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Fig 2.5 P, Q[according to general calculation]
Note
When phase difference between voltage and current is within 90 degree of lead and lag, power
factor is positive. However, when phase difference is more than 90 degree[miswiring,
regeneration], power factor and active power are negative.
Method 2: Calculation of Harmonics
Method 2 is used to obtain reactive power from apparent and active power, and the overall
apparent power by using calculation of vector apparent power.
=
T
a
a
a
dt
t
I
t
V
T
P
0
)
(
)
(
1
,
=
T
b
b
b
dt
t
I
t
V
T
P
0
)
(
)
(
1
,
=
T
c
c
c
dt
t
I
t
V
T
P
0
)
(
)
(
1
c
b
a
P
P
P
P
+
+
=
arms
arms
a
I
V
S
=
,
brms
brms
b
I
V
S
=
,
crms
crms
c
I
V
S
=
2
2
a
a
a
P
S
Q
−
=
,
2
2
b
b
b
P
S
Q
−
=
,
2
2
c
c
c
P
S
Q
−
=
,
c
b
a
Q
Q
Q
Q
+
+
=
