In DC shipboard power systems (DC-SPS), the enhanced network complexity and high penetration of power electronic devices make the system level reliability a critical design aspect. This paper proposes a stochastic framework for the reliability assessment of DC-SPSs based on a three-stage Monte Carlo (MC) simulation, including component failure sampling, active fault propagation, and reliability index calculation. The proposed MC framework is verified for a simplified meshed DC grid through comparison with an analytical method. Later, the advantages of the MC method are demonstrated for a dynamic positioning vessel equipped with a ring-type DC power system architecture. The results quantify the impact of redundancy on the reliability of a DC-SPS, show the spread in the subsystem repair times, and reveal the system's availability during both the initialization and steady-state. Combined, the simulation results reveal the strengths and weaknesses of the designed grid, guiding the focus for future reliability enhancements.

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When operating a modular multilevel converter (MMC), a margin appears between the arm voltage and sum capacitor voltage corresponding to the power dependent ripple. This margin can be used to enhance the DC link voltage and increase the transfer capacity of an MMC-based distribution link while keeping the submodule (SM) stresses fixed. Consequently, this dynamic enhancement in transfer capacity can be achieved with the same submodule switch and capacitor voltage ratings. Using an arm-level averaged simulation model of a 10MW MMC-based MVDC link, the enhancement concept is verified and shown to be beneficial to a practical link application. Besides, a dependency is discovered between the enhancement limit and the grid-injected reactive power, which defines the basis of the proposed control for dynamic enhanced operation.@en

Reliable Power Electronic Systems (PES) are vital for enabling energy transition technologies of the future. Power hardware-in-the-Loop (PHIL) test bed can be used to validate such systems cost-effectively and time-efficiently. In general, the Real Time Digital Twin (RTDT) is a virtual representation of the PES and its operating environment that mimics its behavior in real-time to provide adequate flexibility to the test bed. The workflow of alternating between the prototype and twin, for instance, overcomes the dilemma of needing 100 % details (due to fast dynamics), but optimization during design choices requires cheap flexibility. In this paper, some use cases in applications of RTDT-based PHIL test bed such as fault tolerant converters, power electronic interface for green technologies, survivable all-electric ships, mission profile-based reliability testing, protection of multi terminal dc systems and reconfigurable hybrid ac-dc links is discussed. Furthermore, the co-simulation potential of real-time platforms is briefly described.@en