blog

What is a smart meter?

This blog entry is part of a series of posts introducing the topic of smart meter disaggregation.

Your existing electricity meter probably looks something like this:

Attribution: Kristoferb at en.wikipedia

(image taken by Kristoferb at en.wikipedia)

By 2019, the UK government have mandated every electricity meter in homes and businesses will be replaced by a "smart meter" (that's a grand total of 53 million meters).  A smart meter is simply a digital meter with some basic communications functions.  It will be paid for and installed by the utility company.  It will talk to the utility company over a GPRS data connection; and it will also be able to talk to the "home area network" to provide data to in-house energy displays.

The draft spec for smart meters in the UK was published by the Smart Metering Design Group in August 2011.  The specification states that the meter must be able to supply meter readings to the home area network at a rate of one reading every five seconds.  The meter will measure voltage, real power and reactive power (in both directions).  Some utility companies have already started to install smart meters; British Gas plan to have 2 million smart meters installed by the end of 2012 (Centrica, 2010). 

If you can't wait for a smart meter to be installed then you could buy and install a "home energy monitor". These are available for around £40; although some utility companies give them away for free.  Home energy monitors are user-installable.  I used a Current Cost home energy monitor for my MSc project on disaggregation.  It recorded a sample of apparent power once every six seconds.

This is a reading produced by my Current Cost home energy monitor:

meterPlotmeterPlot

The value of sample at time t is the sum of the power being consumed by every appliance active at time t​.

Existing central heating control systems

A little while ago I wrote some notes describing my "ideal" central heating control system, which I was planning to build myself.  Time is short so it looks like this system won't be built for a while so I need something which I can buy off-the-shelf which will satisfy as many of my requirements as possible and also leave the door open to DIY tinkering in the future.  This blog post is a collection of notes about off-the-shelf central heating control systems.

Insulating our Victorian living room part 2

We live in an end-of-terrace Victorian house, built around 1905.  I've spent the last few years insulating our living room.  This blog post is the second in a two-part story.  By the end of the first part of the story, our living room looked like this:

_DSC0240_DSC0240

I'm pleased to say that our living room now looks like this:

_DSC0038-1_DSC0038-1

One big design change since my last blog is that we decided to install wet underfloor heating ourselves.

So, let's start the story...

LSE Podcast: State of the World Economy in 2012

The London School of Economics produce an excellent series of podcasts.  Last night I listened to "State of the World Economy in 2012".  Packed with lots of juicy economics facts and analysis.  One point which stuck in my mind was the suggestion that, in previous global economic slumps, a natural ballancing force has been the reduction of commodity prices.  Yet, this time around, commodity prices are not reducing; far from it: most commodity prices are at or near their peak values despite very low growth in many developed countries.

Rotate iPhone video 90 degrees on Ubuntu

A very quick note about rotating .MOV videos shot on an iPhone 90 degrees clockwise on Ubuntu.  The first tool I tried was ffmpeg but it turns out that the Ubuntu version of ffmpeg isn't compiled with the -vf command-line option enabled. You could re-compile ffmpeg from source but it's easier to use mencoder:

sudo apt-get install mencoder
mencoder -vf rotate -o Input.MOV -oac copy -ovc copy Output.MOV

(I was using -oac lavc -ovc lavc but any anonymous commenter suggested the much better idea of using copy)

Free Stanford course on Probabilistic Graphical Models

One of the main research directions for my PhD is likely to be experimenting with bispoke probabilistic graphical models for representing multi-state appliances like washing machines.  As such, I need to learn about existing probabilistic graphical models.  For the past few days I've been reading a textbook called "Probabilistic Graphical Models" by Koller and Friedman.  So far I've really enjoyed the book.

Over lunch today, a friend of mine told me that Stanford are running a free on-line course on Probabilistic Graphical Models, presented by Koller. I've signed up - it looks like a great course; it starts in Feb. Stanford are also running a course on Information Theory, which I've also signed up for.

My copy of David MacKay's "Information Theory, Inference and Learning Algorithms" arrived

My copy of David MacKay's book "Information Theory, Inference and Learning Algorithms" arrived yesterday and I started reading it last night. It looks absolutely fascinating.

I first came across Professor MacKay when I read his other book, "Sustainable Energy Without the Hot Air" and  I was struck by how lucid, readable and entertaining it is. There is every reason to expect that his information theory book will be at least as readable.

Why get a book on "Information Theory, Inference and Learning Algorithms"? The main reason is because it should be very useful for my PhD in smart meter disaggregation. One of the god-fathers of disaggregation, George Hart, wrote the following in Hart 1992:

It is insightful to consider the [disaggregation problem] in the context of a communication model. Appliances can be thought of as “transmitters”, inadvertently broadcasting information as a by-product of their operation. The communication “channel” here is the house wiring. Any of the many signatures... may be the “codes” used in this communication scheme. Our task is to design a “receiver” for these codes which can decode them in terms of appliance state-change “messages”.

In other words, the disaggregation problem can be considered in an information-theoretic framework. This conceptual step allows us to take advantage of the tools developed in communication technology (i.e. coding theory).

Also, for a while now I've thought of information theory as one of those "sexy but mysterious" things which I'd love to learn more about. I read "Decoding Reality: The Universe as Quantum Information" a couple of years ago and found it fascinating (although I only understood about half the content of the book).

So, hopefully MacKay's information theory book will be a great self-study book.

My MSc project on disaggregation is on the Imperial website

During the academic year 2010-2011, I did a computer science MSc at Imperial (which I thoroughly enjoyed). During the last 3 months of the course, each student does an "individual project". Mine was on "Disaggregating Smart Meter Readings using Device Signatures" and the PDF is now available on the Imperial website (note that my birth name is "Daniel" although I've had the nickname "Jack" since I was 11!)

This MSc project formed the basis for my PhD (I'm doing my PhD with the same excellent supervisor with whome I did my MSc project). 4 months into my PhD, I now recognise that my MSc project was pretty naive but it was lots of fun!

E-readers for academic papers & converting LaTeX to EPUB

I currently read academic papers by downloading the PDF and printing; and the tiny collection of LaTeX documents I've authored are output as PDFs. It feels like I should embrace e-readers for academic reading and writing. I have a Kindle Keyboard which does handle PDFs but reading PDFs is not especially pleasant on the Kindle because of its small screen, relatively sluggish refresh rate and clunky note-taking feature.

Reference library available online

I've been using Zotero as my reference manager for my MSc project and my PhD.  It's free.  It's open source.  It's awesome. One of the really nice things about Zotero is that you can easily publish your library.  So that's what I've done. There are references on climate science, smart meter non-intrusive load monitoring (NILM), graphical models and a few other subjects.

 

Pages

Subscribe to RSS - blogs