Modern Power System Protection Requirement Solutions

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© ABB GroupJune 13, 2013 | Slide 1

Quire and Solutions

Power System Protection-Requirement & Solutions

Jianping Wang, ABB, 2013-06-14 KTH

E-mail: [email protected]



Part 1: Power System Protect ion Requ irement

Part 2: Protect ion App l icat ion Solut ions

Part 3: Modern Protect ion and Future Trends

Contents



Tradit ional gr id Smart Grid

Transition of Modern Power System Network:

-Renewable Energy Sources added in the network

-Multiple load flow directions

-More HVDC and FACTs connections

-Challenges for Power System operators



Protect people and propertyaround the power system

Protect equipment, lines etc.in the power systems

Separate the faulty part fromthe rest of the power systemsto keep system stable operation

U I

Protection Relay

(Intelligent ElectronicDevices (IEDs))

Circuit Breaker

CTVT

Power System Protect ion-Purpose and Ac t ions

VT=Voltage transformer

CT=Current transformer



Relay time 0,02 seconds

Breaker time 0,06 seconds

Voltage interruption 0,5 seconds

UR

US

UT

IR

IS

IT

Lightning

stroke

Protection System Operation Cycle



Circuit Breaker

Trip

Coil

Circuit

Breaker

Mecha-

nism

DC-System

Protection

Equipment

CT

VT

TE

Protection System

Fault Clearance System

Protection System Structure



Benefits of Clearing of Power System Faults

Reduce the hazard for personnel

Reduce the hazard for property

Reduce the damage at fault location

Reduce the risk for power interruptions

Operate the power system closer to

limits



Shunt faults

Serial faults

L1

L2

L3

L1

L2

L3

IS

IT

1- phase faults

3- phase faults

11 fault cases can be detected with

6 measuring loops for line protection

2- phase faults

Faults Classification



• Single phase to ground 80%• Two phases to ground 10%

• Two phase 5%

• Three phase 5%

• Transmission lines 85 %

• Busbars 12 %

• Generators / transformers 3 %

Transmission systems

Faults per 100/year

Transmission linesType of fault

Fault Statistics

• Hydro turbine 6,2• Hydro generator 14,6

• Transformer 2-3

• Breaker 1

• Current/ Voltage transformer 0,2



Fau lt types

• Transient faults

– 80- 85%of all faults in transmission lines

– Mainly caused by lightning strokes ( 0,2 - 3/ 100 km/year )

– Additional faults by birds, trees, galloping lines etc.

– Disappears if the line is disconnected and reclosed

• Persistent faults

– Broken conductor or insulator

– Fallen tree

– Has to be localised and repaired before the line can be

reenergized



R

S

T

20 kA

Speed

500kV

Short circuit power:

P = 3 x x 20 = 17300 MVA

3

500

Limits stress anddamages on lines,

busbars and equipment

1kA

Inductionu

U = 1 kA x 1 = 1000 V

Sensitivity

1

Limits the risk to injurepeople and reduces the risk

for long term damage

Selectivity

Limits the consequencesfor the power system

Main Requirement on Power System Protection



Personal Safety

Minimize the risk of personal injuries-Examples of current levels

10 mA: there will occur cramp in muscles

20-40 mA: there can be a stop of the breathing of the person

subjected to current flow through the body

50-3000 mA:very dangerous condition, can lead to death within a

few minutes

Safety regulations often state:

Maximum allowed fault duration

Sensitivity of the protective relays

Earth fault protection in general is highly required with goodsensitivity



Fault Clearance Time

Long fault clearance times increases:

The risk for transient instability in the power

system

Thermal stress on equipment in the powersystem and

Risk for personal injuries.



