Plug-in vehicles can behave either as loads or as a distributed energy and power resource in a concept known as vehicle-to-grid (V2G) connection. This paper reviews the current status and implementation impact of V2G/grid-to-vehicle (G2V) technologies on distributed systems, requirements, benefits, challenges, and strategies for V2G interfaces of both individual vehicles and fleets. The V2G concept can improve the performance of the electricity grid in areas such as efficiency, stability, and reliability. A V2G-capable vehicle offers reactive power support, active power regulation, tracking of variable renewable energy sources, load balancing, and current harmonic filtering. These technologies can enable ancillary services, such as voltage and frequency control and spinning reserve. Costs of V2G include battery degradation, the need for intensive communication between the vehicles and the grid, effects on grid distribution equipment, infrastructure changes, and social, political, cultural, and technical obstacles. Although V2G operation can reduce the lifetime of vehicle batteries, it is projected to become economical for vehicle owners and grid operators. Components and unidirectional/bidirectional power flow technologies of V2G systems, individual and aggregated structures, and charging/recharging frequency and strategies (uncoordinated/coordinated smart) are addressed. Three elements are required for successful V2G operation: power connection to the grid, control and communication between vehicles and the grid operator, and on-board/off-board intelligent metering. Success of the V2G concept depends on standardization of requirements and infrastructure decisions, battery technology, and efficient and smart scheduling of limited fast-charge infrastructure. A charging/discharging infrastructure must be deployed. Economic benefits of V2G technologies depend on vehicle aggregation and charging/recharging frequency and strategies. The benefits will receive increased attention from grid operators and vehicle owners in the future.

Review of the Impact of Vehicle-to-Grid Technologies on Distribution Systems and Utility Interfaces

In a world where resources are scarce and urban areas consume the vast majority of these resources, it is vital to make cities greener and more sustainable. Advanced systems to improve and automate processes within a city will play a leading role in smart cities. From smart design of buildings, which capture rain water for later use, to intelligent control systems, which can monitor infrastructures autonomously, the possible improvements enabled by sensing technologies are immense. Ubiquitous sensing poses numerous challenges, which are of a technological or social nature. This paper presents an overview of the state of the art with regards to sensing in smart cities. Topics include sensing applications in smart cities, sensing platforms and technical challenges associated with these technologies. In an effort to provide a holistic view of how sensing technologies play a role in smart cities, a range of applications and technical challenges associated with these applications are discussed. As some of these applications and technologies belong to different disciplines, the material presented in this paper attempts to bridge these to provide a broad overview, which can be of help to researchers and developers in understanding how advanced sensing can play a role in smart cities.

The Role of Advanced Sensing in Smart Cities

A building manager includes a communications interface configured to receive information from a smart energy grid. The building manager further includes an integrated control layer configured to receive inputs from and to provide outputs to a plurality of building subsystems. The integrated control layer includes a plurality of control algorithm modules configured to process the inputs and to determine the outputs. The building manager further includes a fault detection and diagnostics layer configured to use statistical analysis on the inputs received from the integrated control layer to detect and diagnose faults. The building manager yet further includes a demand response layer configured to process the information received from the smart energy grid to determine adjustments to the plurality of control algorithms of the integrated control layer.

Smart building manager

Integrating the various embedded devices and systems in our environment enables an Internet of Things (IoT) for a smart city. The IoT will generate tremendous amount of data that can be leveraged for safety, efficiency, and infotainment applications and services for city residents. The management of this voluminous data through its lifecycle is fundamental to the realization of smart cities. Therefore, in contrast to existing surveys on smart cities we provide a data-centric perspective, describing the fundamental data management techniques employed to ensure consistency, interoperability, granularity, and reusability of the data generated by the underlying IoT for smart cities. Essentially, the data lifecycle in a smart city is dependent on tightly coupled data management with cross-cutting layers of data security and privacy, and supporting infrastructure. Therefore, we further identify techniques employed for data security and privacy, and discuss the networking and computing technologies that enable smart cities. We highlight the achievements in realizing various aspects of smart cities, present the lessons learned, and identify limitations and research challenges.

Smart Cities: A Survey on Data Management, Security, and Enabling Technologies

Systems and methods for building automation system management are shown and described. The systems and methods relate to fault detection via abnormal energy monitoring and detection. The systems and methods also relate to control and fault detection methods for chillers. The systems and methods further relate to graphical user interfaces for use with fault detection features of a building automation system.

