suitable settings auto reclose

DETERMINING SUITABLE SETTINGS FOR AUTO

RECLOSING SCHEMES OF THE SRI LANKAN

TRANSMISSION SYSTEM

G.R.H.U. Somapriya

08/8321

Degree of Master of Science

Department of Electrical Engineering

University of Moratuwa

Sri Lanka

September 2012

DETERMINING SUITABLE SETTINGS FOR AUTO

RECLOSING SCHEMES OF THE SRI LANKAN

TRANSMISSION SYSTEM

Gama Ralalage Harshana Udayakumara Somapriya

08/8321

Dissertation submitted in partial fulfillment of the requirements for the

Degree Master of Science in Electrical Installations

Supervised by: Dr.K.T.M.Udayanga Hemapala

Department of Electrical Engineering

University of Moratuwa

Sri Lanka

September 2012

i

DECLARATION “I declare that this is my own work and this dissertation does not incorporate without

acknowledgement any material previously submitted for a Degree or Diploma in any

other University or institute of higher learning and to the best of my knowledge and

belief it does not contain any material previously published or written by another

person except where the acknowledgement is made in the text.

Also, I hereby grant to University of Moratuwa the non-exclusive right to reproduce

and distribute my dissertation, in whole or in part in print, electronic or other

medium. I retain the right to use this content in whole or part in future works (such as

articles or books)”.

Signature of the candidate Date:

(G.R.H.U. Somapriya)

The above candidate has carried out research for the Masters Dissertation under my

supervision.

Signature of the supervisor Date:

(Dr. K.T.M. Udayanga Hemapala)

ii

ABSTRACT

The majority of faults in the transmission network can be successfully cleared by the proper use of protective relays to trip the respective circuit breakers and to bring back the system to normalcy using high speed autoreclosing. Thus, autoreclosing can significantly reduce the outage time due to faults and provide a higher level of service continuity to the customer. Furthermore, successful high-speed reclosing on transmission circuits can be a major factor when attempting to maintain system stability during fault clearing. Initial studies revealed that a detailed study of Autoreclosing settings in the transmission network of Ceylon Electricity Board and their performance based on failure analysis has not been carried out since the review of the protection system and settings by Lahmeyer International in 1996. Further there has been a brief analysis by the PB power consultants in their report on the CEB transmission system and organizational arrangements for operation and maintenance in October 1999. Since then there has been a comprehensive expansion of the CEB transmission network. Existing settings were reviewed along with failure incidents recorded during the period of November 2006 to August 2012 in the selected transmission lines. The stability analysis was carried out with the existing settings and prospective settings using the existing CEB power system which is modeled in PSSE software. Based on the simulated results, analysis of failure incidents, review of existing settings and the literature available on the practices followed in determining Auto reclose settings a set of Auto reclose settings for 220kV and 132kV transmission lines were proposed. These new settings and recommendations will improve the AR success rate thereby improving the reliability of the network. It will also minimize the risk of major failures resulted due to the definitive tripping of important transmission lines due to transient faults. Key words: Auto reclosing, Transmission lines, Simulations, Failure analysis.

iii

ACKNOWLEDGEMENT

First, I pay my sincere gratitude to Dr. K.T.M. Udayanga Hemapala who encouraged

and guided me to conduct this investigation and on perpetration of final dissertation.

I extend my sincere gratitude to Prof. J.P. Karunadasa, Head of the Department of

Electrical Engineering and to the staff of the Department of Electrical Engineering

for the support extended during the study period. My mind runs to the golden days

when we studied various subjects of Electrical Engineering under the wonderful

guidance of Prof. Rohan Lucas, Prof. Ranjith Perera, Dr. Narendra De Silva, Dr.

Priyantha Wijethunga and Dr. Thilak Siyambalapitiya among many others.

My special thanks go to Mr. Jayasiri Karunanayake who helped me select this topic

and guided me patiently whenever I approached him for advice.

I would like to express my deep gratitude to Eng. Eranga Kudahewa who gave the

valuable instructions during the simulations and spent a lot of valuable time in

helping me.

I would like to take this opportunity to extend my sincere thanks to Mr.D.D.K.

Karunarathne, Deputy General Manager (TD & E), Mr.T.D.Handagama, Deputy

General Manager (System Control), Mr.N.S.Wettasinghe, Chief Engineer (Protection

Development Section), Mr.D.S.R.Alahakoon, Chief Engineer (System Operations),

Mr. J.Nanthakumar Chief Engineer (Operation Planning), Mr. Nadun Chamikara,

Electrical Engineer (Protection Development Section) and all the Office Staff of

Protection Development Section of Ceylon Electricity Board who gave their co-

operation to conduct my investigation work successfully.

It is a great pleasure to remember the kind co-operation and motivation provided by

the family and the friends and specially my wife Dilhani who helped me to continue

the studies from start to end.

iv

TABLE OF CONTENTS

Declaration of the candidate & Supervisor i

Abstract ii

Acknowledgements iii

Table of Content iv

List of Figures vii

List of Tables viii

List of Abbreviations ix

List of Appendices x

1. Introduction 1

1.1 Background 1

1.2 Identification of the problem 2

1.3 Objective of the Study 2

1.4 Importance of the study 3

1.5 Methodology 3

2. Principles of Autoreclosing 4

2.1 Theory of Autoreclosing 4

2.2 Basis for the analysis of Stability using software models 8

2.3 PSSE Simulation Software & Network Model 8

3. Review of existing settings and failure analysis 10

3.1 Existing Auto Reclosing Settings of 220kV Lines 10

3.1.1 Summary of existing settings 10

3.1.1.1 Single and three phase AR 11

3.1.1.2 Dead Times 12

3.1.1.3 Synchro Check Condition 12

3.1.1.4 Single Shot and Multi Shot AR 13

3.1.2 Analysis of previous failure incidents of 220kV system 13

3.1.2.1 Failure incidents of Biyagama - Kothmale lines 13

3.1.2.2 Failure incidents of Veyangoda - Norochcholai lines 16

3.2 Existing Auto Reclosing Settings of 132kV Lines 19

3.2.1 Review of settings of 132kV system 1 20

3.2.2 Review of settings of 132kV system 2 22

3.2.3 Analysis of previous failure incidents of 132kV system 23

v

4. Stability Analysis 24

4.1 Three phase Autoreclose of 220kV lines 24

4.1.1 Biyagama – Kothmale 220kV lines 24

4.1.1.1 Simulation of 3ph AR for a dead time of 5s 24

4.1.1.2 Simulation of 3ph AR for a dead time of 1.2s 26

4.1.1.3 Simulation of 3ph AR for a dead time of 1s 27

4.1.1.4 Simulation of 3ph AR for a dead time of 750ms 28



4.1.2 Veyangoda – Norochcholai 220kV lines 31


4.2 Single phase Autoreclose of 220kV lines 33

4.2.1 Biyagama – Kothmale 220kV lines 33


4.2.2 Veyangoda – Norochcholai 220kV lines 35


4.3 Autoreclose of 132kV lines 36

4.3.1 AR of Balangoda – New Laxapana with dead time of 300ms 36


4.3.3 AR of Balangoda – New Laxapana with dead time of 1.2s 38


4.4 Effects of Autoreclose on generators 40

4.4.1 Three phase autoreclose 40

4.4.2 Single phase autoreclose 41

5. Conclusion and Recommendations 42

5.1 AR of 220kV Transmission Lines 42

5.2 AR of 132kV Transmission Lines 43

5.3 AR of generators 44

6. Conclusion and Recommendations 47

6.1 Recommended settings for 220kV Transmission Lines 47

6.2 Recommended settings for 132kV Transmission Lines 47

6.3 AR of generators 48

Reference List 49

vi

Appendix A: Failure incidents of Biyagama – Kothmale lines 51

Appendix B: Failure incidents of Veyangoda – Norochcholai lines. 53

Appendix C: AR status of 132kV transmission lines 54

Appendix D: Load Flow Network Diagram 62

vii

LIST OF FIGURES

Page

Figure 2.1 Application of the Equal-Area Criterion for Stability to the Reclosing of a Single-Circuit Tie Between Systems A and B.

6

Figure 2.2 Response of a four machine system during a transient 8

Figure 2.3 Snap shot of Biyagama – Kothmale transmission line modeled in PSSE

9

Figure 3.1 Digital Disturbance Record of Kelanitissa GIS 15

Figure 3.2 Frequency Plot for the major failure on 28th April 2008 at 17.28 hrs 16

Figure 3.3 Digital Disturbance Record for Veyangoda – Norochcholai line 1 19

Figure 3.4 Digital Disturbance Record for Norochcholai - Veyangoda line 1 20

Figure 3.5 Autoreclose scheme of 132kV network 1 21

Figure 3.6 Autoreclose scheme of 132kV network 2 22

Figure 3.7 Unsuccessful AR incident in Polpitiya Seethawaka line 23

Figure 3.8 Successful AR incident in Polpitiya Seethawaka line 23

Figure 4.1 Relative rotor angle vs Time for a dead time of 5s 25

Figure 4.2 Power Angle Curve for Kothmale Generator 26

Figure 4.3 Relative rotor angle vs Time for a dead time of 1.2s 27

Figure 4.4 Relative rotor angle vs Time for a dead time of 1s 28

Figure 4.5 Relative rotor angle vs Time for a dead time of 750ms 29



Figure 4.8 Rotor angle vs Time for a dead time of 750ms (Veyangoda – Noro.) 32

Figure 4.9 Relative rotor angle vs Time for a dead time of 750ms (Vey.– Noro.) 33

Figure 4.10 Rotor angle vs Time for a dead time of 450ms (1 ph. AR Biya.-Kothmale)

34

Figure 4.11 Relative rotor angle vs Time for a dead time of 450ms (1 ph. AR Biya.-Kothmale)

35

Figure 4.12 Relative rotor angle vs Time for a dead time of 450ms (1 ph. AR Vey.-Nor.)

36

Figure 4.13 Relative rotor angle vs Time for a dead time of 300ms (Lax. – Bal.) 37

Figure 4.14 Relative rotor angle vs Time for a dead time of 500ms (Lax. – Bal.) 38

Figure 4.15 Relative rotor angle vs Time for a dead time of 1.2s (Lax. – Bal.) 39

Figure 4.16 Relative rotor angle vs Time for a dead time of 800ms(Pan. – Math) 40

Figure 4.17 Power angle curve of Victoria Generators for 3ph AR of Biyagama Kothmale lines dead time 1.2s

40

Figure 4.18 Power angle curve of Victoria Generators for 1ph AR of Biyagama Kothmale lines dead time 450ms

41

viii

LIST OF TABLES

Page

Table 3.1 Existing 220kV Auto reclose settings 11

Table 3.2 Synchro check conditions 12

Table 3.3 AR settings of Kolonnawa – Athurugiriya and Polpitiya – Seethawaka Lines

21

Table 3.4 Auto reclose settings of Pannipitiya- Panadura – Horana system 22

Table 5.1 Proposed Auto reclose settings for Biyagama – Kothmale and

Veyangoda – Norochcholai 220kV lines

40

Table 6.1 Recommended AR settings for 220kV transmission lines 47

Table 6.2 Recommended AR settings for interconnected 132kV transmission

lines

48

Table 6.3 Recommended AR settings for 132kV transmission lines connecting

two isolated networks

48

ix

LIST OF ABBREVATIONS Abbrevation Description

CEB Ceylon Electricity Board

PSSE Power System Simulator for Engineering

AR Auto Reclosing

KCCP Kelanithissa Combined Cycle Plant

EDG Emergency Diesel Generator

SSR Subsynchronous Resonant Oscillations

HSR High Speed Reclosing

DDR Digital Disturbance Recorder

x

LIST OF APPENDICES Page

Appendix A Failure incidents of Biyagama – Kothmale lines 51

Appendix B Failure incidents of Veyangoda – Norochcholai lines. 53

Appendix C AR status of 132kV transmission lines 54

Appendix D Load Flow Network Diagram 62

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Chapter 1

INTRODUCTION

1.1. Background

Various studies have shown that approximately 90%, of faults on most overhead

transmission lines are transient [1, 2, 3]. A transient fault, such as an insulator

flashover, is a fault which is cleared by the immediate tripping of one or more circuit

breakers to isolate the fault, and which does not recur when the line is re-energized.

Lightning is the most common cause of transient faults, partially resulting from

insulator flashover from the high transient voltages induced by the lightning. Other

possible causes are swinging wires and temporary contact with foreign objects. The

majority of faults can be successfully cleared by the proper use of protective relays to

trip the respective circuit breakers and to bring back the system to normalcy using

high speed AR. This de-energizes the line long enough for the fault source to pass

and the fault arc to de-energize, then automatically recloses the line to restore

service. Thus, AR can significantly reduce the outage time due to faults and provide

a higher level of service continuity to the customer. Furthermore, successful high-

speed reclosing on transmission circuits can be a major factor when attempting to

maintain system stability during fault clearing.

