Research On The Seamless Transfer Control Strategy Of PV Generation System

With the consumption of the traditional fossil, people pay more attention to environmental problems, solar and clean energy are more and more popular. In order to make the full use of new energy, the seamless transfer between grid-connected and islanding modes is the precondition.This paper sets up photovoltaic(PV) generation system based on voltage-control inverter, the topology structure of the inverter and its parameters are designed, and its mathematical model is established. Then it analyzed the output of the amplitude and frequency characteristics of the no-load case. Because of the amplitude and frequency drop problem on the load case, accurate compensation is given to reference value based on virtual impedance power loss.There is bad effect between the frequency regulation and the phase angle regulation in the traditional synchronous control. This paper gives two kinds of self-synchronous grid-connection scheme, frequency regulation and phase angle difference regulation, which all make the traditional frequency regulation and the phase angle regulation unify. And the synchronous detection circuit not only provides the grid-connected signal, but also participates in the synchronous adjustment. The simulation and experiment results are presented to validate the effectiveness of the proposed control scheme.Based on the voltage-control inverter, it gives two kinds active islanding detection scheme, active amplitude perturbation method and the active frequency perturbation method, it adds direct perturbation to the output voltage and frequency.There is power decoupling problem in the low voltage distribution network. In this paper, it’s solved by the design of the virtual impedance. This paper achieves seamless transfer by ensure the continuity of the reference signals, and its mathematical model is established. The simulation is given on the light load and overload, the simulation results coincide with theoretical derivation.