Risk Mitigation through Protection - Solar Dynamix Mitigation through Protection Agenda Damages to...

© 2015 DEHN + SÖHNE / protected by ISO 16016

Risk Mitigation

through Protection

1


Risk Mitigation through Protection

Agenda

Damages to PV Systems

Standards and Norms

Lightning Protection Concepts

Questions & Answers

Video: Isolated Lightning Protection System

2


Reason for Lightning Damage

about 20-24 million lightning strikes per year in SA

A comprehensive approach to Lightning Protection 3

* source: BLIDS, Siemens AG, evaluation from 2000 - 2010

electrical conductive systems



Direct/Nearby lightning strikes to building


20 kV

IT systemPower supply

Rst

380 kV

110 kV

110 kV

230 V

20 kV

1

1b

1a

1 Direct lightning strike:

Induced voltages in loops

Voltage drop at the conventional earthing impedance Rst

1a

1b



Direct/Nearby lightning strikes to power supply system


20 kV

IT systemPower supply

380 kV

110 kV

110 kV

230 V

20 kV

2c

2a

Rst

2 Remote lightning strike:

2c Fields of the lightning channel

2aLightning strike in a medium-voltage overhead line

2b Travelling surge waves in overhead line due to cloud to-cloud lightning


LPLCurrent

amplitude (kA)

I 200

II 150

III - IV 100


Galvanic coupling – Lighting impulse voltage


Rst = 1 Ω

MEB

ûE = î · Rst

Example: ûE = 100 kA · 1 = 100 kV

ûE = impulse voltage

î = impulse current

RSt= conventional earthing resistance

1 Ω

100 kV

100 kA

MEB: main earthing busbar Ref.: IEC 62305-1



PV Modules Damage

Combiner Box Damage

Inverter Damage

Communication System Damage

Sensitive Equipment Damage (Trackers, Security Systems)

Damage Statistics

7



PV Modules Damage

source: Solarzentrum Oberland GmbH

Arcing/Short-circuiting of PV Modules due to lightning

8



PV Modules Damage

Broken glasses, Burned/Melted DC Cables and Combiner Box

Defective bypass diodes

9



Combiner Box Damage

source: R. Schüngel, Munich

Melted Combiner Boxes and DC Cables

due to Short-Circuit currents

Breakdown of sensitive and or monitoring

components inside Combiner Box

10



Inverter Damage

Internal component failure inside an Inverter (Central & String)

11



Communication System Damage

Holes in the Cable insulation

Data cables causing failure of Switches, PLC’s etc…

12



Damage Statistics – Comparison (Frequency of Occurence)

Causes of damage (2003-2013)

Evaluation Mannheimer Versicherung

Causes of damage (2005-2014)

Evaluation Bayerischer Versicherungsverband

source: Bayerischer Versicherungsverband 2014source: Mannheimer Versicherung 2014

South Africa has on average 10 times more lightning density (strikes/km2)

13



Damage Statistics – Damages Costs

source: Bayerischer Versicherungsverband 2014

Costs of Damages (2005-2014)

Evaluation Bayerischer Versicherungsverband

14


Standards & Norms

SANS 10313: 2012

SANS (IEC) 62305: 2010-12

EN 62305: 2009-10 (VDE 0185-305: 2012)

15


Standards and Norms

SANS 10313:2012 & SANS (IEC) 62305:2010-12

16


Standards and Norms

EN 62305: 2009-10 (VDE 0185-305: 2012)

17

© 2015 DEHN + SÖHNE / protected by ISO 16016 A comprehensive approach to Lightning ProtectionA comprehensive approach to Lightning Protection 18

IEC 62305:2010-2012, Part 2

Risk Assessment

In order to evaluate whether or not lightning protection is needed, a RISK

ASSESMENT in accordance with the procedures in IEC 62305 Part 2 shall be

made. Protection against lightning is needed if the Calculated Risk is higher than

the Tolerable Risk (RX > RT)


Type of Loss RT(y)

Loss of Human Life 10e-5

Loss of Service to the Public 10e-3

Loss of Cultural Heritage 10e-3

Loss of Economic Value

Note:

10e-5 = 1 in 100 000 chance of a

fatal injury over the course of 1

year (Maximum tolerable risk)


Standards and Norms

Reasons why a LPS is required by Owners/Insurers

19

DETAIL DESCRIPTION

Investment (Capital) > R Millions/Billions

Life time of the plant and equipment > 20 years

Return on Investment (Business Model) Linked to kWh output

Downtime due to damaged components > Time (hrs/days)

Insurance Access payable with every claim > R 500 k

Insurance premium hikes due to claims TBD

Breakdown of equipment due to inherent effects > R xxx

Degradation of equipment and components > R xxx

Lightning and surge protection measures are essential!