Trans ien t Stab i l i ty-Examp le

Angle

Time

t1

t2

t3

t4

t5

Fault time t < t < t < t < t1 2 3 4 5



0 60 100 200 ms

1-phase faults

3-phase faults

2-phase faults

Fault disconnection time

Power flow

MW

Relay pro tect ion : Speed

G G

G G

Time restraints for fault disconnection

Stability limit MW (Typical case)

• Stability

• Less damage

•

Less stress• Less ionization

Speed



Relay Protect ion: Sens it iv i ty

Example: High ohmic ground faults in power lines,

interturn faults in transformers

f 1.4

R = 28700

I * L

L = length of the arc

[meters] andI = fault current [A]



L2

L1

L3 L1

L2

L3

Protect ion : Select iv i ty

• Selectivity is the ability of a protection system to detect a

fault in a specified zone of a network and to trip the

appropriate circuit breaker(s) to clear this fault

• Simultaneous faults in parallel lines-right side

- Single pole tripping and auto reclosure

- With correct selectivity the power flow isnot interrupted

Z<

L3-N

L1-N

Z<

Z<

Z<

Z<Z<

Z< Z<

G L

Power flow



Power System & Protection System Reliability

Power Sys tem Rel iabi l i ty -Referr ing to Interrup t ion

of power supply to customers

High rel iabi l i ty resul ts in high cost in g r ids

Low rel iabi l i ty resu l ts in more interrupt ion to

customers

Protect ion Sys tem Rel iabi l i ty

Dependabi l i ty-Tr ip on Internal Faults

Secu rity -Stable for External Fault s

Rel iable pro tect ion sys tem

Main Protect ion, Local Backup, Remote Backup



Rel iabi l i ty o f Protect ion System

RELIABILITY

DEPENDABILITY

SECURITY

Failure to trip

Unwanted trip

(spontaneous)

Unwanted trip

(at system fault)

Wrong settings

Inadequate

measuring

principle

Inadequate

operating

conditions

Faulty device



Non redundant protect ion sys tem

CABLE

CABLE

Trip coil CABLE

CABLE

CABLE

+ -

Protective device

Tripping unit

CT

VT

CB



Redundant protection system

Tripping u.2

Main 1

Trip coil 1

Trip coil 2

Main 2

+ -

+ -

Battery 1

Battery 2

CABLE

CABLE

CABLE

CABLE

CABLE

CABLE

CABLE CABLE

C A B L E

C A B L E

Tripping u. 1



Non-redundant and redundant pro tect ion

schemes

I

II

I

I II

Non-redundant protection scheme

Redundant protection scheme with1 out of 2 operating condition

Redundant protection

scheme with 2 out of 2

operating condition



Rel iabi l i ty of non-redundant and redundant

funct ions

P r o b

a b i l i t y o f f a i l u r e t o o p e r a t e

( d e p e n d a b i l i t y )

Probability of unwanted operation (security)

R

RR

RR

IMPACT OFSELF-SUPERVISION



Failure Rate of Protection Relays

BATHTUB CURVE

0

20

40

60

80

100

0 20 40 60 80 100

Time

F a i l u r e r

a t e



Part Two: Power System Protect ion

Appl icat ions



Current transformers:Magnetic ,1 Ampere or 5 Ampere secondary

Optical transducers with serial data protocols

I nputs of A Protection Relay

Current:

Voltage: Voltage transformers:

Magnetic, 100 V, 110 V secondary

Capacitive, 100 V, 110 V secondary

Optical transducers with serial data protocols

Via measuring transducers

Protection range: DC- 300 Hz (typical)

Disturbance recorders: DC- 1- 5 kHz

Frequency:

Binary: From signalling contacts or fiber optic inputs

HV equipment

Communication equipment



SaturationCurrent transformer designation Type TPX, closed iron core

Type TPY, iron core with remanence

air gap ( 1 or 2 small)

Type TPZ, linearised iron core

(A number of airgaps)

CT Saturat ion Inf luence

Phase- and amplitude faults

True secondary currentTPX

TPY TPZ



VT Trans ient In f luence:

10 % of U

after 1 period (20 ms)

Transients from Capacitive Voltage Transformers (CVT)

Primary short circuit

True primary voltage

Transients from CVT



Transients in the power system:

