Active Fault Protection for an AC Zonal Marine Power System Architecture

This paper proposes a new protection scheme for marine power systems (MPS). The scheme exploits the increased use of power electronic devices to provide a useful complement to traditional protection strategies which can also provide the necessary back up protection during extreme protection failure, without the need for communication channels. The scheme is described for an AC zonal Advanced Power System architecture employing power electronic Bus Interface Units, An Active Fault Protection scheme is presented based on active impedance estimation from these Bus Interface Units. The power system impedance is measured by injecting a very short current transient onto the network via a coupling inductance and analyzing the transient response to this using the measured voltages and currents. Wavelet analysis is used in the data processing to estimate the system impedance over a broad frequency range; the identified impedance can be used for fault discrimination. The speed, accuracy and range of validity of such an approach are fully explored.