presentation p631+p632+p633+p634

MiCOM P631…634Transformer Differential Protection

October 2005

Rudolf SimonDr.-Ing.

> MiCOM P630C/P631...634 Transformer Differential Protection - March 2004 - P63x Presentation EN f+3 3


Applications

Two Winding Transformers

Unit TransformersThree Winding Transformers

Reactors

Generators

Ring Bus Fed Windings

Auto Transformers

Motors


ANSI No. P631 P632 P633 P634

Differential protection 87 2 wind. 2 wind. 3 wind. 4 wind.

Restricted earth fault prot. 87G – 2 3 3

Definite-time O/C protection 50 2 2 3 3

Inverse-time O/C protection 51 2 2 3 3

Thermal overload protection 49 1 1 2 2

Over/undervoltage protection 27, 59 – 1 1 1

Over/underfrequency prot. 81 – 1 1 1

Overexcitation protection 24 – 1 1 1

Current transformer monitor. option option option option

Measuring circuit monitoring 2 2 3 4

CB Failure Protection 50BF 2 2 3 4

Limit value monitoring 2 2 3 3

Programmable logic 1 1 1 1


Main Functions

P630C is functionally equivalent to P631.



Inputs and Outputs

P631 P632 P633 P634

Measuring inputs

Phase currents 2 x 3 2 x 3 3 x 3 4 x 3

Residual current or star-point current – 2 3 3

Voltage – 1 1 1

Binary inputs and outputs

Optical coupler inputs (per order) 4 4 to 10 4 to 16 4 to 10

Add. optical coupler inputs (optional) – 24 24 24

Output relays (per order) 8 to 14 8 to 22 8 to 30 8 to 22

Analogue inputs and outputs (optional)

0 to 20 mA input – 1 1 1

PT 100 input – 1 1 1

0 to 20 mA outputs – 2 2 2



Screw Terminals for Pin Lugs

Screw Terminals for Ring Lugs

Models

GGC

GG

G

G

G

TR IP

A LA R M

O U T O F S E R V IC E

H E A LTH Y

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

GGC

GG

G

G

G

TR IP

A LA R M


H E A LTH Y

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

GGC

GG

G

G

G

TR IP

A LA R M


H E A LTH Y

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

GGC

GG

G

TR IP

A LA R M


H E A LTH Y

G

G

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

GGC

GG

G

TR IP

A LA R M


H E A LTH Y

G

G

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

GGC

GG

G

G

G

TR IP

A LA R M


H E A LTH Y

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

GGC

GG

G

G

G

TR IP

ALAR M

O U T O F SER VIC E

H EALTH Y

ED IT

= C LEAR

= EN TER

= R EAD

C

MiCOM

GGC

GG

G

TR IP

A LA R M


H E A LTH Y

G

G

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

P631

GGC

GG

G

TR IP

A LA R M


H E A LTH Y

G

G

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

P632 P633 P634


Functional Details



MiCOM P631…634Functional Details

DIFF

Differential Protection


MiCOM P631…634Differential Protection

Main Features

GGC

GG

G

TR IP

ALAR M

O U T O F SER VIC E

H EALTH Y

G

G

ED IT

= C LEAR

= EN TER

= R EAD

C

MiCOM

GGC

GG

G

G

G

TR IP

A LA R M


H E A LTH Y

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

GGC

GG

G

G

G

TR IP

A LA R M


H E A LTH Y

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

P631 P632 P633 P634

GGC

GG

G

TR IP

A LA R M


H E A LTH Y

G

G

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

GGC

GG

G

TR IP

A LA R M


H E A LTH Y

G

G

E D IT

= C LE A R

= E N TE R

= R E A D

C

MiCOM

3-system differential protection for transformers, generators and motors 2, 3 or 4 bias inputs per phase Amplitude and vector group matching Zero sequence current filtering for each winding Triple-slope tripping characteristic Unrestrained instanteneous differential element Magnetizing inrush stabilization (second harmonic), with/without cross-blocking Overflux blocking (fifth harmonic) Through-fault stability with c.t. saturation detection



Amplitude Matching

A

B

CW ind ing a

Inom, C T, prim , a V nom, prim , a V nom, prim , b

Sref, prim = Snom, prim , max

Inom, C T, prim , b

A

B

C

W ind ing b

All you have to do: Simply set these nominal values!