Fault incidence



Harmonics in the power system affects the accuracy

5th harmonic 10%

100 %

RMS-measurement: <± 2 %

Mean value measurement: <± 20 %

7th harmonic 10%



TransmissionDistance protection

Differential protection

Phase comparison protection

Transient measuring based protection

Distribution

- Over current protection: Directional/Non-Directional- Differential protection

Line Protection: General Practice



• Is the most used protection scheme in

general networks

• Operation is based on the information

from only one terminal

(communication independent)

•

Non-unit protection scheme, used also asa local or remote back up protection

• Short tripping times (between 0,75 and

1,5 cycle)

K

U I

Protected distance (zone)

Transmission Line protection: Distance protection



Z<

Uk

A Bshort circuitIkZk

Ufaultpoint = 0

ZK =Uk/ Ik

ZL =Line impedance

G

I

UXS XL RL

G

u = i . R +X . di

o. dt

Measuringprinciple:

ZK < ZL

Algorithm

Transmission Line protection: Distance protection



Z<

G

zone 1

zone 3

zone 2

Z<Z<Z<Z< Z<

zone 1

time delayed

zone 2

Maximum reacharound 80-90 %

Transmission Line Protection: Distance protection

time delayed

zone 3

Related Issues:

Switch on to faults

Power Swing Block

Weak-end infeed logic

Current reversal logic



Z<

G

B- zone 1time delayed

B- zone 2

Z<Z<

A- zone 1

time delayed

A- zone 2

Z<

With communication from B, thezone 2 in A can be accelerated,

i.e. no time delay in A- zone 2

B

A

Line protection transmission: Distance protection



• The measurement is based on thecomplete loop equations

• Independent setting for each zoneof:

– Reach in reactive direction – Reach in resistive direction for:

» phase to phase faults

» phase to earth faults

– Ground return compensation

– Directionality

R

xph - ph ph - E

K

Line protection transmission: Distance protection



diff

diff

Transmission Line Protection:Current differential protection



Current differential protection

L1L2L3

DL1

DL2

DL3

DL1

DL2

DL3

Digital communication withoptical fibres, direct or viamultiplexed channels

Digital communication viatelephone or micro wave

Issues in line differential protection:

Communication channels asymetry, Data

synchronization



Communication Schemes

Blocking

Permissive

Under-reach

Overreach

Unblocking

Unblocking

weak infeed

transient blockingOverreach



Auto -reclos ing (AR)

