Analysis On Abnormal Disconnection Of Large Scale DFIG-Based Wind Farm

Wind power is a particular power, and we wish to enlarge the scale of the wind power based on the environment protection and the utilization of the renewable energy. But the characteristics of the wind power are threatens to the safety and steady operation and the power quality of power system. With the rapidly increasing of grid-connected wind generation capacity, the influence of large-scale access of the wind power to grid operation is becoming more and more serious. But the events of large-scale doubly-fed type wind farm toke off nets brought some adverse impacts on the power system in recent years. Therefore, to analyze the different characteristics between doubly-fed induction generators and the conventional thermal power unit while taking off nets, and bring what kind of impact for the grid, is of great significance to achieve the safe and stable operation of the grid.For the problem that large-scale doubly-fed type wind farm taking off nets to bring adverse impacts on the power system, in this paper, a corresponding mathematical model was established for the phenomenon that the main protection of doubly-fed type wind generator crowbar protection movement input, before doubly-fed wind generators taking off nets, because crowbar protection movement is far more quickly than the stator circuit switching action , doubly-fed induction wind generators circuit structure or its excitation power get changed, making the unit have a short state of rat trap asynchronous running before taking off nets .In PSCAD/EMTDC simulation platform, a simulation model was established for that grid-connected doubly-fed induction wind generator is induced an abnormal off nets by crowbar protection movement. It also has a simulation to the characteristic of taking off nets for doubly-fed induction wind generator on different operation conditions. And to understand the doubly-fed induction wind generator deeply.Finally, this article mainly analyzes the wind generator and power system exchange energy in the process of crowbar protection movement induces generator to take off nets abnormally, and the influence on voltage, when absorb reactive power from grid. Through example and simulation results, it shows the influence of large-scale doubly-fed type wind farm to the reactive power of grid at off nets.