lightening protection of roof top photo voltaic system

1. ROOF-TOP PHOTOVOLTAIC(PV)
LIGHTNING PROTECTION
By
ABIN K RAJU
S7 EEE
ROLL NO:58
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2. INTRODUCTION
 Energy crisis
 Perfect solution : Solar energy
 Photovoltaics : Solar energy to electrical energy
 Electrical equipment requires protection
 Main protection against lightening
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3. LIGHTNING PHENOMENON
 Discharge of atmospheric charges from cloud to cloud
or cloud to earth
 Cloud is at higher potential(+) when compared to
ground(-)
 Charge flow is always from higher to lower potential
 Thus cloud gets discharged to the earth or ground
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4. LIGHTNING PROTECTION
PHENOMENON
 Charge flow is always through low resistance path
 In LPS ,we produce a low resistance path by external
means
 The resistance of low resistance path should be less
than the resistance of air
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5. TYPES OF LIGHTNING STROKES
 DIRECT STROKES
Lightening discharge is directly from the cloud to the
subject equipment . It produces high level transients.
 INDIRECT STROKES
It results from the electro statically induced charges on the
conductors due to the presence of charge clouds . It produces
low level transients.
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6. ISOLATED AND NON-ISOLATED
SYSTEM
 Isolated system :
lightning protection
system is isolated from
the system
 Non-isolated system:
potentially damaging
voltage differentials are
limited by bonding the
lightning protection
system to the structure
Isolated and non-isolated protection
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7. SEPARATION(ISOLATION) DISTANCE
REQUIREMENTS
 A separation distance
between the external LPS
and structural metal parts
is necessary
 This reduces the induction
of partial lightening
current internally
 There should have a
separation gap(s) between
lightning conductor and
structural parts Concept of separation distance
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8.  EARTHING SCREEN
To protect the power stations and substations from
direct strokes
 OVERHEAD GROUND WIRES
To protect the transmission lines against direct
strokes
 LIGHTENING ARRESTORS
To provide protection against travelling waves
which produces high voltage surge
METHODS OF LIGHTNING
PROTECTION
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9. LIGHTENING PROTECTION
SYSTEMS(LPS)
1. EXTERNAL LPS
 AIR TERMINATION SYSTEM
 DOWN CONDUCTOR SYSTEM
 EARTH TERMINATION SYSTEM
2. INTERNAL LPS
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10. EXTERNAL LPS
 Used to avoid direct strikes on the structures
 The principle is to catch the lightning strike on a
rod(lightning rod)
 And evacuate the energy to the ground with specific
down conductors
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11. 1. AIR TERMINATION SYSTEM
 A conducting device
mounted above the highest
point of a building
 It provides protection by
discharging atmospheric
electric charges to down
conductor
 They are of 3 types:
1.Air Rods(finials)
2.Catenary(suspended)
3.Meshed conductor
Air rod on the top of building
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12. Continues……..
 The tracing of optimum location of air termination
system is determined by 3 methods
1.The rolling sphere method(RSM)
2.The protection angle method(PAM)
3.The mesh method(MM)
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13. ROLLING SPHERE METHOD
 This is a simple method to
find area needs to be
protected
 Used to determine side
strikes
 In this a sphere is rolled over
the surface of structure
 The point where sphere
touches is vulnerable to
lightning and needs air
termination
 This determines which class
of protection is needed
Rolling sphere method
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14. CLASS OF PROTECTION
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15. THE PROTECTIVE ANGLE METHOD
 This method is a
mathematical
simplification of the
rolling sphere method
 The protection angle is
measured by the radius of
the rolling sphere
 The protection angle varies
with the height of the air
termination & thus the
class of LPS
 This method is limited to
the height equal or less
than the rolling sphere
radius PAM for a single air rod
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16. Continues………
Effect of height of the reference plane
on the protection angle
PAM applied to an inclined surface
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17. THE MESH METHOD
 This method is for the
protection of plane or flat
surfaces
 This method is used only if
the meshed conductors are;
1. Positioned on the edges of
the surface
2. The mesh size is in
accordance with the
standard table
3. No metallic structures
should protrude outside
the volume
4. From each points at least 2
separate path should exists
to ground
Protection via mesh method
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18. Continues……..
Standard mesh size for mesh method
Mesh method for compound structures
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19. COMBINED PROTECTION OF
RSM,PAM&MM METHOD
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20. 2. DOWN CONDUCTOR SYSTEM
 Electrically conductive
connection between the
air termination
system&earth
termination
 To conduct the
intercepted lightning
current in the earth
termination system
 Implemented by
separate conducting rods
Down conductor system
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21. 3. EARTH TERMINATION SYSTEM
 To disperse the surge
current in down
conductors
 Main characteristics are:
1. Low electrical
resistance between
electrode and earth
2. Good corrosion
resistance
Earth termination system29-Jan-17 21

22. INTERNAL LPS
 The event of direct strike is protected by external
lightning protection system
 Apart from direct strike ,indirect or near by strikes
which generates electromagnetic pulse which
produces inductive coupling
 Internal LPS is used for the protection against indirect
strikes
 Internal LPS works on the principle of lightning
protection zones(LPZ)
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23. LIGHTNING PROTECTION ZONE
 In this the structure to
be protected is divided
into different zones
 In this the lowest zone
has the highest effect of
lightning
electromagnetic pulses
Lightning protection zones
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24. ARRANGEMENT OF LPZ
Lightning protection zone concept29-Jan-17 24

25. ROOF TOP PV SYSTEMS
 Building Integrated Photo Voltaic(BIPV) as an
implementation of solar energy had high demand at
present
 Due to the mounting height and extended surface it
has a great vulnerability to lightning interception
 Therefore the mounting design of BIPV should given
great care
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26. DESIGN OF LIGHTNING
PROTECTION SYSTEMS
 In this PV panel is an
isolated system from LPS
 That is a minimum
separation is kept
between LPS and PV
panel
 The mounting of the PV
panel should be in side
the range of protection
angle
Protection of PV panels applying
protection angle method
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27. SPD CONNECTION OF ROOF TOP PV
SYSTEMS
 In this the connection of
surge protective device to the
roof top PV system is shown
 From PV panel the dc output
is fed to the inverter
 Then it is fed to the main
distribution board and the to
the power line
 All metallic portions are
equipotentially connected to
the bonding bar
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28. CONCLUSION
 BIPV system is becoming emerging trend in india
 The PV panels are usually placed on the roofs of tall
buildings so the chance of lightning strikes are large
 To protect the panels available protection techniques
for safe guarding the buildings against direct strikes
are to be evaluated to provide a safe location to install
the PV system
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29. REFERENCE
 http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnu
mber=6564584&isnumber=6564504
 https://en.m.wikipedia.org/wiki/lightning_rod#/searc
h
 https://en.m.wikipedia.org/wiki/photovoltaic_system
 http://schirtec.at/technical-information/lightning-
protection-theory/
 https://www.google.co.in/search?q=protection+by+lig
htening+rod+method&oq=protection+by+lightening+
rod+method&aqs=mobile-gws-lite
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