DEva Report

A
Seminar Report
on
Wind Turbine Lightning
Protection
Submitted By:
Borase Devendra Vijayrao
B.E. [Department of Mechanical Engineering]
Guided By:
Prof.V.M.Patil
Department of Mechanical Engineering
R. C. Patel Institute of Technology,
Shirpur-425405
2016-17

Shirpur Education Society’s
R. C. Patel Institute of Technology,
Shirpur, Dist-Dhule
CERTIFICATE
This is to certify that Borase devendra Vijayrao
from B.E[Mechanical Engineering] has satisfactorily car-
ried out seminar work on “Wind Turbine Lightning
Protection” and submitted the report in the premises of
Department of Mechanical Engineering under the guid-
ance of Prof.V.M.Patil during year 2016-2017.
Date:
Place: Shirpur
Seminar Guide Coordinator
Head of Department Principal

Acknowledgement
I take this opportunity to express my heartfelt gratitude towards the Depart-
ment of Mechanical Engineering, RCPIT, Shirpur that gave me an opportunity for
presentation of my seminar in their esteemed organization.
It is a privilege for me to have been associated with Prof.V.M.Patil, my guide
during seminar work. I have been greatly beneﬁted by her valuable suggestion and
ideas. It is with great pleasure that I express my deep sense of gratitude to her for
her valuable guidance, constant encouragement and patience throughout this work.
I express my gratitude to Prof.N.P.Salunke[Head Of Department] for his con-
stant encouragement, co-operation and support and also thankful to all people who
have contributed in their own way in making this seminar success.
I take this opportunity to thank all the classmates for their company during the
course work and for useful discussion I had with them.
Under these responsible and talented personalities I was eﬃciently able to com-
plete my seminar in time with success.
Borase Devendra Vijayrao

Abstract
The lightning protection standards describe how wind turbine blades should be
protected from the tip and down to radius 20m, whereas only a few evidences of
such exposure has been presented. Both numerical simulations as well as extensive
field data provide evidence that the direct strike exposure is focused on the tip of
the blade, and that the peak current of strokes expected inboard are of limited
amplitude. This has led to the Lightning Zoning Concept for blades, as well as a
revised approach of the Exposure Risk assessment which is treated in the present
paper. In 2015 a zoning concept for lightning protection of wind turbine blades was
published, refined slightly in 2015. The Zoning concept was developed to present an
engineering tool for assessing which lightning strikes that attaches to the different
regions of the blade. In the present paper, this Zoning concept is revised based on
more recent analysis and field investigations, and defines regions of the blade that
would be exposed to certain peak currents

Contents
List of Figures iii
1 Introduction 1
1.1 Types of wind turbine . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Horizontal Axis Wind Turbine . . . . . . . . . . . . . . . . . . 1
1.1.2 Vertical axis wind turbine . . . . . . . . . . . . . . . . . . . . 2
1.2 lightning and its eﬀect . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1 What is lightning . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.2 DIRECT EFFECTS (strikes on structures) . . . . . . . . . . 4
1.2.3 INDIRECT EFFECTS (network overvoltages) . . . . . . . . . 5
2 Literature Survey 6
3 Grounding, Bonding, Surge protection Lightning protection 8
3.1 Critical elements of blade lightning system Conductor Technology . . 8
3.1.1 Permanent, Low-Impedance Connections . . . . . . . . . . . . 9
3.1.2 Receptor Attachment . . . . . . . . . . . . . . . . . . . . . . . 10
4 Wind turbine protection 12
4.1 Composition of the Turbine Blade with Lightning Protection . . . . 12
4.2 Shielding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.3 VPC Protection (uptower control box) . . . . . . . . . . . . . . . . . 13
4.4 Base Controller Protection . . . . . . . . . . . . . . . . . . . . . . . . 14
4.5 Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.6 Existing Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.6.1 Standard for the Installation of Lightning Protection Systems,
NFPA 780 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.6.2 Protection of Structures Against Lightning, IEC 61024 . . . . 16
4.6.3 The Assessment of Risk Due to Lightning, IEC 61662 . . . . 16
4.6.4 Protection Against Lightning Electromagnetic Impulses, IEC
61312 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
4.6.5 Grounding of Industrial and Commercial Power Systems,
IEEE 142- 1991 . . . . . . . . . . . . . . . . . . . . . . . . . . 17
i

