Medium Voltage Direct Current (MVDC) Grounding System

Hepburn and Sons LLC teamed with Florida State University (FSU) Center for Advanced Power Systems (CAPS) has successfully analyzed seven different grounding methods against forty-nine comparison criteria and successfully delivering the Phase I Final Report. The seven grounding methods evaluated during Phase I include: 1) Ungrounded/Floating; 2) High Resistance Grounding (HRG); 3) Low Resistance Grounding (LRG); 4) Impedance Grounding; 5) Solid Grounding; 6) Diode Grounding; and 7) Active Grounding. We have concluded that a HRG method provides the most technically feasible and appropriate solution to grounding MVDC power distribution within ships. The team proposes to further test out the HRG methodology during Phase II. The HRG method will be thoroughly tested at the FSU CAPS facility simulating a ship’s power system. This testing will be performed to verify that a HRG system will operate adequately with comparable hardware. Testing will also provide design limits for the system that will be used in the design specifications of future ships. The team will also investigate interference between multiple zones to ensure there is not excessive interference when implementing a HRG system with representative equipment. We will also continue evaluating US Patent 8067942 B2, Method for locating phase to ground faults in DC.