Vector Group Matching

A

B

CW inding a

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11

A

B

C

W inding b

All you have to do: Simply set the vector group ID!



Zero Sequence Current Filtering

A

B

C

W inding a

w ith I0 filtering w ithout I0 filtering

A

B

C

W inding b

All you have to do: Simply set ‘with‘ or ‘without‘!



Tripping Characteristic

Basic threshould value Id>, slope m1, second knee point IR,m2 and slope m2 are settable.

1 2 3 4

1

2

0

Id

IR

Load linefor s ing le-end in feed

Id>

m 1

m 2

IR ,m 2


REF_1 REF_2 REF_3


Restricted Earth Fault Protection


MiCOM P631…634Restricted Earth Fault Protection

DIFF REF: In-Zone Fault on Transformer Yyn(d)

A

B

C

{IA, IB, IC}

A

B

C

N a Nb

0 ... f ... 1

Id,G>IY

Ix,aId>

Ix,b

: 1N

N withand

IfN

Nf

3

2=I

N

Nf

3

2=I

b

a

maxG,a

bY

a

baA,

maxG,YG,d If=I=I maxG,

2aA,d If

3

2=II


1

f0

0.2 0.55

0.2

0.660.57

Id,G/IG,max

Id/IG,max

0.59 10


DIFF REF: Comparison of Sensitivity

maxG,G,d If=I

maxG,2

d If3

1I

maxG,2

d If3

2I

The advantage of ground differential protection resides in the linear dependency of the sensitivity on fault location.



Operating Modes

Low impedance principle:

Biasing by residual current

Low impedance principle:

Biasing by maximum phase current

High impedance principle



Tripping Characteristic: Biasing by Residual Current

Id,G>

Id,G /Iref

m = 1.005

1 1.5 20.5

0.5

1

1.5

IR ,G /Iref

C haracteristic forline side feed only (IY=0)

2

Definition of Id,G and IR,G:

CBAP,ampG,R

YY,ampCBAP,ampG,d

I,I,IkI

IkI,I,IkI



Tripping Characteristic: Biasing by Maximum Phase Current

Id,G>

Id,G /Iref

m 2

1 1.5 20.5

0.5

1

1.5

IR ,G /Iref

2

m 1

IR ,G ,m 2

C haracteristic forline side feed only (IY=0)

Definition of Id,G and IR,G:

YY,ampCBAP,ampG,R

YY,ampCBAP,ampG,d

IkI,I,Imaxk2

1I

IkI,I,IkI



High Impedance Principle

A

B

C

R L,PR L,P

R C T ,P

R L,Y

R L,Y

R stab

R C T ,Y

saturated C T

Id,G>

Voltage across the stabilizing resistor: P,LP,CTmax,ext,scmax,ext,sc R2RIV


0

0,005

0,01

0,015

0,02

0,025

0,03

0,035

0,04

0,045

0 5 10 15 20

Vknee/Vstab

t/[s]


High Impedance: Operating Time

Ratio Vknee/Vstab > 2 ensures tripping times of less than 2 cycles.



DTOC1 DTOC2 DTOC3

Definite-Time Overcurrent Protection


Definite-time overcurrent protection, three-stage, phase-selective Each function group (DTOC1, DTOC2, DTOC3) is freely assignable

to a winding Virtual winding may be defined for summation of currents from two real

windings (two breakers in a ring bus or breaker-and-a-half configuration) 3 separate measuring systems for

phase currents, negative-sequence current and residual current

All 3 measuring systems operate independently of each other: Operate value of the stage may be set as a dynamic parameter Settable operate delay per stage Sequence of all operate delays can be blocked

– through appropriately configured binary signal inputs or

– per selection matrix via a binary signal input or

– per programmable logic (LOGIC)

MiCOM P631…634Definite-Time O/C Protection

Main Features



IDMT1 IDMT2 IDMT3

Inverse-Time Overcurrent Protection


Inverse-time overcurrent protection, single-stage, phase-selective Each function group (IDMT1, IDMT2, IDMT3) is freely assignable

to a winding Virtual winding may be defined for summation of currents from two real

windings (two breakers in a ring bus or breaker-and-a-half configuration) 3 separate measuring systems for phase currents, negative-sequence

current and residual current

All 3 measuring systems operate independently of each other: Operate value of the stage may be set as a dynamic parameter Choice of 12 different tripping time characteristics Accumulation of intermittend startings by means of a hold-time logic Sequence of all operate delays can be blocked




