The Smart Grid, regarded as the next generation power grid, uses two-way flows of electricity and information to create a widely distributed automated energy delivery network. In this article, we survey the literature till 2011 on the enabling technologies for the Smart Grid. We explore three major systems, namely the smart infrastructure system, the smart management system, and the smart protection system. We also propose possible future directions in each system. colorred{Specifically, for the smart infrastructure system, we explore the smart energy subsystem, the smart information subsystem, and the smart communication subsystem.} For the smart management system, we explore various management objectives, such as improving energy efficiency, profiling demand, maximizing utility, reducing cost, and controlling emission. We also explore various management methods to achieve these objectives. For the smart protection system, we explore various failure protection mechanisms which improve the reliability of the Smart Grid, and explore the security and privacy issues in the Smart Grid.

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Smart Grid — The New and Improved Power Grid: A Survey

The increasing interest in integrating intermittent renewable energy sources into microgrids presents major challenges from the viewpoints of reliable operation and control. In this paper, the major issues and challenges in microgrid control are discussed, and a review of state-of-the-art control strategies and trends is presented; a general overview of the main control principles (e.g., droop control, model predictive control, multi-agent systems) is also included. The paper classifies microgrid control strategies into three levels: primary, secondary, and tertiary, where primary and secondary levels are associated with the operation of the microgrid itself, and tertiary level pertains to the coordinated operation of the microgrid and the host grid. Each control level is discussed in detail in view of the relevant existing technical literature.

Trends in Microgrid Control

Smart Grid - The New and Improved Power Grid:

Simulation and the monte carlo method

A communication infrastructure is an essential part to the success of the emerging smart grid. A scalable and pervasive communication infrastructure is crucial in both construction and operation of a smart grid. In this paper, we present the background and motivation of communication infrastructures in smart grid systems. We also summarize major requirements that smart grid communications must meet. From the experience of several industrial trials on smart grid with communication infrastructures, we expect that the traditional carbon fuel based power plants can cooperate with emerging distributed renewable energy such as wind, solar, etc, to reduce the carbon fuel consumption and consequent green house gas such as carbon dioxide emission. The consumers can minimize their expense on energy by adjusting their intelligent home appliance operations to avoid the peak hours and utilize the renewable energy instead. We further explore the challenges for a communication infrastructure as the part of a complex smart grid system. Since a smart grid system might have over millions of consumers and devices, the demand of its reliability and security is extremely critical. Through a communication infrastructure, a smart grid can improve power reliability and quality to eliminate electricity blackout. Security is a challenging issue since the on-going smart grid systems facing increasing vulnerabilities as more and more automation, remote monitoring/controlling and supervision entities are interconnected.

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1315&context=electricalengineeringfacpub

A Survey on Smart Grid CommunicationInfrastructures: Motivations, Requirements andChallenges

A comprehensive study on the effect of a lossy ground on the induced voltages on overhead power lines by a nearby lightning strike is presented The ground conductivity plays a role in both the evaluation of the lightning radiated fields and of the line parameters To be calculated by means of a rigorous theory, both fields and line constants need important computation time, which, for the problem of interest, is still prohibitive The aim of this paper is to discuss and analyze the various simplified approaches and techniques that have been proposed for the calculation of the fields and the line constants when the ground cannot be assumed as a perfectly conducting plane Regarding the radiated electromagnetic field, it is shown that the horizontal electric field, the component which is most affected by the ground finite conductivity, can be calculated in an accurate way using the Cooray-Rubinstein simplified formula The presence of an imperfectly conducting ground is included in the coupling equations by means of two additional terms: the longitudinal ground impedance and the transverse ground admittance, which are both frequency-dependent The latter can generally be neglected for typical overhead lines, due to its small contribution to the overall transverse admittance of the line Regarding the ground impedance, a comparison between several simplified expressions used in the literature is presented and the validity limits of these expressions are established It is also shown that for typical overhead lines the wire impedance can be neglected as regard to the ground impedance

Influence of a lossy ground on lightning-induced voltages on overhead lines

A modeling procedure that permits calculation of lightning-induced voltages on overhead lines starting from the channel-base current is discussed. The procedure makes use of a coupling model already presented in the literature, based on transmission line theory, for field-to-overhead line coupling calculations. Both models are discussed and compared with experimental results. The hypothesis of perfect conducting ground, used to analyze the voltages induced on an overhead line by a nearby lightning return stroke with a striking point equidistant from the line terminations, and the limits of its validity are determined. A comparison shows that peak value and maximum front steepness of the induced voltages calculated using other lightning return-stroke models differ. It is also shown that another coupling model used in the power-lightning literature by several other authors may result in a less accurate estimation of the induced voltages. >

Lightning-induced voltages on overhead lines

Compares five lightning return stroke current models that exhibit a simple relationship between the current at the return stroke channel-base and the current along the return stroke channel, namely the Bruce-Golde (BG) model, the transmission line (TL) model, the Master, Uman, Lin, and Standler (MULS) model, the Traveling Current Source (TCS) model, and the Modified Transmission Line (MTL) model, by assuming a common current wave shape at the channel base and then calculating the channel currents and charges and the resultant electric and magnetic fields. Two characteristics distinguish the models: the treatment of the return stroke wave front, and the spatial and temporal distribution of charge removed from the leader channel. The TL model is unrealistic for long-time field calculations owing to the fact that no net charge is removed from the channel. The other four models produce overall fields which are reasonable approximations to measured fields from natural lightning

Lightning return stroke current models with specified channel‐base current: A review and comparison

On lightning return stroke models for LEMP calculations

An analysis of electric and magnetic fields radiated by lightning first and subsequent return strokes to tall towers is presented. The contributions of the various components of the fields, namely, static, induction, and radiation for the electric field, and induction and radiation for the magnetic field are illustrated and discussed. It is shown in particular that the presence of a tower tends, in general, to increase substantially the electric and magnetic field peaks and their derivatives. This increase is mainly caused by the presence of two oppositely propagating current wavefronts originating from the tower top and by the very high propagation velocity of current pulses within the tower, and depends essentially on the wavefront steepness of the channel-base current. Because of the last factor, the increase of the field magnitudes is found to be significantly higher for subsequent return strokes, which are characterized by much faster risetimes compared to first return strokes. The presented results are consistent with experimental observations of current in lightning strokes to the Toronto CN Tower and of the associated electric and magnetic fields measured 2 km away. These findings partially explain the fact that subsequent return strokes characterized by lower current peaks but higher front steepnesses and return stroke speeds may result in higher field peaks. The results obtained have important implications in electromagnetic (EM) compatibility. It is found that lightning strokes to tall metallic objects lead to increased EM field disturbances. Also, subsequent return strokes are to be considered an even more important source of EM interference than first return strokes. Indeed, EM fields from subsequent strokes are characterized by faster fronts and additionally, they may reach greater peaks than first strokes. Lastly, findings of this study emphasize the difficulty of extracting reliable lightning return stroke current information from remote EM field measurements using oversimplified formulae.

Carlo Alberto Nucci

Papers

Influence of a lossy ground on lightning-induced voltages on overhead lines

Lightning-induced voltages on overhead lines

Lightning return stroke current models with specified channel‐base current: A review and comparison

On lightning return stroke models for LEMP calculations

Current and electromagnetic field associated with lightning-return strokes to tall towers