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Research on Residential Peak-Valley Time-of-Use Electricity Price Scheme for in Hunan Province HUANG Minqi, DAI Dandan, ZHANG Li, LIAO Jing, PAN Xin Hunan Electric Power    2023, 43 (6): 63-67.   DOI: 10.3969/j.issn.1008-0198.2023.06.010 Abstract （322）      PDF（pc） （4115KB）（23）       Knowledge map    Save Aiming at the problem of power grid consumption structure in Hunan Province, the strategy of residential time-of-use electricity price scheme is proposed. Based on the residential electricity load data, the hierarchical clustering method is applied to divide the peak and valley periods of residents. Based on the heterogeneity of residential electricity demand, a demand price elasticity model is constructed, and on the basis of the current residential tiered electricity price policy, and with the goal of peak shaving and valley filling, a peak-valley time-of-use electricity price scheme for residents in Hunan Province is formulated. Reference | Related Articles | Metrics

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Review of Key Technologies in New Power System Based on Artificial Intelligence Empowerment DUAN Junfeng, LI Chenkun, YAO Wenxuan, GUO Siyuan Hunan Electric Power    2024, 44 (1): 1-10.   DOI: 10.3969/j.issn.1008-0198.2024.01.001 Abstract （239）      PDF（pc） （5512KB）（412）       Knowledge map    Save Based on the important role of artificial intelligence technology in promoting the intelligence of new power systems, this paper summarizes the current application status, technical challenges, and future development directions of artificial intelligence in new power systems. Firstly,the paper introduce the characteristics and requirements of the new power system. Then, the paper discusses the key application areas of artificial intelligence in new power systems, including the security, stability and control of large power grids, integrated collaborative analysis of source network, load storage, intelligent operation, inspection and management of power systems, as well as active distribution networks and microgrids. Finally, the paper analyzes the technical challenges faced by artificial intelligence in the new power system and proposes relevant suggestions. Reference | Related Articles | Metrics

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Transformer Fault Diagnosis Method of Optimized Hybrid Kernel Extreme Learning Machine Based on Improved Northern Goshawk Optimization Algorithm WANG Shibin, LI Duo, ZHAO Na, XIE Wenlong, HUANG Wei, JI Hongyu Hunan Electric Power    2023, 43 (4): 125-132.   DOI: 10.3969/j.issn.1008-0198.2023.04.019 Abstract （97）      PDF（pc） （3096KB）（88）       Knowledge map    Save To improve the accuracy of transformer fault diagnosis, a transformer fault diagnosis method of optimized hybrid kernel extreme learning machine(HKELM)based on improved northern goshawk optimization algorithm(INGO) is proposed. Firstly, the ReliefF algorithm is used to filter and reduce the dimensionality of 19 dimensional transformer fault features. Secondly, three strategies of Logistic tent chaotic mapping, Cauchy mutation operator, and nonlinear increasing weight, are introduced to improve the Northern Hawk optimization algorithm and enhance its global optimization ability. Then, the improved INGO algorithm is used to optimize the initial parameters of HKELM to improve its classification accuracy and robustness. Finally, the features optimized by ReliefF are used as input features for the model and compared with different transformer fault diagnosis models. The simulation results show that the INGO-HKELM fault diagnosis model has higher fault diagnosis accuracy compared to other models. Reference | Related Articles | Metrics

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Review of Digital Real Time Hardware-in-Loop Simulation for New Type Power Systems DU Shanzhou, HUANG Yongbo, LU Guoping, GAO Jin, QIN Yuxiang, LIU Yonglu, YUAN Liang Hunan Electric Power    2023, 43 (5): 3-10.   DOI: 10.3969/j.issn.1008- 0198.2023.05.001 Abstract （95）      PDF（pc） （8566KB）（105）       Knowledge map    Save With the increasing proportion of new energy access and the wide application of power electronic equipment, digital real time hardware-in-the-loop simulation has become an important means of simulation analysis of new power systems. In this context, the paper aims to summarize the research status of digital real-time hardware-in-the-loop simulation at home and abroad, and discuss the key technologies for improving simulation efficiency and accuracy as well as the difficulties in the process. This article starts from the development history of digital real-time hardware-in-the-loop simulation, and discusses the component modeling of digital real-time simulation in turn, including Ron/Roff and L/C two types of device modeling methods, summarizes three types of interface circuits of Thevenin equivalent, Norton equivalent and frequency-dependent network equivalent methods, discussed high-speed parallel algorithms, simulation platform architectures based on different computing units and types of hardware-in-the-loop simulation, introduces the basic flow of typical digital real-time hardware-in-loop simulation and its application in new power systems application examples, and finally summarizes the advantages and disadvantages of various architectures and algorithms as well as applicable scenarios. Reference | Related Articles | Metrics

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Study on Natural Convective Flow Heat Transfer in Supercritical Carbon Dioxide Cavity YE Maojing, WU Tianyu, LIU Kairui, WANG Limin, CHE Defu Hunan Electric Power    2023, 43 (4): 1-8.   DOI: 10.3969/j.issn.1008-0198.2023.04.001 Abstract （86）      PDF（pc） （4176KB）（154）       Knowledge map    Save Horizontal flow of supercritical carbon dioxide (S-CO2) will flow stratification under heating or cooling conditions, resulting in different heat transfer phenomena at the top and bottom of the tube. In order to study the flow heat transfer behavior driven by upward lift in vertical flow direction, the development process of S-CO2 natural convection and the influence of pressure, pipe diameter and temperature interval on the development process are studied based on a two-dimensional circular cavity physical model. The results show that the development process of flow heat transfer away from the pseudo-critical temperature range is relatively stable compared with the pseudo-critical temperature range. In the pseudo-critical temperature range, the higher the pressure, the faster the heat transfer development process. In the pseudo-critical temperature range, the larger the diameter of the pipe, the longer the time for heat transfer to reach stability, and the more intense the main flow zone is in the initial stage of development. Reference | Related Articles | Metrics

