Transient Stability Analysis and Enhanced Control Strategy for Andronov-Hopf Oscillator Based Inverters

The Andronov-Hopf based virtual oscillator control (AHO) is a novel nonlinear grid-forming (GFM) control strategy that has better dynamic performance compared with droop and virtual synchronous generator. However, the grid voltage drop can affect the synchronization between the AHO inverter and the grid. In extreme cases, the system may lack a stable operating point, leading to transient stability issues. This paper establishes a dynamic power angle model that takes into account the voltage characteristics of the inverter. Subsequently, the influence of AHO parameters on transient stability is analysed under current unconstrained operation, and the impacts of current limitation strategy are discussed. On this basis, a transient stability enhanced control strategy for AHO inverters is proposed from the perspective of optimizing voltage characteristics and compensating power setpoints (OVCP). A small-signal model is then established to analyse the stability of the proposed strategy. Finally, simulations and hardware-in-the-loop simulations based on RT-BOX are conducted to verify the effectiveness of the proposed transient stability enhanced control strategy.