E. P. Nicolopoulou, V. T. Kontargyri, I. F. Gonos, G. J. Tsekouras, E. C. Pyrgioti, I. A. Stathopulos, J. M. Prousalidis
3rd and 4th MARINELIVE Interna3onal Workshops on “Prime Movers” and “Ship Automa3on and Control” November 21-‐23, 2012 Athens, Greece
Shipboard Electric Power Plants: Complicated Power Systems DC and AC subsystems Various operating voltage and frequency levels Electric propulsion Extended electrification of all shipboard installations: All Electric Ship (AES)
POWER QUALITY PROBLEMS Malfunction of critical loads Total loss of the vessel Human casualties Environmental pollution
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Electric Power Quality (PQ) problems in Ship Electric Energy Systems (DEFKALION)
Starting Date: 1st January 2012 Duration: 42 months (up to September 30th, 2015) Project Coordinator: Dr. John Prousalidis, Associate Professor External Evaluation Committee: Mr P. Leontis, Intership Maritime Professor C. Hodge, BMT Defense Dr A. Greig, UCL Dr O. Nayak, Nayak Corporation Dr R. Bucknall, UCL 3
Electric Power Quality (PQ) problems in Ship Electric Energy Systems (DEFKALION) Research Teams 1st Team Naval Technology 2nd Team Energy Saving 3rd Team Electromechanical Energy Conversion 4th Team High Voltages Partners: Inter-‐university and inter-‐departmental co-‐operation • National Technical University of Athens ü School of Naval Architecture and Marine Engineering (Project coordinator) ü School of Electrical and Computer Engineering • University of Patras ü Department of Electrical and Computer Engineering • Departments of Electrical Engineering of the Technological Educational Institutions of Lamia, Larissa and Kavala • Visiting Researcher from the Georgia Institute of Technology (USA) Prof. Athanassios Meliopoulos 4
Electric Power Quality (PQ) problems in Ship Electric Energy Systems (DEFKALION)
Research Activities ü Investigation of PQ problems due to shaft generator operation ü Investigation of PQ problems due to thruster operation ü Investigation of PQ problems due to pod operation ü Analysis of impact of earthing (grounding) on PQ phenomena ü Analysis of PQ phenomena due to lightning strikes ü PQ Measuring and Monitoring System
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Electric Power Quality (PQ) problems in Ship Electric Energy Systems (DEFKALION): Work DescripGon-‐ImplementaGon
GENERATION
WP2 SHAFT GENERATORS
WP7 ELECTRIC GRID
MONITORING AND RECORDING
LOADS
WP5
WP6
WP3
WP4
GROUNDING
LIGHTNING
THRUSTERS
PODS
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ProtecGon schemes against lightning (WP 6) Former conceptions: Almost entirely metal hull no problems
Current status:
Overvoltages: insulation damages Discontinuities in the hull structure (joints, combination of steel and plastic/fiberglass)
Overcurrents: thermal stresses and damages on hull, cables, pipes, equipment etc.
Electronic equipment
Induced currents to sensitive electronic equipment
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Lightning strikes (WP 6): Work Process Data Collection
Investigation of the relevant regulations and standards Study of the behaviour of the hull during a lightning strike (theoretical analysis and simulations) Tests in the premises of the High Voltage Laboratory of NTUA with a scaled ship model
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Lightning strikes (WP 6): TheoreGcal Analysis The mesh of a ship’s steel hull will be used, exploiting the experience in marine structure design of naval architects (special attention regarding points of discontinuities such as joints or changes of materials).
Calculations based on an e x i s t i n g m e t h o d o l o g y f o r continental grounding systems, which analyzes the voltage distribution along and across the mesh of the “grounding” means (VFD-‐methodology)
Simulations with software suitable for electromagnetic analysis. Necessary features: • Time-‐domain solver • Modeling of material properties • Ability to simulate transient excitations
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Scaled models: TheoreGcal Background Similarity Theory : Results gained from experiments on scaled models can be converted to the original model based on the principle of Physical Similarity.
Dimensional Analysis Formation of dimensionless the magnitudes products from that appear in the equations of the problem: scale) Pi (model)=Pi (full (Buckingham Pi Theorem)
Geometrical Similarity
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Similarity Theory-‐Scaled Experiments Fields of application Naval engineering: Hydrodynamics of propulsion Telecommunications: RCS calculation
Wave radiation, scattering, transmission High voltage engineering: Calculation of impulse impedance for various electrode geometries Scaled experiments: Transmission lines Lightning protection systems (LPS) of buildings Lightning protection zone of ships
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PreparaGon of the experiments Determination of the physical quantities that describe the problem 2) Application of the dimensional analysis 3) Scale factors 4) Selection of experimental parameters such as: the dimensions of the ship model and of the water tank the material properties of the ship model and of the water solution the excitation parameters (lightning current or voltage amplitude) 1)
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Experimental setup • Scaled ship model • Grounded metallic water tank • Water solution with variable salinity • Surge generator • Recording devices (oscilloscope, voltage probe, current probe)
Surge generator
Water tank
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Equipment NTUA High Voltage Laboratory (accredited according to ISO 17025:2005) 9-‐stage Impulse Voltage Generator: 1.2/50μs, up to 1.8MV Impulse Current Generator: 8/20 μs, up to 25 kA
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Experimental Procedure Injection on the surface of the model of lightning current produced by an impulse current generator (8/20 μs, up to 25 kA). Recording of the voltage and current waveforms on critical points of interest Basic information about the current distribution on the surface of the model and the resulting overvoltages II. The impulse voltage produced by an impulse voltage generator (1.2/50μs, 1800 kV, 18 kWs) will be imposed on a metallic setup that will simulate the initiation of the lightning channel. Recording of the lightning attachment positions Statistical analysis: conclusions regarding possible onboard regions in danger I.
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Experimental Procedure III. Investigation of the interaction induced from lightning currents or
power fault currents between the steel hull of the ship model and other onboard neighboring "electrodes" either made of steel (i.e. another adjacent metal part of the ship, electrically insulated from the part where the injected current flows) or made of copper/aluminum (cable/winding of the ship electrical installation). IV. Investigation of the effect of nearby and not direct strikes Recording of the induced signals on the ship structure
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Future goals Reproduction of the corresponding full-‐scale magnitudes from the
scale-‐model measurements Conclusions about the behaviour of the ship’s hull during a lightning strike Comparison between experimental results and simulations of the full-‐scale and the scaled down model carried out with the software, assessing thus the validity of the proposed scaling procedure Overview of the vulnerable regions and the developed overvoltages and overcurrents -‐ direct or induced -‐ during a direct or nearby lightning strike Proposals for introduction of new protection measures
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ACKNOWLEDGMENT THE
WORK PRESENTED IN THIS PAPER HAS BEEN DEVELOPED WITHIN THE
THALES-DEFKALION PROJECT. THIS RESEARCH HAS BEEN COFINANCED BY THE EUROPEAN UNION (EUROPEAN SOCIAL FUND – ESF) AND GREEK NATIONAL FUNDS THROUGH THE OPERATIONAL PROGRAM "EDUCATION AND LIFELONG LEARNING" OF THE NATIONAL STRATEGIC REFERENCE FRAMEWORK (NSRF) - RESEARCH FUNDING PROGRAM: THALES: REINFORCEMENT OF THE INTERDISCIPLINARY AND/OR INTER-INSTITUTIONAL RESEARCH AND INNOVATION.
FRAMEWORK OF THE
Thank you for your attention!
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