This page was created for ARRL by ARC Technical Resources, a consulting company with expertise in EMC testing, EMC Standards and grid automation. (Updated 1/2012)
A tutorial on the operation of the electrical distribution system (Electricity 101) is available from the US Department of Energy (DOE.)
The modernization of the electric power grid, often called "smart grid" by its proponents, is an important goal. Efforts such as the Advanced Metering Infrastructure (AMI), Automated Meter Reading (AMR) and the other phases of intelligent grid management are all part of the smart grid. Having better control of the power grid will improve its reliability and efficiency and, as applications are developed for end users, point-of-use monitoring and control of power usage will benefit utilities by reducing peak loads and benefit consumers by providing a way to save on their energy costs by reducing their peak usage.
In grid-automation applications, the control system forms the core of the design with the communications media being a secondary consideration that can be implemented in a number of ways. Each technology has advantages and disadvantages and each is "best" for some circumstances. Because of the complex layout of the power grid and the various equipment connected to it, a hybrid data-communications media mix will necessarily avoid a "one-size-fits-all" approach. It is a generally accepted engineering principle, however, that control of a system should be designed to be as independent of that system as possible, to ensure that system failures (ie, power outages or dropped lines) do not also result in loss of control of the system at a time when control may be needed the most.
Many of the techniques used to send information to and from the power grid have been shown to avoid widespread inteference problems. If an electric utility is implmenting grid automation, this does not necessarily mean that there will be interference. If a utility uses a technology that does not cause interference, or if operating a BPL system runs it at the correct power levels with notching in the Amateur bands, grid automation hardware can operate without widespread interference problems. BPL can and does play a role in grid automation, especially for the in-premise part of these systems. Other media will also be used.
History of Grid Automation
In the spring of 2000, the Pacific Northwest National Laboratory began work on the future direction of the power grid and transmission system to try to understand and shape the direction of the newly emerging technologies of distributed energy resources, load management, automated power diagnostics and solid-state controls. Information technology (IT) was seen as the key enabler for transforming the electric power system.
The Power Grid Problem
In April of 2003, 65 representatives from the electric utilities, equipment makers, IT providers, regulators, interest groups, universities and laboratories met to build a “roadmap” for the future of the US electric power grid. The common vision discussed at these meetings is presented in Grid 2030 from the DOE. Their major findings:
- America’s electric system is aging, inefficient, congested and incapable of meeting the requirements for clean power in the up-coming Information Economy.
- Risk and uncertainty in the electric industry have driven investment to an all-time low.
- Regulations designed to encourage competition have fallen short of expectations.
- Several promising technologies could address problems in system operation.
- The Information Technologies that have transformed other “networked” industries (like telecom) haven’t transformed the electric industry yet.
- The proliferation of microprocessors requires greater power quality and reliability.
- It is increasingly difficult to site transmission lines, thus requiring new power electronic solutions that allow more power flow through existing lines (Flexible AC Transmission Systems, or FACTS) and local (distributed) generation.
The “technology readiness” of our critical electric systems needs to be improved.
- The “political logjam” should be eliminated to reduce uncertainties and encourage long-term investment.
- R&D should be expanded so that any new equipment installed will include the latest technologies.
- A collaborative “technology roadmap” needs to be developed to guide R&D and demonstration projects.
The US Dept. of Energy “Smart Grid” is one of the names given to these efforts. The DOE has identified these seven characteristics of a modern “smart grid:”
- Self-healing from power disturbances
- Enables active participation by consumers in “demand response”
- Operates resiliently against physical or cyber attack
- Provides power quality for 21st century needs
- Accommodates all generation and storage options
- Enables new products, services, and markets
- Optimizes assets and operational efficiency
Standardized architectures and interfaces will stimulate developments towards the interoperable “smart grid” of the future.
The “GridWise Alliance” is a public/private consortium to help integrate electricity infrastructures, processes, devices, information and markets so that electrical energy can be generated, distributed and consumed more efficiently and cost effectively. The Alliance identified the challenges facing the electricity industry in realizing the goals of their GridWise program:
- Utilize information technologies to revolutionize energy systems like many other businesses
- Develop technology solutions that cross enterprise and regulatory boundaries to bring value
- Enhance grid security and reliability with flexible and adaptive information processes
- Enable consumers to benefit by interacting with the grid
In 2004, the GridWise Architecture Council was formed to shape the architecture of an interactive electric system. Its role is to help identify areas for standardization that allow significant interoperation between electricity system components. The basic technologies that would enable an intelligent power grid are available today. Their integration into compatible systems is the challenge.
