Wind Turbine Induction Generator (Phasor Type)

Implement phasor model of squirrel-cage induction generator driven by variable pitch wind turbine

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Libraries:
Simscape / Electrical / Specialized Power Systems / Electrical Machines

Description

The wind turbine and the induction generator (WTIG) are shown below. The stator winding is connected directly to the grid and the rotor is driven by the wind turbine. The power captured by the wind turbine is converted into electrical power by the induction generator and is transmitted to the grid by the stator winding. The pitch angle is controlled in order to limit the generator output power to its nominal value for high wind speeds. In order to generate power the induction generator speed must be slightly above the synchronous speed. But the speed variation is typically so small that the WTIG is considered to be a fixed-speed wind generator. The reactive power absorbed by the induction generator is provided by the grid or by some devices like capacitor banks, SVC, STATCOM, or synchronous condenser.

Pitch Angle Control System

The wind turbine model uses the Wind Turbine block of the Renewables/Wind Generation library. See documentation of this block for details.

A Proportional-Integral (PI) controller is used to control the blade pitch angle in order to limit the electric output power to the nominal mechanical power. The pitch angle is kept constant at zero degrees when the measured electric output power is under its nominal value. When it increases above its nominal value, the PI controller increases the pitch angle to bring back the measured power to its nominal value. The control system is illustrated in the figure below:

Examples

Wind Farm - Induction Generator

Phasor simulation of a 9-MW wind farm using Induction Generators (IG) driven by variable-pitch wind turbines.

• Open Model

Ports

Input

wind — Wind signal

Simulink^® signal

Simulink input of the wind speed in m/s.

Dependencies

To enable this port, clear the External turbine (Tm mechanical torque input) parameter.

Tm — Mechanical load torque

Simulink signal

Simulink input of the mechanical torque. Tm must be negative for power generation. Use this input when using an external turbine model.

Dependencies

To enable this port, select the External turbine (Tm mechanical torque input) parameter.

Trip — Mechanical load torque

0 | 1

Apply a Simulink logical signal (0 or 1) to this input. When this input is high the WTIG is disconnected. Use this input to implement a simplified version of the protection system.

Output

m — Measurement signal

vector

Simulink output vector containing 8 WTIG internal signals. These signals can be individually accessed by using the Bus Selector block. They are, in order:

Signal	Signal Names	Definition
1	Vabc (cmplx) (pu)	Phasor voltages (phase to ground) Va, Vb, Vc at the WTIG terminals in pu based on the generator ratings.
2	Iabc (cmplx) (pu)	Phasor currents Ia, Ib, Ic flowing into the WTIG terminals in pu based on the generator ratings.
3	P (pu)	WTIG output power in pu based on the generator ratings. A positive value indicates power generation.
4	Q (pu)	WTIG output reactive power in pu based on the generator ratings. A positive value indicates reactive power generation.
5	wr (pu)	Generator rotor speed (pu)
6	Tm (pu)	Mechanical torque applied to the generator in pu based on the generator ratings.
7	Te (pu)	Electromagnetic torque in pu based on the generator ratings.
8	Pitch_angle (deg)	Blade pitch angle in degrees.

Conserving

A — Terminal A

specialized electrical

Specialized electrical conserving port associated with the terminal A of the WTIG.

B — Terminal B

specialized electrical

Specialized electrical conserving port associated with the terminal B of the WTIG.

C — Terminal C

specialized electrical

Specialized electrical conserving port associated with the terminal C of the WTIG.

Parameters

To edit block parameters interactively, use the Property Inspector. From the Simulink Toolstrip, on the Simulation tab, in the Prepare gallery, select Property Inspector.

Generator

External turbine (Tm mechanical torque input) — Option to use external turbine

off (default) | on

When this parameter is selected, the Turbine tab is not visible in the mask dialog box, and a Simulink input named Tm appears on the block, allowing to use an external signal for the generator input mechanical torque. This external torque must be in pu based on the nominal electric power and synchronous speed of the generator. For example, the external torque may come from a user defined turbine model. By convention for the induction machine, the torque must be negative for power generation

Nominal power, line-to-line voltage and frequency [Pn(VA), Vn(Vrms), fn(Hz)] — Nominal power, line-to-line voltage, and frequency

[1.5e6/0.9, 575, 60] (default)

Nominal power in VA, the nominal line-to-line voltage in Vrms and the nominal system frequency in hertz.

