Passivity-Based Control for the Stability of Grid-Forming Multi-inverter Power Stations

Existing grid-connected inverters encounter stability issues when facing nonlinear changes in the grid, and current solutions struggle to manage complex grid environments effectively. We propose a passivity-based control strategy to enhance the stability and dynamic performance of grid-forming multi-inverter power stations and address these challenges. The inner loop designed from the perspective of energy reshaping, ensures the stability of the inverter’s output. The outer loop is designed with differential passivity, significantly enhances the responsiveness to disturbances, and ensures power sharing and phase synchronization without the need for communication when multiple inverters operate in parallel. The nonlinear disturbance observer estimates the nonlinear disturbances at the grid connection point and feeds this information into the inner loop for parameter compensation. We demonstrate the passivity of the overall controller with Lyapunov-based stability criteria. This ensures that the inverters within a power station can operate stably under nonlinear and random changes in grid structure and parameters. Finally, experimental and simulation results verify that the proposed method ensures inverter stability under nonlinear and random disturbances, significantly suppressing oscillations while maintaining operation without steady-state errors. This work provides a feasible solution for enhancing inverter stability in power stations, contributing to the reliable integration of renewable energy.