Information Technology Reference
In-Depth Information
Fig. 1.
Two terminals simple network
where:
F
=1+
Z
LD
Z
LN
2
+2
Z
LD
Z
LN
cos(
θ
−
φ
)
(4)
From (2), the load power,
P
R
, increases as
Z
LD
is decreased gradually, hence the
power transmitted will increase. As the value of
Z
LD
approaches
Z
LN
the value
of PR starts to decrease gradually due to
F
. However, from (3), the receiving
voltage
V
R
decreases gradually as
Z
LD
decreases.
C. QV Curve
From (2) and (3), it can be seen that the power factor
φ
of the load has a
significant impact on the overall equations. This is to be expected because the
voltage drop in the line is a function of both active and reactive power transfer.
Hence, the QV curves may also be used to assess voltage stability of the system.
The bottom of the QV curves, in addition to identifying the stability limit,
defines the minimum reactive power requirement for the stable operation.
This paper takes account the sensitivity and the sensitivity change rate of
comprehensive sensitivity indicators
L
i
.
L
i
=
LM
i
/LM
+
ΔLM
i
/ΔLM
(5)
Where:
LM
i
=
dV
i
/dQ
i
(6)
ΔLM
i
=
LM
i
1
−
LM
i
2
(7)
In the above equations,
LM
i
- the sensitivity of the voltage of node
i
on the load;
LM
i
1
- the sensitivity of the voltage of node
i
on the load at the first state;
LM
i
2
- the sensitivity of the voltage of node
i
on the load at the second state;
ΔLM
i
- the change rate of the sensitivity of node
i
;
LM
-the average value of the sensitivity of each node;
ΔLM
-the average value of the change rate of the sensitivity of each node.
Search WWH ::
Custom Search