The specified quantities of Generation bus is

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$P$ and $V$

Explanation: In power system load flow studies, a Generation bus (also known as a PV bus or Voltage-controlled bus) is characterized by the specification of its real power (P) and voltage magnitude (V). Since the bus is connected to a generator, its voltage can be regulated by adjusting the excitation system, while the power output is determined by the prime mover governor settings.

Working Principle: The load flow problem requires solving for four variables at every bus: P, Q, V, and $\delta$. In a PV bus, P and V are treated as independent input quantities because the generator control systems (AVR for V and governor for P) maintain these parameters at constant values. The dependent variables to be solved are the reactive power (Q) and the phase angle (\delta).

Key Formulas: $P = \sum_{j=1}^{n} |V_i||V_j||Y_{ij}| \cos(	heta_{ij} - \delta_i + \delta_j)$ — Real power balance equation; $Q = -\sum_{j=1}^{n} |V_i||V_j||Y_{ij}| \sin(	heta_{ij} - \delta_i + \delta_j)$ — Reactive power balance equation

Key Points: Slack bus (Swing bus): $V$ and $\delta$ are specified.; PV bus (Generator bus): $P$ and $V$ are specified.; PQ bus (Load bus): $P$ and $Q$ are specified.; The number of equations for a PV bus is reduced because voltage magnitude is constant.

Advantages: Facilitates voltage regulation via AVR.; Simplifies iterative load flow calculations by fixing two variables.

Disadvantages: Requires reactive power limits ($Q_{min}, Q_{max}$) to be checked.; If Q limits are violated, the bus may convert to a PQ bus.

Applications: Modeling of thermal and hydro power plants in grid analysis.; Steady-state stability studies.

Additional Info: Option B (Q and V) represents an invalid specification as a primary load flow input.. Option C (V and $\delta$) defines the Slack/Swing bus, not the Generation bus.. Option D (P and Q) describes the characteristics of a Load bus (PQ bus).

Answer: A is correct — The generation bus is defined by the fixed active power injection and regulated voltage magnitude.

Exam Tip: Remember the mnemonic: PV bus is for Power and Voltage regulation, Slack bus is for Slack (Swing) of reference angle, and PQ bus is for typical Loads.

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