discrete simulink model problem
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hello everyone, I realized a control program of a single-phase inverter connected to the grid by an LCL filter under matlab / simulink. In the continuos mode, i have got good results (grid current/voltage) , but when I converted the program to the discrete domain every thing went crasy and nothing went right. I can't find what i did wrong. Can anyone help me please?
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Jim Riggs
2018-1-10
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Although I am unable to open and view your model, a very common problem when converting from continuous to discrete is that the discrete solver will be based on a forward Euler method. This is much less precise than the higher-order continuous solvers which are commonly used. The first thing that you should try is to run the discrete model with a very small time step - about 100 times or even 1000 times smaller than you were using with the continuous model. See if this helps.
2 个评论
Meriem dardouri
2018-1-11
Jim Riggs
2018-1-11
You must apply numerical techniques to improve the accuracy of the method. in the attached paper, I show an example of implementing a generic second-order transfer function using a forward-Euler integration method compared to a second-order Runge-Kutta method. You will note that the second-order method results in significantly more complex equations. But you don't need to actually formulate the model in terms of a closed-form equation the way I did in this paper. You can numerically implement the method as described on pages 3 and 4 of the paper. This should give good performance and allow you to reduce the time step by two orders of magnitude.
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