Algebraic loop error in PV panels (in filter block)

Question

Jirada Gosumbonggot 2018-8-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/416064-algebraic-loop-error-in-pv-panels-in-filter-block

回答： Gert Kruger 2019-6-28

Hello

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

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Naman Chaturvedi 2018-8-27

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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Answer 1

Gert Kruger 2019-6-28

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https://ww2.mathworks.cn/matlabcentral/answers/416064-algebraic-loop-error-in-pv-panels-in-filter-block#answer_381183

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:

https://www.mathworks.com/matlabcentral/fileexchange/71682-pv-array-with-algebraic-loop-broken

The proposed solution has been tested.

Kind regards,

Gert