02 ADVC_206B_FV Protection Coordination and Timing

7/28/2019 02 ADVC_206B_FV Protection Coordination and Timing

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Protection Discrimination and Timing

On the ADVC Controller

With a flexVUE Operator Interface


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Schneider Electric 2 < AUTHOR >

The purpose of this presentation is to show howprotection discrimination is achieved with the ADVCController.

The following topics will be covered:

Discrimination by time.

Discrimination by current.

Discrimination by time and current.

Standard and non standard curves available on the ADVC.

How protection curves can be modified to assist inachieving coordination and discrimination.

Discrimination Overview


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Principle of Discrimination

Correct discrimination ensuresthat the faulty part of a power

system only is isolated as quicklyas possible, leaving all of thefault-free parts energised.

Fault F1 may be detected by

protection devices A, B, C and D.

Time to Trip for D should beshorter than C which is shorterthan B etc.

This ensures that only the circuitnecessary to clear the fault isdisconnected by either primary orback-up protection.

A

B

C

D

F1


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Discrimination Interval

The difference in operation time

T between two successive

protection devices is thediscrimination interval.

It takes into account

-Breaking timeTc

of the

downstream circuit breaker, which

includes the breaker response time

and the arcing time.

-Time delay tolerances dT

-Upstream protection unit overshoot

time tr.

-A safety margin m.

T should therefore satisfy the

relation:

-T Tc + tr +2dT + m

Example:

-Tc = 50 ms

-dT = 30 ms

-Tr = 30 ms

TB TA

dTB dTATcB m trA

30ms 30ms 30ms50ms 60ms

Discrimination Interval T

200 ms


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Time to Trip

The time delay between Pickup

and Trip is determined by the

protection settings applied.

The Time to Trip is dependant on

whether the active trip is set to:

-Definite Time

-Instantaneous Only

-Inverse Time

Possible Active Trips

-Trip 1

-Trip 2

-Trip 3

-Trip4

-Single Shot

-Work Tag


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Trip Settings on the flexVUE Operator Interface

PROTECTION MENU

Protection Global

Protection Trip Settings

Protection Control

Directional Elements

ENGINEERING MENU

Protection menu

Configuration menu

Power quality

Telemetry menu

Automation menu

Measurements menu

PROT TRIP SETTINGS

Trip 1, 2, 3, 4

(Reclose time, Protection &

reset curve for P, E, SEF,

NPS)

Single Shot

(SS reset time, Protection

& reset curve for P, E, SEF,

NPS)

Work Tag

(Protection & reset curve

for P, E, SEF, NPS)

Under Over Frequency

(Under, Over, Normal

Close, Low V inhibit,

Bushing)

Under Over Voltage

(Under, Over, Config)

Loss of Phase

(On/Off/Alarm, Voltage,

Timeout)


7/39Schneider Electric 7 < AUTHOR >

Types of Discrimination

Various means can be used by

the ADVC controller to implement

discrimination between devices.

Time-based discrimination

-Definite Time

Current-based discrimination

-Instantaneous Only

Discrimination based on time and

current-Inverse Curves



Time-Based Discrimination



Time-Based Discrimination

Time-based discriminationconsists of assigning different

time delays to the overcurrentprotection units distributedthrough the power system.

The closer the relay is to thesource, the longer the time delay.

Advantages:

-Provides back-up

-It is simple

Drawbacks

-The longest fault clearance timeoccurs for faults closest to thesource where the fault level ishighest.

A

B

C

D

F1

DT = 0.2s

DT = 0.5s

DT = 0.8s

DT = 1.1s



Trip 1 Phase Protection Definite Time


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1.0 s Definite Time Curve

> 200A

1.0s 4.00


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1.0 s Definite Time Curve with x4 Instantaneous

>800A

1.0s

200-800A


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Current-Based Discrimination


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Current-Based Discrimination

Current-based discrimination

works on the principle that the

further the fault is from the source,the lower the fault current will be.

