Thanks to The Florida Channel, today I listened to a September 20 Florida Public Service Commission “smart meter workshop”.
The state’s power utilities presented their cases for deployment of smart meters. I was surprised to learn that all of the smart meter systems in Florida rely upon wireless communication. Florida Power & Light uses a 900 MHz mesh network: each meter transmits encrypted data only when polled; any meter may become a repeater within the network. The data exchanged with each meter are minimal and infrequent. Dynamic pricing data may be uploaded to each meter and load management is optionally available.
FPL’s smart meter video:
I just wish that they had used their existing copper wires to carry signals, rather than wireless. Every meter is already connected by large gauge copper wire and transformers to its power utility. Why not use those power lines to communicate consumers’ metering data? That way, each utility need maintain only their wires, not wired plus wireless systems.
My first rule of electronic communication is, “Wireless should be your last choice, not your first choice.” Wireless communication uses precious RF spectrum, degrades reliability, and exposes content to theft.
Most utilities already use power line carrier (PLC) to provide internal protection, control, and metering (PCM) communication. PLC is a reliable medium. Yes, signal coupling capacitors must be installed across fuses and circuit breakers so that the RF carrier isn’t interrupted when the device opens during a fault event, and decoupling chokes (inductors) are needed to strip off the RF carrier occasionally. I’m surprised that the utilities wouldn’t wish to leverage this well-known communication technology and receive more return on installed outside plant.
They’ve chosen a 900 MHz wireless medium instead. Apparently the Florida PSC approved the wireless deployment.
The existing electric power distribution system is a noisy one for transport of data, I’m sure. Harmonics of 60 Hertz, switching transients, and uncontrolled line impedances must be overcome. I’m disappointed that neither system vendors nor utilities seem to have developed a viable wired solution. I’ll see if EPRI (Electric Power Research Institute, a consortium of power utilities) has researched this. I wish that the PSC had leaned on FPL a bit more to encourage use of PLC for smart meters.
I smugly thought, “This doesn’t concern me. I have an old analog meter.” Then I walked outside and just to be sure, peered at my FPL meter. It’s brand-new and wears an FCC ID tag, marking it as a smart meter. A wireless smart meter.
Excellent smart meter info: http://www.arrl.org/electric-utility-communications-applications-and-smart-grid-technologies
Questions about FPL’s smart meters: http://smartmetermatrix.org/
23 Dec 2012 Addendum: I’ve re-considered my stance. Relying upon the existing electric wires for communication is equivalent to in-band signalling; if an electric wire is cut, control and communication fails as well. I’m not enthused about using a wireless medium for control and communication, but I endorse the idea of using out-of-band signalling. Since no alternative out-of-band medium exists, wireless is our only choice.