# Aerodynamic Model: WTGAR_A and WTARA1

In PTI: **WTARA1** is the same as **WTGAR_A** model.

AutoCorrection Properties

Following checks and corrections are applied during Validation and AutoCorrection.

- If Ka = 0 then Error is created because Ka > 0.
- If Theta < 0 then Error is created because That >= 0.

Mult represents the user-specified value **Minimum time constant size as multiple of time step** option on the Validation page of the Transient Stability Dialog

TimeStep represents the integration time step being used as described on TimeStep

Model Equations and/or Block Diagrams

**Parameters for WTGAR_A:**

Ka | Aero-dynamic gain factor |

Theta | Initial Pitch Angle |

MVABase | MVA Base |

**Parameters for WTARA1:**

Ka | Aero-dynamic gain factor |

Theta | Initial Pitch Angle |