Most faults are transient

faults

Auto-reclosing will in this

aspect increases the

availability

It will also have a positive

impact on the system

stability0

10

20

30

40

50

60

70

80

90

100

Transient

faults

Permanent

faults

Series1

The distribution of transient and permanent faults

on the one utility 130 kV system during 1987-1996



Different winding arrangements

2 windings+ unloadedtertiary

3 windings Autotransformer + tertiarye.g.. Yy 6 d1

e.g.. YN Auto d1

2-winding transf.+ Auxiliary

transformer

Transformer Protection



Overload

Over voltage

Over excitation

Reduced System Voltage


Aging of insulation

Contaminated oil

Partial discharges in the

insulation

Transient over-voltages

Factors Contributing toInternal Faults

Abnormal Conditions

M i F ti i T f P t ti



Internal fault detection Differential protection

Over-current protection

Inter-turn fault detection

Restricted earth fault protection

Differential protection

Ground fault detection

Restricted earth fault protection

Earth fault protection

Abnormal condition detection

Overload protection

Over-excitation protection

Non-electrical fault detectionfor all internal faults

Thermal Relay

Buchholz Relay

Pressure Relay


Main Functions in Transformer Protection



Differential Protection-Main Protection for Transformers

Typical Modern Transformer Differential ProtectionFunction features



Transformer Inrush Current Stabilization

The second harmonic component appears

as a characteristic quantity in a transformer

inrush current. It is also possible to monitor

the shape of a current signal

Second harmonicstabilisation

Wave form stabilisation wave block

Transformer inrush current



ROA

MTA

3I0

ROA

reference isneutral current

operate forinternal fault

internal fault

restrain forexternal fault

-IN

3I0

zone of protection

IN

IL1

IL2

IL3

IFAULTIN 3I0

zone of protection

IN

IL1

IL2

IL3

IFAULTIN

3I0ROA

MTA

ROA

reference isneutral current

external fault

-INoperate forinternal fault

restrain forexternal fault

Internal fault External fault

Restricted Earth Fault Protection



Generator Protection Power plant layouts

G G GG

Typical Configuration of a Power Plant



yp g

G

Substation

Power plant

Busbar in Substation

HV - Breaker

Main Transformer Auxiliary Transformer

Generator Breaker

Excitation Transformer

Excitation System

Field Circuit Breaker

Turbine valve

Turbine - Generator

Earthing System



Fault Classification on Generators

Internal External

Stator Rotor Stator Rotor TurbineShort circuit Short circuit frequency

ground fault ground fault overvoltage negative

sequence

reverse power

interturn overexcitation loss of excitation

Allocated Protection Functions For Generators



Allocated Protection Functions For Generators

87 Differential

59 Over-voltage

24V/f Over-excitation

49S Stator Over-load

51V Voltage/over-current

64S Earth fault stator

Inter-turn

27/50 Dead Machine

Turbine

Rotor Stator

32 Reverse power

81O/U Frequency

46 Unbalanced

40 Loss of excitation

78 Pole slipping

64R Earth fault rotor

49R Rotor overload

Sing le Line Diagram for a Unit Protect ion Scheme



g g

G

87GT

87G

51V49S 4046 78 27/50

59 81 24V/f32

60

64R

64S

59N

24V/f

(1)

51N

87UAT

(1)

21

51T 51NT

Step-up

Transformer

Generator with

grounding system

Auxiliary

Service

Transformer

1

3

3

3

3

3

3

1

1

1

1

E l f D D t F il f T i b P t ti



Example of Damage Due to Failure of Trip by Protection



G

G

G GG

LOADG

Busbar Protect ion-Requirement

Security

• Stability for externalfaults

Dependability

• Correct operation forinternal faults

M i I i B b P t ti



Main Issues in Busbar Protection

CT Saturation has to be treated in a reasonable wayso that external fault with high through goingcurrents will not create in-correct operation onbusbar protection.

Switching mirror logic has to be reflected in the protection scheme so that change of busconfiguration will not create operation of busbar protection

Speed is also very important factor for busbar protection due to high disturbance created in busbarfaults.



Busbar Protect ion Development-Examples

High Impedance Differential Protection (Example:

RADHA)-The Same CT ratio required

RADSS & REB 103-Different CT ratios and loop

resistance

Low Impedance Differential (INX2,INX5, RADSB, &Competitors)

Numerical Low Impedance Differential

(example:REB500)

Numerical low Impedance Differential RED 521

Numerical low impedance differential REB670



Typical Busbar Protect ion Scheme for 220 kV



Four Zone Double Bus with two BC-CBs one BS-CB and one sectionalizing

disconnector with up to 18-20 feeder bays in the whole station

Optional Measuring Point

Four Zone Double Bus with two bus-coupler CBs and two

bus-section CBs and up to 20/21 feeder bays on each station side

Reserve 2

Main 2

Reserve 1

Main 1

.. ... .

Reserve 2

Main 2

Reserve 1

Main 1

.. ... .

Typical Busbar Protect ion Scheme for 220 kV

CT saturat ion after 1.3 ms, Example o f external



CT saturat ion after 1.3 ms, Example o f external

faults

0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22

-6

-5

-4

-3

-2

-1

0

1

2

3

x 104 Prov nr 72

P r i m a r y C u r r e n t [ A ]

Time [sec]

ItotIXTrip

Stable forexternal

fault!!!



