Symbol | Meaning | Unit |

ΔP | Conventional turbine mechanical power deviation | p.u. |

ΔP | Wind turbine mechanical power deviation | p.u. |

ΔP | Disturbance power | p.u. |

Δf | Deviation of system frequency | p.u. |

P | Instruction power | w |

T | Speed governor time constant | sec |

F | Reheat time constant | sec |

T | Turbine time constant | sec |

D | Load-damping constant | - |

K | Integral gain of secondary frequency control | - |

R | Regulation coefficient of primary control | - |

H | Inertia of generators and motors | - |

s | Laplace operator | - |