Civil Engineering Reference
In-Depth Information
14
Electrical P
erformance
14.1
Voltage Current and Power Relations
The power systems worldwide are 60 Hz or 50 Hz AC three-phase systems.
The three coils (phases) of the generator are connected in Y or
as shown
in
Figure 14-1
.
In the balanced three-phase operation, the line-to-line voltage,
the line current and the three phase power in terms of the phase voltage and
current are given by the following equations, with notations marked in
In the Y connected system:
∆
V
=
3
V
L
ph
I
=
I
(14-1)
L
ph
P
=
3
V I
pf
3
−
ph
LL
Where pf = power factor
In the
∆
connected system:
VV
=
L
ph
I
=
3
I
(14-2)
L
ph
P
=
3
V I
pf
3
−
ph
LL
For steady state or dynamic performance studies, the system components
are modeled so as to represent the entire system. The power generator, the
rectifier, the inverter, and the battery models were discussed in the earlier
chapters. The components are accurately modeled to represent the conditions
under which the performance is to be determined. This chapter concerns
itself with the system level performance.
