Impact of phase feed-forward control of gridforming inverters on frequency behavior in interconnected power systems

Abstract:
One promising pillar supporting the transformation of the interconnected power system is the integration of grid-forming inverters. These inverters are able to provide inertia and can therefore significantly improve frequency stability in severe fault conditions, such as system splits. By the integration of grid-forming control approaches, power system damping and inertia become parameterizable. This paper analyses the impact of grid-forming inverter approaches on the system damping when using a phase feed-forward term. For comparison, the damping effect from conventional speed droop control of synchronous generators is shown. Therefore, a small signal analysis is performed on a two-area system and the similarity of both damping methods on the overall system dynamic is demonstrated with root locus investigations. Furthermore, the effect of the phase feed-forward control on transient frequency behaviour is shown based on the transfer function. For a confirmation of the analytical findings, the step responses are compared successfully against results from a detailed EMT network simulation.