In April 2011 this author published an article dealing with the threats and potential impacts to the future U.S. Smart Grid from high power electromagnetic (HPEM) threats including High-altitude Electromagnetic Pulse (HEMP) from a nuclear detonation in space over the U.S., Intentional Electromagnetic Interference (IEMI) from terrorists or criminals who may attack and create regional blackouts using electromagnetic weapons, and finally from an extreme geomagnetic storm (initiated by solar activity) that could create damage to the high-voltage electric grid [1]. This author has previously referred to these three electromagnetic environments as a “triple threat” [2].
In this article I will summarize the efforts underway to deal with all electromagnetic threats (including EMC) to the Smart Grid under the Smart Grid Interoperability Panel (SGIP). This author is a participant in this effort and feels there is value in informing those with interests in the EMC field to know the progress of that effort.
This article begins with brief “definitions” of the current power system and the future Smart Grid, followed by an explanation of the SGIP program in general and the EMC activities in particular. At the end of this article some information concerning the approach to determine the appropriate electromagnetic environments for new Smart Grid electronic equipment is provided.
It should be emphasized that the EMC work in SGIP is not finished, and this information should be considered as a “snapshot” of the current situation.
What is the Smart Grid?
The basic electric power grid today consists of basic elements of generation, transmission, distribution and users (residential, commercial and industrial) as shown in Figure 1. Note that the figure indicates the presence of wind power at the subtransmission level and solar panels at both commercial and residential facilities. However, as wind power and solar proliferate and become a higher percentage of power generation, their variability will make it more difficult to keep energy supply and demand in balance. Due to the pressures from many stakeholders, there is a rush to push renewable energy to much higher levels than we have today.
In order to cope with the increased variable power generation and the fact that many of these “power plants” are not always controlled by a control center (e.g., roof top solar systems) there will be a need for more sensors and controls in the power network, both at the transmission and distribution level. It will be important for the utility controlling the voltage and frequency of the network to have situational awareness of the connected power system. This means that new sensors and higher speed communications networks will be needed as shown
in Figure 2.
One of the new types of “sensors” to be used in a Smart Grid is the “Smart Meter” that is electronic in nature and possesses a communications capability to provide information to the power utility with respect to power usage and also where downed power lines may be located due to a storm or other event. These meters are being installed at many locations throughout the country, although the actual design of these meters may vary in different parts of the country.
From an EMC point of view the Smart Grid introduces some new elements that should be considered from an EMC point of view. The design and placement of sensors with varying bandwidths may be affected by the electromagnetic environment present. While the electric power industry is well aware of the severe electromagnetic environment found in high and medium voltage substations, there may not be as much understanding of the appropriate EM environment in a wind farm, or in an industrial manufacturing area. In addition the presence of new transmitters being introduced create the potential of interference. EMC immunity specifications are also not routine in the U.S. for home appliance manufacturers, who may not account for the more complex EM environment present today in the home. Finally the performance criteria for equipment operation in the presence of EM environments are different when there is the need for equipment to communicate without human intervention, in addition to operate.
The SGIP Program
In 2007 NIST was given the “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.” [5] Interoperability is defined by NIST as the ability of diverse systems and their components to work together – it enables integration, effective cooperation, and two-way communication among the many interconnected elements of the electric power grid [4].
In order to provide an open, consensus-based process, an organizational structure was developed known as the Smart Grid Interoperability Panel (SGIP). Figure 3 illustrates the organization of the SGIP with a figure that has been updated to include a new EMC related working group [4,6]. While there are many parts to the SGIP, we are going to focus in the rest of this article on the Electromagnetic Interoperability Issues Working Group (EMIIWG).
The Scope and Tasks of the EMIIWG in SGIP
After considerable discussion and presentation of EMC issues that should be dealt with as part of the SGIP process, the SGIP decided to form a new working group in the fall of 2010. The Chairman of this working group is Dr. Galen Koepke from NIST in Boulder, Colorado. The kickoff meeting of the EMIIWG was held on 1 November 2010. The working group was assigned the following scope and tasks [7].
