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62
General Discussion / Re: Welcome to FieldlinesForum! Your new Community.
Last post by Xeonpony -
Glad to see the name resurrected, but I still lament of all the lost members from old that shall never be seen again! Hopefully some how you can get the data from the old forum

When I have more time I'll help fill a few sections up, my ewe lambed so have very cute pictures for the farming section.
63
Wind Power Machines / Re: Interfacing wind turbines to the grid
Last post by MaryB -
Quote from: SparWeb – on
Quote from: Bruce S – on
This looks to be a nice setup, like BRCM I'm curious where you go with these.

Well, slowly, is where I'm going.  Diving into the circuits, I'm afraid of how choppy the signals are to monitor current.  I'm adding various things to smooth it out, so that I don't need a complicated program in the software.

Feed it thru a rectifier and monitor the DC current via your micro... a full wave bridge with electrolytic has 1.4 times the voltage output so some math involved...
65
Wind Power Machines / Re: Interfacing wind turbines to the grid
Last post by Bruce S -
Quote from: SparWeb – on
At this point, the ideas I'm sharing are partly based on a device I developed with Glen Hurd (aka GHURD) from the old Fieldlines board.  He deserves credit for doing a lot of development work to make a similar device work, which I built and used for years.  It was called an "opportunity diversion load timer", which "sniffed" when the charge controller was running the diversion load, and switched on some kind of DC or AC load that could be used instead.  While the AC or DC load was running, the batteries were being drained thus the need for a diversion load by the charge controller was relieved.  So instead of running a heater in my garage, a heater kept water for our horses thawed in the winter.  This saved me a lot of money and this device paid for itself quickly.

I just wanted to pause and give a shout out to GHURD, wherever you are.  Your ideas live on and I'm still using them.
SparWeb;
He's still kicking. I have a few conversations with him and Tom W, from time to time.
I still have the ones I purchased from him too. I'm currently redoing my little 200Watt solar setup to try out a smallish sand heater setup for our basement media/playroom.
 This looks to be a nice setup, like BRCM I'm curious where you go with these.

Cheers
Bruce S
66
Wind Power Machines / Re: Interfacing wind turbines to the grid
Last post by SparWeb -
A bit more explanation of how the circuit works:
  • Detects when the Charge Controller activates the diversion load resistors by sensing voltage, then closing the relay contacts. Otherwise, this device is dormant and the relay is Open.
  • Once triggered, the device closes the relay, and stays active for a pre-set time, then shuts off.  If the Charge controller is still running power through the diversion resistors, then the device triggers again for another cycle.  The activity cycle can be adjusted.  Let's assume between 15 minutes and 1 hour, for now.
  • The relay only supplies + battery voltage to the DC positive terminal of the microinverter. 
  • The DC negative terminal of the microinverter is grounded through a pair of power resistors, totaling 4.5 Ohms.
  • Even so, the microinverter should begin to activate as soon as the relay closes.  At first the microinverters will not pass any DC current, just measure DC voltage, so it won't see a voltage drop across the power resistors, yet.
  • Microinverters always have a 1- or 5-minute delay before they actually connect to the AC, so the device will just wait in the meantime.
  • While waiting, the gate driver is already active.  What it's doing is cycling the FET on and off across the 4-Ohm power resistor.  I'll explain the reason for this later.
  • Once the Microinverter comes on-line, it will simultaneously connect to DC, admit current through the DC lines, connect the AC output lines, and  start seeking the MPPT point.  Since it's pulling DC through some power resistors, it will detect a voltage drop.
    This is intended because solar panels have a strong voltage drop while current increases.
  • Unfortunately, if only power resistors were used, the MPPT algorithm in the microinverter would measure higher power at ever-increasing current.   Is 10 Amps enough? 10 Amps X 40V is 400W, great.  Is 11 Amps enough? 11 Amps X 39V is 430W, better... and it keeps doing this, until it exceeds its own power rating (and/or catches fire).  Microinverters are designed for solar panels only, and the "knee" of the curve keeps them safe.  I don't believe that the microinverter will self-limit (but maybe it can).
  • To keep the microinverter from blowing itself up, I've introduced a FET shorting across the 4 Ohm resistor.  By doing this, the voltage drop can be controlled and simulated, like a PV panel was there.
What does the FET do?
  • When the FET is on, the current is basically shorted to ground, which is like the typical use of most N-channel MOSFET controls for motors and heaters.  The microinverter will see lower resistance and current can increase.  Left to its own, its MPPT will seek more current to increase power output.  This simulates being on the right side of the knee of the PV Panel I-V curve, increasing current and voltage will drop slightly.
  • When the FET is off, the current admitted by the microinverter is subject to a lot of voltage drop, so much that there is a strong voltage drop.   Now the MPPT algorithm will measure lower voltage and determine that the input power is dropping, thus the current is too high.  This simulates being to the left the knee of the PV Panel I-V curve, where voltage has dropped due to more current.

