Explain the per unit system of analyzing power system problems. How does it reduce the efforts of power system engineers?

A single-phase two-winding transformer is rated 20 kVA, 480/120 volts, 60 Hz. The equivalent leakage impedance of the transformer referred to the 120 volts winding, denoted winding is Zeq2 L0.0525 78.13 ohm. Using the transformer ratings as base values, determine the per-unit leakage impedance referred to winding 2 and referred to winding 1.

What are short circuit studies? Explain in detail.

Deduce and draw the sequence network for a line-line to ground fault at the terminals of an unloaded generator.

Explain the flow chart of Gauss-Seidel method used for load flow study in power system.

Discuss the purpose of load flow studies of a power system.

Explain Equal Area criterion for transient stability during a three-phase fault.

Why is steady state stability limit higher than transient stability limit? Explain the various techniques for improving transient stability.

Deduce the general expression for reflection and refraction of travelling wave.

Determine the reflection and refraction for short circuit transmission line. Why is the grid sub-station usually connected to the overhead line through short length of cable?

Derive an expression for Swing Equation for an alternator with negligible damping connected to an infinite bus-bar.

Discuss about the current limiting reactors. Write where are they used with their suitable application.

7. Write short notes on any two of the following:

Role of computer method in power systems

Newton-Raphson method for load flow analysis

Velocity of propagation