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Capacity Optimization Configuration of Grid-Connected Wind-Solar-Hydrogen-Storage Microgrid ZHAO Na, ZHANG Lian, WANG Shibin, LI Duo, HUANG Wei Hunan Electric Power    2023, 43 (4): 48-55.   DOI: 10.3969/j.issn.1008-0198.2023.04.007 Abstract （79）      PDF（pc） （1469KB）（163）       Knowledge map    Save A single type of energy storage device is difficult to take into account the advantages of multiple types of energy storage devices, while the hybrid energy storage system can integrate the technical and economic advantages of different types of energy storage. Aiming at the optimal configuration of hybrid energy storage based on battery and hydrogen energy storage in grid-connected mode, economic and environmental protection are taken as the objective function, the analytic hierarchy process is used to solve the multi-objective weight problem, and the particle swarm optimization algorithm is used to solve the optimal configuration of microgrid capacity. Different energy storage configuration schemes are analyzed and compared by economy and evaluation index. The results show that the cost of hybrid energy storage is 2.46% and 10.02% lower than that of single battery and hydrogen energy storage. The self-balancing rate is 7.65% and 23.89% higher than that of single battery and hydrogen energy storage, and the redundancy is 19% and 38.16% lower than that of single battery and hydrogen energy storage. Reference | Related Articles | Metrics

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On-Site Installation Method of Fault Warning Equipment for 252 kV High-Voltage Circuit Breaker HAN Chenlei, CHEN Hao, XIA Bing, ZHANG Ruowei, SUN Zichang, WANG Wei, WANG Ruihua Hunan Electric Power    2023, 43 (6): 111-115.   DOI: 10.3969/j.issn.1008-0198.2023.06.017 Abstract （78）      PDF（pc） （6858KB）（6）       Knowledge map    Save In response to the high cost and poor real-time performance of traditional power outage detection methods for the operating status of high-voltage circuit breakers, an on-site installation method for a 252kV high-voltage circuit breaker fault warning equipment is proposed to achieve real-time monitoring and fault warning of the operating status of high-voltage circuit breakers. The on-site installation practice of the 252 kV circuit breaker fault warning equipment in a 220 kV substation in Jiangsu province has verified the effectiveness and feasibility of this method. Reference | Related Articles | Metrics

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Discontinuous Modulation for a Quasi-Z-Source Inverter With Low Switching Times and High Voltage Gain YI Wenjing, CAO Kun, MENG Yuwei, LUO Zhaoxu, CHENG Zhun Hunan Electric Power    2023, 43 (5): 61-70.   DOI: 10.3969/j.issn.1008- 0198.2023.05.010 Abstract （75）      PDF（pc） （16347KB）（49）       Knowledge map    Save The quasi-Z-source inverter is widely used to replace traditional two-stage structures due to its advantages of continuous input current and simple structure. Aiming at the problems of complex gate signals generation, excessive switching times of inverter switches, high switching losses, and insufficient voltage gain in the existing modulation strategies, a discontinuous modulation for quasi-Z-source inverter with low switching times and high voltage gain is proposed, which uses fewer reference signals to generate gate signals. At the same time, the switching signals of this discontinuous modulation strategy are clamped to positive or negative pole, which significantly reduces the switching times of the inverter, thereby reducing the switching losses of the switches. In addition, the shoot-through duration and the insertion position are reasonably planned to achieve the greatest voltage gain. The correctness and effectiveness of the modulation strategy are verified by MATLAB/PLECS simulation analysis and RT-LAB experimental results. Reference | Related Articles | Metrics

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Case Analysis and Application of Waste Oil Disposal in Transformer REN Qiaolin, ZHANG Yi, ZHANG Wei, CAI Xuan, WU You, LI Zhongling Hunan Electric Power    2023, 43 (4): 114-117.   DOI: 10.3969/j.issn.1008-0198.2023.04.017 Abstract （73）      PDF（pc） （1358KB）（56）       Knowledge map    Save Taking the waste oil treatment of a power supply company as an example, the Meyers index classification and differentiation treatment of oil products are introduced, it not only reduces environmental pollution, but also extends the life cycle of transformer oil, saves the cost of oil treatment and new oil purchase, and promotes the utilization of renewable resources. Reference | Related Articles | Metrics

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Research on Dual Active Bridge Converter and It's Hybrid Modulation for New-Generation Power Systems ZHANG Yiming, XIE Ronghuan, CHEN Xiaoying Hunan Electric Power    2023, 43 (5): 16-22.   DOI: 10.3969/j.issn.1008- 0198.2023.05.003 Abstract （70）      PDF（pc） （16472KB）（81）       Knowledge map    Save The new-generation power systems mainly relies on a high proportion of new energy grid connection. DC transformers is an important energy management unit in new-generation power systems, need to have higher performance and conversion efficiency. In order to reduce current effective value of the DC transformer and improve the control flexibility, this paper proposes a combined dual active bridge converter based on modulated coupled inductor. The proposed converter controls the equivalent inductance of the modulated coupled inductor by modulating pulse-width-modulation signals, without any additional auxiliary circuits. In order to reduce the current effective value of the converter, when the converter operates at light load and the voltage does not match, the coupled inductor can be modulated and controlled to a larger equivalent inductance. When the converter operates at heavy load, the coupled inductor can be modulated and controlled to a smaller equivalent inductance. Meanwhile, a hybrid modulation strategy for the converter is proposed based on the working principle of the modulated coupled inductor, and a minimum current compliance control law is designed. Finally, the proposed converter is validated through experiments, and the results show the effectiveness of the proposed method. Reference | Related Articles | Metrics

