TestingTransformerDifferentialRelays

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS

1. Introduction.

2. Protection Functions for Power Transformer.

3 Test Plan

3. Test Plan.

Doble International Protection Testing Users Group Conference Austin TX – Oct 13 – 14 2010

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS

1 Introduction

1. Introduction

.

F

l

d

th

t

ti

For

several

decades,

the

protection

relays of power system have undergone

many important changes

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS

ELECTRONIC RELAY ELECTROMECHANICAL

RELAY ELECTRONIC RELAY

RELAY

MICROPROCESSOR RELAYS

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS

1 Introduction

1. Introduction.

A modern transformer protection and control

system has many features that reflect the trends

of integration, such as:

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS

¾

Differential Protection for two or three winding

¾

Differential Protection for two or three winding

transformer.

¾

Second Harmonic Blocking

¾

Second Harmonic Blocking.

¾

Fifth Harmonic Blocking .

¾

_{Restricted Earth Fault Element.}

¾

Phase Overcurrent Protection.

¾

_{Ground Overcurrent Protection.}

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS

¾

Over/Under voltage Elements.

¾

Over/Under voltage Elements.

¾

_{Frequency Elements.}

¾

Thermal Element

¾

Thermal Element.

¾

_{Events recorder.}

¾

Fault recorder

¾

Fault recorder.

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS

The new protection features must be tested in

different system known conditions, which can

influence both its performance and safety.

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2. Protection Functions for Power

Transformer.

2.1 Transformer Differential Protection.

It is the most important transformer protection

function.

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2.1 Transformer Differential Protection

Idiff = I

₁

+ I

₂

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2.1 Transformer Differential Protection

The advantage of microprocessor technology is

g

p

gy

that

each

manufacturer

defines

their

own

algorithms, features and parameters to adjust

the differential function.

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2.1 Transformer Differential Protection

Setting:

1. Turn Point 1: Fixed 2 T P i t 2 V i bl

ABB RET543 RELAY

2. Turn Point 2: Variable 3. Slop 1: Variable

4. Slop 2: Fixed

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2.1 Transformer Differential Protection

Iop= I1 + I2

Irst= (|I1 | + |I2 |)/k

SEL RELAY

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2.1 Transformer Differential Protection

Another point to consider is the new option to filter

p

the zero sequence component of phase currents.

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2. Protection Functions for Power

Transformer.

2.2 Blocking Function

For harmonic blocking, the harmonic content of

the differential current must exceed the individual

threshold values

¾ Second Harmonic for inrush conditions

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2. Protection Functions for Power

Transformer.

2.3 Restricted Earth Fault Element.

This element provides sensitive protection against

ground

faults

in

wye-connected

transformer

winding

winding.

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2. Protection Functions for Power

Transformer.

2.4 Phase and Ground Overcurrent Protection.

IED

id

t l

t

IED provides numerous overcurrent elements

per winding.

Ph

d

ti

Phase,

ground

or

negative

sequence

instantaneous/definite

time

elements

are

available

for

single-

or

three-pole

feeder

available

for

single

or

three pole

feeder

protection,

breaker

failure

protection,

transformer backup protection, etc.

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2. Protection Functions for Power

Transformer.

2.5 Transformer

and

CT

connection

compensation

Transformer and CT connection compensation

adjusts the sets of three phase currents for the

adjusts the sets of three-phase currents for the

phase

angle

and

phase

interaction

effects

introduced by the winding connection of the

transformer and CTs.

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2. Protection Functions for Power

Transformer.

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2. Protection Functions for Power

Transformer.

2.5 Transformer and CT connection compensation

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2. Protection Functions for Power

Transformer.

2.5 Transformer and CT connection compensation

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3. Test Plan

3.1 Steady State Test

-

Pickup

of

differential,

overcurrent,

overvoltage or undervoltage functions.

-

Blocking functions

Differential Characteristic

-

Differential Characteristic

-

Overcurrent Characteristic

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3. Test Plan

Test set connection

CT1 I1 I2 RELÉ CT2 CT3 I2 I3 I4 CT4 CT5 I5 I6

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3. Test Plan

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3. Test Plan

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3. Test Plan

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3. Test Plan

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3. Test Plan

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3. Test Plan

0.522 * sqrt(3) = 0.904q ( )

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3. Test Plan

YY Transformer

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3. Test Plan

Iop= I1 + I2

Irst= (|I1 | + |I2 |)/k

SEL RELAY

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3. Test Plan

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3. Test Plan

DABY Transformer

ABC Rotation

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3. Test Plan

X

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3. Test Plan

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3. Test Plan

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3. Test Plan

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3. Test Plan

3.2 Dynamic Tests ( SSIMUL )

-

2 nd

and 5

th

Harmonic blocking function

-

Trip with 2

p

nd

and 5

th

Harmonic

-

Trip with 2

nd

Harmonic in one phase

No operation with 5

th

harmonic in one phase

-

No operation with 5

th

harmonic in one phase

-

External fault simulation

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3. Test Plan

3.2 Dynamic Tests ( SSIMUL )

Trip for 2nd Harmonic 3 Phase Test (PCT2 = 15%)

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3. Test Plan

3.2 Dynamic Tests ( SSIMUL )

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3. Test Plan

3.2 Dynamic Tests ( SSIMUL )

Internal Fault

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3. Test Plan

3.2 Dynamic Tests ( SSIMUL )

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3. Test Plan

3.2 Dynamic Tests ( SSIMUL )

External Fault

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3. Test Plan

3.2 Dynamic Tests ( SSIMUL )

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3. Test Plan

3.3 Transient Tests ( TRANS – COMTRADE

Files )

-

2 nd

and 5

th

Harmonic blocking function

d

h

-

Trip with 2

nd

and 5

th

Harmonic

-

Trip with 2

nd

Harmonic in one phase

-

No operation with 5

th

harmonic in one phase

External fault simulation

-

External fault simulation

-

Internal fault simulation

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3. Test Plan

3.3 Transient Tests

2nd Harmonic - DATC

3.3 Transient Tests

2nd Harmonic - DATC

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3. Test Plan

3.3 Transient Tests

2nd Harmonic – COMTRADE file

3.3 Transient Tests

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3. Test Plan

3.3 Transient Tests

Internal Fault – COMTRADE file

3.3 Transient Tests

Differential Sensibilization

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3. Test Plan

3.3 Transient Tests

Overexcitation – COMTRADE file

3.3 Transient Tests

ff Blocking Enable Differential Sensibilization

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS

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TESTING TRANSFORMER DIFFERENTIAL

RELAYS