Lightning System And Risk Analysis Study

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY

00

07-DEC-17

AFC

APPROVED FOR CONSTRUCTION

ST

MH

MSELMI

B

28-NOV-17

IFR

ISSUED FOR REVIEW

ST

MH

MSELMI

A

27-NOV-17

IDC

ISSUED FOR IDC

ST

MH

MSELMI

REV

DATE

STATUS

ISSUE PURPOSE

ISSUED BY

REVIEWED BY

APPROVED BY

COMPANY DOCUMENT ATTRIBUTES Company Code

Contract Territory Code

Originator Code

Facility Code

System Code

Discipline

Document Type

Sequence Number

8015

0151

EPPM

12

880

EL

CC

20001

This document is property of the COMPANY and it shall not be disclosed to third parties, or reproduced, without permission of the COMPANY.

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY COMPANY Doc. No.: 8015-0151-EPPM-12-880-EL-CC-20001 CONTRACTOR Doc. No.: R1117-CLC-EL-01-204

Rev.:

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DOCUMENT REVISION HISTORY SHEET REV

STATUS

DATE ISSUED

UPDATE / AMENDMENT DETAILS

A

IDC

27-NOV-17

ISSUED FOR DISCIPLINE CHECK

B

IFR

28-NOV-17

ISSUED FOR REVIEW

00

AFC

07-DEC-17

APPROVED FOR CONSTRUCTION

Status: AFC 2 of 10

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY COMPANY Doc. No.: 8015-0151-EPPM-12-880-EL-CC-20001 CONTRACTOR Doc. No.: R1117-CLC-EL-01-204

Rev.: Page:

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Status: AFC 3 of 10

CONTENT 1. PURPOSE................................................................................................................................ 4 2. APPLIED STANDARDS ....................................................................................................... 4 3. LIGHTNING RISK ASSESSMENT STUDY ...................................................................... 4 3.1. Lightning strike frequency (Nd) ....................................................................................... 4 3.2. Lightning ground flash density (Ng) ................................................................................ 4 3.3. Equivalent collection area of a structure (Ae) ................................................................ 5 3.4. Determination of location factor C1 ................................................................................ 5 3.5. Tolerable lightning frequency (Nc) .................................................................................. 5 3.6. Selection of the Protection Level ..................................................................................... 6 3.7. Result of lightning risk assessment study ....................................................................... 6 3.8. Calculation ......................................................................................................................... 7 3.9. Conclusions ........................................................................................................................ 8 4. CALCULATION METHOD FOR 132KV SWITCHYARD .............................................. 8 4.1. Referenced Project Documents: ...................................................................................... 8 4.2. Assumptions....................................................................................................................... 8 4.3. Calculation ......................................................................................................................... 8 4.4. Conclusions ...................................................................................................................... 10

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY COMPANY Doc. No.: 8015-0151-EPPM-12-880-EL-CC-20001 CONTRACTOR Doc. No.: R1117-CLC-EL-01-204

1.

Rev.:

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Page:

Status: AFC 4 of 10

PURPOSE

The purpose of this study is to perform lightning risk assessment evaluation study for the buildings in accordance with NFPA 780, for the EPC Well Pads and Oil Gathering System at the West Qurna (Phase 2) Contract Area. 2.

APPLIED STANDARDS

NFPA 780 Standard for the installation of lightning protection system IEC 62305 Protection against lightning IEEE 998 3.

IEEE Guide for Direct Lightning Stroke Shielding of Substations

LIGHTNING RISK ASSESSMENT STUDY

The Lightning Risk Assessment study has been done to assist the building owner or architect/engineer in determining the risk of damage due to lightning. The methodology considers only the damage caused by a direct strike to the building or structure to be protected and the currents flowing through the lightning protection system. 3.1.

Lightning strike frequency (Nd)

As per annexure L of NFPA 780 Nd= (Ng) (Ae) (C1) (10-6) Where: Nd: the yearly lightning strike frequency to the Structure Ng: the yearly average flash density in the region where the structure is located Ae: the equivalent collection area of the structure (m²) C1: location factor 3.2.

Lightning ground flash density (Ng)

The lightning ground flash density is expressed in terms of ground strokes per square kilometer per year and should be determined by measurement. If the lightning ground flash density Ng is not known, it may be estimated using the following relationship (IEC 62305-2, § A.1): Ng=0.1*Td per km² per year, Where Td is the number of thunderstorm days per year obtained from isokeraunic maps. Particularly for Iraq, Td = 15 (as given in paragraph 7.3 of document 8015-0151-EPPM-12-880EL-SP-00001_specification for earthing and lightning protection system). Ng = 0.1 * 15 = 1.5 strokes per km² per year

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY COMPANY Doc. No.: 8015-0151-EPPM-12-880-EL-CC-20001 CONTRACTOR Doc. No.: R1117-CLC-EL-01-204

3.3.

