4 3 ( ) Vol.4 No.3 6 Joural of Cetral South Uiversity (Sciece ad Techology) Ju. pq i p i q (. 483. 483) pq i p i q pq TM74 A 6777()357 A improved i p i q detectio approach of positive fudametal active ad reactive curret based o pq trasformatio HU Zhi-ku, HU Meg-yag, GUI Wei-hua, YANG Chu-hua, HE Zhi-mi (. School of Physics Sciece ad Techology, Cetral South Uiversity, Chagsha 483, Chia;. School of Iformatio Sciece ad Egieerig, Cetral South Uiversity, Chagsha 483, Chia) Abstract: To solve the problem that positive fudametal active ad reactive currets ca ot be derived from the load currets accurately i the case of oideal source voltage, a improved i p i q method was preseted accordig to sychroously pq coordiate trasformatio of both source voltage ad load curret. Sythetic phase iformatio of positive fudametal voltage ad curret was acquired ad system delay was also lowered due to collateral lowpass filterig process. Three-phase positive fudametal active ad reactive currets were obtaied by iverse pq coordiate trasformatio. The results show that the ew approach ca work out the positive sequece active ad reactive currets effectively uder ideal, usymmetrical ad distorted voltage supply coditios, thereby it ca be used to compesate for harmoic, reactive ad ubalaced currets sythetically. Key words: pq trasformatio; positive fudametal active curret; sythetic compesatio STACOM [5] 955 98 (6634) (64885) (979) 73-888364 E-mail: huzk@mail.csu.edu.c
6 ( ) 4 [67] pq [8] i p i q [9] [] [34] pq pq i p i q [5] i i i la lb lc I I I θ )] θ [ I [ I [ I θ θ ) i θ i π / 3)] θ i i i i π / 3)] π / 3) π / 3) () u u u sa sb sc U U U θ θ [ U [ U [ U θ θ u ) U θ u ) U θ u ) U u u ) π / 3) θ u π / 3) θ u θ )] u u π / 3)] π / 3)] () i la i lb i lc u sa u sb u sc I U ω θ u i θi i p i q i af i bf i cf ica icb icc PLL(Phase lock-loop) A C /3 ( ) α β C 3/ α β / / C / 3 / 3 (3) 3 / 3 / T 3/ C / 3 C (4) PLL A ω t γ ( γ [, π] ) γ () A i p i q Fig. Priciple diagram of i p i q detectig method
3 pq i p i q 7 A si ( ωt γ ) cos ( ωt γ ) C C (5) cos ( ωt γ ) si ( ωt γ ) i p i [3] q (LPF) i p i q i p q 3I cos ( θi γ ) 3I si ( θi γ ) I (6) i af i bf i cf i i af bf cf (6) si ( ωt θi ) p C 3/ C si ( ωt θi π 3) (7) iq si ( π 3) ωt θi i p i q i q i af i bf i cf (7) af ibf C icf 3/ C p si ( ωt γ ) cos ( θi γ ) si ( ωt γ π 3) cos ( θi γ ) si ( ωt γ π 3) cos ( θ ) i γ (8) () (8) i af i bf i cf γ A θ u (PLL) A ω t γ A (8) i af i bf i cf i p pq i p i q pq () () PLL A ω t γ i p i q i p i q (6) u p u q u u p q 3U cos ( θu γ ) 3U si ( θu γ ) (9) u p u q u u u af bf cf C 3/ C u u p q (9) U si ( ωt θu) U si ( ωt θu π / 3) U si ( π / 3) ωt θu () pq 3 3 (6) i p i q pq i p q (9) u p u q pq u p q pq i u i u i p i q Fig. Priciple diagram of improved i p i q detectig method
8 ( ) 4 PLL k 3 3 pq Fig.3 Vector diagram of voltage ad curret i pq coordiate system i u iu ( ) pq a ( ea ) p ( u p ) CC / 3 ib ( eb ) () iq ( uq ) ic ( ec ) i p i q u p u q i u pq i p i q 3 Matlab i p i q L t mh R t.5 Ω V A 3. 4 A A 5 p iq 3I cos ( θu θi ) cos ( θu γ ) 3I cos ( θu θi )si ( θu γ ) () i p i q i af i bf i cf i i af bf cf C 3 C p iq 4 Fig.4 Three-phase load curret waves uder ideal voltage supply coditios cos ( θ cos ( θ cos ( θ u u u θ i )si ( ωt θu) θi )si ( ωt π/3 θu) θ )si ( π/3 ) i ωt θu (3) ica icb icc STACOM i u i u pq (3) C /3 3 C 3/ 3 A A 5 A A Fig.5 Positive fudametal voltage ad active curret of phase A
3 pq i p i q 9 5 A A 5 A 6 i p i q i q 6(a) i q A A 6(b) i q 6 A A i q i p i q i p i q 8 8 3.3 GB/T 4549 993 A B C 5 5 % 5 5% 7 i p i q i q 7 i p i q (a) A i q A (b) A i q A i q 3 i q 6 A i p i q i q A Fig.6 Phase A positive fudametal voltage ad positive fudametal curret obtaied by i p i q method before ad after i q brach is broke 3. 7 A B C 5 5 i p i q i q 7 (a) A (b) B (c) C i q 7 i p i q i q Fig.7 Positive fudametal voltages ad currets obtaied by i p i q method after i q brach broke
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