電力系統(tǒng)及其自動(dòng)化外文翻譯--實(shí)時(shí)檢測(cè)諧波和單相電路無功功率的方法-文庫吧資料
2025-01-14 10:06本頁面
【正文】 . [2 ] Lin B R ,Yang B R .Current harmonics elimination with a series hybrid active 外文原文 11 filter[ A ] .In。 that is， the distribution and magnitude of the detected harmonic is the same as that of the harmonic in the detected current. Fig .7 shows the simulated performance of the dynamic response of the proposed method. Assume that the electricwork current is 1800 square wave， which lags voltage by 360 . For ease of observation， suppose the amplitude of the current increases from 100 A to 200 A between 2030 ms， and the waveform of current is shown in (a). (b)(d) are respectively the outputs of the lowpass filter, the detected results of the fundamental current and the harmonic current. It is found that both the outputs of the lowpass filter and the detected results of the fundamental and harmonic currents begin to change at about 30 ms, and then stabilize at 40 ms. Therefore， the time lag is 10 ms. The time lag is caused by the filter. In fact, the lowest order of harmonics to be filtered is 2. Using the digital filtering method to get the average value in one cycle of the lowest harmonic， the steady and accurate result can be obtained after a half power cycle， . ， 10m is obvious that the performance of the dynamic response of this method is good. (a) The voltage of electric work (b) The spectrum of voltage (c) The current of electric work (d) The spectrum of current 外文原文 9 (e) The total reactive current (f) The total active current The detected total active and reactive current (a) The active current ponent (b) Harmonic and fundamental reactive current The detected active current and harmonic and fundamental reactive current (a) The current of electric work (b) The spectrum of current 外文原文 10 (c) The detected harmonic current (d) The spectrum of harmonic current Dynamically detected harmonic current (a) The current of electric work (b) The output current of LPF (c)The fundamental current (d)The harmonic current The simulation of performance of dynamic response 4 、 Conclusion In this paper, a realtime detecting method for harmonics and reactive currents on the basis of the Fryze39。s power definition in singlephase circuit. Although there is a division unit, it is not difficult to realize. Realtime detection of harmonic and reactive current Some Special Applications of the Detecting Method In Fig .l， the outputs ??tip and ??tiq vary with the input ??tus ， so this circuit can provide different reference pensations on the ground of different requirements of electric work. Three cases of application are analyzed as follows. Realtime detection of total reactive currents If the pensation is only for the reactive power, then the reactive currents need 外文原文 5 to be detected. Assume ??tis and ??tus are the current and voltage of the detected objects；then from Eqs. (1)， (2)， (4) and(9)， the outputs ??tip and ??tiq in are obtained (the derivation process is omitted here): ??tip = ? ?nnnn n w tI ?? ?? c osc os2 (10) ??tiq = ? ?nnnn nw tI ?? ?? c oss in2 (11) Obviously， ??tip is the sum of the harmonic active currents, called the total active currents. ??tiq is the sum of the harmonic reactive currents and the fundamental active currents, called the total reactive , ??tiq ,the output in Fig. 1，is used as a reference to pensate the reactive power. When only detecting the total reactive currents， there is no need to detect the unit sinusoidal signal with the same phase as the detected voltage， and hence no need to use the phaselocked loop circuit too. This is one of the merits of this method. Realtime detection of harmonic and fundamental reactive currents If ??tus = ? ?1cos2 ??wt , then, nU = ?????? ??,1,1 ,1,nno (12) Substituting Eq. (12) into Eq.(9)， we obtain P= 11cos?I (13) Then by Eq. (1) ， ??tip is expressed as ??tip = ? ?111 c o sc o s2 ?? ?wtI (14) Obviously, ??tip is the fundamental active part of the detected current, and then??tiq is the sum of harmonic and fundamental reactive currents. Therefore， the output ??tiq is used as a reference value to limit harmonics and pensate r
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