4 5 Vol.4 No.5 22 8 Power Sytem Protection and Control Aug., 22 A method o power ytem harmonic detection baed on wavelet tranorm ZENG Rui-jiang, YANG Zhen-bin 2, LIU Hui-chao 2 (. Electric Power Reearch Intitute, Guangdong Power Grid Corporation, Guangdong 5, China; 2. Anhui CSG Smart Grid Technology Co. Ltd, Heei 2388, China) Abtract: Baed on the wavelet multi-reolution analyi, a kind o ampling requency election method i propoed. It i eective in extracting the undamental wave ignal and the given harmonic ignal. Harmonic ignal i analyzed with wavelet tranorm, reaonable decompoition level are elected, and then the harmonic detection reult caued by ampling requency in dierent range are dicued. The correctne o the method i teted by imulation. Finally, the method i ued in F282DSP baed harmonic detection device or long time operation and tet in the ditribution network automation ytem. Reult how that the method ha a at computing peed, a quick reaction, and a real-time tracking o harmonic change. Key word: wavelet tranorm; harmonic analyi; DSPF282; ampling requency; multi-reolution analyi TM7 A 674-345(22)5-35-5 (FFT) [-2] [3] - [4-5] [6-7] Matlab F282DSP [8] L 2 ( R) () t () t (Continuou
- 36 - Wavelet Tranorm, CWT) t WT a, t, a, t t d t a, R, a a R a () WT ( a,b) () t () t a b [9] VVWV2W2 WV3W3W2W (2) x() t V W V V Mallat d j a j j d j a j A j D j V 4 V 3 V 2 W 4 Fig. Decompoition diagram o wavelet tranorm multireolution analyi o our layer pace V W 3 V W 2 W [] c 2 c [-2] 2 3 a 4 d4 d3 d2 d 32 6 8 4 Fig. 2 Frequency diviion map o wavelet tranorm our layer decompoition a5 d5 64 32 d 4 6 d 3 8 d 2 4 Fig. 3 Frequency diviion map o wavelet tranorm ive layer decompoition 3 5 Hz 5 Hz 25 Hz j j 2 2 25 Hz 35 Hz 45 Hz j j2 2 2 (3) j Hz < < 3 Hz (4) 5 Hz < < 25 Hz 25 Hz < < 75 Hz 87 Hz < <2 Hz d 2 2 (5) (6) (7) (4)~(7)
- 37 - (3) 3 5 (4) ~(6) 5 Hz < < 75 Hz (8) 4 8 Hz < < 5 6 Hz 96~2 75 Hz < < 25 Hz 5 6 Hz < < 8 Hz 25 Hz < < 3 Hz 8 Hz < < 9 6 Hz 3 Hz 96Hz 5 Hz (3) ~ Hz Hz(8) 5 Hz < < 75 Hz Matlab db4 t in2π 5t 3 5 7 3.3in2π 5t 5.2in2π 25t 7.in2π 35t ' t in2π 5 t+.3in2π 5 t +.2in 2π 25 t +.in 2π 35t (8) 4 8~5 6 Hz 5 6 Hz 2 3 A53 D55 D47 D3 4 3 5 7 A5 D 3 5 7 D5D4D3 3 2 2 2 5 5 FFT 2 3 4 5 DFFT 2 3 4 5 D2FFT 2 3 4 5 D3FFT 2 3 4 5 3 2 3 2 2 2 FFT 2 3 4 5 A5FFT 2 3 4 5 D4FFT 2 3 4 5 D5FFT 2 3 4 5 Fig. 4 Simulation diagram o ampling requency in ampling range
- 38-6 4 Hz 28 5 4 7 D3 D4 7 D4 Fig. 5 Simulation diagram o ampling requency greater than the ampling range 4 Hz 8 6 4 3 D4 5 D3 F282DSP Matlab 7 [3] Fig. 6 Simulation diagram o ampling requency le than the ampling range 2 2..5..5.2.25 2 2..5..5.2.25 Fig. 7 Application example igure Fig. 8 Structure diagram o harmonic detecting device
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