最新刊期
卷 60 ， 期 12 ， 2024
- 摘要：Shell potential rise is a critical issue in the operation of gas insulated transmission lines (GIL). When a hybrid transmission line suffers from lightning strike or asymmetrical short circuit faults, a significant induced potential will be generated on the three-phase common box GIL shell. For the three-phase common box GIL shell potential rise problem, there is a lack of corresponding shell potential rise inhibition strategy research. Therefore, this paper relies on the actual engineering, the establishment of 220 kV three-phase common box GIL hybrid transmission line equivalent circuit model, analysis of the principle of GIL shell potential rise under different operating conditions and the factors affecting the proposed shell potential rise inhibition strategy, and through the electromagnetic transient simulation for verification. The study shows that：when a single-phase grounded short-circuit fault occurs, the shell potential rise is the largest. When there is a lightning intrusion wave, the GIL shell appears obvious potential rise phenomenon. Erection of lightning arrester and the use of both ends of the centralised grounding method can effectively inhibit the phenomenon of the potential rise of the common box-type GIL.关键词：three-phase common box gas-insulated transmission lines;hybrid transmission line;shell potential rise;suppression strategy;grounding optimisation195|41|0更新时间：2025-04-26
- 摘要：The complex and variable external environment temperature in the installation process of GIS has a non-negligible impact on the installation positioning deviation and internal forces of structure part, causing a large difference between the complete installation state and the design state. Based on an actual substation project and in combination with the local temperature environment of the project, four different temperature variation conditions are set up. The birth and death element method based on the time-varying mechanics is adopted for the finite element simulation analysis of the installation process of GIS and the influence of temperature effect on structural displacements and stress during the installation process is studied. The simulation results show that the temperature variation in the installation process has a cumulative effect on the displacement deviation of GIS bays, and the displacement deviation will affect the installation positioning requirements. The base is connected by the bolt with less rigidity which, in case of significant temperature effect, has no way to coordinate the deformation of the upper structure and the lower frame. With the temperature variation during the installation period, the stress of the enclosure varies correspondingly but with small stress value, relative large internal force of bolt and small safety margin. The study result will lay the foundation for control of installation environment structure optimization for the GIS structure.关键词：GIS;birth and death element method;temperature;deviation analysis81|23|0更新时间：2025-04-26
- 摘要：Condensation is one of the main causes of failure of switchgear. Aiming at the internal condensation of high-voltage switchgear, type KYN28A-12 switchgear cabinet is taken as the research object in this paper, a condensation numerical simulation model of switchgear based on finite volume method is set up. The temperature and humidity field distribution inside the switchgear under steady-state conditions is obtained. The influence of ambient temperature, ambient relative humidity and load current change on the temperature and humidity distribution and condensation inside the switchgear is analyzed and the condensation mechanism inside the switchgear cabinet is discussed. The results indicate that the inside of the switchgear shows such characteristic as high temperature of the current-carrying conductor, low surface temperature of the contact box and the circuit breaker enclosure, and high relative humidity. When the temperature in the cabinet is decreased by about 12 K, the relative humidity is increased to saturation and condensation is formed. The environmental humidity increases and the load current changes, no condensation is generated in the switchgear for a short time.关键词：high voltage switchgear;temperature field;humidity field;wall condensation model;numerical simulation107|28|0更新时间：2025-04-26
- 摘要：For effective fault status diagnosis of circuit breaker, a kind of fault classification method of circuit breaker based on the improved phase trajectory characteristics of the opening and closing coil current is proposed. First, the phase space reconstruction method is used to process the current data of the opening and closing coils of five fault status, and the mutual information method and pseudo-nearest neighbor algorithm are used to determine the delay time τ and the embedding dimension m respectively, and the current signal is reconstructed into high-dimensional space to obtain the phase trajectory. Then, the 5D fault feature set is constructed by adopting 2D overall morphological characteristics of the phase trajectory and, at the same time, the 3D local inflection point features is introduced to improve the difference of phase trajectory characteristic of different types of faults. Finally, the fault characteristic set is used as the diagnosis basis input to construct the fault diagnosis model of circuit breaker based on support vector machine. The real sample analysis results show that the method proposed in this paper can accurately and stably extract the phase space characteristics of fault current signal and achieve more efficient fault diagnosis of circuit breaker.关键词：circuit breaker;current of opening and closing coil;phase space reconstruction;improved phase trajectory feature64|23|1更新时间：2025-04-26