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Mechanism and Hierarchical Coordinated Control of Solar Photovoltaic Inverter Cluster Resonance in Civil Buildings DING Jinsong, YAO Hongde, LI Shengqing, MENG Huanping, ZHU Hui Hunan Electric Power    2023, 43 (4): 32-39.   DOI: 10.3969/j.issn.1008-0198.2023.04.005 Abstract （68）      PDF（pc） （14816KB）（34）       Knowledge map    Save The clustering of photovoltaic(PV) inverter in residential buildings is prone to harmonic resonance, which seriously affects system stability and power quality. To address this problem, a mathematical model of PV inverter clusters connected to the grid is established, the resonance mechanism and resonance characteristics of single inverters and inverter clusters are derived, and a hierarchical coordination control strategy for PV inverter cluster resonance is proposed. In the first layer, for the inherent resonance of LCL-type PV inverters, an active damping method based on capacitor-voltage inertia feedback with forward-channel series trap is proposed.In the second layer, for the resonance generated by the coupling of PV inverter clusters with grid impedance,a method for suppressing the resonance of parallel virtual admittance of common coupling points is proposed.The grid-connected current quality is improved through the hierarchical division and coordinated control of the grid-connected resonance of inverter clusters.The simulation results show that compared with the traditional capacitor current feedback strategy, the harmonic distortion rate of grid-connected current decreases obviously, and the grid-connected resonant of the inverter is effectively suppressed, which proves the feasibility of the proposed strategy. Reference | Related Articles | Metrics

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Research on Distortion Correction Method of Aerial Photovoltaic Module Images WANG Jiawen, ZHU Yongcan, WANG Shuai, LI Kefeng Hunan Electric Power    2023, 43 (4): 74-79.   DOI: 10.3969/j.issn.1008-0198.2023.04.010 Abstract （67）      PDF（pc） （3609KB）（68）       Knowledge map    Save Aerial photography of photovoltaic components often suffers from distortion due to shooting angle issues, which affects the measurement, recognition, and classification of elements like straight lines, angles, and proportions. To address this problem, this paper proposes an undistorted aerial photovoltaic component image correction method that requires no calibration. The approach first extracts four critical feature points from the photovoltaic component image using a feature point extraction algorithm and then matches them using a feature point matching algorithm to obtain their corresponding relationships before and after distortion. Secondly, the theoretical principles of computational geometry are utilized to compute the parameters T necessary for distortion correction through triangulation and coordinate transformation of the corresponding points. Finally, distortion correction is carried out on the image using parameter T to obtain the corrected photovoltaic component image. This algorithm not only improves the visual correction effect of the image but also increases the accuracy of data by 20%~55%.This method has a high application value in the foreign object recognition, operation and maintenance of the aerial photovoltaics module image. Reference | Related Articles | Metrics

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Risk Assessment Model for Load Redistribution Attacks Based on Game Theory YU Mengxi, YAN Yu, ZHOU Zhanfan, DU Min, WANG Lianhong Hunan Electric Power    2024, 44 (2): 1-8.   DOI: 10.3969/j.issn.1008-0198.2024.02.001 Abstract （66）      PDF（pc） （6884KB）（36）       Knowledge map    Save To assess the risk of cyber-attack,this paper constructs a bilayer assessment model of load redistribution attack risk based on game theory,introduces false data attacks and load redistribution attacks,and constructs a two-layer optimisation model for the risk of load redistribution attacks based on a game-theoretic approach.In addition,this paper uses the KKT condition to transform the bilayer model into a single-level mixed-integer linear programming model,and carries out and analyzes simulation experiments on the IEEE 14-bus system and the IEEE 30-bus system,to assess the risk of load redistribution attacks on the security and economic operation of the power system. In addition,this paper provides suggestion on how to prevent and defend against load redistribution attacks. Reference | Related Articles | Metrics

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Design and Simulation of Power Supply-Traction-Hybrid Energy Storage System for Urban Rail Trains ZHU Zhiqiang, WANG Xin, QIN Bin Hunan Electric Power    2024, 44 (1): 24-31.   DOI: 10.3969/j.issn.1008-0198.2024.01.004 Abstract （65）      PDF（pc） （7016KB）（40）       Knowledge map    Save In order to further improve the recovery and utilization efficiency of urban rail train regenerative braking energy, a structure of urban rail train traction power supply system based on distributed ground hybrid energy storage is designed through the analysis of system functional requirements, and the power supply network, train traction and energy storage system models are established. Moreover, aiming at the problem that low pass filtering leads to a large amount of power exchange between lithium batteries and supercapacitors, a stepped power allocation method with supercapacitor compensation is proposed.This method has small computation and strong real-time performance,and can avoid the internal power circulation of the hybrid energy storage system. Combined with the proposed model and strategy, MATLAB Simulink is used to simulate.The results validate that the energy utilization efficiency of the hybrid energy storage system is improved by 1.39%, the voltage regulation rate is increased by 12.75% and the energy saving rate is increased by 6.72%. Reference | Related Articles | Metrics

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Research on Detection Circuit and Method of Ground Insulation Impedance for Photovoltaic Array LI Jiong, JIANG Li, NING Guangfu, WU Jinbo, HE Zhiqiang Hunan Electric Power    2023, 43 (5): 11-15.   DOI: 10.3969/j.issn.1008- 0198.2023.05.002 Abstract （64）      PDF（pc） （3919KB）（56）       Knowledge map    Save This paper proposes a detection circuit and method of insulation impedance for photovoltaic array, which contains a voltage sampling circuit of photovoltaic negative electrode to the earth, two electronic switches and three balance resistors. In order to balance the sampling resistance, a balance resistor equivalent to the resistance of the voltage sampling branch is always connected in parallel between the positive electrode of the photovoltaic panel and the earth, so that the voltage of the sampling point between the negative electrode of the photovoltaic panel and the earth will not be extremely small when the insulation performance is normal, which reduces the requirements for voltage sampling accuracy. The branch consisting of an electronic switch and a resistor in series is connected between the positive/negative electrodes of the photovoltaic panel and the earth, and the resistor in series is equivalent to the critical insulation impedance that meets the leakage current standard. When the impedance of one electrode of the photovoltaic panel decreases, the other pole electronic switch is closed connected in parallel with the other electrode, and the corresponding balance resistor is connected to improve the sensitivity of the sampling voltage to the impedance change of the circuit, so as to calculate the actual impedance of the circuit. The proposed method can obtain accurate insulation impedance with low-precision voltage sampling, which improves the reliability of detection. Reference | Related Articles | Metrics

