Research On Single-phase Photovoltaic Grid Connected Control Technology Based On Second Order Generalized Integrator

With the development of grid connected generation technology such as photovoltaic, wind power and other renewable energy sources. Distributed energy grid connected generation as an effective way of generating, play a significant role in reducing environmental pollution, improve energy efficiency, to meet load growth and other aspects of demand. The grid-connected inverters as an interface of grid and distributed energy generation systems, it is important to research its control Strategy. It is inconvenient for traditional single-phase grid-connected inverter to implement active and reactive power independently control. In this paper, SOGI is used to reconstruct two orthogonal fundamental current signal. Achieve decomposition of active and reactive components of fundamental current under synchronously rotating coordinate system. And then realize the decoupling control of active and reactive components of fundamental current; realizing observation and control of output current harmonics at single-phase grid-connected inverter by using reconstructed fundamental current. And verify the correctness and effectiveness of the control strategy by simulation.Firstly, this paper gives a brief narrative of the research background and significance of the subject. Analyzing single phase photovoltaic grid-connected system at home and abroad development situation and trends. Introduce the topology and the main phase inverter control strategy of single-phase grid-connected inverter.Secondly, Introduce the model of single-phase grid-connected inverter. Analyzing the principle of single phase photovoltaic grid-connected system under the synchronous coordinate system. Derivation of the system model of single-phase grid-connected inverter under the stationary frame and the synchronous coordinate system. To determine the selection of the main circuit components through analyzing the principle of the system. On the basis of, by analyzing the principle of quadrature signal generator. Reconstruct two orthogonal fundamental current signal by SOGI, and make a research of construct two-phase and quadrature signal by simulation. The simulation results show that the method of constructing orthogonal signals is not only with fast dynamic response speed, but also not sensitive by harmonics of the input signal. It has better robustness; realizing observation and control of output current harmonics at single-phase grid-connected inverter by using reconstructed fundamental current. The simulation results show that the method of harmonic current detection achieve a separation of the higher harmonic components and inhibition. Improve the power quality of single-phase grid-connected system.Finally, combine of classic PI control and vector control technology. Using Matlab /Simulink to build a simulation model of two-stage and non-isolated single-phase grid-connected inverter. Verify the validity and correctness of the above control strategy by simulation analysis and research.