Also in 2004, the Electric Power Research Institute (EPRI) published their “IntelliGrid” architecture; the first comprehensive technical framework for linking communications and the power grid in the “smart grid” envisioned earlier. The architecture features common security, network and data communications infrastructure that is used as newer types of intelligent grid equipment come on-line. To help smooth these transitions, EPRI has proposed an “architected approach to integration” by deploying equipment in this order:
- Automatic Meter Reading (AMR) implementation enables energy markets and time of use pricing
- Utility information (SCADA) uses the AMR infrastructure to manage outages & demand (loads)
- Remote-controlled distribution devices automate restoration and enable distributed generation
The Galvin Electricity Initiative was launched in 2005 in response to the massive East Coast blackout of August 2003. Its aim was to create a power delivery system that is environmentally sound, fuel efficient, resilient, and robust. It should withstand natural and weather-related disasters and mitigate the potential damages caused by terrorist attacks.
The National Energy Technology Laboratory (NETL), a DOE national laboratory, issued their Smart Grid Implementation Strategy (SGIS) to accelerate the modernization of the electricity grid. These four milestones (below) break down the implementation into manageable “chunks”. By sequencing these milestones, a more cost effective modernization program is achievable.
1) AMI – Advanced Metering Infrastructure; Initially, Automated Meter Reading (AMR) technologies were deployed to reduce costs and improve accuracy. The value of two-way communications between power providers and customer loads lead to the evolution of AMR into AMI. It includes smart meters for advanced measurement, an integrated two-way communications infrastructure including control of loads, (demand response) an active consumer interface, (may be part of the thermostat or elsewhere) and a meter data management system to process the data. This communications infrastructure is critical for the other three milestones.
2) ADO – Advanced Distribution Operations: The ADO milestone uses AMI communications to collect distribution information and improve operations, providing the increased information and control needed for a self-healing grid. ADO includes sensors, distributed intelligence, outage management capability, and distribution automation technologies. The ADO milestone supports the Advanced Transmission Operations milestone.
3) ATO – Advanced Transmission Operations: The ATO milestone aims at improving transmission reliability and efficiency, while managing congestion on the transmission system. ATO includes substation automation, advanced protection and control, modeling, simulation and visualization tools, advanced grid control devices (such as “flexible AC transmission systems” or FACTS) and materials, (such as superconductors) and their integration with distributed generation markets. (wind, solar, hybrids, storage, etc.)
4) AAM – Advanced Asset Management: The AAM milestone is for improving the utilization of transmission and distribution (T&D) assets and more effectively managing these assets’ life cycle. AAM requires “smart sensors” to provide operational and asset condition information to significantly improve asset management.
Under the Energy Independence and Security Act (EISA) of 2007, the National Institute of Standards and Technology (NIST) has "primary responsibility to coordinate development of a framework that includes protocols and model standards for information management to achieve interoperability of smart grid devices and systems…" In April of 2009, NIST announced a Three-Phase Plan for Smart Grid Standards. Effective interoperability is built upon a unifying framework of interfaces, protocols, and consensus standards. The newest release, (Smart Grid Interoperability Standards Framework, Release 2.0) was issued in October, 2011.
An AMI system is comprised of a number of devices and applications that are integrated to perform coherently. Programmable "smart meters" will replace the electromechanical Watt-Hour meter familiar to most of us. These "smart meters" will allow:
- Time-based pricing
- Consumption data exchange
- Network metering
- Loss and Restoration notification
- Remote on/off
- Load limiting for “bad pay” or demand response (load control)
- Energy Pre-payment
- Power Quality monitoring
- Tamper and Theft protection
- Communications with other intelligent devices
Greater efficiency is realized as information feedback alone has been shown to cause consumers to reduce their energy usage. See the ARRL Smart Meter page for more information.
Home Area Networks are consumer portals that link “smart meters” to controllable electrical loads. (“Smart appliances”) Its functions can include:
- In-home display
- Responsive to price signals based on consumer-entered preferences
- Set points that limit utility or local control to within consumer-set limits
- Control of loads without continuing consumer involvement
- Consumer over-ride capability
On the utility side of the meter, a Meter Data Management System analyzes information to be fed to other utility systems called Operational Gateways. It validates the incoming AMI data to ensure that its output to the Gateways is complete and accurate, despite communication disruptions or customer premises problems. Operational Gateways are utility system computer networks that receive validated metering information to support the tasks of each of the “milestones” above; ADO, ATO and AAM.
The AMI Integrated Communications Infrastructure (including Access BPL and its alternatives) supports interaction between the utility, the consumer portal and any controllable electrical loads on the Home Area Network. (The Smart Grid Information Clearinghouse also has information on Integrated Communications) It must employ “open” (non-proprietary) bi-directional, encrypted communications and is the foundation of all modern grid functions. Supporting media must accurately and securely transmit information at the required speed with the required throughput. Future application bandwidth requirements should be considered when choosing media. Various architectures can be used, the most common being local “concentrators” that collect data from groups of meters and transmit that data to a central server via a “backhaul” channel. Various media can provide all or parts of this typical architecture.