Initial studies revealed that a detailed study of AR settings in the transmission

network of Ceylon Electricity Board(CEB) and their performance based on failure

analysis has not been carried out since the review of the protection system and

settings by Lahmeyer International in 1996. [4] Further there has been a brief

analysis by the PB power consultants in their report on the CEB transmission system

and organizational arrangements for operation and maintenance in October 1999. [5]

Since then there has been a comprehensive expansion of the CEB transmission

network. [6, 7]

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Initially the failure incidents of the Sri Lanka’s transmission network for the period

January 2006 to August 2012 were analyzed. Then the settings employed in high

speed AR schemes this network were studied and whether they are providing the

desired results are being discussed.

Main objective of the research is to propose suitable AR settings for the 132kV and

220kV lines in the Sri Lankan Transmission Network.

1.2 Identification of the problem

With the experience gained through failure analysis at the protection development

section of CEB for over four years period the need for a detailed study of AR settings

was felt. There has not been a comprehensive study, including stability analysis to

determine the AR schemes for the transmission network. There were some major

power system failures which could have been avoided if the AR schemes were

properly set. Further rapid development of the CEB power system and the

technological advancement of protection relays make some of existing settings

obsolete.

1.3 Objective of the study

The objective of the study is to determine suitable settings for AR for the Sri Lankan

transmission system after carrying out stability analysis using the existing CEB

power system which is modeled in PSSE software. By simulation of AR of some

selected lines, maximum time available for opening and reclosing the system without

loss of synchronism would be determined. Using analysis of previous failure

incidents and studying existing literature other factors that require proposing AR

settings would be determined.

This study will present a set of AR settings for both 220kV and 132kV systems

which will improve the AR success rate thereby improving the reliability of the

network. It will also minimize the risk of major failures resulted due to the definitive

tripping of important transmission lines due to transient faults.

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1.4 Importance of the study

A comprehensive study on the AR settings for the 132kV and 220kV lines in the Sri

Lankan Transmission Network has not been conducted in recent times. With the

rapid development of the transmission network there has been a need to revise the

existing settings to match with the current system. The outcome of this project will

help to improve the stability and reliability of the national grid.

1.5 Methodology

Existing settings were reviewed along with failure incidents recorded during the

period of November 2006 to August 2012 in the selected transmission lines. The

stability analysis was carried out with the existing settings and prospective settings

using the existing CEB power system which is modeled in PSSE software. Based on

the simulated results, analysis of failure incidents, review of existing settings and the

literature available on the practices followed in determining AR settings, a set of AR

settings for 220kV and 132kV transmission lines were proposed.

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Chapter 2

PRINCIPLES OF AUTO RECLOSING

2.1 Theory of Auto Reclosing

As discussed in the Chapter 1.1, the majority of faults in the transmission lines can be

successfully cleared by the proper use of protective relays to trip the respective

circuit breakers and to bring back the system to normalcy using high speed AR.

Power system stability is understood as the ability to regain an equilibrium state after

being subjected to a physical disturbance. [8] A primary concern in the application of

AR, especially on transmission lines is the maintenance of system stability and

synchronism. This is normally done through the application of high-speed tripping

and AR. The problems involved with maintaining system stability when AR during a

fault on the line depend on the characteristics of the system - whether it is loosely

connected, for example, with two power systems connected by a single tie line, or,

conversely, highly interconnected, in which case maintaining synchronism during

AR is much easier.

High-speed AR is used on transmission and subtransmission systems for improving

stability by clearance of transient faults. The intent of AR on transmission and

subtransmission systems, other than the maintenance of stability, is to bring back the

system to its normal configuration, with the minimum use of manpower whilst

limiting the outage time of the line to a minimum. System restoration becomes

increasingly important when applied to transmission lines that interconnect

generation systems and are critical for reliable power exchange between such

systems. Individual utility policy and system requirements dictate the complexity and

variety of automatic reclosing schemes in service today.[1]

Factors to consider when using high-speed AR include:[2]

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1 The maximum time available for opening and reclosing the system without loss

of synchronism (maximum dead time). This time is a function of the system

configuration and the transmitted power.

2 The time required for de-ionization of the arc path so that the arc will not restrike

when the breaker is reclosed. This time can be estimated by the use of a formula

developed from empirical data gathered from laboratory tests and field

experience.

3 The protection relay characteristics

4 The circuit breaker characteristics and limitations.

5 Choice of reclose reset time

6 Number of reclose attempts

The transient following the perturbation on the system is oscillatory and dampens to

a new quiescent condition if the system is stable. The oscillations are reflected as

power fluctuations over the power line and can be represented graphically using the

equal area criterion and the power-angle curve [9].

The power-angle curve of a synchronous machine relates the power output of the

machine to the angle of its rotor. For a two-machine system this can be represented

as:

Where:

P= the power transmitted between the machines during the transient condition

VS= the voltage at the sending end

VR= the voltage at the receiving end

δ= the angle by which VS leads VR

The maximum power occurs when the angle between the two machines is 90°s and

the minimum power occurs when the angle is 0° or 180°. Figure 2.1 shows a power-

angle curve for a simple two-machine system with a single transmission line

connecting the two sources, A and B. The curve for normal conditions is the one with

the greatest height and with a maximum of:

sinX

PRS

VV

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Figure 2.1 – Application of the Equal-Area Criterion for Stability to the Reclosing of

a Single-Circuit Tie between Systems A and B [3]

During the fault (2LG) the power-angle curve is reduced as shown, and during the

opening of the breakers, the amplitude of the curve is zero. The height of the

horizontal line labeled ‘Input’, Pi, represents the electrical and mechanical power

transmitted prior to the fault. The initial angular separation of machines A and B is

δ0, the clearing angle is δ 1, the reclosing angle is δ 2, and the angle of maximum

swing without loss of synchronism is δ 3. The equal area criterion requires that for

stability, area 2 must exceed area 1. Without reclosure, synchronism would be lost

regardless of the amount of power transmitted. Hence, the stability limit without

reclosure is zero. With rapid enough clearing and reclosure, however, the stability

limit can be made to approach the amplitude of the normal power-angle curve.

To determine whether the system in Figure 2.1 is stable, we must calculate the areas

1 and 2. If area 2 is greater than area 1, then the system is stable. If area 2 equals area

1, then the input power of 0.9 per unit, Pi, is the stability limit. Any higher input

power would cause area 2 to increase and area 1 to decrease, thus causing instability

(assuming they are equal prior to increasing the input power). If area 1 is greater than

pu 83.1

6.0

0.11.1P

BA

M

X

VV

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area 2, then the system is unstable. Area 2 is slightly less than area 1, thus the system

is unstable. In order to ensure stability for the 2LG fault, area 1 must be decreased

and/or area 2 must be increased. This can be done by reducing the input power, Pi, or

by clearing the fault faster (i.e., reclosing faster).

If single-phase AR is used on a transmission line, for example, a single-line to-

ground fault, tripping only the faulted phase will allow an interchange of

synchronizing power that would otherwise be unavailable when all three phases are

open. Hence by single-phase tripping/AR the stability limit of the line can be raised

above the limit obtainable with three-pole tripping and reclosing at the same speed.

Alternatively, the same stability limit can be achieved with slower AR.

Power angle curves give the power transfer as a function of phase angle difference

between sets of machines, and it is necessary to relate the phase angle difference to

time. This can be done by solving the swing equation for the particular sets of

machines.

The swing equation is

Pa = M d2δ/ dt2

where

Pa = accelerating power, difference between mechanical input and electrical output

M = Inertia constant

δ = displacement of machine rotor from a reference axis rotating at normal

synchronous speed

t = time

Solution of the swing equation gives phase angle δ as a function of time and can be

plotted against the swing curve. Using the swing curves for the particular machines,

and the power angle curves for the particular type of faults, it will be possible to

work out the maximum fault clearance time and auto-reclose dead time necessary to

maintain a given power transfer level.

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2.2 Basis for the analysis of Stability using software models

Using the swing curves for the particular machines, and the power angle curves for

the particular type of faults, it will be possible to work out the maximum fault

clearance time and auto-reclose dead time necessary to maintain a given power

transfer level.

If the system is stable, all interconnected synchronous machines should remain in

synchronism (i.e., operating in parallel and at the same speed) as shown in figure 2.2

(a). System shown in Figure 2.2 (b) is out of synchronism.

Figure 2.2 – Response of a four machine system during a transient [3]

2.3 PSSE Simulation Software & Network Model

PSCAD and PSSE are the power system simulation software that was considered to

carry out the above studies. The requirement was to model the actual existing

network of the CEB and simulate the selected scenarios. But the available license of

the PSCAD software was of limited capability which prevented the modeling of

complete transmission network. Then PSSE was considered which is a tool used by

the CEB.

PSS®E is an integrated, interactive program for simulating, analyzing, and

optimizing power system performance. It is capable of simulation of Power Flow,

Optimal Power Flow, Balanced or Unbalanced Fault Analysis, Dynamic Simulation,

Extended Term Dynamic Simulation, Open Access and Pricing, Transfer Limit

Analysis and Network Reduction. [10]

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Figure 2.3 – Snap shot of Biyagama – Kothmale transmission line modeled in

PSSE

Actual system of CEB which is modeled by the transmission planning branch and

system control centre was used to carryout the study. Complete diagram of the

network model used for the simulation of different auto reclosing scenarios is

presented in annexure D. Snap shot of the simulation is shown in the figure 2.3.

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Chapter 3

REVIEW OF EXISTING SETTINGS AND FAILURE ANALYSIS

3.1. Existing Auto Reclosing Settings of 220kV Lines

All the existing 220kV transmission lines in CEB network employ single phase and

three phase auto reclosing. Their settings are not uniform. Two most important lines

in the network has been selected for in-depth analysis of existing settings. They are

Biyagama – Kotmale line and Norochcholai – Veyangoda line. The existing settings

of all 220kV lines were studied.

Biyagama – Kothmale double circuit transmission line (70.5km) is the backbone in

CEB transmission network which connect Mahaweli power generation plants to the

load centre in Colombo. As discussed in chapter 2, the stability analysis of

transmission lines during AR comes in to picture when two networks independent

generation are connected through that line. e.g. Biyagama – Kothamale line where

Biyagama side is also connected to the thermal power complexes.

Veyangoda – Norochcholai double circuit transmission line (115 km) was selected

because of its critical importance during dry seasons when the Mahaweli generation

is low. Additionally these lines are frequently subjected to transient faults (Insulator

flashovers) due to the high salinity of the coastal environment. But it is observed that

the line is definitively tripped even for transient faults and resultant effect of one of

these incidents have lead to scheduled load shedding in August 2012.

3.1.1. Summary of existing settings

Settings of 220kV transmission lines have been determined during the

commissioning period of each transmission line and are sometimes being altered

after failure analysis. Table 3.1 presents a summary of existing settings of Biyagama

– Kotmale and Norochcholai – Veyangoda transmission lines.

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Table 3.1 – Existing 220kV AR settings

No Substation & Line

Portion

Single phase Auto reclosing 3 phase Auto Reclosing

Syn. check

condition for AR

Dead

Time

Syn. check

condition for AR

Dead

Time

1 Norochchole GIS –

Veyangoda Line 1 & 2

No Synchro.

Check 800 ms LB/LL 750 ms

2 Veyangoda GSS –

Norochchole Line 1 & 2

No Synchro.

Check 800 ms LB/LL or LB/DL 550 ms

3 Biyagama – Kothmale

Line

No Synchro.

Check 450ms LB/DL 1.0S

4 Kothmale - Biyagama

Line

No Synchro.

Check 450ms LB/LL or LB/DL 1.2S

3.1.1.1.Single and three phase AR

Statistics show that above 80% of faults on overhead lines are transient, with more

than 90% of these are single phase to earth faults. The most common causes of

transient faults are over voltages induced by lightning, which result in flashover of

insulator. Other possible causes are swinging wires and temporary contact with

foreign objects. For such faults, single pole AR provides a means of improving

transient stability and reliability. Furthermore, in single phase AR only the faulted

phase is tripped and 58% of transmission capacity is still retained via the two healthy

phases [11].

Single phase AR is employed in 220 kV lines only. They are not used in 132 kV

lines. Single phase auto reclosing is used without synchronization. Hence lower dead

times are employed in comparison to three phase AR.[6]

The stability limit of the line can be raised above the limit obtainable with three-pole

tripping and reclosing at the same speed. Alternatively, the same stability limit can be

achieved with slower AR. Single pole switching also has the advantage of reducing

mechanical shock to generators compared to three phase reclosing. [4]

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Three phase AR is used in all transformers and medium voltage feeders. i.e. 33 kV

3.1.1.2.Dead Times

Dead time is the time between opening of the CB due to a fault and the first AR

attempt. It is common practice to employ a dead time based on the time needed for

the transient fault to extinguish and to sustain system stability and reliability.

