A new model reduction method based PBC control for grid-connected inverter with LCL-filter.

Area of Science:

• Electrical Engineering
• Control Systems
• Power Electronics

Background:

• Conventional passivity-based control (PBC) for LCL-filtered grid-connected inverters (GCI) suffers from limited control bandwidth due to time delays, leading to poor dynamic performance, particularly under weak grid conditions.
• This limitation hinders the efficiency and stability of grid-connected power systems.

Purpose of the Study:

• To propose a novel passivity-based control (PBC) method, termed proportional PBC (P-PBC), to enhance the closed-loop bandwidth and improve dynamic performance of LCL-filtered grid-connected inverters (GCI).
• To reduce sensor requirements and enhance system reliability through the integration of a state observer.

Main Methods:

• A new passivity-based control (PBC) strategy (P-PBC) is developed by adjusting the feedback proportional coefficient between grid-side and inverter-side currents to increase closed-loop bandwidth.
• A state observer is incorporated to estimate system states, thereby reducing the number of required sensors.
• Experimental validation is performed on a 110 V/50 Hz/3 kW three-phase system using a dSPACE DS1202 platform.

Main Results:

• The proposed P-PBC method successfully increases the closed-loop bandwidth of the LCL-filtered GCI system.
• Improved dynamic performance is achieved, especially under challenging weak grid conditions.
• The use of a state observer effectively reduces sensor count and associated costs without compromising reliability.

Conclusions:

• The proposed P-PBC method offers a significant improvement over conventional PBC for LCL-filtered GCIs, providing enhanced dynamic response and robustness.
• The integration of a state observer presents a cost-effective and reliable solution for sensor reduction in these systems.