IEC 62305:2010-2012, Part 2

Reduction of the risk below the value of the tolerable risk RT

A comprehensive approach to Lightning ProtectionA comprehensive approach to Lightning Protection 20A comprehensive approach to Lightning Protection 20

RA RV

RB

risk

measures to

reduce the risk

tolerable risk RT


IEC 62305:2010-2012, Part 2



RA RV

RB

risk

measures to

reduce the risk

tolerable risk RT


IEC 62305:2010-2012, Part 2



RA RV

RZ

risk

measures to

reduce the risk

tolerable risk RT


IEC 62305:2010-2012, Part 2

Risk of damage (RX)


NX

Frequency of

lightning

strikes

PX

Probability of

damage

(Structure)

LX

Possible

Loss

RX = NX ∙ PX ∙ LX


Frequency of lightning strikes (NX)

Lightning ground flash density (NG)



Standards and Norms

Frequency of the risk of a Lightning Strike in South Africa

26

ITEM DETAIL

Output (MWp) 75

Modules > 600k

Area (km2) 3

Lightning Density (strikes/km2) 5.8

Total Direct Lightning (year) 17.4

Rain Season (months) 5 – 6

Total Strikes in Rain Season (p/month) 3 – 3.5

Total Cost of the Plant R 2 Bil

Total Loss as a result of Lightning (year)

without Protection

R 20

Mil

Lightning and surge protection measures are essential!


IEC 62305:2010-2012, Part 2

Risk Analyses

The selection of the most suitable protection measures shall be made by the

authority having jurisdiction to the type and the amount of each kind of damage.

Once the Risk is defined the appropriate LPL is determined.

Also it is important to note that a LPS mitigates risk but does not eliminate it.



External Lightning Protection

Air-termination Systems (ATS)

Isolated LPS: Separation Distance

Down-conductor Systems (DCS)

Earth-termination System (ETS)

Photovoltaic – Causes


Standards and Norms

DIN EN 62305-3 suppl. 1 (VDE 0185-305-3 suppl. 1):2012-10

(translation)

The required class of LPS (I-IV) is determined by means of a risk analysis

according to DIN EN 62305-2 (VDE 0185-305-2). The class of LPS can

also be defined in consultation with the planner, owner and/or user.

Regulatory requirements frequently call for lightning protection

measures for this type of structure to prevent fire and/or to protect

persons.

If possible, a lightning protection system should be preferred which is

not directly connected to the photovoltaic power supply system and

where adequate separation distances are kept.

29


IEC 62305:2010-2012, Part 1

General Principles

Lightning protection

Lightning protection means protection measures against the harmful

effects of lightning strikes to structures/buildings.

An external lightning protection system consists of:

Air-termination system

Down conductor

Earth-termination system

Earth-termination system

An earth-termination system includes all measures required for

connecting an electrical part to earth and is an integral part in low-

voltage and high-voltage systems as well as for the lightning protection

system.

26.09.13 / 8494_E_1


Standards and Norms

IEC 62305:2010-2012, Part 1

A lightning protection system consists of an external and internallightning protection system.

Functions of an external lightning protection system:

Interception of direct lightning strikes by means of an air-terminationsystem

Conducting the lightning current to earth by means of a downconductor

Distribution of the lightning current in the earth by means of anearth-termination system

Functions of an internal lightning protection system:

Prevention of dangerous sparking in the structure by establishingequipotential bonding or keeping a separation distance between thecomponents of the lightning protection system and other conductiveelements in the structure.

31


IEC 62305:2010-2012, Part 3

5.2 Air-termination System (ATS)

5.2.2 Positioning

Air-termination components installed on a structure shall be located at corners,

exposed points and edges (especially on the upper level of any facades) in

accordance with one or more of the following methods.

Acceptable methods to be used in determining the position of the air-

termination system include:

the protection angle method;

the rolling sphere method;

the mesh method.



IEC 62305:2010-2012, Part 3

Air-termination System (ATS)


Class of

LPS

Protection method Down-

Conductors

distances

(m)

Rolling

sphere

r (m)

Protection angle

a (°)

Mesh

size

w (m)

I 20 5 x 5 10

II 30 10 x 10 10

III 45 15 x 15 15

IV 60 20 x 20 20

Note: The protection angle method has its limitations (height)


Standards and Norms


(translation)

5.2 External lightning protection

Based on the DIN EN 62305-3 (VDE 0185-305-3) lightning protection

standard, roof-mounted photovoltaic power supply systems should be

protected against direct lightning strikes by means of isolated air-

termination systems, as far as practicable.

NOTE If a photovoltaic power supply system is newly installed

on a structure, the existing electrical installation may have

to be adapted.

