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Lucian Popescu (Victron Energy Staff) avatar image
Lucian Popescu (Victron Energy Staff) posted

Send surplus power to a boiler using a variable solid state relay

When the batteries are full, we still have pv power available but our grid operator doesen't allow feeding or we have an offgrid system, that power is lost. We could use that power and send it to a boiler or something similar.

I'm testing 2 types of relays that ca be externaly controlled in order to reduce or increase the power transfered. The relays are Anly ASR-40RA and Anly ASR-40CA. The first one, can be controlled by modifyng the resistance on the input contacts (0-250K), the second one can be controlled using curent (0-20mA).

Now the results:

- the first one is cutting the sinewave from the begining


- the second one, cutting the end


Now some real test on a Multi 800 with a 600W load can be found here:

https://www.dropbox.com/s/ome3jdthik2jf7o/2019-03-18%2013.28.25.mp4?dl=0

The behavior is similar on both relays, the inverter is poducing some noise, lowdest when the power is around 50%



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ossi avatar image ossi commented ·

HI

really interested in solutions for own consumption optimization with thermal storage.

Looks like a good solution sofar, let me add perhaps some comments from my side:


First let me add, that i really don't like the phase angle control since it is messing up the Sine Wave.

I would prefer either the solution of having Heating rods connected to the DC side for DC coupled Solar and switching them On by increment (200W+200W+200W).


Or for AC Coupled Solar System a Heating rod connected to a PWModulation of the output voltage (e.g. My-PV or Fronius Ohm pilot or Solar fox). Advantages longer lifetime of the Battery Inverter.


For Offgrid System (AC Coupling or adjustable output frequency) it is very easy to realize, since the Frequency shift control, is providing a communication on the AC Bus already which can be used without any additional control (when frequency rises above 52Hz start dumping energy into the Thermal storage)


BR

Oliver

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Pat Davitt avatar image Pat Davitt commented ·

I headed in the same direction your are, except I going to try out a Crydom PMP2425W Proportional Relay. My post in "Mods" is:

https://community.victronenergy.com/questions/7170/calculating-and-controlling-excess-pv-power.html

Should be fun.

Pat

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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ Pat Davitt commented ·

Hi Pat, i'm looking at the datasheet for that relay and it has 2 ways for the output, phase angle controll and burst fire. The first one is doing exactly the same as in my tests. I'm curious about the second one. Have you tested it with Victron inverters?

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Pat Davitt avatar image Pat Davitt Lucian Popescu (Victron Energy Staff) ♦♦ commented ·

Lucian,

The Burst Fire is what intrigued me. Should be cleaner since it's pulsing full cycles. My relay won't be delivered until Thursday so will have wait and see.

Pat

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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ Pat Davitt commented ·

please share some oscilloscope screenshots

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Pat Davitt avatar image Pat Davitt Lucian Popescu (Victron Energy Staff) ♦♦ commented ·

Funny you should mention O-Scope screenshots. Since I retired I do not have access to an EE Lab. So, I have been online researching scopes trying to find one I won't have to mortgage the ranch to purchase. Thinking of getting a 2 channel 50 Mhz, Pico Scope MSO with a high voltage differential probe and a AC/DC clamp Amperage probe.

Do you have any opinions on Pico Scope products?

Thanks,

Pat

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Pat Davitt avatar image Pat Davitt commented ·

Success, so far. Got my PLC Ladder program finished and it is passing the correct values to my analog output. Tomorrow I am going to install the relay in the system and "smoke test" it.

My new O-scope stuff should arrive on Monday and, once I figure out how to use it, I can send you some screen shots of what's really going on.

Pat

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Pat Davitt avatar image Pat Davitt commented ·

Lucian,

Got the Crydom Proportional Relay hooked up and ran my PLC program. Everything worked as expected. I used an incandescent light bulb as my load. I can see why Burst Mode is not recommended for lighting. At the lower amperage settings the lamp flashed like a strobe, it settles down at higher settings. Going to see if I can find an old style radiant heater, to see how it works with a higher amperage load.

Burst Mode should work fine for a heating element.

Can't wait to get my scope on Monday and see what the Phase Angle and Burst modes really look like and how they may effect my Quattro.

So far, so good.
Pat

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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ Pat Davitt commented ·

Hmm, in this case I'm pretty sure that when the duty cycle is low and you have a boiler connected to your relay, you will see the light flickering. in your house.

So probably the other method (phase angle) is better.

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Pat Davitt avatar image Pat Davitt Lucian Popescu (Victron Energy Staff) ♦♦ commented ·

Lucian,

Not ready to admit defeat yet. Get my scope tomorrow and I have some empirical testing yet to do.

Been doing this for about 40 years and nothing surprises me anymore.

See my favorite T-Shirt below. :-)

Pat

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Pat Davitt avatar image Pat Davitt Lucian Popescu (Victron Energy Staff) ♦♦ commented ·

Lucian,

Got the scope hooked up and I am not sure what to make of what I see.

In the scope shots below Red is the Voltage waveform and Yellow is the amperage consumed by the load.

The proportional relay was set to burst control.

First shot is the voltage at the load, measured from hot(L1) to Neutral, and the load amperage.

The second shot is the voltage at the AC Source, measured from hot(L1) and neutral, and the load amperage.

Pat


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Lucian Popescu (Victron Energy Staff) avatar image Lucian Popescu (Victron Energy Staff) ♦♦ Pat Davitt commented ·

Hi Pat, Nice t-shirt :)) What kind of load are you using?

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Pat Davitt avatar image Pat Davitt Lucian Popescu (Victron Energy Staff) ♦♦ commented ·

Lucian,

It was a very light load. Have got to get a much higher watt, resistance load and see what happens when the system is under more stress. Hopefully I will get that done today.

Pat

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Pat Davitt avatar image Pat Davitt commented ·

Lucian,

Finally got my scope and probes setup correctly. Hopefully the data makes more sense. I added a measurements section at the bottom of the screen. The parameters of the test were:

1. 1320W IR Heater load.

2. Relay set to 12.5A output (50% of rated power).

Pat

Burst Mode Voltage measured at Load

Burst Mode Voltage measured at Source

Phase Mode Voltage measured at Load

Phase Mode Voltage measured at Source

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