Oscillation Suppression Strategy for Grid-Forming Energy Storage Converters in Weak Grids Based on Transient Power Compensation

As the proportion of new energy power generation in power system is increasing, insufficient rotational inertia frequently occur in the grid. Grid forming energy storage system which is built grounded on voltage source converter with flexible adjustable virtual inertia and damping, which provide active voltage and frequency support to power grid. However, oscillation often occurs when a grid forming energy storage connect to a weak system. A small-signal model is established in this paper for a grid-forming energy storage voltage source converter to analyze the relationship between inertia and damping parameters on oscillations, as well as the effect of grid short-circuit ratio on system stability margins. Then a transient power compensation-based oscillation suppression strategy for a grid forming energy storage converter is proposed to suppress oscillations by increasing the equivalent damping. Finally, transfer function modeling method is used to verify decoupling effect of the compensation parameters and frequency regulation coefficients. In addition, compensation parameters design method is given by analyzing Zero and Pole distribution. The simulation results verify the effectiveness and correctness of the proposed control strategy.