I have a power system where on some buses, large converter driven machines result in high harmonic distortion. As far as I know, there are mainly two ways to reduce the harmonics.
- A filter to remove (reduce) unwanted harmonics within a range of frequencies
- Reactors to create a smoother wave form.
I'm wondering what are the pros and cons for the two alternatives, and are there any other (better) alternatives? I cannot change any of the existing equipment, but I can add equipment (criteria: smallest size then lowest cost). The converters are 6-pulse rectifiers without filtering, and cannot be substituted (12-pulse would typically give a smoother wave).
The filter will only reduce some harmonics, and I have problem with the 5th, 7th and odd harmonics between 25-37th. I could design a filter to reduce the higher order harmonics, but then I would be stuck with the high 5th and 7th components. (Or have a filter to remove the 5th and 7th, leaving me with the higher order components).
Reactors seems like the best approach, but almost all similar systems I've seen have filters. The size and weight must be as low as possible (even if that might increase the price of the equipment).
The equipment rating is in the range 800-1500 kVA and I have THD above 10%. There are no resonance frequencies in the network (the lowest is around the 180th harmonic).
Is one of the approaches generally better than the other. Will there be any significant difference in size for the two?
I hope someone has any views on this. Thanks!