5108879 14 01 1000 rev0 transmission protection

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33 kV Interconnection of Al Ghail and Al Hamra Power Plants33kV Transmission System Protection Application

Private and confidentialAtkins 5108879/14.01/1000/Rev 0

Notice

This document and its contents have been prepared and are intended solely for AL GHAIL POWER LLCsinformation and use in relation to protection application of their 33kV transmission system

ATKINS ENERGY assumes no responsibility to any other party in respect of or arising out of or in connectionwith this document and/or its contents.

Document History

Job number: 5108879 Document ref: 5108879/14.01/1000

Revision Purpose description Originated Checked Reviewed Authorised Date

Rev 0 First Version GV VAM KS JS 20/04/12


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Private and confidentialAtkins 5108879/14.01/1000/Rev 0 4

1. Introduction

Al Ghail Power LLC operates two power plants in the Emirate of Ras Al Khaimah. With the approval ofGovernment of Ras Al Khaimah, Al Ghail Power LLC intends to interconnect both power plants with 33KVTransmission line from Al Ghail area to Al Hamra area in Ras Al Khaimah. This 33kV transmission system is

hybrid line comprising sections of underground cable and overhead lines. The existing 33kV switchgearpanel houses Main and Backup Protections. This report examines suitability of existing Protections at both AlGhail and Al Hamra ends and suggest suitable Protection requirement for the hybrid transmissionapplication.

1.1. Abbreviations

The abbreviations used in this document are as follows:

OHL - Over Head Line

AAAC - All Aluminium Alloy Conductor

UG Cable - Underground Cable

IED - Intelligent Electronic Device

+Seq Imp - Positive sequence impedance in Ohms/kM

Zero Seq imp - Zero sequence impedance in Ohms/kM

KN - Residual compensation factor

P.U. impedance - Per Unit Impedance

2. Application CheckThis section examines the application check for suitable protection for the 33kV Transmission system. The33kV Transmission system connecting Al Ghail and Al Hamra Power stations is hybrid line comprisingsections of underground cables and over head lines. Details are as below

Al Ghail end Al Hamra end

Al Ghail end: 1Cx500sq.mm, Cu; 1 run; 2 Circuits; Length=1km

33kV OHL AAAC, Single conductor; double circuit; Length=45km

Al Hamra end: 1Cx500sq.mm, Cu; 1 run; 2 Circuits; Length=6.2km

Cables

Over Head Line


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Z1 P.U. impedance =

=..= 1.62 P.U.

Z0 = Zero Seq Imp of line = (0.623+j0.244) x1+ (0.2234+j1.4203) x45+ (0.623+j0.244) x6.2

Z0 = Zero Seq Imp of line = (14.54+j 65.67) = 67.2677.51

Z0 P.U. impedance =

=..= 6.17 P.U.

Transformer impedance = 12.72% at 31.5 MVA.

On 100MVA Base, transformer impedance =.. 100= 40.38% = 4.038 P.U.

Effective impedance when two transformers are operated in Parallel = 2.109 P.U

Al Ghail end

Zone 1 Settings = 80% of line length = 0.8 x 52.2 = 41.76kM

This corresponds to 1 Km of Underground cable plus 40.76kM of Overhead Line

Z1 = +Seq Imp of line = (0.0521+j0.144)x1+ (0.0754+j0.3616)x40.76 = (3.12+j14.88)

Z1 = +Seq Imp of line = 15.2078.15 =..= 1.39 P.U. ----------------------------------(1)

Z0 = Zero Seq Imp of line = (0.623+j0.244) x1+ (0.2234+j1.4203) x 40.76 = (9.73+j58.135)

Z0 = Zero Seq Imp of line = 58.9480.5 =..= 5.41 P.U.--------------------------------(2)

KN Residual compensation factor =

1= .. 1= 0.96------(3)

Zone 2 Settings = 150% of line length = 1.5 x 52.2 = 78.3kM

Z1 = +Seq Imp of line = 1.5 x (3.77+j 17.31) = (5.655+j25.965) = 26.5777.71

Z1 = +Seq Imp of line = ..= 2.44 P.U.---------------------------------------------------------(4)

Z0 = Zero Seq Imp of line = 1.5 x (14.54+j 65.67) = (21.81+j98.505) = 100.8977.51

Z0 = Zero Seq Imp of line = =.. = 9.264 P.U.------------------------------------------------(5)

KN Residual compensation factor =

1= .. 1= 0.93---(6)

Zone 3 Settings = 200% of line length = 2 x 52.2 = 104.4kM


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Table 3. Differential Relay Vendor List

Vendor Type of Protection

ABB RED 670

Alstom P54x series

Siemens 7SD 610

Schweitzer EngineeringLaboratories, Inc.

