Vendor Claims

The shakeout of all things “smartgrid” appears to be proceeding in a healthy fashion. Early claims about the marvels that applying 21st century technology to 19th century wires have calmed down. Clear heads have made sense of the important data security issues and electric utilities remain protective of their networks with increased sophistication. The market has sorted through the SmartGrid vendors and the ones that remain do so because their products have potential to deliver real value.

Now is the time to be sure about the details. Virtually all the SmartGrid products aimed at the electric utilities measure electrical parameters somewhere in the grid, process the data and send it along to another system to be acted upon or stored. Common sense has it that all this new data is only as good as the metrology creating it but entrepreneurial SmartGrid companies often don’t give this basic truth the attention it deserves.

One of the best examples of this occurs in products designed to give electric utilities a deeper view into their medium voltage networks. These devices may not have access to the low voltage side of the network so preserving ability for ubiquitous deployment means they must be powered creatively via inductive energy harvesting, solar cells, batteries, RFID methods, etc. If operating power is in short supply these devices revert to low power modes with limited functionality or “sleeping” most of the time waiting for notable power system events. All is fine until the potential utility customer asks the vendor to add a staple “bread and butter” measurement like 10-minute average RMS current or voltage to the deliverables list and the marketing/sales guy eagerly agrees in order to close the deal.

Averaging anything over time implies taking an equally-spaced time series of measurements over the interval. Computing any RMS value itself implies doing yet another integration over time, generally with smaller intervals. If the device cannot be ON for the entire duration to do this properly, some compromise is required and there have been some remarkably bad implementation choices. For example, one vendor’s clever instrument would actually go to sleep for 9 of the 10 minutes, take 10 measurements in the last minute, average those and present the result as the “10 minute average.” The problem is that the first 9 minutes are vastly undersampled and the reported result contains no information about what actually went on during that time. The last 1 minute is highly oversampled for normal grid variations and the precious power invested in doing that metrology is largely wasted. What’s worse is that the utility didn’t ask nor did the vendor tell them exactly what the “10 minute RMS” number meant. Things got messy later when the vendors’ gear did not agree with other conventional instruments the utility had come to trust over the years.

If you need to get the right answer, details matter. DJA Engineering can help protect your SmartGrid project from unrealistic expectations, misunderstandings and maybe even legal bills later on.

Areas of Expertise

DJA provides a broad range of engineering services from technical consulting to full design/testing of AC power measurement systems operating at voltages from 120V to 35KV. We help get your power metrology job done cost-effectively with a wealth of knowledge in the following areas:
We are experts using modern digital sampling techniques with both time and frequency domain data analysis methods for the full range of home/commercial/professional applications. [learn more]
Current/voltage transducers are a necessary evil and we understand how to identify the best ones for every job. We also have particular expertise in Rogowski coil current sensors. [learn more]
Extracting what one needs to understand from standards is rarely easy and some important ones are downright daunting. We have a broad understanding of the applicable standards and can help navigate the best path through the maze. [learn more]
Safety must be designed into every power metrology product and assurance is a big deal, especially for high voltage electric utility equipment. We are also experts at making best use of expensive external labs. [learn more]
Neutral, third party evaluation of the methods used and data being delivered by newer SmartGrid instruments can streamline procurements, expedite trials and maybe even avoid legal bills. [learn more]
We have deep experience with both narrow and broad band PLC technology can make it work for you when that makes sense or make sure you avoid it when it doesn’t. [learn more]
We have a collection of reference instruments and intimate knowledge of the tricks of the trade. We can work with you in depth or provide just the specific answers you need for your project. [learn more]