Hierarchical Control of Under-Load Tap-Changing Transformers Using DES

Hierarchical structlire is a common featuie of control solutions of complex dynamic systems. In large discrete-event system (DES) supervisory c ontr ol, hierarchical struchtre pr ovides the solution with simplified abstract models in the h i ghe r I ev e l. tJ nde rJ o ad t ap- changing tr ansfo r e r s ( Lfq which obviously have discrete-event behaviour are widely used in transmission systems to take care of instantaneous variations in the load conditions in substations ULTC may be controlled either automatically or manually. In this paper, a hierarchical supemisory control for an under-load tap-changing transformer is discussed in Automatic mode ofoperation. The consistency ofthe high level model is investigated. It is shown that a high level manager can shut down the tap-changing mechanism after abnormal behaviour in the plant such as a specific number of tap up/down failures.

Keywords:

Hierarchical Supervisory Control , Discrete-Event System , Automatic Voltage Control of Tap-ChangerT ransformers