SEL-411L

Toshiba GRL100

2.2.3.1. CT and VT requirements

CT requirement

The performance of a protection function will depend on the quality of the measured current signal.Saturation of the current transformer (CT) will cause distortion of the current signal and can result in a failureto operate or cause unwanted operations of some functions. Consequently CT saturation can have aninfluence on both the dependability and the security of the protection. The protection IED should be designedto permit heavy CT saturation with maintained correct operation.

The current transformer ratio is mainly selected based on power system data for example, maximum load.However, it should be verified that the current to the protection is higher than the minimum operating valuefor all faults that are to be detected with the selected CT ratio. The minimum operating current is different fordifferent functions and normally settable so each function should be checked. The current error of the currenttransformer can limit the possibility to use a very sensitive setting of a sensitive residual overcurrent

protection. If a very sensitivesetting of this function will be used it is recommended that the current transformer should have an accuracy

class which have an current error at rated primary current that is less than 1% (for example, 5P). If current

transformers with less accuracy are used it is advisable to check the actual unwanted residual current duringthe commissioning.

With regard to saturation of the current transformer all current transformers of high remanence and lowremanence type that fulfill the requirements on the rated equivalent secondary e.m.f.VKnee can be used.

Detailed CT requirement calculations will be done after finalizing the following details

1. Type of protection to be used2. Maximum fault level in the system3. CT secondary resistance4. Lead resistance5. CT ratio6. Burden of the IED used


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VT requirement

The performance of a protection function will depend on the quality of the measured input signal. Transientscaused by capacitive voltage transformers (CVTs) can affect some protection functions. Magnetic orcapacitive voltage transformers can be used.

The capacitive voltage transformers (CVTs) should fulfill the requirements according to the IEC 600445

standard regarding ferro-resonance and transients. The ferro-resonance requirements of the CVTs are

specified in chapter 7.4 of the standard.The transient responses for three different standard transient response classes, T1,T2 and T3 are specifiedin chapter 15.5 of the standard. CVTs according to all classes can be used.Most of the new generation protection IED has effective filters for these transients, which gives secure andcorrect operation with CVTs.

2.2.3.2. Additional Functions

Broken Conductor detection 46BC

The majority of faults on a power system occur between one phase and ground or two phases and ground.These are known as shunt faults and arise from lightning discharges and other over voltages which initiateflashovers. Alternatively, they may arise from other causes such as birds on overhead lines or mechanicaldamage to cables etc. Such faults result in an appreciable increase in current and hence in the majority ofapplications are easily detectable.Another type of unbalanced fault that can occur on the system is the series or open circuit fault. These canarise from broken conductors, maloperation of single phase switchgear, or single-phasing of fuses. Seriesfaults will not cause an increase in phase current on the system and hence are not readily detectable bystandard protection. However, they will produce an unbalance or asymmetry between currents in the threephases. This can be detected by almost all new generation IEDs. Generally this function is integrated with inthe Main protection IED.

Under Voltage Protection 27

In the majority of applications, under voltage protection function will be available to detect loss of voltageconditions. The threshold value selected should be less than single phase voltage depressions due to earthfaults. The voltage threshold setting for the under voltage protection should be set at some value below thevoltage excursions which may be expected under normal system operating conditions. This threshold isdependent upon the system in question but typical healthy system voltage excursions may be in the order of-10% of nominal value.Time delay shall depend upon the time for which the system is able to withstand a depressed. This can bedetected by almost all new generation IEDs. Generally this function is integrated with in the Main protectionIED.


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3. Conclusion

From the foregoing sections, we wish to infer the following

1. Existing Protections Solkor N- 7SG813 and MBCI are not suitable and hence have to be replaced.

2. Distance Protection is not suitable for this application

3. Line differential protection working on digital communication technology will be best suited for thisapplication. Major IED manufacturers in the market Viz ABB, Siemens, Alstom, SEL, etc. have linedifferential protections in their product range.

4. Other monitoring and protection functions Viz. Broken conductor and under voltage functions can beintegrated with the main protection.

