Correct Answer - Option 4 : 1 and 2

Transient stability: Transient stability is the ability of the power system to maintain synchronism when subjected to a severe transient disturbance.

Transient stability of the system can be improved by

- Increasing the system voltage
- Increase in the X/R ratio
- High speed circuit breakers help to clear the fault as quick as possible
- By turbine fast valving
- High speed excitation
- Use of auto re-closing breakers
- Some of the other ways to improve the transient stability are by employing lightning arresters, high neutral grounding impedance, single pole switching, quick Automatic Voltage Regulators (AVRs).

**Steady-state stability** of a power system is

\({P_{max}} = \frac{{EV}}{X}\)

We can increase the **steady state stability by decreasing the reactance X**. In **double circuit line the reactance is less than the single line circuit.**

**Series capacitors** are used to compensate for the inductance of the transmission line. They will increase the **transmission capacity and the stability of the line**. These are also used to share the load between parallel lines.