Open AccessImproving synchronization stability of grid connected converters by virtual impedance
Author(s) -
Abdoli Omid,
Gholipour Mehdi,
Hooshmand Rahmatallah
Publication year - 2021
Publication title -
iet generation, transmission and distribution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 110
eISSN - 1751-8695
pISSN - 1751-8687
DOI - 10.1049/gtd2.12091
Subject(s) - converters , electrical impedance , computer science , grid , inverter , control theory (sociology) , phase locked loop , electronic engineering , synchronization (alternating current) , output impedance , fault (geology) , engineering , topology (electrical circuits) , voltage , electrical engineering , seismology , geology , jitter , geometry , mathematics , control (management) , artificial intelligence
With the increasing penetration of inverter based distributed generation, recent grid codes do not permit the disconnection of converters as soon as fault happens. Considering the fact that electrical grids are not purely inductive, the grid connected converters face instability issues by fault occurrence. Converters applying Phase Lock Loop (PLL) are not able to synchronize with the weak grid during deep low voltage faults. This paper proposes a novel control strategy based on virtual impedance to maintain the synchronization of grid connected converters during heavy decrease of the grid voltage. Utilizing a virtual impedance and the measured current at the point of common coupling, the inverter can be virtually synchronized to a point which has a stronger connection. The virtual impedance can be a rough estimation of the line impedance or resistance from point of common coupling to the fault point. Furthermore, to avoid the need for impedance estimation, a simple technique is also proposed. Simulation results with MATLAB confirms the competence of the proposed method in improving the synchronization stability of the grid connected converters.