Reliability and Sensitivity Analysis of Meshed DC Shipboard Power Systems Using Stochastic Simulation

In DC shipboard power systems (DC-SPS), the high penetration of power electronic devices combined with the ship’s harsh operating conditions make the system-level reliability a critical design concern. However, the enhanced network structure of a meshed DC grid imposes an intricate relation between component and system functionality, complicating the reliability assessment. 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 method is first validated for a small-sided DC grid through comparison with an analytical method. Later, the model is applied to estimate the reliability, availability, and repair characteristics of a ring-type DC-SPS for a wind turbine installation vessel. The results quantify the impact of redundancy on the system adequacy, show the spread in the subsystem repair times, and reveal the system availability during both the initialization and steady-state operation. Besides the assessment of the designed grid, the MC method is used to perform sensitivity and Pareto analysis, quantifying the impact of component failure rate changes on the SPS reliability, and identifying the contribution of individual components to the system failure characteristic. Combined, these results guide the focus for future SPS reliability enhancements. © 2020 IEEE.