- 摘要：Marine circuit breaker is an essential basic device in power system of ship, and its performance under the dynamic shock load is directly related to the safety of the entire power system of the ship. For studying the factors affecting the shock resistance of circuit breaker, the circuit breaker model is set up in this paper, and the dynamics design analysis method (DDAM) and the time domain analysis method are used for simulation and study. The design is optimized for the insufficient structural strength and verified by the shock test. The conclusions and methods obtained provide references for further improving the shock resistance of the circuit breaker.关键词：shock resistance;marine circuit breaker;time domain analysis;dynamics design analysis method (DDAM)39|17|0更新时间：2025-04-26
- 摘要：In view of partial discharge phenomenon of composite bushing and connecting copper bar area in the compartment of a certain type of 40.5 kV gas insulated ring main unit, which leads to the reduction of the insulation performance of the ring main unit, the SolidWorks software is used to set up a three-dimensional model of the composite bushing and connecting copper bar area, and then Ansys Workbench finite element analysis software is used to simulate the electric field of the composite bushing and connecting copper bar area. The results show that the electric field is concentrated on the end of the hexagon socket cylindrical head screw, top of the stationary contact of arc initiation, top of the connecting copper bar and the bending position of the connecting copper bar. On this basis, such four structural optimization measures as change of the type of hexagon socket screw, addition of a grading shield on the top of the stationary contact of arc initiation, increase of the bending radius of the rounded corner connecting copper bar the increase of the distance between the connecting copper bar and the front panel of the enclosure are adopted to effectively reduce the electric field intensity near the composite bushing and connecting copper bar area. Finally, the optimized composite bushing and connecting copper bar are assembled and the prototype has passed the insulation test verification.关键词：40.5 kV ring main unit;composite bushing;connecting copper bar;electric field simulation;structure optimization55|34|0更新时间：2025-04-26
- 摘要：High frequency and high amplitude inrush current will be generated in the process of switching capacitor bank of SF6 circuit breaker. Under the effect of both pre-breakdown arc ablation and post-arc mechanical wear, the switching erosion of the arc contact of SF6 circuit breaker will aggravate and affect its service life. Therefore, the switching erosion characteristics of arc contact of SF6 circuit breaker are studied in depth in this paper. Arcing experiments and making inrush current experiments are performed based on the equal charge method, and the contact erosion morphology, pre-breakdown arcing time, contact resistance and mass loss are obtained. The simulation model is set up according to the operating conditions of the arc contact, and the temperature field variation and contact collision process of the moving and stationary arc contacts are analyzed. The results show that the post-arc mechanical wear is an important part of the making erosion of the arc contact. With the increase of the peak value of the inrush current, the proportion of mechanical wear increases. When the inrush current is 15 kA, the mass loss due to mechanical wear accounts for 32.25% of the total mass loss. Under the ablation of pre-breakdown arc, the performance of contact material changes, and the contact surface becomes rough. After contact of the arcing contact, the mechanical wear of the contact is aggravated due to the change of material physical parameters. In case of next making operation of circuit breaker, the prior erosion makes the contact gap easier to breakdown and the ablation time becomes longer, thus making the mechanical wear more serious.关键词：SF6 circuit breaker;arc contact;making erosion;inrush current;mechanical wear60|24|0更新时间：2025-04-26
