Research On Dynamic Equivalent Modeling Of Wind Farm

With the increasing depletion of fossil fuels, wind power has became a new pillar in the development of renewable energy in the world. And then, because of the increase of the capacity of wind farm and the number of wind turbine, the wind power have much more influence on the grid of power system, which brings great challenges to the research of large-scale power system. The theory of wind farm modeling has became a urgent problem must be solved. Based on the opinion above, this paper makes a series of research on wind farm dynamic equivalent using variable speed constant frequency doubly fed generator.This paper introduces the component and mathematical model of DFIG, including the aerodynamic model, shaft model, protection circuit and the mathematical model of induction generator. On the basis of this, author make a new doubly fed wind turbine model in PSCAD/EMTDC software platform. Then, the paper make the model of external characteristic curve using the new DFIG model.A simulation of characteristics of doubly fed wind turbine fault is carried out. Through the simulation using a large number of wind speed, detected that some of electrical quantities of wind turbine have polymeric phenomenon. On the base of the research above, a simulation about the equivalent of two wind turbine is carried out. By giving two typhoon machine different combinations of wind speed, we found the relationship between the equivalent error and the mean wind speed and wind speed difference. It is found that the equivalent error have certain monotonous variation when wind speed and wind speed difference changed. And then the further research shows that, to some extent, the equivalent error have a clustering effect when wind speed changes.A wind turbine clustering equivalent method for DFIG based on the error polymerization phenomena is provided, and then by using PSCAD/EMTDC simulation software, we can build a wind farm and equivalent calculation and simulation work. The result shows that the method is more accurate and useful than the conventional method of equivalent wind farm to a single wind turbine. And the further study verified that the method is robust that can suit to wind speed fluctuation and some other disturbance.