Scope
This Working Group will investigate enhancing the immunity of Smart Grid devices and systems to the detrimental effects of natural and man-made electromagnetic interference, both radiated and conducted. The focus is to address these electromagnetic compatibility (EMC) issues and to develop recommendations for the application of standards and testing criteria to ensure EMC for the Smart Grid, with a particular focus on issues directly related to interoperability of Smart Grid devices and systems, including impacts, avoidance, generation and mitigation of and immunity to electromagnetic interference. These recommendations from the Electromagnetics Interoperability Issues Working Group can be considered by the SGIP for follow-on activity (PAP creation, SGTCC action, etc.). With its focus on interoperability, this effort is not a general review of electromagnetics and electric power related issues, such as power quality, which are being addressed in different groups outside the SGIP.
Tasks
1. Review potential electromagnetic issues and the existing state of EMC of the power grid and associated systems, including current and proposed Smart Grid enhancements.
2. Segment the Smart Grid devices and systems and electromagnetic environments into a minimal set of categories for which electromagnetic issues and EMC requirements can be identified. These categories should be compatible with the environment classifications of IEC 61000-2-5 where possible.
3. Prioritize or rank the categories in (2) according to the potential impact on Smart Grid reliability. The priorities should consider the extent and severity of possible failures and the availability requirements for the relevant interface as defined in NISTIR 7628.
4. Identify and/or propose EMC terminology and definitions applicable to the Smart Grid and compatible with international standards.
5. Identify and compile the source-victim matrix for each category identified in (2).
6. Identify or develop EMC performance metrics for systems in each category identified in (2).
7. Identify appropriate EMC standards and requirements to meet performance metrics.
8. Identify areas where EMC standards are not available and appropriate SDOs where such standards should be developed.
9. Identify and propose Priority Action Plans to address standards or guidelines in high priority categories if needed.
10. Propose strategic recommendations for EMC of Smart Grid systems, beginning with the highest priority categories. These recommendations should reflect a long-term strategy to maintain EMC as the Smart Grid evolves.
11. Consider the need, and if appropriate, the nature of a conformity assessment program for EMC for coordination with the SGIP Smart Grid Testing and Certification Committee.
In terms of technical progress, the EMC work has been divided into two focus teams: Power Delivery and Power Customer. The separation point is the customer meter. The two teams are contributing to a report to the SGIP that will identify and recommend existing EMC standards that are appropriate for the various equipment locations and will further identify standards that are not adequate or even available for the purposes of Smart Grid. It is planned that the recommendations from the EMIIWG will be included in the next release of the SGIP Framework.
It is beyond the scope of this paper to discuss all of the items in the task list, but instead the focus will be on task 2, which involves the determination of the appropriate EM environment for Smart Grid equipment.
The Electromagnetic Environment
One of the key aspects to the work of the EMIIWG is to determine whether adequate EMC immunity standards exist for future Smart Grid equipment that are consistent with the electromagnetic environment where they are intended to operate. As this author was a member of IEC TC 77/WG 13 that prepared Edition 2 of IEC 61000-2-5, “Description and classification of electromagnetic environments” [8], some discussion of the approach taken is presented here.IEC 61000-2-5 Edition 2:
• Provides information about EM phenomena expected at different locations
• Introduces the approach to describe electromagnetic phenomena by their disturbance degrees
• Classifies the EM environments into different types of locations and describes them by means of attributes
• Compiles tables of disturbance levels for EM phenomena that are considered relevant for those types of locations.
The location classes in Edition 2 of 61000-2-5 have been consolidated to three locations including Residential, Commercial/Public, and Industrial. Edition 1 defined more locations, but it was decided to provide more detailed environments for fewer locations. Also in the IEC there is a separate EMC generic specification to cover power system electronics, IEC 61000-6-5 [9]. It is likely that IEC 61000-2-5 will be more applicable to the power customer aspect of the EMIIWG, while IEC 61000-6-5 and other IEC and IEEE product standards will be more applicable to the Power Delivery aspect of the work. As progress has been more rapid on the power customer side of the Smart Grid problem, the remaining discussion will only cover the environment information in IEC 61000-2-5.