Automated fault detection and diagnostics in a building management system

In this paper, we review the emerging challenges and research opportunities for voltage control in smart grids. For transmission grids, the voltage control for accommodating wind and solar power, fault-induced delayed voltage recovery, and measurement-based Thevenin equivalent for voltage stability analysis are reviewed. For distribution grids, the impact of high penetration of distributed energy resources is analyzed, typical control strategies are reviewed, and the challenges for local inverter Volt–Var control is discussed. In addition, the motivation, state-of-the-art, and future directions of the coordination of transmission system operators (TSO) and distribution system operators (DSO) are also thoroughly discussed.

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Review of Challenges and Research Opportunities for Voltage Control in Smart Grids

This paper explores the existing energy harvesting technologies, their stage of maturity and their feasibility for powering sensor nodes. It contains a study of the energy requirements of the sensor nodes that are a part of the commercial domain. Further, it investigates methods and concepts for harvesting the energy from electric and magnetic fields present near utility assets through laboratory experimentation. The flux concentrator based approach that scavenges the magnetic field was considered to be the most promising solution providing nearly 250mW of power sufficient to power a sensor node.

A scoping study of electric and magnetic field energy harvesting for wireless sensor networks in power system applications

Rapid increase in electric power demand, introduction of RPS mandates, and a push towards electrification in the transportation sector is expected to increase power system stresses and disturbances. To tackle these power system issues and maintain high system reliability, it is essential to have information about the condition of assets present on the grid. Presently, due to the absence of low cost flexible grid wide monitoring solutions, complete information of the system is not achievable. This paper deals with the development of a new class of sensors called the smart “stick-on” sensors. These are low cost, self-powered, universal sensors that provide a flexible monitoring solution for grid assets. These sensors can be mass deployed due to low cost, need low maintenance as they are self-powered, and can be used for monitoring a variety of grid assets. This paper also presents the details on the network architecture, interoperability and integration, and different design aspects of the stick-on sensor, such as novel energy harvesting techniques, power management, wide operating range, and reliability. It is envisioned that the smart stick-on sensors shall be an enabling technology for monitoring a variety of grid assets and prove to be an essential element of the Smart Grid.

Smart “Stick-on” Sensors for the Smart Grid

Voltage sensing of the utility network provide critical information for asset management, prioritizing asset replacements, increasing situational awareness and providing increased visibility of the grid. For ease of use, and to increase commercial appeal among utilities, these sensors should be designed to have a low cost, long life ( $> {10}~{\hbox {years}}$ ), be self-powered, and require no maintenance. This paper deals with the development of a novel low-cost wireless voltage sensor for medium- and high-voltage (MV/HV) utility assets such as cables, transformers, switchgear, capacitor banks, and conductors. A review of existing techniques along with their drawbacks is outlined in this paper. Further, the challenges pertaining to the development a low-cost floating voltage sensor such as variability of voltage, self-calibration requirements, and distance-to-earth variations are presented. These challenges are circumvented by deriving a detailed mathematical model of the sensor. Further, using a set of valid assumptions, a new moving average voltage sensing (MAVS) algorithm is proposed, tested using simulations and validated using a high-voltage prototype. The wireless voltage sensor prototype is tested at up to 35 kV and is built to accommodate electric field energy harvesting in addition to voltage sensing. The prototype has a low-volume production cost of $150 and shows promising results by providing self-calibrated measurements capable of tracking the voltage variation with less than 2.5% error.

A Low-Cost Wireless Voltage Sensor for Monitoring MV/HV Utility Assets

Utilities implementing diverse grid modernization initiatives are observing greater volatility at the grid edge that cannot be managed using traditional electromechanically switched centralized command and control solutions. The decentralized, distributed, and dynamic capabilities required can only be achieved with semiconductor-based power electronics solutions that are deployed appropriately along the grid edge. The key control objective is the fast and granular control of volts and vars at hundreds of points along the feeder, a functionality typically associated with static synchronous compensators (STATCOMs) and unified power flow controllers (UPFCs), albeit in a distributed manner and at lower voltage levels. Several companies are now offering grid-edge power-electronics solutions to solve this new set of challenges, with substantial data from the field validating the benefits that such solutions can provide. This article discusses the challenges, solutions, and some of the results that point to the benefits that power electronics at the grid edge can provide for utilities.

Rohit Moghe

Papers

Review of Challenges and Research Opportunities for Voltage Control in Smart Grids

A scoping study of electric and magnetic field energy harvesting for wireless sensor networks in power system applications

Smart “Stick-on” Sensors for the Smart Grid

A Low-Cost Wireless Voltage Sensor for Monitoring MV/HV Utility Assets

Power Electronics at the Grid Edge : The key to unlocking value from the smart grid