A Reduced Order Model for the Stable LC-Filter Design on Shipboard DC Microgrids

In advanced ships, the power request is increasing as most of the loads, including propulsion, are electrically supplied. This aspect represents a challenge when focusing on the dynamics performance in balancing the power flows and when considering the large amount of energy to be managed. To this issue, the DC technology is an effective solution to prioritize the flexibility of shipboard power systems and for a better use of onboard energy. A DC shipboard microgrid is a complex system, incorporating several controlled converters. Between the main priorities, certainly the system stability has a prominent role. Indeed, unstable interactions among controlled converters and their filtering stages can arise during the ship operation, thus eventually compromising the ship mission. As the analytical stability assessment on this controlled system is not feasible, then equivalent models or order reductions help when investigating on stability performance. In this work, a cascade-connected shipboard DC system is studied, and an analytical expression of its stability boundaries is attained. The stability results are verified by means of circuital simulations to identify when the load filters are negligible, then achieving the chased order reduction.