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New spectral decomposition based approach for flicker evaluation of electric arc furnaces

IET GENERATION TRANSMISSION & DISTRIBUTION 2009年第4期3卷 393-411页

作者： Koese, N. Salor, Oe. TUBITAK Uzay Power Elect Grp TR-06531 Ankara Turkey METU Dept Elect & Elect Engn TR-06531 Ankara Turkey

A spectral decomposition-based approach is proposed to estimate the light flicker caused by electrical arc furnaces (EAFs) where the system frequency deviates significantly due to the EAF operation. Analytical expressions of the instantaneous light flicker sensation are obtained beginning from a voltage waveform and these expressions are used to obtain a flicker estimation method based on the IEC flickermeter. In the proposed method, the leakage effect of the fft algorithm due to fundamental frequency variation is reduced by employing a spectral amplitude correction around the fundamental frequency. The eye-brain weighting curve is realised comparing the voltage spectrum with the tabulated normalised IEC flickermeter responses for sinusoidal voltage fluctuations of the IEC standard. The proposed method is tested on both simulated data and field data obtained from three different EAF plants. The comparison with the digital realisation of the IEC flickermeter shows that the method gives satisfactory estimations of both the instantaneous flicker sensation and the short term flicker severity with low computational complexity. The method is especially useful for all other conditions such as disturbances and subsequent system transients where the system frequency deviates without the need for online sampling rate adjustment.

关键词： amplitude calibration Frequency variation Arc furnaces International Electrotechnical Commission voltage waveform Flicker spectral representation fft algorithm system frequency

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Factorised polar-format back-projection algorithm

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IET RADAR SONAR AND NAVIGATION 2015年第7期9卷 875-880页

作者： Yang, Zemin Xing, Mengdao Zhang, Yimin D. Sun, Guangcai Bao, Zheng Xidian Univ Natl Lab Radar Signal Proc Xian 710071 Peoples R China Villanova Univ Ctr Adv Commun Villanova PA 19085 USA

The back-projection algorithm (BPA) is a useful technique for synthetic aperture radar (SAR) imaging. The fast factorised BPA (FFBPA) recursively partitions the back-projection integral, thus significantly reducing the overall computation complexity corresponding to the improvement obtained by the fft algorithm compared with the direct implementation of the discrete Fourier transform. In this study, the authors propose a new fast method, termed as the factorised polar-format BPA (FPFBPA), which combines the polar format algorithm and the factorised back-projection concept. It is demonstrated that, when the first-stage subaperture in the FPFBPA contains more than 3 pulses, the proposed method further reduces the computation complexity comparing with FFBPA, provided that the same interpolation method is used. The proposed algorithm is also capable of processing curved orbit and multi-mode SAR data. The effectiveness of the proposed algorithm is verified by the processed results using measured airborne data.

关键词： synthetic aperture radar radar imaging computational complexity discrete Fourier transforms interpolation airborne radar factorised polar format back-projection algorithm synthetic aperture radar imaging multimode SAR imaging fast factorised BPA FFBPA back-projection integral computation complexity reduction fft algorithm discrete Fourier transform factorised polar format BPA FPFBPA interpolation method airborne data measurement fast Fourier transform

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Measurement of power system harmonic based on adaptive Kaiser self-convolution window

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IET GENERATION TRANSMISSION & DISTRIBUTION 2016年第2期10卷 390-398页

作者： Yao, Wenxuan Teng, Zhaosheng Tang, Qiu Gao, Yunpeng Hunan Univ Dept Elect & Informat Engn Changsha 410082 Hunan Peoples R China

As the rapid development in power electronic devices, the harmonic pollution becomes one of principle power quality problems in power system. The fast Fourier transform (fft) is widely used for analysing and measuring power system harmonics. However, the limitation of the fft such as an aliasing effect, spectrum leakage picket-fence effect, would contribute to inaccuracy results. Furthermore, the real power system harmonic is actually a non-stationary signal while fft is a tool for stable signal. This study focuses on a novel fft based method for time-varying power system harmonic measurement. The harmonic signal is preprocessed by infinite impulse response filter bank and Teager-Kaiser energy operator for fast detection of instability onset time. Then an adaptive Kaiser self-convolution window-based interpolated fft algorithm is used to estimate each harmonic component. The results of both simulation and practical implementation show that the proposed method is suitable to deal with time-varying harmonic and achieves a higher accuracy compared with the traditional fft-based techniques.

