navitron
 
Renewable Energy and Sustainability Forum
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Anyone wishing to register as a new member on the forum is strongly recommended to use a "proper" email address - following recent spam/hack attempts on the forum, all security is set to "high", and "disposable" email addresses like Gmail, Yahoo and Hotmail tend to be viewed with suspicion, and the application rejected if there is any doubt whatsoever
 
Recent Articles: Navitron Partners With Solax to Help Create A More Sustainable Future | Navitron Calls for Increased Carbon Footprint Reduction In Light of Earth Overshoot Day | A plea from The David School - Issue 18
   Home   Help Search Login Register  
Pages: 1 [2] 3   Go Down
  Print  
Author Topic: Frequency shift control of diversion loads  (Read 7850 times)
heatherhopper
Sr. Member
****
Offline Offline

Posts: 347


« Reply #15 on: January 07, 2018, 11:54:18 PM »

Paul
My suggestion of a smaller turbine was a bit tongue in cheek. Our original ambition was for a 2.5kW but now wouldn't really swap the 6kW even if it is a bit oversized for a domestic set-up. If I had your generation I would dedicate one of the turbines to water heating but then we need a fair bit more than you in that department and available storage becomes the limiter anyway. Heard all sorts of clever options for storage on here and elsewhere but nothing works out both practical and cheap. I can see why you are interested in an EV. I keep looking but reasonably priced practical s/h looks a long way off.

Bigger battery bank at 48v (but no more than the capacity you have) is the future plan but will have to wait until either the current batteries and/or SIs die. Seven years old now and not showing any signs yet despite some fairly intensive treatment.

I also found that resistive heaters over 2kW firing up regularly are frowned on by the SI voltage calibration. I assumed my system being only 24v was the main cause of this but it was one of the reasons I moved to proportional diversion.
Logged

Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
Tinbum
Hero Member
*****
Offline Offline

Posts: 1178


« Reply #16 on: February 03, 2018, 12:12:27 PM »

Very occasionally it has a little glitch which I can't  quite understand - strangely it only happens when I'm grid connected. It brings the first load on and won't go back off.

Found the error- it was in the timer part of the sketch.!! Yesterday the batteries were up to full voltage, the immersion was fully on and the heaters were coming on and off. Cool
Logged

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
Tinbum
Hero Member
*****
Offline Offline

Posts: 1178


« Reply #17 on: February 04, 2018, 02:36:19 PM »


Phase Angle SSRs using a 0-10v signal from a Frequency Transducer which varies the signal proportionally (ranged 50.2-51.2 hz) to changes in the grid frequency generated by the SI.


Would it be possible to have details of the Frequency transducer you are using? Just wondering what its response time is.

I've done an adaptation to my Arduino sketch to include an outputted proportional voltage signal (within a given frequency range). When that is at maximum then frequency controlled on/off loads can come on above that range. 
Logged

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
heatherhopper
Sr. Member
****
Offline Offline

Posts: 347


« Reply #18 on: February 05, 2018, 10:51:22 AM »

Quote
Would it be possible to have details of the Frequency transducer you are using? Just wondering what its response time is.

Individual order from this range (response time is detailed in the generic datasheet):

http://www.eltime.co.uk/product.php/48/Frequency%20Transducers.html

All but one of my diversions (SSRs and on/off) operate in the 50.2-51.2 range and I try to have this maximum capacity available. With the Turbine output sustained for long periods and typically variable this is quite difficult. A PV only system I would expect to be less problem. Frequency sitting at the top of the range and close to GTI back-off is not unusual. Currently I manually intervene - in a very crude fashion.
Logged

Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
Tinbum
Hero Member
*****
Offline Offline

Posts: 1178


« Reply #19 on: February 05, 2018, 11:09:32 AM »

Thanks.

I'm wondering whats the best range to do it over. At the moment I have it very tight so they come on at 50.2Hz and stay on for 20 seconds. At the moment the loads are about 2.8kw. Hopefully I'll  soon be incorporating the heat pumps for the pool.

