A 3-phase, wye-connected, 11.8 kV, 100 MVA turbo- generator of 0.8 power factor lagging has a synchronous reactance of 2.0 p.u. on rating. The generator is driven by a steam turbine delivering a maximum power of 90MW. It is known that the fielf current limit in a (P,Q) plane can be represented in terms of the line-to-line voltages and 3-phase powers as:
Where Emax and Pmax are the maximum induced voltage (e.m.f.) and real power respectively. Assume the generator to be ideal for convenience of analysis.
A. Sketch the capability curve clearly indicating the characteristic operating limits.
B. What is the maximum reactive power the generator can produce?
C. Can this generator supply 70 MW at 0.7 power factor lagging? Explain your answer.