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A New Approach Law Sliding Mode Fault Tolerant Control Method for Double Fed Induction Generator Actuator Fault LI Shengqing, WEN Yanxi, CHEN Xin Hunan Electric Power    2023, 43 (4): 9-15.   DOI: 10.3969/j.issn.1008-0198.2023.04.002 Abstract （62）      PDF（pc） （1809KB）（85）       Knowledge map    Save In order to overcome the gain-bias fault of the actuator during the operation of the double fed induction generator, a second order non-singular fast terminal sliding mode fault tolerant control is designed by combining the PID sliding surface with the nonlinear non-singular terminal sliding mode surface, and by associating the sliding mode surface function with the control gain using a new adaptive reaching law. Then Lyapunov function is used to prove the stability of the controller. The simulation and experimental results show that compared with the traditional PID and the traditional sliding mode control, the proposed control method weakens chattering, improves the response speed by 49.8%, reduces the steady-state error of the system, and has better fault tolerance. Reference | Related Articles | Metrics

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Review on Non-Contact Voltage/Electric Field Sensors KE Kun, YANG Qing, QIU Zhenhui, LIAO Wei, ZHOU Jianglin Hunan Electric Power    2023, 43 (5): 71-78.   DOI: 10.3969/j.issn.1008- 0198.2023.05.011 Abstract （61）      PDF（pc） （9478KB）（69）       Knowledge map    Save Safe and accurate acquisition of electrical parameter data of the power system can ensure the safe and stable operation of the power system. Compared with traditional voltage measurement, non-contact measurement technology has higher safety because it does not need to have a direct electrical connection with the primary equipment, and has the characteristics of small size, frequency bandwidth, and good transient response characteristics, which can meet the needs of modern power grid distributed sensor networks. This paper introduces in detail the technologies of coupling capacitive voltage sensing, voltage sensing based on current integration method, D-dot electric field sensing, electric field sensing based on electro-optical effect, piezoelectric effect, and electrostatic induction effect, analyzes the advantages and existing problems of the above sensing technology, and introduces the method of electric field inversion voltage. Finally, the development prospect of non-contact voltage/electric field sensing technology is prospected. Reference | Related Articles | Metrics

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Short-Term Load Forecasting of Long Short Term Memory Network Optimization Based on Variational Mode Decomposition- Permutation Entropy-Improved Pelican Optimization Algorithm XIE Wenlong, ZHANG Lian, WANG Shibin, LI Duo, YANG Jiahao Hunan Electric Power    2023, 43 (6): 82-92.   DOI: 10.3969/j.issn.1008-0198.2023.06.013 Abstract （60）      PDF（pc） （11823KB）（39）       Knowledge map    Save Aiming at the problems of modal decomposition aliasing and difficult selection of long short term memory network parameters in the traditional power load forecasting model, this paper proposes a new model, namely the long short-term memory network model based on variational modal decomposition and improved pelican optimization algorithm. Firstly, variational modal decomposition is used to decompose the power load data into multiple modes with low complexity, and the subseries are recombined by permutation entropy to reduce the prediction difficulty. Then, two strategies, logistic chaotic mapping, fusion Cauchy mutation and reverse learning, are introduced to improve the global optimization ability. Then, the improved pelican optimization algorithm is used to optimize the long short term memory network parameters to improve the generalization ability and practical operation of the model. Finally, the reconstituted submodes are predicted and superimposed respectively to obtain the final prediction results and compared with the prediction models of different optimization algorithms. Experimental results show that the long short term memory network model of variational mode decomposition-permutation entropy-improved pelican optimization algorithm has higher prediction accuracy and stability, and can effectively predict short-term power load. Reference | Related Articles | Metrics

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Research Progress of Green Hydrogen Preparation From Renewable Energy Electrolytic Water BO Yanjun, HE Zhoulei, YANG Jingze, LIN Ziruo, YAO Hong Hunan Electric Power    2023, 43 (6): 23-30.   DOI: 10.3969/j.issn.1008-0198.2023.06.005 Abstract （59）      PDF（pc） （9828KB）（37）       Knowledge map    Save Based on the potential role of producing green hydrogen from renewable energy electricity in peak shaving, valley filling, and power consumption, this paper introduces different types of electrolytic cell equipment, conducts research on green hydrogen production systems based on wind, solar, hydro, and geothermal energy, analyzes their application status and feasibility, and looks forward to the development direction of renewable energy electrolytic water production green hydrogen systems, providing suggestions for the development of the hydrogen energy industry. Reference | Related Articles | Metrics

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Analysis and Research on Influence of High Temperature and Dry Weather on Regional Power System in 2022 Summer BIE Fangmei, FANG Rengcun, WAN Jing, FAN Yuhong, CHEN Xi Hunan Electric Power    2023, 43 (4): 108-113.   DOI: 10.3969/j.issn.1008-0198.2023.04.016 Abstract （59）      PDF（pc） （2088KB）（108）       Knowledge map    Save In view of the difficulties and challenges faced by the power system during the extremely hot weather in summer in 2022, taking the operation of typical provincial power grids as an example, the maximum load, peak load duration and summer power grid load characteristics of the whole network are studied, and the outstanding problems in power supply during the summer vacation are analyzed, so as to put forward countermeasures and suggestions for how to ensure the safe and stable operation and reliable supply of the power system in summer. Reference | Related Articles | Metrics

