| In recent years, photovoltaic power generation industry has obtained rapid development. The inverter is a key component of the photovoltaic grid power generation system, this paper studies a kind of grid connected photovoltaic power generation system based on LCL type filter, the main contents are following:According to the system structure, this paper establishes the mathematical model of the inverter circuit and filter circuit. The power circuit is designed based on IPM and the signal processing circuit based on DSP. The power circuit using the IPM devices improves the system reliability and stability. The signal processing circuit part gives a hardware protection and fault latch module, enhances the processing ability of the system circuit fault.This paper studies the control scheme of grid connected system based on Matlab simulation platform. According to the established mathematical model, double closed loop control system is designed which the current inner loop can mainly achieve the fast tracking of the reference grid current and the voltage outer loop can improve the system of anti disturbance. The current loop control strategy which combined a PI controller with a resonant controller is given which can effectively improve the tracking effect of the system on the reference current.This paper studies the LCL filter resonance peak suppression methods, gives a kind of passive damping method of series resistance in the filter capacitor by the obvious inhibition effect. In order to improve the speed and precision of PLL system, a variable step size software phase locking method based on PI controller. Through the simulation experiments verify the feasibility of the method.This paper completes the design of software and hardware, the system of production and testing, the testing results are given complete. The experimental results prove that the design of hardware circuit and the control method of the reliability of grid connected inverter are correct. |
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