ATP representation of cycloconverter drives for rolling mills: a useful tool for protection design purposes

A cycloconverter drive for a rolling mill is considered and a detailed modelling of the system obtained by means of ATP (Alternative Transient Program) is presented, as regards power and control circuits as well as the protection devices and logic. The techniques for achieving a proper model are then illustrated and a case study is presented to show the use of the model for evaluating the fault effects on a real system. A modular approach based on the use of an ATP graphical interface is adopted for system representation, which also makes the tool suitable for nonprofessional ATP programmers.