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Analog Devices unveils new generation of energy metering ics to deliver highest accuracy for billing and power quality monitoring applications

This month a quartet of energy metering ICs have been unveiled by Analog Devices, Inc., to improve the accuracy and performance of commercial, industrial, and residential smart meters.

ADI's new ADE7878, ADE7868, ADE7858, and ADE7854 energy metering ICs have been designed to enable smart electricity meters to deliver improved customer billing accuracy, advanced power quality monitoring, and reduced operating costs for utility companies.

ADI claims to have supplied more than 250 million ICs for use in energy meters worldwide. In this news analysis article Analog Design Line Europe's editor, Paul Buckley finds out more about the significance of the new generation of energy metering ICs in this expanding market by interviewing Mack Lund who is Manager of Analog Devices' Energy Metering group.

Analog Design Line Europe: Where does this energy metering ICs family announcement fit in the bigger picture of global energy efficiency?

Lund: We are seeing a lot of excitement about the so-called Smart Grid and the Smart Grid roll-out that is happening worldwide. There are a lot of promises around the Smart Grid technology. We hear promises of increased robustness and reliability of electricity delivery. We see the opportunity to provide for easier connection of new renewable energy sources. We see the opportunity overall to have increased efficiency.

However, we also do see a number of challenges with the Smart Grid. Just a few examples include: What do you measure? How do you measure? How do you communicate the data that you measure that is needed to reliably roll out the Smart Grid?

Also how do you manage inherent uncertain availabilities, for example, renewable energy sources off the Grid? Previously the Grid was a little more uncertain and had only a few parameters for measurement we are now seeing much greater complexity.

As a company we have seen this kind of growing complexity and sophistication opportunity within this market and we have acted to organize ourselves to address this new segment. Our new dedicated energy group will provide a better focus on these new opportunities and provide a better linkage between customer needs and our technology group.

A couple of examples of these kind of opportunities include the fact that today more and more governments are mandating Smart Grid technologies or other energy infrastructure investments. Of course, China is probably the largest of those and has announced $596 billion in energy infrastructure investments that include the deployment of more than 150 billion smart meters. There are also a number of large scale deployments that are already happening or have already happened in North America and throughout the rest of the world.

Eighteen million homes, which is 13 percent of all U.S. households, will get smart meters within three years as part of U.S. government grants to upgrade the country's electric grid. In Europe, Italy and Sweden have already completed Advanced Metering Infrastructure (AMI) deployments that converted all meters to smart meters. France, Spain, Germany, and the United Kingdom are expected to complete AMI roll-out within the next 10 years.

We see energy metering as being at the heart of all this Smart Grid investment.

Analog Design Line Europe: Who are the main customer groups you are addressing with the energy metering ICs?

Lund: When we set out to define and develop our next generation of analog front ends with metrology engines for specifically three-phase industrial and commercial applications we looked at the three major user groups.

One of those users is the Utilities themselves which use the chips to accurately measure and bill for electricity usage.

The second group are industrial users that use the chips for understanding power quality in order to provide greater efficiency.

Then the third group is the designers, who are the ones we directly interact with.

In each of these cases the groups of users have a number of needs that in the past have not been met by the previous generation of meters and this is providing us with an opportunity.

Utilities

For the utilities, first and foremost the electricity meter, by extension the metrology chip, is really the equivalent of a cash register. It must be extremely accurate and reliable. Increasingly utilities are also looking at the meter not just for billing but there is the network assessment that enables monitoring of the overall power quality. These remote monitoring and conditional control capabilities that are enabled by the Smart Grid can result in significant operating cost reductions. One example is that Italy has already rolled out a 35 million meter network. They have announced that by managing their network more remotely and running their power plant more efficiently based on the information from the smart meters they are saving millions of euros. The utilities are now seeing real benefits form the move towards Smart Grid technology.