5 Advantages and disadvantages of wind mill 18
Conclusion 20
References 21
ii

List of Figures
1.1 Fig:Horizontal Axis and Vertical axis wind turbine . . . . . . . . . . 2
1.2 Fig:Nomenclature of the wind turbine . . . . . . . . . . . . . . . . . 4
1.3 Fig:Eﬀects of lightning . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1 Fig:Critical elements of blade lightning system Conductor Technology 9
3.2 Fig:Permanent, Low-Impedance Connections . . . . . . . . . . . . . 10
3.3 Fig:Receptor Attachment . . . . . . . . . . . . . . . . . . . . . . . . 11
iii

Chapter 1
Introduction
WIND TURBINE :- A wind turbine is a device that converts the wind’s
kinetic energy into electrical power.
1.1 Types of wind turbine
1.1.1 Horizontal Axis Wind Turbine
A horizontal Axis Wind Turbine is the most common wind turbine design. In
addition to being parallel to the ground, the axis of blade rotation is parallel to the
wind ﬂow.
A)up wind turbine Some wind turbines are designed to operate in an upwind mode
(with the blades upwind of the tower). Large wind turbines use a motor-driven
mechanism that turns the machine in response to a wind direction. Smaller wind
turbines use a tail vane to keep the blades facing into the wind.
B)down wind turbine Other wind turbines operate in a downwind mode so that the
wind passes the tower before striking the blades. Without a tail vane, the machine
rotor naturally tracks the wind in a downwind mode.
1

RCPIT, Shirpur Department of Mechanical Enggineering
Figure 1.1: Fig:Horizontal Axis and Vertical axis wind turbine
1.1.2 Vertical axis wind turbine
Although vertical axis wind turbines have existed for centuries, they are not as
common as their horizontal counterparts. The main reason for this is that they do
not take advantage of the higher wind speeds at higher elevations above the ground
as well as horizontal axis turbines.
Nomenclature of wind turbine
• Blade:- Most turbine have three blades. The turning of blades generate elec-
tricity.
• Hub :- Centre of the rotor to which the rotor blades are attached.
• Rotor:- Blade and hub referred together.
• Gears:- Connects low speed shaft to high speed shaft and increases rotational
speeds from 30 to 60 rpm to about 1000to 1800 rpm.
• Generator:- Device which produce electricity.
Wind Turbine Lightning Protection 2

• Controller:- Starts up and shuts of the machine.
• Anemometer:- Measure wind speed and Transmit wind speed data to con-
troller.
• Wind wane:- Measure wind direction and communicates with yaw drive to
orient the turbine.
• Yaw drive:- Keep rotor facing into the wind as wind direction changes.
• Nacelle:- Contain gear box, low and high speed shafts, generator, controller
and brakes.
• Tower:-Made from tubular steel, concrete or steel lattice. Taller tower generate
more power.
• Pitch:-Blades are turned, or pitched, to control rotor speed.
• Brake:- Stops rotor In emergencies.

Figure 1.2: Fig:Nomenclature of the wind turbine
1.2 lightning and its effect
1.2.1 What is lightning
Lightning is a sudden electrostatic discharge that occurs during an electrical storm.
This discharge occurs between electrically charged regions of a cloud (called intra-
cloud lightning or IC), between that a cloud and another cloud (CC lightning), or
between a cloud and the ground (CG lightning).
1.2.2 DIRECT EFFECTS (strikes on structures)
At the point of the strike, lightning generates: - Direct thermal effects (melting,
fire) caused by the electric arc - Thermal and electrodynamic effects induced by
circulation of the lightning current - Blast effects (shock wave and blast air) produced
by heat and the expansion of the air. Protection against the direct effects of lightning
is based on catching the current and discharging it to earth (lightning conductor,

Figure 1.3: Fig:Eﬀects of lightning
catcher rods, etc).
1.2.3 INDIRECT EFFECTS (network overvoltages)
Overvoltages due to lightning can reach the installation by three means of access: -
By conduction following direct lightning strikes on lines (power, telecommunications,
TV, etc.) entering or exiting buildings.

