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Sensorless Active Damping Method for an LCL Filter in Grid-Connected Parallel Inverters for Battery Energy Storage Systems

  • Sung, Won-Yong (Department of Electrical and Computer Engineering, Sungkyunkwan University) ;
  • Ahn, Hyo Min (Department of Electrical and Computer Engineering, Sungkyunkwan University) ;
  • Ahn, Jung-Hoon (Department of Electrical and Computer Engineering, Sungkyunkwan University) ;
  • Lee, Byoung Kuk (Department of Electrical and Computer Engineering, Sungkyunkwan University)
  • 투고 : 2017.09.18
  • 심사 : 2017.10.20
  • 발행 : 2018.01.01

초록

A sensorless active damping scheme for LCL filters in grid-connected parallel inverters for battery energy storage systems is proposed. This damping method is superior to the conventional notch filter and virtual damping methods with respect to robustness against the variation of the resonance of the filter and unnecessary additional current sensors. The theoretical analysis of the proposed damping method is explained in detail, along with the characteristic comparison to the conventional active damping methods. The performance verification of the proposed sensorless active damping method shows that its performance is comparable to that of the conventional virtual damping method, even without additional current sensors. Finally, simulation and experimental results are provided to examine the overall characteristics of the proposed method.

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Fig. 1. Configuration of parallel connected inverters withLCL-filters

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Fig. 2. Circuit diagram of a single grid-connected inverter

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Fig. 3. Thevenin equivalent model of a single grid-connected inverter

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Fig. 4. Thevenin equivalent model of parallel-connectedinverters with LCL-filters

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Fig. 5. Variation of admittance of conventional parallel connected inverters

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Fig. 6. Block diagram of the conventional notch filter active damping method

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Fig. 7. Block diagram of conventional virtual resistor active damping

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Fig. 8. Block diagram of proposed sensorless damping method

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Fig. 9. Admittance of parallel connected inverters withnotch filter method

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Fig. 10. Admittance of parallel connected inverters withproposed sensorless active damping method

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Fig. 11. Estimated capacitor current and actual capacitor current

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Fig. 12. Simulation waveforms of 8-parallel-connectedinverter with conventional notch filter method

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Fig. 13. Simulation waveforms of 8-parallel-connectedinverter with conventional virtual resistor method

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Fig. 14. Simulation waveforms of 8-parallel-connectedinverter with proposed active damping method

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Fig. 15. Experimental results of the 3-parallel connectedinverter with proposed active damping method

Table 1. System parameters of inverter system

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과제정보

연구 과제 주관 기관 : Korea Institute of Energy Technology Evaluation and Planning (KETEP)

참고문헌

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