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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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Investigating the Protection of Ship Electric Grids Against Lightning Strikes  
Investigating the Protection of Ship Electric Grids Against Lightning Strikes  
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