The Network as the Enabler of Smart Grid
The objective of smart grid projects is to modernize the grid in order to improve its reliability while reducing gas emissions and costs. These projects involve a host of devices and associated applications that will be deployed across the next two decades.
The communication infrastructure has a key role in enabling smart grid deployments and should be carefully designed in order to avoid bottlenecks and other issues as discussed in this article.
The smart grid, in many ways, replicates processes that we have already experienced in the IT industry and can learn from:
-Migration from centralized computing (= generation) to distributed computing (= distributed renewal energy generation)
-Shift from stand-alone PC ( = off-net substations and devices) to a network of computers ( = on-net substations and distribution automation devices)
-Convergence (News - Alert) of proprietary network protocols (LAT, DECNET, SNA, NOVEL, DNP) to a standard protocol (TCP/IP)
-Shift from narrow band text applications ( = mechanical meters) to high bandwidth GUI applications (= digital smart meters and panels)
-Increase in network capacity from a few Kbits to dozens of Mbits
AMI – The Initial Smart Grid Network
Smart metering is known as the first smart grid application and has become so for a variety of reasons. It allows the utility to establish a dialog with its consumers and help shave the peak consumption, which is a source of multiple issues. Providing electricity during a period of peak consumption requires utilities to use expensive fuels or buy power at a high rate. It also creates outages, which has a negative impact on their SAIFI and SAIDI indexes, and may create operation issues that result in OPEX (News - Alert) expenses and loss of revenue.
During the past two decades, such outages have increased by 124 percent in North America -- up from 41 blackouts between 1991 and 1995, to 92 between 2001 and 2005, according to research at the University of Minnesota. In the most recently analyzed data available, utilities reported 36 such outages in 2006 alone.
Due to the compelling benefits of smart meter deployment and the ease of measuring its deployment progresses, governments around the world have mandated smart meter deployments and have provided stimulus funding to support this effort.
The market for AMI (Advanced Meter Infrastructure) is expected to grow in North America at a rate of 10 million smart meters a year, beyond the 16 million smart meters already installed by 26 utilities in 15 states.
AMI networks were designed to support smart meter connectivity requirements which are typically characterized by low bandwidth and high latency. Good enough for smart metering applications but not necessarily for the next smart grid applications that require a 4G wireless network that supports real-time, quality of service (QoS), broadband and mobility.
The New Smart Grid Applications
It is hard to predict what “new” smart grid applications we should expect in the next decade, in the same manner that it was almost impossible to predict that Google (News - Alert), Amazon or eBay would happen, back in the early 80’s when the Internet took a shape and form while the main applications were text email and FTP.
Yes, we already know that some grid automation applications require low-latency and QoS that is not available by most AMI solutions. We also understand that bandwidth is going to be a requirement to allow for video surveillance applications that will help protect the grid assets and provide visibility to issues before the line truck crews arrive to the scene. Broadband may also be required in emergency cyber security situations, when the utility needs to instantly update software to millions of devices.
It would be reasonable to assume that a new market of reach-GUI applications using the in-home smart grid panels as terminals will evolve. The question is how much bandwidth will these applications require and will the smart grid networks that are being deployed today be able to support it.
Smart grid network requirements
The network infrastructure has a key role in the success or the failure of the smart grid project. Imagine what would be the value of commercial internet applications if the network infrastructure supporting it would not be reliable or have enough bandwidth?
The same goes for the grid applications and the network supporting it. The network must be reliable and secured, with the necessary performance capabilities, interoperable and scalable for future requirements.
WiMAX (News - Alert) is the only commercially available 4G network that can support all four requirements of low latency, QoS, mobility and broadband, and has become a standard de-facto for smart grid WAN connectivity in North America.
Extending AMI to 4G Smart Grid WAN
The initial smart grid network is typically the AMI that covers the “last mile” and supports the smart metering project. The second phase of smart grid projects is typically grid automation which is spread across the distribution grid and requires a 4G WAN (Wide Area Network), often described as the “middle mile.”
The line that separates the last mile and the middle mile is drawn by the utility and is impacted by the smart grid applications. Grid automation applications that require low latency and QoS or high bandwidth, must fall into the 4G WAN middle mile, while some monitoring applications with no special latency and bandwidth requirements may be located as part of the AMI last mile network.
Another approach, lead by GE, that has been successfully deployed in Australia and is in pilot phase in North America is to combine the last mile and middle mile into a single 4G WiMAX network, eliminating the concern of network latency or bandwidth limitations.
When selecting the two tier approach, last mile and middle mile, it is imperative to ensure a unified management of the two networks and maintain the ability to “move” the line that separate the two networks, according to the utility smart grid application requirements.
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As the smart grid market begins to mature, utilities realize that AMI networks cannot be extended to support grid automation applications, which is the typical second phase of smart grid projects. 4G WiMAX is gradually becoming a standard de-facto in North America for smart grid WAN, providing backhaul to the current AMI deployments and connectivity to grid automation applications that require low latency, QoS, high bandwidth and mobility.
Edited by Erin Monda