Destructive Harmonics Mitigation and recyclingback to useful energy

Stop listening to snake oil vendors / perpetual motion salesman. Harmonics are not energy. They are a distortion of the waveform. They behave like bad power factor. You cannot turn 10KVAR of lagging power factor into 10KW even with power electronics converters and even less with any type of passive transformer.

Most harmonics are caused by large non sinusoidal loads connected to 3 phase power. Things like switching power supplies and electronic ballasts. This usually requires considerable up sizing of the neutral wire and special harmonics rated transformers. Prevention is pretty much the only way do deal with this type of problem. Do you have any idea what is generating these harmonics?

Guest,

As stated in replies already submitted harmonics on power network are generated by non sinusoidal loads such as switching power supplies, inverters, and variable speed drives.

I am sailing as Chief Engineer on a ship employing SCR drives to power 2- 2150 HP propulsion motors. Harmonics are a significant problem.

SCR ships service AC to variable voltage DC is accomplished with a 12 pulse converter, creating significant 5th, 7th, and 11th order harmonics.

Solution is filters consisting of 3, series L-C circuits tuned to the 3 harmonic frequencies providing a low impedance path for the harmonic components back to the source (SCR Drives) through a resistor network to be dissipated as heat.

Additionally the large Capacitors (2400 KVA's worth) adsorb a significant amount of reactive power created by ships fluorescent lighting, and propulsion motor inductive reactance, improving power factor to somewhat better to .9, I have plans for additional correction, as reactive power does o useful work, but consumes fuel.

You are asking about 3rd, and 5th order harmonics, therefore I assume you have a 6 pulse rectifier drive system, therefore you need filters tuned to 3rd and 5th harmonic frequencies.

Perhaps rather than dissipated as heat the energy could be recovered as DC for battery charging, could introduce other problems.

Only application I know of for ZigZag transformer connections is for three to single phase conversion, and phase shifting, any other applications, I would certainly like to hear about.

Regards

CEKM