This month, authors from the National Renewable Energy Laboratory (NREL) and NIST released a technical report on the Use of Traveling Wave Signatures in Medium-Voltage Distribution Systems for Fault Detection and Location. The theory behind the work is that sensitive and time-synchronized voltage and current measurements can be used to detect electromagnetic signatures emitted by electrical faults somewhere in an electrical distribution system.
Traveling wave analysis applied to sensor measurements from multiple sites, combined with the spatial-temporal characteristics of these signatures, help identify the type and location of electrical faults. The technique requires advanced measurement and analytical capabilities that are not yet commonly deployed in power systems. However, this approach to system monitoring will allow utilities to identify and locate intermittent and small magnitude faults that have traditionally been difficult to diagnose. Moreover, such faults may become more common as electric grids increasingly rely upon distributed energy technologies and inverter-based resources.
The research described in the report is a culmination of years of study, modeling and simulation, development of test equipment, and testing in laboratory and field environments. The research initially began at NIST with an exploratory project to evaluate synchronized sampling requirements for traveling wave fault localization in distribution systems. NIST researchers investigated propagation characteristics and analyzed sensor performance to the limits of their organizational capabilities, but lacked the infrastructure to validate fault detection and localization. To continue development, NIST researchers partnered and collaborated with NREL and invented and transferred technologies that were used to experimentally produce and measure traveling waves in distribution lines.
Traveling wave fault detection is already used in the relatively simple physical networks of the high-voltage transmission system. However, this collaborative project systematically addressed the specific challenges of applying traveling wave fault detection to electrical distribution systems with more interconnections and dynamic power flows. The resulting technical report covers methods to improve modeling and simulation, feature detection, sensor and algorithm validation, and documentation of tests performed on actual distribution circuit segments.
Consider the thermostat. It controls the temperature in a room by measuring temperature changes and actuating heating or air conditioning, writes NIST's Avi Gopstein in "An Introduction to the NIST Smart Grid Interoperability Framework," published in EE T&D Magazine (p. 14), 2nd Quarterly Issue of 2021. Now consider a communication-enabled smart thermostat that is interoperable with other systems, Gopstein also writes. Such thermostats could:
Gopstein describes the increasing need for grid interoperability and its potential. In 1970, the U.S. electric grid had 4,500 generators connected to it, with just over 200 new ones added annually. Today, over 80,000 generators are connected to the U.S. grid, soon surpassing 100,000. Grid interoperability for the millions of distributed energy resources being added on the grid's edge is merely the next logical step in the longstanding trend of modernizing the grid through decentralization.
Interoperability is a tool for unlocking new value across the power system, said Gopstein, and NIST's Framework and Roadmap for Smart Grid Interoperability Standards 4.0 provides strategies for enhancing interoperability and describes the impacts it will have on the grid.
The use of the NIST Gaithersburg campus electrical infrastructure as a smart grid testbed is detailed in NIST's Validation Capabilities of the NIST Campus Power System to Evaluate Distributed Control of Grid-Edge Distributed Energy Resources, published in August 2021.
Technological advances are enabling the possibility of simultaneously and autonomously controlling resources across a widely distributed grid. Such grid control would allow utilities to regulate power and voltage in real-time, thus meeting fast-changing power demands. To do this, utility operators need an understanding of bandwidth, security, integrity, and reliability at the grid’s edge, where renewable energy generators and other distributed resources are often located. Advanced control techniques depend on matching communications capabilities with data flow requirements across the grid.
To address these issues, NIST researchers implemented a 400 megabit per second (Mbps) pipeline for inverter and phasor data from measurement systems installed to monitor the existing 5 megawatt (MW) solar array on its Gaithersburg, Maryland campus. The pipeline captures time-aligned data from multiple sites, enabling researchers to monitor and measure fast occurring events. The testbed also allows for the communication of this information via a variety of communications protocols and wireless network radios. This makes the testbed suitable for testing communication technologies and control strategies in the context of a full-scale distribution circuit.
In July 2021, Connecticut's Public Utilities Regulatory Authority (PURA) established a statewide electric vehicle (EV) program for all classes of customers. To inform baseline standards and protocols for the program, National Association of Regulatory Utility Commissioners (NARUC) ran five workshops in August 2021 and provided technical assistance to Connecticut's PURA. NIST sponsored the workshops through its cooperative agreement funding grant with NARUC.
NARUC's personnel facilitated the workshops, which involved stakeholders from industry, government, regulators, associations, and academia. NIST's Avi Gopstein presented on the importance of grid interoperability, including its potential benefits and strategies for maximizing its impact. NIST's Cuong Nguyen provided a deep dive into the interoperability profile needed for EV managed charging. The profile is being developed in cooperation with industry through a cooperative agreement with Smart Electric Power Alliance (SEPA), which is managing the effort. Nguyen also addressed use cases that have been developed.
In addition to providing technical assistance for these workshops, NIST and NARUC personnel are collecting information and lessons learned from Connecticut's approach. The intent is to produce a case study that will be relevant and helpful to other states pursuing a grid-interoperable EV.
In The Secret Life of Waste Bins, Cities Today reported on how municipalities are using Internet of Things (IoT) to cut costs and provide more efficient services. The report draws from the Global City Teams Challenge (GCTC) guidebook, The Municipal Internet of Things (IoT) Blueprint, which highlights San Leandro, CA and states that its IoT project "is saving US$447,000 a year and seeing energy reductions which are the equivalent of removing over 2,000 metric tons of CO2 annually from the environment."