Chapter 2
Literature Survey
McElroy et al.[1], Mongolia, sandwiched between Russia and China, has
a high potential for wind-powered energy. As an emerging and developing country
with a large land size, Mongolia is an excellent choice for renewable energy practices,
according to McElroy at al. (2009). Currently, coal is used as the major source of
energy in the area because it is abundant and cheap. However, with the advancement
of wind turbine technology and its widespread use and production, wind powered
energy is becoming a cost eﬀective way to harness energy sustainably . A sustainable
energy resource is one that can be used renewably over our lifetimes and brings little
to no impact on our worlds ecosystems.
Khushrushahi et al [2], Currently, according to Noushin Khushrushahi
et at. (2006), Mongolia receives the majority of energy from coal-powered plants.
Coal is a readily available fuel because nearly half of Mongolia is a coal basin. This
makes coal very easy to obtain and very cheap for energy generation. Because
Mongolia uses so little energy (compared to developed nations), most people see
little sense in changing to a more expensive and harder to install renewable energy.
Up to eighty percent of Mongolias energy is from coal and the remaining comes
mostly from hydroelectric generators. To date, Mongolia uses just under 800 MW
of energy but is steadily increasing their need for energy. In theory, the cheapest
and easiest way for Mongolia to obtain more power would be to import their energy
from China.
6

Zervos et.al [3], the Asian market added nearly one third of the total
new wind generators installed worldwide in 2008. In total, 36.5 billion (50 billion)
was spent on turbine instillations worldwide that year. Almost half a million people
are employed in some way by the wind energy industry and that number is growing
steadily. With the current use of wind energy, over 158 million tons of carbon
dioxide are saved from entering the atmosphere annually. Today, the United States
leads with the world in wind energy generation, producing over 25,000 MW . Wind
energy is now being produced world-wide and developing nations have began turning
to wind powered renewable energy.

Chapter 3
Grounding, Bonding, Surge
protection Lightning protection
3.1 Critical elements of blade lightning system
Conductor Technology
Lightning protection conductors are designed and manufactured to meet specific
criteria for an effective and reliable conduction of lightning currents. For optimal
performance, the conductors must maintain the following characteristics:
• Low inductance per unit length
• Low surge impedance Current-carrying capability to withstand, without degra-
dation, the thermal and mechanical effects of lightning
• Resistance to environmental effects When applied to applications with wind
turbine blades, the construction and design of the blade may require additional
characteristics for the conductors. Insulation, splicing and termination meth-
ods adequate to contain the lightning energy under current impulse conditions
8

Figure 3.1: Fig:Critical elements of blade lightning system Conductor Technology
• Ability to withstand mechanical fatigue over time The application of optimal
conductors within wind turbine blades is both unique and often complicated,
and varies from one blade design and construction to another. ERICOs ex-
tensive knowledge and experience within this industry make it ideally suited
to face these challenges. By manufacturing a wide selection of lightning con-
ductor solutions in multiple facilities around the world, ERICO can provide
the high-quality, innovative products and services you require to consistently
meet your needs.
3.1.1 Permanent, Low-Impedance Connections
It is Who We Are Connections are often considered the weakest point of an electrical
circuit and this is especially true in the protection scheme within a wind turbine
blade. They are subject to constant vibration and corrosion, as well as the thermal
and mechanical stresses that are present during a lightning event. In addition, it is
diﬃcult to inspect or test the electrical connections within a blade after the system
has been installed. Experience has shown that the most eﬀective protection schemes
over time are designed and manufactured with permanent connections, which helps
to ensure the system can handle a variety of adverse conditions.