- 摘要：The distribution parameters of high-frequency transformer can affect its output parameters and performance. It is found by deriving the analytical expressions for the secondary distributed capacitance and leakage inductance of high-frequency transformer that the winding mode, segment and layered structure, insulation layer thickness, winding height and insulation medium are the main factors affecting its distribution parameters. A finite element simulation model of electromagnetic field is set up for high-frequency transformers at 40 kV and 20 kHz, and the influence of various factors on distributed capacitance and leakage inductance is calculated and analyzed. The insulation thickness and height of the transformer winding are determined by way of optimizing the segment and layered structure of the secondary winding and of comprehensively considering leakage inductance, distributed capacitance and the winding losses and, on this basis, the experimental prototype is designed and processed. The test results show that the errors between the simulation calculation results of distributed capacitance and leakage inductance and the actually measured values are 9.5% and 11.3%, respectively. The simulation analysis method and relevant conclusions provide a reference for the calculation of distributed parameters and structural design of high-frequency transformer.关键词：high-frequency transformer;distributed capacitance;leakage inductance;winding loss;finite-element simulation of electromagnetic field40|18|0更新时间：2025-04-26
- 摘要：Hot spot temperature is an important parameter which directly affects insulation life of power electronic transformer. For guiding reasonably insulation epoxy encapsulation design of the power electronic transformer, the equivalent model of 220 kW/30 kHz power electronic transformer is constructed, and the influence of the thermal conductivity of epoxy insulating material on temperature distribution characteristic of transformer at different operation conditions. The results show that the hot spot temperature of power electronic transformer with coaxial distribution of high and low voltage windings is mainly located at the height which is 56% from the bottom of winding, and it gradually increases with the increase of load coefficient. In the case of short circuit, the hot spot temperature of high and low voltage windings rises at the speed of 8 ℃/s and 22 ℃/s respectively. The hot spot temperature of the transformer decreases significantly with the increase of the thermal conductivity of the epoxy insulating material. When the thermal conductivity of the epoxy insulating material is higher than 1.1 W/(m·K), the hot spot temperature variation tends to be gentle. At this time, the temperature distribution of the transformer meets the requirements of China national standard GB/T 1094.11—2022 specification and has a load margin of 30%. The research work can provide theoretical reference for the design of epoxy insulation encapsulation of power electronic transformer.关键词：power electronic transformer;finite element analysis;fluid-solid-structure coupling;temperature field analysis32|19|0更新时间：2025-04-26
- 摘要：Metal particles mixed into the bushing on the valve side of the converter transformer and cracks in the capacitor core are common faults at present. The research on electric field distribution of the bushing under different voltages and the influence of defects on the electric field distribution are of great significance to the optimization design and failure analysis of the bushing. In this paper, the ±800 kV UHV converter transformer bushing is taken as a prototype, a ±72.5 kV epoxy-impregnated paper capacitive bushing simulation model is set up, the potential and electric field distribution of the bushing under AC and DC voltage is calculated, and the influence of two defects on the electric field is researched. The results show that the bushing, in case of containing metal particles or crack defects, has a greater influence on the distortion of the electric field. The research results not only provide a basis for the subsequent analysis of partial discharge tests of different defects in the scaled bushing model, but also provide a reference for the optimal design of epoxy-impregnated paper capacitive bushing.关键词：valve side bushing of converter transformer;electric field;finite element simulation;defect analysis33|21|0更新时间：2025-04-26
- 摘要：Aiming at such issues as low detection accuracy and slow speed of multi-defect detection of insulator, a kind of improved YOLOv5 accurate detection algorithm for multi-defect detection of insulator (YOLOv5-GSEM) is proposed. Firstly, GhostNet structure is introduced to replace C3 module of the original YOLOv5 backbone network to improve the network computing speed. After SPPF, the non-parametric attention module SimAM is introduced to enhance the effective features and suppress the interference features. Secondly, the enhanced feature pyramid network (EFPN) and the multiscale feature fusion network (MFFN) are introduced to fully integrate multiscale features and improve the detection accuracy of multi-defects of insulator by the network. The experimental results show that the average of the accuracy of the model (mAP0.5) proposed in this paper reaches 87.8%, which is 2.7% higher than that of YOLOv5 algorithm, and the detection speed is increased by 4.6%. The proposed network provides a more effective method for the detection of various defects of insulator.关键词：multiple defect detection of insulator;attention mechanism;enhanced feature pyramid network (EFPN);multiscale feature fusion;lightweight36|20|0更新时间：2025-04-26
