Hardware and Functional Development of Protection Devices and Systems - Digital Signal Processing in Power System Protection and Control - page 20

Fig. 3.7 Frequency response of the 1st order RC filter

Fig. 3.8 Frequency response of the 3rd order RC filter

þ X

p

Þ þ I a exp s
T a

i ðÞ¼ I 1m cos x 1 s a 1

ð

I km cos kx 1 s a k

ð Þ

k ¼ 2

cos x h s b h

þ X

r

I hm exp s
T h

ð Þ : ð 3 : 5 Þ

h ¼ 1