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Definition and digital algorithms of dielectric loss factor for condition monitoring of high-voltage power equipment with harmonics emphasis

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IEE PROCEEDINGS-GENERATION TRANSMISSION AND DISTRIBUTION 2005年第3期152卷 309-312页

作者： Li, Q Zhao, T Siew, WH Shandong Univ Sch Elect Engn Jinan 250061 Shandong Prov Peoples R China Univ Strathclyde Dept Elect & Elect Engn Glasgow G1 1XW Lanark Scotland

Experience and applications of currently available methods for online monitoring and diagnostics of high-voltage power apparatus are briefly reviewed. Based on dielectric physics, a new definition of dielectric loss factor with harmonics emphasis is proposed to evaluate the operational conditions of power apparatus on a more reasonable basis, along with corresponding digitised algorithms. Two approaches, namely the decoupling algorithm and the approximating algorithm, are presented to implement the methodologies with the new definition of dielectric loss factor. The impact of background noise and power-frequency fluctuation on estimation accuracy are analysed by computer simulations, showing better application qualities of the approximating algorithm than the decoupling algorithm. A comprehensive strategy of simultaneous monitoring of sum current, dielectric loss factor, resistive current and capacitive current is recommended to give an effective assessment and diagnosis.

关键词： Simulation techniques dielectric physics resistive current harmonics emphasis Power engineering computing Dielectric materials and properties digital algorithms power engineering computing approximating algorithm computer simulations high-voltage power equipment background noise digital simulation harmonic distortion power apparatus dielectric loss factor online condition monitoring condition monitoring Dielectric variables measurement Power apparatus and electric machines dielectric loss measurement decoupling algorithm power-frequency fluctuation capacitive current

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Definition and digital algorithms of dielectric loss factor for condition monitoring of high voltage power equipment with harmonics emphasis

Definition and digital algorithms of dielectric loss factor ...

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IEEE PES Power Systems Conference and Exposition

作者： Li, QM Zhao, T Shandong Univ Sch Elect Engn Jinan 250061 Shandong Prov Peoples R China

ISBN: (纸本)078038718X

Experience and applications of the currently available methods for on-line monitoring and diagnostics of high voltage power apparatus is briefly reviewed. Based on the dielectric physics, a new definition of dielectric loss factor with harmonics emphasis is proposed to evaluate the operational conditions of power apparatus on a more reasonable basis, along with corresponding digitised algorithms. Two approaches, namely the decoupling algorithm and the approximating algorithm, are presented to implement the methodologies with the new definition of dielectric loss factor. The impacts of background noise and power frequency fluctuation on estimation accuracy are analysed by computer simulations showing better application qualities, of the approximating algorithm than the decoupling one. A comprehensive strategy of simultaneous monitoring of the sum current, dielectric loss factor, resistive current and capacitive current is recommended to give an effective assessment and diagnosis of both the insulation degradation and heat behaviours.

关键词： dielectric loss factor on-line monitoring digital algorithms harmonics

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NEW digital SIGNAL-PROCESSING algorithms FOR FREQUENCY DEVIATION MEASUREMENT

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IEEE TRANSACTIONS ON POWER DELIVERY 1992年第3期7卷 1563-1573页

作者： KEZUNOVIC, M SPASOJEVIC, P PERUNICIC, B ELEKTROTEHN FAK YU-71000 SARAJEVO YUGOSLAVIA

This paper introduces two digital signal processing algorithms for frequency deviation measurement. The algorithms are derived using a new signal processing scheme based on quadratic forms of signal samples. These algorithms provide high measurement accuracy over a wide range of frequency changes. One is designed for measurements of small deviations of the nominal frequency whereas the other one measures off-nominal frequency deviations. Performance of the algorithms is evaluated using computer simulation tests.

关键词： FREQUENCY MEASUREMENTS digital algorithms SIGNAL PROCESSING QUADRATIC FORMS

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Analysis of Time Resolution in Monolithic Crystal PET detectors using different digital Time Extraction algorithms

Analysis of Time Resolution in Monolithic Crystal PET detect...

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IEEE Nuclear Science Symposium/Medical Imaging Conference

作者： Monzo, J. M. Lerche, C. W. Martinez, J. D. Esteve, R. Toledo, J. Herrero, V. Ferrando, N. Aliaga, R. J. Colom, R. J. Gadea, R. Sanchez, F. Mora, F. J. Benlloch, J. M. Sebastia, A. Univ Politecn Valencia ITACA Inst DSD Grp Valencia 46022 Spain CSIC IFIC Nucl Med Phys Grp E-46980 Valencia Spain

ISBN: (纸本)9781424427147

New digital PET detectors are based in an early digitalization of the detector signals. In these systems, digital signal processing (with FPGAs, DSPs or both) is a lied to extract the information from the detected events. algorithms adapted to the available hardware resources should be proposed to detect gamma-ray energy, impact position and event arrival time. In this paper, eight different digital algorithms for time extraction are evaluated. Each of them is a combination of different signal processing methods, which are low pass filter interpolation, charge calculation, bipolar signal digital constant fraction algorithm and digital constant fraction algorithm. It is important to analyze how electronic noise, ambient noise, clock jitter and signal shaping affect to the time resolution obtained using the different proposed algorithms. The developed test allows us to find the best electronics and to choose the appropriated algorithm to be implemented. Results show that both the analog electronics shaping time and the noise have an important influence in timing resolution.

