04-shortcircuitcalculations

7/17/2019 04-shortcircuitcalculations

1/67

Copyright Siemens AG 2008. All rights reserved.

Short Circuit Calculation

Sector Energy

D SE PTI NC

Steffen Schmidt


2/67

Page 2 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt

Standards and Terms


3/67


Purpose of ShortCircuit Calculations

Dimensioning of switching deices

Dynamic dimensioning of switchgear

Therma! rating of e!ectrica! deices "e.g. ca#!es$

Protection coordination

%a&!t diagnostic

In'&t data for

Earthing st&dies

Interference ca!c&!ations E(C '!anning

)..


4/67

Page * 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt

ShortCircuit Calculation

Standards

IEC 60+0+,Short-Circ&it C&rrent Ca!c&!ation in Three-Phase .C. Systems

E&ro'ean Standard EN 60+0+ /erman Nationa! Standard DIN DE 0102 f&rther Nationa! Standards

Engineering ecommendation /* "45$Proced&re to (eet the e&irements of IEC 60+0+ for theCa!c&!ation of Short-Circ&it C&rrents in Three-Phase C Power

Systems

NSI IIEEE Std. C3.7 "4S$IEEE /&ide for Ca!c&!ation of %a&!t C&rrents for ''!ication of a.c. igho!tage Circ&it 9rea:ers ated on a Tota! C&rrent 9asis.


5/67


ShortCircuit Calculations

Standard !"C #0$0$

IEC 60+0+ , Short-circ&it c&rrents in three-'hase a.c. systems

Part 0, Ca!c&!ation of c&rrentsPart 1, %actors for the ca!c&!ation of

short-circ&it c&rrentsPart 2, E!ectrica! e&i'ment; data for

short-circ&it c&rrent ca!c&!ationsPart 3, C&rrents d&ring two se'arate

sim&!taneo&s !ine-to-earth shortcirc&its and 'artia! short-circ&itc&rrents f!owing thro&gh earth

Part *, E


6/67



Scope of !"C #0$0$

three-'hase a.c. systems !ow o!tage and high o!tage systems &' to 700 : nomina! fre&ency of 70 = and 60 = #a!anced and &n#a!anced short circ&its

three 'hase short circ&its two 'hase short circ&its "with and witho&t earth connection$ sing!e 'hase !ine-to-earth short circ&its in systems with so!id!y

earthed or im'edance earthed ne&tra! two se'arate sim&!taneo&s sing!e-'hase !ine-to-earth short circ&its

in a systems with iso!ated ne&tra! or a resonance earthed ne&tra!"IEC 60+0+-3$ ma


7/67Page 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt Copyright Siemens AG 200%. All rights reserved.


Types of Short Circuits

&phase

2phase

'phase


8/67Page + 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt


(arfromgenerator short circuit

I:> Initia! symmetrica! short-circ&it c&rrenti' Pea: short-circ&it c&rrentI: Steady-state short-circ&it c&rrent

Initia! a!&e of the d.c com'onent


9/67Page 10 28.06.2008 CopyrightSiemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt


)efinitions according !"C #0$0$ *!+

initial symmetrical shortcircuit current I,>r.m.s. a!&e of the a.c. symmetrica! com'onent of a 'ros'ectie"aai!a#!e$ short-circ&it c&rrent? a''!ica#!e at the instant of short circ&it ifthe im'edance remains at =ero-time a!&e

initial symmetrical shortcircuit po-er S,>fictitio&s a!&e determined as a 'rod&ct of the initia! symmetrica! short-circ&it c&rrent I:>? the nomina! system o!tage Unand the factor @3,

NATE, S:> is often &sed to ca!c&!ate the interna! im'edance of a networ: feeder at theconnection 'oint. In this case the definition gien sho&!d #e &sed in the fo!!owing form,

B:n

B: I43S =

B

:

2

n

S

4cC

=


10/67Page 11 28.06.2008 CopyrightSiemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt


