Open AccessAn Improved Grid Impedance Estimation using PQ Variations
Author(s) -
Je-Hee Cho,
Yong-Wook Kim,
Rae-Young Kim
Publication year - 2015
Publication title -
jeollyeok jeonja hakoe nonmunji/jeonlyeog jeonja haghoe nonmunji
Language(s) - English
Resource type - Journals
eISSN - 2288-6281
pISSN - 1229-2214
DOI - 10.6113/tkpe.2015.20.2.152
Subject(s) - grid , electrical impedance , control theory (sociology) , computer science , synchronization (alternating current) , inverter , phase locked loop , transformation (genetics) , phase angle (astronomy) , voltage , electronic engineering , engineering , mathematics , electrical engineering , control (management) , telecommunications , physics , channel (broadcasting) , biochemistry , chemistry , geometry , artificial intelligence , astronomy , jitter , gene
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