Browsing by Author "Haxhiu, Arber"
Now showing 1 - 7 of 7
- Results Per Page
- Sort Options
- Electric Power Integration Schemes of the Hybrid Fuel Cells and Batteries-Fed Marine Vessels - An Overview
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-06-01) Haxhiu, Arber; Abdelhakim, Ahmed; Kanerva, Sami; Bogen, JosteinTransportation electrification is undergoing a significant transition toward the utilization of efficient and reliable energy sources and smart integration schemes, where this transitioning is continuously facing ever-tightening challenges in order to comply with the increased environmental regulations. Among the different means of transportation, global maritime transport is responsible for 2%-3% of global greenhouse gas (GHG) emissions, and it is predicted to increase to 17% by 2050 if no changes are adapted. Hence, the international maritime organization (IMO) has targeted to reach a 50% reduction in GHG emissions by 2050 compared to 2008. Hence, alternative energy sources shall be utilized in order to meet these strict GHG emissions reduction targets, where battery- and hydrogen-fed fuel cells can play a vital role in such aspects. Since the output of these two energy sources is unregulated dc voltage, their connection to the whole ship power system can be accomplished in several ways, where each way has its features, in addition to utilizing different power conditioning stages (PCSs), and these features are not well clarified and compared in the literature. Hence, this article presents an overview of the possible integration schemes that can be utilized in fuel cell- and battery-fed vessels, which is supported with a comparative assessment. This is also presented along with highlighting the state-of-the-art PCSs that are available in the market and can be utilized in these integration schemes within marine vessels. Such overview and comparative assessment are seen to be of significant importance and added value for researchers and developers in both the academic and industrial sides in order to accelerate the adoption of fuel cells in marine systems for zero-emission shipping. - Improved Variable DC Approach to Minimize Drivetrain Losses in Fuel Cell Marine Power Systems
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-01) Haxhiu, Arber; Kyyrä, Jorma; Chan, Ricky; Kanerva, SamiThis article proposes a novel approach for operating hybrid fuel cell and battery power systems in marine vessels. The target of the approach is to reduce energy losses in drivetrain devices. In the proposed approach, the dc bus voltage of the hybrid power system is adjusted according to fuel cell operating points, which enables operation in freewheel mode, and thus significantly reducing power conversion losses. Feasibility of the proposed approach is verified using a real-time hardware-in-loop simulation setup consisting of prevalidated virtual models and real industrial power converter controllers. The results presented in the work illustrate that the variable dc approach enables significant improvements in drivetrain efficiencies, and thus providing significant savings for vessel operators. Additionally, variable dc approach is shown to eliminate high-frequency current ripple at the fuel cell terminals, which can further improve the efficiency and the lifetime of the fuel cells. - Modeling a DC Power System in Hardware-in-the-Loop Environment
Sähkötekniikan korkeakoulu | Master's thesis(2016-06-13) Haxhiu, ArberEver increasing requirements for increased fuel efficiency and reduced emissions on board a ship has prompted designers to turn their interest towards a distribution system where the main energy carrier is DC instead of AC. A DC power plant offers significantly reduced fuel consumption and easier integration of an increasing number of DC based sources and consumers, but also requires a more complicated control system for smart operation of the power plant. Therefore, the role of testing these control systems becomes even more important than before. This work introduces a Hardware-in-the-Loop (HIL) simulation technique for modeling and simulating a DC power plant on board a ship. In HIL simulation technique, a control-loop is built by using components, of which some are real hardware and some are simulated. This thesis work explores the possibilities for using the HIL simulation technique to perform real-time system level tests for a DC power plant on board a ship. The interfaces required to connect the real hardware components to the HIL simulator, and that way to the software component models as required by the simulation, will be examined. These interfaces consist of fieldbus communication (IEC61850 and Modbus) and a combination of digital and analog input and output signals. The goal of the HIL model of this work, is to offer an environment where different control schemes of the DC power system and the operation of the upper level power management and energy management systems can be tested safely and in a controlled manner. This requires that at least the controllers in the generating units are modeled using real hardware. The rest of the system can be modeled using virtual component models in the HIL software. A HIL model for modeling and simulating a complete DC power plant will be proposed and finally, the possibility to expand the model to include larger systems with more hardware will be discussed. - Modified Variable DC Approach Applicable to Fuel Cells and DOL Batteries in Shipboard Power Systems
A4 Artikkeli konferenssijulkaisussa(2020-09-27) Haxhiu, Arber; Kyyrä, Jorma; Chan, Ricky; Kanerva, SamiPreviously, a Variable DC approach has been proposed for hybrid fuel cell and battery shipboard systems. The approach was shown to reduce system powertrain losses, and hence cost of operation. However, in addition to cost, some vessel types are quite sensible to system weight and footprint. For such vessels, use of batteries without power converters is an attractive solution. However, the Variable DC approach is not applicable to batteries integrated without power converters. This paper proposes modifications on the previously presented Variable DC approach. The new approach enables reductions in system weight and footprint, while also achieving improvements in powertrain efficiency. The validation of the proposed method is carried out using a real-time hardware in loop test setup. - Suurnopeusinduktiokoneen urituksen optimointi rautahäviöiden minimoimiseksi
Sähkötekniikan korkeakoulu | Bachelor's thesis(2015-05-26) Haxhiu, Arber - A system level approach to estimate maximum load steps that can be applied on a fuel cell powered marine DC system
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-11) Haxhiu, Arber; Chan, Ricky; Kanerva, Sami; Kyyrä, JormaThis paper presents a system level approach to estimate the maximum load steps on a hydrogen fuel cell powered marine system. In the proposed approach, a model has been developed to predict the system distribution voltage drop due to sudden load changes applied on the system. The estimated voltage drop is used as a metric to determine if a system can sustain the applied load change. Such technique is beneficial for system engineers in the early stage of marine system design and dimensioning. Additionally, the model can be used by a power management system to coordinate starting and stopping of fuel cells for improved system performance. In this work, the proposed approach is validated using a real-time hardware-in-loop simulation platform and it is demonstrated that the proposed approach is accurate within 1.2%. - A variable DC approach to minimize drivetrain losses in fuel cell marine power systems
A4 Artikkeli konferenssijulkaisussa(2019-04-24) Haxhiu, Arber; Kyyrä, Jorma; Chan, Ricky; Kanerva, SamiThis paper presents a method of operating a zero-emission power system in marine vessels. The main goal of the proposed method is to reduce losses of drivetrain devices. The power sources considered in this work are proton exchange membrane fuel cell and lithium-ion battery while the main power consumers are induction motors driven propulsion system. Both sources and consumers are connected to a common DC bus through power conversion devices. In the proposed method, the DC bus voltage level is controlled according to the loading of the fuel cells. By controlling the DC bus voltage, it allows operation of fuel cell DC/DC converter in freewheeling mode which significantly reduces the converter losses. In addition, this approach is also expected to reduce the motor and battery drive losses. Feasibility of the proposed operation method and loss calculations are presented on a real-time hardware-in-loop simulator consisting of real control units and virtual power device models.