Training SAS, Protections

Technology that moves the world

Power Systems Automation

2

3

!"#$ % & (

!

Only depends on the current, based on the simple fact which is: if there is a default, the current rises.

The most common protection function in MV or radial networks. Used also as a backup protection.

Pros

Only depends on the current (except directional functions) Simple to configure and test (few parameters) Simple to coordinate in radial networks

Cons

Trip times can be long to ensure selectivity Dont guarantee selectivity on non radial networks (meshed or rings) Sensitivity problems to detect high resistance fault

4

"

This function allows the correct discrimination of faults in the direction of the protected line from the external faults in the other direction, using the phase information of the zero sequence short-circuit current.

This fault occurs when there is a current that closes itself by the lines capacitances when occurring a short-circuit to earth in some point of the network.

5

#$%&

In a healthy line, the residual current is in quadrature and in advance towards the residual voltage (capacitive current).In the faulty line, the phase ratio depends on the way neutral is connected to

earth:

6

For isolated neutral systems, the residual current on the faulty line is in quadrature but delayed towards the residual voltage, the residual reactive power sign can be used to describe the fault location;

For compensated neutral systems, the fault can be detected by the presence of an active component on the residual power

The previous criterion can also be applied to neutral systems with limitation impedance, since it has a minimum of resistive component.

#$%&

Relay non-operation zone

Used: In distribution or radial networks (feeders, incoming) As backup, in all panels (integrated in multifunctional

equipment) In capacitor banks

Examples of equipment: EFACEC: TPU S100, TPU S420 SIEMENS: 7SJ6xx ABB: REF, SPAJ 140 SEL: SEL 451

7

$

8

#

()*+

Zline = 10

Zd < 10

Zd > 10

2nd step (or zone) timed to coordinate with downstream protections (typical 0,5 s)

1st step (or zone), with instantaneous trip

3rd step (or zone) backup, with long temporization (typical 1s)

Pros

Suitable for meshed networks Short trip times in the 1st and 2nd zone Easy to coordinate Selectivity and actuation speed improved with teleprotection scheme Allows multiple network backups Suitable for long lines

Cons

Very dependent on protected line or equipment data Complex to set (too many settings) Depends on the voltage (needs overcurrent backup) Selectivity problems for short lines (mainly if there is no teleprotection

scheme)

9

#

)*+ ,

-,, !

+,, % -! %

#$!#. * * $% /0! ,,

,% -, 0

,,( !,+,%

#, ),, +

+0+

10

#%

Used in: Lines and cables VHV, HV and MV of meshed or ring

networks

Examples of equipment: EFACEC: TPU L420; TPU L500 SIEMENS: 7SA612, 7SA522 ABB: REL 670, REL 511, REL 521 SEL: SEL 421

11

$

Pros

,+ 1 , #

Cons

!%! % ,0!0 %

12

Line Differential Protection

Used in:

Can be used in any type of line or cable, but is more usual in HV and VHV

Examples of equipment:

EFACEC: TPU D500

SIEMENS: 7SD523, 7SD610

ABB: RED 670

SEL: SEL 311L

13

$

14

Direct fibber, typical distances: Multimode: up to 3,5 Km Singlemode: up to 80 Km (can have different transceivers)

Convertor (eg 7XV5662) Optical Fibber Convertor to G703 or X21

Pilot wire (no longer used)

1 OR 2 INTERFACES

,#!!+!

15

+!-.

16

Pros

,+ 1 ,

Cons

1,

2,

,0!0 %

!#!!

Used in: Transformers, very short lines and simple busbar

Examples of equipment: EFACEC: TPU TD420, TPU T500 SIEMENS: 7UT633 ABB: RET 670 SEL: SEL 487, SEL 387

17

$

18

/

3 winding Transformer

Generator

Simple busbar protection with phase-selective

configuration

With several measure points

Basic principle of Kirchoff law: the sum of all currents on the bus must be null.

Pros

,+ 1 , +

Cons

, ) 0 ,3 ,

,,

19

- #!!

20

50

terminal panel

substation

50

terminal panel

50

terminal panel

50

terminal panel50

50 50

50

Centralized Solution

50

terminal panel

50

terminal panel

50

terminal panel

50

terminal panel

.

substationcentral unit

fibre optics2

2 221,5 km

bay unit

Distributed Solution

0

21

/1 #-

/1

$0-.%-

% !%-%%

0-- %--

20!+*"%-

#-

%-0%

#3-0%4-0%-0

0 % !-5

%%+*"

"0%%.3

+4

22

$

/1

2$6 2$78 $,9:8 $,6:8;

#-

86486 ? / 86@ ?