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Strategy of An Improved Adaptive Sliding Mode Controlling Virtual Synchronous Generator Control Based on Direct-Driven Permanent Magnet Wind Power System CHEN Anping, HU Xiaolin, LUO Zhaoxu, CHENG Zhun Hunan Electric Power    2023, 43 (4): 63-73.   DOI: 10.3969/j.issn.1008-0198.2023.04.009 Abstract （59）      PDF（pc） （5028KB）（67）       Knowledge map    Save For the direct-drive permanent magnet synchronous wind generator system, because of the difference of equivalent output impedance between inverters and transmission line impedance, the problems of multi-inverters controlled by traditional virtual synchronous generator (VSG) , such as unequal power distribution and poor circulating current suppression are presented,and an improved adaptive sliding mode control strategy is proposed for multiple VSG power sharing and circulation suppression. The given power calculating is calculated according to the total load capacity and the capacity of each inverter, and the virtual impedance according to the given reactive power to compensate the voltage drop caused by the difference of line impedance is adjusted .The sliding mode control of two VSG is designed in coordinate system, and the sliding mode surface is designed based on the difference between the inverter output voltage and the VSG reference voltage, based on Lyapunov stability theory, an adaptive sliding mode controller is designed, which consists of equivalent control, switching control and adaptive compensation. Compared with the traditional control method, the proposed control strategy power sharing and circulation suppression are achieved , and the distribution accuracy of reactive power and VSG output voltage are improved. Finally, the correctness and validity of the control strategy are verified in MATLAB/Simulink. Reference | Related Articles | Metrics

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Image Classification Method Based on Deep Learning for Inspection Unmanned Aerial Vehiclesin Transmission Line YANG Hongzhao, XI Yanhui, XIANG Sheng, XU Zhikang Hunan Electric Power    2024, 44 (1): 53-58.   DOI: 10.3969/j.issn.1008-0198.2024.01.008 Abstract （58）      PDF（pc） （3904KB）（80）       Knowledge map    Save Due to the irregularity of point cloud data, the classification accuracy of point cloud data feature values is difficult to meet the requirements of transmission line inspection. Therefore,a lidar point cloud classification method based on graph signal processing is proposed. When processing irregular transmission line image signals, the method can directly generate feature values from the original point data, thereby improving classification accuracy. In order to validate the proposed method, the algorithm is validated through physical simulation, and the results show that the classification accuracy in the image could reach 90%. Reference | Related Articles | Metrics

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Governance Method of Power Quality in New Power Distribution Area Based on Energy Storage System LAN Zheng, YIN Rui, ZOU Bin, HE Dong Hunan Electric Power    2023, 43 (4): 56-62.   DOI: 10.3969/j.issn.1008-0198.2023.04.008 Abstract （55）      PDF（pc） （3308KB）（54）       Knowledge map    Save In the new power distribution area, due to the wide application of power electronic devices and the access of a large number of distributed energy sources, the power quality of the new power distribution area is seriously affected and the power fluctuation is caused. In order to improve the power quality and power fluctuation of the new power distribution area, a new power quality management method based on energy storage system is proposed. This method can improve the comprehensive adjusting ability of the energy storage system at the head of the area. It can not only control the current harmonics, reactive power and unbalance current of the new power distribution area, but also stabilize the active power effectively. Firstly, the structure of the new power distribution area and the topology of the energy storage system are introduced, and the mathematical model is built. Then, in the harmonic detection section of the control section, the four-wire ip-iq harmonic detection method based on moving mean filter is adopted. And in the process of energy storage power adjustment, the strategy of battery charging and discharging considering energy storage capacity is adopted. At the same time, the command current is accurately tracked by repetitive control and PI control. Finally, the simulation results show that the proposed energy storage system and its control strategy can not only effectively improve the power quality of the new power distribution area, but also smooth the active power fluctuation. Reference | Related Articles | Metrics

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Accurate Classification Method of Power Customers Based on Jieba Chinese Word Segmentation GAO Pan, LI Fei, PENG Yuanhao, ZHANG Canhui, PENG Haijun Hunan Electric Power    2023, 43 (5): 151-154.   DOI: 10.3969/j.issn.1008- 0198.2023.05.022 Abstract （52）      PDF（pc） （3356KB）（52）       Knowledge map    Save Aiming at the customer segmentation in the basic data of electric power marketing, an innovative method is proposed to achieve accurate classification of major customers based on jieba Chinese word segmentation. A self-defined dictionary containing the basic categories of customers is constructed, and jieba is used to complete the segmentation of the text data. The classification feature database is built based on the classification rules of high-frequency words and keywords in the word segmentation results. The classification feature database is used as the input of the neural network pre-training model to train the neural network model of customer classification, and the accurate classification results of power customers are finally output. This method solves the problem of unclear user category or too complicated classification method in the current power system database and provides the basis for the power company to develop differentiated customer service. Reference | Related Articles | Metrics

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Ahead Optimal Dispatch of Multi Energy Power System Considering Power Flexibility and Complementarity XIAO Bai, ZHANG Bo Hunan Electric Power    2023, 43 (4): 16-23.   DOI: 10.3969/j.issn.1008-0198.2023.04.003 Abstract （51）      PDF（pc） （3056KB）（46）       Knowledge map    Save A multi energy power system day ahead optimization scheduling method considering power flexibility and complementarity is proposed to address the volatility and intermittency of wind and photovoltaic power generation, as well as the coordinated and optimized operation of multi energy power systems. Firstly, a supply and demand model for power flexibility and complementarity is established. Then, a multi-objective coordinated hierarchical optimization scheduling model for wind power, solar power, hydroenergy, gas energy, and thermal power,energy storage storage is constructed with the optimization objectives of optimizing the economy and stability of thermal power operation, and minimizing the total pollutant emissions. Renewable energy complementary power sources and complementary power demand indicators are defined, and the aggregation ratio of renewable energy complementary power sources is determined to minimize the complementary power demand indicators. Finally, the artificial bee colony algorithm is improved by introducing dynamic probability and developing the optimal guidance strategy for the bee colony, and the improved artificial bee colony algorithm is used to solve the established optimization scheduling model. The numerical results show that the proposed model and algorithm are feasible for the multi energy complementary coordinated scheduling problem. Reference | Related Articles | Metrics

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Hunan Electric Power    2023, 43 (5): 1-2.   Abstract （50）      PDF（pc） （1436KB）（50）       Knowledge map    Save Related Articles | Metrics

