- Carlson, Erica; Spatial Complexity Due to Bulk Electronic Liquid Crystals in Superconducting Dy-Bi2212
Authors: Authors: B. Phillabaum (Purdue), E. W. Carlson (Purdue), K. A. Dahmen (U. Illinois)
Surface probes such as scanning tunneling microscopy (STM) have detected complex electronic patterns at the nanoscale in many high temperature superconductors. In cuprates, the pattern formation is associated with the pseudogap phase, a precursor to the high temperature superconducting state. However, the fundamental physics governing the pattern of the locally oriented charge modulations has not yet been identified. Using new methods we have developed for decoding these surface structures, we find that the locally oriented domains indeed persists throughout the bulk of the material. We furthermore find that the intricate pattern formation is set by a delicate balance between disorder, interactions, and material anisotropy, leading to a fractal nature of the cluster pattern. The methods we have developed can be extended to many other surface probes and materials, enabling surface probes to determine whether surface structures are confined only to the surface, or whether they extend throughout the material.
- C.M., Liyanagedera; Configure Electronic Interfaces for third party hardware control and monitoring in AMI
Authors: Liyanagedera C.M. and Prof. N. Athula Kulatunga
The worldwide demand for Advanced Meter Infrastructure is growing. Smart Meter manufactures and electric utilities have to rely on third party developers to realize the promised potentials of Smart Grid. Smart Meters come with wireless communication capabilities and they are manufactured according to international standards. Third party application developers must understand the details of meter interval data storage formats and used wireless communication technologies before integrating Smart Meters into localized controllers for peak shaving applications. This poster outlines how to develop interface hardware using minimum understanding of AMI to utilize existing and future appliances and other electrical apparatus in HANs and other DSM schemes.
- Debnath, Suman; Next Generation of Reliable and Efficient Large-Scale Wind Energy Conversion Systems
Authors: Mr. Suman Debnath, Dr. Maryam Saeedifard
The growing demand for wind power generation has pushed the capacity of wind turbines towards MW power levels. Higher capacity of the wind turbines necessitates operation of the generators and power electronic conversion systems at higher voltage/power levels. The power electronic conversion system of a wind energy conversion system (WECS) needs to meet the stringent requirements in terms of reliability, efficiency, scalability and ease of maintenance, power quality, and dv/dt stress on the generator/transformer. Although the multilevel converters including the neutral point clamped (NPC) converter and the active NPC converter meet most of the requirements, they fall short in reliability and scalability. Motivated by modularity/scalability feature of the modular multilevel converter (MMC), this poster presents the results of ongoing research on the control and performance improvement of the MMC and MMC-derived hybrid topologies for the WECSs.
- Fan, Jiyuan
- Glover, Steve; Abstract:Networked Secure Scalable Microgrids (SSMTM) for High Penetration of Renewable Energy
As part of Sandia’s Laboratory Directed Research and Development (LDRD) program, in which projects that address National needs through high-risk research are selected competitively, Sandia has recently initiated a project dealing with secure scalable microgrid architectures. This particular project is a Grand Challenge LDRD spanning several fields of expertise including: informatics and agents for high-level control and reasoning; Hamiltonian based nonlinear distributed controls for improved analysis and performance; hardware, modeling, and simulation to support the design and analysis development; communication theory to understand performance and potential tradeoff spaces; and cyber security to address potential vulnerabilities of power systems in the future.
To broaden Sandia’s project resources in terms of experience, skills, and spreading the workload, Sandia has recently partnered with Purdue University and PC Krause and Associates (PCKA), a company located in the Purdue Research Park, who collectively have extensive experience in the modeling, simulation, and analysis of power-electronic-based systems used in military ships, aircraft, spacecraft, and terrestrial vehicles. Several faculty and students from the School of Electrical Engineering and researchers at PCKA are working closely with Sandia, developing and validating computer models of the diverse collection of sources and loads that comprise a typical microgrid. The results of this collaboration were recently featured in several special sessions of the IEEE CYBER 2012 Conference in Thailand.
- Halappanavar, Mahantesh; Towards Graph-theoretic Approaches for Modeling of Electric Power Grids and Model Reduction
Authors: Halappanavar, Mahantesh and Emilie Hogan: Pacific Northwest National Laboratory
Combinatorial approaches have become prominent in solving many challenging problems in science and engineering. In the context of complex energy systems being studied under the DOE-ASCR M2ACS project (Multifaceted Mathematics for Complex Energy Systems), we will present two problems and our preliminary work on graph-theoretic approaches in solving them. The first problem is accurate characterization of the topological and electrical structure of electric power grids, and the second problem is model reduction for computational feasibility.
