- 标题
- 摘要
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- 实验方案
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Effects of waveform parameters on the breakdown characteristics of OIP subjected to impulse voltages and evaluation method for waveform equivalence
摘要： The impulse voltage wave invading a transformer is not the double exponential impulse wave (DEIW) specified by the IEC but a non-standard waveform with oscillation attenuation characteristics, and this fact leads to doubts about the scientificity and optimality of insulation coordination. A key solution for this issue is the establishment of an equivalent relationship between the measured non-standard impulse voltage wave and the DEIW. In this study, a test platform of multiparameter impulse voltage was set up. Then, the authors obtained the 50% breakdown voltage (U50%) of the oil-impregnated paper (OIP) for transformer under the bipolar oscillatory attenuated impulse wave (BOAIW) and the DEIW with different waveform parameters. The effects of waveform parameters on the breakdown characteristics of the OIP were finally revealed. On the basis of experimental data and several mathematical methods, the authors established the U50% prediction mathematical models for the OIP under the BOAIW and DEIW. Based on the prediction models and the microfluctuation characteristics of measured overvoltage's waveform parameters, the authors proposed a method for evaluating the waveform equivalence. The characteristics of voltage amplitude and change rate were regarded as the two key factors for the waveform equivalence of this method.
关键词： evaluation method,breakdown characteristics,waveform equivalence,impulse voltage,oil-impregnated paper
更新于2025-09-23 15:21:21
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Body diagonal error measurement and evaluation of a multiaxis machine tool using a multibeam laser interferometer
摘要： To comprehensively evaluate the accuracy and performance of machine tools, in this paper, a novel measuring method for the body diagonal error of a machine tool using a multibeam laser interferometer as the measuring instrument is proposed. On this basis, a three-dimensional evaluation method for the body diagonal error of a machine tool is proposed. First, a method of measuring the body diagonal error of a machine tool by using a multibeam laser interferometer is proposed. Six errors for the body diagonal of a machine tool can be measured simultaneously, including three position deviations and three angle errors. The mathematical model of the relationship between the measured data and the volumetric error is established. Second, a new evaluation method for the body diagonal error is presented that takes the position deviation and attitude error into consideration. The advantage of this evaluation method is that it fills in the blanks in the evaluation method for the body diagonal error. The method can also be applied to the evaluation of linear axis error. Finally, the proposed measurement method is applied to a vertical three-axis machining centre, and the experimental results show that this measuring method is quite convenient and effective for measuring the body diagonal error of a machine tool. The proposed method is used to evaluate the body diagonal error from measurement data. The results show that the positioning error of the machine tool is 49.37 μm; the repeatability of the positioning error is 36.85 μm; and the angle errors are ? 22.47 μm/m, ? 70.9 μm/m and 29.7 μm/m. The traditional method (ISO230-6) is used to evaluate the body diagonal error from measurement data. The results show that the positioning error of the machine tool is 49.4 μm. Compared with the traditional method, the information from the proposed evaluation method is more abundant, and the evaluation method is systematic and universal.
关键词： Evaluation method,Machine tool,Measurement method,Body diagonal error,Multibeam laser interferometer
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Xi'an, China (2019.6.3-2019.6.6)] 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Reliability Evaluation of Photovoltaic Power Generation System Based on Fuzzy Layering Method
摘要： The analysis process of the overall reliability evaluation model of the traditional photovoltaic power generation system is complicated, and the shortcomings of the system weak link cannot be analyzed. This paper proposes a fuzzy hierarchical evaluation method based on sensitivity analysis to evaluate the reliability of photovoltaic power generation systems. The method judges the whole system failure factor by introducing the fault frequency, the degree of fault impact, and the second evaluation criterion of the fault detection difficulty. In particular, the Monte Carlo-based component sensitivity analysis method is used to calculate the degree of fault impact. Finally, the method of this paper is used to analyze a photovoltaic power generation system. The effectiveness of the proposed method is verified by the overall reliability analysis and the evaluation of fault factors. It is proved that the method is of great significance for analyzing the reliability of the photovoltaic system and the weak link of the system.
关键词： photovoltaic power generation system,sensitivity analysis,Monte Carlo,fuzzy layering evaluation method
更新于2025-09-16 10:30:52
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Performance and Empirical Analysis of Photovoltaic Modules Made of Different Technologies Using Capacity Evaluation Method
摘要： Performance of 5 photovoltaic (PV) modules made of different technologies (monocrystalline silicon, polycrystalline silicon, amorphous silicon, copper indium selenide and heterojunction with intrinsic layer) is evaluated according to the short-term capacity evaluation method described in IEC TS 61724-2 standard. Measurements for the analysis are obtained from the data acquisition system developed by the Laboratory for Renewable Energy Sources at the Faculty of Electrical Engineering, Computer Science and Information Technology (FERIT) Osijek which is described in the paper. Results of the performance analysis according to the IEC TS 61724-2 standard indicate that the copper indium selenide PV module Solar Frontier SF150-S has the greatest performance, therefore it is the most suitable PV module for the micro-location of Osijek, Croatia with European humid continental climate. The lowest performance of all studied PV modules is achieved by polycrystalline silicon PV module Bisol BMU 250. Empirical analysis of the relations of various electrical and meteorological parameters is performed and dependencies are evaluated. In the last section, mathematical models of PV module efficiency in relation to the module temperature are derived based on empirical analysis of measurements.
关键词： photovoltaic module,capacity evaluation method,performance analysis,empirical analysis
更新于2025-09-16 10:30:52
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[IEEE 2018 International Symposium ELMAR - Zadar, Croatia (2018.9.16-2018.9.19)] 2018 International Symposium ELMAR - Bright Lesions Detection on Retinal Images by Convolutional Neural Network
摘要： This paper is focused on automatic detection and classification of diabetic retinopathy symptoms, more specifically on the bright lesions (soft and hard exudates) as one of the primary signs suitable for diabetic retinopathy screening. We use a convolutional neural network (CNN) for bright lesions detection and evaluate achieved results using criterion based on proper comparison of each lesion with ground truth images scored by the ophthalmologist. As input data we use original and geometrically transformed retinal images from Messidor database divided into smaller blocks. In that way we enlarge the training dataset and increase classification accuracy.
关键词： Soft and hard exudates classification,Evaluation method,Retinal image,CNN,Messidor database
更新于2025-09-09 09:28:46