In 2017, San Leandro constructed one of the first citywide IoT networks, stated the GCTC Blueprint, consisting of over 4,700 LED retrofit streetlights, water control infrastructure for city parks, and city facilities upgrades including HVAC, furnaces, and lighting controls. The IoT network won a Smart 50 Award from the Smart Cities Council in 2018, the Blueprint also said.
Cities Today further reported on the IoT network's development since the 2019 Blueprint's publication. San Leandro leaders realized that the network offered new possibilities that they hadn’t foreseen. A former chief innovation officer for the City of San Leandro, said, “this isn’t just a lighting project. This is our holy grail ... the dashboard that all of our data can be connected to and visualized through.” The network opened up a whole new world of things to be added over time.
The NIST Global City Teams Challenge (GCTC’s) Agriculture and Rural SuperCluster held a workshop at Purdue University, July 21-23, 2021, with participants attending onsite and virtually. The workshop primarily focused on ways to achieve broadband connectivity for agriculture and rural areas. The following summarizes workshop sessions and provides hyperlinks to online videos.
Day 1 Opening Session GCTC ARSC Workshop // Welcome and Introductions: Includes presentations by key workshop stakeholders, with a welcome from NIST’s Michael Dunaway.
Session 1 // Agriculture and Broadband: Examines the significant broadband needs of agriculture and how connectivity will impact agricultural technology and its work force.
Lunch Session // Smart City Challenge and NASA Air Mobility: Addresses the smart city challenge initiative to improve the safety and mobility of West Lafayette, Indiana's residents. Also, addresses NASA's air mobility initiative which seeks to improve agriculture, rural, and urban operations.
Session 2 // Smart Communities, Tribal focus areas, and Funding Priorities: Provides an overview of funding allocated for broadband connectivity for minority communities, including tribal governments. Also shows U.S. Economic Development Administration’s investment priorities related to broadband innovation.
Session 3 // Rural Broadband Connectivity: Discusses public-private partnerships, aiding broadband connectivity for rural areas.
Breakfast Session // WHIN and Indiana Rural Economy: Presents the Wabash Heartland Innovation Network (WHIN) efforts to develop a large-scale, living laboratory for applying Internet of Things to education and scientific research in a ten-county, regional community.
Session 4 // Data Analytics Driving Broadband Mapping: Shows the importance of using the digital divide index for measuring and analyzing digital inclusion; the need for accurate broadband maps; and how data analytics can be applied to broadband infrastructure design.
Session 5 // Innovation & Challenges: States that Broadband connectivity is not enough. What is important is leveraging broadband to improve education, economic development, health care, vital services for rural communities. Such innovation requires active engagement with local leaders.
Session 6 // Smart Regions, ARA Lab and Smart Building: Gives updates on Wireless Living Lab for Smart and Connected Rural Communities; NIST's Smart Regions Collaborative and Blueprint; and the GCTC Smart Building Supercluster.
Session 7 // Trust and Transparency: Shows smart cities and regional initiatives are growing and sustaining economic growth by introducing new technologies that improve the health and well-being of citizens, businesses, and education.
NIST's Ed Griffor gave a tutorial on Cyber-Physical Systems (CPS) and the NIST CPS Framework at the International Joint Conference on Artificial Intelligence, August 20, 2021. CPS and Internet of Things will increasingly use AI, and the tutorial was intended to provide AI researchers with an understanding of:
Griffor then showed the elements of NIST CPS Framework and how they addressed these issues. He also provided additional information on the role of Aspects (high-level groupings of concerns). For example, these include Timing, Data, Trustworthiness, and Human Factors in the Framework's analysis, and their contribution to understanding and organizing CPS technical requirements. Griffor focused on the Trustworthiness Aspect of CPS development, and how it is determined, which is a subject of current interest.
Annually, NIST selects students for Summer Undergraduate Research Fellowships (SURF) to work in areas that support its mission. NIST's intent is to inspire students to serve in these fields. During their 11-week internship, students get exposed to cutting edge research in physical and engineering sciences. NIST researchers also benefit as they get fresh perspectives and thinking in these research areas. Such was the case with the following SURF students who did research on the smart grid and CPS this summer.
Alex Loane, Cornell University, on "Calibration of Smart Grid Simulation Response to Oscillatory Waveforms." Proposed a simulation for testing the responses of hardware on the grid to fluctuations in power, as represented by arbitrary oscillating waveforms. Loane sees such a simulation as being able to isolate multiple problems.
Erik Mitchell, University of Santa Clara, on "Optimizing Energy Consumption in Residential Homes using Reinforcement Learning." Proposed reinforcement learning for home HVACs, allowing them to learn how best to maintain comfort zones. The capability would minimize residential energy costs and collected data would help utilities predict and meet energy demands.
Brian Woo-Shem, University of Santa Clara, on "Occupancy-Based Adaptive Thermostat for Increased Energy Efficiency." This complements Mitchell's research. Instead of today's fixed, set-point thermostats, Woo-Shem recommended adaptive thermostats, which would use predicted times of occupancy for maintaining comfort zones in residences.