However employing a fixed prescribed dead time can pose problems. In the case of

an arcing fault, for example, a fault restrike due to insufficient time for the fault path

to fully de-ionise can threaten system stability and reliability. On the other hand,

unsuccessful reclosing during a permanent fault may aggravate the potential damage

to the system and equipment [12]. For some EHV lines, especially near generating

plants, the classical automatic reclosing of breakers cannot be used and therefore

adaptive reclosing schemes have been introduced over the past decades [13,14,15].

3.1.1.3.Synchro Check Conditions

Re-closing of the breaker is only done when the two sides are in Synchronism, when

both sides are in live condition. Synchronism check relays generally check for phase

angle, voltage and frequency difference when employed in AR schemes. Table 3.2

gives existing synchro check conditions in CEB network.

Table 3.2 – Synchro check conditions

Acceptable voltage difference ∆V = +_ 10%

Acceptable phase angle difference ∆d = +_ 20 Deg

Acceptable frequency difference ∆f = +_0.1 Hz

Live Bus LB 80 % Ub (Ub – Base Voltage)

Live Line LL 80 % Ub

Dead Bus DB 30 % Ub

Dead Line DL 30 % Ub

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3.1.1.4.Single Shot and Multi Shot AR

Only single shot AR is used in transmission lines (220 kV/ 132 kV) to avoid any

damage to equipment due to persistent faults. Further most transient faults are cleared

within the first AR cycle making multi shot AR less beneficial.

3.1.2. Analysis of previous failure incidents of 220kV system

Success rate or suitability of existing AR settings can be determined by analyzing

previous failure incidents. All incidents involving 220kV transmission lines for the

past 5 years have been studied. Detailed analysis was carried out on few incidents

involving two critical lines in the network, which are Biyagama –Kothmale and

Norochcholai – Veyangoda lines.

3.1.2.1.Failure incidents of Biyagama –Kothmale 220kV transmission lines

Biyagama - Kothmale 220kV transmission line is the backbone connecting Mahaweli

complex to the load centre in Colombo. Hence the tripping of these lines could lead

to a major failure in CEB transmission network. When analyzing previous records of

such incidents it was evident that proper auto reclosing of the line could have

prevented some total failures of the national grid.

When investigating the incidents recorded from 2006-2012, it is revealed that most of

the failures has resulted in definitive trips when the dead time was 5 seconds. AR

success rate has improved after the revision of dead time to 1.2s in 2009.

Please refer Appendix A for a detailed list of failure incidents involving Biyagama –

Kothmale Transmission lines.

There were incidents involving these lines that lead to blackouts / Major failures

which could have been prevented if AR settings had been properly set:

A. Total System Failure on 15th November 2006 at 19.33 hrs.

B. Major System Failure on 28th April 2008 at 17.28 hrs.

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Detailed analysis Major System Failure on 28th April 2008 at 17.28 hrs.

On 28th April 2008 at 17.28 hrs there was a double circuit fault in Kotmale -

Biyagama 220 kV lines and the system lost most of the Mahawali hydro generators

due to tripping of these lines. This has resulted in a major failure in the system. On

this instance Kothmale- New Anuradapura 220 kV line was switched off for

maintenance work. Prior to tripping of Kothmale - Biyagama lines the load on these

lines was approximately 900 A (300 MW) and the total system generation was 1108

MW.

The failure has been initiated by double circuit fault in Biyagama – Kothmale 220 kV

lines involving Yellow - Blue phases and ground. The distance relays installed in

both ends have seen a zone 1 multi-phase fault and tripped respective circuit breakers

and initiated the auto-reclosers. After the auto-recloser dead time (5 sec) Biyagama

end breakers have been re-closed successfully but breakers at Kothmale end have

been failed to re-close. At t = 5 sec Biyagama end frequency has fallen to 47.4 Hz

and hence the check synchronizing relays at Kothmale end had blocked auto-

reclosing.

Then the power flown from Kothmale to Biyagama has been re-routed to the system

via Rantambe 220kV/132kV system transformer. The tripping of Kothmale-

Biyagama lines has caused a power swing through Badulla-Laxapana lines.

Apparently due to this the distance relays installed at Badulla – Laxapana lines have

tripped the line by operation of distance protection zone 1. (At t =0.6 sec.) By this

time the system has been divided into two sections viz. Mahawali power stations

with Badulla and Ampara GSS have been in one system and rest of the grid

substations as another system.

At t = 0.6 sec. the main system was having a power deficiency of about 270 MW and

the system frequency started decreasing. Please see figure 3.2 for frequency vs. time

curve. According to the frequency plot, the system frequency has started to increase

at about t = 4.1 sec due to automatic load shedding and governor action of individual

machines. But the recovery has not been fast enough to avoid tripping of thermal

machines. Viz. Kelanithissa Barge, KCCP ST and GT.

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At t = 5.15 sec Kelanithissa Barge mounted power plant (60 MW) and at t = 5.5 sec

Kelanithissa combine cycle steam power plant (57 MW) tripped on under frequency.

Further at t = 6.5 sec Kelanithissa combine cycle gas turbine tripped (104 MW) and

started collapsing the system frequency.

Under Frequency Trip Settings:-

Kelanithissa Barge power plant : 47.5 Hz, 0.0 sec.

Kelanithissa combine cycle steam power plant : 48.0 Hz, 3.0 sec.

Kelanithissa combine cycle gas turbine power plant : 47.5 Hz, 3.2 sec.

Figure 3.1 - Digital Disturbance record of Kelanitissa GIS

Kothmale, Victoria, Randenigala, Rantambe power stations and Badulla, Ampara

GSS were in this system. Initially this system had excess power of about 300 MW.

Later this system got stabilized and fed the loads at Rantambe, Badulla and Ampara

GSS.

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43

44

45

46

47

48

49

50

51

-0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5

Time (s)

Fre

q (

Hz)

60

80

100

120

140

160

180

200

220

240

Vo

ltag

e (k

V)

Freq

Volt

Tripping of Badulla-Laxapana lines (300 MW)

Tripping of Biyagama-Kothmale lines

Tripping of KCCP-GT (104 MW)

Tripping of KCCP-ST (57 MW)

Tripping of Kelanithissa Barge

(60 MW)

43

44

45

46

47

48

49

50

51

-0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5

Time (s)

Fre

q (

Hz)

60

80

100

120

140

160

180

200

220

240

Vo

ltag

e (k

V)

Freq

Volt

Tripping of Badulla-Laxapana lines (300 MW)

Tripping of Biyagama-Kothmale lines

Tripping of KCCP-GT (104 MW)

Tripping of KCCP-ST (57 MW)

Tripping of Kelanithissa Barge

(60 MW)

The existing auto-reclosing scheme in Biyagama – Kothmale lines were having dead

time of 5 seconds. The need was felt to review the dead time and if possible to reduce

the same.

The results of these incidents clearly demonstrate the significance of implementing

suitable AR settings to improve power system reliability. Consequent to this incident

the AR settings were revised to the values shown in Table 3.1.

Figure 3.2 - Frequency Plot for the major failure on 28th April 2008 at 17.28 hrs

3.1.2.2.Failure incidents of Veyangoda – Norochcholai 220kV transmission lines

Veyangoda – Norochcholai double circuit 115km transmission line was

commissioned in 2011 to connect Lakvijaya coal power plant to the national grid.

Since then there have been several failure incidents involving the line. Availability of

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these two lines is critical to match the demand especially during the drought season

where hydropower generation is at minimum level.

When investigating the incidents recorded since 2011 it is apparent that most of the

times AR has been successful at Veyangoda end. But since the AR switch is in off

position at Norochcholai end definitive trip of the line has resulted in each incident

recorded.

Please refer Appendix B for the detailed list of failure incidents involving Veyangoda

– Norochcholai Transmission lines.

AR switch was at off position at Norochcholai end and hence the line has tripped

definitively even for transient faults which have lead to serious crisis situations in the

national grid as discussed below.

One of the most significant incidents was the tripping of the Lakvijaya power plant

as a result of a flashover in the transmission line and subsequent events that lead to

scheduled power cuts in the island.

Tripping on 08 August 2012 5.57 am

On 08 August 2012 5.57 am, Unit at the Lakvijaya power plant tripped after a total

disconnection from the grid due to one 220k V line circuit taken out for maintenance

and the other one lost due to flash over. During the turbine-generator rundown

bearings hindered damage as was verified during an unsuccessful restart attempt on

12 August-9pm. As a result the bearings 3&4 needed replacement after a cool-down

period of the turbine of nine days. On 26 August, 10.30pm the Unit was back on the

grid on low load. However two unresolved problems hindered the further loading of

the Unit namely undue noise emitted from the main transformer and debris fliers in

the main cooling water lines to the condenser out of order.

On 07 June 2011 a very similar incident took place with most conditions leading up

to the Unit trip (2 line circuits lost, generator breaker remained closed) and the

outcome (failure to runback to house load, EDG failed to supply power .lube oil

starvation, turbine bearing damage. etc) being almost identical.

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Failures contributing to the Incident

The generator over-frequency protection is set to operate at 52.5 HZ 0.5s and trips

the turbine (but not the generator circuit breaker) Concerns about this setting had

been highlighted during reviews of the settings prior to commissioning and again

following the incident in June 2011. The action of this protection has the adverse

consequences.

I. There is no chance of a trip to Island or House mode since the turbine is

tripped.

II. Without tripping the generator circuit breaker, the turbine governor system

operation by first stage of OPC governing at 51.5 Hz ( when the steam values

are shut.) occurs later than would be the case for a load rejection type

situation. The resulting over speed peak was 4.1 Hz. close to the second stage

of governor protection over speed trip at 55 Hz. It is possible that this

additional speed rise could have contributed to damage to an already

imperfect bearing (following damage in June 2011)

III. The generator remained connected to the system for min 48s. During this

period the voltage and frequency steadily declined until the generator CBX

190 was tripped by the excitation protection. Any attempt to close by DAR or

manually during this period would have been disastrous – hence the

recommendation last year to leave DAR switched off until the matter is

resolved.

IV. The declining frequency on the auxiliary system is matched by an over-

fluxing control within the excitation system so that voltage is reduced in

proportion to frequency. Operation of pumps and fans etc. will be impaired

until such time as the EDG starts to supply only essential drives.

Following immediately on from the incident, the overhead line did not auto-reclose

and attempts by the operators to switch back the affected line and later the line under

maintenance were unsuccessful until supply was restored through the Veyangoda 2

line almost 1 hour after the Veyangoda 1 line had tripped.

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The auto-reclose system is switched out at Puttalam. This has been deliberate

pending resolution of issues arising from the incident of June 2011. The line auto-

reclosed from the Veyangoda end and manual operation would be needed to switch

in the Puttalam end.

Figure 3.3 - Digital Disturbance Record for Veyangoda – Norochcholai line 1

The fault was multi-phase type so that irrespective of whether the auto-reclose had

been switched in, in this case it would have been unsuccessful due to loss of

synchronism between the generator (if it had kept running) and the system.

3.2. Existing Auto Reclosing Settings of 132kV Lines

With the growth of the 220kV transmission network of CEB, effects of AR of

individual 132kV transmission lines on the overall stability of the network is largely

insignificant. But with proper AR of 132kV lines the reliability of the transmission

network can be improved and automatic load shedding can be minimized. Hence it is

possible to employ relatively longer dead times for AR of 132kV transmission lines.

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Figure 3.4 - Digital Disturbance Record for Norochcholai - Veyangoda line 1

3.2.1. Review of settings of 132kV system 1

AR scheme that involve Athurugiriya and Thulhiriya lines were observed to have a

very high AR success rate. Hence the scheme with synchrocheck conditions are

presented in figure 3.5.

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Figure 3.5 – Autoreclose scheme of 132kV network 1

Table 3.3 – AR settings of Kolonnawa – Athurugiriya & Polpitiya - Seethawaka lines


Portion

Syn. check

condition for AR

Dead

Time

Reclaim

Time/Inhibit

Time

1 Kolonnawa - Athurugiriya

Lines

LB/LL or LB/DL 0.8 Sec 180 Sec

2 Athurugiriya – Kolonnawa

Lines LB/LL 1.1 Sec 180 Sec

3 Polpitiya - Seethawaka

Lines

LB/DL 0.8 Sec 180 Sec

4 Seethawaka – Polpitiya

Lines LB/LL 1.1 Sec 180 Sec

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3.2.2. Review of settings of 132kV system 2

AR settings of Pannipitiya- Panadura – Horana 132kV system is quite similar to

that of system 1.

Figure 3.6 – Autoreclose scheme of 132kV network 2

Table 3.4 – AR settings of Pannipitiya- Panadura – Horana 132kV system


Portion

Syn. check

condition for AR

Dead

Time

Reclaim

Time/Inhibit Time

1 Pannipitiya- Matugama

Line

LB/DL 800 ms 300 Sec

2 Matugama- Pannipitiya

Line

LB/LL 1.1 Sec 300 Sec

3 Panadura- Pannipitiya

Matugama Line

DB/LL 1.5 Sec 300 Sec

Some lines like Pannala-Katunayake, Aniyakanda- Kelaniya has AR dead times

as low as 300ms.

