earlier i was tried to synchronize DG set(7MW) with the grid. but after synch, the whole plant was blackout. i was checked phase sequence every thing was ok but how this think occurred. plz reply regarding my problem.

i also want to know what is the impact of phase angle difference when you going for synchronizing and closed the breaker. and also briefed what is exactly occurred during synchronizing? how the two source voltage/frequency/phase angle were match?

if sir u having some diagram or any animation then please send to me on my email id- ravinderrana112 [at] gmail.com. i wait for your reply sir.

 

Oh, there are bells and buzzers going off in my head.

How many times has this DG set been synchronized with the grid prior to this blackout event?

What protective relay or relays was the trip and blackout traced to? Differential over current? Over voltage? Under voltage?

Was it possible to subsequently synchronize the unit after the plant was restored?

Synchronizing has been explained several times on control.com. The 'Search' feature at the top of the page can be used to find references to synchronization and synchronizing and voltage matching and other terms related to synchronizing.

You should be using Internet search engines and reference sites (like wikipedia.org and howstuffworks.com and ask.com) for information on synchronization.

But, you have provided very little information in the way of how the plant has been operated in the past, and what was determined to have been the problem when this blackout event occurred.

Phase-to-phase relationships should have been verified prior to initial synchronization of the unit. Since these are mechanical connections which aren't usually easily disturbed or misconnected they shouldn't change after initial verification. However, if a recent maintenance outage was done where the main phases were disconnected and reconnected, and/or the wiring of the voltage transformers which sense the phase/frequency of the generator and bus voltages was disconnected/reconnected during the outage then these should have been verified again prior to synchronization.

It sounds like there is some kind of automatic synchronization relay or scheme being used at the site. Those can have any number of configurations so we just don't have enough information to make any reasonable guess as to how it's done at your site.

Also, some plants have very strict procedures about which breakers can be open or closed when synchronizing generator sets. Some have interlocks which prevent inadvertent synchronization; others just rely on operators to observe the proper procedures. But, again, we don't have enough information about your plant and the operating procedures at your plant to make an educated guess about what happened.

If a stranger walked up to you and asked you, "When I flipped a switch in my room, why didn't the light go on?" how would you respond? Would you begin by asking are you sure the switch you operated was for the lights? Would you ask if the switch you operated has turned on a light or lights in the room before? Would you ask if the switch was directly connected to the light fixture, or if it controlled an outlet into which a lamp was plugged and if the lamp was turned on when the switch was operated? Would you ask if the person had changed the light bulb(s) recently, or checked to see if the light bulb(s) were working? Would you ask if the fuse or breaker supplying the switch had been checked to see if it was good or closed?

How would you respond to such a simple question?