Transient Angle Stability of Inverters Equipped with Robust Droop Control

Transient angle stability of inverters equipped with the robust droop controller is investigated in this work. At first, the conditions on the control references to guarantee the existence of a feasible post-disturbance operating point are derived. Then, the post-disturbance equilibrium points are found and their stability properties are characterized. Furthermore, the attraction regions of the stable equilibrium points are accurately depicted by calculating the stable and unstable manifolds of the surrounding unstable equilibrium points, which presents an explanation to system transient stability. Finally, the transient control considerations are provided to help the inverter ride-through the disturbance and maintain its stability characteristics. It is shown that the transient angle stability is not a serious problem for droop controlled inverters with proper control settings.