Page 106 - Power Quality in Electrical Systems

Power Harmonic Filters 89

Ls PCC
100 uH I L 1 5 1 7
v s + j(37.7 mΩ) + + + −
−
−
−
277 V 100 A 20 A 15 A
(a)

120 A
80 A

40 A

0 A
−40 A

−80 A

−120 A
10 s 10 ms 20 ms 30 ms 40 ms 50 ms 60 ms 70 ms 80 ms 90 ms 100 ms
I(Ls) Time
(b)

120 A

100 A
80 A

60 A

40 A
20 A

0 A
0Hz 0.1KHz 0.2KHz 0.3KHz 0.4KHz 0.5KHz 0.6KHz 0.7KHz 0.8KHz 0.9KHz 1.0KHz
I(Ls) Frequency
(c)
Figure 6.16 The circuit for Example 6.2. (a) The circuit. (b) The line current. (c) The spec-
trum of the line current.

First, we need to determine what the IEEE-519 limits are for line har-
monic currents, using Table 10.3 (Figure 6.5). Note that the harmonic
current limits depend on the ratio I /I , where I SC is the short-circuit
L
SC
current at the PCC, and I 100 A is the fundamental load current. For
L