Comparison of Droop Control and Virtual Oscillator Control Realized by Andronov-Hopf Dynamics
Minghui Lu, Victor Purba, Sairaj V. Dhople, Brian Johnson
Abstract
Virtual oscillator control (VOC) is a time-domain strategy for regulating the operation of grid-forming (GFM) inverters. The premise of this method is to leverage the dynamics of nonlinear oscillator circuits to realize controllers; the time-domain nature of the resulting implementation is starkly different from classical droop control methods. This paper considers VOC realized with the dynamics of the Andronov-Hopf oscillator, a second-order nonlinear dynamical system that enables GFM inverters to be dispatched and generate low-harmonic outputs while not compromising dynamic performance. Leveraging an equilibrium analysis of the involved dynamics and small-signal models, we put forth a side-by-side comparison of dynamic performance and small-signal stability with classical droop control. The results demonstrate superior dynamic performance of VOC, and broadly, the paper furthers efforts focused on modeling and analysis of this general class of GFM controllers.