Question

Three generators are feeding a load of 100 MW. The details of the generators are

	Rating(MW)	Efficiency (%)	Regulation (pu) on 100 MVA base
Generator-1	100	20	0.02
Generator- 2	100	30	0.04
Generator - 3	100	40	0.03

In the event of increased load power demand, which of the following will happen?

• A. All the generators will share equal power
• B. Generator-3 will share more power compared to Generator-1
• C. Generator-1 will share more power compared to Generator-2
• D. Generator-2 will share more power compared to Generator-3

Answer 1

The correct option is C Generator-1 will share more power compared to Generator-2

Let x${}_1$, x${}_2$ and x${}_3$ are reactances of generator-1 generator-2 and generator-3 respectively.

Neglecting armature resistance of all the three generators

$V{R}_1$ = 0.02 p.u.

$V{R}_2$ = 0.04 p.u and

$V{R}_1$ < $V{R}_3$ < $V{R}_2$

Since, voltage regulation (VR) $\propto$ reactance of generator.

$X_1<X_3<X_2$

$Powersharedbyagenerator\propto \frac{1}{\text{reactance of generator}}$

Power shared by

Generator 1 > Generator 3 > Generator 2

Load sharing is independent of efficiency of alternators.