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Methods
Wind turbine systemMethods
Wind turbine system
Wind turbine acquires the mean power production
characteristic which varies according to determinations of
the producer. Wind turbine starts generating electricity at
their cut-in speed then power starts to increase until turbine
reaches the rated speed. It should be noted that power
curve of wind turbines is one of very significant
characteristics, which describes the relation of the power
produced by the turbine with a rotational speed [8][9]. The
total annual power (W
E
) in (kWh) generated by wind turbine
can be represented via equation (1) below:
(1)
∑
where (N
h
) is the number of data hour in the year, (t) is the
hour of the year, (P
tr
) is the power output in (kW) as function
of the average wind speed over a given hour, and (N
tr
) is
the numbers of turbines at the site [7].
The wind power output (P
w
) in (kW) is specified by the
following relation in equation (2), where (p
α
) is the air
density ≈ (1.22 g/
3
), (A) is the swept area of wind turbine
rotor in (m
2
), (V
r
)
is the velocity of wind in (m/s), (C
p
) is the
wind turbine power coefficient, (n
g
) is the efficiency of wind
generator and (n
t
) is the efficiency of wind turbine.
(2)
α
Photovoltaic system
The following relation in equation (3) can calculate the
total annual power (S
E
) results from Photovoltaic system in
(kWh). Where (N
h
) is the number of data hour in the year, (t)
is the hour of the year, (A
solar
) is the fixed area of the solar
field in (m
2
), (G
t
) is the hourly insulation in (Wm
-2
), (n
solar,t
) is
the solar system efficiency for a specified hour of day
through a given month [10].
(3)
∑
,
The output power of the photovoltaic system (p
pv
) in
(kW) expressed in the following relation in equation (4).
Where (f
PV
) is the derating factor percentage for the
photovoltaic array, (Y
PV
) is the photovoltaic array rated
capacity in (kW), which is the power production under STC.
(G
T,STC
) is the incident solar insolation at STC (1 kW/m
2
),
(G
T
) is the solar insolation incident on the PV array at the
current time step in (kW/m
2
), (T
c,STC
) is the temperature of
the photovoltaic cell under STC which is 25°C, (T
c
) is the
temperature of the photovoltaic cell at the current time step
in (°C), and (α
P
) is the power temperature coefficient in
(%/°C). [11][12][13].
(4)
.
,
1
,
The following relation in equation (5) determines the
total annual power output in (kWh) obtained from the
renewable hybrid system (H
E
) that denotes to the sum of
PV power (S
E
)
and WT power (W
E
) [14]:
(5)
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