Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
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Line Impedance Estimation Based Adaptive Droop Control Method for Parallel Inverters

  • Le, Phuong Minh (Dept. of Power Delivery, Hochiminh City University of Technology, VNU-HCM) ;
  • Pham, Xuan Hoa Thi (Dept. of Electrical and Electronic Engineering, University of Food Industry) ;
  • Nguyen, Huy Minh (Dept. of Power Delivery, Hochiminh City University of Technology, VNU-HCM) ;
  • Hoang, Duc Duy Vo (Dept. of Power Delivery, Hochiminh City University of Technology, VNU-HCM) ;
  • Nguyen, Tuyen Dinh (Dept. of Power Delivery, Hochiminh City University of Technology, VNU-HCM) ;
  • Vo, Dieu Ngoc (Dept. of Power Systems, Hochiminh City University of Technology, VNU-HCM)
  • Received : 2016.10.11
  • Accepted : 2017.09.27
  • Published : 2018.01.20
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Abstract

This paper presents a new load sharing control for use between paralleled three-phase inverters in an islanded microgrid based on the online line impedance estimation by the use of a Kalman filter. In this study, the mismatch of power sharing when the line impedance changes due to temperature, frequency, significant differences in line parameters and the requirements of the Plug-and-Play mode for inverters connected to a microgrid has been solved. In addition, this paper also presents a new droop control method working with the line impedance that is different from the traditional droop algorithm when the line impedance is assumed to be pure resistance or pure inductance. In this paper, the line impedance estimation for parallel inverters uses the minimum square method combined with a Kalman filter. In addition, the secondary control loops are designed to restore the voltage amplitude and frequency of a microgrid by using a combined nominal value SOGI-PLL with a generalized integral block and phase lock loop to monitor the exact voltage magnitude and frequency phase at the PCC. A control model has been simulated in Matlab/Simulink with three voltage source inverters connected in parallel for different ratios of power sharing. The simulation results demonstrate the accuracy of the proposed control method.

Keywords

References

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