)efinitions according !"C #0$0$ *!!+

decaying *aperiodic+ component id.c.of shortcircuit current

mean a!&e #etween the to' and #ottom ene!o'e of a short-circ&itc&rrent decaying from an initia! a!&e to =ero

pea, shortcircuit current ip

ma


11/67Page 12 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt


eartogenerator short circuit

I:> Initia! symmetrica! short-circ&it c&rrenti' Pea: short-circ&it c&rrentI: Steady-state short-circ&it c&rrent

Initia! a!&e of the d.c com'onentI9 Symmetrica! short-circ&it #rea:ing c&rrent

t/

9I22




)efinitions according !"C #0$0$ *!!!+

steadystate shortcircuit currentI,r.m.s. a!&e of the short-circ&it c&rrent which remains after the decay ofthe transient 'henomena

symmetrical shortcircuit rea,ing current I

r.m.s. a!&e of an integra! cyc!e of the symmetrica! a.c. com'onent of the'ros'ectie short-circ&it c&rrent at the instant of contact se'aration ofthe first 'o!e to o'en of a switching deice


13/67Page 1* 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt


Purpose of ShortCircuit 1alues

Design Criterion Physica! Effect e!eant short-circ&it c&rrent

9rea:ing ca'acity of circ&it

#rea:ers

Therma! stress to arcing

cham#er; arc e



Standard !"C #0$0$

Simplifications and Assumption

ss&m'tions &asi-static state instead of dynamic ca!c&!ation

no change in the ty'e of short circ&it d&ring fa&!t d&ration

no change in the networ: d&ring fa&!t d&ration

arc resistances are not ta:en into acco&nt im'edance of transformers is referred to ta' changer in main 'osition

neg!ecting of a!! sh&nt im'edances e



"uivalent 1oltage Source



Shortcircuit

"uivalent voltage source at the shortcircuit location

E

E CFCTC.

%

G

IB33

.n

Uc

rea! networ:

e&ia!ent circ&it

A'erationa! data and the 'assie !oad of cons&mers are neg!ectedTa'-changer 'osition of transformers is dis'ensa#!eE


17/67


Short circuit in meshed grid

"uivalent voltage source at the shortcircuit location

rea! networ: e&ia!ent circ&it


18/67

Page 1+ 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt

1oltage (actor c

c is a safety factorto consider the fo!!owing effects, o!tage ariations de'ending on time and '!ace? changing of transformer ta's? neg!ecting !oads and ca'acitances #y ca!c&!ations? the stransient #ehaio&r of generators and motors.

Nomina! o!tage

o!tage factor c for ca!c&!ation of

ma


19/67


4a5imum and minimum ShortCircuit Currents

ma


20/67


Short Circuit !mpedances and Correction (actors


21/67


Short Circuit !mpedances

%or networ: feeders? transformer? oerhead !ines? ca#!e etc.

im'edance of 'ositie se&ence system K im'edance of negatie se&ence system

im'edance of =ero se&ence system &s&a!!y different

to'o!ogy can #e different for =ero se&ence system

Correction factors for

generators? generator #!oc:s?

networ: transformer

factors are a!id in =ero? 'ositie? negatie se&ence system


22/67


et-or, feeders

t a feeder connection 'oint &s&a!!y one of the fo!!owing a!&es is gien, the initia! symmetrica! short circ&it c&rrent I:> the initia! short-circ&it 'ower S:>

If LM of the networ: feeder is &n:nown? one of the fo!!owing a!&es can#e &sed, LM K 0.1 LM K 0.0 for high o!tage systems 37 : fed #y oerhead !ines

B:

2n

B:

n

S

4c

I3

4c

C

=

=

2

EE

$ML"1

CM

+

=


23/67

Page 2* 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt

et-or, transformer

Correction of !mpedance

T5K T5T

genera!

