ABSTRACT
Power systems worldwide are 3-phase, 60 Hz or 50 Hz AC. The three phases (coils) of the generator are connected in Y or
∆
as shown in Figure 14.1. In balanced threephase operation, the line-to-line voltage, the line current, and the three-phase power
P
in terms of the phase voltage
V
, phase current
I
, and load power factor
pf
are given by the following expression, with notations marked in Figure 14.1. In a Y-connected system:
V
=
√
V
I
=
I
P
=
√
V
I
pf
(14.1)
In a
∆
-connected system:
V
=
V
I
=
√
I
P
=
√
V
I
pf
(14.2)
For steady-state or dynamic performance studies, the system components are modeled to represent the entire system. The components are modeled to represent the conditions under which the performance is to be determined. Electrical generators, rectifiers, inverters, and batteries were discussed in earlier chapters. This chapter concerns system-level performance.
