Research Of Low Voltage Ride Through Operation Of Doubly Fed Induction Generator Based On Finite Element Calculation

With the rapid development of the world economy, global demand for energy has also increasingly strongly. By virtue of endless, clean and renewable advantage, the wind becomes the direction of the current hot spot for researchers. Expansion of wind power installed capacity of wind power makes the power supply status gradually improved, and double-fed wind turbine frequent incidents of off-grid will give power grid reliability a very bad influence. Therefore, the modern society made a high demand of the performance of the work of wind turbines, especially in the voltage drop condition, wind turbine is at the request of continuing to supply capacity. In order to make more effective use of wind energy and improve the stability of wind power systems, many countries in the world have invested a lot of manpower and material resources. According to the motor design theory, design of a 1.5MW double-fed generator, the establishment of a finite element model is done, and the corresponding dynamic simulation is studied for different faults and working conditions.Firstly, the characteristics of doubly-fed wind power generation system, the working principle of a state is with a detailed analysis, the mathematical model, and working conditions were studied with VSCF generation capacity .Its energy flow relationships between conditions was analyzed.Then by reference of motor design theory and conventional motor design approach, a 1.5MW double-fed wind turbine is designed, according to its characteristics, the main dimensions, structure and electromagnetic parameters is determined, so the preliminary design comes out. And the base model of the generator is built in Ansoft Rmxprt simulation analysis software, based on magnetic equivalent circuit analysis, the simulation data of generators is got, and the further design improvements were done according to the results of the simulation. Using Ansoft Maxwell finite element software to build its finite element model to study the distribution of the parameters and electromagnetic under its rated load condition and no-load state and further analysis of its combination flux density in the harmonic content in Matlab. According to the simulation results, the reasonableness and accuracy of the design is verified and it becomes a research based model of the short-circuit fault transient characteristics.After that, according to the mathematical model of doubly-fed generator, its voltage drop under transient fault response is analyzed, the external circuit is completed based on the finite element model has been designed, importing finite element model to simulate. The transient characteristics of three-phase short circuit fault and two-phase short circuit fault phase were studied, the intensity of the impact of two failures of the generator was compared. Based on researching of Crowbar circuit protection principles and their importance for the realization of low voltage ride through, Crowbar circuit protection for generator phase short circuit fault transient response under a different resistance were analyzed and studied. While the different effects of switching time on the Crowbar circuit were compared, it comes to a conclusion that Crowbar circuit protection can be used as a mean s to achieve low- voltage crossing.Experimental results of doubly-fed generator finite element simulation model established in this paper are accurate and can be a certain theoretical reference value to ensure stable operation of the system.