关键词： Positron Emission Tomography Gamma Ray Imaging Detectors Event time detection digital algorithms System simulation Time Resolution

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NEW digital SIGNAL-PROCESSING algorithms FOR FREQUENCY DEVIATION MEASUREMENT

NEW DIGITAL SIGNAL-PROCESSING ALGORITHMS FOR FREQUENCY DEVIA...

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TRANSMISSION AND DISTRIBUTION CONF OF THE IEEE POWER ENGINEERING SOC

作者： KEZUNOVIC, M SPASOJEVIC, P PERUNICIC, B

ISBN: (纸本)0780302192

Two digital signal processing algorithms for frequency deviation measurement are introduced. The algorithms are derived using a new signal processing scheme based on quadratic forms of signal samples. These algorithms provide high measurement accuracy over a wide range of frequency changes. One is designed for measurements of small deviations of the nominal frequency, whereas the other one measures off-nominal frequency deviations. The performance of the algorithms is evaluated using computer simulation tests.

关键词： FREQUENCY MEASUREMENTS digital algorithms SIGNAL PROCESSING QUADRATIC FORMS

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A Low-Cost Evaluation Tool for Synchronization Methods in Three-Phase Power Systems

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APPLIED SCIENCES-BASEL 2025年第3期15卷

作者： Reyes, Marcelo E. Melin, Pedro E. Espinosa, Eduardo Baier, Carlos R. Pesce, Cristian Cormack, Benjamin Univ Bio Bio Fac Engn Concepcion 4051381 Chile Univ Bio Bio Dept Elect & Elect Engn Concepcion 4051381 Chile Univ Catolica Santisima Concepcion Fac Engn Dept Elect Engn Concepcion 4090541 Chile Univ Talca Fac Engn Dept Elect Engn Curico 3344158 Chile Univ La Frontera Dept Elect Engn Temuco 4780000 Chile

The use of renewable energy sources (RESs) together with energy storage systems (ESSs) allows for smoothing power variations, thus improving power backup capabilities and power quality in the electric power grid. These applications require power converters to transfer energy between the renewable generator or energy storage and the power grid. In any case, the control algorithm of the power converter requires the synchronization method to provide a correct estimation of the instantaneous voltage of the power grid. This work provides engineers and researchers with an accessible platform at a low cost (less than USD 100) and a methodology for the experimental validation of digital synchronization algorithms as a step before their implementation in grid-connected equipment. The methodology evaluates the performance of the digital algorithms when there are variations in amplitude, frequency, phase, and harmonic content in the emulated three-phase power grid, as well as the execution times (tex), while a digital platform emulates the electrical signals and generates reference signals for the evaluation. To illustrate this proposal, two synchronization algorithms-SRF-PLL and DSOGI-PLL with a low-pass filter-are implemented in a digital controller and tested. The evaluation tool confirms the algorithms' performance and shows that the execution time of DSOGI-PLL is 91% longer than that of SRF-PLL, which is well known in the literature.

关键词： digital algorithms digital control evaluation tool phase-locked loop synchronism method synchronism techniques

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Definition of Instantaneous Dielectric Loss Factor and digital Algorithm for Online Monitoring

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IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT 2009年第3期58卷 666-673页

作者： Li, Qingmin Zhang, Li Zhao, Tong Shandong Univ Sch Elect Engn Jinan 250061 Peoples R China

Among the digital algorithms currently alvailable for online monitoring of the dielectric loss factor of power apparatus, there are unavoidable limitations, such as that most of them must strictly meet the synchronous sampling criterion simultaneously with a precondition that the power frequency must be invariable in the sampling periods. This paper presents a unique definition and a corresponding digital algorithm of the instantaneous dielectric loss factor. The theoretical basis of the algorithm is also deduced. In a nonstationary signal environment where power frequencies are randomly variable, the algorithm can accurately track the instantaneous frequency of power signals, recursively calculate the parameters of parallel equivalent circuit, and, finally, figure out the waveform of the instantaneous dielectric loss factor. Simulations and experimental results show that the proposed algorithm renders good application performance without being affected by the limitations incurred from synchronous sampling and harmonics.