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A Condition Estimation Method for DC-link Capacitors Based on Pre-charging Model TIAN Rui, LIU Weike, WU Xun Hunan Electric Power    2023, 43 (4): 133-138.   DOI: 10.3969/j.issn.1008-0198.2023.04.020 Abstract （49）      PDF（pc） （2074KB）（72）       Knowledge map    Save DC-link capacitors are key components for energy buffering in converter systems and are widely used in fields such as locomotive traction, aerospace, wind power generation and photovoltaic power generation. In harsh working environments, the performance of DC-link capacitors deteriorates, the failure rate increases, and they are easily damaged. Currently, the existing methods for state identifying of capacitors are easily affected by sensor measurement noise, resulting in a significant difference between the capacitance identification results and the actual values. To solve these problems, this paper proposes a capacitor state identification method based on the pre-charging process. By constructing the pre-charging model, the mapping relationship between capacitance and voltage signal is obtained, and the influence of measurement noise is minimized. Then, the recursive auxiliary variable least square method is used to estimate the parameters of the pre-charging model, so as to obtain the accurate capacitor capacity identification results. The verification results show that this method can effectively resist the interference of measurement noise, and has good identification effect when the signal sampling frequency is greater than 500 Hz. The capacitance identification error is 0.569% when the sampling frequency reaches 1 kHz. Reference | Related Articles | Metrics

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Load Aggregator Strategic Quotation and Peak Market Clearing Optimization Considering Adjustment Cost ZHANG Lingqiao, ZHOU Zhengcheng, SHEN Shasha, XIANG Yunkun, LIU Hanlin, WANG Wei, MENG Ke Hunan Electric Power    2023, 43 (4): 24-31.   DOI: 10.3969/j.issn.1008-0198.2023.04.004 Abstract （49）      PDF（pc） （2676KB）（98）       Knowledge map    Save The access of high proportion of new energy makes the uncertainty of power supply increasing, the unbalance of power supply outstanding and the difference between peak and valley of load increasing. In order to solve the problem of unbalance of power supply and demand during peak hours, a strategic bidding strategy of load aggregator considering adjusting cost and its optimal clearing strategy in peak market are proposed. Firstly, the load aggregator is defined, and the flexible resource is classified according to the characteristics of voltage level, load curve, unit power regulation cost and power consumption characteristics. Secondly,the paper analyzes the characteristics and adjustment potential of various kinds of end-user load, establishes the model of load adjustment cost of various kinds of end-users, and constructs the strategic quotation model, to minimize the sum of load adjustment costs of load aggregators, a clearing model is established. Finally, a typical peak demand response scenario involving a regional load aggregator is taken as an example to demonstrate the validity and scientificity of the proposed method. Reference | Related Articles | Metrics

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Research on Multi-Objective Optimal Control of Virual Synchronous Generator Inverter in Unbalanced Power Grid Based on Wolf Pack Algorithm ZHU Hongping, ZHU Hongzhi, QIAN Wanming, GUO Liwen, HAN Yinglong Hunan Electric Power    2023, 43 (4): 40-47.   DOI: 10.3969/j.issn.1008-0198.2023.04.006 Abstract （49）      PDF（pc） （3980KB）（45）       Knowledge map    Save This paper presents a multi-objective coordinated optimal control of virtual synchronous generator(VSG)inverter based on wolf swarn algorithm to address the issues of unbalanced grid connected output current and fluctuations in active and reactive power when the grid voltage is unbalanced.For the current balance, suppression of active and reactive power fluctuations between the contradictions,a multi-objective optimization control is designed, introducing adjustment coefficients and imbalance, and establishing a unified expression for negative sequence reference current and a multi-objective optimization function. And through the wolf swarm algorithm, the multi-objective function is optimized to achieve coordinated control among the three controls, improving the output power quality of the VSG inverter. Finally, the proposed control method is simulated to verify its feasibility and effectiveness. Reference | Related Articles | Metrics

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Research on Grounding Grid Corrosion Diagnosis Based on Electromagnetic Field Theory and Earth Surface Potential CHU Xu, YU Shaoshuai, YAN Yabing, LI Hui Hunan Electric Power    2023, 43 (4): 118-124.   DOI: 10.3969/j.issn.1008-0198.2023.04.018 Abstract （49）      PDF（pc） （6036KB）（64）       Knowledge map    Save Because of its large scale, complex structure and strong electromagnetic interference, the grounding grid of the substation has the problems of difficult detection and large error in corrosion diagnosis. Aiming at these problems,this article proposes a method based on the combination of electromagnetic field theory (EFT) and earth surface potential (ESP) to diagnose the corrosion conductor of grounding grid,so as to make up for the defect of poor measurement accuracy of EFT method under strong magnetic interference. This method first analyzes the magnetic induction intensity distribution of the corroded conductor on the basis of EFT. Then the paper analyzes the ESP distribution of the corroded conductor, combines the magnetic induction intensity curve with the ESP distribution curve, and finally determines the location and type of conductor corrosion. The test shows that the position of the corroded conductor obtained by this method is consistent with the position of the set corroded conductor, which shows the accuracy of the method in diagnosing the corroded conductor. Reference | Related Articles | Metrics

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Finite Element Simulation of Abrasive Wear Characteristics for a Ring Chain Line Fitting ZENG Ping, LIU Zhigang, HUANG Changyong, LUO Fangxu, ZHANG Huapeng, CAI Xinjing Hunan Electric Power    2023, 43 (4): 90-94.   DOI: 10.3969/j.issn.1008-0198.2023.04.013 Abstract （48）      PDF（pc） （2927KB）（60）       Knowledge map    Save Electric power fittings located in the strong wind area are prone to abrasive wear. In order to study abrasive wear mechanism of electric power fittings, the wear process of a ring chain line fitting is simulated based on the finite element method. It is indicated that the maximum stress of the U-shaped ring is 692.2 MPa, far exceeding the yield strength of 45# steel which is equal to 355 MPa. After 1 400 times of abrasive wear, a negative strain along the Z-axis is shown on the contact area of the U-shaped ring, and plastic deformation outward in both the X and Y directions is observed. The wear rate of U-shaped ring makes a cycle that repeats itself from large to small and then from small to large. Reference | Related Articles | Metrics