关键词： Power system harmonics power systems Infinite impulse response filters fft algorithm Power measurement Fast Fourier transform

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Measuring power system harmonics and interharmonics by an improved fast Fourier transform-based algorithm

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IET GENERATION TRANSMISSION & DISTRIBUTION 2008年第2期2卷 192-201页

作者： Chang, G. W. Chen, C. I. Liu, Y. J. Wu, M. C. Natl Chung Cheng Univ Dept Elect Engn Chiayi 621 Taiwan

The fast Fourier transform (fft) has been widely used for the signal processing because of its computational efficiency. Because of the spectral leakage and picket-fence effects associated with the system fundamental frequency variation and improperly selected sampling time window, a direct application of the fft algorithm with a constant sampling rate may lead to inaccurate results for continuously measuring power system harmonics and interharmonics. An improved fft-based algorithm to measure harmonics and interharmonics accurately is proposed. In the proposed algorithm, a frequency-domain interpolation approach is adopted to determine the system fundamental frequency, and the interpolatory polynomial method is applied to reconstruct the sampled time-domain signal;it is followed by using the fft to calculate the actual harmonic components. Then, the frequency-domain interpolation is again applied to find the interharmonic components. The performance of the proposed algorithm is validated by testing the actual measured waveforms. Results are compared with those obtained by directly applying a typical fft algorithm and by the IEC grouping method. It shows that the solutions determined by the proposed algorithm are more accurate, and a reasonable computational efficiency is maintained.

关键词： power system measurement time-domain signal power system interharmonics interpolatory polynomial method polynomials power system harmonics fast Fourier transform-based algorithm fft algorithm picket-fence effects spectral leakage Power supply quality and harmonics frequency-domain interpolation approach Power system measurement and metering Interpolation and function approximation (numerical analysis) interpolation frequency-domain analysis Integral transforms in numerical analysis power system harmonics measurement fast Fourier transforms

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Analysis of circulant symmetric coupled strip lines

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JOURNAL OF ELECTROMAGNETIC WAVES AND APPLICATIONS 2002年第7期16卷 977-994页

作者： Cheldavi, A Amirhosseini, MK Iran Univ Sci & Technol Tehran 16844 Iran

In this paper a new kind of coupled transmission lines called circulant symmetric coupled microstrip structure and its application as an interconnect in high speed integrated circuits will be introduced. Also a simple method for frequency domain and transient analysis of this kind of coupled microstrip transmission lines is presented. First the capacitance ([C]) and inductance ([L]) matrices of the structure are derived. An special matrix is then defined to decompose the differential equations of the lines and diagonalize the [L] and [C] matrices (modal decomposition method). Finally the frequency domain solution is obtained and fft algorithm is used to find the time domain response of the line.

关键词： Multiconductor transmission-lines Time response Nonuniform Interconnections Simulation CENTROSYMMETRIC simulating TIME DOMAIN RESPONSE fft algorithm Nonuniform coupled transmission lines Frequency-domain analysis Strip Line Device Component Time response Transient analysis circulation superconducting microstrips

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Modeling and analysis of substrate coupling in integrated circuits

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IEEE JOURNAL OF SOLID-STATE CIRCUITS 1996年第3期31卷 344-353页

作者： Gharpurey, R Meyer, RG UNIV CALIF BERKELEY DEPT ELECT ENGN & COMP SCIBERKELEYCA 94720 UNIV CALIF BERKELEY ELECTR RES LABBERKELEYCA 94720

This paper describes a fast and accurate simulator for characterizing the effects of substrate coupling on integrated-circuit performance. The technique uses the electrostatic Green function of the substrate medium and the fast Fourier transform algorithm, It is demonstrated that this technique is suitable for optimization of layout for minimization of substrate coupling, Analysis of substrate coupling in different types of substrates and the utility of guard rings in different types of substrates is also discussed. Experimental verification of the models is presented.

关键词： coupling layouts Guard rings fft algorithm Substrates verification model Electronic circuits Integrated circuits Modeling

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Computer simulated holography and computer generated holograms

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AMERICAN JOURNAL OF PHYSICS 1996年第4期64卷 472-478页

作者： Trester, S LONG ISL UNIV DEPT PHYS CW POST CAMPUS BROOKVILLE NY 11548 USA

The success of calculating and displaying the Fraunhofer diffraction patterns for various apertures using the fast Fourier transform algorithm on an IBM compatible personal computer has been well documented in the recent literature. In this paper the technique is extended to the simulation of optical holography on the computer. Using this method, Fourier transform holograms are easily generated. Their. optically reconstructed images are compared to the ones reconstructed and displayed by the computer. These computer generated images allow for a quantitative verification of the holographic theory presented and can serve:as the basis of a tutorial on this subject suitable for advanced undergraduates. The calculations and graphics were accomplished using the MATHCAD(R) for WINDOWS(TM) software package. (C) 1996 American Association of Physics Teachers.

