Analytical Simulation Of Permanent Magnet Direct Drive Wind Power Generation System

In the permanent magnet direct drive wind power generation system,both the machine side and the grid side converter are composed of self-commutated power electronic devices.Due to the frequent turn-on and turn-off of the device,the system is running in a variety of asymmetric and symmetric complex transient process.The simulation of the whole system needs to be completed in the system at every moment of transient accumulation by the traditional numerical method.But in the face of increasing scale and large numbers of converter wind power generation system,the numerical simulation speed is very slow.Aiming at the permanent magnet synchronous generator-rectifier system model in permanent magnet direct drive wind power generation system,this thesis uses analytic method to solve the complex transient model of the system,which provides a faster calculation method for the simulation of permanent magnet direct drive wind power generation system to complete the analytical simulation under the specific running condition and study the fastness of its simulation calculation.First of all,the mathematical models and transformations of permanent magnet synchronous motor(PMSM)in three-phase stationary coordinate system,synchronous rotation coordinate system and space vector representation are introduced respectively.The mathematical model of the permanent magnet synchronous motor is reduced by the space vector representation,and its transient mathematical model is calculated by analytic method and numerical method respectively,and the characteristics of the two methods are analyzed respectively.Secondly,according to the different expression of switching time and the order of the system,the method of generating SPWM pulses from different modulation frequency and carrier frequency is obtained.And in the M file programming verification simulation,the follow-up work is provided the basis.Then,through the establishment of permanent magnet synchronous generator-rectifier system mathematical model,respectively,by analytic method and numerical method to be applied to the system under a variety of complex transient current expression,to achieve two different methods to solve the system running process in the complex transient problem.At last,programme in M file according to the analytical method and the numerical method to the solution of the system,and combine with the system switching time and order.The analytic simulation and numerical simulation of the system under certain operating conditions are realized by calculating the transient of each switch state of the system.Under the same condition,the same model is built inSimulink simulation environment.Simulink simulation,analytic simulation,fourth-order Runge-Kutta method and improved Euler method are simulated in the same conditions and timed.The results show that the time cost by analytic simulation is the least,which reflects the speed advantage of using the analytic method to calculate the complex transient of the system.