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3.2.3. Analysis of previous failure incidents of 132kV system

Figure 3.7 Unsuccessful AR incident in Polpitiya Seethawaka line

Digital Disturbance records obtained from the BEN 5000 DDR installed at Polpitiya

Powerstation were quite helpful in assessing the suitability of the existing settings

(Table 3.5) implemented at Polpitiya Seethawska lines. Figure 3.7 shows an incident

involving a permanent fault while figure 3.8 provide a clear testimony to the

successful AR for a disturbance due to a transient fault.

Figure 3.8 Successful AR incident in Polpitiya Seethawaka line

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Chapter 4

STABILITY ANALYSIS

4.1. Three phase Autoreclose of 220kV lines

4.1.1. Biyagama – Kothmale 220kV lines

It is understood that the most critical line that affect system stability are Biyagama –

Kothmale 220kV double circuit transmission line. So the autoreclose of these lines

was simulated using PSSE under several power system conditions. Most critical of

these is when hydro generation of the Mahaweli complex is at the maximum which is

connected to the main load centre in Colombo. Thermal maximum condition was

also considered.

The simulated dead times were 5s, 1.2s, 1s, 750ms, 500ms and 300ms. 300ms is the

lowest possible time that can be assigned considering the fault clearance times. 5s

was the setting used before 2008. 1.2s is the currently applied 3ph AR time setting.

Apart from these values 500ms, 750ms and 1000ms were considered to obtain a

better understanding of the response of the power system to auto reclosing at

different dead times.

4.1.1.1. Simulation of AR for a 3ph double circuit fault at Biyagama – Kothmale

line with a dead time of 5s

Dead time of 5 seconds was the setting that was available during the two total

failures mentioned above and it was subsequently changed in 2008.

Algorithm adopted for simulation of 3ph double circuit fault:

1. Run the instance of the model for 2 seconds.

(Mahaweli generation 166MW, Thermal 718MW)

2. Create 3ph double circuit fault & run for 50ms

3. Trip both lines

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4. Clear the fault

5. Run the instance of the model for 5 seconds. (Dead time=5s)

6. Reclose the line

7. Run the model for another 15 seconds

The outputs of these simulations can be obtained in several graphs. Figure 4.1 shows

the graph between relative power angles versus time. As we discussed above for the

stability to be maintained relative angles of these lines should be in parallel. When a

dead time of 5s is selected the system stability is disturbed. Rotor angles of Victoria

and Kothmale machines are in parallel while the Kelanithissa CCP and Puttalama

Coal plant are separated. Hence the stability of the system cannot be maintained with

a dead time of 5s.

Figure 4.1 - Relative rotor angle vs Time for a dead time of 5s

Power angle curve of the Kothmale machine at this instance is shown in figure 4.2.

Reference: Rotor angle of generator at Kothmale PS

Victoria

Kelanithissa Combined Cycle

Puttalama Coal

Angle Difference

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Figure 4.2 - Power Angle Curve for Kothmale Generator

4.1.1.2.Simulation of 3ph double circuit fault at Biyagama – Kothmale line with

a dead time of 1.2s

Dead Time of 1.2s is the setting that is currently used for three phase auto reclosing

in these lines. It was simulated following the steps similar to that were followed in

previous cases.





3. Trip both lines

4. Clear the fault

5. Run the instance of the model for 1200 miliseconds. (Dead

time=1200ms)

6. Reclose the line


Rotor Angle

Power Generated

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Simulation result for AR with a dead time of 1.2s in Biyagama Kothamle 220kV line

for a three phase double circuit fault is shown in figure 4.3.

Figure 4.3 - Relative rotor angle vs Time for a dead time of 1.2s


a dead time of 1s

Simulation for dead time of 1s was carried out using the same algorithm that was

described under 4.1.1.1 The output plot was obtained as a plot of Rotor angle

realative to that of Kothmale against time.





3. Trip both lines

4. Clear the fault

5. Run the instance of the model for 1 second. (Dead time= 1 s)

6. Reclose the line


Victoria

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Simulation result for AR with a dead time of 1s in Biyagama Kothamle 220kV line


Figure 4.4 - Relative rotor angle vs Time for a dead time of 1s


a dead time of 750ms

Simulation for dead time of 750ms was carried out using the same algorithm that was

described under 4.1.1.1 The output plot was obtained as a plot of Rotor angle relative

to that of Kothmale against time.





3. Trip both lines

4. Clear the fault


New Laxapana PS


West Coast Power Plant

Lakvijaya Coal Power Plant

Angle Difference

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5. Run the instance of the model for 0.75 second. (Dead time= 0.75 s)

6. Reclose the line


Simulation result for AR with a dead time of 0.75s in Biyagama Kothamle 220kV

line for a three phase double circuit fault is shown in figure 4.5.

Figure 4.5 - Relative rotor angle vs Time for a dead time of 750ms



Simulation for dead time of 500ms was carried out using the same algorithm that was

described under 4.1.1.1 The output plot was obtained as a plot of Rotor angle

realative to that of Kothmale against time.





3. Trip both lines

4. Clear the fault


New Laxapana PS




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5. Run the instance of the model for 500 milliseconds. (Dead time= 500 ms)

6. Reclose the line


Simulation result for AR with a dead time of 0.5s in Biyagama Kothamle 220kV line





Dead Time of 300ms is the minimum setting that could be set after considering fault

clearance times and breaker operation times.





3. Trip both lines

4. Clear the fault

5. Run the instance of the model for 300 miliseconds. (Dead time=300ms)


New Laxapana PS




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6. Reclose the line


Simulation result for AR with a dead time of 300ms in Biyagama Kothamle 220kV

line for a three phase double circuit fault is shown in figure 4.7.


When a 300ms of dead time is selected the system disturbance is cleared within a

short period. Plot in figure 4.7 shows that they are in parallel and in synchronism.

4.1.2. Veyangoda – Norochcholai 220kV lines

4.1.2.1. Simulation of 3ph double circuit fault at Veyangoda – Norochcholai line

with a dead time of 750ms

Dead Time of 750ms is the setting that is currently used for three phase auto

reclosing in these lines.



Angle Difference

Puttalama Coal


Victoria


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3. Trip both lines

4. Clear the fault

5. Run the instance of the model for 750 miliseconds. (Dead time=750ms)

6. Reclose the line


Simulation result for AR with a dead time of 750ms in Veyangoda Norochcholai

220kV line for a three phase double circuit fault is shown in figure 4.8 and figure

4.9.

Figure 4.8 – Rotor angle vs Time for a dead time of 750ms

As shown in figure 4.8 rotor angle of Puttalama PS and Victoria PS are not in

parallel indicating that they are not in synchronism.

Victoria

Puttalama Coal

Angle

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Figure 4.9 – Relative Rotor angle vs Time for a dead time of 750ms

4.2. Single phase Autoreclose of 220kV lines

Single phase AR is used when the faults involve only one phase of the transmission

line i.e.L-G faults. This will help to clear the fault with minimum disturbance to the

system. Automatic reclosing of the breaker is done without synchronizing the two

ends. Only 220kV breakers are capable of single pole tripping in our network. Hence

single phase auto reclosing is used only for 220kV transmission lines.

4.2.1. Biyagama – Kothmale 220kV lines

4.2.1.1. Single phase AR of Biyagama - Kothmale with a dead time of 450 ms

The existing dead time setting for single phase AR in Biyagama Kothmale line is

450ms.

Algorithm adopted for simulation of single phase to ground fault:

Puttalama Coal


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1. Run the instance of the model for 2 seconds. Consider one circuit of

double circuit lines are out for maintenance.


2. Create single phase fault & run for 50ms

3. Trip the single phase involved.

4. Clear the fault


time=450ms)

6. Reclose the line


The results are shown in figure 4.10 and figure 4.11.

Figure 4.10– Rotor angle vs Time for a dead time of 450ms

Puttalama Coal

Victoria

Kothmale

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Figure 4.11 - Relative Rotor angle vs Time for a dead time of 450ms

Both 450ms & 750ms can be increased without compromising stability and

reliability. It is advisable to have longer dead times near generating stations to

limit thermal/ mechanical stresses on the generators.

4.2.2. Veyangoda – Norochcholai 220kV lines

4.2.2.1. Single phase AR of Veyangoda Norochchole with a dead time of 800 ms

Single phase auto reclosing at Veyangoda Norochcholai lines is quite important

since they are subject to transient L-G faults due to the saline environment in the

transmission line route. Effects of single phase AR were simulated to compare

the output with the three phase AR results. Simulation steps were similar to that

was followed in single phase AR of Biyagama – Kothmale lines. Simulation

resultas are shown in figure 4.12.

Puttalama Coal


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4.3. Autoreclose of 132kV lines

Single shot three phase auto reclosing is used in almost all the 132kV

transmission lines in the CEB network. For the simulation of stability two lines

New Laxapana – Balangoda and Pannipitiya – Mathugama which were identified

to have been associated with several failure incidents in the past few years have

been selected.

4.3.1. 132kV three phase AR Balangoda – New Laxapana with dead time of

300ms

The existing dead time setting for three phase AR in New Laxapana – Balangoda

line is 300ms. Hence dead time of 300ms, 500ms and 1200ms were simulated.

Algorithm adopted for simulation of three phase double circuit fault:

1. Run the instance of the model for 2 seconds. (Mahaweli

generation 166MW, Thermal 718MW)


Puttalama Coal


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3. Trip both lines

4. Clear the fault


time=300ms)

6. Reclose the line



Simulation result for AR with a dead time of 300ms in New Laxapana – Balangoda

132kV line for a three phase double circuit fault is shown in figure 4.13.


500ms

The minimum dead time for 132kV transmission lines is 286.5 ms. This is further

explained in chapter 5.2. To allow more time for fault clearance a dead time of

500ms can be set and same has been simulated following similar algorithm to that of

4.3.1 changing only the dead time. Resulting plot of relative rotor angle vs time is

shown in Figure 4.14

Samanalaweva

Reference: Rotor angle of generator at New Laxapana

ACE Embilipitiya

KCCP

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Simulation result for AR with a dead time of 500ms in New Laxapana – Balangoda

132kV line for a three phase double circuit fault is shown in figure 4.14.


1200ms

For highly interconnected transmission lines longer dead times can be set. It was

interesting to simulate for a longer dead time for Balangoda - New Laxapana lines

although these lines connect two islands. Hence a dead time of 1200ms was

simulated following similar algorithm to that of 4.3.1 changing only the dead time.

Resulting plot of relative rotor angle vs time is shown in Figure 4.15

Samanalaweva


ACE Embilipitiya

KCCP

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Figure 4.15- Relative Rotor angle vs Time for a dead time of 1.2s

4.3.4. 132kV three phase AR Pannipitiya – Mathugama with a dead time of

800ms

The existing dead time setting for three phase AR in Pannipitiya Mathugama line is

800ms.

Algorithm adopted for simulation of three phase double circuit fault:

1. Run the instance of the model for 2 seconds. (Mahaweli

generation 166MW, Thermal 718MW)


3. Trip both lines

4. Clear the fault


time=800ms)

6. Reclose the line


Samanalaweva


ACE Embilipitiya

KCCP

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Figure 4.16- Relative Rotor angle vs Time for a dead time of 800ms

Simulation result for AR with existing dead time of 800ms in Pannipitiya

Mathugama 132kV line for a three phase double circuit fault is shown in figure 4.16.

4.4. Effects of Autoreclose on generators

4.4.1. Three phase autoreclose

Figure 4.17 – Power angle curve of Victoria Generators for 3ph AR of Biyagama

Kothmale lines dead time 1.2s

Mechanical Power (pu)

Rotor angle

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As shown in figure 4.17 the power angle curve of Victoria generators for AR of

Biyagama Kothmale lines with a dead time of 1.2s, the curve returns to its original

position indicating that the stability of the generators are maintained under these

conditions.

4.4.2. Single phase autoreclose

Figure 4.18 – Power angle curve of Victoria Generators for 1ph AR of Biyagama

Kothmale lines dead time 450ms

Figure 4.18 shows the power angle curve of Victoria generators for single AR of

Biyagama Kothmale lines with a dead time of 450ms, the curve returns to its original

position indicating that the stability of the generators are maintained under these

conditions

13

Power Angle Curve Victoria GeneratorMechanical Power (pu)

Rotor angle

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Chapter 5

RESULTS AND ANALYSIS

5.1. AR of 220kV Transmission Lines

Analysis of existing settings, failure incidents and PSSE simulation results provide

the basis for determining the most suitable settings for the auto reclosing settings of

CEB’s transmission network.

The failure analysis using digital disturbance records reveal that most of the transient

faults are cleared within 100ms. The breaker operation times and relay operation

times also need to be considered.

