Are inverter based renewables making it difficult to protect transmission lines? 1

[George556]

I’m a protection engineer at a utility in California. Do you think a lot of traditional synchronous generation is going away and being replaced by inverter based resources like solar? The new renewable resources don’t contribute fault current and die down after a few cycles.

Do you think we will be in a situation in the future where we wouldn’t be able to detect faults with distance and overcurrent based relays because the fault duty will be too low to pick up fault detectors?

Should we start putting current differential schemes everywhere to be more sensitive? Should POTT be eliminated in future relay upgrades?

Our philosophy on our 230kV is to have one current differential relay with diff and backup distance/overcurrent elements and another backup relay with just distance/overcurrent elements.

 

[davidbeach]

In answer to the thread title question - Yes.

Differential will definitely work better in an IBR (Inverter Based Resource) environment than distance as we know it. Traveling Wave may turn out to be even better. The industry needs a bit more operational history to garner a better understanding.

 

[sushilksk]

Solar power is intermittent, traditional generators will be there to support it, however there percentage is going to reduce. For radial feeder from solar, current diifferntial may be better or distance with week end infeed is other option.

For ring connected solar inverters, we may get sufficient fault current for distance protection.

We have to think about requirement / relaibility of optical connectivity also.