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Status: AFC 5 of 10

Equivalent collection area of a structure (Ae)

Ae refers to the ground area having the same yearly direct lightning flash probability as the structure. In fact, it is an increased area for the structure that includes the effect of the height and location of the structure (NFPA 780 § L.4). The equivalent collection area, Ae, of a structure is the area obtained by extending a line with a slope of 1 to 3 from the top of the structure to ground completely around the structure. The equivalent collection area of a rectangular structure with length L, width W, and height H is as follows: Ae = LW +6H (L+W) +π9H2 Where the equivalent collection area of a structure totally covers another structure, that structure is disregarded and when the collection areas of several structures are overlapped, the corresponding common collection area is considered as a single collection area. 3.4.

Determination of location factor C1

Value of location factor C1 is selected based on table L.4.2 of NFPA 780 Relative Structure Location

C1

Structure located within a space containing 0.25 structures or trees of the same height or taller.

3.5.

Structure surrounded by smaller structures

0.50

Isolated structure

1.00

Isolated structure on a hilltop.

2.00

Tolerable lightning frequency (Nc)

The tolerable lightning frequency (Nc) is a measure of the damage risk to the structure including factors affecting risks to the structure, environment, and monetary loss. The tolerable lightning frequency is expressed by the following formula: 𝑵𝒄 =

𝟏.𝟓𝐱𝟏𝟎−𝟑 𝐂

Where: C = (C2) (C3) (C4) (C5) (a) Determination of construction coefficient C2 (refer to table L.5.1.2(a) of NFPA 780)

Structural Coefficients C2 Metal Roof

Nonmetallic Roof

Flammable Roof

Metal

0.5

1.0

2.0

Nonmetallic

1.0

1.0

2.5

Flammable

2.0

2.5

3.0

Structure

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY COMPANY Doc. No.: 8015-0151-EPPM-12-880-EL-CC-20001 CONTRACTOR Doc. No.: R1117-CLC-EL-01-204

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Status: AFC 6 of 10

(b) Determination of structure contents coefficient C3 (refer to table L.5.1.2 (b) of NFPA 780)

Structure Contents

C3

Low value and nonflammable

0.5

Standard value and nonflammable

1.0

High value, moderate flammability

2.0

Exceptional value, flammable, computer or electronics Exceptional value, irreplaceable cultural items

3.0 4.0

(c) Determination of Structure Occupancy Coefficient C4 (refer to table L.5.1.2 (c) of NFPA 780)

Structure Occupancy

C4

Unoccupied

0.5

Normally occupied

1.0

Difficult to evacuate or risk of panic

3.0

(d) Determination of lightning consequence coefficient C5 (refer to table L.5.1.2 (d) of NFPA 780)

Lightning Consequence Continuity of facility services not required, no environmental impact Continuity of facility services required, no environmental impact Consequences to the environment 3.6.

C5 1.0 5.0 10.0

Selection of the Protection Level

The tolerable lightning frequency (Nc) is compared with the expected lightning frequency (Nd). The result of this comparison is used to decide if a lightning protection system is needed. If Nd ≤ Nc, a lightning protection system (LPS) can be optional. If Nd > Nc, a lightning protection system should be installed. 3.7.

Result of lightning risk assessment study

The result of lightning risk assessment study for buildings is shown in following table. Proper lightning protection system in accordance with the applicable standards shall be provided for the buildings that have been identified with the requirement of LPS in following table.

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY COMPANY Doc. No.: 8015-0151-EPPM-12-880-EL-CC-20001 CONTRACTOR Doc. No.: R1117-CLC-EL-01-204 No

Rev.:

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Status: AFC 7 of 10

1

2

12-830-ESS-11/1A

12-430-SIH-11/1A

Building Name

SUBSTATION

SIH

Structure Type

containerized

containerized

NO

NO

W

8.0

3.0

L

42.0

10.5

H

7.2

4.2

3962

871

Lightning Flash density (Ng)

1.5

1.5

Location factor (C1)

0.25

0.25

0.00149

0.00033

0.5

0.5

3

3

0.5

0.5

5

5

3.75

3.75

0.0004

0.0004

YES

NO

Building No.

Manned

Building Size

Equivalent Collection Area (Ae)

Lightning strike frequency (Nd) Structural coefficient (C2) Structure contents coefficient (C3) Structure Occupancy Coefficient (C4) Lightning consequence coefficient (C5) C Tolerable lightning frequency (Nc) LPS required (Yes/No)

3.8.