- 摘要：For assuring safe operation of 66 kV resonant grounding system, such two parameters as the damping resistance and the detuning degree of the arc suppression coil need to be reasonably configured. However, the distributed compensation operation makes the parameter setting difficult. In this paper, a kind of decentralized compensation strategy is proposed, which considers such core data as residual current, recovery speed of faulty phase voltage, residual value of the zero-sequence voltage decay after the fault, and the displacement degree. It is obtained by way of experiment that the faulty residual current shall be less than 7 A and the recovery speed of faulty phase voltage shall be lower than 500 V/ms. On this basis, the parameter optimization constraint equation is proposed, and the gradient descent method is used to obtain the maximum value of detuning degree and the minimum value parameters of damping resistance. Finally, an actual 66 kV resonant grounding system is used as an example to verify the effectiveness of the proposed compensation strategy by simulation.关键词：66 kV resonance grounding system;detuning degree;damping resistor;parameters adjust29|16|0更新时间：2025-04-26
- 摘要：Compared to mechanical circuit breaker, DC solid-state circuit breaker (SSCB) composed of semiconductor devices has great advantage in response time. The Si/SiC cascode element consisting of low-voltage silicon metal-oxide-semiconductor field-effect transistor (Si MOSFET) and high-voltage silicon carbon junction field-effect transistor (SiC JFET) has excellent switching characteristics. The reliability of semiconductor power element has always been the focus of DC SSCB. The test of the unclamped inductive switching (UIS) is an important method to assess reliability of the semiconductor power element. In this paper, the avalanche performance of Si/SiC cascode element during the UIS period is analyzed by means of experiment and simulation. Firstly, the avalanche performance under different load currents is obtained by increasing the on-time of the element. The results show that with the increase of the on-time the Si/SiC cascade element shows an abnormal performance of the avalanche-voltage drop during the avalanche period. Then, UIS tests is performed through a discrete Si/SiC cascode element, finding that the abnormal performance originates from the turn-on of SiC JFET during avalanche period. Finally, the 3D electrical-thermal coupling simulation of the Si/Sic cascade element is performed. The results show that the temperature of aluminum metal layer and bonding wire of SiC JFET rises during the avalanche period, leading to the increase of the gate equivalent-resistance of SiC JFET, and ultimately resulting in the turn-on of SiC JFET during the avalanche period.关键词：solid-state circuit breaker;Si/SiC cascode device;avalanche performance;electrical-thermal coupling simulation21|14|0更新时间：2025-04-26
- 摘要：According to the actual situation and demand of electric test operation of high-voltage transmission line, a kind of non-contact AC electroscope for 10 kV and 35 kV transmission lines is studied. The electric field sensor with electromagnetic induction as principle is used as the induction probe to analyze the measurement mechanism of the sensor and explore the influencing factors of the sensor measurement results. The Maxwell software is used to simulate the electric field distribution around the transmission line, and the influence of sensor parameters on the performance under different live conditions is analyzed so to provide theoretical guidance for the structural design of the electroscope. The hardware circuit of the electroscope is designed and the software control system is designed at the same time. The the prototype of the electroscope is made, the test experimental circuit is set up to test the prepared electroscope and verify the effect of the electroscope. The test results show that under the high voltage electric field environment, the sensor's induced voltage of the sensor conforms to the law of electric field induction, the electroscope can perform qualitative electric test and has practical significance.关键词：electroscope;non-contact;electromagnetic induction;electric field simulation28|17|0更新时间：2025-04-26
- 摘要：In order to solve the problems of the excessive amount of superconducting tape and the excessive heat leakage power of the current lead due to the superconducting component participating in the normal current flow of the traditional resistive superconducting current limiter, the topological structure of a new type of hybrid superconducting current limiter which is suitable short circuit protection of DC power supply suitable for medium voltage ships is proposed. The joint commutation process based on IGBT and high-speed vacuum switch is experimentally researched and theoretically calculated, and the influence of capacitance, inductance, resistance and other parameters on the commutation process is obtained；The inductance of the high-temperature superconducting assembly, which is composed of superconducting tape discs which is made by the disc non-inductive winding, is only 2.6 μH；The contact movement characteristics of the high-speed vacuum switch for the current limiter are introduced；Finally, the prototype of the current limiter is tested, and the prototype successfully limits the short circuit current with the prospective peaks of 57.6 kA within 24 kA. The commutation of current at 7.7 kA is completed under the condition of the short-circuit current rise rate at 34 A/μs, the commutation time is only 61 μs, and the maximum capacitor voltage is 1 170 V. The arc-free breaking of the high-speed vacuum switch is achieved.关键词：hybrid superconducting fault current limiter;medium voltage DC;fast commutation;high speed vacuum switch;breaking without arc28|19|0更新时间：2025-04-26
