- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Detection of Volatile Organic Compounds in Exhaled Human Breath by Millimeter- Wave/Terahertz spectroscopy
摘要： Conventional practice for transformer dissolved gas analysis (DGA) is to use concentrations of several fault gases, with or without total dissolved combustible gas, for evaluating apparent fault severity. We suggest a simpler approach based on the normalized energy intensity (NEI), a quantity related directly to fault energy dissipated within the transformer. DGA fault severity scoring based on NEI is shown to be sensitive to all IEC fault types and to be more responsive to shifts in the relative concentrations of the fault gases than scoring based on fault gas concentrations. Instead of eight or more gas concentration limits, NEI scoring requires only two or three limits that can be empirically derived to suit local requirements for any population of mineral-oil-filled power transformers.
关键词： enthalpy,Dissolved gas analysis (DGA),normalized energy intensity (NEI),fault energy,transformer,fault severity
更新于2025-09-16 10:30:52
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An isolated single-switch high step-up DC/DC converter with three-winding transformer for solar photovoltaic applications
摘要： An isolated single-switch high step-up DC/DC converter for solar photovoltaic applications is presented in this paper. The proposed isolated converter consists of a single switch, two voltage doubler circuits and a three-winding transformer. The four capacitors in the voltage doubler circuits are charged in parallel and are discharged in series by the secondary and tertiary winding of the three-winding transformer to attain a high step-up voltage gain. In addition, the voltage doubler circuits absorb energy in parallel, which, in turn, signi?cantly alleviates the voltage stress on the switch with low turns ratio and low duty cycle. The converter operation principle and steady-state analysis of the isolated high gain converter for continuous conduction mode are presented in detail. Laboratory tests and simulation using MATLAB/Simulink are carried out with a prototype of 80 W converter. The predicted and test results establish a close agreement between the validity of the analysis and the viability of the proposed circuit.
关键词： Voltage doubler circuit,Single-switch isolated converter,Three-winding transformer,High-voltage gain
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Design of Loosely Coupled Transformer of Wireless Power Transfer for Higher Misalignment Tolerance of System Efficiency
摘要： The offset between the primary and secondary couplers of the Loose-Coupled Transformer (LCT) results in deviation in the efficiency of the wireless transmission system. In order to obtain higher efficiency deviation tolerances, a three-loop LCT structure is proposed. The LCT's intermediate couplers are slightly larger than primary and secondary couplers. A 30mm air gap between primary and intermediate couplers exists. The compensation capacitance of the proposed intermediate coupler is variable. Moreover, when the horizontal or vertical offset between the primary and secondary couplers reaches 200 mm or 50 mm, respectively, the intermediate couplers can move with the secondary couplers. At the same time, the proposed LCT control strategy is optimized. A 3-kW prototype was developed for experimental verification, which proved the effectiveness of proposed LCT and control strategy.
关键词： misalignment tolerance of efficiency,moveable intermediate coil,variable compensate capacitor,loosely coupled transformer (LCT),Wireless power transfer (WPT)
更新于2025-09-12 10:27:22
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Coordinated optimal dispatch of photovoltaic units with updated power electronic transformer
摘要： The stochastic variation of photovoltaic (PV) generation units in the distribution grid has increased complexity of the optimal dispatch. Updated power electronics devices such as power electronics transformer (PET) are installed to improve the energy efficiency of DC power appliances and the control flexibility. The synergy effects of optimal dispatch of photovoltaic units and updated PET operation are analyzed in this paper. A two-stage optimization model is established to search for the best configuration and operation of distribution grid with updated PET feeders and photovoltaic inverters. The optimal configuration of PETs is given in the upper stage and given to the lower stage as input parameters to regulate the active and reactive power of photovoltaic inverters associated with operation of feeders updated with PETs. The coordinated optimization between updated PETs and photovoltaic generation units is developed to minimize the operation cost and total power losses in the distribution grid. NSGA-II algorithm is adopted to solve the proposed multi-objective optimization with constraints from both reliable operation of power system and power electronics devices. Comparisons between the simulation results with and without the proposed coordinated optimization for PETs and PVs valid the effectiveness of two-stage optimization model. The operation cost and power losses are reduced while avoiding the power curtailment of PV units by optimally configuring and regulating the power electronic devices including the PETs and inverters of PVs in the test distribution network.
关键词： multi-objective optimization,integration of photovoltaic generation,power electronic transformer,coordinated optimal dispatch
更新于2025-09-12 10:27:22
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A High Sensitivity Optical Fiber Interferometer Sensor for Acoustic Emission Detection of Partial Discharge in Power Transformer
摘要： We propose a Michelson ultrasonic sensing system for detecting the acoustic emission generated by the partial discharge in power transformer. In order to guide the sensor head design in the sensing system for high sensitivity, a theoretical model is established to investigate the effects of the sensor head dimensions on the response sensitivity. After that, an optimized sensor head is designed. In the frequency range from 80 kHz to 200 kHz, whether the PZT sensor is installed in the oil or on the tank, the average response sensitivity of the proposed sensing system is higher than that of the conventional PZT system. When the distance between the sensor head and ultrasonic source is 300 mm in oil, the average detection limit of the Michelson ultrasonic sensing system is about 0.26 Pa, which is about 18.6% of that of the PZT system. Moreover, experiment results show that the detectable partial discharge initial voltage for the proposed optical system is 21.5% lower than that for the PZT system. The enhanced sensitivity makes the Michelson ultrasonic sensing system a potential method to detect the small defects in power transformer.
