DOE Smart Grid Demonstrations
December 2, 2009
Check this post for some detail on energy storage demonstrations that were recently funded: link
Category » Smart Grid
Write-up on ioBridge Projects
I just noticed a write-up on the Remote HVAC Control and Home Power Monitor on ioBridge: link. Oh, the power of recursion; again.
Remotely Enable/Disable A Thermostat
July 20, 2009
A simple way to handle the issue of remotely enabling and disabling your thermostat can be valuable for turning the system on when you return from vacation, or turning it off when you realize you will not be home when you originally planned. The objective is to remotely control whether or not the thermostat is connected to the furnace/AC. I used the ioBridge and a DPDT Relay Board to interrupt the 24VAC that is fed to the thermostat.
Note that most of the newer HVAC systems ramp the system up and down to increase component life. I decided to use this technique on my system because it is 30 years old, and therefore not as finicky.
First I had to learn how my home thermostat is wired. Picture is below.
- This is the wiring beneath my thermostat
This is a typical 4-wire system (1 heat & 1 cool) operating at 24VAC. The furnace has a transformer that supplies the 24V which is wired to the RH (heat) and RC (cool) terminals on the above block. The thermostat decides when to activate the fan, AC compressor, or furnace gas valve by sending the 24V to the G, W, or Y terminals respectively.
All I did was just send the 24VAC power from the transformer through the relay board. Ignore the other little boards connected to the ioBridge; they are for other projects.
- The 24VAC control wire passing through the relay board connected to the ioBridge
I decided to use the Normally Open connection on the relay board. So, in the case power is lost to the relay, it will revert to an open connection, and the thermostat will be disabled. I thought this was important because if we are traveling, I want the HVAC system to turn off when something goes wrong. Of course this means the system will turn off if we are home when something goes wrong as well.
Now, when we all go on vacation, all we need to do is decide if we might need heating or cooling when we return, and we will set the thermostat in that mode before leaving. If we had a newer auto changeover thermostat, all we would need to do is turn it on auto. Then we disable the thermostat using the ioBridge control, and leave. When we are returning, we just enable the thermostat via ioBridge (like via an iPhone on the way home from the airport.) The house will be comfortable when we get home.
Likewise, if we are out for the day and decide to not come home that night, we simply disable the thermostat via ioBridge until just before we return.
Home Power Monitor
July 10, 2009
I completed the installation of a power monitor for my home. The web page is here. The chart comes from Google Charts; you need to wait for the chart to build over time.
It is intended primarily for relative power monitoring, not ultimate accuracy, and the energy can only be logged for short periods. It does not include power to my air conditioner (which we do not use much anyway) because that load is connected directly to the main panel, which is not adjacent to the Ethernet port I have in my garage.
There are also two temperatures reported on the web page, as described.
Credit given to Jason Winter who created this solution and published it here and here.
My implementation is slightly different from Jason’s. I utilized a different op amp (AD627), a different offset (0.5 VDC), and keept mine on a breadboard for future upgradability. I used a box with an added terminal block to convert from the CT banana plugs to lead wire for connecting to the conditioning circuit. Of course I lifted his HTML code, but modified it for my ioBridge widgets, as well as for my power factor assumption and calibration constants.
A key learning is how difficult it was to install the current transformers. There was barley enough room for them in the sub-panel. I used the Steren PUN-285 as suggested by Jason. But these CTs are really for temporary installation, and therefore are not optimized for minimal space. It was a chore to get the panel cover back on in my particular case.
Sub-panel with power monitor above
Detail of current transformers on two legs.
Detail of ioBridge (left), breadboard with two conditioning circuits, and terminal conversion box.
Follow the (Recovery) Money
April 9, 2009
In the case you are interested to know detail about what initiatives the American Recovery and Reinvestment Act (ARRA) stimulus package (recovery bill) may fund in California related to the Smart Grid, there is public information available on this topic. The reason this is important for cleantech/greentech is that the ARRA appropriated $4.5 billion for the Smart Grid country wide which will reduce energy consumption and enable the transition to renewables. The reason it is important to Californians is that we need to compete with other states to get our piece of the pie, not only to shift our energy paradigm, but also for jobs.
Relevant information may be found here. There are links to presentations by the three Investor Owned Utilities (IOUs) given at a workshop on March 27. I attended the workshop and am glad to see that the information has now been posted. The IOUs provide information about the projects that they want funded, often listing the dollar amount, the expected jobs created, and even the vendors involved. Projects are in the following categories: Smart Grid testing, Smart Grid demonstrations, synchrophasors, grid energy storage, auto-derivative battery storage, security, microgrid, smart-thermostats, PHEV truck fleet, demand response, and EV studies.