Assessment failure in Task 1 of Solar Energy module: P_AC signal shows incorrect at the end of simulation.

I am experiencing a persistent assessment failure in the "Solar Energy" section, Task 1, of the Power Systems Simulation Onramp course.

The Problem: I have connected the signal labeled P_AC to the Signal Assessment block as instructed. The connection in the model is a solid black line, yet the assessment returns "Incorrect" with a hint suggesting an unconnected signal.

Symptoms:

• The Assessment graph shows red dots (incorrect data) specifically at the end of the simulation period (approx. seconds 23-25).
• I have confirmed that the Enable MPPT block is set to 0.

Steps already taken:

1. Deleted and re-connected the P_AC signal multiple times to ensure a solid connection.
2. Ran the simulation until completion (100% ready).
3. Used the "Reset" button for the task and re-attempted.

Could you please check if this is a known issue with the auto-grader for this specific task?

Answer 1

[Cris LaPierre]

It looks like there is a very small numeric difference which is causing the assessment to fail. This model was updated to use Simulink Electrical blocks instead of Specialized Power Systems, which introduced the difference.

The workaround until this is fixed is to use the original model with the SPS blocks. I'm attaching a file with this model. Replace the entire model in task 1 (except for the assessment block) with this one. With both models open, delete the model in the onramp, then copy and paste this model in its place.

[Cris LaPierre]

There are 4 changes

In Ideal DC to AC

• Fourier Analysis is changed back to Fourier block (SPS, to be removed in R2026a)

In Ideal DC to AC > Single Phase DC to AC

• Fourier Analysis is changed back to Fourier block (SPS, to be removed in R2026a)
• Power Consumption is changed back to Power block (SPS, to be removed in R2026a)
• Gain block is added to the Fourier angle output signal to convert it from degrees to radians (Gain = pi/180)

[Kunkamol]

Thank you so much! My issue is now resolved after using the file you provided.