Ashraf Tantawy1 , Xenofon Koutsoukos1, Gautam Biswas1
1Vanderbilt University, Nashville TN, 37235, USA
Abstract:
Differential protection is a popular method to
protect aircraft generators against winding faults.
Traditional relay-based systems have a limited
capability to distinguish between differential current
resulting from a winding fault, and the one
resulting from measurement noise or current saturation,
resulting in false alarms and unnecessary
equipment shutdown. Modern aircraft generators
are monitored and controlled by advanced
generator control units, and therefore, sophisticated
signal processing algorithms can be implemented
to enhance the differential protection performance.
We propose and compare four different
differential detector designs, based on the
available information about measured currents,
for detection of persistent, short circuit faults in
the protected windings. Also, current sensors
are subject to intermittent, open circuit, cable
faults, resulting in degradation in the differential
detection performance. We propose an optimal
differential protection architecture, based on
the Neyman-Pearson criterion, to detect winding
short circuit faults in the presence of intermittent
cable faults. In this architecture, the system
switches between two different detectors, depending
on the cable health state.