34


IEC 62305:2010-2012, Part 3

Annexure E

103

E.5.1.2 Isolated LPS

An isolated external LPS should be used when the flow of the lightning current

into bonded internal conductive parts may cause damage to the structure or its

contents.

NOTE 1: The use of an isolated LPS may be convenient where it is predicted that

changes in the structure may require modifications to the LPS.

An LPS that is connected to conductive structural elements and to the

equipotential bonding system only at ground level, is defined as isolated

according to 3.3.

An isolated LPS is achieved either by installing air-termination rods or masts

adjacent to the structure to be protected or by suspending overhead wires

between the masts in accordance with the separation distance of 6.3.


Direct connection of roof-mounted structures

Partial lightning currents inside the structure

EB

EB

MEBServer

PC PC

PC PC

FDB: Floor Distribution Board; MEB: Main Equipotential Bonding; EB: Equipotential Bonding

FDB

FDB

104

PV Panel / Structure


Protection of roof-mounted structures with isolated air-

termination system

EB

EB

MEBServer

FDB

PV Panel /

Structure

PC PC

PC PCFDB

FDB: Floor Distribution Board; MEB: Main Equipotential Bonding; EB: Equipotential Bonding

Lightning current

discharged from the

outside

106


Separation distance for PV modules

18.02.13 / 4033_E_1Photovoltaic – External lightning protection

s

s

a


Inductive coupling of lightning currents into PV

modules depending on the distance from the module

lightning

protection cable

variation of the

distance

impulse current

generator

150 kA 10/350 µs

PV module with

short-circuited

output terminals

measurement

of the induced

impulse current

0.5 m

20.02.13 / 4216_E_1Photovoltaic – Causes


Inductive coupling of lightning currents into PV

modules depending on the distance from the module

20.02.13 / 4216_E_4

Ii[kA]

0.25 0.5 0.75 1.0 1.25 1.5 1.75

time [ms]

distance 0.5 m

distance 1 m

distance 2 m

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0

I10/350

[kA]

0.25 0.5 0.75 1.0 1.25 1.5 1.75

time [ms]

-10

0

10

20

30

40

50

60

0

induced impulse

currents in case of

different distances

primarily fed lightning

current



IEC 62305:2010-2012, Part 3

Down-conductor system

94

5.3 Down-conductor systems

5.3.1 General

In order to reduce the probability of damage due to lightning current flowing in

the LPS, the down-conductors shall be arranged in such a way that from the

point of strike to earth:

a) several parallel current paths exist;

b) the length of the current paths is kept to a minimum;

c) equipotential bonding to conducting parts of the structure is

performed according to the requirements of 6.2.

NOTE 1 Lateral connection of down-conductors is considered to be good

practice. The geometry of the down-conductors and of the ring conductors

affects the separation distance (see 6.3).


5.3 Down-conductor systems

5.3.1 General

NOTE 2 The installation of as many down-conductors as possible, at

equal spacing around the perimeter interconnected by ring conductors,

reduces the probability of dangerous sparking and facilitates the

protection of internal installations (see IEC 62305-4).

This condition is fulfilled in metal framework structures and in reinforced

concrete structures in which the interconnected steel is electrically

continuous.

Typical values of the preferred distance between down-conductors are

given in Table 4.

Standards and Norms


(translation)

42


Standards and Norms

IEC 62305:2010-2012, Part 3

21

5.4 Earth-termination system

5.4.1 General

When dealing with the dispersion of the lightning current (highfrequency behaviour) into the ground, whilst minimizing any potentiallydangerous overvoltages, the shape and dimensions of the earth-termination system are the important criteria.

In general, a low earthing resistance (if possible lower than 10 Ω whenmeasured at low frequency) is recommended. From the viewpoint oflightning protection, a single integrated structure earth-terminationsystem is preferable and is suitable for all purposesIn general, a low earthing resistance is recommended. Earth-terminationshall be bonded in accordance with the requirements of 6.2.


Arrangements of earth electrodes

as per IEC 62305-3:2010

96

type A

Horizontal (radial) earth electrode per down conductor

type B

Ring earth electrode (at least 80% in soil) Foundation earth electrode (DIN 18014)

connector connector

min. 5 m

at least 0.5 m

at least 2.5 m

9 m

recommended

0.5 m

at least1 m

Vertical earth electrode (earth rod) per

down conductor


Standards and Norms


(translation)

4.4 Lightning current distribution in a ground-mounted PV system

Depending on the relevant class of LPS, the type of earth-termination system

and the soil resistivity, SPDs with a lightning current discharge capacity of a

some kA are sufficient for ground-mounted PV systems.

