Protection General

EV SProtection and Substation Control

Datum 09/97Bearbeiter f. meisbergerDateinamel Landau.pptSeite 1 von 14

Your Partner for Protection Systems

Protection Technology




The Purpose of Protection

but it can:Limit the damage caused by

short circuits

while: Protecting people and plant from

damage

Selectively clearing faults in miliseconds

Protecting plant from overload conditions

The protection can not prevent system faults,




Tasks

Fast fast means, recognising and removing the fault in milliseconds

Safe safe means, always switching-off, when a fault appeares

Selectivity selectivity means, switching-off only the system elements,where the fault

had accoured.




History

1950 1960 1970 1980 1990 2000

MOVING-COIL TECHNOLOGYANALOG TECHNOLOGY

DIGITAL TECHNOLOGY




Why digital Protection?

Integration of the Protection functions for one feeder:

Feeder Protection Device

Example: Overhead line in medium voltage Distance Protection with I>> or U</I>-exitation

Three-pole reclosure

Wattmetric earth fault direction detection

Fault location

Event protocol

Fault recording





Self-supervision

Raising of the Availability

Plausibility control of the input values

Supervision of the A/D-Conversion

Internal Testing of the Computer systems (Watch-Dog)

Supervision of the memory chips

Testing the TRIP-Relay-coil




Self-supervision Plausibility test of the input values e.g.:

IL1+IL2+IL3=k1xIE

UL1+UL2+UL3=k2xUE

Rotating-field control of the measurements Control of the Analog-Digital-

Conversion by comparison with conversed reference values

Hard- and Software supervision of the Microprocessor systems

Supervision of the two-canaled command-Relay

Direction testing with operational-values, test-TRIP, test- TRIP/CLOSE (not automatic)

x

A D

uP





Higher Information offer

Transparence of the incident history

Event protocol and fault recording give break-down

What has happened ?

What are the short circuit values (Transformer saturation) ?

When did the protection gave his Off-command ?

How long time needed the circuit-breaker ?

How big was the breaking current ?

How did the Network recover after switching-off ?




Princip metod of operation

Analog input values

Analog-Digital-Conversion

Exitation

Protection programm Routine programm

Command- and Information outputs

yes no




Analog measurement-values forming

Analog: the stability limits will be formed by comparison with analog reference values. These reference values can change themselves by component drifts.(Ageing).

Possible changing of set-values (Ageing)

analog

1I1U

U2

U1<U2 no exitation

U1>U2 exitation




Digital measurement-values forming

Digital: the measurement value in one number will be conversed and with one number from the memory store compared.

Not possible changing of the set values (no Ageing)

digital

U1I1

A

D0 0 0 1 0 1 0 0 1 0 0 1

0 0 0 1 0 1 0 0 1 0 1 1

Mom.current 1,05A no exitationSet-value 1,10A

Mom.current 1,65A exitationSet-value 1,10A

Set values from EEprom




Analog Device design

All functions, like exitation or timeing, will be processed from discrete, permanent madnetised single elements. The results will be converted as electric values from other elements.

The General function is the summ of few single functions with permanent magnetised Hardware. By testing each single function must be tested.

I

U

LEDI>>

I>/U<

inputs

Zones

Timing

Direction

Trip/close

Alarm

Lo

gic

in

str

uc

t io

n




Digital Device design

All functions will be software moderated and processed on one hardware. With the results of the total operating time the output elements are directly controled.

The General function is the summ of the Software-single functions on one Hardware. Hard- and Software are supervisioned.

Port

Port

A

DI

U

Ari

thm

eti

c-l

og

ic u

nit

LED

.

Trip/close

Alarminputs

Single-board system




Protection System

The System is as strong as the weakest element!

Circuit breakerTransformer

Protection device Battery

Supply conducters

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Distance Protection

Protection General

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