aging characteristics.关键词：ZnO varistor;impulse current;aging character;heat treatment;grain boundary11|86|0更新时间：2025-04-26
- 摘要：In this paper, the regional distribution characteristic of the decay-like break fault of composite insulator in China is summarized on the basis of investigating the decay-like break fault of the composite insulator which happened from 2010-2020 in State Grid of Corporation Company in China. The decay-like break fault of the composite insulator is mainly located in the eastern coastal and southern regions of China. According to the statistics, about 90% of faulty insulators are located in areas where the annual rainfall is above 500 mm, and the relative environmental humidity is above 60% before the fault. The Decay-like break may occur at any ambient temperature, but mainly concentrates in the ambient temperature above 20 ℃. Except for ambient temperature and humidity, the distribution of decay -like break fault has no obvious correlation with other such natural factors as terrain, altitude and wind. The operating condition related to the decay-like break fault is voltage level and string type. It is confirmed through electric field calculation that excessive partial electrical filed strength on the high voltage side is not the reason of multiple occurrence of decay-like break of 500 kV composite insulator on V strings, but the important reason that the decay-like break fault is distributed in the line insulator at voltage level of 500 kV.关键词：composite insulator;decay - like fracture;environmental factors;operating status;electric field calculation11|78|0更新时间：2025-04-26
- 摘要：Vigorous development of UHV GIL equipment is an important way to solve the need of large power transmission in China under the ‘Double Carbon’ background. However, due to the short application history of UHV GIL, the reliability of its key components needs to be improved. Especially in recent years, flash-over or breakdown of GIL tri-post insulators have occurred frequently, which faces such critical status as unclear fault mechanism, insufficient optimization method and lack of detection means. Based on the brief introduction to the composition structure and types of tri-post insulators for UHV GIL, the related faults of the operated GIL projects in recent years in China are counted, and the problem of the tri-post insulators of the current EHV/UHV GIS in such stages as design, manufacture, installation, operation and maintenance is systematically analyzed from such multiple perspectives as material selection, process improvement, structure optimization and improvement of test and detection technology. The variety of improvement measures are proposed and the suggestion direction for the subsequent research is given, which can provide useful reference for product improvement and fault rate reduction of EHV/UHV GIL tri-post insulators.关键词：GIL;UHV;tri-post insulator;epoxy composite material;surface charge10|86|1更新时间：2025-04-26
- 摘要：For monitoring the operating status of Zinc oxide surge arrester in real-time, an online monitoring method for Zinc oxide surge arrester considering the interference of voltage acquisition electromagnetic signals is proposed. The empirical mode decomposition method is used to remove electromagnetic noise from the original voltage signal and eliminate electromagnetic interference. The harmonic analysis method is used to implement the fast Fourier transform operation on the voltage and current signals, simplify the operation, obtain the resistance, fundamental wave resistance and third harmonic current of the lightning arrester, and thus determine the operating status of the Zinc oxide lightning arrester. The experiment proves that this method can effectively remove electromagnetic noise and useless information, retain effective information and the measurement error does not exceed 0.25%. It can effectively monitor the operating status of Zinc oxide lightning arrester.关键词：voltage acquisition;electromagnetic interference;zinc oxide arrester;harmonic analysis;discrete spectrum correction11|96|0更新时间：2025-04-26
- 摘要：With the proposal of the ‘two-carbon’ policy, the exploration of environmentally friendly SF6 alternative gas has attracted more and more attention. And the insulation characteristics of various gases are an important parameter concerned. However, due to instability of arc, it is difficult to measure the electron number density of the arc discharge in the circuit breaker. The electron number density is an important parameter to determine the successful interruption of the circuit breaker. As an optical diagnosis method for plasma, Thomson scattering has such the advantage as high accuracy without the assumption of equilibrium state. In this paper, the Thomson scattering method is used to measure the radial electron number density distribution of the arc formed by pulling the arc in the air, N2, CO2 and SF6 at 250 A and 200 V. It is found that there is little difference in the radial electron number density distribution of the arc in the four different gas medium during arcing stage. The electron number density of the arc center is around 1×1023 m-3. The electron number density of the arc boundary is about 6.0×1022 m-3. In general, the radial electron number density of SF6 is lower than that of air, which is related to the strong electronegativity of SF6.关键词：gas arc;optical diagnosis;Thomson scattering;electron number density9|49|0更新时间：2025-04-26
