XW Pro and Load Power Factor?

[fred kehler]

Hi, I need help getting my XW pro to handle my house load... it can produce the power, but when the reactive power gets over about 100W I need to leave my workshop... the XW starts making too much noise... the thing is, we have lived off grid with our SW4048 running this exact same load for many years now... and were hoping the XW would be a welcome upgrade... but so far... not too sure..
our load is an inverter fridge, and 2 heat pumps, and a 1hp deep well pump... all is good when the loads are on and running... when all the loads are satisfied our real power drops to under 200W and the reactive power to over -400W and the inverter has a fit making huge humming noises...
the frustrating part is the SW inverter handles these loads with no complaints whatsoever
Schneider support has not been any help on this... except for reading the manual back to me on basic configuration...

it appears i am going to have to do some power factor correction.... trying to avoid that

is anyone else having a similar experience...?

my current setup is:
XW pro 6848 firmware v2.04bn48
SW4048 connected to Gen inputs on XWpro
700Ah LiFPo4 48v battery
connected load: inverter fridge, 12000BTU Heatpump, 18000BTW Heatpump and 1HP pump...

any comments would be appreciated..

 

[fred kehler]

Well, I have been making some progress... seems my inverter appliances are not doing enough power factor correction when in the ON but idling state... my power analyzer is showing very poor PF .25-.4 and harmonic energy around 5W at which point my XW Pro gets so noisy I have to leave the workshop or make sure enough loads are on to get the PF up again... so what I have done in the meantime, is to add the primary of an unloaded 1KVA transformer to my load, ( it calculates out ot about 1.4H inductance) this reduces my Var enough to get by until I find a more permanend solution for my fridge and 2 mini splits.. which are the real culprits... I do have a lot of electronics running as well which doesn't help the overall situation either... seems a 'whole house' PFC is needed...

 

[ElectricIslander]

It's odd that adding inductance would improve things since most household linear phase shifting loads are inductive (motors etc.) and would need capacitance added (to oppose sign of shift caused by inductance).

Does your power analyzer indicate sign of the relation between current and voltage or just the harmonic content generated by non-linear loads (ie Total Harmonic Distortion?)

I have heard similar humming from XW inverters as well.

You might just try adding some dampening to your sheet metal on the inverter. It could just be resonant vibration or some kind of magnetic coupling. I've heard of strange noises caused by errant magnetic coupling generated by too large an area between your DC cables. If you keep them close together and twist them that reduces the magnetic field generated by the DC currents needed to deal with the circulating AC currents caused by THD or other reactive power related currents.

I've also messed with making a linear filter for power factor correction but concluded it doesn't really work well since most of my loads are non-linear with THD from switching power supplies and LED's, light dimmers etc.

Interesting to see if there is such a thing as whole house PFC. Seems mostly just for large industrial applications.

 

[400bird]

I've never seen the PF displayed on my XW and the noise is pretty acceptable, but I'm normally connected to the grid.

I'd try rolling back the software, just in case the newest version you are on is causing it. Also, can you double check your build number? That's not what shows up when I check their website.

 

[ElectricIslander]

Fred - I've probably missed something somewhere along the way, but why do you have a SW4048 connected to the generator input of your XW Pro 6848?

 

[RCinFLA]

XW should be able to handle a 0.8 power factor without too much issue.

Inverter refrig is likely a rectifier-filter peak current issue but relatively low load. Its 120vac peak current is likely about 10-15 amps, with equivalent power factor of 0.6 - 0.65. I have been looking for electronic power factor correction module for my Samsung but haven't found a good 120vac module with 165 vdc output. 360 vdc output PF correction modules are readily available for 240 vac equipment but no good for 120vac refrig 165vdc inverter circuit.

A/C heat pump depends on if it is variable speed inverter model or standard induction motor compressor. If later, PF correction is relatively easy with shunt foil capacitor. Variable speed compressor in U.S. have same issue as inverter refrig but at much greater run peak current, likely in 30-50 amp range. You can get 240 vac electronic PF correction modules for that, but the higher power rating units are more expensive. Depending on size of heat pump may need about 3-4 kW PF correction module. Many 240vac mini-splits have the PF correction module as it is required for EU regulations. Some models leave it out for U.S. market units to save on manufacturing cost.

Pumps and air compressors usually have just starter capacitor with centrifugal cutout switch after motor spin up. They have poor run power factor in 0.7 ballparks. A proper sized run capacitor between main and start winding will improve run power factor of pump and shunt foil run capacitor across mains can improve it further.