Research On Key Technology Based On Current Source Inverter Photovoltaic Grid-connected Generation System

Along with the society develops, newable energy has been attracted much attention. Solar energy, as the clean energy with the portrait of non-pollution and infinite source, will be more focused.Inverter is the core component of PV(photovoltaic, PV) generation system. Traditional inverter takes the topology of VSI. This topology needs extra voltage transform circuit to realize grid-connected generation. CSI itself has the character of boosting voltage, so additional circuit is not necessary.Mathematical models of three phase CSI PV generation system are built in different frames. Modeling results in dq frame is comparatively complicated. The model in αβ frame has no coupling and is relatively simpler. Modulation strategy is studied in the second chapter and the principle is discussed as well.Model and simulation of the PV battery are built. Compared with MPPT used in VSI, due to the issue that grid-connected current is likely out of control and the instantaneous power drop on the right side of MPP under CSI control strategy, the perturbation and observation resistance MPPT is studied.DC link inductor and AC side CL filter are designed. CL filter has the inherent problem of resonant peak, so passive damping is adopted to reduce the resonance peak. Because of passive damping losses, this thesis introduces capacitor voltage feedback active damping method and designs the parameters. Simulation results show the effectiveness and correctness of CL filter design and active damping strategy.Double closed-loop control strategy for three phase CSI PV generation system is studied in two phase synchronous rotating frame. Double closed-loop consists of DC current outer-loop and AC current inner-loop. The controller parameters of inner-loop are designed in continuous time domain and discrete time domain. Stability of the system is testified under the designed parameters. Simulation results verify the correctness of the parameter design.At last,a 1kW experimental platform is built. The hardware circuits and softwares are developed. Experiments are carried out to testify the researches in this paper based on all the theoretical analysis. Experimental results verify the validness of theoretical derivation.