2$6

$&/$/ . % -- !! % 6 ; 6>5 % - ! 0

Protections related functions

Auto reclosing Voltage and frequency sheding and restoration Circuit Breaker failure Reverse Interlocking Trip transfer

23

Main purpose is the service restoration of the line after the clearance of temporary or intermittent faults, common in aerial networks.

Consistes in: disconnection of a line after fault detection for a specified time. followed by the reclosing command based on the probability that the fault was

cleared in the meantime. if the fault is cleared, there is a blocking time fault in order to confirm the

absence of fault.

If the fault remains, after all reclosing cycles definitive trip is signalized. Each one of these cycles can still be configured according with two pre-defined types, namely fast cycles and slow cycles.

24

2

Intended for transient fault situations with very low clearance time. When in a fast cycle phase, the Reclosing function working makes an instantaneous disconnection followed by the restoration command.

The circuit-breaker command, given by the Automatic Reclosing, is generated after any pickup of the Overcurrent Protection functions, without expecting its trip.

Fast cycles may imply a slight delay in the trip command, in order to avoid reconnections caused by very fast disturbances that do not provoke trip, but only the protection functions pickup.

25

2= &/0

Protcion Pick-up

Open cmd

Close cmd

Protection Pick-up

Ttrip Tisol Treclaim

In the slow cycles the protection functions give the opening command of the circuit-breaker, and the Automatic Reclosing is responsible by its restoration.

The slow reclosing is intended to clear faults with bigger extinction time, as the case of an earth short-circuit through a tree.

26

2= ./0

TisolTtrip Treclaim

Top

Tisol_l

Protection Pick-up

Open cmd

Close cmd

The main purpose of this function is the disconnection after a voltage drop and the after its regularization an automatic reclosing

This function is made independently in each one of the output substation protections. To make a sequential restoration of all loads it is necessary to properly scale the stable voltage confirmation time of each one of the protections inserted in the restoration cycle

The voltage measure (VT) has to be upstream If a circuit breaker was open before the fault this bay remains open.

27/25

2

28

&02

The frequency instability is basically due to differences between the generated and consumed power on the system

The main goal of this function is the very fast loads shedding caused by a frequency drop and an automatic reclosing after the frequency restoration or after a remote order (by dispatch center, for example)

This function is independently made in each one of the substation outputs protections. In order to do the load sequential restoration, as shown on the Voltage Restoration, it is necessary to stage the constant frequency confirmation time or after the remote order

4 56 , ,!% !%

7 +

0

29

/=-3!

The Reverse Interlocking intends to accelerate the unit trip that protects the bus-bar, through the interaction of the downstream protections.

Only applicable in radial networks, when the energy flows only by one direction

30

2+3

The operational time of the bus-bar high threshold can be effectively reduced, and it is enough to engage a security margin sufficient to receive the indicationNotice: substations with 2 or more depending on the position of the bus coupler, the blocking signal should arrive at all the connected incomings.

If the fault is on the busbar, only the incoming protection will see it, eliminating it after that short timer.

Protection Pick-up

If the fault occurs on an feeder, the corresponding protection will pickup and block immediately the upstream protection trip.

Protection process interfaceElectrical wiring

Substations topologies Circuit breaker Isolators CTs and VTs Teleprotetion and intertrip

Close order permission by protections OK Trip circuit supervision Auxiliary relays

31

)&)#-4

&,,

,+ ,!1%

7+ 0

!+% +

++8 + +,

47&)#-4

#+ 9

32

+"A"","+$0

*,* !1:10%

#,* 7,*+

+ *

7*0,,!%

#$

33

/=-3+!

7+ *00 970

34

++!

$ + + ; + % %

Isolator

OpenClosed

Open

Closed

Mains Contacts

closing closingOpen

-0 !,7=1-%

0(!?2 %

(*,

10

0 !@%, +

35

/ %

+:1

36

:10

7+0$ ! %

#2 !560 ,*0%

)*+ 0

37

+

3 *0 A

A

A *,9 + *0 + , 999

7 + 7 A 9

38

! "B

! ""!

,,09$+>==BCD>-!?==1%90,2=1-CD=+>-9

7,,

);4# 0

/# 7

0,;4E:2

;4E#? 39

40 20

#

$

%

&

%

%$

"$

(

)

*+*,

)-

-.+*,

/"0,"$+1""

+"

),*0>,

4#

*0!% )

/#

!%

7,

;4E

40

40 20

#

$

%

&

%

%$

"

(

(

)

*+,

2"3+" .

41

4020+ /%

Fast relay

Fast, but no cut off power!!

Cut off power

Making capacity

Needs contact in serie to souble the cut off

power

09

-+0

+,0+,,

220F+,,,!??=1%

!,#4-%

42

%

#

$

%

&

%

%$

"

(

(

("

!,.++"

"!"

1!

4*!+5

"

4

6++7+"

+$"*!$18+1