A Robust Damping Control for Virtual Synchronous Generators Based on Energy Reshaping

Abstract

Virtual synchronous generators (VSGs) have been proved to be important means to provide the inertia for future power systems. However, it suffers the issue of active power oscillation under various disturbances. In this paper, a robust damping control is proposed to mitigate the active power oscillation by reshaping the oscillation energy of VSGs. The paper first represents the power-angle dynamics of VSGs as an equivalent circuit and thus enables the understanding of oscillations from the circuit energy. It is revealed that the active power oscillation can be comprehended as an LC resonance and the damping provided by the traditional VSG is commonly insufficient. To tackle this issue, a robust damping method is proposed using interconnection and damping assignment passivity-based control (IDA-PBC). The theory of IDA-PBC is established based on the concept of energy reshaping, which guarantees the state tracking via its intrinsic energy dissipation characteristics. The IDA-PBC, when applied to VSGs, is a combination of the disturbance compensation via feedforward channels and the deviations regulation through feedback paths. Noticeably, the disturbance compensation is achieved with the support of an extended state observer (ESO), which can accurately estimate the lumped disturbance including the grid frequency variation and the model uncertainties. A guideline on the parameter selection is also provided through Bode-plot analysis. Finally, the effectiveness and merits of the proposed method is verified by hardware in the loop-based experiments with the comparison to the state of art work.