Optimal Flow of MVDC Shipboard Power Systems Using Second-Order Cone Programming Relaxation

Medium voltage DC (MVDC) microgrid systems are promising solutions for naval power systems with variable propulsion motor speeds and pulsed power loads. Future shipboard power systems rely on combination of high-energy and high-power density storage devices that need to share the load among other energy resources in a ship to ensure security and resilience of energy supply. In this paper, optimal energy management of droop-based MVDC shipboard power systems with multiple hybrid energy storage units is first formulated using nonlinear programming. Resistive and capacitive droop controllers are considered for energy units in the shipboard power system. To guarantee a global optimum exists, secondorder cone programming (SOCP) relaxation is used to convert the nonlinear formulation to its linear approximate. Results confirm the effectiveness of the proposed formulation in real-time and hour-ahead optimal flows.