MiCOM P631…634Inverse-Time O/C Protection

Main Features


1

10

1 10 100I/Iref

t/[s]

0,1

1

10

100

1 10 100I/Iref

t/[s]


Tripping Characteristics acc. to IEC and ASEA

NI

LTI

VI

EI

RI

RXIDG

NI: Normally inverseVI: Very inverseEI: Extremely inverseLTI: Long time inverse

RI: RI-type inverseRXIDG: RXIDG-type inverse


0,1

1

10

100

0,1 1 10 100I/Iref

t/[s]

0,01

0,1

1

10

100

0,1 1 10 100I/Iref

t/[s]


Tripping Characteristics acc. to ANSI/IEEE

EI

VI

MI

EI

VI

MI

LTI

NI

STI

LTI

NI

STI

MI: Moderately inverseVI: Very inverseEI: Extremely inverse

NI: Normally inverseSTI: Short time inverseLTI: Long time inverse



THRM1 THRM2

Thermal Overload Protection


MiCOM P631…634Thermal Overload Protection

First-Order Model Based on IEC 60255-8

a

I2

(t)

ka

wThermal

conductance

Specificthermal capacity

Square of current

Protected objectTemperature (t)

CoolantTemperature a

Proportionalityfactor

In thermal overload protection based on IEC 60255-8, a simple homogeneous two-body model

(protected object and coolant) is considered.



Model Equation

t

(t)

a

0

aa2I

k

a Ultimate temperature

Ultimate temperature rise

Transition from the initial temperatur 0 to the final temperatur (ultimate temperatur)

based on the rise time constant at constant current I.



Consideration of the Coolant Temperature

max,amax

max,aatrip

t

0

2

ref0 e1

I

It

tI offset

The offset offset corrects the state of the thermal replica for the normal case in which the actual coolant

temperature a is not equal to the maximum coolant temperature a,max.



Graphic Representation of the Offset

trip

offset

100 %

0 %a,m ax m ax a

The offset offset disappears at a = a,max .



V<>

Over-/Undervoltage Protection


Definite-time overvoltage protection, two-stage

Definite-time undervoltage protection, two-stage:

– Transient signals are provided to be included in trip command

– Window function is provided for each timer stage

Reset ratio (hysteresis) settable

Sequence of all operate delays can be blocked




MiCOM P631…634Over-/Undervoltage Protection

Main Features



f<>

Over-/Underfrequency Protection


Over-/underfrequncy protection, four-stage

All four stages operate independently of each other: Operation modes:

– Over-/underfrequency monitoring

– Over-/underfrequency monitoring in conjunction with differential frequency gradient monitoring (df/dt) for system decoupling applications

– Over-/underfrequency monitoring in conjunction with average frequency gradient monitoring (f/t) for load shedding applications

Settable operate delay Sequence of all operate delays can be blocked




MiCOM P631…634Over-/Underfrequency Protection

Main Features


f

fx

fnomt

tx


Time Delayed Over-/Underfrequeny

Start

Trip


f

fx

fnomt

tx

dfx/d t


Time Delayed ROCOF

Trip

Start


f

fx

fnomt

fx

tx


Average ROCOF

Trip

Start



V/f

Overexcitation Protection


V/f ratio based measurement

Alarm stage V/f> with definite time delay

Trip stage V/f>> with inverse time characteristic

– Characteristic defined by 12 settable value pairs

– Cooling time of thermal replica settable

Trip stage V/f>>> with definite time delay

Sequence of all operate delays can be blocked




MiCOM P631…634Overexcitation Protection

Main Features

Reset ratio 0,98


MiCOM P631…634Overexcitation Protection

Tripping Characteristic

...

V /f

t

1.00 1.10 1.20 1.30 1.40 1.50 1.60

V nom /fnom

1

10

100

V/f>>>

V/f>>

...



CBF

CB Failure Protection


MiCOM P631…634CB Failure Protection

Overview

Common Px3x platform function – see platform presentation for more details!