There are many utilities, particularly in developing countries, where a lot of the power is not metered and there is tampering. People are actually stealing power and utility companies are interested in using Smart Grid technology, metering and better metrology solutions to be able to more accurately measure power that would have been lost previously. There is a demand to be more accurate about the power that is lost.

Tamper detection has become quite a large issue in some of countries such as India, China and many other developing countries. In some countries as much as 30 percent of energy can go unmetered because of tampering. In some countries it is very, very widespread. In the US and many parts of Europe it is not as yet a widespread issue so meter makers in these regions are tend to be less concerned about providing these anti-tamper capabilities.

Industrial users

Industrial users are facing a number of challenges. They are not really using the meters for billing purposes, however, energy is a large part of their expense. They have a need for accurate measurement which enables them to be more efficient with their energy.

It is not just energy consumption but for them it is an issue of power quality. One example is that many industrial companies have to contractually commit to provide a certain level of power factor for the energy they consume. So they need to accurately monitor what that power factor is. Not only is there compliance for their plant but throughout their plant they need to know which machinery is contributing to the power factor. Other things might include monitoring power frequency harmonics to make sure that damaged equipment is not left on the power line unmanaged. They need to discover whether equipment is being inefficient.

Meter designers

The meter's designers face the need to design a more accurate meter or more feature rich meter. Meters used to be on a very slow time-to-market timescale. Recently they are now faced with a much faster update and time-to-market requirement. They require a part they can integrate more quickly and they need a part where they can have more of a design margin they can work with. They can bring a meter together and tweak every last bit of it to get the kind of accuracy they need. They want to minimize the overall total solution cost. They want interface flexibility and they want excellent design support and to work with suppliers that can deliver high quality products in high volumes and to schedules that they need.

Analog Design Line Europe: What competitive differentiation is now possible with the new technology?

Lund: In the past meters were fairly simple devices and often basically an electromechanical device and the only function it really provided was measurement of real power. You know the kind of thing where you just spin a little disk and the meter reader would come around and read how much power had been consumed. So there was very little scope for product differentiation with a specification then. What we are seeing now is almost an explosion of different needs that are driving the market. On the metrology or measurement side people are looking to measure much more than just real power. We can measure reactive energy. We can measure active energy. We can look at all the quality measurements such as line voltage, sag, the rise above a certain level. We can use those quantities to calculate the power factor. We can look at harmonic content. Then there are anti-tamper features. These are all a variety of features that can now be added to a meter to differentiate it from your competition.

There are also a number of fundamental performance parameters that would differentiate a meter. These would include base accuracy. A meter that is capable of measuring a much, much smaller current would be very accurate. And then there is dynamic range, where you can not only measure a small current but also a very large current.

Our ADE7878 poly-phase multifunction energy metering IC is the flagship component.

One of the key points with the ADE7878 is that for the first time an energy metering IC achieves better than 0.2 percent accuracy not only on the active power or real power but also on the reactive power. With the increased demand to understand what is going on with various loads on the power grid this more accurate reactive measurement really provides a benefit to various users. It enables a more accurate power factor measurement that helps to implement greater efficiency.

Without a doubt accuracy has to be a key feature. The ADE7878 offers the highest overall poly-phase accuracy and exceeds the Class 0.2 spec. We can achieve 0.2 percent accuracy over the dynamic range of up to 3000 to 1.

Perhaps the best way to describe the dynamic range in relation to the accuracy is to give an example. A typical US or European home might have an electricity service that is 20 V it may have 200 A current. The ADE7878 could measure the energy of a load with a range from 200 A all the way down to 0.2 A with an error of less than 0.1 percent. If we wanted to go down and measure much lower currents we could go as far down as milliamps.

The key thing about this accuracy is that it applies not only to measuring the active energy but also to the reactive energy and that's really a first.