关键词： digital algorithms frequency tracking instantaneous dielectric loss factor online monitoring recursive method

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Evaluation of digital metering methods used in protection and reactive power compensation of micro-grids

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RENEWABLE & SUSTAINABLE ENERGY REVIEWS 2016年 62卷 260-279页

作者： Samet, Haidar Shiraz Univ Sch Elect & Comp Engn Shiraz Iran

Stand-alone micro-grids (MGs) and grid-connected MGs with high penetration level of Distributed Generation (DG) are growing at a fast rate. In these grids, the power quality disturbances such as harmonics, inter-harmonics and deviation from the fundamental frequency are widespread. The influence of these disturbances on two categories of digital metering algorithms is evaluated in this paper. The first category is related to the measurement of the fundamental frequency component of current and voltage signals, which are used as inputs of the digital protection algorithms. Most of the relays only use fundamental frequency component of their input voltage and current signals to fulfill the desired protective functions. The accuracy of the protective relays highly depends on the performance of the applied algorithms for extracting the fundamental components. The second evaluated category is related to the reactive power calculation algorithms, which are used in the static VAr compensator (SVC) control system. Utilizing SVC is growing due to the DGs such as wind turbines magnify voltage fluctuations called flicker. Since the SVC compensates only the reactive power related to the fundamental frequency component, the reactive power signal should not be sensitive to the harmonics. In addition, the reactive power calculation should be fast enough that SVC can follow the abrupt changes to mitigate the flicker, efficiently. In this paper, frequency deviation, harmonic, and inter-harmonic phenomena are considered as the most causes for power quality problems. Their influence in digital metering algorithms is evaluated. It is confirmed that defining new indices is mandatory to fully reflect algorithms' accuracy and efficiency. Furthermore, the field measurements of instantaneous voltage and current of a wind farm and electric arc furnaces are used for the evaluation. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Micro grid Protection Reactive power Compensation digital algorithms Harmonics

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Analysis of time resolution in a dual head LSO plus PSPMT PET system using low pass filter interpolation and digital constant fraction discriminator techniques

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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2009年第1-2期604卷 347-350页

作者： Monzo, Jose M. Lerche, Christoph W. Martinez, Jorge D. Esteve, Raul Toledo, Jose Gadea, Rafael Colom, Ricardo J. Herrero, Vicente Ferrando, Nestor Aliaga, Ramon J. Mateo, Fernando Sanchez, Filomeno Mora, Francisco J. Benlloch, Jose M. Sebastia, Angel Univ Politecn Valencia Digital Syst Design Grp ITACA Inst Valencia 46022 Spain CSIC IFIC Inst Nucl Med Phys Grp Paterna 46980 Spain

PET systems need good time resolution to improve the true event rate, random event rejection, and pile-up rejection. In this study we propose a digital procedure for this task using a low pass filter interpolation plus a digital Constant Fraction Discriminator (DCFD). We analyzed the best way to implement this algorithm on our dual head PET system and how varying the quality of the acquired signal and electronic noise analytically affects timing resolution. Our detector uses two continuous LSO crystals with a position sensitive PMT. Six signals per detector are acquired using an analog electronics front-end and these signals are processed using an in-house digital acquisition board. The test bench developed simulates the electronics and digital algorithms using Matlab (R). Results show that electronic noise and other undesired effects have a significant effect on the timing resolution of the system. interpolated DCFD gives better results than non-interpolated DCFD. In high noise environments, differences are reduced. An optimum delay selection, based on the environment noise, improves time resolution. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Positron emission tomography Event time detection digital algorithms System simulation Position sensitive detector

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Comparison of four digital maximum frequency estimators for doppler ultrasound

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Ultrasound in Medicine and Biology 1988年第5期14卷 355-363页

作者： Y.L.Mo, Larry Yun, Louis C.M. Cobbold, R.S.C. Institute of Biomedical Engineering University of Toronto Toronto M5S 1A4 Canada

The performance of four methods for digitally estimating the maximum frequency waveform from the Doppler ultrasound spectrum, are described. The methods investigated are: a percentile method, D'Alessio's threshold crossing method [D'Alessio T. (1985) "Objective" algorithm for maximum frequency estimation in Doppler spectral analysers. Med. Biol. Engng and Comput. 23, 63-68.], a modified threshold crossing method, and a new hybrid algorithm. Evaluations of the variance and bias were performed using stationary simulated continuous wave (CW) Doppler signals of different bandwidths and signal/noise ratios (SNR) of 9 and 17 dB. Furthermore, a simulated nonstationary Doppler signal, similar to that from a normal internal carotid artery, was also used to compare the various methods. Overall, it was found that the modified threshold method and the new hybrid method have the best performance over a wide range of signal and noise conditions;however, D'Alessio's method also performs well for low SNR's. © 1988.

关键词： digital algorithms Doppler ultrasound spectrum Maximum frequency estimation

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