There is a long and somewhat torrid history of using PLC to connect grid assets. In general, it works well for the high and medium voltage lines, and can work well for automated meter reading. This makes PLC quite useful for grid operators, as it can be used to send and receive commands, and also poll meters for their usage. You can see how PLC could be used in smart grid deployments, but there are also many in-home protocols that make use of PLC technologies, such as KNX, X10, HomePlug, and G.hn.
However, using a wireless protocol to do the same provides you with an out-of-band (OOB) channel, which adds a lot of redundancy to the network. If a powerline or substation goes down, so does your communication channel, when using solely PLC. In this regard, the wireless network options make a lot more sense than PLC, despite the (typically) higher installation costs.
The other main consideration is the bandwidth of your communications. On high and medium voltage lines, this is not much of an issue, unless you want to use them instead of the conventional internet as your main backhaul. On the low voltage lines, things get a lot messier and more unpredictable, with radio frequency interference becoming a major problem.
Despite what the name implies, Broadband over Power Line (BPL) does not have a particularly large bandwidth capacity, and so any data intensive application is likely to suffer depending on the size of the network. BPL never took off as a way of delivering actual broadband internet services because of this, as well the RF interference, although some utilities have realized the potential of setting up shop as an ISP – with Chattanooga’s EPB the flagship example. IBM and E.ON do seem interested in resuscitating BPL, though.
There are many PLC implementations that could be used instead of the troubled BPL techniques. The G3-PLC Alliance’s namesake protocol is one of the most advanced, but it has yet to have success in the market. Providing IPv6 (6LoWPAN) capabilities, the approach uses the IEEE 802.15.4 MAC too. It is standardized by the ITU as G.9903.
The alliance was set up back in 2011, originating mostly from collaboration between Sagemcom and Maxim, but the standard itself has only recently begun to be deployed – and not at significant scale. Itron, Landis+Gyr, Sagemcom, and Semtech all hold certifications for G3-PLC, and the latter (better known for its LoRa LPWAN protocol). Based on the alliance’s announcements, Sagemcom’s deal with Enexis was the first post-alliance G3-PLC deployment, back in 2013, but there’s no indication of how extensive the global G3-PLC footprint is.
Separately, the HomeGrid Forum was showing off its roadmap for G.hn, at the IEEE’s International Symposium on Power Line Communications (PLC), aiming to take the protocol (ITU G.9960 and G.9961) from the home and use it in smart cities. In the home, G.hn can certainly achieve the gigabit speeds it claims, but once the distance of transmission increases, all PLC protocols begin to suffer. G.hn is behind G3-PLC in terms of deployments, and hasn’t really gotten the ball rolling. It is hotly tipped as a smart grid technology, but needs to actually gain traction with utilities.
This contrasts with the Wi-SUN Alliance’s announcement that it had passed the 91mn devices mark, not long after it launched its Field Area Network (FAN) certification program in October 2018, and its Enhanced Home Area Network (HAN) certification in March 2018, which added multi-hop and sleep functions to the original HAN profile. The alliance has now grown to 227 member companies too, with 50 joining in the past year.
The FAN protocol is much more focused on the conventional smart grid applications. Based on 802.15.4g, supporting IPv6, it offers a way to create mesh networks of connected devices, which can then use internet-connected nodes in the mesh to transport data back to centralized applications in the cloud. It has a lot of cross-over with smart city applications too, and there will likely be many deployments that began in one area and later transitioned into the other function.
Thanks to using a PHY based on 802.15.4g, and the MAC based on 802.15.4e, Wi-SUN is an open standard, meaning that anyone could make chips for it. This is important for as multifaceted an ecosystem as the utility sector, where customers are very concerned by fears of vendor lock-in. This, and its bandwidth of up to 300kbps, has led to the protocol taking a major foothold in the LPWAN sector – and one that is often overlooked.
Phil Beecher, President and CEO of Wi-SUN Alliance, said “we have been quietly going about our business for many years, but this past 12 months has seen much of this work come to fruition. With higher IoT adoption rates, particularly with smart city and utilities increasingly rolling out applications such as advanced metering infrastructure, distribution automation, and smart home automation, Wi-SUN Alliance members are seeing growing demand for their products.