Transient stability enhancement strategy of grid-forming inverter based on adaptive q-axis voltage feedback

Purpose With the development of new power systems toward high proportion of renewable energies and high proportion of power electronic equipment, grid-forming (GFM) inverters play an important role in new power systems due to its well active support capabilities for voltage and inertia. The fault ride-through ability of GFM inverter is the foundation for guaranteeing the safety and stability of power systems. However, during fault, the large disturbances may cause the GFM inverter lose stable equilibrium point (SEP) and induce transient instability issues. To address this challenge, this paper aims to propose a transient stability enhancement strategy of GFM inverter based on adaptive q-axis voltage feedback control. Design/methodology/approach First, a transient stability analysis model of GFM inverter while considering the current limitation and q-axis voltage feedback is established, and impacts of q-axis voltage feedback on the transient stability of GFM inverter under the gird voltage sag is revealed. Inspired by this, an adaptive q-axis voltage feedback control is proposed to improve the transient stability of GFM inverter. Findings According to the voltage sag degree, the expression of adaptive q-axis voltage feedback coefficient is designed, which can adaptively change the equivalent active power reference to guarantee the existence of the SEP in the system whatever the current limitation is triggered or not. Also, since the q-axis voltage feedback coefficient is equal to zero under the normal operation, it has no impact on GFM inverter. Finally, the correctness and effectiveness of the proposed strategy are verified by the hardware-in-the-loop simulation experimental platform. Originality/value A transient stability analysis model of GFM inverter system while considering the current limitation and q-axis voltage feedback branch is established. Under the condition of short circuit fault, the influences of q-axis voltage feedback coefficient on the system’s transient stability are revealed after triggering current limitation. An adaptive coefficient of q-axis voltage feedback in GFM inverter is designed, which can adaptively change the equivalent active power reference to guarantee the existence of the SEP in the system under different grid voltage dips, and it has no effects on normal operation of GFM inverter.