BS EN IEC 61400-24:2019
$215.11
Wind energy generation systems – Lightning protection
| Published By | Publication Date | Number of Pages |
| BSI | 2019 | 200 |
This part of IEC 61400 applies to lightning protection of wind turbine generators and wind power systems. Refer to Annex M guidelines for small wind turbines.
This document defines the lightning environment for wind turbines and risk assessment for wind turbines in that environment. It defines requirements for protection of blades, other structural components and electrical and control systems against both direct and indirect effects of lightning. Test methods to validate compliance are included.
Guidance on the use of applicable lightning protection, industrial electrical and EMC standards including earthing is provided.
Guidance regarding personal safety is provided.
Guidelines for damage statistics and reporting are provided.
Normative references are made to generic standards for lightning protection, low-voltage systems and high-voltage systems for machinery and installations and electromagnetic compatibility (EMC).
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 2 | National foreword |
| 5 | Annex ZA(normative)Normative references to international publicationswith their corresponding European publications |
| 9 | CONTENTS |
| 18 | FOREWORD |
| 20 | 1 Scope 2 Normative references |
| 22 | 3 Terms and definitions |
| 28 | 4 Symbols and units |
| 31 | 5 Abbreviated terms |
| 32 | 6 Lightning environment for wind turbine 6.1 General 6.2 Lightning current parameters and lightning protection levels (LPL) Tables Table 1 – Maximum values of lightning parameters according to LPL(adapted from IEC 62305-1) |
| 33 | 7 Lightning exposure assessment 7.1 General Table 2 – Minimum values of lightning parameters and related rolling sphereradius corresponding to LPL (adapted from IEC 62305-1) |
| 35 | 7.2 Assessing the frequency of lightning affecting a single wind turbine or a group of wind turbines 7.2.1 Categorization of lightning events 7.2.2 Estimation of average number of lightning flashes to a single or a group of wind turbines |
| 37 | Figures Figure 1 – Collection area of the wind turbine |
| 38 | 7.2.3 Estimation of average annual number of lightning flashes near the wind turbine (NM) Figure 2 – Example of collection area for a complete wind farm (ADWF) with10 wind turbines (black points) considering overlapping |
| 39 | 7.2.4 Estimation of average annual number of lightning flashes to the service lines connecting the wind turbines (NL) 7.2.5 Estimation of average annual number of lightning flashes near the service lines connecting the wind turbine (NI) |
| 40 | 7.3 Assessing the risk of damage 7.3.1 Basic equation Figure 3 – Collection area of wind turbine of height Ha and another structureof height Hb connected by underground cable of length Lc Table 3 – Collection areas AL and Al of service line dependingon whether aerial or buried |
| 41 | 7.3.2 Assessment of risk components due to flashes to the wind turbine (S1) 7.3.3 Assessment of the risk component due to flashes near the wind turbine (S2) |
| 42 | 7.3.4 Assessment of risk components due to flashes to a service line connected to the wind turbine (S3) 7.3.5 Assessment of risk component due to flashes near a service line connected to the wind turbine (S4) |
| 43 | 8 Lightning protection of subcomponents 8.1 General 8.1.1 Lightning protection level (LPL) Table 4 – Parameters relevant to the assessment of risk componentsfor wind turbine (corresponds to IEC 62305-2) |
| 44 | 8.1.2 Lightning protection zones (LPZ) 8.2 Blades 8.2.1 General 8.2.2 Requirements |
| 45 | 8.2.3 Verification 8.2.4 Protection design considerations |
| 48 | 8.2.5 Test methods |
| 49 | 8.3 Nacelle and other structural components 8.3.1 General 8.3.2 Hub 8.3.3 Spinner |
| 50 | 8.3.4 Nacelle 8.3.5 Tower |
| 51 | 8.3.6 Verification methods 8.4 Mechanical drive train and yaw system 8.4.1 General 8.4.2 Bearings |
| 52 | 8.4.3 Hydraulic systems Table 5 – Verification of bearing and bearing protection design concepts |
| 53 | 8.4.4 Spark gaps and sliding contacts 8.4.5 Verification 8.5 Electrical low-voltage systems and electronic systems and installations 8.5.1 General |
| 56 | Figure 4 – Examples of possible SPM (surge protection measures) |
| 57 | 8.5.2 Equipotential bonding within the wind turbine Figure 5 – Interconnecting two LPZ 1 using SPDs Figure 6 – Interconnecting two LPZ 1 using shielded cables or shielded cable ducts |