Calculation

Nd= 0.00149 and Nc= 0.0004. The lightning protection efficiency (E) E= 1- (Nc/Nd) = 73% Based on efficiency calculation, protection level selected as Level –IV (Refer table below). Protection Level

Lightning Protection Efficiency

I

98%

II

95%

II

90%

IV

80%

Therefore, the maximum distance between two air terminations mesh is 20m (Refer table below). Protection Level

h (m) R (m)

20

30

45

60

α0

α0

α0

α0

Mesh Width (m)

I

20

25

*

*

*

5

II

30

35

25

*

*

10

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY COMPANY Doc. No.: 8015-0151-EPPM-12-880-EL-CC-20001 CONTRACTOR Doc. No.: R1117-CLC-EL-01-204

Rev.: Page:

III

45

45

35

25

*

15

IV

60

55

45

35

25

20

00

Status: AFC 8 of 10

* Rolling sphere and mesh methods only apply in these case.

The average down conductor spacing considered is 25m (refer to table below).

3.9.

Protection Level

Average distance (m)

I

10

II

15

II

20

IV

25

Conclusions

The maximum horizontal distance between two air terminations mesh is 20 meters and the average down conductor spacing considered is 25 meters. 4.

CALCULATION METHOD FOR 132kV SWITCHYARD

The method being used to determine lightning protection requirements for WP 11/1A Substation is the electrogeometric model by the rolling sphere method per IEEE Standard 998, “IEEE Guide for Direct Lightning Stroke Shielding of Substations”. 4.1.

Referenced Project Documents:

8015-0151-EPPM-12-841-EL-DD-20001 ELECTRICAL EQUIPMENT LAYOUT WP 11/1A SUBSTATION 4.2.

Assumptions

Average surge impedance (ZS) of a shield wire or structure is assumed to be 300 ohms, typically used by IEEE 998 for operating voltages 132kV and above. 

The height of the shielding wire is assumed to be 13 meters, and the height of equipment shall be protected is 5.4 meters. 

4.3.

Calculation

The Basic Impulse Insulation Level (BIL) for the equipment in the 132kV switchyard is 650kV (BIL). Therefore, the Stroke Current (IS) for the 145kV equipment is calculated to be: 𝐈𝐬 =

𝐁𝐈𝐋∗𝟏.𝟏 𝐙𝐬 /𝟐

= 𝟒. 𝟕𝟕𝐤𝐀

BIL

-

Basic Impulse Insulation Level = 650 kV

ZS

-

Average Surge Impedance = 300 ohms

The Strike Distance (S) for the 145kV equipment is calculated to be: S = 8 * k *(IS) 0.65 = 22.08 meters for shield wires

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY COMPANY Doc. No.: 8015-0151-EPPM-12-880-EL-CC-20001 CONTRACTOR Doc. No.: R1117-CLC-EL-01-204

k

-

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Status: AFC 9 of 10

Coefficient for striking distance to a Shield Wire = 1.0

A strike distance of 22.08 meters is used for all calculations with respect to 145kV equipment. A worst case calculation for the 132kV switchyard using the one Shield Wire scenario at the maximum bus height and minimum shield wire height is analyzed:

H

-

Shield Wire Height= 13 meters

A

-

Bus Height = 5.4 meters

S

-

Strike Distance = 22.08 meters

T = √𝐒 𝟐 — (𝐒 − 𝐀)𝟐 = 14.47 meters R = √𝐒 𝟐 — (𝐒 − 𝐇)𝟐 = 20.12 meters C = R -T = 5.66 meters C

-

Horizontal distance between shield wire and bus

A worst case calculation for the 132kV switchyard using the two Shield Wire scenarios at the maximum bus height and minimum shield wire height is analyzed:

ENGINEERING, PROCUREMENT & CONSTRUCTION FOR PRODUCTION WELL PAD 11/1A AND ASSOCIATED GATHERING SYSTEM EXPANSION AT THE WEST QURNA (PHASE 2) CONTRACT AREA

LIGHTNING SYSTEM AND RISK ANALYSIS STUDY COMPANY Doc. No.: 8015-0151-EPPM-12-880-EL-CC-20001 CONTRACTOR Doc. No.: R1117-CLC-EL-01-204

H

-

Shield Wire Height= 13 meters

A

-

Bus Height= 5.4 meters

S

-

Strike Distance= 22.08 meters

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Status: AFC 10 of 10

𝐃 = 𝐇 − 𝐀 = 𝟕. 𝟔 meters 𝐄 = 𝐒 − 𝐃 = 𝟏𝟒. 𝟒𝟖 meters 𝐋 = √𝐒 𝟐 — 𝐄𝟐 = 𝟏𝟔. 𝟔𝟕 meters 𝐗 = 𝟐 ∗ 𝐋 = 𝟑𝟑. 𝟑𝟑 meters L

-

Half the separation between Shield Wires

X

-

Maximum allowable separation between two shield wires

4.4.

Conclusions

Therefore, since the maximum horizontal distance between shield wire and bus for one shield wire is 5.66 meters and the maximum allowable distance between two shield wires for protection from vertical strokes is 33.33 meters, all 132kV switchgear and transformer are properly protected from lightning strokes by the shield wires.