2 Protection Course - Overview Protection.pdf

DISTRIBUTION POWER SYSTEM PROTECTION 33/11kVSharul Amri Ismail & Sahari Abdullah (Sep 2008)

11

TNB Integrated Learning Solution Sdn Bhd - ILSAS

Ir. Azizuddin Zakaria – 28 Dec 200933/11kV Distribution Power System Protection For ST

33/11kV DISTRIBUTION POWER SYSTEM PROTECTION

FUNDAMENTAL OF PROTECTION


22



OBJECTIVES

At the end of the session, the participant will be able:

• To show the concept and application of protection system

• To explain the role of protection system in TNB• To show the types of protection relay used in TNB

system• To show the application of the relays in TNB system


33



WHY WE NEED PROTECTION?


44



Role of Protection

• Protect power system against any faults

• Detect “Fault”• Isolate faulty plant• Minimize damage• Minimize danger to people• Minimize supply

interruption


55



IDEAL PROTECTION SYSTEM FOR TNB SYSTEM

x x

x x

PMU 132/33 kV

PPU 33/11 kV

PE 11/0.415 kV

X XX

X

-bus bar protection

-cable/line protection

-transformer protection

All TNB equipment has to be protected!


66



• PROTECTION PRINCIPLESCriteria Definition

1. Fast • Fast fault clearance – Minimize the system interruptions or duration of system

disturbance– Improve system stability – Safety of Human & Equipment

2.Dependable/ Reliable

• Must operate for faults in the protected zone• Will operate correctly for all the faults for which it is designed to

operate3. Secure /

Stable• Must not operate/ stable for faults outside the protected zone,

power system disturbance• Will not mal-operate if no fault in the protected zone

4. Selective • Able to identify the faulty section and/or phase(s) of a power system

• Operate as much of the system as necessary to de-energize only distressed components of power system


77



• PROTECTION PRINCIPLES (continued)

Criteria Definition5. Sensitive • Sensitive enough to operate under minimum fault condition

• To consider minimum fault level• Low Level Fault may lead to more severe fault

6. Simple • Utilise minimal hardware and software logic to perform intended function

• Increase in hardware components may reduce the system reliability

7.Economical • The cost commensurate with the intended function and power system risk assessment


88



PROTECTION DESIGN PHILOSOPHY

• Fault Clearing System (FCS)

ProtectionEquipment/

RelayCT

VT

TE

DC System

TripCoil

CBMechanism

Protection System

Circuit Breaker

DC System

TE

CT – Current TransformerVT – Voltage TransformerTE – Telecommunication EquipmentCB – Circuit Breaker


99



• Fault Clearing Requirements– Maximum Fault Clearing Time (MFCT)

• Main Protection Function

Voltage Level (kV)Equipment

33/22/11

Substation 150ms

Circuit 600ms


1010



BASIC COMPONENT

• SENSING DEVICECURRENT TRANSFORMERVOLTAGE TRANSFORMER

• RELAY DECISION MAKER - TRIP OR NOT ?

• CIRCUIT BREAKERFAULT ISOLATION


1111



PROTECTION ISOLATION COMPONENTS

CIRCUITBREAKER SENSING

DEVICE

RELAYTRIP


1212



TYPE OF PROTECTION• Unit Protection

- operates on differential principle- has defined ‘zone protection’ determined by CT- must be stable during external fault

• Non-unit Protection– Simpler and cheaper– Requires time coordination between various stages– Long clearance time for faults close to source


1313



UNIT PROTECTION

CB CT CT

SS2

ZOP CB

FaultTRIPSS1 TRIP

Discrimination by zone!

RELAY


1414



SS1 SS2SS3

SS4

0 sec0.5sec

1.0sec1.5sec

Fault

NON-UNIT PROTECTION

Discrimination by time factor!