As per Protective Relaying Theory & Application by ABB Minimum Dead Time T is

given by:

T = 10.5 + kV / 34.5 cycles

Hence for 220kV transmission lines the minimum dead time shall be:

T= 10.5 + 220/34.5 = 16.87 cycles = 337.5 ms

Table 5.1 – Proposed AR settings for Biyagama – Kothmale and Veyangoda –

Norochcholai 220kV lines


Portion

Single phase Auto reclosing 3 phase Auto Reclosing

Syn. check

condition for AR

Dead

Time

Syn. check

condition for AR

Dead

Time

1 Norochchole GIS –

Veyangoda Line 1 & 2

No Synchro.

check 450 ms LB/LL 750 ms

2 Veyangoda GSS –

Norochchole Line 1 & 2

No Synchro.

Check 450 ms LB/LL or LB/DL 550 ms

3 Biyagama – Kothmale

Line

No Synchro.

check 450 ms LB/LL 750 ms

4 Kothmale - Biyagama

Line

No Synchro.

check 450 ms LB/LL or LB/DL 550 ms

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According to the PSSE simulations it is advisable to use a dead time as small as

possible for the Biyagama – Kothmale lines since it directly affects the overall

system stability of CEB transmission network. But it should be at least 337.5 ms on

technical basis. Considering the old condition of available switchgear, an additional

tolerance for the initial tripping of the breaker should be allowed. Hence it is safe to

apply 550ms for the A/R dead time for the first reclosing end for multi phase faults.

For the other end it is safe to apply 200ms delay to allow the energization of the line.

Synchrocheck condition shall be LB/LL or LB/DL for the end which will first reclose

while the other end should be closed after checking for the LB/LL condition only.

For single phase AR it is recommended to provide a dead time of 450ms based on

existing disturbance records and available literature. This is much safer than three

phase AR and has no effect on system stability as per the PSSE simulations. Here the

automatic reclosing of the breaker will be performed without synchrocheck.

5.2. AR of 132kV Transmission Lines

Auto reclosing of 132kV lines has a limited effect on the overall system stability.

Hence it is possible to employ longer dead times to enable higher AR success rate.

Analysis of existing settings reveal that there a uniform standard has not been

followed in determining the AR settings of 132kV lines. Some lines like Pannala-

Katunayake, Aniyakanda- Kelaniya has AR dead times as low as 300ms.

But as for the equation 5.1 the minimum dead time for 132kV transmission lines

shall be:

T= 10.5 + 132/34.5 = 14.32 cycles = 286.5 ms

Considering the time delays involved in the initial tripping operation much longer

dead time shall be adopted for AR of 132kV lines.

After considering all these factors including the analysis of past incidents and AR

success rates it is recommended to implement AR settings that are available in

Pannipitiya- Panadura – Horana lines (Table 3.6) as a standard throughout the

network.

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Analysis of existing schemes revealed that relays capable of AR are not available in

some old transmission lines. (Refer Annexure 3) Hence it is recommended to install

AR schemes for these lines to improve reliability. AR of Balangoda – New laxapana

lines would have prevented three major failures which affected the southern region in

this year alone.

5.3. AR of Generator feeders

On single-tie circuits with dispersed generation, reclosing on the circuit must be

delayed long enough for the dispersed generation to be isolated from the utility. [16,

17] If this does not happen, the generator may be damaged due to the utility source

closing into the generator out of synchronism. As an additional safety factor, where

there is customer generation, voltage supervision is often applied to the AR scheme.

In this case, AR is delayed until a dead line is sensed (also known as live line

blocking, or LLB), thus preventing reclosing into the dispersed generation.

Alternatively, if high-speed tripping (transfer trip, pilot wire, etc.) is used to trip the

generation, high-speed reclosing may be considered. If the dispersed generator has

the capacity to maintain the connected load, it may be used to do so in the event that

the utility tie is lost. In this case, the dispersed generation needs to have the ability

for dead line closing. In addition, before the utility tie is reestablished, this generation

must be isolated from the utility to prevent the utility from damaging the generator

when re-energizing. This can be done either locally or remotely. The generation can

also be tied back to the utility system using synchronism check. If the generation

capacity is insufficient to supply the connected load, it should be removed from the

system upon a trip of the utility supply and prior to the utility reclosing.

Effects of AR on Generator Shafts

Recent studies have raised concerns with reclosing breakers near generation and the

possibility of exceeding stress limits in turbine generator shafts. As early as 1944, in

a paper on single pole switching, the problem of mechanical shock to generator

shafts during fault clearing and reclosing was discussed. The authors concluded that

the calculation of stresses “may dictate single pole switching, regardless of transient

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power limits. Because of the uncertainties of reclosing near generating stations,

application practices vary widely and many include one or more of the following:

[16, 17]

1. Delayed reclosing for all faults (e.g., 10 seconds or more to allow decay of

oscillations)

2. Sequential reclosing, remote end first.

3. Selective HSR (e.g., Single pole operation or other type of relaying

designed to avoid reclosing on multiphase faults)

4. No automatic reclosing at all.

Delayed reclosing for all faults:

One recommended alternative to HSR is to allow enough dead time (delay reclosing)

for the torsional shaft oscillations produced by the initial fault to decay [16]. The

damping of the subsynchronous resonant oscillations (SSR) is the damping due to the

twisting of the turbine-generator interconnecting shaft and the damping associated

with the oscillations of the turbine blades due to interaction with the steam.

Studies indicate that damping of the SSR oscillations is a function of load and is

dominated by the steam-turbine blade interaction [9]. One study shows that damping

time constants range from 8 to 30 seconds, depending on the level of excitation (due

to switching, HSR, etc.). Reclosing delays of 10 seconds have been recommended in

some studies. Studies have also shown that models can be used to determine the

torques that result on the turbine-generator due to various disturbances in the power

system. This, by itself, doesnot determine the amount of damage these torques cause

to the turbine-generator. A suggested fatigue model used for the evaluation of this

damage is very complex and uses assumptions based on both empirical and statistical

methods. This fact must be recognized when interpreting any results using this

model. It is suggested that fatigue cannot be directly correlated to simple measures,

such as the shaft's peak torque following a disturbance, but that it is a cumulative

effect related to the overall nature of the torque transient.

Further study in the area of torsional fatigue is suggested to improve techniques for

predicting accumulating damage.

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Sequential reclosing:

Reclosing the remote end of a line with generation will result in reduced torsional

stress on the generator, provided the remote end is electrically removed enough from

the generator.

Various studies have concluded that significant shaft damage is possible when high-

speed reclosing into a close-in, three-phase fault. However, at least one study shows

no significant damage for any fault where HSR is successful or for any line-ground

fault even where HSR is not successful [16].

Past practices of eliminating HSR near generator sites are being challenged by recent

studies. It has been suggested that HSR not be eliminated at these sites unless it can

be shown, for a specific situation, that the risk of shaft damage is significant. High-

speed reclosing near generator sites has the potential to enhance system reliability

and maintain generation that would otherwise be lost during system disturbances, and

these recent studies indicates possible review of existing reclosing policies. [18, 19,

20]

In CEB system the three phases AR is always performed after synchrocheck. Hence

it is safe to turn on three phase AR near generator stations.

These studies confirm that it is safer to switch on single phase AR in 220kV lines

connecting generator stations like Norochcholai and Kerawalapitiya power plants.

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Chapter 6

CONCLUSION & RECOMMENDATIONS

6.1. Recommended settings for 220kV Transmission Lines

Based on the analysis of existing settings and PSSE simulations recommended dead

times for three phase AR of 220kV lines can be summarized in table 6.1.

Table 6.1 – Recommended AR settings for 220kV transmission lines

Line Synchro Check Dead Time

Substation at one end LB/LL 750ms

Substation at the other end LB/LL & LB/DL 550ms

The substation nearer to generating station shall employ the longer dead time.

A dead time of 450ms is adequate to clear any transient fault which is proven by

analyzing DDR records. Hence for single phase AR of 220kV transmission line a

Dead Time of 450ms is recommended. Single phase AR does not require synchro

check.

6.2. Recommended settings for 132kV Transmission Lines

Analysis of existing settings and PSSE simulations reveal that the existing settings

for most of the 132kV lines are acceptable. But it is recommended to bring the

settings at different stations under a uniform scheme depending on the nature of the

line.

Recommended dead times for highly interconnected 132kV lines are given in table

6.2

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Table 6.2 – Recommended AR settings for interconnected 132kV transmission lines


Substation at one end LB/LL 800ms

Substation at the other end LB/LL & LB/DL 1100ms

Recommended dead times for tie lines connecting two systems eg. Balangoda - New

Laxapana to maintain stability are shown in table 6.3.

Table 6.3 – Recommended AR settings for 132kV transmission lines connecting two

isolated networks


Substation at one end LB/LL & LB/DL 300ms

Substation at the other end LB/LL 500ms

Further it is recommended to switch on AR on all transmission lines after revising

the AR settings accordingly.

6.3. AR of Generator feeders

It is recommended to switch on single phase AR near generating stations when

connected through 220kV transmission lines.

It is advisable to have longer dead times near generating stations to limit thermal/

mechanical stresses on the generators and then switch on AR to improve reliability.

In such situations the remote end should reclose first.

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References

[1] IEEE Power Systems Relaying Committee; Automatic Reclosing of

Transmission Lines; IEEE Transactions, Vol. PAS-103, Feb. 1984, no. 2,

pages 234 - 245

[2] Protection Relay Application Guide; GEC Measurements, 1975

[3] Kimbark, Edward Wilson, ScD; Power System Stability; John Wiley & Sons,

Inc.,N.Y., London

[4] Lahmeyer International, “Review of protection system and settings of CEB

transmission network”, 1996

[5] PB Power, “Report on the CEB transmission system and organizational

arrangements for operation and maintenance”, Volume 4, October 1999

[6] Ceylon Electricity Board, Transmission Plan, 1999

[7] Ceylon Electricity Board, “Long Term Transmission Development Plan

2011-2020”, July 2011.

[8] Jan Machowski, Janusz W. Bialek, James R. Bumby; Power System

Dynamics Stability and Control ; Second Edition, John Wiley & Sons Ltd.,

2008

[9] Basler Protective Relay Technical Papers; “Automatic Reclosing -

Transmission Line Applications and Considerations”, Available:

http://www.basler.com, accessed on January 2009

[10] Siemens Energy, Inc., “PSS®E 32.0 Program Operation Manual”, Revised

June 2009

[11] Ahn S. P., Kim C. H., Aggarwal R.K. and Johns A. T., “An alternative

approach to adaptive single pole auto-reclosing in high voltage transmission

systems based on variable dead time control,” IEEE Transaction on Power

Delivery, Vol. 16, No. 4, pp. 676-686, October 2001.

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[12] Bo Z. Q., Aggarwal R. K. and Johns A. T., “A novel technique to distinguish

between transient and permanent fault based on detection of current

transients,” Proceeding of 4th International Conference on Advances in

Power System Control and Management, APSCOM-97, Hong Kong, pp. 217-

220, November 1997.

[13] Bowler C. E. J., Brown P. G. and Walker D. N., “Evaluation of the effect of

power circuit breaker reclosing practices on turbine-generator shaft,” IEEE

Transaction on Power Apparatus System, Vol. PAS-99, pp. 1764-1779, 1980.

[14] Walter A. Elmore; “ Protective Relaying Theory and Applications”, ABB

Power T&D Company Inc., Relay Division, Coral Springs, Florida, Chapter

15, 1994

[15] The Electricity Training Association, “Power System Protection”, The

Institution of Electrical Engineers, Volume 3, 1997

[16] M.C. Jackson, et al.; Turbine Generator Shaft Torque and Fatigue: Part I –

Simulation Methods and Fatigue Analysis; IEEE Transactions, Vol. PAS-98,

1979, pages 2299-2307, Part I

[17] M.C. Jackson, et al.; Turbine Generator Shaft Torque and Fatigue: Part II -

Impact of System Disturbances and High-speed Reclosing; IEEE

Transactions, Vol. PAS-98, 1979, pages 2308-2313, Part II

[18] P. Kundor: Power System Stability and Control: New York: McGraw-Hill,

1994.

[19] Vibration Signatures R. Oliquino, Jr., S. Islam, SMIEEE and H. Eren,.;

Effects of Types of Faults on Generator; School of Electrical and Computer

Engineering, Curtin University of Technology, Western Australia

[20] IEEE Power Systems Relaying Committee Working Group; "Single Phase

Tripping and Auto Reclosing of Transmission Lines,"; IEEE Transactions on

Power Delivery, vol. 7, 1992.

