5,339 research outputs found
Electric spring and smart load: technology, system-level impact and opportunities
Increasing use of renewable energy sources to combat climate change comes with the challenge of power imbalance and instability issues in emerging power grids. To mitigate power fluctuation arising from the intermittent nature of renewables, electric spring has been proposed as a fast demand-side management technology. Since its original conceptualization in 2011, many versions and variants of electric springs have emerged and industrial evaluations have begun. This paper provides an update of existing electric spring topologies, their associated control methodologies, and studies from the device level to the power system level. Future trends of electric springs in large-scale infrastructures are also addressed
Index to nasa tech briefs, issue number 2
Annotated bibliography on technological innovations in NASA space program
Impact Assessment of Hypothesized Cyberattacks on Interconnected Bulk Power Systems
The first-ever Ukraine cyberattack on power grid has proven its devastation
by hacking into their critical cyber assets. With administrative privileges
accessing substation networks/local control centers, one intelligent way of
coordinated cyberattacks is to execute a series of disruptive switching
executions on multiple substations using compromised supervisory control and
data acquisition (SCADA) systems. These actions can cause significant impacts
to an interconnected power grid. Unlike the previous power blackouts, such
high-impact initiating events can aggravate operating conditions, initiating
instability that may lead to system-wide cascading failure. A systemic
evaluation of "nightmare" scenarios is highly desirable for asset owners to
manage and prioritize the maintenance and investment in protecting their
cyberinfrastructure. This survey paper is a conceptual expansion of real-time
monitoring, anomaly detection, impact analyses, and mitigation (RAIM) framework
that emphasizes on the resulting impacts, both on steady-state and dynamic
aspects of power system stability. Hypothetically, we associate the
combinatorial analyses of steady state on substations/components outages and
dynamics of the sequential switching orders as part of the permutation. The
expanded framework includes (1) critical/noncritical combination verification,
(2) cascade confirmation, and (3) combination re-evaluation. This paper ends
with a discussion of the open issues for metrics and future design pertaining
the impact quantification of cyber-related contingencies
Use of Hooke's law for stabilizing future smart grid - the electric spring concept
Hooke's law for mechanical springs was developed in the 17th century. Recently, new power electronics devices named electric springs have been developed for providing voltage regulation for distribution networks and allowing the load demand to follow power generation. This paper summarizes recent R&D on electric springs and their potential functions for future smart grid. Electric springs can be associated with electric appliances, forming a new generation of smart loads which can adapt according to the availability of power from renewable energy sources. When massively distributed over the power grid, they could provide highly distributed and robust support for the smart grid, similar to the arrays of mechanical springs supporting a mattress. Thus, the 3-century old Hooke's law in fact provides a powerful solution to solving some key Smart Grid problems in the 21st Century. © 2013 IEEE.published_or_final_versio
Droop Control of Distributed Electric Springs for Stabilizing Future Power Grid
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Hardware and Control Implementation of Electric Springs for Stabilizing Future Smart Grid with Intermittent Renewable Energy Sources
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Small Signal Stability Analysis of Distribution Networks with Electric Springs
This paper presents small signal stability analysis of distribution networks with electric springs (ESs) installed at the customer supply points. The focus is on ESs with reactive compensation only. Vector control of ES with reactive compensation is reported for the first time to ensure compatibility with the standard stability models of other components such as the interface inverter of distributed generators (DGs). A linearized state-space model of the distribution network with multiple ESs is developed which is extendible to include inverter-interfaced DGs, energy storage, active loads etc. The impact of distance of an ES from the substation, proximity between adjacent ESs and the R/X ratio of the network on the small signal stability of the system is analyzed and compared against the case with equivalent DG inverters. The collective operation of ESs is validated through simulation study on a standard distribution network
Dynamic performance of transmission pole structures under blasting induced ground vibration
Structural integrity of electric transmission poles is crucial for the reliability of power delivery. In some areas where blasting is used for mining or construction, these structures are endangered if they are located close to blasting sites.
Through field study, numerical simulation and theoretical analysis, this research investigates blast induced ground vibration and its effects on structural performance of the transmission poles. It mainly involves: (1) Blast induced ground motion characterization; (2) Determination of modal behavior of transmission poles; (3) Investigation of dynamic responses of transmission poles under blast induced ground excitations; (4) Establishment of a reasonable blast limit for pole structures; and (5) Development of heath monitoring strategies for the electric transmission structures.
The main technical contributions of this research include: (1) developed site specific spectra of blast induced ground vibration based on field measurement data; (2) studied modal behavior of pole structures systematically; (3) proposed simplified but relatively accurate finite element (FE) models that consider the structure-cable coupling; (4) obtained dynamic responses of transmission pole structures under blast caused ground vibration both by spectrum and time-history analysis; (5) established 2 in/s PPV blast limit for transmission pole structures; (6) developed two NDT techniques for quality control of direct embedment foundations; and (7) described an idea of vibration-based health monitoring strategy for electric transmission structures schematically
Evolutionary Algorithms for Community Detection in Continental-Scale High-Voltage Transmission Grids
Symmetry is a key concept in the study of power systems, not only because the admittance and Jacobian matrices used in power flow analysis are symmetrical, but because some previous studies have shown that in some real-world power grids there are complex symmetries. In order to investigate the topological characteristics of power grids, this paper proposes the use of evolutionary algorithms for community detection using modularity density measures on networks representing supergrids in order to discover densely connected structures. Two evolutionary approaches (generational genetic algorithm, GGA+, and modularity and improved genetic algorithm, MIGA) were applied. The results obtained in two large networks representing supergrids (European grid and North American grid) provide insights on both the structure of the supergrid and the topological differences between different regions. Numerical and graphical results show how these evolutionary approaches clearly outperform to the well-known Louvain modularity method. In particular, the average value of modularity obtained by GGA+ in the European grid was 0.815, while an average of 0.827 was reached in the North American grid. These results outperform those obtained by MIGA and Louvain methods (0.801 and 0.766 in the European grid and 0.813 and 0.798 in the North American grid, respectively)
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