MATLAB Answers


Algebraic loop error in PV panels (in filter block)

Asked by Jirada Gosumbonggot on 24 Aug 2018
Latest activity Answered by Gert Kruger on 28 Jun 2019
I tried use PV array block from simulink to program MPPT. But I have a problem during simulation which is the algebraic loop in the filter block inside PV block.
Here's the error message I received
I also tried to put the unit delay block before the sum, but when I tried to simulate the system cannot find the filter block and could not run. I also tried to reduce the tolerance but it seems not working.
Any suggestion for me? Thank you so much

  1 Comment

I tried implementing the model and it worked fine for me. Can you please share your model or the inputs of the model.

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1 Answer

Answer by Gert Kruger on 28 Jun 2019

The reason why there is an algebraic loop:
The V-Filter and I-Filter in the model, for the computation of Vd, is supposed to break the algbraic loop. Vd which is dependent on the model output is fed-back to the model inputs which would have caused an algebraic loop if the filters were not present. The presence of the algebraic loop indicates that the V-Filter and I-Filter implementation probably has an unintended direct feed-through at some point during the simulation.
Some suggest to add a unit delay, but this forces the model to be a mixed simulation problem, even if the rest of the model consist out of continuous state models. Secondly, what is an appropriate sample time for the unit delay?
Download a PV panel model with the algebraic loop fixed at:
The proposed solution has been tested.
Kind regards,


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