**3.4 Battery model**

128 Fossil Fuel and the Environment

coefficient of the rotor (Cp) or theoretical maximum rotor efficiency which is the fraction of the upstream wind power that is captured by the rotor blade. It should be noted from (6) that the wind power varies with the cube of the air velocity. Therefore, a slight change in

Wind speed Net

Meters/second Miles/hour (kW)

10 0 0

2 5 11.18468 2

3 10 22.37 40

4 11.5 25.725 50

5 13.5 30.1986 60

6 15 33.554 63

7 17 38.028 65

8 19 42.5 63

9 21 46.975 62

10 22.5 50.331 61

The air density 'ρ' can be corrected for the site specific temperature and pressure in

RT

where 'ρ' is the density of air, 'p' is the air pressure, 'R' is the gas constant, and 'T' is the

The PV model block calculates the PV power (kW) and the total PV energy (kWh) supplied

power output

<sup>p</sup> <sup>ρ</sup> (7)

PPV pv η \*ins\*A\*PV (8)

wind speed results in a large change in the wind power.

Table 1. Look-Up Table for the 15/50 AOC Wind Turbines

by the PV array using the following equations.

accordance with the gas law

temperature.

**3.3 PV model** 

and

Sr. No.

> In the Simulink® model, the battery bank is modeled so that it acts as a source of power, rather than back-up power. The battery model block controls the flow of power to and from the battery bank. A roundtrip efficiency of 90% is assumed for the battery charge and discharge cycle. The battery model incorporates the effect of ambient temperature as described in (Winsor & Butt, 1978) into the hybrid power system model. Therefore, the model can be used for cold region applications.

> The life of the battery bank depends on the depth of discharge and the number of charge discharge cycles. In the Simulink® model the battery bank is modeled so that it acts as a source of power rather than back-up power. Therefore, the depth of discharge of the battery-bank is assumed between 95% and 20% of the rated capacity. This higher depth of discharge reduces the number of battery operating cycles for the same energy output. It should be noted that the number of battery cycles plays a more significant role in the life of the battery bank.
