.ObjectStab.Network.Controllers.TCULDiscrete

Information

Discrete implementation of Tap-Changing Under Load (TCUL) control system
according to method D1-D4 in [1] using a state-machine implementation of the
control system and tap changer mechanism.

Ideally the variable 'tappos' should be initialized to give a voltage deviation
within the deadband at the start of the simulatation. Failure to do so may result in
convergence problems with the initial value solver.

---
[1] P.W. Sauer and M.A. Pai, "A comparison of discrete vs. continuous
dynamic models of tap-changing-under-load transformers", in Proceedings
of NSF/ECC Workshop on Bulk power System Voltage Phenomena - III :
Voltage Stability, Security and Control,  Davos, Switzerland, 1994.