1515



LIST OF UNIT AND NON UNIT PROTECTION

• Unit Protection– Current Differential / Pilot wire relay

(7SJ610, Solkor Rf, Solkor N)– TX Differential (SEL 587, 7UT512)– TX REF (SPAE 010, 7VH600)

• Non Unit Protection– OCEF (7SJ602, P123)– SBEF (7SJ602, CAU)– Directional OCEF (SEL351A)


1616



MAIN & BACK UP PROTECTIONMain protection Back up protection

Transformer -TX Diff-TX REF-TX Guard

-OCEF- SBEF

Cable/line -Current Differential / Solkor Rf- High Set OCEF

-OCEF-SBEF

Bus bar - Low/High impedance- Arc protection

-OCEF


1717



RELAY OPERATING TIME• OCEF – 1.2 s (outgoing feeder PMU)

0.4 s (outgoing feeder PPU) -0.8 s (incomer TX 33/11 kV PPU) -

• SBEF - 2 to 2.5 s for 1st stage- 5 s for 2nd stage

• REF – 50 ms• TX Diff – 50 ms• Current Diff – 12 ms• Arc protection – 7 ms


1818



PILOT WIRE / CURRENT DIFFERENTIAL RELAY

• Use circulating current principle (Solkor Rf)

• Use voltage balance priciple(Translay H04)

• Is a unit protection• Need communication channel• Operation by comparing the current magnitude

of both end


1919



BASIC OF DIFFERENTIAL SCHEMEFLOW OF FAULT CURRENT OUT OF ZONE

R

CB CBCT 600/1 CT 600/1

5A 5A5A5A 5A 5A

FAULT3000A

0A

5A 5A


2020



BASIC OF DIFFERENTIAL SCHEME

R

CBCT 600/1 CT 600/1

FLOW OF FAULT CURRENT IN ZONE

CB

FAULT3000A 0A 0A5A 5A5A 0A

5A

5A 0A


2121



TRANSLAY – BALANCE VOLTAGE

SSA 1 SOURCESSB

CT CT

T T

CB

CBF

OPERATE NO OPERATION


2222



OCEF• The cheapest protection relay• Available in 3 OC, 1 EF and 2OC, 1 EF• Use Standard Inverse Definite Minimum

Time characteristics


2323




2424



2 O/C 1 E/F

O/C O/C

E/FEARTH BONDING

R

B

Y

OCEF BASIC DIAGRAM

2 OC and 1 EF is sufficient to cover fault

for all 3 phases


2525



OC OPERATION2 Phase fault

OC OC

EF

CT

R

R – Y Fault

Y

B


2626



OC OPERATION2 Phase fault

OC OC

EF

CT

RX

R – B Fault

CT

CTYX

X B


2727



EF OPERATIONSingle phase fault

OC OC

EFB – E Fault

EARTH

X

X

XVCB =


2828



STANDBY EARTH FAULT (SBEF)

• Use Definite Time Characteristics• Set normally between 2-2.5 s for 1st stage

and 5 s for 2nd stage, depending on coordination studies

• Is a back up protection


2929



SBEF CHARACTERISTICS


3030



BASIC OVERALL TRANSFORMER PROTECTION

POWER TRANSFORMERBREAKER BREAKERCT CT

REF

DIFF

SBEFINTERPOSINGCT

STAR

DELTA


3131



Power Transformer (132/33kV or 132/11kV) - HVProtection

ClassificationDevice

DesignationProtection Device

87T64REF/HV

51OCTXG

* 50BF/1 Circuit Breaker Failure Protection* 50BF/2 Circuit Breaker Failure Protection

Transformer Biased Differential ProtectionMain ProtectionTransformer Restricted Earth FaultOvercurrent ProtectionTransformer GuardsBucholz (Main & OLTC Tanks) – 63BWinding Temperature (HV/LV) – 26WTOil Temperature - 26OTPressure Relief Device – 63PRD

Backup Protection

Requirement in TNB COP Ed.2Note* : For Gas Insulated Switchgear (GIS) Substation Only


3232



Power Transformer (132/33kV or 132/11kV) - LVProtection

ClassificationDevice

DesignationProtection Device

Main Protection 64REF/LV51OC+51EF

64SBEF

Transformer Restricted Earth FaultOvercurrent & Earth Fault ProtectionBackup ProtectionTransformer Standby Earth Fault


3333



TX Differential• Is a unit protection• Usually located at 33 kV CRP• Use current circulating method• Operated by comparing the magnitude of

current of both ends


3434



BASIC OF DIFFERENTIAL SCHEME (through fault)

R

CB CBCT 200/1 CT 600/133/11 kV6000A2000

10A 10A 10A10A10A 10A

FAULT6000A

0A - relaystable

10A 10A


3535



BASIC OF DIFFERENTIAL SCHEME (in zone fault)

R

CB CBCT 200/1 CT 600/133/11 kV

0A 0A10A6000A

2000 0A

10A 10A 0A

10A relay operates

10A 0A


3636



RESTRICTED EARTH FAULT (REF)

