Harmonics open up itemised billing in smart meters

October 05, 2017 // By Julien Happich
UK R&D services company 42 Technology has developed and patented what it calls Triple Ohm, a sensing circuit based on shunt resistors which it says can deliver very accurate power measurements without a bulky copper coil.

The company has been delivering solutions to big metering companies and providing wireless monitoring of 3-phase meters to prevent tampering and power theft in developing countries.  Although the technology was initially developed in the nineties for 3-phase meters, the engineers at 42 Technology realized it could also be used to measure the changes in the high frequency current or voltage harmonics within a single-phase power line.

Monitoring these changes, the company observed that each specific class of appliances (washing machines, kettles, vacuum cleaners etc…) had a characteristic harmonics trace, which could be identified by a specifically trained data analysis algorithm so as to be dissociated from other profiles.

Sampling current and voltage harmonics at 48kHz, a smart meter integrating Triple Ohm can break down the power consumption per device, enabling utilities providers to deliver itemised bills to their customers. The data could also be displayed in real time via a smartphone app or a low cost home energy monitor. Sensing is so accurate, claims 42 Technology, that for a given appliance, Triple Ohm could even spot variations due to malfunction or wear, warning users about potential issues or hinting that a device is approaching the end of its life.

Reached by eeNews Europe, 42 Technology's managing director Jeremy Carey gave us more details about the company's product roadmap.

"We've built our first version of a 3-phase meter in 2013 with off-the-shelf data-acquisition boards, so at the moment, hardware is quite large but our vision is to integrate it to the size of a match-box so it can fit within a smart meter".

Talking about sampling frequency, Carey justified the 48kHz figure as a design simplification. "You can find plenty of audio chips for data capture at that frequency. We could go to MHz sampling frequencies, but there would be a lot more data to crunch. We need to be able to perform a good separation of data, but with reasonable data loads and processing", Carey said, adding that one option to further reduce the data load may be to sample the harmonics at 12kHz, providing the appliances' profiles can still be clearly differentiated.

Analysing the harmonics within the power line, Triple Ohm identifies the characteristic traces of different appliances.


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