Bus tie breakers not closing before synchronizing power stations

Hi,

We have two power stations and they are running in parallel. At one stage the earthquake tremor occurs and causes the bus tie circuit breakers to opened by protection relays.

So when we started up we had a problem with the bus tie breakers closing before synchronizing the two stations. Now the bus tie breakers can only be closed after synchronizing both stations first.

Please give some expert advice on how to do this kind of switching in the future.

I think it would be very difficult to comment on your situation without being able to review the electrical schematics for the units and the tie breakers. The answer to your question probably resides in those drawings, that there are some permissives which must be met before certain actions can be completed. Without being able to review the schematics for the breaker close circuits for the two plants and the tie breakers, we couldn't make an informed comment or recommendation.

Review the drawings, or have someone who's familiar with the drawings in use at the sites to develop a list of permissives which must be satisfied before synchronization or closing the tie breakers under various scenarios. That will tell you something about how the plants and tie breaker schemes were designed, and then with that knowledge you can develop an operating procedure for each scenario which is specific and unique to your plant.

A review of the schematics sometimes reveals issues which were never anticipated when the plants were designed and may lead to changes necessary to improve the ability to respond to unanticipated scenarios.