The Study Of Photovoltaic Grid-connected Control Method And System

In the future,the main utilization of solar energy will be the grid-connected Photovoltaic system. With the development of digital signal processors (DSPs),it is possible that some advanced control strategies are applied to the grid-connected PV control system. Aiming at the features of grid-connected PV system,a kind of grid-connected control strategy is presented,which is based on the multi-variable double-loop control and synchronization phase-locked control. The multi-variable double-loop control is used for the real-time tracking,and the inherent principle error existing in the single-loop control is eliminated. The synchronization phase-locked control makes the frequency and phase of output current equal to those of utility voltage. The simulation results prove the validity of the control strategy.The factors effecting on the grid-connected ripple current are analyzed deeply. The criterions of selecting inductance L and direct current voltage Ud are presented. An output filter between the output end of inverter and the power network is added to improve the quality of output current. The design of the filter is discussed in detail.A keyboard monitoring subsystem and a communication subsystem has been developed. The keyboard monitoring subsystem based on a micro-controller AT89C52 realizes the keyboard monitoring,LCD display,parameter setting and etc. The communication subsystem performs the communication between the AT89C52 and a TMS320F240 DSP in real time.