Reseach And Implementation Of Pv Inverter Network Control System

In recent years, development and optimized utilization of new energy has aroused great attention around the world with the worsening of the world energy crisis. PV inverter is a significant distributed generation that utilizes new energy, and is an important part of microgrid, so the research of PV inverter’s network control system is widespread concerned. This paper designs and analyzes each department of a three-phase grid-connected PV inverter control system in order to improve the stability, dynamic performance, steady-state performance and improve the output power quality of the network system.Firstly, the paper analyzes the PV inverter grid principle. On the basis of grid principle, the SVPWM switch control technology is introduced. The paper elaborates theoretical foundation of the switch control technology, exactly derives the coordinate transformation process of three-phase alternating current and three-phase AC voltage from the three-phase stationary coordinate system to the two-phase revolving coordinate system. Studies the reference voltage’s composite method from the basic vector synthesis, and briefly introduces the DSP implementation of the SVPWM waves, achieves the current control from the three-phase alternating current to a DC control current.Secondly, the paper builds the system model based on the grid model and the SVPWM switch control method. Because active current and reactive current coupling control phenomenon caused by the coordinate transformation, the decoupling design been proposed. The paper designs the grid voltage disturbance compensation link to eliminate the effect of grid voltage on the system steady-state error, introduces PI controller and analyzes the role of PI control principle.Third,This paper analyzes the steady state, dynamic performance and stability performance of the grid control system in detail. The paper compares the affect from the variations of the PI parameters and the system hardware parameters on system performance. Because the PI controller can’t eliminate steady-state error theoretically, the paper brings in the Repeat control, analyzes the Repetitive control theory and changes the structure of the Repetitive control theory based on this design. The paper designs the Composite control with the Repeat control and the PI control.Finally, the paper builds the MATLAB simulation model of the system and through the simulation results verifies the correctness of each module of the system. The system design is tested on the hardware platform and the test results are analyzed. The test results show that the harmonic output power factor is 1.8%, the power factor is 0.99 when the system working at full power 1500 W. The experimental results show that the theoretical analysis of the foregoing is correct, and the control system can effectively control the grid current.