A Novel Tuning Method of Grid-Forming Inverter Voltage Control

Grid-forming inverters (GFMs) may experience instability in strong grids, often resulting from voltage control interference, particularly when multiple voltage sources are electrically close. This issue is further exacerbated when control gains are obtained under avoidable assumptions. A temporary solution is to retune control gain, yet it yields suboptimal performance. To address this, we propose a novel tuning technique for GFM control that employs a concurrent design approach for d and q axes voltage control. The proposed method also incorporates the dynamics of an equivalent grid model in the design process. The required design specifications are translated into weighting functions, formulating the H∞ minimization problem for optimal tuning. The proposed tuning method is compared against direct synthesis and symmetrical optimum methods. The comparison reveals the advantages of the proposed method in mitigating the impact of grid strength. Their performance is evaluated on 9-bus and 11-bus test systems. It is shown that the proposed approach achieves higher control bandwidth and improved stability margins compared to conventional designs.