My wife's heat tongs seem to send the frequency a bit all over the place. I have a Comap mainspro wired up on a socket and that clicks away like mad when she's using them. Saying that it only over a small range. Strangely they are only 47w. Huh

Logged

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
heatherhopper
Sr. Member
****
Offline Offline

Posts: 347


« Reply #20 on: February 06, 2018, 11:58:44 AM »

Quote
I'm wondering whats the best range to do it over.

I suppose that depends on your overall system and aim. I guess your grid-connected situation makes for different priorities.

Quote
At the moment I have it very tight so they come on at 50.2Hz and stay on for 20 seconds.

That is tight. Even when using only on/off frequency protection relays I had them spread in series over the full 50.2-51.2 range and some with delay set.

My diversion load potential is around 9-10kW but varies a bit depending on what I have connected. Full generation potential of 8.5 kW is rarely realised (odd summer storm and then only for the peak PV period) and some of the loads are not always available hence the GTIs occasionally backing off.

I have found only one load that seriously affects frequency - a very old Braun whisk thing. Not often used anyway and I just point at the generation output and sigh resignedly at the other half when she does insist on using it. Haven't yet found any load that is disturbed by FSPC.

Heat pumps - love one and it would fit very nicely with my "difficult to get at" thermal capacity. Sadly still too expensive for me.


Logged

Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
Tinbum
Hero Member
*****
Offline Offline

Posts: 1178


« Reply #21 on: February 09, 2018, 03:33:59 PM »

Both sets of batteries got onto float today so a good test of the new diversion system.  Grin Diverting nearly 9kw.

It's working really well with the tight perimeters I have set after a bit more tweaking.

The PWM load (top immersion) comes on at 50.05Hz and is fully on at 50.35. At that 50.35 the first on/off load comes on (convector heaters) . The PMW then starts again and when or if it gets back up to 50.35 the second on/off load comes on (bottom immersion). etc etc.

It may still need a little more tweaking on the values for the load timers.

I'd also like to set it so I can switch which load is the PWM load. So for example once the first on/off load is on that then becomes the top immersion and the pwm becomes the convector heaters. It could easily be done by using all proportional control SSR's but they are not cheap especially if your using 5v control. I could use 10v ones but I would have to convert the 5v signal to 10v. I have done that in the past but it requires a convertor for each SSR.

Re heat pumps I just bought mine second hand which was pretty cheap.

Logged

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
jonesy
Hero Member
*****
Offline Offline

Posts: 843



« Reply #22 on: February 10, 2018, 03:05:41 PM »

It could easily be done by using all proportional control SSR's but they are not cheap especially if your using 5v control.
A DIY Analogue SSR
https://www.onsemi.com/pub/Collateral/AND8011-D.PDF

I could use 10v ones but I would have to convert the 5v signal to 10v.
http://www.ee.ucl.ac.uk/~amoss/java/opamp2.htm
If you have a rail to rail op-amp, you can use +/-5V. A small charge pump can provide the -ve rail.
You could use a 2 transistor common emitter amp on a single 12V rail, but this will have an offset/dead band around 0V, which might be ok.
Logged

1.1kWp PV & SB1700. 7kW log burner.
Tinbum
Hero Member
*****
Offline Offline

Posts: 1178


« Reply #23 on: February 20, 2018, 01:09:55 PM »

Jonesy, sorry I've been away for a week or so, thanks for the links.

I'm pleased to say the frequency diverter has been working flawlessly with no manual intervention at all.
Logged

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
heatherhopper
Sr. Member
****
Offline Offline

Posts: 347


« Reply #24 on: February 27, 2018, 11:02:58 AM »

Tinbum - you have managed to galvanise me into some action with the hitherto forgotten Arduino. First job for it is some independent Battery voltage monitoring but I will have a go at frequency monitoring and diversion control later. May have a question or two!
The more options the merrier I suppose but for me this is really just tinkering for the sake of it. Until spring arrives it'll be more fun than clearing the snow of the PV for the umpteenth time this year.
Logged

Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
Tinbum
Hero Member
*****
Offline Offline

Posts: 1178


« Reply #25 on: February 27, 2018, 11:29:27 AM »

I'm really pleased how mine is working. On Sunday I was diverting about 10kW.