Appendix A failure incidents of Biyagama ‐ Kothmale 220 kV Transmission lines

Date Tripped Station Equipment No.Volt. Level (kV)

Relay operated & indicationsObservation (Actual fault /Mal operation /Any other Remarks)

2010.03.11 13.08 Kothmale Biyagama 1 220 REL521 - VTSZ , VTRIP , REL511 - VTSZ , VTSP, TP

2010.03.11 13.08 Biyagama Kothmale 1 220 DEF.2010.08.07 17.03 Biyagama Kotmale 2 132 RAAM (AR Relay) - Relay operated2010.08.07 17.03 Kotmale Biyagama 2 132 REL 521 - Auto Reclosed2010.09.30 18.12 Biyagama Kotmale 1 220 THR - Zone 1, R Phase, EF RAZFE - RN, U2010.09.30 18.12 Biyagama Kotmale 2 220 RHIDF2H - OC R Phase RAZFE - RN, U

2010.09.30 18.12 Kotmale Biyagama 1 220 REL 521 (M1) - IMP-PSL1, IMP-PSN, IMP-ZM3, CR<Z, EF-STEF, AR INPROGR

2010.09.30 18.12 Kotmale Biyagama 2 220REL 521 (M1) - IMP-PSL1, IMP-PSN, IMP-ZM3, CR<Z, EF-STEF, AR INPROGR, IMP-TRC, TRIP-

GTRIP, IMP-ZM2, TRIP- SPTRIP2010.11.28 14.39 Biyagama Kotmale 1 220 RAZFE - RN, U THR - EF-R

2010.11.28 14.39 Biyagama Kotmale 2 220 RAZFE - RN, TN, U 7SA 522 - PICK UP L3, PICK UP E, CARRIER SEND

2010.11.28 14.39 Kotmale Biyagama 1 220

REL 521 (M1) - IMP-PSL1, IMP-PSN, IMP-ZM1, IMP-ZM2, IMP-ZM3, CSZ, TR-Z1, TR-SOTF, AR INPROGR, TRIP-GTRIP, TRIP- SPTRIP, TRIP-

TPTRIP REL 316 - Start R, Start E, Delay 1, AR in progress, Com send


REL 521 (M1) - IMP-PSL1, IMP-PSN, IMP-ZM1, IMP-ZM2, IMP-ZM3, CSZ, TR-Z1, TR-SOTF, AR INPROGR, TRIP-GTRIP, TRIP- SPTRIP, CRZ< REL 316 - Start R, Start B, Start E, Delay Z1, AR

in progress

2010.11.28 14.42 Biyagama Kotmale 2 220 RAZFE - TN


REL 521 (M1) - IMP-PSL3, IMP-PSN, IMP-ZM1, IMP-ZM2, IMP-ZM3, TRC, CSZ, TR-Z1, Hװ - TROCL3, AR INPROGR, TRIP-GTRIP, TRIP-

SPTRIP, CRZ< REL 316 - Start B, Start E, Delay Z1, AR in progress, Com send

Actual fault.

Biyagama - Kotmale line 2 was not auto reclosed because fault cleared at Biyagama

end by Backup protection. M1 & M2 relays at Biyagama end failed to clear the fault.

Actual fault.

Annex1 Biya_Koth Trippings 1

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Date Time Station Equipment No kV Relay operated & indications Observation

28-Nov-10 14.42 Biyagama Kotmale 2 220 RAZFE - TN Major System failure, A separate report prepaired

28-Apr-08 17.28 Biyagama Kothmale 2 220THR - Zone 1 , Phase Y , B , EF - Y , B Total Failure.( A separate report prepared )

28-Nov-10 14.39 Biyagama Kotmale 1 220 RAZFE - RN, U THR - EF-R Major System failure, A separate report prepaired

28-Nov-10 14.39 Biyagama Kotmale 2 220

RAZFE - RN, TN, U 7SA 522 - PICK UP L3, PICK UP E, CARRIER SEND Major System failure, A separate report prepaired

18-Apr-08 19.55 Biyagama Kothmale 1 220 RAZFE - U , TN Actual fault.

11-Feb-09 14.36 Biyagama Kothmale 2 220 Inter trip received. A separate report submitted.

11-Feb-09 14.36 Biyagama Kothmale 1 220 Inter trip received. A separate report submitted.

01-Jun-08 13.45 Biyagama Kothmale 2 220

THR - Zone 1 , Earth - B. RAZFE - U , TN. , Pole Discordance operated. Further analysis required.

27-May-08 13.24 Biyagama Kothmale 2 220THR - Zone 1 , 2 , Phase - yb , Earth -y Actual fault.

07-Aug-10 17.03 Biyagama Kotmale 2 132RAAM (AR Relay) - Relay operated Actual fault.

11-Mar-10 13.08 Biyagama Kothmale 1 220 DEF. Actual fault.

06-Dec-09 16.34 Biyagama Kotmale 1 220 RAZFE - U , 3Ø Actual fault.

06-Dec-09 16.34 Biyagama Kotmale 2 220 RAZFE - RN , 2Ø Actual fault.

30-Sep-10 18.12 Biyagama Kotmale 1 220THR - Zone 1, R Phase, EF RAZFE - RN, U

Biyagama - Kotmale line 2 was not auto reclosed because fault cleared at Biyagama end by Backup protection. M1 & M2 relays at Biyagama end failed to clear the fault.

30-Sep-10 18.12 Biyagama Kotmale 2 220RHIDF2H - OC R Phase RAZFE - RN, U

Biyagama - Kotmale line 2 was not auto reclosed because fault cleared at Biyagama end by Backup protection. M1 & M2 relays at Biyagama end failed to clear the fault.

24-May-11 23.48 Biyagama Kotmale 1 220RAZFE - SN, U THR - EF-Y, Auto Reclosed Actual fault

28-Apr-08 17.28 Biyagama Kothmale 1 220RAZFE - U , 2Ø , THR - Phase Y , B , Earth Y , B . Total Failure.

20-Feb-11 17.51 Biyagama Kotmale 2 220

RAZFE - TN, U 7SA 522 - Trip phase 1, Z1, Z1 B, Carrier send, Carrier receive

27-May-11 3.40 Biyagama Kotmale 2 220

RAZFE - TN, U 7SA 522 - Trip phase L1, Z1, CR, CS Auto Reclosed Actual fault

27-May-11 3.40 Biyagama Kotmale 1 132RAZFE - U THR - EF-B, Auto Reclosed Actual fault

20-Feb-11 17.51 Biyagama Kotmale 1 220 RAZFE - UN, U THR - EF-B

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Appendix B Tripping of Veyangoda ‐ Norochcholai 220 kV Transmission lines

Date Tripped Station Equipment No.Volt. Level (kV)

Relay operated & indicationsObservation (Actual fault /Mal operation /Any other Remarks)

16.07.2012 0.30 Norochchole Veyangoda 1 220(M1) NARI RCS 931 AM - OP –Z-DPFC-ABC-8ms, OP-Diff-ABC-13ms, OP-Z1 –ABC-20ms, Fault location ABC-3.6 km SAC PSL602GCM - - Indications not recorded.

16.07.2012 0.30 Veyangoda Norochchole 1 220

Interposing relay set - Trip Coil 1, Phase A trip, CB reclose, AR operate NARI RCS 931- AM - Trip A,Reclose OP –Diff OP-AR Fault location 00.30-107.6 km SAC PSL602GCM - Z-S-Z-mo2 tr, pilot fault.

04.08.2012 22.09 Norochchole Veyangoda 2 220NARI RCS 931- AM - Indications not recorded. SAC PSL602GCM - Dis.&-z-s.pro.st, Distance = 40m


Interposing relay set - Trip Coil 1 - PhaseC trip, CB reclose, AR operate NARI RCS 931- AM - Trip C, Reclose SAC PSL602GCM - Trip, Reclose

05.08.2012 1.59 Norochchole Veyangoda 2 220NARI RCS 931- AM - Indications not recorded. SAC PSL602GCM - Dis.&-z-s.pro.st, Distance = 70m


Interposing relay set - Trip Coil 1 - Phase C trip, CB reclose, AR operate NARI RCS 931- AM - Trip C, Reclose SAC PSL602GCM - Trip, Reclose

08.08.2012 5.57 Norochchole Veyangoda 1 220NARI RCS 931 AM - OP–ZDPFC, OP-Diff, OP-Z1, Fault location 11.4 km SAC PSL602GCM - - Indications not recorded.


Interposing relay set - Trip Coil 1 - Phase C trip, CB reclose, AR operate NARI RCS 931- AM - Trip C, Fault location = 70.5 km, Reclose SAC PSL602GCM - Trip, Reclose

Line was auto-reclosed from Veyangoda end. Actual Fault



Line was auto-reclosed from Veyangoda end. Actual Fault. Fault currents in Veyangoda R

phase = 1073 A. Y Phase = 534 A. B Phase = 3060 A Fault currents in Norochchole R phase = 1101 A. B Phase = 384 A. Y Phase = 4131

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Appendix C AR Status of 132kV Transmission lines

StationLine Status Remarks

Habarana Habarana - Old Anuradapura 02 OFF due to pneumatic CB

Habarana Habarana - Old Anuradapura 01 ON

Habarana Habarana - Ukuwela 02 OFF due to pneumatic CB

Habarana Habarana - Ukuwela 01 ON

Habarana Habarana - Valachchena OFF due to pneumatic CB

New Anuradapura New Anuradapura - Kothmale 02 ON

New AnuradapuraNew Anuradapura - Old Anuradapura 02 OFF Reason Unknown

New AnuradapuraNew Anuradapura - Old Anuradapura 01 OFF Reason Unknown

New Anuradapura New Anuradapura - Trinkomale 01 OFF Reason Unknown

New Anuradapura New Anuradapura - Trinkomale 02 OFF Reason Unknown

New Anuradapura New Anuradapura - Vaunia 01 ON

New Anuradapura New Anuradapura - Vaunia 02 ON

Norechchole Norechchole-Veyangoda 01 OFF Reason Unknown

Norechchole Norechchole-Veyangoda 02 OFF Reason Unknown

Old Anuradapura Old Anuradapura - Habarana 01 ON

Old Anuradapura Old Anuradapura - Habarana 02 ON

Old AnuradapuraOld Anuradapura - New Anuradapura 02 ON

Old AnuradapuraOld Anuradapura - New Anuradapura 01 ON

Old Anuradapura Old Anuradapura - Puttalam 02 ON

Old Anuradapura Old Anuradapura - Puttalam 01 ON

Pannala Pannala - Katunayaka ON

Pannala Pannala - Puttalam ON

Puttalam Puttalam - Chilaw ON

Puttalam Puttalam - Pannala ON

Puttalam Puttalam - Old Anuradapura 02 ON

Puttalam Puttalam - Old Anuradapura 01 ON

Trinkomale Trinkomale - New Anuradapura 02 - Not Available

Trinkomale Trinkomale - New Anuradapura 01 - Not Available

Ukuwela Ukuwela - Bowatanna - Not Available

Ukuwela Ukuwela- Habarana 01 - Not Available

Ukuwela Ukuwela- Habarana 02 - Not Available

Ukuwela Ukuwela- Kiribathkubura 02 - Not Available

Ukuwela Ukuwela- Kiribathkubura 01 - Not Available

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Valachchane Valachchane-Habarana - Not Available

Valuniya Vavuniya-New Anuradhapura 01 - Not Available

Valuniya Vavuniya-New Anuradhapura 02 - Not Available

Athurugiriya Athurugiriya - Polpitiya 02 ON

Athurugiriya Athurugiriya - Polpitiya 01 ON

Athurugiriya Athurugiriya-Kolonnawa 01 ON

Athurugiriya Athurugiriya-Kolonnawa 02 ON

Athurugiriya Athurugiriya - Oruwala 01 ON

Athurugiriya Athurugiriya - Oruwala 02 ON

Aniyakanda Aniyakanda-Kotugoda ON

Aniyakanda Aniyakanda-Keleniya ON

Barge Barge - Kelanitissa Not Available

Biyagama Biyagama - Kelanitissa 01 ON

Biyagama Biyagama - Kelanitissa 02 ON

Biyagama Biyagama - Kothmale 01 ON

Biyagama Biyagama - Kothmale 02 ON

Biyagama Biyagama - Pannipitiya 01 OFF

Biyagama Biyagama - Pannipitiya 02 OFF

Biyagama Biyagama - Sapugaskanda 01 ON

Biyagama Biyagama - Sapugaskanda 02 ON

Biyagama Biyagama-Kotugoda 01 ON

Biyagama Biyagama-Kotugoda 02 ON

Biyagama Biyagama - Sapugaskanda PS 01 OFF

Biyagama Biyagama - Sapugaskanda PS 02 OFF

Bolawatta Bolawatta Incoming 01 ON

Bolawatta Bolawatta Incoming 01 ON

Dehiwala Dehiwala-Htown OFF

Dehiwala Dehiwala-pannipitiya OFF

Heladhanvi Heladhanavi - Puttalam 01 Not Available

Heladhanvi Heladhanavi - Puttalam 02 Not Available

Htown Htown-Dehiwala Not Available

Htown Htown-Maradana Not Available

Horana Horana-Pannipitiya ON

Horana Horana-Matugama 01 ON

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Katunayaka Katunayaka-Kotugoda 01 ON

