The application of wavelets to shipboard power system protection

The proposed integrated power systems (IPS) of navy ships is based on an ungrounded system. However the natural capacitance of the cable and the EMI filters provide ground paths to the ship\´s hull. There is thus a "virtual ground" between the modules of the IPS. The fault current is very low for a single line to ground fault in this ungrounded system allowing continuous operation but also making fault detection difficult. In this paper a method of ground fault detection using wavelets is introduced. The ground fault conditions are simulated using PSPlCE and fault detection implemented with Daubechies wavelets. It is shown that ground faults can be detected by wavelet analysis of the line to line voltages.