Graph-theoretic approaches have long been used for characterizing the topological structure of power grids. The central idea of such approaches is to use known algorithms for generating random graphs and then using graph-based metrics to match the characteristics with those from real-world power grid models, such as Western Interconnect and Eastern Interconnect. Popular random graph algorithms used for this purpose are Erdős-Rényi, preferential attachment, random geometric graph, and several variants of these basic algorithms. However, as is evident from our work, as well as the work of several others, none of these standard graph algorithms generate topologies that match known models accurately. Several graph-based metrics such as degree distribution, clustering coefficient, diameter, and average shortest path length can be used to quantitatively express this mismatch. An additional challenge is to model the electrical properties of a grid expressed as a function of the amount of power flowing through different buses (vertices) and branches (edges).
In our preliminary work, we are exploring several variants of the random geometric graph algorithm for the purposes of generating synthetic models of the power grid. For validation, we are also exploring different metrics that have not been used previously. One such metric is graphlet degree distribution that enumerates the number of different subgraph patterns that a vertex is part of; standard degree distribution is an instance where the subgraph is a single edge. In addition, we have identified a key shortcoming in all the previous work due to inaccurate representation of power grids. Specifically, power grids are heterogeneous in nature, but the random graph based models tend to be homogenous. By exploiting this fact, we have developed a network-of-networks model for power grids and are currently quantifying standard metrics for real world models using this approach. Preliminary results on the emergence of hierarchical network-of-networks structure will be presented.
The second problem that we are investigating involves model reduction. Given that phasor measurement devices (PMUs) are increasingly being deployed, large-scale analysis of time-series data from these measurements will become computationally intensive. By reducing the number of measurements that need to be tracked, model reduction will enable timely analysis of large-scale data. In particular, by grouping power generators that behave similarly, transient phenomena from electrical disturbances can be studied efficiently. Graph-theoretic approaches can be used to group (cluster) generators that behave similarly. Intuitively, the idea is to build a nearest neighbor graph based on quantitative similarities between time-series phasor measurements. This graph provides a low-dimensional approximation to inherently high-dimensional data. Contingency analysis is another application that benefits from clustering and is being explored through this project.
- Jin, Kevin; Modeling Methodologies for Power Grid Control System Evaluation
Authors: David Nicol, Kevin Jin, Huaiyu Zhu, Electrical and Computer Engineering Yuhao Zheng, Lenhard Winterrowd, Computer Science All authors are from University of Illinois at Urbana-Champaign.
A high ﬁdelity testbed for large-scale system analysis and evaluation requires emulation to represent the execution of critical software, and simulation to model an extensive ensemble of background computation and communication. We leverage our prior work showing that large numbers of virtual environments may be emulated on a single host, and that the timestamped interactions between them can be mapped to virtual time, and we leverage our existing work on simulation of large-scale communication networks. This work brings these concepts together, marrying the scale emulation framework OpenVZ (modiﬁed earlier to operate in virtual time) with a scalable network simulator S3F. Our algorithmic contributions lay in the design and management of virtual time as it transitions from emulation, to simulation, and back. In particular, inescapable uncertainties in emulation behavior force us to explicitly set and reset timestamps so as to avoid either emulator or simulator having to deal with a packet arriving in its logical past. We provide analytic bounds and empirical evidence that the error introduced in resetting timestamps is small.
The high-fidelity, highly scalable simulation/emulation platform is primarily used for security evaluation in power grid control networks. The testbed is capable to create models that support security assessment in a realistic large-scale setting. In this work, we present a case-study using this capability, of a cyber-attack with the smart power grid communication infrastructure. We plan to utilize the testbed for creating a backbone at the core of the Smart Grid testbed at Illinois that connects various real/virtual smart grid components.
- Kuruppu, S.; Smart Meter based Non-Intrusive appliance detection algorithm for local real-time feedback process
Authors: S. Kuruppu and Prof. N. Athula Kulatunga
Smart meters and related technologies are becoming a noteworthy aspect of residential electrical power systems as proper energy feedback can result in significant energy savings. Smart meters also facilitate implementation of "time of use" (TOU) pricing for the residential sector. Results of Advanced Meter Infrastructure (AMI) pilot studies reveal that it is possible to save 12-15 % of energy saving and maximum demand shifting to low peak time when appliance specific disintegrated real-time energy feedback is provided to consumers or controllers. With current technology, appliance level detection requires costly hardware installation and is quite impossible to deploy in large scale AMIs. It would be much more cost effective to predict appliance level consumption using smart meters already installed in premises. However, smart meter has only one current transducer per phase, rendering appliance usage detection challenging. This poster proposes an algorithm which can be performed on the data collected by the smart meter and a real-world example of its application.
