An Improved Dual-Loop Feedforward Control Method for the Enhancing Stability of Grid-Connected PV and Energy Storage System Under Weak Grids

Although the stability of grid-connected photovoltaics (PV) and energy storage systems under weak grids has been widely researched, classical improvement methods focus more on suppressing harmonics introduced by phase-locked loop (PLL). Furthermore, current distortion caused DC voltage is difficult to be eliminated. In this study, based hybrid system battery-supercapacitor, a dual-loop compensation method proposed. First, small-signal model output impedance matrix are built in d-q axis. Second, for different disturbance loops, power feedforward proposed suppress controller (DVC). addition, PLL proposed, which can reduce perturbations revise improve stability. Finally, frequency characteristic analysis hardware-in-the-loop (HIL) simulation results show that control effectively grids.