The sample calculations are based on a mesh size of 20 m x 20 m. In case of

larger mesh sizes, it is to be expected that higher partial lightning currents flow

via the d.c. SPDs.

45


Internal Lightning Protection

Classification of Arresters

SCI Patented arresters for PV systems

Equipotential Bonding

Data Acquisition



Standards and Norms


(translation)

5.6 Selection of surge protective devices

5.6.2 Type 1 surge protective device, lightning current carrying capability

It is recommended to use Type 1 surge protective devices on the d.c.

side of photovoltaic power supply systems, if

an external lightning protection system is installed and

the required separation distance from elements of the

photovoltaic power supply system is not kept.

47


Assumed lightning current distribution in the event of a

direct lightning strike

100%

50%

50%

230/400 V

6 mm2 Cu

31.07.13 / 4015_E_4Photovoltaic – Surge protection

SEB

M M

MEB

GJB

SEB: Service Entrance Box; MEB: Main Earthing Busbar; GJB: Generator Junction Box; M: Meter

type 1

combined arrester


Maximum values of lightning parameters according to

LPL (lightning protection level)


Ref.: IEC 62305-1:2010, Table 3 (extract)

29.10.13 / 6006_E_1

First positive impulse Lightning protection level (LPL)

I II III-IV

Peak current I (kA) 200 150 100

Specific energy W/R (MJ/Ω) 10 5.6 2.5

Charge Q short (C) 100 75 50

Time parameters T1/T2 (µs/µs) 10/350


Inductive coupling

05.08.13 / 1500_E_6

230/400 V SEB

M M

MEB

GJB


SEB: Service Entrance Box ; MEB: Main Earthing Busbar; GJB: Generator Junction Box; M: Meter


wave form [µs] 10/350 8/20

imax [kA] 100 20

Comparison of test currents

Photovoltaic – Surge protection 30.07.13 / 916_E_3

i [kA]

1

0

20

40

50

60

80

100

t [ms]

20 400 600 800 1000

21

350

test impulse current for

lightning current

arresters

2test impulse

current for

surge arresters

200

Ref.: IEC 61643-11


Video

Impact on the electrical installation


Standards and Norms


(translation)

5.6 Selection of surge protective devices

5.6.1 General

Surge protective devices for the d.c. side must be chosen in such a way

that they enter a safe state even in case of a short-circuit without

presenting a risk of fire resulting from overload and arc formation.

The manufacturer of the surge protective devices provides evidence that

the switching device integrated in the surge protective device has the

switching capacity required for the conditions at the place of installation.

53


Patented SCI principle

… suitable for PV applications (d.c.)

Combined disconnection and short-circuiting device with safe electrical

isolation in the protection module prevents fire damage resulting from d.c.

switching arcs (patented SCI principle).

11.12.13 / 8035_E_1

switching phases:

Original

state

1.Tripping of

the

disconnector

2.Active

arc

extinction

3.Safe

electrical

isolation

Three-step d.c. switching device

(patented SCI principle)

SCI SCI SCI SCI

Photovoltaic – Surge protection


…enter a safe state even in case of a short-circuit without

presenting a risk of fire

with Short-Circuit Interruptwithout Short-Circuit Interrupt

Video “Disconnection with SCI“Video “Disconnection without SCI“

26


Protection concept for system monitoring

NTBA modem

data

acquisition

unit

06.08.13 / 3532_E_5Photovoltaic – data acquisition


Lightning Protection Concepts

PV Systems with NO external lightning protection

PV Systems with BONDED external lightning protection

PV Systems with ISOLATED lightning protection

57


LIGHTNING PROTECTION CONCEPTS

PV system with NO external lightning protection system

30

Type 2

Type 2



PV system with NO external lightning protection system

29

Type 1+2

Type 1+2

Type 1+2



PV system with BONDED external lightning protection system

32

Type 1+2



PV system with BONDED external lightning protection system

`

31

Derated Type1+2

Type 1+2



PV system with ISOLATED external lightning protection system

SAPVIA - Risk Mitigation through Protection 34

Type 2



PV system with ISOLATED external lightning protection system

33

Type 2

Type 2


DEHNconcept

Risk Assessments

Detailed Design of LPS & Earthing Systems


PV system with

ISOLATED external LPS

65


Questions?

SAPVIA - Risk Mitigation through Protection

ALEXIS. W. BARWISE

Managing Director (B. Eng)

DEHN AFRICA (Pty) Ltd.

Tel. +27 11 704 1487

[email protected]

www.dehn-africa.com

66

Risk Mitigation through Protection - Solar Dynamix Mitigation through Protection Agenda Damages to...

Documents

Transcript of Risk Mitigation through Protection - Solar Dynamix Mitigation through Protection Agenda Damages to...