I live in an off-grid home. I have an PV system and a 16KW commercial generator (1800rpm / 4 cylinder/ 4 pole Rotating Field, Brushless, Electronically Regulated ) . I noticed that when I run the generator a few of my LED light bulbs flicker at a high rate. After much research, I found the issue to be Harmonic Distortion. The Total Harmonic Distortion in the system goes up significantly when the generator runs. Voltage and frequency coming from the generator are near perfect at 120 +/- 2 volts and 60Hz +/- .4Hz. However, THD goes from under 4% to about 12 -13 %. I tried connecting the generator in bypass mode and shutting off the PV inverters. I found that THD remains under 4% when just running all the loads in the house on the generator. I believe my issue is the non-linear loads created by the Inverters’ battery chargers which are converting the generator power from AC to DC voltage. When the generator runs, the inverters' battery chargers draw 56 amps AC to convert to DC voltage used to charge the batteries. Does anybody know of a solution to this problem? Is there something else to look at other than THD to assess the distortion, i.e. is it really a problem that may result in damaging devices in the power network or just an annoyance....
Also - I am confused by THD ratings on generators and my inverters. It seems to me that THD is a result of the non-linear loads in the power system which can vary a great deal. So how can a generator or inverter carry a rating for THD% without knowing the particulars of the power system. My THD generally remains below 3% running off the inverters, but it goes up to 7% or 8% when my RO system (which has a 5HP motor driven by a VFD (another source of non-linear loads)) running. It's rated THD is typical - 2% Maximum -5%. But in my real world system its going higher than that so how can you put a limit on THD without adding something to the power system that will compensate for the non-linear loads.
Also - I am confused by THD ratings on generators and my inverters. It seems to me that THD is a result of the non-linear loads in the power system which can vary a great deal. So how can a generator or inverter carry a rating for THD% without knowing the particulars of the power system. My THD generally remains below 3% running off the inverters, but it goes up to 7% or 8% when my RO system (which has a 5HP motor driven by a VFD (another source of non-linear loads)) running. It's rated THD is typical - 2% Maximum -5%. But in my real world system its going higher than that so how can you put a limit on THD without adding something to the power system that will compensate for the non-linear loads.