- 摘要：In view of heat dissipation in the design of 150 kW high-power-density electronic DC transformer power module, the principle of heat loss of high-frequency conductor is studied. The temperature rise is calculated by electromagnetic thermal coupling simulation. The conductor structure is improved from the mechanism of eddy current loss, the effectiveness of reducing heat loss is analyzed by simulation, and the temperature rise of conductor and module structure is reduced to less than 30.5 K. The parameters of fin of the aluminum base radiator in the module of high voltage side is optimized, but the temperature rise of the IGBT & SiC is still too high. The new and high efficiency radiator is developed in combination with the vapor chamber soaking technology. It is verified from the theoretical analysis of thermal resistance and temperature rise simulation that the thermal conductivity of the vapor chamber reaches 4 000 W/(m·K), and the temperature rise of the power element is reduced to 31.9 K. Finally, the test platform is set up and the temperature rise of the developed power module prototype is operated at rated power. It is measured that the power density of the module reaches 1.92 kW/L and the important elements meet the temperature rise target, thus the reliability of the power electronic modules, at the time of compact integration, is also assured at the same time.关键词：high power density;temperature rise control;high-frequency-current conductor;vapor chamber;test platform23|19|0更新时间：2025-04-26
- 摘要：The zinc oxide cable sheath protector in power system is an important equipment to assure the safety of the cable supply and its operating condition will directly affect the safety of the line. Due to the long-term influence of various overvoltages, the cable sheath protector is susceptible to aging, resulting in significant deterioration of its performance. The leakage current analysis-based condition detection is important for predicting the aging state of the cable sheath protector. In this paper, the high frequency characteristics of the cable sheath protector after impact aging are studied by using the lightning impulse aging method, and a diagnostic test index for the aging state based on the high harmonic ratio of the leakage current is proposed, which tends to increase gradually with the increase of aging. Therefore, it can be used to effectively assess the aging state of the cable sheath protector and provide technical support for the detection of the aging state of the cable sheath protector.关键词：cable sheath protector;aging condition;leakage current;high frequency characteristics;harmonic ratio29|16|0更新时间：2025-04-26
- 摘要：To study the prediction of audible noise of transmission lines under the influence of multiple environmental factors at high altitudes, such three audible noise observation stations as 20 m, 30 m and 35 m away from the side phase are set up under the 500 kV double-circuit line on the same tower at the altitude of 2 400 m. At the same time, the meteorological station is used to collect data on multiple environmental factors. In this paper, a kind of convolutional neural network (CNN)-bi-directional long short-term memory (BiLSTM) model based on the multi-head attention (MHA) mechanism is proposed for audible noise prediction. Firstly, the Pearson correlation analysis is used for calculation, comparison and elimination of correlation degree of various environmental factors data. Then, in order to fully mine the temporal features of the audible noise data, CNN is used for feature extraction of the multiple environmental factors data. Then, the extracted feature vectors are input to BiLSTM for training, and the multi-head attention mechanism is introduced at the BiLSTM side to make the model learn data features with higher weight, thus improving the prediction accuracy of the model. The results show that the combined model constructed by this method can improve the prediction accuracy of the audible noise data considering multi-factor features and has good generalization.关键词：audible noise of transmission line;multi-environmental factors;convolutional neural network;bi-directional long short-term memory;multi-head attention25|18|0更新时间：2025-04-26
