Executive SummaryA key mission of the U.S. Department of Energy (DOE) Office of Electricity Delivery and Energy Reliability (OE) is conducting research and development to enhance the security and reliability of the nation's energy infrastructure. Improving the security of control systems, which enable the automated control of our energy production and distribution, is critical for protecting the energy infrastructure and the integral function that it serves. The DOE-OE Control Systems Security Program is actively pursuing advanced security solutions for control systems.The focus of this report is analyzing how, where, and what type of wireless communications are suitable for deployment in the electric power system and to inform implementers of their options in wireless technologies. The discussions in this report are applicable to enhancing both the communications infrastructure of the current electric power system and new smart system deployments.The work described in this report includes a survey of the following wireless technologies: In this document, we provide a concise summary of the technical underpinnings of each wireless technology. We also outline the feature set and the strengths and weaknesses of each technology. Our intent is to provide enough detail to our readers such that when considering wireless for a particular application, they will know enough to ask the right questions to get the features and capabilities desired.For obtaining data communications coverage quickly and inexpensively over a large geographic area, both WiMAX and 3G/4G cellular technologies should be considered. WiMAX at the present holds a bandwidth and latency advantage over 3G cellular communications; however, with the imminent LTE deployment from multiple carriers, we believe this advantage will be short-lived. Unlike WiMAX deployments, LTE will mostly reuse existing cellular networks and should be a straightforward evolution of the 3G cellular networks. Both of these technologies operate over licensed spectrum and therefore should be protected against unintended interference. In terms of scalability, we know that the cellular networks are capable of accommodating hundreds of millions of subscribers while providing both voice and data communications. WiMAX networks have been deployed to provide wireless local loop service successfully. However, presently, WiMAX networks only support a small fraction of users compared to 3G cellular networks. Whether using WiMAX or 3G/4G cellular, we recommend a combination of application-level security and virtual private networking (VPN) for transporting electric power system information over these public networks.For creating a wireless sensor network for both data gathering and command/control applications, there are three alternatives, all based on the IEEE 802.15.4 protocol stack: ZigBee, WirelessHART, and ISA100.11a. We expect ZigBee to be a common choice for electric power system networking within the iv home. While there are legitimate concerns for the security properties of ZigBee ...
This version is available at https://strathprints.strath.ac.uk/61522/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the All conventional techniques for measuring frequency result in large deviations to the perceived or calculated frequency when the AC waveform undergoes a phase step. The deviation magnitude and duration are dependent on the phase step magnitude, and the applied windowing/filtering. Such phase steps do occur in the power system, and the erroneous frequency calculation can result in inappropriate reactions by some rapidly-responding control and protection systems. If the frequency measurand is further differentiated to ROCOF (Rate of Change of Frequency), the excursion magnitudes can become far larger than any normally expected values of ROCOF. This paper discusses the meaning of the terms frequency and ROCOF, and presents a modified concept of frequency and ROCOF. This is done by allowing rapid phase steps to be disaggregated from frequency in the AC waveform model equation. This allows new measurands "underlying frequency", and "underlying ROCOF" to be defined, as a pair of linked parameters, independent from a separate dynamic phase parameter. These new measurands have the potential to offer much more useful and stable information to be sent to fast-acting control and protection systems, than the existing measurands of AC frequency and ROCOF, particularly during fault events and large switching or disconnection events. Keywords-Frequency estimation, Power System Control, Power System Faults, Power system protection, Power system reliability, Rate of Change of Frequency I. PHASE STEPS IN THE POWER NETWORKSOn 16 August 2016 a major fire broke out in the Cajon Pass in southern California. It impacted several high-voltage transmission lines in the area, and caused the loss of nearly 1200 MW of generation. Some of the generation loss was triggered by a phase jump that caused the "calculated frequency" to cross a level that required the generation (photovoltaic) to relay out. Fig. 1, adapted from [1] shows the three phase voltage waveform, with two times at which abrupt phase shifts took place. The first of these, just before t = 0 in the figure, occurred as a result of a phase-to-phase fault on the transmission circuit.The voltages of the two phases become one at the instant of the fault, and rap...
Power systems for undersea observatories combine ideas from terrestrial power systems and switching power supplies with experience from undersea cable systems. Basic system tradeoffs for various design decisions are explored in this paper. First, design questions including whether the power delivery should be alternating or direct current and a parallel or series network are examined. This introduces the question of maximum power delivery capability, which is explored in depth. A separate issue, the negative incremental resistance presented to the delivery system by the use of constant-voltage converters, is examined, and the resulting dynamics explored by simulation.
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