Electric Power Generation, Transmission, and Distribution

IS¼

kVAbase

ffiffiffi

3

p

kVLLsource

(21:150)

ZS¼

kVLL^2 source 1000

kVAB

(21:151)

.The load side base values are computed by

kVLNL¼

kVLNS

ax

(21:152)

IL¼axIS (21:153)

ZL¼

ZS

ax^2

(21:154)

The matrices [at], [bt], [ct], [dt], [At], and [Bt] [see Eqs. (21.136)through(21.138)] for each connection
are defined as follows:

21.1.5.4 Matrix Definitions

21.1.5.4.1 Delta–Grounded Wye

Backward sweep:

½Š¼VLNABC ½Šat½ŠþVLGabc ½Šbt½ŠIabc

½Š¼IABC ½Šct½ŠþVLGabc ½Šdt½ŠIabc

Forward sweep:

½Š¼VLGabc ½ŠAt½ŠVLNABC ½ŠBt½ŠIabc

The matrices used for the step-down connection are

½Š¼at

nt

3

021

102

210

2

6

4

3

7

5

½Š¼bt

nt

3

02 Ztb Ztc

Zta 02 Ztc

2 Zta Ztb 0

2

6

4

3

7

5

½Š¼ct

000

000

000

2

6

4

3

7

5

½Š¼dt

1

nt

1  10

01  1

 101

2

6

4

3

7

5