This the Arduino needs to control the gate of the FET seeking a balance between current and voltage.  This will need tuning so that the characteristics of the microinverter don't set up a "fight" between the microinverter's MPPT algorithm and the Aurduino program I write to manage the same thing.
67
Wind Power Machines / Re: Interfacing wind turbines to the grid
Last post by SparWeb -
At this point, the ideas I'm sharing are partly based on a device I developed with Glen Hurd (aka GHURD) from the old Fieldlines board.  He deserves credit for doing a lot of development work to make a similar device work, which I built and used for years.  It was called an "opportunity diversion load timer", which "sniffed" when the charge controller was running the diversion load, and switched on some kind of DC or AC load that could be used instead.  While the AC or DC load was running, the batteries were being drained thus the need for a diversion load by the charge controller was relieved.  So instead of running a heater in my garage, a heater kept water for our horses thawed in the winter.  This saved me a lot of money and this device paid for itself quickly.

I just wanted to pause and give a shout out to GHURD, wherever you are.  Your ideas live on and I'm still using them.
68
Wind Power Machines / Re: Interfacing wind turbines to the grid
Last post by SparWeb -
I spent more time this weekend working on the design.  I've attached a circuit below.

A few things to know before going in (not really meant for you, BRCM, but others reading this later):
PV panels have a typical Current-V-Voltage curve.  While each PV panel has a slightly different curve, in general they all look the same: flat top, curve, steep slope down.  Where it curves down, I refer to it as the "knee" if the curve.  You've probably heard the term before, but if not, think about how your knee looks... take a look at the example I found.
MicroInverters are designed to convert PV panel DC electricity into AC for the grid, and connect automatically.  This is super-convenient and simple to install, but let's note that they won't convert DC from just any source.  Most if not all of them also are programmed with a Maximum Power-Point Tracking algorithm.  They will adjust the current flowing at any given moment to find the peak power.  If a microinverter was connected directly to a battery, it would not detect a knee of a curve, because batteries do not have a power curve like a solar panel does, and a microinverter would then either run the battery flat or set itself on fire.  Place bets on which fails first.
Wind turbines are built either for connecting to the grid or connecting to batteries.  Generally the battery-connected wind turbines are for off-grid purposes, and require a battery to work.
Batteries are a great part of any RE system, but very rarely can they used as an energy storage for exporting energy to the grid.  Some inverters can do this, but I have found that the conditions needed to allow an advanced hybrid inverter to export energy stored in a battery would make it impossible for the battery to be charged by anything other than that advanced hybrid inverter. Usually people who want their batteries to backup their AC will either use an off-grid inverter or a hybrid inverter but allow no other connections to charge the batteries otherwise.

At this point, it seems like a battery-charging wind turbine is therefore not going to be grid connected.  End of story?

...but what if...

I'm working on a device that can unite the battery to the grid, thus exporting excess energy that would otherwise be spent as heat in the diversion resistors.  It's done via a microinverter, but also controlled to trick the microinverter into thinking it's connected to DC solar panels.

In the circuit diagram, the charge controller, diversion load resistors, micro-inverter, and relay are all common off-the-shelf parts with no modifications.

The Arduino/Feather has several functions.  If you've ever seen an Arduino or a similar micro-board, you have seen you can stack boards together on the same microcontroller board.  For this I'll be putting a "relay board" on top of a "prototyping board" on top of a Feather/Arduino board in a 3-layer stack.  I'm not sure but I may need to do something strange to get the FET's to fit on the prototyping board before stacking the relay board on it...  I haven't built these parts yet so I don't have pictures yet.
69
Wind Power Machines / Re: Interfacing wind turbines to the grid
Last post by bigrockcandymountain -
So what is the best plan you have so far? What exactly would the microcontroller do? You said the load terminals on the solark can take ac or dc is that correct? 

I'm excited for you, and also interested in using an ev as a dumpload here, so some stuff might be applicable to that. 
70
General Discussion / Re: Welcome to FieldlinesForum! Your new Community.
Last post by eColumbus -
Hi everyone,

Thank you all for the kind words. It is good to see a lot of familiars faces here.

Bruce, it is fine to tell the whole world about the forum, the more people that know the better.

Once I catch up on a few things I’ll have time to post a few things, and maybe a small project to start with.

Today I had to do electrical work for my wife’s new coffee shop that she got for Christmas. That was one of the worse wiring jobs I’ve ever done. The lamps for the ceiling were tiny LEDs that came with 30 Ga. wires. I hope that she doesn’t get another house next Christmas.

Hey Spar, I see that you were itching to start posting, keep it up Newbie, you need to earn some stars.  ;) 

Ed