A New Virtual Inertial Strategy for Andronov–Hopf Oscillator Based Grid-Forming Inverters

Inertia plays a vital role in maintaining the frequency stability of the power system. Insufficient inertia will deteriorate the lowest point of frequency and damage the stability and reliability of the power system. The Andronov–Hopf oscillator (AHO) control is a grid-forming (GFM) control based on instantaneous current feedback, which has superior self-synchronization, accurate power sharing, and low harmonics. However, the similar nonlinear droop characteristic embedded in the dynamic response of AHO cannot provide inertia to the power system. In this article, a modified AHO embedded with virtual inertial (VI) control is proposed, which provides virtual inertia for the frequency response by adding the quasi-resonant controller to the current input loop of AHO. With a well-designed structure and parameters of the VI controller, the modified AHO controller can effectively provide a suitable inertia and damping ratio for the power system. The experimental results show that compared with the traditional AHO control, the modified AHO control provides enough inertia to alleviate the rate of change of frequency of the power system in the island mode while having a low power overshoot in the grid-connected mode.