Guest Editorial Energy Conversion in Next-Generation ... - IEEE Xplore

IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 32, NO. 2, JUNE 2017

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Guest Editorial Energy Conversion in Next-Generation Electric Ships UTURE electric ships, vessels, and ferries will predominately use the integrated power system architecture and energy distribution network, combining conventional loads (e.g., propulsion) and, in case of navy ships, pulsed loads (e.g., radars, rail guns, and aircraft launchers). These loads represent increasing energy demands, and require improved transient characteristics and capacity of power systems compared to the traditional and legacy ships. The common approach to meet the increasing energy demands is to integrate more generation sources and storage units into the ship power system. Development of real-time modeling and simulation environments, highperformance control paradigms, and advanced energy management systems is required to ensure stable and optimal operation of resulting complex energy distribution and conversion systems of modern and future electric ships. This special section brings together papers focused on the recent advancements in energy conversion techniques used in electric ship technologies. We have followed a two-tier review process. First, we have invited authors to submit extended abstracts for a preliminary review based on the scope of the special issue and abstract quality. Then, out of 60 submitted extended abstracts, the authors of 34 abstracts were invited for full paper submission. The submitted manuscripts underwent a full formal review process, after which only 10 papers were accepted for publication in this special section. The accepted papers are broadly classified into three themes: i) simulation, estimation, and control; ii) power and energy management; and iii) stability related issues. A brief discussion of each paper and the authors’ contributions are presented below.

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I. SIMULATION, ESTIMATION, AND CONTROL The paper “System-Level, FPGA-Based, Real-Time Simulation of Ship Power Systems” by Milton et al. exploits the inherent parallelism and low-latency in FPGAs to offer a scalable simulation environment for power systems populated with highfrequency power electronics converters. The numerical solver employed is the parallelizable latency-based linear multi-step compound method. A very small 50 ns simulation time-step has been achieved for various simulated cases, including a threephase DC/AC converter, a single-bus ship power system, and a dual-bus shipboard power system. The paper “Medium Voltage DC Power Systems on Ships: An Off-Line Parameter Estimation for Tuning the Controllers’ Linearizing Function” by Bosich et al. performs off-line tests to estimate parameters needed to tune the linearizing functions that can be used in the state feedback process. The method overcomes the requirements to have the complete knowledge of system parameters. The estimation process uses selective search methods, and Digital Object Identifier 10.1109/TEC.2017.2698798

is compared with the conventional particle swamp optimization (PSO) techniques. Dynamic simulations validate the proposed estimation techniques, and show better voltage transients as compared to when only the designed parameters were used. The paper “Enhancing Fault-Tolerant Ability of a Nine-Phase Induction Motor Drive System Using Fuzzy Logic Current Controllers” by Liu et al. combines fuzzy logic control with a flux-oriented control to improve the fault-tolerant capability of a nine-phase induction motor drive. Experimental validations show satisfactory dynamic response for the proposed fuzzylogic controller over the traditional proportional-integral (PI) controllers for various faulty or transitory scenarios. The paper “Real-Time Distributed Coordination of Power Electronic Converters in a DC Shipboard Distribution System” by Hossain et al. describes a multi-agent control and optimization paradigm. The proposed optimization framework minimizes the power distribution requirements and optimally allocates energy sources, while respecting the operational boundaries and capacities. In part based on mixed-integer programming, this optimization algorithm is implemented in a distributed fashion, where proper handling of search trees has reduced the communication overhead. This algorithm is verified on a simulated shipboard power system. II. POWER AND ENERGY MANAGEMENT The paper “Fuel Cell Power Management Using Genetic Expression Programming in All-Electric Ships” by Tashakori et al. uses genetic algorithms for power management in hybrid fuel cell-battery systems. The flow rates are related to the dclink voltage, and used to achieve stable operation of the hybrid energy system without using interfacing DC/DC converters. The paper “Predictive Control for Energy Management in Ship Power Systems Under High-Power Ramp Rate Loads” by Tuyen et al. offers a hybrid model predictive control scheme to coordinate the generation and storage under unbalanced conditions. The optimization process leads to generation references in the presence of pulsed loads and propulsion motors with high-power ramp rate demands. The proposed scheme is experimentally validated on a ship power system. The paper “Fuzzy Logic Based Energy Storage Management System for MVDC Power System of all Electric Ship” by Khan et al. proposes a fuzzy logic-based energy management of hybrid battery-supercapacitor storage systems to maintain the DC bus voltage within a reasonable range, while meeting the sudden load demands common in all-electric ships. The resulting energy management system manages charging/discharging of battery/supercapacitor using the DC bus voltage, current, charge status of storage units, and the load demand, without the typical protection for extra-deep charging or overcharging. Power sharing techniques are proposed to accommodate multiple hybrid storage units. Performance comparison with PI control-based