I still need to sort out the priority of the loads but think I have solved it.

I picked up 4 Crydom MCPC2450 on that auction site pretty cheap. They are 0 -10v control signal so I have designed and am getting some PCB's manufactured to convert the 0 - 5v signal from the Arduino up to 0 -10v.

The Crydom  SSR's also have an on/off control signal so I will use that as well.

All great fun and very satisfying. Questions welcome. Smiley
Logged

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
heatherhopper
Sr. Member
****
Offline Offline

Posts: 347


« Reply #26 on: June 01, 2018, 11:54:20 AM »

Quote
Hopefully I'll  soon be incorporating the heat pumps for the pool.

Tinbum
I'd be interested in the logic you use to include your heat pumps. Although not really financially attractive for me I may try out one with an eye on the future needs must. Lots of options and complications with my system.

I am pleased you went on about the Arduino. Now have this adding battery voltage into my network - start nice and simple as they say. I may add a frequency measurement but really have enough real time data to start trying out some pre-emptive diversion with just the added battery voltage. Does mean I can drop the rather fanciful PLC from my wish list.
-
Logged

Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
Tinbum
Hero Member
*****
Offline Offline

Posts: 1178


« Reply #27 on: June 02, 2018, 11:15:24 AM »

I'd be interested in the logic you use to include your heat pumps. Although not really financially attractive for me I may try out one with an eye on the future needs must. Lots of options and complications with my system.

I vary the logic depending on the time of year.

At the moment I have it set so that the top element of the DHC comes on first. As this element is about 2.8kw once I am producing more than this the first heat pump will come on. This is about 1.2kw and set to stay on for 2 hrs.

The top element again takes up the slack until it is on continuously again and then the second heat pump comes on. This is larger at about 3kw and set to stay on for 4hrs. This is also set so that it can only go off after the first heat pump has been off for 5 minutes. It also can only come on after the first heat pump has been on for 5 minutes.

Any drop in PV output eg clouds etc can be taken from the battery bank for the heat pumps. The heat pumps are also set so they are the last items to be switched off.

It's all been working really well.
« Last Edit: June 02, 2018, 11:16:57 AM by Tinbum » Logged

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
heatherhopper
Sr. Member
****
Offline Offline

Posts: 347


« Reply #28 on: June 02, 2018, 01:14:56 PM »

Quote
At the moment I have it set so that the top element of the DHC comes on first.

DHC?
Is this your thermal storage vessel or does it refer to a wider heating network?

I assume your heat pump values are power consumption.
I would be looking to have an arrangement of timed operation but based on a predicted/assumed surplus (!!!?) with a much shorter minimum period and cut-off open-ended but triggered by a number of other criteria. With a relatively small bank I can not (and fundamentaly don't wish to have) long periods of significant draw on the batteries. 
Logged

Off grid AC coupled, 6kW Proven, 2.8kW PV, SMA SI/SB/WB Inverters, 4x576ah Rolls batteries @ 24v, 25kW Biomass Boiler, Wood Stoves, Spring/Well water. Sorry planet - I did try.
Tinbum
Hero Member
*****
Offline Offline

Posts: 1178


« Reply #29 on: June 03, 2018, 11:19:29 AM »

Sorry DHC was supposed to be domestic hot water cylinder. Embarrassed

Yes values are input to the ASHP.

Timings can easily be changed to anything and priorities. I have an external toggle switch that can turn the heat pumps off manually and other external things could easily be incorporated. I'm sure predictive could be employed from data received from elsewhere. I'm not finding i have long periods of draw from the battery but do step in sometimes and flick the switch on an evening when the sun is going down. (The larger heat pump does have a clock on it so it will switch off within itself anyway.)

My next step is to combine my two diverter sketches (frequency controlled and the grid connected controlled) so they run as one depending on if the grid is connected or not. Trying to drop the national grid frequency by bringing on loads is not to be recommended. Grin
Logged

85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
Pages: 1 [2] 3   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.20 | SMF © 2013, Simple Machines
SMFAds for Free Forums
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!