New to solar and this site and a little problem to solve with my generator

NorthernBoy1

Thank you for the welcome, I live in northern Europe 60 degrees north so not much sun here at this time of year. I have just installed an off grid/on grid system on 3 phase and wanted to say hi, introduce myself, share my experiences, issues and hair tearing out moments. We are now up and running with a 3 phase solar inverter, 20 PV panels, 3 Inverters/chargers (one for each phase) 200amphour battery bank at 48 volts and a 4KW 3 phase portable generator that wont work. And its the gen set that has got me here to start with. Happy to share my experiences as and when I can, I have learnt a lot and lost most of my hair in the process.

Generator works the house when isolated from the solar system but the lights flicker. Our inverters are sensitive to voltage input 180-265 volts and need hertz of 45-65. I tested the voltage and got a reading of 277 at the charger so slowed the generator to get 250 volts but I don't know how to test the frequency.  Basically it all works fine on grid and off grid but when I switch over to the generator it is not recognized.

Any thoughts?

littleharbor2

NorthernBoy1, welcome to the Forum.  Being in Europe and with the electrical system you are using, hopefully there are some members on the forum that are familiar with this format. My limited familiarity with this format will keep me from commenting other than one question. Is your generator input going into the correct AC in on your inverter/charger? Typically there are two inputs, one is intended for grid AC and the other is for generator input.

Graham Parkinson

Hallo Northern Boy!  60 Degrees north is quite a bit further north than our 50 degrees here in Canada.

Generators are usually controlled in their voltage by adjusting the regulator, not by their speed.  Some generators have capacitors in their regulator that set the voltage.  Usually the frequency is controlled by the speed as that sets how fast the poles go past the windings, slowing the speed will lower both the frequency and the voltage.   You can get cheap multi-meters that measure frequency as well as voltage.

What kind of generator do you have?  Is the flickering under load or even with just light loads?  Lower quality generators often have dirty waveforms that make LED and fluorescent lights flicker.

Picture looks like Norway so: Med vennlig hilsen 

mike95490

Usually, the generator frequency needs to be closely regulated, and there is a wider voltage range.  Get a meter with frequency reading and see if you can get the generator set to fall inside the voltage and frequency windows.

NorthernBoy1

Thank you for your comments, a Hz meter is on my list. My meter only offers voltage. Once I see what the Hz is i will know a little more.

The LED lights flicker even under a light load of say under 50 watts.

All our lights are LED and we heat by wood both the house, cooking and water. Normal winter usage is about 6KW per day, quite low, just the fridge, water pumps from wells and one small water heater for hot water in our kitchen.

The feed is either grid/off/generator using the same input and feeding three Victron MultiPlus 48/3000/35 charger/inverters as we are on 3 phase. Local grid is 230v 50Hz and we have 20A per phase on grid.

The generator is a strongline MEG4000, Yamaha engine.

If the Hz and Volts need correcting I will take it back to the retailer as its under warranty.

I understand that it is possible to put a (something, no idea what) between the generator and charger/inverters that will smooth out the output.

I am not an electric expert and probably know just enough to do more harm than good!

Norway is close Graham, we are a little further east but still in Europe.

Graham Parkinson

My LED lights flicker on my old fashioned Honda EX650 generator but not on my Ryobi propane inverter generator.  I find that dimmers plus LED lights on dimmer circuits are the most sensitive to having the frequency off spec.  The flickering was much reduced once I tweaked the frequency to the 60 Hz that the North American dimmers were expecting.

Some generators need a resistive load to dampen the ringing caused with light inductive loads.  Worth putting a resistance heater on just to test to see if the flicker goes away with resistive load applied.   You might try asking more knowledgeable people on the excellent Smokestak generator forum for help with understanding generator issues!

petertearai

The little power meters that you plug into your power point to measure usage often include a frequency read out .  They are handy . ., and fairly inexpensive.

mike95490

a 3 phase voltage stabilizer is going to be pretty pricey.  You are likely better off getting the generator serviced to spec, and widen the acceptance window on the inverter
https://www.ashleyedisonuk.com/voltage-stabilisers-660/ 

NorthernBoy1

Good afternoon from here and thank you for your messages, been snowing so its very pretty but solar output a little low!

So the generator, I bought a better multi meter and connected up the generator to the system. Grid 230v and 50Hz on all three phases. Generator 265v on all 3 phases and Hz Phase1 320-370 range; Hz Phase 2 165-200 range; Hz Phase 3 265-320 range.

Is that weird or not?

BB.

Are you reading your AC voltage from L1 to L2, L2 to L3, and L3 to L1? Or you are you measuring from Neutral to L1/L2/L3?

Do you have a Link/wiring diagram for the genset?

-Bill

NorthernBoy1

Hi BB and thank you for your message. I am measuring Neutral to L1/L2/L3 I am hoping to get close to 230v being our local Grid voltage. My chargers require....

Standard MultiPlus factory settings
Inverter frequency 50 Hz
Input frequency range 45 - 65 Hz
Input voltage range 180 - 265 VAC

But its the Hz output that worry me, I have little knowledge on this stuff so a bit stuck.

