The smart meter should not serve as the primary gateway for in-home devices – where gateway is a device that provides network connectivity between two networks and that may also provide application level connectivity between devices and/or applications. The most common example of this architecture is a smart meter with an AMI communications radio and a separate ZigBee radio for home area network communications – however, in this architecture the separate communications capability for home area network communications could be any technology, not necessarily ZigBee .
There are several primary risks with a meter-as-gateway architecture. The historical rate of technology change in other emerging technologies from the IT and computing industries as well as the existing track record for HAN technologies suggests that technology obsolescence of the home area network communications technology is a significant risk. The lifecycle for home area network technologies can be as short as 1/10th the product life of a smart meter – thus physically coupling these two communications technologies “under the glass” will lead to only one of two scenarios: increased costs to update the meter in order to keep pace with the evolution of HAN technology or hinder the rate of innovation in the HAN by not updating the meter to keep pace with HAN technology. Second, poor connectivity between the smart meter and home area network devices may reduce program efficacy, such as time-of-use programs, that utilize enabling technologies such as a PCT. Lastly, selecting a single HAN technology to embed in the smart meter - where the smart meter is the primary gateway for price, usage, and demand response information – will limit market diversity and will hinder innovation. The effect of this architecture not only limits the ability of the HAN market to effectively address consumer demand (for example, the consumer would like Technology A, but the meter only supports Technology A) but also limits the consumer’s ability to receive information through alternative methods.
The role of the smart meter with respect to the home area network should be to provide near real-time meter data access (e.g. on the order of minute-by-minute data) to the consumer -- “meter-as-server” rather than “meter-as-gateway”. Meter data access within the HAN should be considered separately from gateway functionality, despite often being combined into a single discussion around embedding home area network communications into a smart meter.
A gateway to in-home devices should be provided through a dedicated standalone device (similar to a consumer Internet gateway) or embedded in an in-home device such as a programmable communicating thermostat. An external gateway could utilize the AMI network or an alternative network such as the Internet – the discussion of the physical location of the HAN gateway should not be confused with the network to transport the information to the HAN. Utilizing an architecture where the HAN gateway is external to the smart meter has numerous benefits in addition to addressing the risks associated with the meter-as-gateway architecture. First, an external gateway decouples the evolution HAN technology from smart meter, thus avoiding meter replacement to upgrade to future HAN technologies.
Even if smart meters provide over the air upgradeability, they will have limited future extensibility due to physical hardware constraints. Second, a smart grid deployment that utilizes an external HAN gateway allows for a lower total deployment cost compared to a smart meter that includes a HAN gateway, assuming reasonable assumptions for technology lifecycles, meter replacement costs, and technology adoption by consumers. External HAN gateways allow the utility to continue a deploy-as-you-go approach for individual consumers as they adopt new programs – this not only minimizes costs to the utility but provides consumers access to HAN technology at its natural rate of innovation . This external HAN gateway architecture is more cost effective approach compared to deploying the HAN connectivity in every meter – where only a fraction of the households are likely to adopt new programs like technology-enabled demand response. Third, an external HAN gateway can potentially address connectivity issues with the meter since it can be located in a more central location in the residence. Lastly, an external gateway architecture enables market innovation by allow energy service providers, regardless of deregulation, to utilize the most appropriate technologies demanded by consumers – rather than artificially constraining all HAN devices to utilize the HAN communications technology embedded in a meter.
Finally, the application of a user-removable communications module is a complementary architectural component – in addition to HAN gateways external to the smart meter – that address the risks of the meter-as-gateway architecture. The USNAP specification and USNAP modules (http://usnap.org) provide a communications protocol agnostic method to enable smart grid connectivity to in-home devices. While not an architecture in of itself, this open standard facilitates innovation in HAN devices by decoupling the communications from the HAN device and facilitating market innovation
No comments:
Post a Comment