- 摘要：With the advancement of the interconnection process of power grid, the regional power grids are connected as a whole by tie lines, in which, the unbalance of power flow distribution during the operation of the multiple parallel lines may be occurred and the safe and stable operation of the power system may be threatened. In view of this issue, a topological structure of electromagnetic power flow controller composed of voltage phase shifter and voltage regulator in series is proposed. The power flow regulation mechanism is analyzed, and an electromagnetic power flow controller control strategy for power balance regulation of multiple parallel lines is proposed. The three-phase power system circuit equation is transformed into dq coordinates through coordinate transformation to achieve independent control of active and reactive power of the regulating circuit. The simulation results of the two-line in parallel show that the proposed control strategy can be well applied to the electromagnetic power flow controller. It has a good regulation effect for the power system with load fluctuation and small regulation error. The adoption of electromagnetic power flow controller has a high economical efficiency and durability.关键词：multiple parallel lines;electromagnetic power flow controller;power flow balance;decoupling control22|16|0更新时间：2025-04-26
- 摘要：With the development of unmanned aerial vehicle (UAV) and various control technologies, UAV patrol technology is widely used in the power grid. At present, there are still some shortcomings in the obstacle avoidance of UAV operating in electromagnetic field environment. For studying the influence of the operating transmission line on the surface electric field strength of UAV during patrol inspection, the models of tower, wire, DJI M300RTK UAV, electric field sensor are set up by SolidWorks software, then imported into the finite element simulation calculation software Ansoft Maxwell to perform overall electric filed calculation. One most suitable voltage is obtained by changing the voltage angle as the power transmission line setting voltage of electrostatic field simulation. And the influence on surface electric field of the UAV from such positions as UAV shape, wing, sensor location is simulated and studied in different distance conditions. The influence of power transmission line on UAV surface field strength under different conditions is obtained by simulation and the research results in this paper can provide data reference and theoretical basis for the patrol strategy of UAV at site.关键词：UAV;rotor;electric field simulation;model;transmission line26|15|0更新时间：2025-04-26
- 摘要：Recently, the transmission lines frequently experienced such accidents as wind deviation flashover in Xizang due to its high-altitude and windy environment, with transmission lines with ‘cup-type’ steel tower with an extraordinary characteristic of uneven body shape in particular. In view of this, the research on the design of wind induced vibration and vibration coefficient of ‘cup-type’ tower-line system of transmission line project in Xizang is performed in this paper in order to provide necessary theoretical basis for the reasonable wind resistance design of related transmission line. The research process and method is the ‘cup-type’ transmission tower-line section with actual fault in Xizang is taken as the research object. The wind induced vibration simulation and analysis method of the transmission tower and line system, namely Davenport wind power spectrum and AR model, is used to simulate the fluctuating wind load and apply to the finite element model of the transmission tower-line system to calculate the dynamic response and wind induced coefficient of the transmission tower in combination with random vibration theory. The method is used for simulation and analysis of the transmission line to discuss the vibration response characteristics and the wind induced coefficient influence of the tower-line system under strong wind environment and different wind angels. Then, the simulation result is compared with the existing design specification to verify the unreasonable phenomena existed in the wind resistance design of the existing specification and to be improved. On this basis, the design correction formula of wind vibration coefficient of the transmission tower-line system is proposed in this paper, which has the overall error within 10% and accurately reflect the actual wind vibration effect of the related line of the ‘cup-type’ transmission tower in Xizang. The research in this paper provides an important solution for rational wind resistance design of ‘cup-type’ transmission towers in windy environment areas (such as Xizang) and has a good application prospect.关键词：cup-type;transmission tower;tower-line system;wind-induced vibration;wind vibration coefficient;design formula29|18|0更新时间：2025-04-26