| 58 | 8.5.3 LEMP protection and immunity levels |
| 59 | 8.5.4 Shielding and line routing |
| 60 | 8.5.5 SPD protection Figure 7 – Magnetic field inside an enclosure due to a long connectioncable from enclosure entrance to the SPD |
| 61 | Figure 8 – Additional protective measures |
| 64 | 8.5.6 Testing methods for system immunity tests 8.6 Electrical high-voltage (HV) power systems |
| 65 | Figure 9 – Examples of placement of HV arresters in two typical mainelectrical circuits of wind turbines |
| 66 | 9 Earthing of wind turbines 9.1 General 9.1.1 Purpose and scope 9.1.2 Basic requirements 9.1.3 Earth electrode arrangements |
| 67 | 9.1.4 Earthing system impedance 9.2 Equipotential bonding 9.2.1 General 9.2.2 Lightning equipotential bonding for metal installations |
| 68 | 9.3 Structural components 9.3.1 General 9.3.2 Metal tubular type tower 9.3.3 Metal reinforced concrete towers 9.3.4 Lattice tower |
| 69 | 9.3.5 Systems inside the tower 9.3.6 Concrete foundation 9.3.7 Rocky area foundation |
| 70 | 9.3.8 Metal mono-pile foundation 9.3.9 Offshore foundation 9.4 Electrode shape dimensions |
| 71 | 9.5 Execution and maintenance of the earthing system 10 Personal safety |
| 73 | 11 Documentation of lightning protection system 11.1 General 11.2 Documentation necessary during assessment for design evaluation 11.2.1 General 11.2.2 General documentation 11.2.3 Documentation for rotor blades |
| 74 | 11.2.4 Documentation of mechanical systems 11.2.5 Documentation of electrical and electronic systems 11.2.6 Documentation of earthing and bonding systems 11.2.7 Documentation of nacelle cover, hub and tower lightning protection systems |
| 75 | 11.3 Site-specific information 11.4 Documentation to be provided in the manuals for LPS inspections 11.5 Manuals 12 Inspection of lightning protection system 12.1 Scope of inspection 12.2 Order of inspections 12.2.1 General |
| 76 | 12.2.2 Inspection during production of the wind turbine 12.2.3 Inspection during installation of the wind turbine 12.2.4 Inspection during commissioning of the wind turbine and periodic inspection |
| 77 | 12.2.5 Inspection after dismantling or repair of main parts Table 6 – LPS General inspection intervals |
| 78 | 12.3 Maintenance |
| 79 | Annexes Annex A (informative)The lightning phenomenon in relation to wind turbines A.1 Lightning environment for wind turbines A.1.1 General A.1.2 The properties of lightning A.1.3 Lightning discharge formation and electrical parameters |
| 80 | A.1.4 Cloud-to-ground flashes |
| 81 | Figure A.1 – Processes involved in the formation of a downward initiatedcloud-to-ground flash |
| 82 | Figure A.2 – Typical profile of a negative cloud-to-ground flash Figure A.3 – Definitions of short stroke parameters (typically T2 < 2 ms) |
| 83 | Figure A.4 – Definitions of long stroke parameters (typically 2 ms < Tlong <1 s) |
| 84 | Table A.1 – Cloud-to-ground lightning current parameters |
| 85 | Figure A.5 – Possible components of downward flashes(typical in flat territory and to lower structures) |
| 86 | A.1.5 Upward initiated flashes Figure A.6 – Typical profile of a positive cloud-to-ground flash Figure A.7 – Processes involved in the formation of an upward initiatedcloud-to-ground flash during summer and winter conditions |
| 87 | Figure A.8 – Typical profile of a negative upward initiated flash |
| 88 | Figure A.9 – Possible components of upward flashes(typical to exposed and/or higher structures) Table A.2 – Upward initiated lightning current parameters |
| 89 | A.2 Lightning current parameters relevant to the point of strike Table A.3 – Summary of the lightning threat parameters to be considered inthe calculation of the test values for the different LPS componentsand for the different LPL |
| 90 | A.3 Leader current without return stroke A.4 Lightning electromagnetic impulse, LEMP, effects |
| 91 | Annex B (informative)Lightning exposure assessment B.1 General B.2 Methodology to estimate the average annual flashes or strokes to the wind turbines of a wind farm and upward lightning activity in wind turbines B.2.1 General B.2.2 Methodology to determine average annual flashes to turbines of a wind farm estimation by increase of the location factor to consider upward lightning from wind turbines |
| 92 | Table B.1 – Recommended values of individual location factors |
| 93 | Figure B.1 – Winter lightning world map based on LLS data and weather conditions |
| 94 | Figure B.2 – Detailed winter lightning maps based on LLS data and weather conditions Figure B.3 – Ratio h/d description |