The process used in IEC 61000-2-5 involved three major steps:
1) Define the location classes with regard to the types of exposures (both conducted and radiated) and the distances expected from particular types of emitters.
2) Compile a comprehensive list of radiated and conducted phenomena and disturbance levels along with formulas to compute field levels where appropriate (include formulas for near-field exposure).
3) Combine the results to develop recommendations for disturbance levels for a given “location” for all applicable phenomena.
Figure 4 illustrates this process in graphical form.
It should be mentioned that two main improvements were made with regard to phenomena in IEC 61000-2-5 Edition 2. The first was to ensure that all conducted phenomena were updated since the last edition fifteen years ago, to include for example, more recent power harmonic environments due to switched mode power supplies. In the area of radiated phenomena, significant work was done with the support of ITU-T to keep up with new broadcast services (frequencies and power levels) and other radio services such as RFID.
While the process to identify the appropriate EM environments, immunity test standards and equipment performance criteria when tested are well underway in the EMIIWG for both the power customer and the power delivery aspects of the EMC problem, the results are not yet final. It is expected that after the EMIIWG report is finalized and sent to the SGIP, then further details can be provided to interested readers.
Summary
This article has presented some background to the problem of EMC and the Smart Grid in the United States. The SGIP program and the scope and tasks of the EMIIWG have been summarized for the reader. Links are provided in the references for those who have interest to explore further. This article also discusses the approach used by the EMIIWG to develop an understanding of the EM environment that would be present at locations where Smart Grid equipment may be placed, so that it will be possible to determine the adequacy and availability of EMC immunity test standards for the Smart Grid Program.
References
[1] Radasky, W. A., “High Power Electromagnetic (HPEM) Threats to the Smart Grid,” Interference Technology EMC Directory and Design Guide, April 2011.
[2] Radasky, W. A., “Protection of Commercial Installations from the “Triple Threat” of HEMP, IEMI, and Severe Geomagnetic Storms,” Interference Technology EMC Directory and Design Guide, April 2009.
[3] Olofsson, M., A. McEachern and W. Radasky, “EMC in Power Systems Including Smart Grid,” APEMC, Jeju Island, Korea, May 2011.
[4] http://www.nist.gov/smartgrid/nistandsmartgrid.cfm
[5] “The Energy Independence and Security Act of 2007,” U.S. Public Law 110-140.
[6] Koepke, G., “NIST Smart Grid Framework and the SGIP EMII Working Group,” Tutorial Presentation at the IEEE International EMC Symposium, Long Beach, California, August 2011.[7] http://collaborate.nist.gov/twiki-sggrid/bin/view/SmartGrid/ElectromagneticIssuesWG
[8] IEC 61000-2-5 Edition 2, “Description and classification of electromagnetic environments,” International Electrotechnical Commission, May 2011.
[9] IEC 61000-6-5, “Immunity for power station and substation environments,” International Electrotechnical Commission, July 2001.
Dr. William A. Radasky, Ph.D., P.E., received his Ph.D. in Electrical Engineering from the University of California at Santa Barbara in 1981. He has worked on high power electromagnetics (HPEM) applications for more than 43 years. In 1984 he founded Metatech Corporation in Goleta, California, which performs work for customers in government and industry. He has published over 400 reports, papers and articles dealing with transient electromagnetic environments, effects and protection during his career. He is Chairman of IEC SC 77C and IEEE EMC Society TC-5. He is an EMP Fellow and an IEEE Life Fellow.
Dr. Radasky is very active in the field of EM standardization, and he received the Lord Kelvin Award from the IEC in 2004 for outstanding contributions to international standardization. He served as Chairman of the IEC Advisory Committee on EMC (ACEC) from 1997 to 2008. He is currently working with the EMC Working Group commissioned by the Smart Grid Interoperability Panel (SGIP) to evaluate the performance of Smart Grid communications in the face of everyday EM environments and interference caused by HPEM threats.