关键词： Computers Holograms Holography graphic images fft algorithm apertures

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THE STRUCTURE OF VECTOR RADIX FAST FOURIER-TRANSFORMS

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND SIGNAL PROCESSING 1989年第9期37卷 1415-1424页

作者： WU, HR PAOLONI, FJ Department of Electrical and Computer Engineering University of Wollongong Wollongong NSW Australia

A general form of the matrix representation for multidimensional, vector-radix, fast Fourier transform (fft) algorithms using decimation-in-frequency is presented. A structure theorem is devised to construct systematically various vector-radix decimation-in-frequency fft algorithms from their 1-D counterparts. Logic diagrams are provided to facilitate the software and hardware implementation of the algorithms. The computational complexity of several of the algorithms is considered.

关键词： Matrix representation fft algorithm algorithms logic diagram Fast Fourier transform Fourier Transform computer software

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Analysis of isolated self-excited induction generator feeding a rectifier load

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IEE PROCEEDINGS-GENERATION TRANSMISSION AND DISTRIBUTION 2002年第1期149卷 90-97页

作者： Kuo, SC Wang, L Natl Cheng Kung Univ Dept Elect Engn Tainan 70101 Taiwan

Both transient and steady-state performances of in isolated self-excited induction generator (SEIG) supplying a rectifier load are presented, A hybrid model based on abc and q-d induction machine models is employed to describe the dynamic equations of the studied system to improve simulation results. The stator voltage equations of the SEIG studied are described by a three-phase abc model which can be directly interfaced to the rectifier circuit. The rotor variables are properly transformed into q-d co-ordinates and the elements in the rotor inductance matrix are time-invariant. The controlled rectifiers, including both semi and full converters, are modelled by using three switching functions, which are designated to be tristate switches for each converter leg. Combining the SEIG model proposed with the rectifier model, the transient characteristics of the SEIG under various loading conditions are simulated and evaluated. The fft algorithm is used to analyse the voltage and current harmonic content Under steady-state conditions. Experimental results obtained from a laboratory 1.1 kW induction machine driven by a DC motor ire also performed to confirm the effectiveness of the proposed approach.

关键词： current harmonic content Asynchronous machines fft algorithm transient performances Power convertors and power supplies to apparatus AC-DC power convertors load (electric) machine theory voltage harmonic content loading conditions dynamic equations Linear algebra (numerical analysis) fast Fourier transforms steady-state performances stators matrix algebra asynchronous generators rotors Integral transforms in numerical analysis switching functions exciters abc induction machine models rectifier load stator voltage equations q-d induction machine models controlled rectifiers rotor inductance matrix 1.1 kW rectifying circuits isolated self-excited induction generator transient characteristics

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Low power receiver architectures for multi-carrier CDMA

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IEE PROCEEDINGS-CIRCUITS DEVICES AND SYSTEMS 2002年第4期149卷 227-233页

作者： McCormick, AC Grant, PM Thompson, JS Arslan, T Erdogan, AT Univ Edinburgh Dept Elect & Elect Engn Edinburgh EH9 3JL Midlothian Scotland

The implementation of multi-carrier code division multiple access (MC-CDMA) receivers in digital hardware is considered. A low power algorithm is proposed which treats the received signal as a block of symbols, rather than processing the symbols individually. This reduces power by holding one input to the multiplier circuits used in the multi-carrier combiner multiplication constant for a number of clock cycles. This produces a 50% reduction in power consumption for a multi-user detection combiner circuit. This algorithm is also extended to the fast Fourier transform (fft) block and allows an overall power drain reduction of 13% for the whole receiver. A software configurable version of the circuit, which allows a trade-off between power reduction and processing delay, is also described.

关键词： multi-user detection combiner circuit software reconfiguration fft algorithm multi-carrier CDMA multiplying circuits code division multiple access fast Fourier transforms digital hardware radio receivers multiplier circuit low-power electronics multiplication constant low-power receiver architecture

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