5. Existing BACKUP Protection can be retained.

6. New IED can be fitted in the existing switchgear panel and interfaced to existing tripping circuits aftersite confirmation.


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Appendices


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Appendix A. Single Line Diagram of33 kV Transmission System


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GENERATOR - 1

11kV, 33MW

GENERATOR - 2

11kV, 33MW

TRANSFORMER 1

11kV/33kV

YNd11

TRANSFORMER 2

11kV/33kV

YNd11

VT

VT

VT

VT

TRANSFOR

11kV/33

YNd1

TRANSFOR

11kV/33

YNd1

1km CABLE

1km CABLE

6.2km CABLE

6.2km CABLE

21

ZONE 1

ZON

DISTANCE PROTECTION SOLUTION

OVER HEAD LINE

OVER HEAD LINE

11kV AL GHAIL

SUBSTATION33kV AL GHAIL

SUBSTATION

33kV AL HAMRA

SUBSTATION

TIME

TIME

ZONE 1

ZONE 2

ZONE 3

OUTGOING

11kV FEEDERS

DISTANCE PROTECTION AT

AL HAMRA END MAY ENCROACH

INTO 11kV SYSTEM -

NOT DESIRABLE

ZOM - ZERO SEQUENCE MUTUAL

IMPEDANCE IMPACT ZONE

MEASUREMENTS

21 21

21

8.2km CABLE

33kV A

SUBS

ZOM


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UNIT PROTECTION SOLUTION

GENERATOR - 1

11kV, 33MW

GENERATOR - 2

11kV, 33MW

TRANSFORMER 1

11kV/33kV

YNd11

TRANSFORMER 2

11kV/33kV

YNd11

VT

VT

VT

VT

1km CABLE

1km CABLE

6.2km CABLE

6.2km CABLE

87L

OVER HEAD LINE

OVER HEAD LINE

11kV AL

GHAIL

SUBSTATION

33kV AL GHAIL

SUBSTATION

33kV AL HA

SUBSTAT

87L 87L

87L

OUTGOING

11kV FEEDERS

ZOM - ZERO SEQUENCE MUTUAL

IMPEDANCE DO NOT IMPACT ZONE

MEASUREMENT

OPTIONAL

OPTIONAL

OPTIONAL

OPTIONAL

DIGITAL COMMUNICATION INTERFACE

UNIT PROTECTION

ZONE

UNIT PROTECTION

ZONE

DIGITAL COMMUNICATION INTERFACE


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Appendix C. Red/Green Markups


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Appendix D. Sample Specification


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The IED shall be suitable for protection, control and monitoring of

overhead lines and cables for all voltage levels in solidly or impedance

grounded networks. The IED shall be of phase-segregated design for two and up

to five line ends; it shall also be possible to apply up to two power transformers

in the protected zone. It shall even be possible to apply a small power

transformers connected to a line tap without having a line differential IED

installed at the tap and still get selectivity with overcurrent protections on the

low voltage side of the power transformer. The IED shall be based on advanced

and proven algorithms and an easy and efficient upgrade of the IED

functionality shall be possible. A tool for user-friendly engineering and

disturbance handling shall be available. It shall be possible to integrate

protection and control functionality for several objects in the IED e.g. back-up

protection for power transformers and reactors. The IED shall have complete

functionality for single or multi-breaker arrangements with single or three phase

tripping. At least five independent parameter setting groups shall be included.

The IED shall have extensive self-supervision including analog channels. In

order to achieve cost effective engineering, testing and commissioning shall

preconfigured, ready to use IEDs for different applications be available. If

needed, it shall be easy to modify the configuration. At new installations or at

extensions and replacements in existing installations shall it be possible to

integrate the IED into substation automation or monitoring system or use theIED as a stand-alone multifunction unit.

Sample specification

It shall be possible to equip the IED with a large HMI for local operation

of breakers and disconnectors and visualization of single line diagrams with

positions indications of included breakers and disconnectors. For the line

differential protection shall individual phase currents in 1 breaker and

Multi-breaker arrangements are connected to the IED without external

summation for improved through fault stability. A restrained dual biased


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operate characteristic shall be used and the highest phase current in any line

shall be utilized as bias current. Charging current compensation for increased

sensitivity for long lines or cables shall be included. The IED shall be suitable

for multiplexed; route switched or dedicated fibre communication networks.

Two time synchronization methods shall be available, the echo-method when

channels with stable and equal delays in both directions are used and GPS to be

used in switched networks with unequal channel delays in both directions.