Figure 3.2: Fig:Permanent, Low-Impedance Connections
Since 1938, ERICO has specialized in making electrical connections that will
never loosen, corrode or increase in resistance. Because of the affordability, success
and superiority of the CADWELD welded electrical connection, ERICO is consid-
ered a world leader in the development of high-current electrical grounding connec-
tions that are suitable for the harshest environments. ERICO also manufactures
a vast array of methods that are used to connect conductors within wind turbine
blades. These methods are designed and tested to meet the CENELEC EN50561
standard and other national standards, such as UL 96. Whether the protection
scheme requires an insulated connection, connections to receptors, or connections
from conductor to conductor, you can trust ERICO to have the right connection
method for your specifi c application.
3.1.2 Receptor Attachment
To continuously enhance its lightning protection process, ERICO has conducted
years of research involving long-term fi eld studies and has performed laboratory
testing using some of the largest outdoor test laboratories available. Countless
research study programs, including joint ventures with accomplished scientists in the
fi eld, have also been used in its research process. This extensive research program
has resulted in some of the most up-to date, published technical papers and journals,

Figure 3.3: Fig:Receptor Attachment
including patents in this area. ERICO is also committed to the development and
harmonization of lightning protection standards around the world. The placement
of receptors on structures, such as wind turbine blades, is performed using statistical
models. A risk management approach is required to determine the receptor number
and placement to provide optimum protection. The design of the receptor itself
also inﬂ uences its ability to capture the lightning. ERICO can provide receptors
based on the material type, design and size of the blade. Years of experience and
knowledge in the ﬁ eld of lightning protection, combined with global manufacturing
capabilities, make ERICO a premier source for providing comprehensive protection
solutions. ERICO can also manufacture the required products and hardware to
update existing systems.

Chapter 4
Wind turbine protection
4.1 Composition of the Turbine Blade with Light-
ning Protection
1.1 Construction of these 1.5MW turbine generator blades are fibreglas epoxy resin
with an exterior gel coat. The blade interior structure is spar-reinforced with rigid
polyurethane foam encased in fiberglass. Further interior strength is via sandwich
sheets of urethane/fibreglas/urethane/fibreglas in built-up layers. It is not within
the scope of this study to examine the cellular nature, sheer strength or other phys-
ical characteristics of urethane foam. However, crude experiments at the wind farm
showed water was absorbed into urethane samples.
1.2 Lightning protection consists of several exterior copper receptor air termination
discs, which are fastened to interior aluminum conductors running the length of
the blade. Conductors are fastened to the blade and to one another with steel
bolts. Near the blade root a portion of the conductor is imbedded into the fibreglas.
The conductor transitions from the blade root area via bonding to the hub and
thence to a ground reference. Other components of the lightning protection systems
were examined briefly. The manufacturer provided satisfactory surge protection for
sensitive electronics. Grounding requirements were completed per manufacturers
specifications by the installation contractor.
12

4.2 Shielding
• The nacelle cover is glass reinforced polyester (GRP) with no metal content.
No shielding is associated with this.
• The steel tower should be the ﬁrst level of shielding. As soon as wires enter
the tower, no further shielding is needed because the lightning current will be
conducted by the metallic tower to the earth. As such, the shields and ground
wires should be terminated on entry to the tower (i.e., at droop wire clamp
below gearbox).
• The steel variable pitch controller (VPC) box is the ﬁrst level of shield for
any sensors that conduct to it or any controller cards or devices inside it. LTI
recommends terminating shields at both ends (i.e., at the sensor and the VPC
box).
• Control and sensor wire shields and braids should be terminated at both the
VPC and the base controller.
• At any exposed areas in nacelle, sensors should also have an overbraid covering
the wires. (In places where the termination of sensor shield wire causes any
signal problems, remove the shield at the sensor but ensure that overbraid is
complete from sensor to VPC.)
4.3 VPC Protection (uptower control box)
• All sensors go down to the motherboard via the VPC terminal strip.
• Sensor shields are not grounded at the VPC. They are made common to other
shields and continued to base. This is bad practice because the combined
shields may cause coupling between sensors.
• Not all shields are terminated at base. Those that are terminate only at the
ground strip (bottom center of control box). They should be terminated as