- 摘要：Cellulose pressboard by nano-TiO2 modification can enhance its breakdown field strength and anti-aging performance and is presently the research hot spot in the field of electrical insulation. However, it is still unclear how the nanoparticles in the pressboard affect the energization of transformer oil flow. In order to reveal the energization influence and suppression mechanism of nanoparticles in oil flow, it is necessary to measure and analyze the oil flow energization characteristics in the pressboard by nano-TiO2 modification. In this paper, the pressboard by nano-TiO2 modification and the unmodified mineral oil are taken as the research objects, and the electrostatic current is measured by rotating a disk system. Based on the control variation method, the influence of temperature, nano particle mass fraction and flow rate on the energization degree is studied, and the mechanism of nanoparticles on the energization of oil flow is analyzed. The finite element analysis method is used to analyze the simulation model of the transformer oil duct, and the electric field distribution in the transformer oil duct, which is made with the pressboard by nano-TiO2 modification with different contents, is compared. The research results show that, compared with the unmodified pressboard, the addition of 1% nano-TiO2 particles in cellulose pressboard can inhibit the energization of oil flow and minimize the electric field distortion after the accumulated energization in the oil duct. The research results in this paper can provide a new method for suppressing the oil flow energization in transformer.关键词：nano modification;electrification measurement;finite element analysis;insulating pressboard;electric field distribution8|68|0更新时间：2025-04-26
- 摘要：For developing high-power gas spark switch with simple structure and convenient maintenance, a multi-gap gas spark switch with atmospheric pressure air corona equalization is developed. The switch adopts corona discharge equalization mode and consists of nine identical gaps. The electric field of the nine-gaps gas spark switch with corona equalization is analyzed by finite element method. It is found that the suitable length corona needle has little influence on the electric field of the main gap of the switch, and, in case of loading trigger pulse, the strong distortion electric filed can be formed in the middle gap. On the basis of theoretical analysis, the study of breakdown characteristic of the multi-gap gas spark switch is developed. The experimental results show that corona equalization is beneficial to improve stability of the switch. The self breakdown voltage dispersion of the switch is reduced and the self breakdown voltage is slightly increased. At the same time, a good triggering characteristic of the multi-gap switch is obtained. In the range of working voltage 60~85 kV (the working under-voltage ratio is 56.8%~80%), the breakdown delay jitter of the switch is less than 20 ns. When the working voltage reaches more than 80 kV, the jitter can be less than 10 ns. The multi-gap gas spark switch with atmospheric air pressure corona equalization can be used in such pulse power systems as linear transformer driver. The method used to optimize the electrode structure on the basis of electric field simulation has reference significance for the design of other types of switchgear.关键词：pulse power technology;multi-gap gas spark switch;low jitter;voltage balance8|206|0更新时间：2025-04-26
- 摘要：In view of such issues of metal grounding material, which is widely used in power systems, as serious corrosion and high maintenance costs in operation, the new corrosion-resistant flexible graphite grounding material has become a popular research direction. Since the electrical and thermal characteristics of the flexible graphite grounding material are quite different from those of traditional metal grounding material, its thermal stability performance under power-frequency current is also different from that of metal material, which becomes the main factors restricting the selection of cross-section and structural design of flexible graphite grounding material. In order to obtain more accurate thermal stability performance of flexible graphite grounding material, the experimental research on the electrical and thermal characteristics of flexible graphite grounding material under different short-term power-frequency currents is performed, and the corresponding thermal stability temperature thresholds and thermal stability ratio are obtained. The research results show that the maximum allowable working temperature (thermal stability temperature threshold) of the flexible graphite grounding materials is about 300 ℃, which is closer to the traditional metal grounding material; and its thermal stability ratio is about 2.94, which is lower than that of metal grounding material. Therefore, in case of designing the grounding body, only the section of the grounding body of the flexible graphite material exceeds that of the metal grounding material, can the current capacity meet the actual needs be assured.关键词：graphite-based flexible grounding body;power-frequency thermal stability;thermal stability ratio8|35|0更新时间：2025-04-26
- 摘要：O2 has a significant influence on SF6 decomposition products under the arc discharge of SF6 gas insulated switchgear, but its influence and related action mechanism are unclear for now. To this problem, the arc discharge experiments using 18O2 as a tracer is performed in this paper, the variation of 18O isotopic substances during and after discharge by GC-MS is analyzed, the generation path of SF6 decomposition products under arc discharge and the influence of 18O2 on SF6 decomposition products are defined as well as its deep chemical reaction mechanism is clarified. The results show that under arc discharge, O2 impurities will promote generation of SOF2, SO2, SO2F2, and CO2 to varying degrees, in which O2 mainly participates in the generation reactions of SOF2, SO2, and CO2 in the form of decomposed O atoms, and participates in the generation reactions of SO2F2 in the form of both O2 molecules and decomposed O atoms. The generation of SOF2 and SO2F2 is mainly dominated by the composite reactions during the discharge, while the generation of SO2 is mainly dominated by the intermolecular reactions after the discharge. And the generation of CO2 comes from the combination of the two aspects.关键词：SF6 decomposition products;arc discharge;influence characteristics;oxygen isotope tracer method9|35|0更新时间：2025-04-26
