"vector shift relay" or "rate of change of frequency relay"
"vector shift relay" or "rate of change of frequency relay"
(OP)
Hi everyone,
There is a cogeneration plant synchronized with the grid and there is coupling circuit breaker for connection to grid.
When grid further breaker opens, we want to trip the coupling breaker.
Which one of "vector shift relay" and "rate of change of frequency relay" can overcome this protection, or two of them?
Thanks in advance..
There is a cogeneration plant synchronized with the grid and there is coupling circuit breaker for connection to grid.
When grid further breaker opens, we want to trip the coupling breaker.
Which one of "vector shift relay" and "rate of change of frequency relay" can overcome this protection, or two of them?
Thanks in advance..






RE: "vector shift relay" or "rate of change of frequency relay"
M.A.Sh.
Elect. Engr.
RE: "vector shift relay" or "rate of change of frequency relay"
ice
RE: "vector shift relay" or "rate of change of frequency relay"
RE: "vector shift relay" or "rate of change of frequency relay"
ice
RE: "vector shift relay" or "rate of change of frequency relay"
An inter-trip is not appropriate because a loss-of-grid condition may occur as a result of numerous possible breaker trips and it is unrealistic to arrange an inter-trip from every breaker. Additionally not every breaker would necessarily require the embedded machine to trip in every circumstance, so the tripping logic would be come enormously complex.
RE: "vector shift relay" or "rate of change of frequency relay"
Once the grid shuts down, does any vector shift appear with generator voltage?
Somewhere I read that ROCOF relay is better for this situation
RE: "vector shift relay" or "rate of change of frequency relay"
Regards
Marmite
RE: "vector shift relay" or "rate of change of frequency relay"
RE: "vector shift relay" or "rate of change of frequency relay"
Generator will remain connected servicing the site load.
RE: "vector shift relay" or "rate of change of frequency relay"
I can't help, I'm not familiar with either of the two relays. However, I watch over two plants with generation as well as a utility connection - so I'm very interested. So, a couple of questions that will make it easier for me to follow:
1. Does your plant always import power from the grid? Always export?
2. Are there operating scenerios where there is no power transfer across the grid connection CB - just floating - probably only for short periods?
3. When the grid goes down, is it normally open circuit (their CB direct to you opens)? Or short circuit (they open the line way up stream)?
ice
RE: "vector shift relay" or "rate of change of frequency relay"
There are a few multifunction relays that include both protection elements - I have used the Alstom P341, but there is one from Basler and probably others too.
We use both elements of this relay on our generator tie circuits.
RE: "vector shift relay" or "rate of change of frequency relay"
Voltage shift is faster..about 40ms, ROCOF about 100-120ms, but voltage shift in not easier for setting.