Why do I get error when running my Simulink model? How do I reduce the fixed step size and what is meant by tightening the error tolerances?

Hi..Can anyone help me in resolving the error i'm getting while running the model? The simulink model is developed in Matlab R2021a version. The model is Grid connected PV system. In this system three controllers are developed i.e, DC Voltage controller, Inverter current controller and MPPT Controller. Integrator blocks are used by multiplying with some gain blocks in this controllers. After running the entire model it is showing error at the integrator block as shown below.

"Derivative of state '1' in block 'PV_GridconnectedSystem/Integrator1' at time 3.7333333333333331E-5 is not finite. The simulation will be stopped. There may be a singularity in the solution. If not, try reducing the step size (either by reducing the fixed step size or by tightening the error tolerances)"

Why do I get this type of error and how to fix it?

Answer 1

[Shang-Chuan Lee]

Hello BHAGYA LAKSHMI,

The error may be due to a model instability. One way to remove the error is to open the dialog box of the 'Integrator' block, select 'Limit output' and specify an initial condition and saturation limits. Another way to further improving the model stability is through Solver Profiler which can help you visualize your model dynamics and see where they may be unstable. Using the Solver Profile is described at this link: https://www.mathworks.com/help/simulink/ug/examine-solver-behavior-using-solver-profiler.html

Hope this helps,

Shang-Chuan Lee

[BHAGYA LAKSHMI]

Thank you Shang-Chuan Lee