I do not have a Link/wiring diagram.

BB.

It sounds like the Generator may be "Delta Wound"... If so, you will see different voltages between Neutral and Lx's. A bit of discussion about Wye (or Y or Star) connected vs Delta wound/connected:

https://www.physicsforums.com/threads/delta-vs-wye-pros-and-cons.682676/

From the above (last post) is a nice paper on 3 phase power:

http://apps.geindustrial.com/publibrary/checkout/GET-3388B?TNR=White Papers|GET-3388B|generic

Note, normally Wye connected generators and transformers have the center tap of the Wye grounded (and Delta may have a center tap of one of the windings grounded)... If the tap is not grounded (effectively creating a neutral), the "N" to Lx voltages may float/vary (based on your loads and any parasitic AC or DC current paths to ground).

3 phase AC off grid power systems can be very complex... Details matter (generator and load types/connections). And for larger/complex systems, sometimes even power engineers make mistakes.

-Bill

mcnutt13579

The Hz reading on your meter is wrong.  There is no way a generator can put out that kind of frequency.

The generator puts out one cycle per revolution.  So if it is running 3000 RPM then it should be putting out 50 Hz.

I think you need to buy a better meter.  Here in the US we trust Fluke.  I don't know whether that is available in Europe.

BB.

I guess I have missed the "measured" line frequency of the Genset (Hz  or Hertz--AC Cycles per second). All I see is the 50 Hz inverter related specifications.

-Bill

NorthernBoy1

Grid 230v and 50Hz on all three phases. Generator 265v on all 3 phases and Hz Phase1 320-370 range; Hz Phase 2 165-200 range; Hz Phase 3 265-320 range.

BB. Readings are above.

mcnutt13579. readings using same meter, using same process, neutral to line. Readings are correct and as expected from grid (tells me meter is working) readings from generator as above. I did this three times over an hour. the readings are from the switchover switch where both the grid and generator can be switched between Grid/Off/Generator. No loads on either as switched to battery back up so lines were blank.

I am finding all this hard to understand. My thoughts are the generator is putting out too high Hz but mcnutt13579 appears to think that's not possible.

I am becoming a little lost here! But hey that's life.

BB.

Those appear to VAC readings, not Hz...

A 1,500 or 3,000 RPM genset would have to run at ~6x normal RPM (9,000 or 18,000 RPM) to generate  ~300 Hz. A 50 Hz genset running at that RPM would not be long for this world. (all things being equal).

Also, the Hz reading has to be the same for all phases (there is only "one frequency" from a 1 or 3 phase genset or utility power). A "reasonable" Hz (frequency) reading from a 50 Hz genset would be something between 40-60 Hz (if the motor RPM was anywhere near correct). And many mechanically governed gensets "should be" at worst, 50 Hz +/- 5 Hz. At best, probably +/- 2 or 3 Hz for a typical genset.

If you are actually reading that frequency, I would suspect either the meter has something wrong or the AC output of the genset is seriously broken.

-Bill

mike95490

Many generators produce a strange output waveform when unloaded or heavily loaded.   Put a couple hundred watts of load on each phase, and then see what the Frequency is.     The frequency is controlled by the RPM, and must be in the 50 hz range, or else the speed adjust is dangerously wrong and the engine or generator can "grenade" from internal centrifugal forces

NorthernBoy1

I think I am beyond my self here. The Generator is quite new so I will get it checked by the shop I purchased it from.

My issue, that i don't understand is the chargers work on grid supply and not on generator supply. I am baffled by this situation.

Thank you for your input, I have learnt a little and that's always good. Will keep you updated as and when I have any news/progress.

Estragon

Is this an "inverter" type of generator, or conventional?  When I searched, it looks like they may sell both types.

An inverter type will vary speed with load, saving fuel and running quieter with lighter loads.  They have electronics inverting internal DC to the AC output, and I'm wondering if there's something gone wrong there, or maybe a stepped output waveform confusing the meter?

NorthernBoy1

Estragon: I think its just conventional and governed manually, I adjusted the spring to bring the rpm down to reduce VAC from 277 to 250.

Mike 95490: Thank you, I am just lost now in how to sort out the problem below.....

My issue, that i don't understand is the chargers work on grid supply and not on generator supply. I am baffled by this situation.

BB.

Get some help from the shop--And maybe even a little instruction on confirming basic functions (volts/amps/frequency/rpm/etc.).

Generally, you adjust RPM for frequency, and output Voltage via the voltage regulator (some are fixed output regulators and would need servicing to "adjust" the output voltage). Placing some sort of load (very roughly 100 watts per leg minimum--Or small electric heaters/load bank... Avoid "active loads" like computer power supplies--Many have "very difficult" current waveforms for gensets/inverters to drive) on the Genset can help stabilize readings.

