Research On Synchronous Control Technology Of Three-Phase Photovoltaic Grid-connected Inverter

In recent years, with the fast development of global economic and the increasing population, energy shortage and environmental pollution became the difficulties faced by the world. The development and use of new green energy must be the trend, photovoltaic power generation will be dominant in the field of new energy, because of its green, clean, non-polluting, which is the most high-grade alternative. The core of energy conversion and control in a power generation system is a three-phase photovoltaic grid-connected inverter. It becomes a research hotspot that how to change the DC power generated by the PV array into the same frequency, same phase, same amplitude three-phase AC in the grid.This paper based on the three-phase photovoltaic grid-connected inverter control system, regards the synchronism control technology in photovoltaic inverter as an object to study. The mostly control form is the current or voltage to achieve synchronous in domestic and foreign, but in recent years, with the improvement in grid power rating of the inverter, the traditional control strategy slightly lacking in terms of dynamic performance, then the paper uses a new virtual flux oriented direct power hysteresis control strategy, regards the instantaneous active and reactive power as the parameters to be controlled for the closed-loop control of the power, gets fast power control response, and the introduction of improved virtual flux observer precisely targets the phase and frequency of the grid voltage, achieves the synchronous operation in unity power factor of the grid-inverter. For the problems of island protection, considering the anti-island strategy based on Sandia-frequency shift, and gives a simulation model based on the Sandia-frequency shift method in S-function, verifies its advantages are fast detecting island, simple control thought, little NDZ. Regarding TMS320F2407as the core of control, building simulation models of the system and15kW experimental prototype, tracking the fast effect of the virtual flux oriented and direct power hysteresis control through static and dynamic simulation.The three-phase PV inverter grid synchronous control system designed in this paper achieves high dynamic performances of decoupling of active and reactive power control and accurate orientation, the control structure is simple, robustness is well.