Description: Fig. 1  illustrates the single  line diagram of the wind  power  plant and the  utility grid

considered for this practical.

Fig. 1 Single-line diagram of the wind power plant and the grid.

Fig.2 Block diagram model of the wind power plant and grid in Simulink.

Instructions: Fig. 2 illustrates the corresponding Simulink model block diagram and the procedure for

developing the block diagram is given in the instructions.

1.  Open MATLAB from “Start” menu.

2.  Select “Open” → Open the Simulink model saved from Practical 01.

3.  Select “File” → Save as → Save the Simulink file with a different name.

4.  Click “Simulink Library” icon in the tool bar to get the window of the Simulink library.

5.  Search for the following blocks and drag & drop them into your Simulink file.

• Three-phase PI section line, Three-phase transformer (two winding), Three-phase V-I measurement, Uniform Random Number, Scope, Abs, Step, Sum

6.  Delete only the lines connecting the “Three-Phase Source” and the “Three-Phase Series RLC load” . Insert the new elements and connect all as in Fig.2.

7.  Double click on the “Three-phase Source” and enter the following parameters:

• Phase-to-phase rms voltage = 25 kV, Frequency = 60Hz, Phase angle = 0, 3-phase short circuit level = 100e6 VA, X/R ratio = 7, Base voltage = 25 kV

8.   Double click on the “Three-phase PI section line” and enter the following parameters:

• Frequency = 60 Hz

• Line length = 10 km

9.  Double click on the “Transformer” and enter the following parameters:

• In the “Configuration” tab → winding 1 “Yg” and winding 2 “Delta (D1)”

• In the “Parameters” tab → Nominal power = 12.0 MVA, frequency = 60 Hz, Winding

1 parameters = [25e3, 0.002, 0.08], Winding 2 parameters = [575, 0.002, 0.08], Magnetizing resistance = 500, Magnetizing inductance = inf

10. Double click on the ‘Three-phase load’ block and enter the following parameters:

• In the “Parameters” tab → Nominal phase-to-phase voltage = 575 V, configuration = Y (grounded), frequency = 60 Hz, active power = 500 kW, Inductive and capacitive reactive power = 0

• In the “Load flow” tab → load type “Constant Z”

11. Double click on the ‘Wind Turbine’ model and enter the following parameters:

•    Select the “Generator” option → Nominal power, line-to-line voltage, frequency = [6*1.5e6/0.9  575  60],  Stator  =  [  0.00706  0.171],  rotor  =  [  0.005  0.156], Magnetizing inductance = 2.9, Inertia constant, friction factor, and pairs of poles = [5.04 0.01 3], Initial conditions = [0.2 0 0 0 0 0]

•    Select the “Turbine” option → Nominal wind turbine mechanical output power = 6*1.5e6, Tracking characteristic speeds = [0.7 0.71 1.2 1.21], Power at point C = 0.73, Wind speed at point C = 12, Pitch angle controller gain = 500, Maximum pitch angle = 45, Maximum rate of change of pitch angle = 2

•    Click on the “Display wind turbine characteristics” and obtain the wind turbine characteristics.

•    Select the “Converters” option → Just change the DC bus capacitor to 6*10000e- 6

• Save the figure.

12. Remove the “Step” block connected to the “Wind” input of the DFIG model. Connect the “Sum” block and other “Step” blocks as in Fig. 2.

13. Double click on the “Sum” block and in the “List of signs” enter |++++

14. In order to obtain the variation of wind speed connect the uniform random number and three different step blocks to the summation block as illustrated in Fig. 2 and enter the following parameters:

15. Set the “Simulation Stop Time” in the tool bar to “400” as follows:

16. Run the simulation by clicking on the “Run” icon in the tool bar.

17. Double click on all the scopes and observe the parameter variations. Click the “Auto scale” icon on the scope toolbar to view the full simulation.

18. To open the Workspace browser if it is not currently visible, do either of the following:

•    Type workspace at the Command Window prompt.

•    The variables you selected from the DFIG in the previous section (P(pu), Q(pu), pitch angle, Tm, wr) are saved in the “yout” matrix.

19. Type the following command in the command window and press “Enter”:

•    plot(yout( :,1),yout(:, 2))

The x-axis of the graph denotes the time variable while the y-axis represents the second output coming from the wind generator model.

20. In order to add labels to the x-axis and y-axis and a title, select “Insert” in the graph and select the appropriate labels and title. Then type the label names and the title.

21. Similarly, plot the following outputs from the wind generator in separate figures and save all the figure files. Submit the graphs in a report.

•    Time vs Active power, Time vs Reactive power, Time vs Wind speed, Time vs Pitch angle, Time vs Rotor speed, Time vs Mechanical Torque