Mobile QR Code QR CODE : The Korean Institute of Power Electronics
Title An Improved Grid Impedance Estimation using PQ Variations
Authors Je-Hee Cho ; Yong-Wook Kim ; Rae-Young Kim
DOI 10.6113/TKPE/2015.20.2.152
Page pp.152-159
ISSN 1229-2214
Keywords Grid impedance estimation; Grid connected inverter; Phase looked loop (PLL); PQ variations
Abstract In a weak grid condition, the precise grid impedance estimation is essential to guaranteeing the high performance current control and power transfer for a grid-connected inverter. This study proposes a precise estimation method for grid impedance by PQ variations by employing the variation method of reference currents. The operation principle of grid impedance estimation is fully presented, and the negative impact of the phase locked loop is analyzed. Estimation error by a synchronization angle in the park’s transformation using the phase locked loop is derived. As a result, the variation method of reference currents for accurate estimation is introduced. The validation of the proposed method is verified through several simulation results and experiments based on a 2-kW voltage source inverter prototype.