Issues with Slack Generator and Singular Jacobian Matrix

[1207ywy]

Dear Mr. Cui,
I hope this email finds you well.
I am currently conducting power system simulation research using ANDES. After replacing GENROU_1 with REGCV1, I have encountered some issues and seek your guidance
Issue Description:

1. Slack Generator Not Defined/Enabled:
   Despite the original IEEE 39-bus system containing a slack generator, the simulation still reports "Slack generator not defined/enabled." I have verified that the Slack device exists in the IEEE39 table.
2. Singular Jacobian Matrix:
   During the simulation, the Jacobian matrix is reported as singular, preventing the simulation from proceeding. The specific diagonal elements are listed, but the root cause remains unclear.
   Error Details:
   I have attached a screenshot of the error message for your reference.
   Questions:

• What could be causing these issues?
• Why might an islanding situation occur?
• How can I verify the system's connectivity?
  Thank you for your assistance. I look forward to your insights.
  Wishing you a pleasant day and smooth work!
  Best regards.