Monitoring of settable undercurrent condition, phase-selective 2 timer stages to allow retripping and backup-tripping Independent trip commands, incl. lock-out function Additional monitoring of CB aux. contacts (52a, 52b) as CB fail criterion

in case of „trip w/o current“ Plausibility check of CB position signals Pole Discrepancy Supervision „Starting triggering“ to provide back-up protection

in case of downstream CB failure condition Stub bus / end-zone protection



CTS

CT Supervision


MiCOM P631…634CT Supervision

A Universal CTS function

suitable for ALL MiCOM Devices

Universal scheme suitable for all differential devices

Suitable for implementation on any MiCOM relay

No reference to VT ’s required

Suitable for blocking or indications as required by the user

Requirements


Ratio of Negative to Positive sequence current is measured at each CT set

If ratio is zero (or small) either unloaded, balanced load, three phase fault or three phase CT problem

If ratio is non-zero, either asymmetric fault or CT problem

Ratio calculated at all CT ends

If ratio is non-zero at two (or more ends) simultaneously, it is almost certainly a genuine fault condition & unlikely to be a CT problem


Principles (1)


Ratio of Negative to Positive sequence current cannot distinguish between genuine faults and CT problems

Additional criteria is positive sequence (load) current, I1

Better detection criteria than phase currents

Considering a situation where the ratio is non-zero at one end only

If I1 only detected at one end, system is unloaded and therefore calculated non-zero ratio is due to a single-end fed fault or inrush condition

If I1 detected at two (or more) ends, this is a CT problem or sympathetic inrush on parallel transformers


Principles (2)


> 2

&

> 1

> 1

= 1

=(N-1)

CTS: Operated

DIFF: Any blocking

CTS: Blocking EXT

MAIN: Gen. trip signal

I2/I1 end a

> I1> (e.g. 10%)

I1 end aI1 end bI1 end cI1 end d

< I2/I1> (e.g. 5%)

I2/I1 end b

I2/I1 end c

I2/I1 end d

> I2/I1>> (e.g. 40%)

> 1

> 1

&CTS: End a flt.


Operating condition


CTS: Operated (updating)

CTS: Idiff>(CTS) activ.

CTS: Operated (latched)

> 1

S

R

Q

t Alarm 0

CTS: Operated

MAIN: General Reset

CTS: Reset latching> 1

CTS: Alarm end a (updat.)

CTS: Alarm end a

CTS: Alarm end a (latch.)

CTS: End a flt.

overall signals

per end signals

t Latch 0

> 1

S

R

Q

t Alarm 0

t Latch 0


Signaling


CTS impact on DIFF depends on setting:

Alarm Mode: Idiff> (CTS) = Idiff> (= Indication only)

Restrain Mode: Idiff> (CTS) > max. phase load current

Blocking Mode: Idiff> (CTS) Idiff>>


Characteristic shift

1 2 3

1

0

Idiff

IR

Load linefor single side infeed

Idiff>

IR,m2

m1

m2

Idiff>(CTS)

2

No Trip

Trip



MCM_1

Measuring Circuit Monitoring

MCM_4MCM_3

MCM_2


Sequence current ratio based measurement per end

Alarm or Trip stage I2/I1> with definite time delay

Function too slow for blocking DIFF CTS required for this application

Function can be used as ‘Broken Conductor’ protection

Function can be blocked




MiCOM P631…634Measuring Circuit Monitoring

Main Features



LIMIT

Limit Value Monitoring


MiCOM P631…634Limit Value Monitoring

Functionality

0 1

t>>

0 1

t>>>>

0 1

t<<

0 1

t<<<<

Measurands:

Phase currentsTemperature20 mA DC curr. ...

Signals:

Starting >t> elapsed ...

Intended to use for monitoring applications only!



LOGIC

Programmable Logic


MiCOM P631…634Programmable Logic

Embedding of Programmable Logic

Configuration:

INPLOCPC

COMM1COMM2

Fixed Logic:

DIST, IDMT, DIFF, ...Configuration:

OUTPLEDLOCPC

COMM1COMM2

Control Inputs

Trip and Signals

Functions


MiCOM P631…634Programmable Logic

Embedding of Programmable Logic

Programmable Logic:

LOGIC

Configuration:

INPLOCPC

COMM1COMM2

Fixed Logic:

DIST, IDMT, DIFF, ...Configuration:

OUTPLEDLOCPC

COMM1COMM2

Control Inputs

Trip and Signals

Functions

presentation p631+p632+p633+p634

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