Stator [Rs, Lls] (pu) — Stator resistance Rs and leakage inductance Lls

[ 0.004843, 0.1248] (default)

Stator resistance Rs and leakage inductance Lls in pu based on the generator ratings.

Rotor [Rr', Llr'] (pu) — Rotor resistance Rr' and leakage inductance Llr'

[ 0.004377, 0.1791] (default)

Rotor resistance Rr' and leakage inductance Llr', both referred to the stator, in pu based on the generator ratings.

Magnetizing inductance Lm (pu) — Magnetizing inductance Lm

6.77 (default)

Magnetizing inductance Lm in pu based on the generator ratings.

Inert constant, friction factor, and pairs of poles [H(s), F(pu), p] — Inert constant, friction factor, and pairs of poles

[5.04, 0.01, 3] (default)

Combined generator and turbine inertia constant H in seconds, combined viscous friction factor F in pu based on the generator ratings and number of pole pairs p.

You may need to use your own turbine model, in order for example, to implement different power characteristics or to implement the shaft stiffness. Your model must then output the mechanical torque applied to the generator shaft. If the inertia and the friction factor of the turbine are implemented inside the turbine model you specify only the generator inertia constant H and the generator friction factor F.

Initial conditions [s, th(deg), ias, ibs, ics (pu), ph_as, ph_bs, ph_cs (pu)] — Initial slip, electrical angle, stator current magnitude,and phase angle

[-0.01,0, 0,0,0, 0,0,0] (default)

Initial slip s, electrical angle Θ in degrees, stator current magnitude in pu, and phase angle in degrees.

Turbine

This tab is not visible when you select the External turbine (Tm mechanical torque input) parameter.

Pitch angle beta used to display characteristics (beta >= 0) — Pitch angle used to display the wind turbine power characteristics

0 (default)

Pitch angle used to display the wind turbine power characteristics.

Dependencies

To enable this parameter, clear the External turbine (Tm mechanical torque input) parameter.

Nominal wind turbine mechanical output power (W) — Nominal turbine mechanical output power

1.5e6 (default)

Nominal turbine mechanical output power in watts.

Dependencies

To enable this parameter, clear the External turbine (Tm mechanical torque input) parameter.

Base wind speed (m/s) — Base value of wind speed

9 (default)

Base value of the wind speed, in m/s, used in the per unit system. The base wind speed is the mean value of the expected wind speed. This base wind speed produces a mechanical power which is usually lower than the turbine nominal power.

Dependencies

To enable this parameter, clear the External turbine (Tm mechanical torque input) parameter.

Base rotational speed (pu of base generator speed) — Rotational speed at maximum power for base wind speed

1 (default)

Rotational speed at maximum power for the base wind speed. The base rotational speed is in pu of the base generator speed.

Dependencies

To enable this parameter, clear the External turbine (Tm mechanical torque input) parameter.

Maximum power at base wind speed (pu of nominal mechanical power) — Maximum power at base wind speed of nominal mechanical power

1 (default)

Maximum power at base wind speed in pu of the nominal mechanical power.

Dependencies

To enable this parameter, clear the External turbine (Tm mechanical torque input) parameter.

Pitch angle controller gain [Kp Ki] — Proportional and Integral gains of pitch controller

[5 25] (default)

Proportional and Integral gains Kp and Ki of the pitch controller. Specify Kp in degrees/(power deviation pu) and Ki in degrees/(power deviation pu)/s. The power deviation is the difference between actual electrical output power and the nominal mechanical power in pu of the generator nominal power.

Dependencies

To enable this parameter, clear the External turbine (Tm mechanical torque input) parameter.

Maximum pitch angle (deg) — Maximum pitch angle

45 (default)

Maximum pitch angle in degrees.

Dependencies

To enable this parameter, clear the External turbine (Tm mechanical torque input) parameter.

Maximum rate of change of pitch angle (deg/s) — Maximum rate of change of pitch angle

2 (default)

Maximum rate of change of the pitch angle in degrees/s.

Dependencies

To enable this parameter, clear the External turbine (Tm mechanical torque input) parameter.

Display wind turbine power characteristics — Plot turbine power characteristics at specified pitch angle for different wind speeds

Click to plot the turbine power characteristics at the specified pitch angle for different wind speeds.

Dependencies

To enable this parameter, clear the External turbine (Tm mechanical torque input) parameter.

References

[1] Siegfried Heier, “Grid Integration of Wind Energy Conversion Systems,” John Wiley & Sons Ltd, 1998, ISBN 0-471-97143-X

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2006a