Research Of Photovoltaic Power Generation System Modeling And Its Application

With the depletion of fossil energy and the aggravation of environmental pollution, it is imperative to develop and utilize new energy resources. The solar energy is widely used as an important part of new energy sources. The grid-connected photovoltaic system model is the basis of power system planning, stability analysis and control. This thesis focused on the modeling method and application of grid-connected photovoltaic power generation system.The main research content are as follows:The grid-connected photovoltaic system accesses the power system as a independent unit,and its modeling idea should be similar to the traditional rotating magnetic field modeling,therefore, this thesis aimed at achieving PQ power decoupling in the process and establishing integrated photovoltaic system static model according to the three phase single stage grid-connected photovoltaic system which was divided into DC part and AC part. For the DC part, we adopted way of derivative extremum in the mathematical filed and considered the MPPT control. The active power output model of photovoltaic power generation system was established on the basis of in depth study and analysis of the classical mathematical model of photovoltaic cells. For the AC part, the reactive power output model of the photovoltaic power generation system was established by using the state space averaging method and considering the power transmission characteristics of inductance capacitance and the switching characteristics of inverters. We have discussed the restricted conditions of the active and reactive power output of photovoltaic power generation system. The accuracy of the model was verified by building classic three phase single stage photovoltaic grid-connected system and comparing the output curve of the simulation model with the calculated data of the model.In terms of application, it was showed that the two models had a certain similarity by comparing photovoltaic power generation system model with the traditional synchronous generator. Therefore, the theory and algorithm of traditional power grid can be applied to the analysis of the photovoltaic power generation system. Integrating the model into the power flow calculation of power system, the law of power distribution and the change of network loss of power supply network after the load side is incorporated into the photovoltaic source is analyzed by IEEE14 node flow calculation under the conditions of grid connected. Results showed that the photovoltaic power generation system is beneficial to optimize the structure of power grid and reduce the network loss.