| 95 | B.2.3 Upward lightning percentage in wind farms B.3 Explanation of terms B.3.1 Damage and loss Table B.2 – Range of upward lightning activity as a function ofwinter lightning activity for wind farm located in flat terrain |
| 97 | B.3.2 Composition of risk B.3.3 Assessment of risk components |
| 98 | B.3.4 Frequency of damage |
| 99 | B.3.5 Assessment of probability, PX, of damage |
| 100 | B.4 Assessing the probability of damage to the wind turbine B.4.1 Probability, PAT, that a lightning flash to a wind turbine will cause dangerous touch and step voltage Table B.3 – Values of probability, PA, that a lightning flash to a wind turbine will causeshock to human beings owing to dangerous touch and step voltages (corresponds to IEC 62305-2) Table B.4 – Values of reduction factor rt as a function of the type ofsurface of soil or floor (corresponds to IEC 62305-2) |
| 101 | B.4.2 Probability, PAD, that a lightning flash to the wind turbine will cause injury to an exposed person on the structure B.4.3 Probability, PB, that a lightning flash to the wind turbine will cause physical damage Table B.5 – Values of factor Po according to the position of a person in the exposed area (corresponds to IEC 62305-2) Table B.6 – Values of probability, PLPS, depending on the protection measuresto protect the exposed areas of the wind turbine against direst lightning flash and to reduce physical damage (corresponds to IEC 62305-2) |
| 102 | Table B.7 – Values of probability PS that a flash to a wind turbine will causedangerous sparking (corresponds to IEC 62305-2) Table B.8 – Values of reduction factor rp as a function of provisions takento reduce the consequences of fire (corresponds to IEC 62305-2) Table B.9 – Values of reduction factor rf as a function of risk of fire ofthe wind turbine (corresponds to IEC 62305-2) |
| 103 | B.4.4 Probability, PC, that a lightning flash to the wind turbine will cause failure of internal systems B.4.5 Probability, PM, that a lightning flash near the wind turbine will cause failure of internal systems B.4.6 Probability, PU, that a lightning flash to a service line will cause injury to human beings owing to touch voltage |
| 104 | B.4.7 Probability, PV, that a lightning flash to a service line will cause physical damage B.4.8 Probability, PW, that a lightning flash to a service line will cause failure of internal systems |
| 105 | B.4.9 Probability, PZ, that a lightning flash near an incoming service line will cause failure of internal systems Table B.10 – Values of probability PLI depending on the line type and the impulse withstand voltage UW of the equipment(corresponds to IEC 62305-2) |
| 106 | B.4.10 Probability PP that a person will be in a dangerous place B.4.11 Probability Pe that equipment will be exposed to damaging event B.5 Assessing the amount of loss LX in a wind turbine B.5.1 General B.5.2 Mean relative loss per dangerous event Table B.11 – Loss values for each zone (corresponds to IEC 62305-2) |
| 107 | Table B.12 – Typical mean values of LT, LD, LF and LO(corresponds to IEC 62305-2) |
| 108 | Annex C (informative)Protection methods for blades C.1 General C.1.1 Types of blades and types of protection methods for blades Figure C.1 – Types of wind turbine blades |
| 109 | C.1.2 Blade damage mechanism |
| 110 | C.2 Protection methods C.2.1 General |
| 111 | C.2.2 Lightning air-termination systems on the blade surface or embedded in the surface C.2.3 Adhesive metallic tapes and segmented diverter strips Figure C.2 – Lightning protection concepts for large modern wind turbine blades |
| 112 | C.2.4 Internal down conductor systems C.2.5 Conducting surface materials |
| 113 | C.3 CFRP structural components |
| 114 | C.4 Particular concerns with conducting components Figure C.3 – Voltages between lightning current path and sensor wiring dueto the mutual coupling and the impedance of the current path |
| 115 | C.5 Interception efficiency |
| 116 | C.6 Dimensioning of lightning protection systems Table C.1 – Material, configuration and minimum nominal cross-sectional area ofair-termination conductors, air-termination rods, earth lead-in rodsand down conductorsa (corresponds to IEC 62305-3) |
| 117 | Table C.2 – Physical characteristics of typical materials used inlightning protection systems (corresponds to IEC 62305-1) |
| 118 | C.7 Blade-to-hub connection C.8 WTG blade field exposure C.8.1 General Table C.3 – Temperature rise [K] for different conductors as a function of W/R(corresponds to IEC 62305-1) |