The threshold is set to a value

lower than the minimum short-

circuit current caused by a fault inthe protected section and higher

than the maximum current caused

by a fault in the next section.

Each protection device should

only pickup for faults located in

the section of feeder immediately

downstream.

A

B

C

D

F1

IsC=490A

IsB=780A

IsA=960A

IscAmin = 1000A

IscBmin = 800A

IscCmin = 500A


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Current-Based Discrimination with Transformers

For sections of lines separated by

a transformer, it can be of benefit

to use this system since it issimple, cost effective and fast

(instantaneous).

IsA < IscAmin

IsA=960A

F1

IscAmin=1250A


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Protection devices should be set

such that:

IscBmax < IsA < IscAmin

Time delays TA and TB are

independent and TA may be

shorter than TB

Drawbacks:

-The upstream protection device (A)

does not provide back-up for the

downstream device.

-In practice it is difficult to define the

settings for two cascading

protection devices and still ensure

discrimination unless there are

transformers between sections.

IsB=600A

IscBmax 760A

F1

IscAmin=1250A

IsA=960A

TA=0.6s

TB=0.9s


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IsB=600A

IscBmax 760A

F1

IscBmax < IsA < IscAmin

IscAmin=1250A

IsA=960At

I

AB

IsB IscB

maxIsA IscA

min

TA

TB

TB=0.9s

TA=0.6s

To ensure discrimination:

1.25 IscBmax < IsA < 0.8 IscAmin


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Trip 1 Phase Protection Instantaneous Only


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Instantaneous Only Curve

0.3

200A


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Instantaneous Only Curve with Minimum Time

0.3

> 200A

0.30s


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Discrimination by Time and Current


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Discrimination by Time and Current

A combination of both time andcurrent discrimination can be

used to achieve totaldiscrimination with built-inredundancy or back-up.

In the example below device Buses Definite Time and device Auses Definite Time with anInstantaneous multiplier.

A

B

t

I

T

B A

A DT

A Inst

B DT

IsB IsA IscB IinstA IscA

Feeder 1

Feeder 2

A is thePrimary

protection

device for

Feeder 1

Back-up for

feeder 2

B is the

Primary

protection

device for

Feeder 2


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IDMT Inverse Time Curves

With this characteristic, the time ofoperation is inversely proportional

to the fault current level and theactual characteristic is a functionof both time and currentsettings.

ADVC Inverse Curves

-IEC255Standard Inverse

Very Inverse

Extremely Inverse

-IEEE

Standard Moderately Inverse

Standard Very Inverse

Standard Extremely Inverse

-TCC

42 Non-standard curves

I

t

1 1

0

1

0

0

1

0

0

0

0.01

0.1

1.0

10.0

IEC255 I C


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IEC255 Inverse Curves

IEC60255 Standard Curves

Standard Inverse Time

Time to Trip = 0.14 / ( Im0.02 1)

Very Inverse Time

Time to Trip = 13.5 / ( Im 1)

Extremely Inverse Time

Time to Trip = 80.0 / (Im2 1)

IEC255 Inverse Curves

IEEE I C


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IEEE Inverse Curves

IEEE Standard Inverse Curves

Moderately Inverse Time

Time to Trip = (0.0515( Im0.02

1)) + 0.114

Very Inverse TimeTime to Trip = (19.61 / (Im2 1))

+ 0.491

Extremely Inverse Time

Time to Trip = (28.2 / (Im2 1))

+ 0.1217

IEEE Inverse Curves

TCC N St d d I C


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TCC Non-Standard Inverse Curves

The group of 42 TCC non-standard curves are generally

plotted curves that do not complyto a formulae.

