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How to solve algebraic loop error??

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Vidya
Vidya on 23 Nov 2012
Commented: Malaiyappan M on 17 Aug 2020
Hii....I came across this error while making a model..
Simulink cannot solve the algebraic loop containing 'trial_3/PV panel/PV module' at time 0.0 using the TrustRegion-based algorithm due to one of the following reasons: the model is ill-defined i.e., the system equations do not have a solution; or the nonlinear equation solver failed to converge due to numerical issues. To rule out solver convergence as the cause of this error, either a) switch to LineSearch-based algorithm using set_param('trial_3','AlgebraicLoopSolver','LineSearch') b) reducing the VariableStepDiscrete solver RelTol parameter so that the solver takes smaller time steps. If the error persists in spite of the above changes, then the model is likely ill-defined and requires modification.
I am using coding to make photovoltaic panel and MPPT P&O algorithm.
Please help me to solve this error.
  4 Comments
Malaiyappan M
Malaiyappan M on 17 Aug 2020
in MPPT Buck/Boost Converer try adjust the Inductor Value to resolve this error

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Accepted Answer

Azzi Abdelmalek
Azzi Abdelmalek on 23 Nov 2012
Edited: Azzi Abdelmalek on 23 Nov 2012
Algebraic loop occurs often, when you have a feedback through a constant block or equivalent, which means your signal y(t0)=constant * y(t0) , you should have y(t0+1)=constant*y(t0) which you can get with a unit delay block
  15 Comments
NING XUE
NING XUE on 10 Mar 2020
Simulink cannot solve the algebraic loop containing 'partial_shading_conditions2/PV_SERIES2/Subsystem/Divide2' at time 0.039814999999999996 using the LineSearch-based algorithm due to one of the following reasons: the model is ill-defined i.e., the system equations do not have a solution; or the nonlinear equation solver failed to converge due to numerical issues. To rule out solver convergence as the cause of this error, either a) switch to TrustRegion-based algorithm using set_param('partial_shading_conditions2','AlgebraicLoopSolver','TrustRegion') b) reducing the VariableStepDiscrete solver RelTol parameter so that the solver takes smaller time steps. If the error persists in spite of the above changes, then the model is likely ill-defined and requires modification.
The same issue,but I have place the unit delay before the feedback,can't solve this problem
can you help me?

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More Answers (4)


Kalyani Dhawad
Kalyani Dhawad on 6 Sep 2018
I have same problem in pv system

Ahmed
Ahmed on 19 Jun 2019
I've faced the same problem before, it can be solved by adding a unit delay block and type "set_param('trial_3','AlgebraicLoopSolver','LineSearch') " in the command prombit window of MATLAB.
  2 Comments
Akash maheshwari
Akash maheshwari on 3 Oct 2019
can you pleasse explain set_param('trial_3','AlgebraicLoopSolver','LineSearch'). i did that in my matlab command window but window show me that algebraic loop parameter did not found.

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