The Choices in Media
|Power Line Carrier (PLC)||
|Access Broadband over Power Lines (Access BPL)||
|In-premises BPL (HomePlug)||
|In-premises BPL (HomeGrid Forum)||
|Multiple Address System Radio||
|FHSS Spread Spectrum Radio||
|TDMA Wireless (Cellular)||
|Internet Protocol (IP)||
|Fiber to the Home (FTTH)||
|Hybrid Fiber Coax (HFC)||
Communications Media Impacts on Amateur Radio
Power Line Carrier (utility side of meter)
Utilities have been using narrow-band (single carrier) Power Line Carrier (PLC) operating below 500 kHz as a control technique for many decades without interference complaints, but the limited bandwidth of this media would seem to constrain its use to SCADA substation control. Newer broadband (multi-carrier) PLC implementations offer better bandwidth, but are mostly used for in-premises applications.
AMI & Backhaul Media (utility side of meter)
BPL is a double-edged sword as far as interference with the Amateur service is concerned. Modern Access BPL systems that operate at or under the US limits and employ 35dB notching of locally-used spectrum have been shown to be mostly interference-free. Those same systems operated at the same levels with only the mandatory 20dB notching can have more problems. Single-ended coupling results in higher emissions than differential coupling, but is still used most often. Access BPL (for backhaul) will succeed only if it is commercially viable and doesn’t cause interference complaints. The interference issue can be addressed through careful deployment (and the adoption of meaningful EMC Criteria in the P1775 Standard for BPL), but the larger questions remain concerning the required make-ready and keep-ready work on the lines, poor latency, slow speeds and limited distance. The signal must overcome the MV line’s sparking “gap noise” or the data packets will crash. (See ARRL AC Power Interference Handbook for mitigation of gap noise)
Copper unshielded twisted pair (UTP) telephone lines and optical fiber don’t have a history of causing interference with the Amateur service. Neither do the Multiple Access System Radios nor Paging Networks currently deployed.
Frequency-hopping Spread Spectrum (FHSS) Radio uses the 902-928 MHz UHF band, which is also used by Amateurs, mostly operating on NFM. There have been some reports of interference, but the band is not heavily utilized. This has been a popular choice for AMI (“smart meter”) deployments since it is unlicensed.
WiMAX is a microwave backhaul media that can be used in point-to-point or point-to-multipoint configurations based on the IEEE 802.16 standard. It covers 10-30 miles and typically uses licensed spectrum (although it is possible to use unlicensed spectrum) to deliver a point-to-point IP connection from the utility to the wireless termination point in the neighborhood using 802.16d.
Combinations of the above backhaul media in an integrated communications system are the most likely future scenario. WiMAX (microwave) signals may not traverse well in tall, urban centers, so fiber or Access BPL to the large buildings may perform better. Remote locations will surely employ a different mix of local AMI and backhaul media. In any case, an integrated utility communications system employing open Standards and the appropriate media will be required for modernizing the power grid. On the utility side of the meter, IP-capable (standardized and encrypted) backhaul is desirable to utilities for handling metering and control data.
Home Area Network (HAN) Media (customer side of meter)
WiFi uses the 2.4GHz unlicensed band and hasn’t caused notable interference, other than local digital noise problems similar to those from personal computers. (See ARRL RFI Book3 or on-line materials for mitigation)
ZigBee in the U.S. uses the unlicensed 2.4 GHz band at low power and appears to have minimal interference potential for Amateurs. Narrow-band ZigBee-enabled “Smart Meters” can mesh network themselves with smart appliances or other nearby ZigBee gas or electric meters to exchange or forward data.
HomePlug Powerline Alliance certified devices offer broadband connectivity over in-premises powerline wiring using OFDM technology with the amateur bands notched in the silicon.
HomeGrid Forum (G.hn) certified devices offer broadband connectivity over in-premises powerline, coax or phone wiring using OFDM technology with the amateur bands notched in the firmware.
Open Source Home Area Network (OSHAN) is a 900MHz narrow-band open-source network specification (kernel) for Home Area Networks. It supports Enhanced IEEE 802.15.4, IP Addressability (6LoWPAN / IPv6) and the Smart Energy Profile (SEP) 2.0
Internet Protocol (IP) will have a place in the customer-side media mix. (Using the customer’s existing connection to the premises) It will be a convenient portal for consumers to interact with the electric utility (or third parties) and program their controllable loads. The same could be said of Internet2 at higher speeds.
The NETL summarizes in their Integrated Communications white paper that “Achievement of the modern grid vision is fully dependent on integrated communications technologies. Without a modern communications infrastructure… the modern grid cannot become a reality. Integrated communications will open the way for the other key technology areas to be accepted and implemented, leading to the full modernization of our power grid.”
Selected Articles about BPL and Smart Grid and a Smart Meter FAQ page are available. SmartGrid.gov is the information gateway on Federal smart grid initiatives. Projects are searchable. The Smart Grid Information Clearinghouse smart grid project page allows you to find smart grid projects in the United States. In Europe, the IEC maintains a Smart Grid page and a Smart Grid & EMC page.
Smart Grid Companies & Consortia
Cooper Power Systems
HomePlug Powerline Alliance
Sensus Metering Systems
Silver Spring Networks
Universal Powerline Association (suspended 11/2010)