Research On The General Model Of Grid Connected Converter For New Energy Power Generation Systems

The continuous depletion of traditional energy and the brought pollution problems have become a hot topic today, while electricity is an important driving force for economic and social development. Main countries all over the world pay more and more attention to new power energy development and its utilization. Different new energy power generation systems are connected to the grid in different ways, like AC/DC, AC-DC-AC. The paper focuses on the study of the grid-connected links in the new energy power generation systems, trying to find out the similarities of different types of new energy power generation systems in the grid-connected links. The goal of this paper is to take advantage of the similarities to build a general grid-connected model which is fit for new energy power generation systems.After summarizing the grid-connected structures of different new energy power generation systems, the paper focuses on the research of wind power, photovoltaic power generation and battery energy storage system; and the storage system is mainly used as complementary for wind and photovoltaic systems. Electromagnetic transient mathematical models for wind power, photovoltaic power generation and energy storage power system are built; and simulations for these models based on Matlab/Simulink software are performed. The simulation results of the related parameters and designed values are in good agreement, which can reflect the correctness of the established model.Based on analyzing the three kinds of new energy power generation system model, according to the idea of the switching, the general grid-connected model is built, which is suitable for wind, solar and of energy storage system. When different new energy source is connected or different control strategies are employed, one can achieve different goals by control the switch. In order to prove the correction of the model, two examples are given: PV-energy storage hybrid system and wind-PV-energy storage hybrid system. The simulation results in Matlab/Simulink software are in agreement with the results of single new energy power generations system, which shows that the general grid-connected model can realize the grid-connected requirements of new energy power generation systems.Further, since only input and output state, but not the internal detailed models of power electronic devices, are mainly considered during the simulation studies on large scale power system, and also simulation time is often longer for the electromagnetic transient model, the dissertation puts forward the general grid-connected model for the electromechanical transient. In order to explore the electromechanical transient model, an energy storage power generation system of the "source with inverter" model is built and simulated in the DIgSILENT software. The simulation results can track the control target parameters quickly, which shows the fast response and feasibility of applying electromechanical transient model as the general grid-connected model.