| 119 | C.8.2 Application C.8.3 Field exposure Table C.4 – Range of distribution of direct strikes from field campaigns collectingdata on attachment distribution vs. the distance from the tip ofwind turbine blades, 39 m to 45 m blades with and without CFRP |
| 120 | Annex D (normative)Test specifications D.1 General D.2 High-voltage strike attachment tests D.2.1 Verification of air termination system effectiveness D.2.2 Initial leader attachment test |
| 122 | Figure D.1 – Example of initial leader attachment test setup A |
| 123 | Figure D.2 – Possible orientations for the initial leader attachment test setup A |
| 124 | Figure D.3 – Definition of the blade length axis during strike attachment tests Figure D.4 – Example of the application of angles during the HV test |
| 125 | Figure D.5 – Example of leader connection point away from test specimen |
| 126 | Figure D.6 – Initial leader attachment test setup B |
| 128 | Figure D.7 – Typical switching impulse voltage rise to flashover(100 μs per division) |
| 130 | D.2.3 Subsequent stroke attachment test |
| 131 | Figure D.8 – Subsequent stroke attachment test arrangement |
| 132 | Figure D.9 – Lightning impulse voltage waveform Figure D.10 – Lightning impulse voltage chopped on the front |
| 134 | D.3 High-current physical damage tests D.3.1 General D.3.2 Arc entry test Figure D.11 – HV electrode positions for the subsequent stroke attachment test |
| 136 | Figure D.12 – High-current test arrangement for the arc entry test |
| 137 | Figure D.13 – Typical jet diverting test electrodes |
| 138 | Table D.1 – Test current parameters corresponding to LPL I Table D.2 – Test current parameters for winter lightning exposure testing(duration maximum 1 s) |
| 139 | D.3.3 Conducted current test |
| 141 | Figure D.14 – Example of an arrangement for conducted current tests |
| 142 | Table D.3 – Test current parameters corresponding to LPL I Table D.4 – Test current parameters corresponding to LPL I (for flexible paths) |
| 143 | Table D.5 – Test current parameters for winter lightning exposure testing(duration maximum 1 s) |
| 144 | Annex E (informative)Application of lightning environment and lightning protection zones (LPZ) E.1 Lightning environment for blades E.1.1 Application E.1.2 Examples of simplified lightning environment areas |
| 145 | Figure E.1 – Examples of generic blade lightning environment definition |
| 146 | E.1.3 Area transitions E.2 Definition of lightning protection zones for turbines (not blades) E.2.1 General Table E.1 – Blade area definition for the example in concept A Table E.2 – Blade area definition for the example in concept B |
| 147 | E.2.2 LPZ 0 Table E.3 – Definition of lightning protection zones according to IEC 62305-1 |
| 148 | E.2.3 Other zones Figure E.2 – Rolling sphere method applied on wind turbine |
| 149 | E.2.4 Zone boundaries Figure E.3 – Mesh with large mesh dimension for nacelle with GFRP cover Figure E.4 – Mesh with small mesh dimension for nacelle with GFRP cover |
| 150 | E.2.5 Zone protection requirements Figure E.5 – Two cabinets both defined as LPZ 2 connected via the shieldof a shielded cable |
| 151 | Figure E.6 – Example: division of wind turbine into different lightningprotection zones |
| 152 | Figure E.7 – Example of how to document a surge protection measures (SPM) system by division of the electrical system into protection zones with indication of where circuits cross LPZ boundaries and showing the long cables running between tower base and n |
| 153 | Annex F (informative)Selection and installation of a coordinated SPDprotection in wind turbines F.1 Location of SPDs F.2 Selection of SPDs F.3 Installation of SPDs |
| 154 | F.4 Environmental stresses of SPDs Figure F.1 – Point-to-point installation scheme Figure F.2 – Earthing connection installation scheme |
| 155 | F.5 SPD status indication and SPD monitoring in case of an SPD failure F.6 Selection of SPDs with regard to protection level (Up) and system level immunity F.7 Selection of SPDs with regard to overvoltages created within wind turbines F.8 Selection of SPDs with regard to discharge current (In) and impulse current (Iimp) |
| 156 | Table F.1 – Discharge and impulse current levels for TN systems givenin IEC 60364-5-53 Table F.2 – Example of increased discharge and impulse current levelsfor TN systems |
| 157 | Annex G (informative)Information on bonding and shieldingand installation technique G.1 Additional information on bonding Figure G.1 – Two control cabinets located on differentmetallic planes inside a nacelle |
