AC Capacitor Dynamics-Based Synchronous Control for Grid-Following Operations

The growth of renewable energy generation drives an increase in power inverter integration. Grid-following inverters remain the mainstream solution for renewable energy connection due to their operational efficiency and superior compatibility with the existing grid infrastructure. However, their reliance on phase-locked loops leads to implicit synchronous inertia and damping, challenging parameter design and system stability. This article proposes a phase-locked loop-free control strategy that enables explicit and tunable synchronous characteristics for grid-following inverters. The method achieves grid synchronization via ac capacitor dynamics without relying on active power, thereby preserving the energy conversion advantages of the grid-following mode. Further analysis reveals that inverters synchronized via reactive power inherently exhibit grid-following rather than grid-forming behavior. Last, an intuitive analytical model is developed to assess the stability, with experiments and simulations validating the proposed method.