1) A 3-Φ 10MVA, 11kV, generator with a solidly earthed neutral point supplies a feeder. Significant impedances of generator and feeder are given below:
To positive sequences current j1.2 p.u. j1.0 p.u.
To negative sequence current j0.9 p.u. j1.0 p.u.
To Zero sequence current j0.4 p.u. j3 p.u.
A fault from one phase to earth occurs at the far end of the feeder.
Find out the voltage to neutral at faulty phase terminals of generator.
2) Deduce the expression for positive sequence current Ia1 of an unloaded generator when it is subjected to a double line to ground fault.
3) Deduce an expression for fault current in double line-to-ground fault on the unloaded generator in terms of symmetrical components.
4) Deduce swing equation of synchronous machine swinging against the infinite bus. Write down the supposition in deducing the swing equation.
5) Describe Euler’s method of solving swing equation in detail. Write down approximations if any.