Voltage collapse with closed bus tie

[mbrooke]

Why would a closed bus tie result in voltage collapse for the loss of a primary source in main-tie-main?

 

[topgone]

Primary source is assumed to be a stiff one. Loss of that source will certainly load up the backup source resulting to large current draw, hence a larger voltage drop in the system will occur. There is a point where the system voltage can drop below the level where the field forcing cannot maintain the voltage anymore, core saturation, allowed period of field forcing limits, tap changer's lower/upper limits, etc.

You don't question why such things happen in the system under consideration. It is a product of voltage collapse studies simulated in advance to give the designer points to consider when trying to coordinate settings.

 

[mbrooke]

Primary source is assumed to be a stiff one. Loss of that source will certainly load up the backup source resulting to large current draw, hence a larger voltage drop in the system will occur. There is a point where the system voltage can drop below the level where the field forcing cannot maintain the voltage anymore, core saturation, allowed period of field forcing limits, tap changer's lower/upper limits, etc.

You don't question why such things happen in the system under consideration. It is a product of voltage collapse studies simulated in advance to give the designer points to consider when trying to coordinate settings.

Tap changers not having enough time to adjust is probably the cause from everything I have thought about thus far. Reducing the load on both or lower the trafo Z would probably prevent the issue?