The communication channel shall be continuously monitored and an automatic

switchover to a redundant channel shall be possible. For line differential

communication it shall be possible to select between a master-master system or

a master-slave system depending on the functional or economic requirements.

An automatic switchover to master-slave communication shall take place

if an interruption occurs in one communication channel in a master-master

communication system. It shall be possible to transfer eight binary signals

between the IEDs. Communication modules for dedicated fibre communication

for short and long distances (>60 km) shall be available. Testing of the completeline differential scheme shall be possible to perform from one freely selected

IED included in the protection scheme. A high impedance differential

protection for tee-feeders shall be possible to include in the IED. A back-up

high speed full-scheme distance protection with at least three zones shall

be possible to include in order to get fault clearance in case of communication

failure, it shall be possible to have the distance protection continuously inoperation or only released for operation at communication failure.

The distance protection shall have a characteristic that will give load

encroachment discrimination and load current compensation of the reactance

line in the first zone in order to avoid overreach. It should be possible to set

each distance protection zone in forward, reverse or non-directional mode. Each

zone shall have individual settings of reactive and resistive reach. No trip for

reverse faults is accepted for a forward looking zone as long as the requirements


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on the CTs are fulfilled. Separate phase selection and automatic switch into

fault logic shall be included.

For communication with a distance protection at the remote end shall

permissive, blocking and intertrip scheme communication logic be included.

Power swing detection function and current reversal and weak-end infeed logic

shall be available. It shall be possible to include instantaneous overcurrent

functions for phase and earth faults and time delayed directional/non-directional

overcurrent functions with inverse and definite time characteristic with at least

three steps for phase and earth faults. Scheme communication logic and current

reversal and week-end infeed logic for directional residual overcurrent

protection shall be possible to include. Other current functions such as thermal

overload with alarm and trip steps and breaker failure protection with short reset

time shall also be possible to include in the IED. Stub protection for multi-

breaker arrangements and breaker pole discordance protection shall be

available. Over and under-voltage protection with at least two steps, over and

under-frequency functions and rate-of-change frequency functions shall also bepossible to include in the IED.

For secondary system supervision shall fuse failure and current circuit

supervision is available. The IED shall be provided with programmable logic

for tripping and indications as well as a high number of logic blocks and timers

for user adaptation. Apparatus control for control and supervision of breakers,

disconnectors and earthing switches with interlocking modules for differentswitchgear arrangements should be possible to include.

Synchro/energizing check and synchronizing function as well as auto-

reclosing function for high-speed and/or delayed auto-reclosing for single or

multi-breaker arrangements shall be available. Monitoring functions such as

service values for U, I, P, Q, S, f and power factor shall be included and

supervision of mA input signals from transducers shall be possible to include.


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Pulse counter logic for counting of externally generated binary pulses from an

energy meter shall be available. A disturbance recorder which can handle at

least 20 analog channels and at least 60 binary signals and that can record the

last 50 disturbances shall be included. It should be possible to record the sum of

selected analog currents. An event recorder that can handle up to 150 time

tagged events per disturbance and that can record the last 50 disturbances shall

also be included. An accurate fault locator with compensation for load current

and mutual zero sequence impedance for double circuit lines shall be available.

The IED shall be provided with a front mounted human machine interface

(HMI) and a front port for connection of a personal computer. The HMI shall

include LEDs for status indication and at least 15 configurable LEDs for alarm

indication. The IED shall be provided with communication interface for

connection to substation automation system and substation monitoring system.

IEC 61850-8-1 and IEC 60870-5-103 communication protocol shall be

available. The IED shall meet the IEC 61850 standard in every respect and

interoperability with other manufactures IEDs and tools should be verified.It shall be possible to select different mounting alternatives such as rack, flush

or wall mounting.

Depending of the required numbers of I/O modules in the IED shall 1/1 x

19, x 19and x 19 cases are available.

Power supply modules from 24 to 250 DC +/- 20 % shall be available.

GPS time synchronization module with GPS receiver used for timesynchronization shall be available.

A test switch for mounting in connection with the IED should be available.


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Contact Name

Atkins India Pvt. Ltd.10

thFloor, Safina Towers

3 Ali Askar RoadBangalore 560096

Telephone: +91 (80) 4019199Fax: +91 (80) 41475822

5108879 14 01 1000 rev0 transmission protection

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