Adaptive controller based on grid impedance estimation for stable operation of grid-connected inverters under weak grid conditions


Temiz H., KEYSAN O. , Demirok E.

IET POWER ELECTRONICS, cilt.13, ss.2692-2705, 2020 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 13 Konu: 13
  • Basım Tarihi: 2020
  • Doi Numarası: 10.1049/iet-pel.2019.1411
  • Dergi Adı: IET POWER ELECTRONICS
  • Sayfa Sayıları: ss.2692-2705

Özet

An electric grid having high impedance seen from the connection point is considered as a weak grid and it adversely affects the system stability of grid-tied voltage source inverters in renewable power devices. In this study, an adaptive controller is proposed by configuring the settling time of the phase-locked loop based on the estimated grid impedance. Pseudorandom binary sequence injection and Fourier techniques are carried out for grid impedance estimation. Impedance-based stability analysis is performed for a predetermined steady-state operation point. The proposed method is verified by a 300-kVA inverter prototype for wide-range grid impedance varying from 0.3 to 3 mH.