Effect of Non-linear loads on DG SET

[deeveeyes]

WE HAVE COME ACROSS A CASE, WHERE A 1250 KVA, 415V DG SET IS NOT ABLE TO TAKE THE LOAD OF 2 DC DRIVES EACH RATED AT 500 KVA. WE HAVE BEEN TOLD BY DG SET MANUFACTURER THAT IT IS DUE TO HARMONICS PRODUCED BY DC DRIVES. THE DG SET IS 415V AND SUPPLY TO DC DRIVES DIRECTLY WITHOUT ANY TRANSFORMER IN BETWEEN. CAN SOMEONE EXPLAIN THE REASONS FOR THIS ? WILL INSTALLING A HARMONIC FILTER ACROSS THE DRIVES HELP THE SITUATION ?

 

[jbartos]

Suggestion: Interpreting the DC drive as an AC to DC conversion, the traditional six-pulse (simply: six diode full wave) rectifier without any harmonic mitigating scheme (e.g. filters, power line conditioners, etc.), the harmonics produced on the inputs side may be tripping the generator protective relaying sensitive to the harmonic content (e.g. negative sequence relays). Installing harmonic filters will help. Also, the better AC to DC conversion, e.g. Active Front End, which includes controlled rectifiers, will help.
Head on start: There are some useful postings in this Forum, which can be searched for, e.g.
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