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Study on Lightning Damage Characteristics of Wind Turbine Blades Under Metal Mesh Protection JIANG Lingfeng, JIANG Zhenglong, XIE Pengkang, FU Zhiyao, HUANG Xiaoqi Hunan Electric Power    2023, 43 (6): 6-10.   DOI: 10.3969/j.issn.1008-0198.2023.06.002 Abstract （48）      PDF（pc） （5506KB）（37）       Knowledge map    Save Lightning damage of wind turbine blades is a difficult problem in the actual operation of wind power system. Metal mesh can be used as a supplementary method for lightning protection of blades. However, the lightning process and damage mechanism of high-amplitude lightning current after the blade is laid with metal mesh are not clear. In order to study the lightning protection method of wind turbine blade metal mesh and the lightning damage characteristics of blade composite materials, a test platform for lightning large current flashover of real wind turbine blades is built. Through the leader attachment test, the potential lightning strike position of the wind turbine blade is determined, and the direct damage effect of the lightning introduction point is observed synchronously. The test results show that the amount of lightning transfer charge and the flow capacity of the down lead are important factors for whether the blade is damaged by lightning. The pressure plate between the blade tip and the blade body has the risk of structural tearing. The type design of the discharge channel of metal mesh and the pressure plate should be optimized to improve the reliability of the blade′s lightning high current tolerance. The research results reveal the characteristics of large current damage of wind turbine blades under the lightning protection method of metal mesh, and guide its lightning protection design. Reference | Related Articles | Metrics

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Fault Diagnosis of High Voltage Circuit Breakers Based on Support Vector Machine of Improverd Sand Cat Swarm Optimization Algorithm HUANG Wei, ZHANG Lian, WANG Shibin, ZHAO Na, JI Hongyu Hunan Electric Power    2024, 44 (1): 128-135.   DOI: 10.3969/j.issn.1008-0198.2024.01.018 Abstract （48）      PDF（pc） （3577KB）（40）       Knowledge map    Save In order to analyze and diagnose the status of high-voltage circuit breakers more accurately, a multi-strategy improved sand cat swarm optimization (ISCSO) algorithm is proposed to optimize the fault diagnosis method of support vector machine (SVM). Firstly, sand cat swarm optimization(SCSO) algorithm is improved through various improvement strategies to enhance the algorithm's global search ability, local search ability, and global balance ability. Two different types of test functions are used to test the performance of ISCSO, verifying its stronger convergence and optimization ability. Then, ISCSO is used to optimize SVM and establish a fault diagnosis model. Next,complete ensemble empirical mode decompasition with adaptive noise energy entropy is used to extract features from vibration signals and construct a feature sample set. Finally, the extracted feature sample set is input into the ISCSO-SVM model for fault diagnosis of high-voltage circuit breakers. The experimental results show that the diagnostic accuracy of this method reaches 96.29%. Compared with the other three models, it has been proven that this method has higher accuracy, and better stability. Reference | Related Articles | Metrics

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Research on Breaking Small Capacitive Current of Circuit Breaker Used in Ultra High Voltage Direct Current XU Meng, CHEN Yu, GAO Yang, SHEN Fenghui Hunan Electric Power    2023, 43 (6): 144-150.   DOI: 10.3969/j.issn.1008-0198.2023.06.022 Abstract （47）      PDF（pc） （9099KB）（35）       Knowledge map    Save In order to ensure that the type test of breaking small capacitive current of 800 kV AC SF6 ciruit breaker in UHVDC transmission system of ±800 kV and ±1 100 kV is successfully passed and the products run reliably for a long time after being put into operation, the electric field strength and gas density of the circuit breaker under different conditions are calculated by finite element method, and it is concluded that the dielectric strength of the original circuit breaker and three optimized schemes and the position of the lowest point of dielectric strength during the circuit breaker opening process are not affected by the opening speed and inflation pressure. Under the optimized scheme, the average opening speed of the circuit breaker is increased by 5.7%, which can meet the dielectric strength requirement that the peak recovery voltage reaches 2 100 kV. The test passed smoothly, and there was no re-breakdown in the breaking process, which proved that the calculation method and optimization scheme adopted had practical guiding significance. Reference | Related Articles | Metrics

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Multi-Sources Coordinated Dispatch for Multi-Time Scale Isolated Grid Based on Model Predictive Control DU Shanzhou, HUANG Yongbo, JIAN Yunfeng, XU Jing, SONG Xiaoyu, YUAN Liang Hunan Electric Power    2023, 43 (5): 23-30.   DOI: 10.3969/j.issn.1008- 0198.2023.05.004 Abstract （47）      PDF（pc） （9804KB）（38）       Knowledge map    Save With the development of renewable energy and energy storage technology, there are heterogeneous power sources of multiple energy in the isolated power grid. The randomness and fluctuation of renewable energy bring great challenges to the safe and economic operation of the system. Aiming at the coordinated control of the sources in the isolated power grid, a multi-time scale collaborative optimization strategy of multi-source for isolated power grids based on model predictive control is proposed. A multi-time scale dispatch model of day-ahead, intra-day, real time is constructed to achieve forward-looking and step-by-step regulation of the sources in the isolated grid. A hybrid particle swarm optimization algorithm is used to solve the problem containing continuous variables and binary variables. The proposed model is applied to two isolated systems, through which the feasibility and effectiveness of the proposed method on ensuring the safe and economic operation of the system are proved. Reference | Related Articles | Metrics

