Which statement correctly describes the relationship depicted by PV curves in voltage stability analysis?

Which statement correctly describes the relationship depicted by PV curves in voltage stability analysis?

• A. PV curves plot voltage as a function of active power output.
• B. PV curves plot voltage as a function of reactive power.
• C. PV curves plot current as a function of voltage.
• D. PV curves plot frequency as a function of voltage.

Answer: (A)

PV curves show how voltage at a bus changes as real power is varied. In voltage stability analysis, you increase the active power (P) and observe the resulting voltage (V); the curve reveals how far you can push P before voltage collapses, with a knee point marking the stability limit. That’s why this option is the best fit: it describes voltage as a function of active power. If you were looking at a curve of reactive power versus voltage, that would be a Q-V relationship; current versus voltage would be an I-V relation; and frequency versus voltage isn’t a PV curve at all.

PV curves show how voltage at a bus changes as real power is varied. In voltage stability analysis, you increase the active power (P) and observe the resulting voltage (V); the curve reveals how far you can push P before voltage collapses, with a knee point marking the stability limit. That’s why this option is the best fit: it describes voltage as a function of active power.

If you were looking at a curve of reactive power versus voltage, that would be a Q-V relationship; current versus voltage would be an I-V relation; and frequency versus voltage isn’t a PV curve at all.