- 摘要：Arc extinguishing gas is used widely in high voltage apparatus, and arc extinguishing performance of the gas is closely related to its recovery performance. As for the measurement of arc extinguishing performance of gas medium, there are obvious shortcomings in modeling and simulation methods and some direct or indirect methods for measuring electron density. For solving this problem, the use of Mach-Zehnder interferometry can accurately measure the electron density at each time point behind the arc, which is a key parameter for studying the recovery characteristics of gas medium. At the same time, considering the high cost of the new gas medium measurement under the circuit breaker structure, a laser induced plasma based gas medium recovery characteristics measurement experiment is designed in this paper. Through this experiment, the electron density attenuation characteristics of SF6, CO2 and N2 are measured, the characteristic value of decay rate of electron density is SF6(1)>CO2(0.77)>N2 (0.72), and the feasibility of the proposed method is verified by comparing with the existing conclusion.关键词：laser-induced plasma;Mach-Zehnder interferometry;electron density;recovery characteristics of gaseous medium22|15|0更新时间：2025-04-26
- 摘要：In the sliding electrical contact of pantograph-catenary system of railway electrification system, the current carrying efficiency, current carrying relative stability coefficient, wear rate and the contact resistance affected by pressure load are important parameters reflecting the pantograph catenary friction and current collection effect. Firstly, the experimental data is used, the prediction model of four parameters is obtained by optimizing the extreme learning machine with snake algorithm. On this basis, the optimal pressure load objective function is set up. As for the pressure load optimization, a reference point generation method is proposed to improve the non-dominated sorting genetic algorithm-Ⅲ. The pressure load is optimized to obtain a uniform and wide pareto solution set. The CRITIC method is used to calculate the objective weight of pareto solution set. Considering the influence of speed of train, an adaptive factor is introduced to obtain the adaptive weight. Finally, the optimal pressure load is determined by TOPSIS method of virtual worst solution so to provide theoretical basis for active control of pressure load of pantograph-catenary system.关键词：pantograph-catenary;optimal pressure load;multi-objective optimization;multi-objective decision-making17|13|0更新时间：2025-04-26
- 摘要：Grid-forming PV exhibits voltage source characteristics and is highly adaptable to the grid. In this paper, the impedance small-signal model of grid-forming photovoltaics based on DC voltage synchronisation is established, and the stability of grid-forming photovoltaics is investigated by impedance analysis. On the basis of stability analysis this paper proposes an optimal control strategy for the stability of grid-forming PV based on DC voltage feed forward, and comparatively analyses the stability of the improved grid-forming PV. Finally, this paper verifies the effectiveness of the control strategy proposed in this paper and the correctness of the theoretical analysis through controller hardware-in-the-loop experiments.关键词：grid-forming PV;impedance;stability;DC voltage feed forward;optimise21|16|0更新时间：2025-04-26
- 摘要：Converter valve is the core equipment of offshore VSC-HVDC system. For studying the fatigue characteristics of a supported offshore converter valve tower in operation, a finite element model is set up based on an offshore VSC-HVDC converter valve in a project. The fatigue characteristics and fatigue damage under environmental load are studied through equivalent damage and load effect analysis. According to the fatigue analysis theory, the equivalent damage value and load effect ratio of the converter valve tower are analyzed. The results show that each part of the converter valve tower has a large safety margin under the service life, and the fatigue life of the converter valve tower meets the 25 years service life requirement.关键词：offshore VSC-HVDC converter valve tower;finite element;fatigue;equivalent damage;load effect;life27|14|0更新时间：2025-04-26
- 摘要：In this paper, the adoption of phase selection closing measures are described in order to prevent the failure of power supply due to excitation inrush current of transformer during the completion of the power supply of offshore VSC-HVDC system. For assuring the smooth implementation of phase selection operation, the maximum allowable deviation of operation time permitted by the circuit breaker is determined by the simulation calculation of excitation inrush current of transformer. Through the test verification, the factors and ranges affecting the operation time dispersion of circuit breaker are confirmed. According to the above calculation and verification results and the idle time dispersion test of the circuit breaker, the intermediate value of multiple making time is selected as the final parameter, the influence of mechanical and electrical dispersion of circuit breaker is reduced, the excitation inrush current of transformer is effectively suppressed in the actual operation assessment. It can provide reference for the coordination and control strategy of the offshore VSC-HVDC phase selection closing device, operation characteristics of circuit breaker and excitation inrush current of transformer of subsequent offshore VSC-HVDC system.关键词：VSC-HVDC transmission;inrush current calculation of transformer;operation time of circuit breaker;phase selection closing32|15|0更新时间：2025-04-26
