Dynamic Modeling and Stability Analysis of Onboard DC Power System for Hybrid Electric Ships

IEEE Trans. Transp. Electrific.

Pedersen

et al. 2021

The hybridization of power systems offers the low-emission and energy-efficient marine vessels. However, it increases the complexity of the power system. Design, analysis, control, and optimization of such a sophisticated system require reliable and efficient modeling tools to cover a wide range of applications. In this work, a typical DC hybrid power system model is developed using a bond graph modeling approach. Necessary component models of varying degrees of fidelity are developed and integrated to build a system model with reasonable accuracy. The developed system model, along with the rule-based energy management system, is used to simulate the entire system and to investigate the load-sharing strategies as well as the system stability in various operating scenarios. Moreover, the simulation results are validated with experimental results conducted on a full-scale laboratory setup of DC hybrid power system and with a ship load profile. The results show that the system model is capable of capturing the fundamental dynamics of the real system. The hybrid power system model is further used to analyze the bus voltage deviation from its nominal value. The computational efficiency presented by the system is fairly good as it can simulate faster than real-time. The developed system model can be used to build up a comprehensive simulation platform for different system analysis and control designs. Index Terms-Marine hybrid power systems, onboard DC power systems, modeling, stability, power and energy management I. INTRODUCTION T HE International Maritime Organization (IMO) has proposed stringent regulations to reduce emissions and improve energy-efficiency from the shipping industry. The energy-efficiency, low-, zero-emission, and innovative technologies are being investigated to comply with the regulations [1]. The energy storage device (ESD) based zero-emission vessel is still challenging for all types of marine vessels due to the low energy density of ESDs [2], [3]. The low energy density of ESD is compensated by the conventional Manuscript

Section: Convertersmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Dynamic Modeling, Simulation, and Testing of a Marine DC Hybrid Power System

Ghimire

IEEE Trans. Transp. Electrific.

Pedersen

et al. 2021

“…Therefore, total of eight operation modes are expected to be considered as a finite-set constraint. The switching state vector and the AFE rectifier voltage are expressed in (3), and the resulting voltage vector of the AFE with v dc is determined by the states of the switches as in (4).…”

Section: A Afe Rectifiers With Predictive Controlmentioning

confidence: 99%

Modeling and Predictive Control of Shipboard Hybrid DC Power Systems

Park

IEEE Trans. Transp. Electrific.

2021

Self Cite

Although onboard DC power systems bring values for the power and propulsion system of the future hybrid ships, the main barrier for the development of such systems for large scale vessels is the technical operational issues such as stability and power quality and how to satisfy the related standards and regulations. In the advanced ship power systems, the conventional diode rectifiers are being replaced with active front end (AFE) rectifiers providing the control flexibility but at higher cost. However, to make such devices more profitable, the ship control system can be reconfigured to unlock the potentials of AFEs for the general system stability. This paper is dealing with the stability issue of hybrid DC power systems proposing a predictive control approach to improve the voltage regulation and better use of converters. The proposed method replaces the conventional direct power control (DPC) of AFE rectifiers with a model predictive control (MPC) and integrates the DC-DC converters in the same control platform. In this method, optimal control commands for the rectifiers and the DC-DC converter are calculated by the predictive control to minimize the DC bus voltage fluctuations, especially under the fast load changes. The controller is then extended to regulate the load sharing between the different energy units. The effectiveness of the proposed method is evaluated in simulation with a typical ship load profile as well as a real ship profile which have several operating modes such as steep load increase & decrease, high speed, and maneuvering operation. The performance of the proposed control strategy is compared with conventional controllers, and the results show that the new method can provide significant advantages in terms of fast and stable control performance, as well as the steady-state voltage regulation and enhancing the power smoothing function of the battery. Laboratory experimental data are also used for validation. Index Terms-Model predictive control, batteries, onboard DC power system, hybrid electric ships.

“…While integrating new technologies, the modeling and simulation studies not only help in optimal operation but also during the design and maintenance phases [5]. The power system modeling is also required for its stability analysis [6], [7] along with performance evaluation for a system with nonlinear dynamics [8], [9]. Moreover, modeling of faults and abnormal conditions in the components and system levels is imperative for the design, testing, and training of such a complex system.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Modeling and Real-Time Simulation of a Ship Hybrid Power System Using a Mixed-Modeling Approach

Ghimire

Reddy

2020 IEEE Transportation Electrification Conference &Amp; Expo (ITEC)

et al. 2020

The electrification of a ship power-train is growing at a fast pace to improve efficiency and reduce emissions. The implementation of new technologies requires test and validation using various modeling approaches. However, many of the existing models of the ship hybrid power system are too complicated and demand high computational requirements, which make them inappropriate for the real-time applications. The realtime simulation model offers the benefits of testing different control algorithms along with hardware-in-the-loop testing. The bond graph-based dynamic modeling of a ship hybrid power system with a DC grid is presented as applicable to realtime simulation. The overall system model is established using different component models with varying fidelity, so-called mixedmodeling approach. In this approach, the components and control functions are modeled with different complexity such that it can capture the necessary system dynamics while minimizing the computational time. Results show that the modeled system is capable of simulating different operating strategies of the hybrid power system. Moreover, the mixed-modeling approach has enabled the system to simulate in nearly 2.5 times faster than the real-time.