Maintaining stability in power systems is crucial for reliable operation. What can cause transient instability in a power system?
A) Sudden changes in load demand or generation.
B) Short circuits (faults) that are cleared quickly by protective relays.
C) Slow variations in system parameters like voltage and frequency.
D) Power system stability is not affected by transient events.

Transient instability in a power system can be caused by sudden changes in load demand or generation. These sudden changes can disrupt the balance between power supply and demand, leading to instability. This can include events such as the loss of a generator, large load changes, or sudden faults that are not cleared quickly enough. Such disturbances can cause rapid changes in system variables like voltage, current, and frequency, potentially leading to oscillations or system failure if not managed properly.