SKM PTW Generator Question

[samir]

Hello, I use the software package PTW to do the Power System Studies. I have recently graduated and started working on it. I am confused on the power factor to be used in generator data. Should it be lead or lag. As per my understanding I always assume to be lag as most of the load downstream is lagging in nature (induction). But I have seen people using lead as well.

How to decided on what feature lead or lag to be used for the studies and how does it affect the studies?

 

[beanland]

Standby vs Parallel

Standby vs Parallel

A standby/emergency generator, since it serves load, unless the load is capacitive, will almost always operate lagging (real and reactive power in the same direction.) However, a generator run in parallel with another source (e..g. utility) can run either leading or lagging depending on the level of excitation. Under-excited (low voltage), the generator will consume reactive power; over-excited (high voltage) will generate reactive power. A parallel generator operated in voltage-control mode may operate either leading or lagging.

 

[samir]

A standby/emergency generator, since it serves load, unless the load is capacitive, will almost always operate lagging (real and reactive power in the same direction.) However, a generator run in parallel with another source (e..g. utility) can run either leading or lagging depending on the level of excitation. Under-excited (low voltage), the generator will consume reactive power; over-excited (high voltage) will generate reactive power. A parallel generator operated in voltage-control mode may operate either leading or lagging.

This was really helpful. In this case the generator is an emergency standby generator mainly serving motor loads. It should be lagging right?

 

[beanland]

Motors

Motors

Yes, since motors typically consume reactive power to magnetize their windings, the generator will be supplying the reactive power along with real power, thus the real and reactive are in the same direction, and thus lagging.