Slew Run Messages
"Round Rotor Gen Slew Run Diverged (IMag)."
"Round Rotor Gen Slew Run Exceeded Max Iters."
"Ind2 Motor Slew Run Diverged (IMag)."
"Ind2 Motor Slew Run Diverged (Slip)."
"Ind2 Motor Slew Run Exceeded Max Iters for PF Conditions."
"Ind2 Motor Slew Run Exceeded Max Iters at Full Load."
Description - These are initialization errors. The machine model noted incorporates saturation and other non-linear methods, and thus initialization of the model cannot be performed directly. An iterative error driven minimization technique is used (slew run). If the generator terminal conditions are extreme, this iterative technique may diverge. Several message types are seen when these conditions occur, and these are:
- Diverged (IMag) - This notes that the terminal current magnitude triggered the divergence sensor.
- Exceeded Max Iters - This notes that the slew run did not converge by the time it reached the maximum number of enabled iterations.
- Diverged (Slip) – This notes that induction motor slip triggered the divergence sensor.
Fix - Review the machine’s terminal conditions (P and Q) and determine if the equipment is indeed being asked to perform far beyond its rated capability. Modify the machine in the power flow case to bring it within an acceptable loading. Alternatively, the model data may be corrupt, and may not be representing a reasonable machine characteristic. If you are using your own data, try replacing it with EasyPower-provided model data from the model library. Compare constants to see where your data may be in error.
Odd Root Cause – In the process of running simulations with induction motors, we have found an instance where this message is generated, but the causes above are not at the root of the issue. In one instance we discovered that the base frequency had been set to a high value of 400 Hz, due to a system being created after running a 400 Hz simulation of an airport runway grid. The high base frequency caused a motor with data specified for 50 or 60 Hz to diverge during the slew run.