at :nown conditions of o'eration

no correction for im'edances #etween star 'oint and gro&nd

T

ma


24/67


et-or, transformer

!mpact of Correction (actor

The Correction factor is 5T1.0 for transformers with


25/67


Generator -ith direct Connection to et-or,

Correction of !mpedance

/5K /5/

genera!

for contin&o&s o'eration a#oe rated o!tage,

4r/"1O'/$ instead of 4r/

t&r#ine generator, M"2$ K M"1$

sa!ient 'o!e generator, M"2$ K 1L2 "MdBO MB$

r/d

manearW or WfarW from generator

Definition short circ&it >nearW to generator

for at !east one synchrono&s machine is, I:> 2 X Ir?/eneratoror I:>with motor 1.07 X I:>witho&t motor

9rea:ing c&rrent I#for short circ&it WfarW from generator

I#K I:>


56/67


/rea,ing Current

Calculation in nonmeshed et-or,s

The #rea:ing c&rrent I9at a short-circ&it !ocation? fed from so&rces whichare not meshed is the s&m of the 'artia! short-circ&it c&rrents,


57/67


/rea,ing current

)ecay of Current fed from Generators

I9K Y X IW:

%actor Y to consider the decay of short circ&it c&rrent fed fromgenerators.


58/67


/rea,ing current

)ecay of Current fed from Asynchronous 4otors

I9K Y X X IW:

%actor to consider the decay of short circ&it c&rrent fed fromasynchrono&s motors.


59/67

Page 6* 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt

/rea,ing Current

Calculation in meshed et-or,s

Sim'!ified ca!c&!ation,

I#K I:>

%or increased acc&racy can #e &sed,

MWdi5 stransient reactance of the synchrono&s machine "i$MW(V reactance of the asynchrono&s motors "V$IW:/i ? IW:(V contri#&tion to initia! symmetrica! short-circ&it c&rrent from the synchrono&s machines "i$

and the asynchrono&s motors "V$ as meas&red at the machine termina!s

B

:(VVVV n

(VB

:/iii n

/iB

:# I$1"3L4c

B4I$1"

3L4c

B4II

=

B

:/iB

di5

B

/i IVM4 =B:(V

B(V

B(V IVM4 =


60/67


Continuous short circuit current

Contin&o&s short circ&it c&rrent I:

r.m.s. a!&e of short circ&it c&rrent after decay of a!! transienteffects

de'ending on ty'e and e


61/67


Shortcircuit -ith preload


62/67



Principle

Foad f!ow ca!c&!ation that considers a!! networ: 'arameters?s&ch as !oads? ta' 'ositions? etc.

9 P!ace o!tage so&rce with the o!tage that was determined #y

the !oad f!ow ca!c&!ation at the fa&!t !ocation.

C S&'er'osition of and 9


63/67



"5ample

Foad f!ow ca!c&!ation

9 Short circ&it ca!c&!ation

S


64/67

Page 6+ 28.06.2008 Copyright Siemens AG 2008. All rights reserved.E D SE PTI NCSteffen Schmidt


7esults

203367+2.11

1000

1+2.01681+.3203.+7


G G

367.3

20

-0

2000

-36*

336

+00.

-30.8+

7+2.11

1000

-0

1000

10

182

1+2

*0

208

168

*0.

17.3

1+.3

70.

173.+7

203.+7

Superposition< 9oad flo- = feed 0ac,

G G

367.3

2*6.78

201000

*0*070

9oad flo-

G G

7010

2 3 2 10 2

1*80+00

+000

00208.0

367.3173.+7

Shortcircuit< feed 0ac,

263.*2

182

8030.8+ 36*

17.3


66/67


Contact

Steffen SchmidtSenior Cons&!tantSiemens /? Energy SectorE D SE PTI NC

%reyes!e#enstr. 1+1078 Er!angen

Phone, O*+ +131 - 326*%a


67/67

Than, you for your attention>

Documents

04-shortcircuitcalculations