Page 251 - Hybrid-Renewable Energy Systems in Microgrids

228 Hybrid-Renewable Energy Systems in Microgrids

Many researchers have investigated the simplified simulation models, for example,
power efficiency models [40–44], which can predict the time series or average per-
formance of a PV array under various climatic conditions for different engineering
applications.
In their study, Kerr and Cuevas [37] investigated a new methodology to deter-
mine the current–voltage (I–V) characteristics of PV modules based on simultane-
ously measuring the open-circuit voltage (V oc ) as a function of a slowly varying light
intensity. They also detailed the theoretical analysis and interpretation of such quasi-
steady-state V oc measurements.
Researchers Borowy and Salameh [41] presented a simplified model to calculate
the maximum power output for one certain PV module after finding the solar radiation
on the PV module and ambient temperature data.
A novel simulation model for PV array performance predictions for engineering
applications has been presented by Zhou et al. [42]. This model is based on the I–V
curves of a PV module. Five parameters have been introduced to account for the com-
plex dependence of PV module performance upon solar radiation intensities and PV
module temperatures. According to the author, this simple simulation model is useful
for engineers to calculate the actual performance of the PV modules under operating
conditions, where limited data is provided by the PV module manufacturers.
An efficiency model of PV module power output that is based on an adaptation of
the established PV fill factor method, was presented by Jones and Underwood [44,45].
They attempted to consider the solar radiation and temperature characteristics in the
established theory to make a general PV power efficiency mode. The AC power output
from a PV array was estimated using the product of a single PV module power output,
the number of PV modules N m in the array, and the inverter efficiency η inv can be rep-
resented as in (Eq. (12.1)) [44,45].

In KG)
1 (
P Array FF • =   I SCO • G   •   V OCO • In KG ) • T 0   • N •η inv (12.1)
m
PArray=FF⋅ ISCO⋅ GG 0  Go  1 ( 0 T module 
⋅ VOCO⋅ InK GInK G ⋅ -
0
1
1
2
6
T Tmodule⋅Nm⋅ηinv where: K 1 = Constant k1 = around 10 m /W, I sco = the short circuit current (A), V oco = the
0
2
open circuit voltage (V), G = the solar irradiation on an inclined plane in (W/m ),
2
G 0 = solar irradiance reference (1000 W/m ), N = number of modules constituting
the PV field, and FF = form factor.
The developed simulation model has been validated using measured data from
a 39.5 kW building-integrated PV array system. The PV module power output was
calculated for two different sets of climatic conditions, for clear sky conditions and
overcast sky conditions. The datasets were compiled from all periods of the year for
this purpose.
3.2 Modelling the wind energy system
The mathematical modelling of wind energy conversion system includes wind turbine
dynamics and generator modelling. An investigation of the available literature on the