Smart Meters - An introduction

Smart Meters - An introduction

• INTRODUCTION
  Like any commodity, energy, gas, water and sewage disposal must be measured to be sold. Over time a number of technologies have evolved to accomplish this goal. Naturally as long as there has been a way to meter a service, there have been people trying to figure out how to get around the metering systems and get those services for free. This paper will examine some of the new metering technologies and compare them to the older traditional methods in the light of a secure implementation.
  
  
  TRADITIONAL METERING (Electro Mechanical)
  The way services and utilities have traditionally been monitored has been with a mechanical system. Gas or water runs past some sort of vane which spins, driving gears and turning dials. Similarly a mechanical electric meter uses induction loops to spin an aluminum disk which then turns gears that spin dials. Of course this data needs to be collected to be billed. With this type of metering, a utility will typically get an actual read through a meter reader and use sophisticated statistical modeling to estimate the rest of the time. How often the actual read occurs is really a function of state regulation and utility policy. Now an interesting thing that you can do (among many) is that if you understand the cycle that your utility uses, you can invert the meter. That’s right, pull it out of the socket, turn it over, put it back in and you still get electricity, but the meter runs BACKWARDS! Cool, free electricity as long as you don’t let the meter reader see the meter installed upside down. Some meters had mechanisms to prevent them from running backwards, but not all. A way the utilities have come up with to combat this and other methods of fraud goes back to the sophisticated statistical modeling. If the system sees a significant change in your usage pattern, you get flagged for a live read.
  
  
  AUTOMATIC METER READING (AMR)
  Automated Meter Reading was introduced to accomplish two primary goals; improve the accuracy of metering by getting more live reads, and reduce the work force required to gather meter data. AMR is set up to send the data back to the billing system via some communication method, be it fixed service radio, data over power line, Meter reader with a handheld device, or by a truck driving around and gathering the data over a low power radio link to the meter. AMR introduced another interesting feature: the ability to detect if someone had tampered with the meter. As the technology has advanced, and traditional mechanical meters are replaced, AMR systems have become increasingly prevalent. The major downside to an AMR system is that it is mostly a one way communication system. The meters “bubble up” the data on a periodic basis to the utility. Newer Advanced AMR systems have integrated some limited two way functionality adding features like reading meter data on demand and remote disconnect switches. “Demand Reset” is also a function sometimes provided in two-way AMR.  When you track a customer’s peak demand, the meter records the maximum peak instantaneous usage over a period.  At the end of that period, you need to reset the demand back to zero so you can record during the next period.  In earlier days, there was a locked button or lever the meter reader would press (they had the key) when they did the readings.  More modern devices can do it based on a clock.  In two-way AMR you can send a demand reset command after you’ve successfully retrieved the demand value.  This inevitable march of progress has led us to the latest in service metering technology, AMI.
  
  
  ADVANCED METER INFRASTRUCTURE (AMI)
  Advanced Meter Infrastructure is where it gets cool (and spooky to some). AMI is the natural evolution of AMR technology. A full two way communication system that allows on demand reading, Time of Use (TOU) billing, remote disconnect operation, load limiting, demand response, and more. Where things get really interesting is when a Home Area Network (HAN)is integrated into the meter. Now the meter can talk to properly equipped furnaces, air conditioners, water heaters, micro generation systems, thermostats and In Home Display (IHD) devices that tell you just how much running the dishwasher will cost you to run at 3 in the afternoon vs. 3 in the morning. Past that it enables portable billing and usage of Personal Electric Vehicles (PEV) which can also be leveraged as local storage devices to help manage load spikes on the distribution system. Another interesting feature is the ability to subscribe to a service from the utility that allows them to reduce your power consumption by managing large appliances in return for a lower billing rate. 
  
  
  Notice I said SUBSCRIBE. You have to sign up for it. This is important because for all the really interesting things AMI can do, it has also stirred up some serious political debate. While the technical concerns around security are addressed further on, let us examine the paranoia that AMI has raised. The first fear is that The Government (you know who I mean, the socialist/fascist (sic) fat cats in and around DC) is going to take control of your appliances and dictate when you can use them, and how much. This is followed rapidly by the fear that The Government will collect your usage information and somehow use it against you. None of this is helped by political pundits and demagogues who have decided to whip the masses into a frenzy using this as one of the egg beaters. Politics aside, there ARE some genuine security concerns to look at, and that is one of the things we will look at starting with the next installment, “The Risks”
  
  
  There are some intermediate steps in the evolution from electro mechanical metering to AMI, but they are outside the scope of this discussion. If you would like more information about the details, Wikipedia has some good articles.