POWER SYSTEM ANALYSIS

TADP 641

Case Example

SHORT CIRCUIT

CALCULATION

Juan Manuel Gers, PhD

Example

Example

Calculate the short circuit current for a three phase fault at busbar D.

Consider that the Hydro Power Station is under maintenance and therefore all the breakers associated are open.

Let base MVA = 75 MVA

Let base kV on 132 kV nominal part of system = 132 kV

The base kV on other parts of the system is obtained by referring this voltage through the interconnecting transformers.

Example Solution

SUPPLYGRID

G3

G4

G5

G6

E'

T9

T10

T17

T18

T16

T15

E

D6

T20

T21

T13T11

D4B

D4A

T12

F'

F

D5

DT7

T8

D'

D2

C C'

Positive Secuence Diagram for Fault at Busbar D

NEUTRAL BUS ' N '

E

G6

G5

G4

G3

T18

T17

T16

T15

FI

F

D5

D4B

D4A

D6

E

T10

T9

E'

SZ

D

Positive Sequence Network

P.U.1E

FI

EE'

Z

F

E

I

AZ

D

ZB

FI

E

A

D

ZC

Equivalent Impedances

The resulting positive sequence diagram is shown below:

..0712.04

285.0

4

151.0134.0upZ A

..0897.00327.0047.001.01768.0

1335.00433.0

2

094.001.0 up

xZ B

..0397.01607.0

0897.00712.0upZC

..19.250397.0

1up

Z

EI

c

F

Axx

xupcurrentBase 328

101323

1075.).1(

3

6

Fault Current Calculation

Solution of Example with Software

Questions?