关键词： Michelson interferometer,fiber coil effects,partial discharge,power transformer,optical fiber sensor
更新于2025-09-12 10:27:22
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Efficiency Improvement of Multi-Channel LED Driver with Selective Dimming
摘要： There is a widespread application of selective dimming of multi-channel LED drivers. In this paper, two new selective dimming methods to improve efficiency of multi-channel LED drivers are proposed. The proposed methods are based on a two-stage multi-channel LED driver that consists of an ac-dc boost power factor correction converter at its front-end and a dc-dc non- resonant converter at its second stage. Primary side digital peak current control method is applied to the dc-dc converter to control the LED peak currents during selective dimming operation. The auxiliary back-to-back switches are connected across each transformer winding either at the primary side or secondary side to perform selective dimming. The duty ratios of these auxiliary back-to-back switches are varied at lower than switching frequency of dc-dc converter to control the brightness of LED loads. The proposed topologies offer high efficiencies in both full load and during selective dimming operations, and meet the IEEE 1789 recommendation with 3 kHz dimming frequency. The design of proposed dc-dc converters, modes of operation as well as detailed theoretical analysis are presented in this paper. A 150W prototype of the proposed LED driver with a non-DSP micro- controller, is implemented to verify the feasibility of such LED drivers. Comparisons between the proposed methods and the converters reported previously are presented in the paper.
关键词： selective dimming,Multi-channel LED driver,shorting transformer windings,primary side peak current control
更新于2025-09-12 10:27:22
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Room‐Temperature Self‐Assembled Preparation of Porous ZnFe <sub/>2</sub> O <sub/>4</sub> /MIL‐100(Fe) Nanocomposites and Their Visible‐Light Derived Photocatalytic Properties
摘要： The long-term temperature induced errors caused by fiber λ/4 wave plate and the Verdet constant of sensing fiber in the all fiber current transformer (FOCT) are theoretically analyzed. A temperature related response of fiber λ/4 wave plate is adopted to compensate for the change caused by temperature related Verdet constant through choosing appropriate initial phase retardation of the λ/4 wave plate. The experimental results show high temperature-cycle accuracy in this kind of FOCT with relative error within 0.6%.
关键词： temperature induced error,λ/4 wave plate,phase delay,Verdet constant,all fiber current transformer
更新于2025-09-11 14:15:04
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A New Transformer-less Five-level Grid-Tied Inverter for Photovoltaic Applications
摘要： A new fundamental structure of a single-phase transformer-less grid connected multilevel inverter based on a switched-capacitor structure is presented in this study. By employing the series-parallel switching conversion of the integrated switched-capacitor module in a packed unit, attractive features for the proposed inverter can be obtained such as high efficiency and boosting ability within a single stage operation. Also, using a common grounding technique provides an additional advantage of reducing the leakage current. Moreover, the presented structure generates a multilevel waveform at the output voltage terminals which reduces the harmonics in the system. A peak current controller is utilized for triggering the gate of the power switches and controlling both the active and reactive powers. This results in a tightly controlled current with an appropriate quality that can be injected to the grid using a single source resource. Operating procedures, design considerations, comparison studies and test results of a 620 W prototype are also presented to validate the accuracy and feasibility of the proposed multilevel inverter.
关键词： Grid connected multilevel inverter,transformer-less inverter,switched-capacitor based structure,leakage current elimination
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Lviv, Ukraine (2019.7.2-2019.7.6)] 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - The System of Transformer Oils Laser Control by the Method of Sensing Through a Cuvette
摘要： The paper represents system of transformer oils control by the method of environment laser sensing through a cuvette. Transformer oil acts as a dielectric active medium. Measurement of the indicators is based on the resonance examination of the laser beam. The method of constructing laser photometers for evaluation of transformer oils quality is considered. The use of photometers is tested on experimental stands in the production conditions of power plants (where the oils are used for heat transfer during cooling of transformers).
关键词： laser photometry,expansion of a resonance laser beam,measurement,transformer pedals
更新于2025-09-11 14:15:04
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[IEEE 2018 2nd IEEE Advanced Information Management, Communicates, Electronic and Automation Control Conference (IMCEC) - Xi'an (2018.5.25-2018.5.27)] 2018 2nd IEEE Advanced Information Management,Communicates,Electronic and Automation Control Conference (IMCEC) - A New Electronic Current Transformer Based on Light Intensity Detection of Light Emitting Diode
摘要： A new electronic current transformer (ECT) based on light intensity detection of light emitting diode (LED) was presented. Two light emitting diodes were connected to the secondary winding. LEDs emitted infrared alternately and the radiant intensity was proportional to the primary current. Radiant intensity converted into voltage signal by two light-to- voltage optical sensors. Digital signal processor (DSP) captured the two signals and then calculated the primary current. Since secondary winding was floating potential and connected to the ground through optical fiber, the proposed electronic current transformer has the advantages of small size, low cost and strong insulation capability. The new method can be used to design protective current transformers. A 110kV/3000A prototype was designed and the experiments are conducted. The ratio error of designed prototype is 1% and phase displacement is 60’.
关键词： secondary winding,digital signal processor,light emitting diode,light intensity detection,electronic current transformer
更新于2025-09-11 14:15:04