The Transactions of the Korean Institute of Power Electronics (전력전자학회논문지)

The Korean Institute of Power Electronics (전력전자학회)
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Novel Control and Design Method for Wide Stability Range of Grid Connected Inverter with LCL Filter

LCL 필터를 사용하는 계통 연계형 인버터의 넓은 안정 영역을 갖는 새로운 제어 및 설계 기법

  • Park, Kwon-Sik (Dept. of Electrical Eng., Pukyong National University) ;
  • Seo, Byung-Jun (Dept. of Electrical Eng., Pukyong National University) ;
  • Kim, Hak-Soo (Dept. of Electrical Eng., Pukyong National University) ;
  • Nho, Eui-Cheol (Dept. of Electrical Eng., Pukyong National University)
  • Received : 2018.10.23
  • Accepted : 2018.11.13
  • Published : 2018.12.20
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Abstract

This study proposes a novel control and design method for a grid-connected inverter with an LCL filter without damping. The current resonance phenomenon must be considered when designing the grid-connected inverter system with an LCL filter. Passive or active damping is used in the inverter system to reduce the resonant current. However, passive damping reduces the efficiency of the system, and active damping methods are complex. If the resonant frequency is in a specific region, then the system will be unstable. This study examines the process of stabilizing the entire region without resonant damping. The validity of the proposed method is verified through simulation and experimentation.

Keywords

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Fig. 1. Grid connected inverter system with LCL filter.

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Fig. 2. Block Diagrams of each Active Damping Method.

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Fig. 4. Block diagram of the grid connected inverter system.

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Fig. 5. Comparison of frequency response characteristics in S-domain and Z-domain.

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Fig. 6. Changing the resonant frequency with the variation of capacitor value.

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Fig. 7. Block diagram of a proposed method.

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Fig. 8. Comparison of frequency response characteristics with and without LPF(fL=3000[Hz], ζ=1).

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Fig. 9. Changing the resonant frequency with the variationof capacitor value with LPF(fL=3000[Hz], ζ=1).

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Fig. 10. Pole-zero map of feedback system according to the cut off frequency of LPF.

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Fig. 11. Grid voltage and current waveforms in simulation results.

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Fig. 12. Experimental waveforms of vg, i2(vg : 100 [V/div], i2: 10 [A/div], 5[ms/div]).

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Fig. 3. Stability Region of the GCF(Grid Current Feedback) method.

TABLE I INVERTER SYSTEM PARAMETERS

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References

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