Faculty of Civil and Industrial Engineering Dottorato di Ricerca in Ingegneria dei Materiali e delle Nanotecnologie (EMNE) XXXI CICLO Distortion and faults detection in shipboard AC/DC power distribution system Tutor: Candidate: Prof. Regina Lamedica Ing. Alessandro Ruvio Reviewers: Prof. Massimo Ceraolo Prof. Giorgio Sulligoi Summary Acronyms ........................................................................................................................................... 5 Introduction ........................................................................................................................................ 7 Chapter I: Overview of Electrical Maritime Systems ...................................................................... 10 1.1 Electrical Propulsion System in Ships ................................................................................... 10 1.2 Electric Propulsion – Historical overview.............................................................................. 12 1.3 Naval Classification ............................................................................................................... 14 1.3.1 Field of use ...................................................................................................................... 14 1.3.2 On-Board Power .............................................................................................................. 16 1.4 Electrical Generation On Board ............................................................................................. 16 1.5 Energy distribution ................................................................................................................. 19 1.5.1 Network layout ................................................................................................................ 19 1.5.2 Voltage levels .................................................................................................................. 20 1.5.3 Neutral operation ............................................................................................................. 21 1.6 Electric propulsion system ..................................................................................................... 22 1.7 Electric propulsion’s driver .................................................................................................... 24 1.8 Regulatory requirements and naval registers relating to environmental conditions .............. 29 1.9 Overall reflection about “All electric ship” ............................................................................ 30 1.10 Electrical system protection devices .................................................................................... 31 1.10.1 Selectivity techniques .................................................................................................... 36 Chapter II: Integrated Power System in Military Ships ................................................................... 38 2.1 Frigate Type 23 ...................................................................................................................... 38 2.2 Type 2400 Submarines (Victoria Class) ................................................................................ 39 2.3 Type 45 destroyer ................................................................................................................... 40 2.4 FREMM ................................................................................................................................. 41 2.5 Queen Elizabeth Class aircraft carrier .................................................................................... 42 Chapter III: Methodologies for Harmonic Disturbances Analysis and Power Quality (Service Continuity) ....................................................................................................................................... 45 3.1 Power Quality – Harmonic discussion ................................................................................... 45 3.2 Software and models .............................................................................................................. 46 3.2.1 Generators, cable and loads ............................................................................................. 46 3.2.2 Fortran Software: model for harmonic analysis .............................................................. 48 3.2.3 Simulink model for time varying non-linear load ........................................................... 50 3.3 Electrical System Dependability [2] ...................................................................................... 53 Chapter IV: Characterization of A Military Aircraft Carrier ........................................................... 56 4.1 System description ................................................................................................................. 56 4.2 On-board electrical loads characterization ............................................................................. 58 4.2.1 SWBS groups .................................................................................................................. 58 4.2.2 Operating role .................................................................................................................. 59 4.2.3 On-board loads - Macro categories definition ................................................................. 60 2 Chapter V: Cavour Aircraft Carrier– Measurement campaign [97] ................................................. 61 5.1 Measurement campaign organization ..................................................................................... 61 5.2 Measurement campaign results .............................................................................................. 62 5.2.1 Time domain ................................................................................................................... 63 5.2.2 Frequency domain ........................................................................................................... 70 5.3 Software and model validation ............................................................................................... 75 5.3.1 Load Flow ....................................................................................................................... 75 5.3.2 Network impedance analysis – Z(f) ................................................................................ 75 5.3.3 Total Harmonic Distortion evaluation ............................................................................. 77 5.3.4 Simulink model for time varying non-linear load ........................................................... 79 Chapter VI: A New layout for an Integrated Power System Naval Unit-All Electric/Hybrid ......... 80 6.1 Aims of the chapter [99]......................................................................................................... 80 6.2 MV All electric ship ............................................................................................................... 81 6.3 All electric MVAC - alternating current MV system ............................................................. 86 6.3.1 Normal operation (full propulsion power) ...................................................................... 87 6.3.2 Emerging operation (half propulsion power) .................................................................. 88 6.4 All electric MVAC "hybrid" - MV system with alternating current with "islands" / electrical areas in direct current, in MV and/or Low Voltage (BT). ............................................................ 89 6.4.1 Normal operation (full propulsion power) ...................................................................... 90 6.4.2 Emerging operation (half propulsion power) .................................................................. 91 6.4.3 DC island ......................................................................................................................... 91 6.5 Definition and characterization of a "hybrid" propulsion naval unit...................................... 93 6.5.1 Network architecture ....................................................................................................... 97 6.5.2 50 Hz network - load conditions ..................................................................................... 98 6.5.3 60 Hz network -load conditions .................................................................................... 102 Chapter VII: Network Equivalents in Frequency Domain ............................................................. 105 7.1. Electrical network case study .............................................................................................. 105 7.3 Network impedance.............................................................................................................. 111 7.3.1 Network impedance evaluation for each equivalent network model ............................ 111 7.3.2 – The Network Equivalent Accuracy ............................................................................ 114 7.3.2.1 Comparison among network equivalents ................................................................... 114 7.3.2.2 - Influence of cables length on network impedance calculation ................................ 117 Chapter VIII: Harmonic Analysis .................................................................................................. 118 8.1 Network impedance.............................................................................................................