Distributed Harmonic Power Sharing with Voltage Distortion Suppression in Islanded Microgrids Considering Non-linear Loads

In contemporary power grids or microgrids, harmonic distortion has emerged as one of the critical power quality issues for utility power grids, which has escalated especially due to the high penetration of power-electronic-converter-interfaced distributed generation (DG). This paper first illustrates the prevalent dispute revolving around the harmonic power sharing and distortion restraint, and subsequently proposes a consensus-based framework that facilitates an accurate sharing of harmonics among multi-DGs connected in parallel, with an effective suppression of the output voltage distortion. Compared with the majority of existing studies addressing the issue of voltage harmonics at the point of common coupling (PCC), our method primarily emphasizes on the output voltage distortion since the power quality requirement for certain local critical loads is often known to be high. With the help of adaptive regulation, the overall distortion produced at the output terminals of DGs can be retained within an acceptable range. The working principle of the proposed control method, which is not only easy to implement but also independent of model parameters, is further described in detail. Employing the small-signal dynamic model, the system stability and robustness are analyzed. The hardware-in-the-loop (HIL) simulations aid in determining the outcome of the proposed strategy in microgrid control.