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Impedance-Emulating Control Strategy for Series-Compensated Three-Phase Grid-Connected Inverters DENG Zini, SU Mei,SUN Yao, LIN Jianheng Hunan Electric Power    2023, 43 (5): 31-37.   DOI: 10.3969/j.issn.1008- 0198.2023.05.005 Abstract （46）      PDF（pc） （14840KB）（31）       Knowledge map    Save To increase the long-distance power transmission capacity of renewable energy power stations, series compensation is a common solution. However, oscillation problems are introduced by the interaction between grid-connected inverter and series-compensated power lines, threatening the safe operation of the power system. To address this challenge, an extended impedance-emulating control strategy without the phase-locked loop is proposed,and the proposed method can stabilize the system in weak grids and high series compensation level grids. Besides, the effectiveness of the method is verified by stability analysis. Eigenvalues analysis is performed to guide parameter design. Finally, theoretical analysis and proposed control strategy are validated with simulation and experimental results. Reference | Related Articles | Metrics

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Research on Coordination and Optimization of Large Scale Electric Vehicles Connected to Microgrid Using Improved Symbiotic Organisms Search Algorithm KANG Tong, ZHU Jiran, TANG Haiguo, ZHOU Hengyi, ZHOU Kehui Hunan Electric Power    2023, 43 (5): 144-150.   DOI: 10.3969/j.issn.1008- 0198.2023.05.21 Abstract （46）      PDF（pc） （6636KB）（40）       Knowledge map    Save Aiming at the optimization and coordination operation of electric vehicles connected to microgrid, the architecture, operation mode, output characteristics and mathematical model of microgrid including electric vehicles are analyzed , and the disorderly charging load model of electric vehicles is established by using Monte Carlo method. An objective function is established to minimize the comprehensive cost and peak-valley difference of microgrid. To solve the complex, high-dimensional and model and enhance the performance of original symbiotic organisms search algorithm(SOS), a novel improved symbiotic organisms search algorithm algorithm(ImSOS)is proposed. In ImSOS, a quasi-reflection-based learning scheme is employed in the population initialization step of original SOS. Moreover, the strategy of the modifications of benefit factors is used in the mutualism phase of SOS. A strategy of narrowing the search range of randomly generated coefficients is adopted in the commensalism phase of SOS. Finally, by setting up scenarios of disordered charging and coordinated optimized operation of electric vehicles, the output comprehensive operating cost and peak-valley difference in microgrid are compared. The result presents the scientificity and effectiveness of the method proposed in this paper. Reference | Related Articles | Metrics

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Application Scheme of Transformer Water Spray Fire Extinguishing Systems Adding Extinguishing Agent CHEN Baohui, LIU Yu, ZHOU Tiannian, WU Chuanping, LI Bo Hunan Electric Power    2023, 43 (6): 1-5.   DOI: 10.3969/j.issn.1008-0198.2023.06.001 Abstract （45）      PDF（pc） （11866KB）（37）       Knowledge map    Save In view of the problems existing in the transformer water spray fire extinguishing system, the transformer water spray fire extinguishing system with fire extinguishing agent and the fire and explosion prevention capacity improvement scheme of the fire pipe network are proposed, and the application technology are expounded. A fire extinguishing test platform using a real 110 kV transformer model is built to study the influence of extinguishing agent on extinguishing transformer oil fire by water spray fire protection system. The results show that the pure water spray is difficult to extinguish the transformer oil fire in the area where the water spray is not directly injected or semi-covered. After adding fire extinguishing agent, simulated transformer fire can be extinguished within 42 s. After 16.7% of the sprayers are damaged, the water spray system with extinguishing agent could still extinguish the fire efficiently within 40 s. The test results provide reference for the construction of transformer water spray fire protection system. Reference | Related Articles | Metrics

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Maximum Power Tracking of Wind Power Generation System Based on Improved Nonsingular Fast Terminal Sliding Mode Inversion Control LI Shengqing, CHEN Xin, WEN Yanxi, YAO Hongde, DENG Na Hunan Electric Power    2023, 43 (5): 109-115.   DOI: 10.3969/j.issn.1008- 0198.2023.05.016 Abstract （45）      PDF（pc） （6582KB）（50）       Knowledge map    Save To address the problems of non-linearity, uncertainty of system parameters and external disturbances in maximum power tracking of permanent magnet direct-drive wind turbine systems,a non-singular fast terminal sliding mode inversion control strategy based on a finite-time disturbance observer is proposed. For the speed tracking problem, the system parameter uncertainty and external disturbances are defined as set-total disturbances, which are compensated after fast and accurate estimation by the observer. The inverse control method is used to deal with the nonlinear system, and the virtual control law is designed in combination with the dynamic surface control, while the sliding mode control law is designed to improve the convergence speed and tracking accuracy of the system. The stability and effectiveness of the system are demonstrated by Lyapunov theory and simulation experiments. Reference | Related Articles | Metrics

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An Isolated SWISS Rectifier with Low Voltage Stress ZHOU Wanchuan, ZHANG Xu, LUO Zhaoxu, CHENG Zhun Hunan Electric Power    2023, 43 (5): 99-108.   DOI: 10.3969/j.issn.1008- 0198.2023.05.015 Abstract （44）      PDF（pc） （19057KB）（23）       Knowledge map    Save In order to solve the problems of high voltage stress in high-frequency switching tubes of SWISS-forward rectifier and the straight-through risk of SWISS phase-shift full-bridge rectifier, a dual-transistor forward SWISS rectifier topology is proposed in this paper. The fusion of the dual-transistor forward converter and SWISS rectifier not only provides direct galvanic isolation for the SWISS rectifier but also reduces the voltage stress of the high-frequency switching transistor. At the same time, each bridge arm of the output circuit is composed of a diode and a switch in series, which ensures the reliability of the rectifier. The working principle of the dual-transistor forward SWISS rectifier and the voltage stress of the switching tube are analyzed in detail, and a two-stage filter is designed to suppress the current oscillation in order to solve the problem of input current distortion at the sector boundary. Finally, the feasibility of the rectifier topology and the effectiveness of the control method are verified on the simulation platform. Reference | Related Articles | Metrics