Output voltage regulation based on P plus resonant control in islanded mode of microgrids

Output Voltage Regulation for Harmonic Compensation under Islanded Mode of Microgrid

“…In this mode, the attenuation of the current harmonics is possible by installing a L or LCL filter at the inverter output. On the other hand, a grid-connected inverter with a L or LCL filter needs to operate instantly as a voltage source after being disconnected from the main grid due to grid faults or strategic islanding [8]. In islanded mode, the inverter is defined as a voltage source to supply the full local load demand in place of the main grid.…”

“…In this paper, the P+MR based multi loop control coordinated in αβ-and abc-frames is selected to compensate for the voltage harmonics with a rapid dynamic response referred in [7], [8]. The controller gains based on specific modeling are tuned using the bode plot and root locus.…”

“…The controller gains based on specific modeling are tuned using the bode plot and root locus. Unlike [7], [8], changes of each control gain are added under the root locus-based control gain selection criteria to analyze the characteristics of each gain and mutual influence. This analysis is extended to the Bode plot-based P+MR term to make gain optimizing be possible to handle the unexpected variable occurrences, such as system parameter mismatch, etc.…”

“…To solve the abovementioned problems, there have been several studies on multi-looped controllers, which can achieve the fast dynamic response or harmonics compensation possible despite the inverter output filter [7], [8], [11]- [17]. The double loop controller with an outer PI voltage loop and an inner P or PI current loop was introduced for the operation of a parallel UPS [13].…”

“…However, it is neglected how to design parameters of the PR controller and its specific control characteristics. In [7], [8], the P+MR control was selected with the specific system modeling to determine the gain parameters properly. On the other hand, its system analysis was insufficient to understand the various response tendencies according to each control gain variation.…”