Part Three: Modern Protection and Trends



DESIGN IS CHANGING

BUT

A BASIC IDEA REMAINS

PERFORMANCES

ARE IN GENERAL

IMPROVED

1000 2013 ACBC 1000 0



Electromechanical Relays 1903

Static Relays 1960

INX2 BBP 1966

Micro Processor Relays & INX5 BBP 1981

Numerical Generator Protection 1987

Numerical Protection &Control Devices 1991

Numerical HV Automation System 1991

Numerical Busbar & Breaker Failure Protection 1994

Fully Graphical HMI 1997

Automation System with Sensors & Actors 1998

Station ProtectionAdvanced Integrated Protection Functions 2001

New Series Protection Device with IEC61850 2006

And More 2013

F r om 1 9 0 3

t o2 0 1 3

Hardware Scheme of Modern Protection Relay



Hardware Scheme of Modern Protection Relay

A/D

Module

~~

Analogue

Module

~~

A/D6 I

6 U

3

3

3

3

ConversionInput

Comm-

uni-

cation

Logics

Main

Module

ProcessingGPS

Module

SynchBinary

Module

I/O

I/O

Binary

Module

I/O

CAN1Mbit/s

TRM AD1 NUM GSM BIM

PCU

OEMLDCM

Binary

Module

I/O

BIM BIM MIM PSM

I/O I/O I/O

BOMBOM

Binary

Module

I/OBinary

Module

I/OPower

Module

SupplymA

Module

Input

mAI/O

Modern Protection Products (IEDs)



Distribution Transmission

RE_ 670

RE_ 615

RE_ 630+RE_650

RE_ 60_

Modern Protection Relays

known as Intelligent Electronic

Devices (IEDS)

( )

ModernTransmission Protection and Control Portfolios



IEC 61850-compliant product portfolio (with KEMA

certificate)

Substation Products

MicroSCADA Pro, Station-HMI

Gateways, Remote control and data acces

Transmission & Distribution Protection & Control

IEDs for most applications Overhead lines

Underground cables

Multi terminal Circuits

Transformers & Reactors

Generators & Large Machines

Busbar & Breaker

Composite Objects

High Voltage Switchgear

Technology Evaluation-Yesterday, Today and Future



RTU RTU RTU

RTU RTU RTU

parallel,hardwired

cabling

parallel,hardwired

cabling

parallel,hardwired

cabling

Interbay Bus Interbay Bus

Process Bus

Station Bus Station Bus

Function Integration-Less Panels in Substation



12

4

5

8

39

12

4

3

8

39

6

4

3

4

39

6

2

3

4

32

3

1

7

2

Line

Busbar

Feeders

Controllers

1960 1970 1980 1990 2000 2010

6 8 C u b i c l e s ,> 1 8 0 D ev i c e s

6 6 C u b i

c l e s ,> 1 6 0 D ev i c e s

5 6 C u b i c l e s ,> 1 4 0 D ev i v e s

4 7 C u b i c l e s ,>

1 0 0 D ev i c e s

1 3 C u b i c

l e s ,> 5 0 D ev i c e s

Transformer

Control Room

Communication IEC61850



A Break through in SA IEC61850

A complete Substation Automation System



p y

SAS690

BCS690 BPS681BPS680 BPS683

Horizontal (peer-to-peer) communication



(p p )

GOOSE = Generic Object Oriented System-wide Events

Station

computer

Station

gateway

Protection

Process Interface Process Interface Process Interface

Control Protection Control Control &

Protection

GOOSE

Modern Digital Substation Structure Based on IEC 61850



Bay

Controller

IED

A

IED

A

Modern

Switchgear

Modern

CTs/VTs

Bay

Controller

IED

A

IED

A

Modern

Switchgear

Modern

CTs/VTs

Ethernet

Switch

Ethernet

Switch

Router switch

HSIEngineering/

Monitoring

IEC 61850-8-1 Stations bus

IEC 61850-9-2

Process bus

IEC 61850-9-2

Process bus

Network

Control

Center

Documents

Modern Power System Protection Requirement Solutions