Katunayaka Katunayaka-Kotugoda 02 ON

Katunayaka Katunayaka-Chilaw ON

Katunayaka Katunayaka-Pannala ON

Kelanitissa Kelanitissa - Barge Not Available

Kelanitissa Kelanitissa - Biyagama 01 ON

Kelanitissa Kelanitissa - Biyagama 02 ON

Kelanitissa Kelanitissa - Kolonnawa 02 ON

Kelanitissa Kelanitissa - Kolonnawa 01 ON

Kelanitissa Kelanitissa - Sub F Not Available

Kelanitissa Kelanitissa - Sub C Not Available

Kelaniya Kelaniya - Aniyakanda ON

Kelaniya Kelaniya - Kotugoda 01 ON

Kelaniya Kelaniya -Kolonnawa 01 ON

Kelaniya Kelaniya -Kolonnawa 02 ON

Kelaniya Kelaniya-Sapugaskanda 02 ON

Kelaniya Kelaniya-Sapugaskanda 01 ON

Kelaniya Kelaniya-KHD 01 ON

Kelaniya Kelaniya-KHD 02 ON

KHD KHD - Kelaniya 01 Not available

KHD KHD - Kelaniya 02 Not available

Kolonnawa Kolonnawa - Athurugiriya 02 ON

Kolonnawa Kolonnawa - Athurugiriya 01 ON

Kerawalapitiya GS Kerawalapitiya GS-Kerawala PS 01 Not available

Kerawalapitiya GS Kerawalapitiya GS-Kerawala PS 02 Not available

Kerawalapitiya GS Kerawalapitiya GS-Kotugoda01 OFF

Kerawalapitiya GS Kerawalapitiya GS-Kotugoda02 OFF

Kerawalapitiya PS Kerawalapitiya GS-Kerawala PS 01 Not available

Kerawalapitiya PS Kerawalapitiya GS-Kerawala PS 02 Not available

Kolonnawa Kolonnawa - Kelanitissa 02 ON

Kolonnawa Kolonnawa - Kelanitissa 01 ON

Kolonnawa Kolonnawa - Kelaniya 01 ON

Kolonnawa Kolonnawa - Kelaniya 02 ON

Kolonnawa Kolonnawa - Kosgama 04 ON

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Kolonnawa Kolonnawa - Pannipitiya 01 OFF

Kolonnawa Kolonnawa - Pannipitiya 01 OFF

Kolonnawa Kolonnawa - Seethawaka 03 ON

Kolonnawa Kolonnawa - Sub E Not available

Kolonnawa Kolonnawa - Sub C Not available

Kolonnawa Kolonnawa - Maradana Not available

Kosgama Kosgama - Polpitiya 04 ON

Kosgama Kosgama- Kolonnawa 04 ON

Kotugoda Kotugoda -Aniyakanda ON

Kotugoda Kotugoda - Kelaniya 01 ON

Kotugoda Kotugoda - Katunayaka 02 ON

Kotugoda Kotugoda - Katunayaka 01 ON

Kotugoda Kotugoda - Biyagama 02 ON

Kotugoda Kotugoda - Biyagama 01 ON

Kotugoda Kotugoda - Veyangoda 02 Intergration pos.

Kotugoda Kotugoda - Veyangoda 01 Intergration pos.

Kotugoda Kerawalapitiya GS-Kotugoda01 OFF

Kotugoda Kerawalapitiya GS-Kotugoda02 OFF

Madampe Madampe -Puttalam ON

Madampe Madampe -Katunayaka ON

Maradana Maradana-Htown Not available

Maradana Maradana-kolonnawa Not available

Oruwala Oruwala Incoming 02 Not available

Oruwala Oruwala Incoming 01 Not available

Panadura Paanipitiya / Mathugama OFF

Panadura Paanipitiya / Horana OFF

Pannipitiya Pannipitiya - Biyagama 01 ON

Pannipitiya Pannipitiya - Biyagama 02 ON

Pannipitiya Pannipitiya - Horana 01 ON

Pannipitiya Pannipitiya - Kolonnawa 01 ON

Pannipitiya Pannipitiya - Kolonnawa 02 ON

Pannipitiya Pannipitiya - Matugama 02 ON

Pannipitiya Pannipitiya - Rathmalana 01 Not available

Pannipitiya Pannipitiya - Rathmalana 02 Not available

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Pannipitiya Pannipitiya - Dehiwala OFF

Rathmalana Rathmalana - Pannipitiya 01 Not available

Rathmalana Rathmalana - Pannipitiya 02 Not available

Sapugaskanda G/S Sapugaskanda -Kelaniya 01 OFF

Sapugaskanda G/S Sapugaskanda -Kelaniya 02 OFF

Sapugaskanda G/S Sapugaskanda -Biyagama 01 OFF

Sapugaskanda G/S Sapugaskanda -Biyagama 02 OFF

Sapugaskanda P/S Sapugaskanda P/S - Biyagama 01 OFF

Sapugaskanda P/S Sapugaskanda P/S - Biyagama 02 OFF

Seethawaka Seethawaka-Kolonnawa ON

Seethawaka Seethawaka-Polpitiya ON

Sub E Sub E - Kolonnawa Not available

Sub E Sub E - Sub F Not available

Sub F Sub F - Kelanitissa Not available

Sub F Sub F - Sub E Not available

Sub C Sub C - Kelanitissa Not available

Sub C Sub C - Kolonnawa Not available

Sri'Japura Sri'Japura Incoming 01 ON

Sri'Japura Sri'Japura Incoming 02 ON

Veyangoda Veyangoda - Kotugoda 01 ON

Veyangoda Veyangoda - Kotugoda 02 ON

Veyangoda Veyangoda - Norecchole 01 ON

Veyangoda Veyangoda - Norechchole 02 ON

Balangoda Balangoda - New Laxapana 01 ON

Balangoda Balangoda - New Laxapana 02 ON

Balangoda Balangoda - Rathnapura 01 ON

Balangoda Balangoda - Rathnapura 02 ON

Balangoda Balangoda - Samanalawewa 01 ON

Balangoda Balangoda - Samanalawewa 02 ON

Balangoda Balangoda -Galle ON

Balangoda Balangoda -Deniyaya ON

Deniyaya Deniyaya-Balangoda ON

Deniyaya Deniyaya-Galle ON

Embilipitiya Embilipitiya - ACE Line 1 - Not Available

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Embilipitiya Embilipitiya - ACE Line 2 - Not Available

Embilipitiya Embilipitiya - Hambantota 01 ON

Embilipitiya Embilipitiya - Hambantota 02 ON

Embilipitiya Embilipitiya - Matara ON

Embilipitiya Embilipitiya - Beliaththa ON

Embilipitiya Embilipitiya - Samanalawewa 01 - Not Available

Embilipitiya Embilipitiya - Samanalawewa 02 - Not Available

kukule Kukule-Mathugama 01 ON

kukule Kukule-Mathugama 02 ON

Galle Galle - Deniyaya - Not Available

Galle Galle - Balangoda - Not Available

Hambantota Hambantota - Embilipitiya 01 - No CB

Hambantota Hambantota - Embilipitiya 02 - No CB

Matara Matara - Embilipitiya ON

Matara Matara - Beliaththa ON

Matugama Matugama - Horana ON

Matugama Matugama - Pannipitiya ON

Matugama Kukule-Mathugama 01 ON

Matugama Kukule-Mathugama 02 ON

Matugama Mathugama-Ambalangoada 01 ON

Matugama Mathugama-Ambalangoada 02 ON

Ambalangoda Ambalangoada-Mathugama 01 ON

Ambalangoda Ambalangoada-Mathugama 02 ON

Rathnapura Rathnapura - Balangoda 01 ON

Rathnapura Rathnapura - Balangoda 02 ON

Samanalawewa Samanalawewa - Balangoda 01 ON

Samanalawewa Samanalawewa - Balangoda 02 ON

Samanalawewa Samanalawewa - Embilipitiya 02 ON

Samanalawewa Samanalawewa - Embilipitiya 01 ON

ACE Emb ACE-Emb - Embilipitiya 01 - Not Available

ACE Emb ACE-Emb - Embilipitiya 02 - Not Available

Beliaththa Beliaththa-Matara ON

Beliaththa Beliaththa-Embilipitiya ON

Ampara Ampara - Badulla 01 ON

Harshe

Typewritten Text

59


Badulla Badulla - Rantambe 01 ON

Badulla Badulla - Rantambe 02 - Not Available

Badulla Badulla - Old Lax. 02 ON

Badulla Badulla - Old Lax. 01 ON

Badulla Badulla-Ampara 01 - Not Available

Bowatanna Bowatanna -Ukuwela - Not Available

Canyon Canyon - New laxapana . ON

Inginiyagala Inginiyagala incoming 01

Kiribathkubura Kiribathkubura - Kurunagala 01 ON

Kiribathkubura Kiribathkubura - Kurunagala 02 OFF Reason Unknown

Kiribathkubura Kiribathkubura - Ukuwela 01 OFF Reason Unknown

Kiribathkubura Kiribathkubura - Ukuwela 02 ON

Kiribathkubura Kiribathkubura - Polpitiya 01 OFF Reason Unknown

Kiribathkubura Kiribathkubura - Polpitiya 02 OFF Reason Unknown

Kothmale Kothmale - Biyagama 01 ON

Kothmale Kothmale - Biyagama 02 ON

Kothmale Kothmale - New Anuradapura 02 ON

Kothmale Kothmale - Victoria 01 ON

Kothmale Kothmale - Victoria 02 ON

Kurunagala Kurunagala - Kiribathkubura 01 OFF

Kurunagala Kurunagala - Kiribathkubura 02 OFF

New Laxapana New Laxapana - Balangoda 01 OFF

New Laxapana New Laxapana - Balangoda 02 OFF

New Laxapana New Laxapana - Canyon.