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IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 32, NO. 2, JUNE 2017

energy management systems is provided. Studies are conducted in Matlab/SimPowerSystems for various state-of-charges scenarios. Some studies are replicated in a controller hardware-inthe-loop environment. The paper “Load Sharing in Ship Microgrids Under Nonsinusoidal Conditions—Case Study” by Tarasiuk et al. investigates the sharing phenomena in ship’s distribution network populated with power electronics devices and distorted waveforms. The sharing of power quantities defined in IEEE 1459-2010 (e.g., active and reactive powers) between parallel generators is assessed for various loading conditions. Examples of studies include power flow and power harmonics. This paper also revisits some provisions of ship classification. III. STABILITY RELATED ISSUES The paper “Meta-Stability of Pulse Power Loads Using the Hamiltonian Surface Shaping Method” by Weaver et al. presents a large-signal stability analysis, based on Hamiltonian Surface Shaping and Power Flow Control, as an alternative to existing small-signal analysis used in conjunction with pulsed power loads. Therein, the notion of stability is re-defined as metastability that includes bounded instability followed by a damping period, and the proposed method identifies the stability boundaries. The results are validated by numerical simulation, hardware-in-the-loop, and physical experiments. The paper “Medium-Voltage Impedance Measurement Unit for Assessing the System Stability of Electric Ships” by Jakˇsi´c et al. designs and implements a medium-voltage impedance measurement unit, based on power electronics building blocks, to measure the small-signal dq impedances of both AC and DC systems using a single-phase wide-bandwidth injection. The method uses cross-correlation techniques for in-situ characterization of interfacing impedances for hybrid power systems. The proposed impedance identification approach is validated experimentally on medium-voltage grids. ACKNOWLEDGMENT We would like to sincerely thank the coordination teams at the IEEE Power and Energy Society and the IEEE TRANSACTIONS ON ENERGY CONVERSION, contributing authors, and anonymous reviewers for making this special section a reality. We are particularly very grateful to Dr. J. Jatskevich, the Editor-in-Chief of the IEEE TRANSACTIONS ON ENERGY CONVERSION, as well as R. Scholnick-Philippidis and K. Capaldo at the Executive Office of the IEEE Power and Energy Society, for their technical insight and timely support. J. GUERRERO, Guest Editor-in-Chief Aalborg University Aalborg 9100, Denmark A. DAVOUDI, Guest Editor-in-Chief University of Texas-Arlington Arlington, TX 76019 USA

K.A. CORZINE, Guest Associate Editor Clemson University Clemson, SC 29634 USA A. M. CRAMER, Guest Associate Editor University of Kentucky Lexington, KY 40506 USA R. DOUGAL, Guest Associate Editor University of South Carolina Columbia, SC 29208 USA S. GAMINI, Guest Associate Editor University of Tasmania Hobart, TAS 7005, Australia Y. KHERSONSKY, Guest Associate Editor Consultant, USA S. KOURO, Guest Associate Editor Universidad Tecnica Federico Santa Maria Valpara´ıso 1680, Chile M. MOLINAS, Guest Associate Editor Norwegian University of Science and Technology Trondheim 7491, Norway A. MONTI, Guest Associate Editor RWTH Aachen University Aachen 52062, Germany Y. TANG, Guest Associate Editor Nanyang technological University Singapore, 639798 D. OPILA, Guest Associate Editor United States Naval Academy Annapolis, MD 21402 USA E. HENNIE, Guest Associate Editor Sintef Trondheim 4761, Norway A. J. SORENSEN, Guest Associate Editor Norwegian University of Science and Technology Trondheim 7491, Norway G. SULLIGOI, Guest Associate Editor University of Trieste Trieste 34127, Italy S. D. SUDHOFF, Guest Associate Editor Purdue University West Lafayette, IN 47907 USA

M. BELKHAYAT, Guest Associate Editor Huntington Ingalls Industry Newport News, VA 23607 USA

K. SUN, Guest Associate Editor Tsinghua University Beijing 100084, China

M. EL HACHEMI BENBOUZID, Guest Associate Editor University of Brest Brest 29238, France

T. TARASIUK, Guest Associate Editor Gdynia Maritime University Gdynia 81-225, Poland