Harmonic measurement capabilities represent the second major breakthrough with the ADE7878. The device has the ability to simultaneously measure energy on a fundamental basis and also measure the energy in the harmonics that are added after that. Specifically these would be undesirable or noise components. For both the fundamental measurement as well as the harmonic measurement the ADE7878 measures total energy, active and reactive energy for the fundamental and for the total wave. This is the feature that really enables much better power quality measurement, particularly for industrial applications but also for utility customers.

This is important because we have many loads on a network now. These include advanced motor control, switching power supplies or any other non-linear power loads. All these are in a sense polluting the power grid with harmonic content. This will lead to lower energy efficiency and could potentially damage sensitive devices like those used in hospital equipment. To make certain this kind of equipment will operate perfectly and safely it is important for us to be able to make design changes and this means we need to know the harmonic content and the energy content. The ADE7878 provides features to do that and for the designers that want to go further down into the detail and analyze various specific components of the power waveform. The raw waveform or raw sample can be studied by the designers with a variety of different interfaces. They can implement their own advanced analysis.

A third key differentiator in the ADE7878 is the anti-tamper function that we have built into this product to allow designers to very quickly and easily implement an anti-tamper feature to their meter design.

The tamper detection capability not only offers the ability to detect tampered conditions but also has the ability to continue to keep operating under certain tampered conditions.

A key feature in relation to this is that we include a seventh ADC channel. So we have six ADC channels to measure the three-phase voltages and the seventh ADC channel for measuring current from the controller. This can used to compare the measurements to detect any tampering.

In the case of a mis-match the metering IC can be used to monitor the mis-match and record the potential tamper event. Not only that it can be configured to meter energy on a certain current values and will continue to properly record what will be the most likely accurate billing conditions.

Analog Design Line Europe: What is the Importance of the active and reactive energy concepts?

Lund: The ability to measure active and reactive energy enables users to monitor the behaviour of loads they are metering. One example is an industrial facility may be running a very large three-phase motor that runs. They may also have certain equipment that will compensate for that reactive energy that that large motor requires so.

The active energy goes to providing real work in the motor while the reactive energy is energy that has to be supplied but doesn't really go to providing real work. Customers are interested in compensating for that reactive energy

Where he metering chip really helps is that enables the industrial user to monitor the amount of the reactive power and real power that are going into the machinery. They want to minimize reactive power they are using by perhaps using compensation components. In order to do that they need to have an accurate measurement of how much reactive power is being used. By knowing the accurate measurement they can then take certain actions such as buying compensation equipment or whether they can understand how close they are to the limits. It enables them to have good measurement and insight that allows them to make good decisions about corrective action.

Analog Design Line Europe: Are samples available and when will the products be released?

Lund: Samples are available now. Product is scheduled for February 2010.

The ADE7878 poly-phase multifunction energy metering IC is designed to support today's intelligent meter and Smart Grid applications, including:

Per-Phase Measurements:

  • Active, reactive and apparent energy
  • Total and fundamental only energy
  • RMS current and RMS voltage

  • Digital calibration

Power Quality Features:

  • Line voltage period measurement
  • Angles between phase voltages and currents
  • Phase sequence
  • Sag and peak detect
  • Over current

  • Over voltage

Mack Lund is Manager of Analog Devices' Energy Metering group. Lund joined Analog Devices in 2003 and now manages its metering components business. Before his current role, he held various marketing and product management positions at Analog. Prior to joining Analog Devices, Lund was a senior design engineer at the Westinghouse Science and Technology Center and Siemens, where he worked on research and development of high power electronic systems for utility applications. Lund holds a Bachelors degree in Electrical Engineering from Brigham Young University, a Masters degree in Electric Power Engineering from Rensselaer Polytechnic Institute, and MBA and Masters in Electrical Engineering degrees from the Massachusetts Institute of Technology.

Related links and articles:

Energy metering IC family claims 0.1 percent accuracy for both active and reactive measurements

ADE7878

ADE7868

ADE7858

ADE7854

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