Inverter generation is increasing significantly. The traditional protection schemes in distribution circuits are not well suited to locating faults where there is no overcurrent. What approaches have been tried and what are their success rates.
In a MicroGrid, a fault does not increase the inverter output but the output voltage is reduced and this is the only indication of a fault but the entire network sees essentially the same voltage. The fuses and other overcurrent devices likely are challenged to be able to isolate the faults so it seems that a trial and error approach of circuit isolation and restoration is the best method at this time.
Comments on approaches that have been tried with their effectiveness is most appreciated.
Current waveform analysis in both time and frequency domain is often followed.
Fault current the low power factor current could be discriminated even at load value from normal load current…..
I agree that they can be detected this way. More of what I am looking for is how to determine the fault location so that other breakers/reclosers along the same circuit do not trip thus leaving only the one closest to the fault to operate. Are there any thought on this?
To my knowledge the problem to determine the fault location in a microgrid with small distances is not really solved. Not only to distinguish protection zones along one line, but also to distinguish faults in parallel lines could be challenging. We have an idea involving PV (or other) inverters as sensors, but it's not yet thoroughly investigated.
Dear Joe Rostron :
I hopr you're doing well.
Pls have a look at these research papers. It will help you for sure.
https://www.iitk.ac.in/npsc/Papers/NPSC2016/1570293954.pdf
https://www.mdpi.com/1996-1073/12/23/4504
Regards;
Ehtisham
Ehtisham, Thanks for these papers. More specifically, I am looking for techniques where the fault current does not rise because of the output current limitation of the inverters. Overcurrent based techniques are well established but undervoltage while maintaining prefault current levels in not a normal protection relay function in Distribution circuits of 38kV and below. It would be most appreciated if such techniquies are available.
Regards, Joe
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