- 摘要：With the continuous development of HVDC power transmission technology, the AC and DC hybrid systems based on underground pipe corridors have been widely used. On the one hand, the operation scale of of the smart grid is expanded and, on the other hand, higher requirements are also raised for the monitoring of reliability of the equipment in the pipe gallery. In view of the issues of harsh operating environment in the pipe corridor of the AC/DC hybrid system and likely occurrence of serious safety accident, the multi-source information fusion monitoring system for the state monitoring and operation assessment in pipe corridor of AC/DC hybrid system is set up in this paper, the multi-source parameters of the import position of the AC/DC hybrid system in the pipe corridor is subjected to the digitization and intelligent treatment, the key information is extracted and the the operation state of the system is analyzed and assessed on the basis of the multi-source information fusion algorithm. The monitoring system, in case of abnormal operation of the AC/DC hybrid system in the pipe corridor, can be able to achieve fast response so as to assure the long-term and stable operation of the AC/DC hybrid system in the pipe corridor.关键词：equipment monitoring;mesh network;multi-source information fusion;fuzzy control20|15|0更新时间：2025-04-26
Research & Analysis
- 摘要：Partial discharge detection technology is one of the effective means of insulation detection of switchgear cabinet. In this paper, an insulation defect of 35 kV switchgear cabinet is detected by using such methods as transient earth voltage (TEV), air ultrasonic wave, ultra-high frequency (UHF) and infrared thermal imaging. The surface discharge at multiple places inside the busbar compartment of the switchgear cabinet is judged in combination with its discharge pattern and characteristic. It is found through power off and disassembly of the switchgear cabinet that the heat-dissipating wire mesh on the top of the cabinet is severely corroded due to the salt mist. And the rust and salinity attached to the surface of the insulating part cause a serious reduction of insulation level of the busbar. For preventing the occurrence of similar defects, it is suggested that the indoor environmental conditions of the high-voltage room of substations located in the coastal areas need to be strictly controlled, and partial discharge detection shall be performed regularly. In the design stage of the switchgear cabinet, the salt mist corrosion resistance performance shall be strengthened, and the straight-through air ducts on the top of the cabinet shall be strictly prohibited.关键词：switchgear cabinet;surface discharge;partial discharge;insulation defect;pattern;salt mist44|34|0更新时间：2025-04-26
- 摘要：High voltage disconnector is widely used in substation, and its operation status has a great impact on safe and stable operation of power grid. However, it is likely to occur various mechanical defects due to long term exposure to the outdoor environment. In this paper, a kind of mechanical fault detection technology of disconnector based on output power of motor is proposed. The input power of the motor is obtained by detecting the voltage and current of the motor during the operation of the disconnector. The output power of the motor is obtained by subtracting the power loss during internal transmission of the motor, which can effectively avoid the influence of the motor power loss on the test results. The typical waveform of four kinds of disconnectors at 110 kV and above, which are commonly used in power system, are analyzed to confirm the positions of waveform peaks and troughs and corresponding mechanical states of each section, provide guidance for subsequent mechanical fault diagnosis and its effectiveness is verified by field test.关键词：disconnector;mechanical fault;output power;motor power loss29|23|0更新时间：2025-04-26
- 摘要：Spiral spring contact finger is one of the key parts of high voltage switchgear and plays a crucial role in the performance of high voltage switchgear. In view of such bottleneck as high conductivity but low strength and hardness performance of existing brand of Cr-Zr-Cu spring contact finger, a kind of new-type Cr-Zr-Cu spiral spring contact finger with fiber reinforced high strength and high conductivity is produced by designing Cr-Zr-Cu alloy formula with high Cr content (10%-18%), combining with in-situ generation fiber technology and using such multiple material reinforcement modes as deformation strengthening, solid-solution strengthening and interface strengthening. The result shows that the tensile strength, conductivity and micro vickers hardness of the new-type Cr-Zr-Cu spring contact finger reach 791 MPa, 89.7%IACS and 192HV0.1 respectively, reach good coordination of both mechanical and electrical performance and each performance data is superior to existing brand of Cr-Zr-Cu spring contact finger (C18150).关键词：high Cr content Cr-Zr-Cu;fiber reinforcement;high strength;high conductivity;spring contact finger58|27|0更新时间：2025-04-26
Technical Discussion
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