# Exciter Model: EXAC1

AutoCorrection Properties

Following checks and corrections are applied during Validation and AutoCorrection.

- If 0.0 < Tr < 0.5*Mult*TimeStep then Tr = 0, ElseIf 0.5*Mult*TimeStep < Tr < Mult*TimeStep then Tr = Mult*TimeStep
- If 0.0 < Tb < 0.5*Mult*TimeStep then Tb = 0, ElseIf 0.5*Mult*TimeStep < Tb < Mult*TimeStep then Tb = Mult*TimeStep
- If 0.0 < Ta < 0.5*Mult*TimeStep then Ta = 0, ElseIf 0.5*Mult*TimeStep < Ta < Mult*TimeStep then Ta = Mult*TimeStep
- If 0 < Te < Mult*TimeStep then Te = Mult*TimeStep
- If 0 < Tf < Mult*TimeStep then Tf = Mult*TimeStep
- If Vrmax < Vrmin then swap the values

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

Following treatment is handled during the transient numerical simulation

- If Vr > Vrmax, then Vrmax = Vr or if Vr < Vrmin, then Vrmin = Vr

Model Equations and/or Block Diagrams

**Parameters:**

Tr | Filter time constant, sec |

Tb | Time constant, sec |

Tc | Time constant, sec |

Ka | Voltage regulator gain |

Ta | Voltage regulator time constant, sec |

Vrmax | Maximum exciter control signal, pu |

Vrmin | Minimum exciter control signal, pu |

Te | Exciter field time constant, sec |

Kf | Rate feedback gain, pu |

Tf | Rate feedback constant, sec |

Kc | Rectifier loading factor proportional to commutating reactance |

Kd | Exciter internal reactance, pu |

Ke | Exciter field resistance constant, pu |

E1 | Field voltage value, 1 |

SE1 | Saturation factor at E1 |

E2 | Field voltage value, 2 |

SE2 | Saturation factor at E2 |

Spdmlt | If not zero, multiply output (Efd) by generator speed |