Nonlinear Model Predictive Control for Navy Microgrids with Stabilizing Terminal Ingredients

TL;DR

This paper tackles voltage regulation and power sharing in MVDC naval shipboard microgrids faced with pulsed loads and disturbances. It proposes a Lyapunov-based nonlinear model predictive controller (LNMPC) with stabilizing terminal ingredients and a complex droop-based power-sharing scheme among SGs, BESS, and SCs. Recursive feasibility and Lyapunov stability are ensured by deriving a terminal cost from the discrete Lyapunov equation and enforcing an invariant terminal set. Case studies show LNMPC outperforms a PI controller in both voltage regulation and fast load sharing and remains robust to noise and load variation, achieving a MAPE as low as 0.007% and restoring voltage to 6 kV within 0.05 s.

Abstract

This paper presents a novel control strategy for medium voltage DC (MVDC) naval shipboard microgrids (MGs), employing a nonlinear model predictive controller (NMPC) enhanced with stabilizing features and an intricate droop control architecture. This combination quickly regulates the output voltage and adeptly allocates supercapacitors for pulsed power loads (PPLs), while the battery energy storage system (BESS) and auxiliary generators handle the steady state loads. A key feature of this study is the formulation of terminal cost and constraints, providing recursive feasibility and closed-loop stability in the Lyapunov sense, that offers a more robust and effective approach to naval power and energy management. By comparing the proposed Lyapunov-based NMPC with conventional PI controller under fluctuating PPLs, the control robustness is validated.

Figures (3)

• Figure 1: Proposed control scheme for hybrid DC navy MGs
• Figure 2: CS-1: MVDC naval shipboard MGs via Lyapunov-based NMPC and PI controller
• Figure 3: CS-2: Lyapunov-based NMPC for MVDC naval shipboard MGs under load uncertainty