-TCC136

-TCC101

-TCC131

-TCC121

-TCC161

-TCC200

Selection of TCC Inverse Curves

S l ti I C


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Selecting an Inverse Curve

IEC255 St d d I C


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IEC255 Standard Inverse Curve

400A x2

10.03s

2000A x10

2.97s

2.00

IEC255 St d d I C TM 2


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IEC255 Standard Inverse Curve TM x2

2.00

400A x2

20.06s

0.20

2000A x10

5.94s

IEC255 St d d I C TM 0 2


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IEC255 Standard Inverse Curve TM x0.2

2.00

400A x2

2.006s

0.20

2000A x10

0.59s

IEC255 St d d I C TM 0 2


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IEC255 Standard Inverse Curve TM x0.2

2.00

400A x2

2.006s

0.20

2000A x10

0.59s

0.80

IEC255 Standard Inverse Curve Min Time = 0 8s


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IEC255 Standard Inverse Curve Min Time = 0.8s

2.00

400A x2

2.006s

0.20

2000A x10

0.80s

0.80

0.20

IEC255 Standard Inverse Curve Add Time = 0 2s


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IEC255 Standard Inverse Curve Add Time = 0.2s

2.00

400A x2

2.206s

0.20

2000A x10

0.80s

0.80

0.20

IEC255 Standard Inverse Tripping Times


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IEC255 Standard Inverse Tripping Times

BCDE

40A

IEC255SI

200A

IEC255SI

A

F1

400A

F2

2500A

Current Trip

ACR Setting Multiple Time

Fault F1 400A B X 10 2.97s

E X 2 10.03s

Fault F2 2000A E X 12.5 2.7s

Effect of Applying Time Multiplier = 0 2


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Effect of Applying Time Multiplier = 0.2

BCDE

40A

IEC255SI

200A

IEC255SI

A

F1

400A

F2

2500A

Current Trip Time

ACR Setting Multiple Time Multiplier

0.2

Fault F1 400A B X 10 2.97s 0.594s

E X 2 10.03s 2.006s

Fault F2 2000A E X 12.5 2.7s 0.54s

Effect of Applying Minimum Time = 2 0s


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Effect of Applying Minimum Time = 2.0s

BCDE

40A

IEC255SI

200A

IEC255SI

A

F1

400A

F2

2500A

Current Trip Time Minimum

ACR Setting Multiple Time Multiplier Time

0.2 2.0s

Fault F1 400A B X 10 2.97s 0.594s 2.0s

E X 2 10.03s 2.006s 2.006s

Fault F2 2000A E X 12.5 2.7s 0.54s 2.0s

Effect of Applying Additional Time = 1 0s


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Effect of Applying Additional Time = 1.0s

BCDE

40A

IEC255SI

200A

IEC255SI

A

F1

400A

F2

2500A

Current Trip Time Minimum Additional

ACR Setting Multiple Time Multiplier Time Time

0.2 2.0s 1.0s

Fault F1 400A B X 10 2.97s 0.594s 2.0s 2.0s

E X 2 10.03s 2.006s 2.006s 3.006s

Fault F2 2000A E X 12.5 2.7s 0.54s 2.0s 2.0s

Applying an Instantaneous Modifier


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Applying an Instantaneous Modifier

BCDE

40A

IEC255SI

200A

IEC255SI

A

F2

3000A

Current

ACR Setting

Multiple

Trip

Time

Instantaneous

Multiplier

Additional

Time

Minimum

Time

X 14 1.0s 2.0s

Fault F2 3000A E X 15 2.52s


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Protection Discrimination - Review

The main objectives of Protection Coordination are:

When a fault is detected, only the smallest part of the network necessary to

isolate that fault should be disconnected.This means that for a given fault the primary protection device should operate

in the shortest possible time to clear the fault.

If the primary protection device fails to clear the fault in the expected time, aback-up device should clear the fault in a longer but still acceptable time.

Three types of discrimination can be used by the ADVC controller:

1. Discrimination by Time Definite time2. Discrimination by Current Instantaneous Only

3. Discrimination by both Time and Current Inverse Curves

Definite Time curves can be modified by:

Instantaneous

Instantaneous Only curves can be modified by:Minimum Time

Inverse Curves can be modified by:

Time Multiplier, Instantaneous, Additional Time and Minimum Time.

Documents

02 ADVC_206B_FV Protection Coordination and Timing