Stability study for a power system

[mbch]

Good day everybody.
I have a system which needs some modification. One of them is to run two generator in parallele. This system now has two gen (one=on, one=off) I need to add a third one, that implies incorporate the gen to the syncronizer system and this gen is going to work like the system spare. So for the units running 50% of the load. Do you think is necessary to check the stability of the system knowing that the gen are: 1250kW, 480V, 3p, 60hz. I am going to check the load flow, short circuit and starting of the motor for the system, but I do not know if stability is required. I appreciate your help in this matter.
Thanks

 

[kingpb]

Stability is the way the system responds to disturbances and the ability to return to normal operation. If you are concerned with synchronism after a major disturbance, which could include load changes, then a transient stability study may be in order. If the change in system is slow or gradual then you may be need to do a dynamic or steady-state stability study.

If the system you are modifying is critical in nature, then it may be a good exercise especially if you are using the more traditional paralleling equipment which is inherently complex, and less stable for load sharing. If you are going to incorporate the new digital controller technology, the gens share load a lot easier and I don't think stability would be such an issue, but again it depends on the critical nature of your system and how it's being utilized.

 

[jdsmith]

Are you going to run this system islanded - disconnected from the utility? If so a transient stability study should be done. Otherwise I agree with kingpb, it all depends on how reliable this needs to be. In the petrochemical world any time generators or synchronous motors are modified we require a stability study.