Research On VSVC Method And MPPT Of Photovoltaic Grid-connected System

In this dissertation, the theory of VSVC is been researched in order to avoid the disadvantage of the traditional VSCC method. Because it can't improve the electric power quality of Grid so as can not to operate independently or operate in a Micro-grid. The output end active and inactive electric power can be adusted by change the phase and the amplitude accord to the droop method theory. It can operate in Micro-grid system or operate independently because it controls the voltage directly to get rid of the reliance on the voltage of Grid.The feasibility of VSVC strategy and the system characteristics are validated with MATLAB computer simulation and the results are satisfactory.1. The output power can be quickly adjusted by changing the phase and the amplitude of output end accod with the load in the system with Voltage-control Strategy.2. The power quality of Grid can be improved by support active and inactivepower when it parralell with Grid and also adapt to the load change when run independently.3. The output voltage will have an impulse when the inverter disconnect withthe Grid.4. Because of its good dynamic and static characteristics, this system canapply in various situations.The traditional MPPT method has disadvantages in being influenced by temperature severely, has the excessive power loss or the breakdown of DC link-voltage. So, this dissertation put forward a database-based MPPT control method to get red of these shortcomings.