PQ Control Simulation in Grid-Connected Microgrid Mode

PQ control simulation in grid-connected microgrid mode serves as an effective method for modeling power control strategies when a microgrid interfaces with the main power grid. PQ control (active power P and reactive power Q control) represents a common operational mode in microgrid systems, particularly applicable during grid-connected operation where the microgrid must maintain predetermined active and reactive power outputs. The following key aspects characterize PQ control simulation:

Control Objective: PQ control aims to ensure distributed energy resources (such as photovoltaic systems, wind turbines, energy storage systems) operate according to specified active power (P) and reactive power (Q) reference values. This maintains system stability while meeting the main grid's power requirements. Implementation typically involves setting reference values through control algorithms that calculate required current outputs.

Control Architecture: The simulation typically employs a dual-loop control structure, with an inner loop for current regulation (using PI controllers) and an outer loop for power adjustment. The outer loop calculates current references based on power setpoints, while the inner loop controls inverter output current to track these references. Code implementation often features separate PI controller modules for dq-axis current regulation with anti-windup protection.

Simulation Components: - Reference Power Setting: Establishing P and Q references based on microgrid operational requirements or dispatch commands, often implemented through lookup tables or real-time communication interfaces. - Power Calculation Module: Real-time monitoring of microgrid output P and Q values with continuous comparison against reference values, typically using instantaneous power theory calculations. - Current Control Strategy: Closed-loop regulation ensuring rapid and accurate power tracking through PWM signal generation and inverter switching control algorithms.

Simulation Verification: Models can be developed using power system simulation software like MATLAB/Simulink or PSCAD to evaluate dynamic response characteristics, power tracking accuracy, and disturbance rejection capabilities. Key implementation aspects include proper discretization of control algorithms, synchronization with grid voltage through PLL circuits, and harmonic analysis modules.

Application Scenarios: PQ control demonstrates significant importance in scenarios involving microgrid participation in main grid power regulation, renewable energy fluctuation smoothing, and frequency/voltage support services. The control algorithm can be enhanced with adaptive gain scheduling for varying operating conditions.

Through simulation, control parameters can be optimized to improve microgrid stability and power quality in grid-connected mode, providing theoretical foundation for practical engineering applications. Typical optimization approaches include particle swarm optimization for PI gains and sensitivity analysis for parameter robustness.