Dissertation > Excellent graduate degree dissertation topics show

Study on Harmonic Currents Detecting Methods in Active Power Filters

Author: ZhangJunMin
Tutor: LiuKaiPei
School: Wuhan University
Course: Power Electronics and Power Drives
Keywords: Active filter Instantaneous reactive power theory Harmonic Detection Mean Filtering Resampling Index Impulse response Virtual instrument
CLC: TM935
Type: Master's thesis
Year: 2003
Downloads: 762
Quote: 7
Read: Download Dissertation

Abstract

Active Power Filter is a new type of power electronic devices, power system harmonic compensation. And than traditional harmonic compensation method, the active filter has great technical advantages and good prospects for development. Active filter real-time and accuracy characteristics combined with the advantages of signal processing and control technology disciplines can be optimized active power filter function, improve active power filter properties. Instantaneous reactive power theory of successful applications in the Active Power. However, due to the instantaneous reactive power theory requires two coordinate transformation, the control system will calculate the amount is very large, there will be a calculated delay, and can not achieve the true sense of the instantaneous control. This paper studies a the harmonic real time detect problems quickly. 1. Harmonic detection method based resampling and mean filtering. Firstly, starting from the instantaneous reactive power theory, applied to three-phase and single-phase circuit instantaneous reactive power theory, analysis of the instantaneous reactive power theory essentially harmonic detection based resampling and mean filtering method. The filter is a finite impulse response (FIR) digital filter having a linear phase can be applied to the three-phase circuit of the control system to follow the change of the grid at the third cycle, the control of a single phase circuit system to follow the change of the grid at a cycle; resampling theory will be measuring the signal spectrum is divided into a valid signal spectrum and invalid signal spectrum of effective signal spectrum does not allow aliasing invalid sampling frequency of the signal spectrum allows aliasing new method to determine . On the basis of theoretical analysis, this paper the method of simulation, the simulation results show that the control system not only retains the accuracy of the digital filter to overcome the long-standing digital filter follower and real-time problem of poor with higher practical value. In this section, the paper mainly in the following aspects have done a lot of work: (1) by the instantaneous reactive power theory shows that the three-phase symmetrical current three-phase three-wire grid transform to the α-β coordinates active current i_p of (reactive current I_Q) containing only 3n harmonics (n is an integer), whereby the design of a mean of a low-pass digital filter, the filter having a linear phase finite impulse response (FIR) digital The DC component filter, order as N / 3 (N sampling points of a cycle) enables i_p (i_q) no attenuation through, while the 3n-order harmonic at the amplitude attenuation of 0. The filter at one third of the cycle can accurately follow the system. In the single-phase circuit, is converted to the active current i_p α-β coordinate (reactive current I_Q) does not have such properties, design having

Related Dissertations

CLC: > Industrial Technology > Electrotechnical > Electrical measurement techniques and instruments > Frequency, waveform parameter measurement and instrumentation
© 2012 www.DissertationTopic.Net Mobile