Stevenson J. Power system analysis

596

ER 14 Zb . METHODS IN CONTINGENCY ANALYSIS

In this equation we have shown only those elements of Ac and Z

which

ntribute to the calculation. Since all the other elements of A

are zeros, it is

not

necessary to display the full

. The indicated multiplications yield

a [

(

m -

Z",") -

(ZlIm -

ZIIII)

cZbusA�

(Z"m - Z") - (

'IIII -

II")

(14 .12)

The diagon al clements in this equation can be recognized from Fig. 1

.3 as the

Thevenin impedances Z'

1."," and Z'h.!)

seen when looking into the original

system between buses @-@ and ®-, respectively. That is,

(14.13)

Substituting from Eq. (14.12) into Eq. (14.9), we obtain

(14.14)

which shows that the compensating currents I

and Ih can be calculated by

using the known bus voltages