Do PV sources provide fault currents to a shortcircuit in the system?

[AggiesNM]

I have very large PV (solar) generation connected to the utility substation through an 500kW inverter and a 300V/34kV transformer. Now, for setting up the relays for coordination, I need to have fault current values. My question is: Will PV generation provide fault current through inverters, say, for a fault inside switchgear that ties the utility to this generation?

Appreciate your response.

 

[Skogsgurra]

The PV panels are not able to produce more current than corresponds to number of photons times efficiency. They are, for practical purposes - and also in theory, current sources with quite high an internal resistance.

If you have an inverter between PV panels and grid, I wouldn't worry about any more current than rated current simply because no more current is available from the panels.

If you have another arrangement, like a DC motor plus a synchronous generator feeding the grid, you will have high transient currents from the generator but not much short circuit current from the MG set simply because the PV cells, again, cannot deliver much more than they are rated for.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[davidbeach]

Unless other information is available for the specific inverter, figure that it will provide 1.2 per unit fault current for 10 cycles. They can be designed for more or longer, but will usually be able to produce less and for a shorter time.

 

[jfpe]

The inverter manufacturer should be able to give you fault current magnitude and duration. They should have it as part of the UL1741 testing. If not, I've seen a report from Sandia National Lab indicating 4pu for 1-2 cycles.
-John

 

[avc80]

I've been in the process of proving the low fault-current contributuion of PV inverters. I came across the attached papers which really helped. They show that because of how few cycles the inverter contributes to the fault for, the effect is minimal.