soon as they enter box.
• The VPC box is not bonded to turbine frame or anywhere else. It is mounted
on rubber vibration mounts that stand the box off from the gearbox by about
19 mm (0.75 in.) (see Figure 11). The ground path is assumed to be in
sensor or control wires and shields to sensor housings or base controller. It
is recommended that the VPC be bonded to the local frame in at least two
places.
• No surge protection is offered to any sensors, the operator interface terminal
(OIT), or the modem that negotiates communication with the motherboard
in the downtower control box. It was unclear if there is surge protection on
the PC boards.
4.4 Base Controller Protection
• Ground bus on the 480 VAC side of box is on insulated standoffs, and at
no point is it connected to the control box. It is recommended that this be
bonded directly to the control box, making the whole control box the single
point ground (SPG).
• The sensor terminal strip should have direct-mounted lugs for grounding shields
to box. Currently they must travel to the terminal strip, through wireways to
the un-bonded ground bus, and finally into the rebar. Bonding these shields
directly at the entry to the box keeps unwanted current arriving in the shield
from being conducted inside the box along other control wires in the wire-way
• An isolation board is between most sensors and the controller card rack. This
appears to be optoisolation and signal conditioning for temperature probes
and other sensors.
• Custom 120 kA surge suppressors are installed at the three phase terminals
(to SPG) in the controller and at the terminals in the generator junction box.

4.5 Grounding
The grounding details are described for a typical turbine in Figure 13 and Figure
14. The grounding electrode was significantly modified with a retrofit designed by
Rich Kithill at the National Lightning Safety Institute (NLSI). Some observations
of the details follow:
• Each of the four tower legs are tied to a ground wire inside the concrete pier
(Ufer ground).
• Each tower leg is connected by copper braid to a ring electrode [30.5 m (100
ft) of 2/0].
• Two of the tower legs are connected by 2/0 copper braid to 46 m (150 ft) of
38 mm (1.5 in.) copper strap buried in irrigated bentonite laid out in 0.9 x 15
m (3 x 50 ft) radial crow’s feet (irrigated twice a month).
• All 3 phases of the 25 kV buried site feeder has a common braid terminated
at each turbine transformer box (primary side).
• The air terminal (lightning rod) on the nacelle has insulated 4/0 Cu welding
cable conducting to the ground braid (no bond to tower).
• The generator J-Box (generator ground) is connected by insulated 4/0 Cu
conductor to a tower bond 1.5 m (5 ft) from base (below sensor) and control
box.
• The controller path to ground is either via the neutral cable or via the feeder
transformer box into a ground rod and the ring electrode.
• The controller and uptower generator surge protection device clamps to SP
ground.

4.6 Existing Standards
4.6.1 Standard for the Installation of Lightning Protection
Systems, NFPA 780
NFPA 780 9 is from the standards group that maintains the National Electric Code,
and it is geared to installation details. However, this has little bearing in the pro-
tection of wind turbines because it is focused specifically on buildings and similar
structures. In fact, in the scope electric generating, transmission, and distribution
systems are specifically excluded.
4.6.2 Protection of Structures Against Lightning, IEC 61024
IEC 61024 10 is the primary standard for lightning protection of structures in Eu-
rope. The International Electrotechnical Commission maintains this and other light-
ning specific standards under TC81. It is an extremely useful document for design
and maintenance of lightning protection systems. This is especially true with siz-
ing down-conductors and ground electrodes. There is also good rationale for using
structural metal as natural conductors. Specific to wind turbines, the standard (as
of 1999) has not addressed tall structures those above 60 meters (196.8 feet) are
excluded. Also, in the scope electric generating, transmission, and distribution sys-
tems external to a structure are excluded. Nonetheless, the standard is a strong
design tool for general lightning protection.
4.6.3 The Assessment of Risk Due to Lightning, IEC 61662
IEC 61662 11 is used to assess the risk of lightning damage in terms of personnel
safety or cost. Procedures are provided to perform these analyses.

4.6.4 Protection Against Lightning Electromagnetic Im-
pulses, IEC 61312
IEC 61312 12 is a five part standard focused on protecting against damage to com-
munication and other low voltage systems. The use of lightning protection zones,
as a first line of defense, is well defined in Part 1. In fact, it is suggested that light-
ning protection systems can be made quite robust and efficient if Surge protection
devices are discussed thoroughly in Part 3 and somewhat in Part 1. Part 1 also has
a useful appendix on the waveforms that are expected at an installation and the
fundamental differences with waveforms used to test devices.
4.6.5 Grounding of Industrial and Commercial Power Sys-
tems, IEEE 142- 1991
IEEE 142 23 is somewhat outdated, but it describes good practices for any power
system especially those contained completely by a building. It is concerned with
primarily 60 Hz fault safety.

