Hi, Kali,
The information you have provided is very sketchy and makes it extremely difficult to provide good and pertinent comments.
As a general statement, you mention a substation with 25 THD. Is the THD measurement for voltage or current? If that is a THDv measurment, then you may have real problems. If that is a THDi measurement, then you may not have a problem.
If you are referring to a substation, I would expect the current to be much greater than 10 amperes as stated. For a substation 10 amperes is almost nothing.
Something to think about is that 10 amperes is a very small load. Depending upon the source rating (short circuit amperes – ShCA), the THDv should be almost 0% (1-2% would be typical background noise). If the ShCR (Short circuit ratio: ShCA/fund amental current of load) is very high, the THDv would be extremely low for a 10 amp load with 200% THDi.
Much more information is needed to better understand your situation. But I can say with much conviction that a 10 amp load is not going to be a problem….
Regards,