A couple of links from this post:

https://forum.solar-electric.com/discussion/comment/358047#Comment_358047

http://www.screenlightandgrip.com/html/emailnewsletter_generators.html
http://www.screenlightandgrip.com/html/emailnewsletter_generators.html#anchorSquare Wave Generators

-Bill

Estragon

My understanding is changing RPM will change frequency, as each rotation will result in 'X' cycles (with 'X' depending on the number of poles).  I think voltage adjustment would be done in another way, likely somewhere in the alternator control wiring.

The inverter/charger has a (sometimes adjustable) range in which it will qualify/drop generator input.  Some also have a delay time for warm-up, maximum total current, and/or maximum charging current which might be worth checking in case one of these settings got pooched somehow.

My understanding is pretty rudimentary though, and I'm not familiar at all with that generator brand, so FWIW.

mcgivor

The reduction of rotational speed of the alternator will have the  effect of lowering output voltage, however the corresponding result would be  a reduction in frequency. Given that the rated output is 277/380 V the option to change this to 230/400V 50 Hz European grid standard, depends on the wiring opinions within the alternator, not on the governed speed, another option is through the use of a transformer, to correct it to values required.

My suspicion is the unit would first be unqualified due to over voltage, the consequent adjustment of rotational speed altered the frequency outside of frequency qualification range. It was stated the voltage is now 265V with strange and impossible frequency numbers, the voltage may still be too high as the RMS value has some margin of error on virtually all multimeters, reducing speed further, would only result in further frequency reduction. 
https://engineering4uu.blogspot.com/2017/04/speed-and-frequency-of-synchronous.html

Graham Parkinson

Just to explain the concept of "Frequency" - A waveform can be a superposition of many frequencies.  A perfect and endless sinewave has only one frequency, the "fundamental". In your case this would be 50 Hz in your case. 

An actual dirty generator waveform (with harmonic distortion, spikes, variability) has many "frequencies", with additional frequencies going along for the ride that make up the distortions.  Usually the main extra frequencies seen are the "harmonics" such as doubles, triples etc.

Depending on the meter's frequency response, meters can latch onto these other frequencies, many of these frequencies can be higher than 50 Hz and this may explain your strange measurements.  You should try your meter on the inverter outputs and other sources, read the manual in detail and become familiar with how it works and responds.

Generator waveforms can have low frequency clipping off of the peaks at high loads and high frequency ringing at low loads, both of these will overlay extra frequencies onto your waveform.

Faulty regulation can also make for strange effects and problems like flickering lights.  I bought a cheap "DSO Nano" credit card sized digital oscilloscope for $100 - Best investment in understanding off grid power troubleshooting ever!

These handy little scopes have a frequency meter mode and have waveform analysis/measurement modes.  They are a great thing to have to measure, diagnose and help you fix strange generator/inverter behaviors.   Tested a neighbour's near new Yamaha inverter that was burning out expensive controls on his pellet barbeque.  It was shocking to see the spikes that were coming out of his generator waveform.

mike95490

A engine driving an alternator, creates a sine wave
https://www.electronics-tutorials.ws/accircuits/sinusoidal-waveform.html

and the engine speed controls the frequency of the sinewave.   So engine speed at no load needs to be set to generate about 51 or 52 ( or 62Hz, depending on your electrical gear) Hz and as the load increases, the engine governor attempts to maintain the desired speed, but often looses a Hz or 4.

BB.

Boy--I am very tempted to buy Graham's suggested DSO Nano scope...

Just be very careful before attaching your O'scope to your AC Mains. Most "laboratory scopes" are not setup to safely make arbitrary connections to 120/240 VAC mains (i.e., lots of smoke and tears).

-Bill

Graham Parkinson

Good point BB.  

Lab type scopes powered by 120 VAC may have their reference ground input tied to AC neutral or ground so you have to be very careful where you attach the probe ground to avoid shorting line to ground.

Portable internal battery powered instruments like the DSO Nano V3 series scopes are floating on both inputs.  This is both a blessing (makes connecting less problematic) and a potential danger.  When you connect them you have to be aware that in the event of a fault the case may take on a voltage somewhere between line and ground.  Very happy with these little scopes though. They seem well made by Seed Studios and are open source too.

Forgot to mention that for use on 120 VAC you need to make or buy a 10:1 probe as the DSO scope has a maximum 10 V/division full scale range (i.e. about a 100 V range) and you may need a BNC type connector adaptor for the probe as the scope comes with a set of micro circuit clips on a small headphone type plug.  Alternately you can make your own voltage divider probe with a 10 to 1 ratio attenuation circuit of appropriate 50 k / 500 k resistors or with  20:1 ratio (for 230 volt folks).

NorthernBoy1

Thank you all for your input and helpful information, generator gone back to shop to be checked and I will let you know what happens, whenever it comes back.

mcgivor

Have you questioned the voltage issue? Standard voltage should be 230/400V European standard, not 277/380V

NorthernBoy1

mcgivor: we have asked that the voltage should be 230/400 and that the RPM should be set to give us 50Hz. we explained all our issues, handed it over and can now just trust the process!

mcgivor

Best of luck, I'm sure once the voltage and frequently issues are corrected it should work as intended.