Getting basic utility meter designs ready for the Smart Grid

Companies around the world are sensing huge business opportunities in power grid design because of two things. First, utilities in US and Europe are embarking upon replacing over 45% of the existing utility meters by 2015. Second, there are huge requirements in terms of units being created by the swelling consumer and industrial base in the developing nations like China, India, Brazil, etc.

According to one projection, there is a requirement of $19.5 billion worth of utility meter and related communications between 2010 and 2015 with an estimated shipment of over 200 million smart-meters [1]. The graph in Figure 1, below from a different source, gives almost the same projections.

The purpose of this article is to serve as a guide to determining the system-on-chip architecture for a basic utility meter that will 1) serve the basic purposes and applications of the present day market: measurement of consumption, tamper protection, time keeping, display and transmission of the meter-reading, and 2) can be used as the baseline upon which future designs will be derived.

The features and modules discussed here should serve only as a starting point - not as the end of the road - for metering SoCs and should signal what lies ahead. Peripherals like USB, Ethernet, etc are jostling their way into the next generation of the metering SoCs, better known as Smart Meters.

Nowadays, a meter does not do just the measurement, protection, etc but can do a lot more tasks e.g they can interact with the consumer via a smart touch screen display and signal him/her the present consumption. They can also monitor each and every appliances of the home/office and tell which one is consuming how much of energy.

Using Ethernet, the consumer can operate the appliances of one place while sitting at any other place on this earth, like switching on the AC right from the office so that the user gets cozy colder home when he/she reaches home.

Also, AMR (Automatic Meter Reading) is going through a long revolutionary way. Now the options could be to install pre-paid meters, take the reading using IR/ZigBee receivers or using Ethernet or GPRS. Smart Grid is also going to revolutionize the world of metering in terms of the transmission, fault location, etc.

In a very real sense, today's basic metering designs are going to be the beginning of a new world of applications in Smarter Metering.

Figure 1. Meter Demand Projection between 2008-2012.(Source ABS Energy Research[2])

All the above mentioned functions of a utility meter can be achieved using the building blocks as shown below in Figure 2 below. As shown, it consists of the following elements:

1) Analog Front End to measure the Current, Voltage (for energy meter) or Heat (for heat meter) or maybe the output of the Analog Sensors (flow, gas meter),

2) A Flow/Gas measurement unit which works using the output from the digital/analog sensors. (flow, gas meters),

3) Tamper protection and detection logic,

4) RTC (real time clock) for time keeping purposes,

5) Communication peripherals to communicate with the external world like with ZigBee transceivers, RF transceivers or another SoCs,

6) Display drivers to display data like meter reading, date-day-time, etc.

7) Core to process the data to give the consumption and to do other tasks,

8). Memory to save the data like meter reading and time of the tamper event, etc.

Now, let us explore each block one by one.

Figure 2. Building Blocks of the Basic Utility Meter.