• Is a unit protection• Usually located at 11 kV CRP• Has 2 types

– Voltage operated– Current operated


3737



RESTRICTED EARTH FAULT SCHEME FOR STAR WINDING

REF protected zone


3838



REF (OUT ZONE FAULT)

earth

CT 600/12400A

4A

4A4A

EARTH FAULT OUTSIDE ZOP2400A

RELAY STABLE 0A

CT 600/1 4A

4A 4A

2400A


3939



earth

CT 600/1

EARTH FAULT INSIDE ZOP2400A

RELAY OPERATES

4A

2400A

CT 600/1

0A

4A0A

4A

2400A

REF (IN ZONE FAULT)

4A

0A


4040



2400A

earth

CT 600/1

4A2400A

REF (PH-PH FAULT)

4A

PH - PH FAULT OUTSIDE ZOP2400A

RELAY NO OPERATION/STABLE

CT 600/1


4141



earth

CT 600/12400A

2400A

REF (PH-PH FAULT)

PH - PH FAULT INSIDE ZOP2400A

RELAY NO OPERATION/STABLE

CT 600/1


4242



DIRECTIONAL OCEF• Directional Control at ‘C’ and ‘D’

• Relay ‘D’ does not operate due to current flow in the reverse direction.

51 A 67C

51 B 67D

LOAD

I1 + I2I1

I2


4343



ARC PROTECTION• Input from light sensor and current

transformer• Light input coming from flashover• Current input coming from fault current

magnitude• Tripped if both conditions existed• Tripping time 7 ms


4444



ARC protection – Two incomers VAMP 221 VAMP 221

CB1 CB2

CB3

Ib>

T2

T1

T2

T1

X2X1

VX010VX010


4545



TNBD PRACTICE• TX 33 /11 kV Protection

– Main protection• TX DIFF, REF (>5MVA TX)• TX Guard

– Bucholz – Main Tank & OLTC– Pressure Relief Device– HV and LV winding temperature– Oil temperature

– Back up protection• OCEF• SBEF


4646



TNBD PRACTICE

• Cable Protection– Main protection

• Current Differential / Pilot wire relay• Directional relay

– Back up protection• OCEF• SBEF


4747



TNBD PRACTICE

• Overhead Line Protection– Main protection

• OCEF High Set with A/Reclose– Back up protection

• OCEF IDMT• SBEF


4848



TNBD PRACTICE• Bus bar Protection

– Main protection• Recently used Arc Protection• Reverse blocking scheme (not yet widely used)

– Back up protection• OCEF


4949



PROTECTION SYSTEM USED IN TNB SYSTEM

PMU 132/33 kV

PPU 33/11 kV

x x

x x

PE 11/0.415 kV

X XX

X

TX 33 / 11 kV > 5 MVAMain and back up protection used/availableTX 33/11 kV < 5 MVAUsed quenchol fusesLocal TXUsed OCEF


5050



PMU 132/33 kV


PPU 33/11 kV

x x

x x

PE 11/0.415 kV

X XX

X

Underground cable 33 kVMain protection are active unless pilot wire is notavailableBack up protection used (OCEF)Underground cable 11 kVMain protection translay H04 not widely used.Directional OCEF used for parallel feedersOnly used back up OCEFOverhead line 33 kVUsed OCEF with reclose / Auto recloser


5151



x x

x x

PMU 132/33 kV

PPU 33/11 kV

PE 11/0.415 kV

X XX

X

Bus barArc protection only recently usedMost TNB sub station no arc protectioninstallation/available Only depends on back up OCEF as solely protection



5252



Protection Relay Location

•Tx Differential

•Tx Guard

•OC/EF

•Master Trip

•Solkor R/RF

•OC/EF

•Master Trip

•Tx Differential

•Tx Guard

•OC/EF

•Master Trip

•OC/EF

•REF

•Master Trip

•SBEF Tx1

•SBEF Tx2

•Master Trip

•OC/EF

•Translay

•Master Trip

NER

33kV

•OC/EF

•REF

•Master Trip

Tx1 Tx2

1HO 2HO

31 32

11kV Outgoing

33kV Outgoing

Bus Section

11kV


5353



2 Protection Course - Overview Protection.pdf

Documents

Transcript of 2 Protection Course - Overview Protection.pdf