-

New Laxapana New Laxapana - Old Laxapana 01

-

New Laxapana New Laxapana - Old Laxapana 02

-

New Laxapana New laxapana - Polpitiya 01 OFF

New Laxapana New laxapana - Polpitiya 02 OFF

Nuwaraeliya Nuwaraeliya Incoming 02 ON

Nuwaraeliya Nuwaraeliya Incoming 01 ON

Old Laxapana Old Laxapana - New Laxapana 01 ON

Old Laxapana Old Laxapana - New Laxapana 02 ON

Old Laxapana Old Laxapana - Polpitiya 01 ON

Old Laxapana Old Laxapana - Polpitiya 02 ON

Harshe

Typewritten Text

Harshe

Typewritten Text

60


Old Laxapana Old Laxapana - WPS 01 ON

Old Laxapana Old Laxapana - WPS 02 ON

Old Laxapana Old Laxapana -Badulla 01 ON

Old Laxapana Old Laxapana -Badulla 02 ON

Polpitiya Polpitiya - Athurugiriya 02 ON

Polpitiya Polpitiya - Athurugiriya 01 ON

Polpitiya Polpitiya - Kiribathkubura 01 ON

Polpitiya Polpitiya - Kiribathkubura 02 ON

Polpitiya Polpitiya - Kosgama ON

Polpitiya Polpitiya - New Laxapana 01 ON

Polpitiya Polpitiya - New Laxapana 02 ON

Polpitiya Polpitiya - Old Laxapana 01 ON

Polpitiya Polpitiya - Old Laxapana 02 ON

Polpitiya Polpitiya - Seethawaka ON

Randenigala Randenigala - Rantambe - Not Available

Randenigala Randenigala - Victoria - Not Available

Rantambe Rantambe - Randenigala ON

Rantambe Rantambe -Badulla 01 ON

Rantambe Rantambe -Badulla 02 ON

Thulhiriya Thulhiriya Incoming 01 ON

Thulhiriya Thulhiriya Incoming 02 ON

Victoria Victoria - Kothmale 02 OFF Reason Unknown

Victoria Victoria - Kothmale 01 OFF Reason Unknown

Victoria Victoria - Randenigala OFF Reason Unknown

WPS WPS - Old Laxapana 01 - Not Available

WPS WPS - Old Laxapana 02 - Not Available

Harshe

Typewritten Text

61

Harshe

Typewritten Text

1130POLPI-1

132.2

1170SAMAN-1

129.3

1210BOWAT-1

132.2

1770KIRIB-1

2220KOTMA-2

222.3

2230VICTO-2

224.4

2240RANDE-2

225.4

2250RANTE-2

225.4

32.7

32.6

3620BADUL-3

32.8

12.6

4252RANTE-G2

1790RATMA-1

132.4

1300KELAN-1

132.7

132.6

4760COL_F-11

10.9

4750COL_E-11

131.1

3500KOSGA-3

33.1

33.1

3670MATARA-3

132.0

33.3

132.0

3520NUWAR-3

33.3

1520NUWAR-1

130.7

1620BADUL-1

130.5

131.2

3540ORUWA-3

33.0

1670MATARA-1

125.8

132.3

1660EMBIL-1

1100LAX-1

132.0

131.3

3200UKUWE-3

3530THULH-3

33.0

32.7

217.2

2300KELAN-2

216.2

1540ORUWA-1

132.1

1530THULH-1

131.2

132.3

218.4

33.1

3860MADAM-3

132.6

225.3

1705NEWANU-1

133.5

1700ANURA-1

1850PANAD-1

132.4

1800MATUG-1

132.6

132.6

1240VAVUN-1

3240VAVUN-33

32.9

32.8

32.7

127.4

3400HAMBA-33

33.0

3660EMBIL-3

32.9

32.7

33.4

1160INGIN-1

127.0

3160INGIN-3

125.7

33.3

3700ANURA-3A

216.2

32.9

33.0

1710TRINC-1

33.0

132.1

32.9

32.9

131.8

32.7

3690HABAR-3

33.0

1740RATNAP-1

129.633.2

1595KHD -1

132.2

133.3

1600BOLAW-1

131.032.6

132.2

32.6

1840JPURA_1

132.4

3840JPURA_3

131.9

132.0

132.3

10.9

4435COL_A_11

3890DEHIW_3

33.0

3800MATUG-3

33.0

1810PUTTA-1

135.1

33.7

2.8

0.92.8

0.9

3.8

9.6

3.8

9.6

5.2

9.9

5.2

9.9

23.0

3.823.0

3.8

25.5

5.1

25.3

3.9

40.2

1.1

40.2

1.1

0.6

9.230.8

14.3

5.6

3.0

18.4

9.4

5.4

24.0

14.6

17.3

7.2

21.8

9.8

3.9

12.0 6.6

8.1

5.6

8.2

17.3

28.6

5.5

28.3

4.6

9.6

7.1

5.1

10.4

1.2

10.4

1.2

14.6

3.0

14.4

5.0

23.1

3.1

23.1

15.1

9.0

3.6

3.6

2.222.9

2.1

0.0

0.0

0.0

6.7

11.4

13.9

4.5

10.0

4.7

0.0

1.9 0.0

1.9

0.0

0.0

0.0

0.0

104.2

34.6

103.5

42.8

104.2

34.6

103.5

42.8

2.8

0.2

2.8

0.2

2.6

1.4

0.1

16.7

3.4

64.5

46.1

64.5

46.1

0.0

43.9

43.9

6.1

3.1

3.3

17.3

10.9 17.3

10.9

34.6

21.8

7.8

2.6

1.2

0.4

0.0

0.0

21.5

3.621.5

3.6

0.0

0.5

0.0

0.0

40.6

40.1

0.0 0.0

0.0

0.4

1.8

11.1

6.9

0.4

1.8

23.0

12.6

5.4

7.6

19.5

75.9

27.7

76.1

75.9

27.7

76.1

27.1

22.3

1.9

9.6

9.6

0.7

13.3

1.2

13.2

2.3

1.3

0.2

1.3

0.2

2.5

4.5

48.0

44.2

48.1

48.0

44.2

48.1

43.0

20.6

0.0

0.0

23.4

18.9

30.0

5.430.0

5.4

27.3

17.8

0.2

89.2

6.1

89.1

6.689.2

6.1

89.1

6.6

77.1

13.777.1

13.7

9.5

54.9

28.9 54.9

28.9

6.8

0.0

12.0

20.0

26.2

14.8 46.9

19.4

67.0

12.8

20.6

11.3

11.3

6.7

6.2

3.6

1.2

6.3

6.3

2.8

12.6

4.6

19.0

8.4

16.7

19.5

6.7

19.0

2.3

19.2

0.3

18.4

10.7

9.2

5.3

9.2

5.3

1.0

000 30.8

14.8

8.1

8.1

8.2

0.0

16.4

1.6

16.4

1.6

8.3

7.3

0.2

7.3

0.2

23.0

53.8

23.0

51.8

23.0

53.8

23.0

51.8

22.2

30.5

30.5

4.9

4.1

2.9

8.4

1

23.1

8.2

L

37.0

17.0

H

1

1

2.2

1

2.9

1

20.6

10.0

1 25.0

7.0R

1

1 22.9

14.1

1 23.4

16.2

1

17.3

6.7

1

24.0

13.4

1

15.6

8.1

1

17.3

5.6

1

1 34.6

1 4.5

2.3

1 10.0

1 0.0

1

1 34.6

20.1

1

1

0.0

0.0

1

18.4

9.4

1

24.5

1

7.8

2.4

SW 0.0

1

1

1.2

1

0.0

1 12.6

4.3

23.2

8.2

L

2

37.3

17.0

H

2

25.0L

60.0

25.0L

2

24.0

3.0L

2 24.5

2.0L

1

1

2 40.0

26.0H

1

2

1

22.9

16.7

SW

19.7

1

23.0

11.5

1 22.9

11.0

1

7.5

4.5

SW

1

20.6

1

25.7

1

0.0

0.0

1

27.3

16.6

1

24.0

13.3

1

1

9.5

5.7

1 8.4

6.2

1

1

1 13.9

8.6

1 20.0

11.4

1

20.6

9.0

1 26.2

10.7

1

11.7

6.1

2

5.4R

1

1

30.0

5.4R

1

19.0

11.0SW

1

16.7

8.4

1

1

18.4

1

1 0.0

1 22.3

12.3

1

1.1

1 83.0

SW

10.4

0.033.0

4.5

33.0

6.7

5.6

0.0

3121WIMAL-3B

0.0

60.0

26.9

3780VALACH_3

33.0

131.4

1780VALACH_1

6.8

19.9

0.4

16.2

131.7

27.1

6.6

3.2

3560PANNI-3

30.0

1590SAPUGA-1

18.5

3830VEYAN-33

1250RANTE-1

26.5

75.3

26.5

26.0

11.6

26.0

11.4

18.9

15.7

4.5

26.0

11.6

26.0

15.7

3.3

0.3

2.2

22.9

1 1.6

1.0

25.9

11.7

14.1

25.9

13.2

8.6

3600BOLAW-3

1

1

10.0

1

SW 0.0

1.9

20.0

3.9

19.6

6.5

3.6

1.2

8.4

5.0L

16.0

25.7

18.8

9.3

1 10.0

0.0L

6.2

1

1

10.0

1

1

5.0

0.0R

1

14.5

10.1

4.1

1

129.7

132.5

3880AMBALA

32.8

9.6

6.0

4.8

3.0

4.8

1

9.6

5.8

1

15.6

15.0

7.5

1900PNNALA

11.2

0.9

1.6

14.7

9.1

1910ANIYA

3910ANIYA

15.6

10.0

16.2

1

16.2

10.0

131.7

32.9

1

19.5

10.0

SW

0.0

SW

0.0

20.6

6.7

6.1

6.7

1.6

0.0

11.1

7.9

6.5

3710TRINC-3

SW

1

2

0.0

0.0

0.0

0.0

0.7

3250RANTE-3

3630BALAN-3

0.0

L

0.0

33.3

23.8

10.4

2.3

9.1

3565PANNI-C

10.2

10.0

15.9

2.0

32.6133.3

7.3

2.5

1 7.3

2.3

32.8

1.1 1.1

0.6

13.0

131.4

14.1

5.014.1

5.0

3440KATUNA-3

32.7

1

12.7

9.7

0.0SW

0.0

1 0.0

0.0

3

3811CEMENT

32.8

16.2

131.1

11.2

6.8

6.8

86.5

30.7

86.5

30.7

87.2

14.5

87.2

14.5

8.2

1

1 10.0

0.0L

20.0

2580KOTUG-2

6.1

3.5

SW 0.0

1

219.2

32.6

18.9

216.1

32.9

11.4

4.5

14.1

1

1.3

13.9

7.8

1920SUB-C

132.7

4920SUB C-11

4.0

1

11.0

1760COL_F-1

8.0

33.2

8.0

4.4

11.0

1500KOSGA-1

15.1

22.2

13.7

3.5

13.6

5.0

10.4

8.2

23.0

3.9

22.7

2.0

23.0

3.9

19.8

1

190.0

1.0

000 174.3

29.1

4811PUTT COAL-2

19.8

1 0.0

0.0

43.0

1 15.6

11.2

52.9R

11.4

12.0

0.3

1651GALLE-2

10.9

43.5

0.0

0.0

0.0

0.0

16.7

29.3

32.8

1

5.7

3.2

3.3

1

1

1

1

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

4310SAPUG-P

11.0

1 48.0

32.0H

11.0

1

26.5

20.0H

2 35.5

20.0H 48.0

27.0 62.0

31.0

0.6

32.6

1

8.0

1.0

7.3

15.4

2.8

7.3

4.7

8.0

2560PANNI-2

132.2

2

60.0

19.4R

3

60.0

19.4R

2.8

1550KOLON-1 2

3.4

6.7

0.0

10.9

3302KELAN-3B

1650GALLE-1

2.4

9.2

20.6

4.6

20.6

4.6

1

2.5

3405HAMBA-33

1400HAMBA-1

127.6

4.0

3340BELIATT-3

126.7

1.1

1340BEATT-1

15.3

2.9

32.8

129.8

3.1

19.5

1150AMPA-1

3150AMPA-3

4251RANTE-G1

12.5

1120WIMAL-1

3120WIMAL-3

1110N-LAX-1

6.1

3.3

3650GALLE-3

129.5

3651GALLE-3B

6.7

129.3

1640DENIY-1

3640DENIY-3

3740RATNAP-3

1630BALAN-1

1140CANYO-1

132.0

1.4

1690HABAR-1

3245VAVUN-33

2.3

0.3

1200UKUWE-1

8.5

24.6

3770KIRIB-3

33.1

SW

130.6

0.0

5.6

132.8

131.1

22.7

2.0

2705NEWANU-2

3810PUTTA-3

0.0

4305KERAWALA-G

14.4

1680KURUN-1

3680KURUN-3

SW

75.3

32.8

1860MADAM-1

131.2

4810PUTT COAL-1

1580KOTUG-1

2830VEYAN-2

1830VEYAN-1

13.5

5.7

32.6

3701ANURA-3B

SW

2810PUTTALAM-PS

224.4

1.0

430

11.2

3581KOTU_NEW-3

3580KOTUG-3

32.6

3510SITHA-33

23.4

11.7

1440KATUNA-1

3900PANNAL

15.9

0.0

24.0

14.1

3590SAPUG-3A

33.0

4311SAPUG-P2

1310SAPUG-1P

1870K_NIYA-1

3870K-NIYA-3

SW 0

.0

3820ATURU-3

Present Transmission Network

0.9

1880AMBALA

10.8

1420HORANA_1

131.8

3420HORANA_3

132.2

1890DEHIW_1

20.6

1435COL_A_1

7.0

7.0

9.0

13.9

3301KELAN-3A

30.5

0.0

15.1

3850PANAD-3

12.3

3790RATMA-3A 1560

PANNI-1

10.9

0.0

0.2

1510SITHA-1

15.1

3550KOLON-3A

32.7

3551KOLON-3B

8.0

22.9

1750COL_E-1

2570BIYAG-2

2305KERAWALA_2

218.4

14.4

4306KERAWALA-S

0.9667

* 53.0

2.0

7.5

* 1

2.3

0.9667

1.0000 1.0166

* 53.0

2.0

40.7

7.5

* 1

2.3

6.3

6.3

40.7

1.0000

0.9833

3.2

17.3

4.1

* 2.8

0.7

1.0000

1.0000 0.9833

* 20.1

3.2

17.3

4.1

* 2.8

0.7

133.5

1.1000

1.0000 0.9833

* 54.6

21.5

34.3

35.1

* 2

0.4

1.0000 0.9833

* 54.6 21.5

34.3

35.1

* 2

0.4

10.6

1.0000

1.0000 1.083357.2

23.0

53.4

* 0.0

0.0

1.0000

1.0000 1.0833

* 23.0

57.2

23.0

53.4

* 0.0

0.0

* 23.0

4300GT 07

2222BARGE-2

3300KELANI-3

1.0000

1.0000 1.0493

* 48.0

44.2

48.0

41.7

* 0.0

0.0

1.0000

1.0000 1.0493

* 48.0

44.2

48.0

41.7

* 0

.0

0.0

4302KCCP ST

4301KCCP GT

4303AES GT

4304AES ST

1820ATURU-1

3570BIYAG-3

10.6

1.0000

* 20.1

3705NEWANU-3

1570BIYAG-1

1.1000

40.7

21.2

32.9

128.1

1.01661.0000

1.0

450

4430COL_I_11

19.3

1430COL_I_1

33.0

1410KUKULE-1

Bus - VOLTAGE (kV)Branch - MW/MvarEquipment - MW/Mvar

100.0%RATEA

1.050OV0.950UV

kV: <=60.000 <=120.000 <=200.000 >200.000

suitable settings auto reclose

Documents

ceb transmission system

suitable settings

prospective settings

review of existing settings

ceb transmission network

transmission circuits

system stability

protection system