Please take a minute to review and accept our Terms of Use.
Welcome to the PLECS User Forum, where you can ask questions and receive answers from other members of the community.

Many technical questions regarding PLECS are answered on the Technical Solutions page of our website. Tutorial videos, specific application examples, and pre-recorded webinars are available on our YouTube page. Please follow us on LinkedIn for the latest Plexim news.

Simulation ERROR: Could not solve the algebraic loop

0 votes
I am trying to simulate a GSC based on simple 3 controlled voltage sources. Basically, I have implemented PQ-controller. When I try to simulate it produces an error;

At t=1.09623965334250585e-22: Could not solve the algebraic loop comprising the following components: 1: PI_PQCtrl_with_L_filter/Circuit1/3ph->SRF/alpha 2: PI_PQCtrl_with_L_filter/Circuit1/Sum2 3: PI_PQCtrl_with_L_filter/Circuit1/V8 4: PI_PQCtrl_with_L_filter/Circuit1/V7 5: PI_PQCtrl_with_L_filter/Circuit1/V6 6: PI_PQCtrl_with_L_filter/Circuit1/3ph Meter 7:

and so on...

I already tried to insert some delay element in the loop but it doesnt work. Could you please point out what are different solutions possible to this problem?

What should I need to change?

Attached the model
asked Nov 3, 2021 by adeel1 (27 points)

1 Answer

0 votes
The voltage input on the left hand side of your model is a linear function of a voltage measurement elsewhere in your circuit (i.e. linear relationship between "Vg_af" -> "Vg_nach" -> controlled voltage sources due to feedforward).  The voltage measurement at that node directly depends on the voltage input and the voltage input depends on the measurement.

As you suggested, one effective solution is to insert a delay in your control loop along that signal chain previously referenced.  One logical place would be just before your voltage source input on the left-hand side of your circuit that represents the modulator delay.
answered Nov 3, 2021 by Bryan Lieblick (1,301 points)