| 158 | G.2 Additional information on shielding and installation technique Figure G.2 – Magnetic coupling mechanism |
| 160 | Figure G.3 – Measuring of transfer impedance |
| 161 | Annex H (informative)Testing methods for system level immunity tests |
| 162 | Figure H.1 – Example circuit of a SPD discharge current test under service conditions |
| 164 | Figure H.2 – Typical test set-up for injection of test current |
| 165 | Figure H.3 – Example circuit of an induction test for lightning currents |
| 166 | Annex I (informative)Earth termination system I.1 General I.1.1 Types of earthing systems I.1.2 Construction |
| 168 | I.2 Electrode shape dimensions I.2.1 Type of arrangement |
| 169 | Figure I.1 – Minimum length (l1) of each earth electrode according to the class of LPS |
| 170 | I.2.2 Frequency dependence on earthing impedance Figure I.2 – Frequency dependence on the impedance to earth |
| 171 | I.3 Earthing resistance expressions for different electrode configurations Table I.1 – Impulse efficiency of several ground rod arrangements relativeto a 12 m vertical ground rod (100 %) Table I.2 – Symbols used in Tables I.3 to I.6 |
| 172 | Table I.3 – Formulae for different earthing electrode configurations Table I.4 – Formulae for buried ring electrode combined with vertical rods |
| 173 | Table I.5 – Formulae for buried ring electrode combined with radial electrodes Table I.6 – Formulae for buried straight horizontal electrode combinedwith vertical rods |
| 174 | Annex J (informative)Example of defined measuring points Figure J.1 – Example of measuring points |
| 175 | Table J.1 – Measuring points and resistances to be recorded |
| 176 | Annex K (informative)Classification of lightning damage based on risk management K.1 General K.2 Lightning damage in blade K.2.1 Classification of blade damage due to lightning |
| 177 | K.2.2 Possible cause of blade damage due to lightning Table K.1 – Classification of blade damage due to lightning |
| 178 | K.2.3 Countermeasures against blade damage due to lightning Figure K.1 – Recommended countermeasures schemes according to the incident classification |
| 179 | Table K.2 – Matrix of blade damages due to lightning,taking account of risk management |
| 180 | K.3 Lightning damage to other components K.3.1 Classification of damage in other components due to lightning K.3.2 Countermeasures against lightning damage to other components K.4 Typical lightning damage questionnaire K.4.1 General K.4.2 Sample of questionnaire Table K.3 – Classification of damage to other components due to lightning |
| 183 | Figure K.2 – Blade outlines for marking locations of damage |
| 184 | Annex L (informative)Monitoring systems Table L.1 – Considerations relevant for wide area lightning detection systems |
| 185 | Table L.2 – Considerations relevant for local active lightning detection systems Table L.3 – Considerations relevant for local passive lightning detection systems |
| 186 | Annex M (informative)Guidelines for small wind turbines |
| 187 | Annex N (informative)Guidelines for verification of blade similarity N.1 General N.2 Similarity constraints |
| 188 | Table N.1 – Items to be checked and verified when evaluating similarity |
| 189 | Figure N.1 – Definitions of blade aerofoil nomenclature |
| 190 | Annex O (informative)Guidelines for validation of numerical analysis methods O.1 General O.2 Blade voltage and current distribution Figure O.1 – Example geometry for blade voltage and current distribution simulations |
| 191 | O.3 Indirect effects analysis Figure O.2 – Example geometry for nacelle indirect effects simulations |
| 192 | Annex P (informative)Testing of rotating components P.1 General P.2 Test specimen P.2.1 Test specimen representing a stationary / quasi stationary bearing P.2.2 Test specimen representing a rotating bearing P.3 Test setup P.3.1 Test set-up representing a stationary/quasi-stationary bearing Figure P.1 – Possible test setup for a pitch bearing |
| 193 | P.3.2 Test set-up representing a rotating bearing Figure P.2 – Possible injection of test current into a pitch bearing |
| 194 | P.4 Test procedure Figure P.3 – Possible test setup for a main bearing |
| 195 | P.5 Pass/fail criteria Figure P.4 – Example measurement of the series resistance of the test sample Table P.1 – Test sequence for high current testing of rotating components |
| 196 | Annex Q (informative)Earthing systems for wind farms |
| 197 | Bibliography |
