Page 195 - Power Electronic Control in Electrical Systems

//SYS21/F:/PEC/REVISES_10-11-01/075065126-CH006.3D ± 183 ± [177±262/86] 17.11.2001 10:22AM

Power electronic control in electrical systems 183

Table 6.2 Maximum amplitudes of harmonic currents
in TCR a
Harmonic order Percentage

1 100.00
3 (13:78) b
5 5.05
7 2.59
9 (1.57)
11 1.05
13 0.75
15 (0.57)
17 0.44
19 0.35
21 (0.29)
23 0.24
25 0.20
27 (0.17)
29 0.15
31 0.13
33 (0.12)
35 0.10
37 0.09
a
Values are expressed as a percentage of the amplitude
of the fundamental component at full conduction.
b
The values apply to both phase and line currents,
except that triplen harmonics do not appear in the line
currents. Balanced conditions are assumed.

Fig. 6.6 Three-phase TCR with shunt capacitors. The split arrangement of the reactors in each phase
provides extra protection to the thyristor controller in the event of a reactor fault.

maximum of 180 . However, if the reactor in Figure 6.1 is divided into two separate

reactors (Figure 6.7), the conduction angle in each leg can be increased to as much as
360 . This arrangement has lower harmonics than that of Figure 6.1, but the power

losses are increased because of currents circulating between the two halves.