An Unconstrained Voltage Support Scheme for Distributed Generation Connected to Resistive-Inductive Grid under Unbalanced Conditions

During the grid faults, the large distributed generation (DG) is required to support the voltage at the point of common coupling (PCC), for a specified duration, as per the grid code. The recent research trend is toward the voltage support for the resistive-inductive grid. This paper proposes a novel unconstrained voltage support scheme (VSS) for the resistive-inductive grid, under voltage imbalance. The existing voltage support schemes for the resistive-inductive grid impose certain constraints on the proportion of active and reactive components of currents that adversely affect the performance. The proposed VSS does not impose such constraints and provides enough compensation when available active power is not sufficient. It also provides the required compensation with much less active power curtailment when available active power is high. The reference current expressions for the proposed VSS are analytically derived. The simulation results demonstrate that the proposed VSS achieves its objectives.