A multi-mode operation control strategy for flexible microgrid based on sliding-mode direct voltage and hierarchical...

Area of Science:

• Electrical Engineering
• Power Systems Engineering
• Control Systems

Background:

• Flexible microgrids (MGs) face challenges in multi-mode operation and transient stability.
• Effective control strategies are crucial for reliable MG performance and grid integration.

Purpose of the Study:

• To propose a multi-mode operation control strategy for flexible MGs using a three-layer hierarchical structure.
• To enhance system disturbance-rejection and power sharing accuracy.
• To achieve seamless transitions between islanded and grid-connected modes with improved transient performance.

Main Methods:

• A three-layer hierarchical control structure comprising autonomous, cooperative, and scheduling controllers.
• An adaptive sliding-mode direct voltage loop for disturbance rejection.
• An improved droop power loop using virtual negative impedance for accurate power sharing.
• Secondary voltage/frequency control and phase synchronization for grid connection.

Main Results:

• The proposed control scheme enables seamless transitions from islanded to grid-connected modes.
• Demonstrates good transient performance and improved power quality.
• Enhances load power sharing accuracy between parallel voltage source inverters (VSIs).

Conclusions:

• The novel hierarchical control strategy effectively addresses multi-mode operation and transient stability issues in flexible MGs.
• The proposed methods improve system robustness, power sharing accuracy, and power quality.
• Validated through theoretical analysis and simulation, the strategy offers a reliable solution for flexible MG operation.