Chapter 5
Advantages and disadvantages of
wind mill
• Renewable energy
• Pollution free
• Cost eﬀective
• Does not use water
• No fuel charges
Disadvantages
• Causes death to wildlife, such as birds and bats
• Wind turbine cannot build anywhere
• Generate noise, some people does not like
• Wind is not always predictable
18

Conclusion
Wind turbine blade is one of the most vulnerable parts of the damage of light-
ning. On the basis of a large number of research data, this report analyzes the
mechanism of the damage caused by lightning strike, sums up several lightning
protection measures of the blades of the wind turbine and introduces one inven-
tion patent. At the same time, the author introduces a simulated experiment
about the blade struck by lightning in Japan. It shows that the installation of
lightning arrester can eﬀectively intercept lightning in the blade tip. Also, if the
lightning arrester is roughly the shape of a disk which installed on the surface
of the blade, it will engender electric arc inside.
19

References
[1] I.Cotton, B. McNiﬀ, T. Soerenson, W. Zischank, P. Christiansen,
M.Hoppe-Kippler, S. Ramakers, P. Pettersson and E. Muljadi: ”Light-
ning Protection for Wind Turbines”, Proceedings of the 25th International
Conference on Lightning Protection (ICLP), (Rhodes,Greece), pp.848-853,
2000 .Wada et al.: ”Lightning Damages of Wind Turbine Blades in Win-
ter in Japan -Lightning Observation on the Nikaho-Kogen Wind Farm-”,
Proceedings of the 27th International Conference on Lightning Protec-
tion(ICLP), (Avignon,France), pp.947-952, 2004
[2] EC TR 61400-24, Wind turbine generator systems-Part 24:Lightning pro-
tection, 2002
[3] .Yokoyama, N.J.Vasa: ”Manner of Lightning Attachment to Non-
conductive Wind Turbine Blades”, Proceedings of the 27th International
Conference on Lightning Protection (ICLP), (Avignon,France), pp.936-
940, 2004
[4] akehiro Naka, Nilesh J. Vasa, Shigeru Yokoyama, Atsushi Wada, Akira
Asakawa, Hideki Honda, Kazuhisa Tsutsumi and Shinji Arinaga: ”Study
on Lightning Protection Methods for Wind Turbine Blades”, IEEJ Trans-
actions on Power and Energy, Vol.125, No.10, pp.993-999, 2005
20

References
[1] I.Cotton, B. McNiﬀ, T. Soerenson, W. Zischank, P. Christiansen,
M.Hoppe-Kippler, S. Ramakers, P. Pettersson and E. Muljadi: ”Light-
ning Protection for Wind Turbines”, Proceedings of the 25th International
Conference on Lightning Protection (ICLP), (Rhodes,Greece), pp.848-853,
2000 .Wada et al.: ”Lightning Damages of Wind Turbine Blades in Win-
ter in Japan -Lightning Observation on the Nikaho-Kogen Wind Farm-”,
Proceedings of the 27th International Conference on Lightning Protec-
tion(ICLP), (Avignon,France), pp.947-952, 2004
[2] EC TR 61400-24, Wind turbine generator systems-Part 24:Lightning pro-
tection, 2002
[3] .Yokoyama, N.J.Vasa: ”Manner of Lightning Attachment to Non-
conductive Wind Turbine Blades”, Proceedings of the 27th International
Conference on Lightning Protection (ICLP), (Avignon,France), pp.936-
940, 2004
[4] akehiro Naka, Nilesh J. Vasa, Shigeru Yokoyama, Atsushi Wada, Akira
Asakawa, Hideki Honda, Kazuhisa Tsutsumi and Shinji Arinaga: ”Study
on Lightning Protection Methods for Wind Turbine Blades”, IEEJ Trans-
actions on Power and Energy, Vol.125, No.10, pp.993-999, 2005
21

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