Research & Analysis
- 摘要：Huge power transmission system is one of the most important infrastructures in China and to assure its safety and reliability under the action of long term wind load is the key to be concerned. In this paper, a refined finite element model of transmission tower-line system is set up by Abaqus and the wind loads are simulated. Considering the instability of the stressed bar, the response of tower line is analyzed by the dynamic calculation method and, on this basis, its weak position is determined. Furthermore, the stress time history of weak bar is taken as a index, the life of tower line at different wind velocity is predicted by using the rain flow method on the basis of the damage law described by the Miner linear criterion. Then, the influence of the key parameters of wind load simulation on the structure prediction life is studied and the liner is comprehensively assessed. The results show that taking the structure failure as the failure criterion of the whole tower line system can provide a definite reference for life prediction of system. The prediction life of structure is mainly controlled by the weak structure main element (main material of slope place). In addition, the parameters of wind load simulation has large influence on the prediction life. The difference between different simulation time is large. Kaimal spectrum model is more conservative than that of random Fourier spectrum. And rough length is negatively correlated with prediction life.关键词：transmission tower-line system;wind load;rain flow method;life prediction10|73|0更新时间：2025-04-26
- 摘要：With the development of science and technology, multiple important issues are faced in the active distribution network. Firstly, with the access of a large number of flexible loads and electric vehicles the type of loads shows obvious diversification and the complexity of the grid management is increased. Secondly, the randomness and fluctuation of renewable energy sources present significant challenges to the grid fault recovery. To deal with these issues, a fault recovery strategy for the active distribution network concerning diverse energy interactions is proposed. This strategy sets up an optimization with the maximizing controllable distributed generation actions and minimizing power loss as the goal and, at the same time, system security constraints are met. For solving the model, an improved binary particle swarm optimization algorithm and genetic algorithm are used. The experimental result shows through simulation analysis on the IEEE33 node distribution model that the strategy can not only effectively reduce the grid loss and recover the power loss to the greatest extent, but also provide a kind of potential solution for the grid management to the challenge of renewable energy and multiple loads.关键词：active distribution network;flexible load;renewable energy;fault recovery;particle swarm optimization algorithm9|164|1更新时间：2025-04-26
- 摘要：In view of the demand of wireless temperature technology for power equipment, a kind of wireless temperature online monitoring system based on a new type of magneto electric power generation device is designed in this paper. The system uses the stray magnetic field around the power system to power the entire wireless monitoring system, and designs a new piezoelectric friction-coupled cantilever beam structure to improve the efficiency of magnetic field energy collection. At the same time, the temperature measurement module uses low-pass filtering to improve the collection sensitivity. The low main frequency working mode and timing wake-up function are used to reduce the energy consumption of signal processing and transmission. It has both low-power temperature acquisition function and concurrently electrically isolated data transmission capability to assure stable and reliable operation of the whole set of equipment. It is known by the experiments that the power module can generate a peak-to-peak open-circuit voltage of 160 V under an alternating magnetic field of 4 Oe, 50 Hz and the stable voltage at 3.3 V is output after rectification of a short-circuit current at 14 μA. The wireless temperature measurement device can send and receive temperature data every 5 s under the power supply.关键词：on-line temperature monitoring;micro-energy harvesting;coupled cantilever beam structure9|75|0更新时间：2025-04-26
- 摘要：For finding a suitable epoxy formula material with better hydrophobicity and tracking resistance for the air insulated switchgear cabinet for the application in coastal area and adaption of the salt spray and humid environment conditions there, 2% active SiO2 nanoparticles, 2% Al2O3 nanoparticles and 6% Al(OH)3 particles are added to the injection epoxy formula, the commonly used recipe for switchgear cabinet. It is concluded that through the measurement of contact angle and electrical resistance trace characteristic that the addition of active SiO2 nanoparticles, Al2O3 nanoparticles and Al(OH)3 particles nanoparticles in the epoxy resin material formula can effectively improve the hydrophobicity and tracking electrical resistance trace. The tracking electrical resistance of original formula is improved from 1A0 to 1A2.5, at the same time, the mechanical performance is slightly changed.关键词：switchgear cabinet;additives;epoxy formula;hydrophobicity;tracking electrical resistance9|27|0更新时间：2025-04-26
Technical Discussion
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