Simulation of Three-Phase Photovoltaic Grid-Connected Inverter Systems

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Simulation and Implementation of Photovoltaic Grid-Connected Inverter Systems

In renewable energy applications, grid-tied control of photovoltaic inverters represents a core component. System simulations enable validation of dynamic response characteristics, harmonic suppression capabilities, and grid synchronization accuracy. A typical three-phase grid-connected system comprises photovoltaic arrays, DC-DC boost converters, three-phase full-bridge inverters, and LCL filter networks, with the primary challenges lying in achieving unity power factor grid connection and robust disturbance rejection control.

Advantages of IMC-PID Parameter Tuning Traditional PID controllers face cumbersome parameter tuning challenges in grid current control applications. However, Internal Model Control (IMC)-based PID design directly derives proportional and integral coefficients through mathematical modeling, significantly enhancing dynamic performance. The IMC-PID approach models the inverter as a first-order lag element and calculates parameters using pole-zero cancellation principles, thereby providing stronger robustness against grid impedance variations.

Embedded Implementation with STM32 At the hardware level, STM32 series MCUs are commonly employed for real-time control applications. Their timer modules generate precise PWM waveforms to drive inverter bridge arms, while ADC modules synchronously sample grid voltages for phase-locked loop (PLL) implementation. When integrating additional functions like MP3 playback (as mentioned in extended applications), careful interrupt priority allocation is crucial to prevent grid control tasks from being blocked by audio decoding processes.

Key Simulation Verification Points Grid Synchronization: Implement software phase-locked loops (SPLL) or second-order generalized integrators (SOGI) for phase tracking; LCL Resonance Suppression: Incorporate capacitor current feedback or active damping algorithms; Low Voltage Ride-Through: Simulate inverter reactive power support capabilities during grid voltage sags.

When building models using MATLAB/Simulink or PLECS, it is recommended to progressively validate DC-AC conversion efficiency, total harmonic distortion (THD), and system stability under sudden load switching conditions. Code implementation typically involves configuring PWM generation registers, implementing Clarke/Park transformations for dq-frame control, and designing digital filters for harmonic analysis.