- Lee, Hyemi; Translating theory to practice: Understanding the evaluative structure of consumer attitudes towards green technologies
Authors: Hyemi Lee (graduate student presenter) & Meghan E. Norris, PhD
Social psychologists know that it is not a matter of if attitudes can predict behavioral outcomes, but when. The when is dependent on considerations of underlying strength-related attitude attributes. Despite this, there has been very little application of the attitude-strength literature to the field of smart grid technology. This is surprising: consumers are displaying powerful resistance to smart grid initiatives, in some cases resulting in legal action (e.g., BCHRT 300: Citizens for Safe Technology Society obo others v. B.C. Hydro 2012). Such resistance highlights a need for researchers to better understand the underlying attributes of consumer smart grid attitudes to promote effective communication between researchers and consumers that could lead to attitude and behavior change. The intention of this research is not necessarily to encourage consumer adoption of smart grid, but rather to promote effective communication that empowers consumers to make confident and informed choices. Related to the current project, past work demonstrated that providing an affective/cognitive match between persuasive (attitude change) appeals and attitudinal-bases leads to greater attitude change than a mismatch (Fabrgiar & Petty, 1999). Thus, this study measured the degree to which attitudes towards green technologies are affectively or cognitively based. Data showed that for all smart energy topics studied, attitudes tend to be more cognitively held than affectively. This pattern did not hold for the issue of political action which has previously been linked to endorsement of green technologies. Information available to consumers on smart grid initiatives will be discussed in light of its likely ability to change attitudes and behavior based on these findings.
- Loetscher, R.; Smart Meter Based Tools to Enhance Feedback Oriented DSM with Time of Use Rates
Authors: R. Loetscher, S. Kuruppu and Prof. N. Athula Kulatunga
Time of day electric utility rates (TOU) are unavoidable. Consumers have no idea how TOU rates will impact their energy bills. Studies have shown that TOU accompanies by real-time feedback help reducing energy consumption and shifting loads to off-peak hours. Soon, smart meters with wireless communication capabilities will be in every household. Using the capabilities of smart meters, detailed usage of appliances can be provided to consumers via web applications. By allowing consumers to apply and test the impact of different rates, effectiveness of feedback based DSM can be enhances. Features and capabilities of web application are presented with a real world example.
- Navaratne, Uditha Sudheera; Hybrid Testbead for Advanced Metering Infrastructure (AMI) Emulation for Smart Meter Base Product Design and Testing
Authors: Navaratne, U.S. and Prof. N. Athula Kulatunga
AMI consists of large number of smart meters, concentrators having metering and communication functionalities with central or distributed control and monitoring system. Most simulators available in today facilitate either one of wireless network simulation or power system simulation in one package. Fact that AMI emulation needs both wireless network and power system simulation in addition to meter functionality emulation, makes it hard for develop a simulation environment to simulate the true essence of the AMI network. Software plus hardware base test bed provide vast functionality and testing support with true essence of the behavior of wireless network. This poster demonstrate the work done in order to develop hardware in loop testbed for AMI emulation.
- Pomalaza-Raez, Carlos; Sustainable Electric Power Grids – A Transdisciplinary Challenge
Authors: Pedro Nardelli (Graduate (PhD) student at the University of Oulu, Finland), Carlos Pomalaza-Ráez (Purdue University, USA), Matti Latva-aho (University of Oulu, Finland)
The architecture of modern power grids tends to become more distributed in terms of both generation and consumption. In addition to the traditional energy sources, a modern power grid will also have a good amount of renewable sources, e.g. wind power, solar, each with its own spatial, temporal characteristics. Furthermore, there is the presence of a pervasive two way communications readily available for the monitoring and control of the grid. In order to ensure that such grid is sustainable, i.e. maintainable at certain level for a large period of time, its modeling and analysis should take into account not only the technological aspects but equally important the underlying social, economical, cultural and environmental scenarios where the grid is supposed to operate. Our proposal is to build such model using multi-agent systems and cellular automata paradigms, assessing the dynamics of the smart grid system in time and space.
- Qin, Jiangchao; Performance Improvement of Modular Multilevel Converters (MMCs) for HVDC Transmission Systems
Authors: Jiangchao Qin and Maryam Saeedifard
The voltage-sourced converter (VSC) based high-voltage direct-current (HVDC) transmission technology is one of the most promising technologies for (i) expansion of the power networks for large cities and in-feeding the city centers, (ii) grid integration of renewable energy resources, i.e., hydropower, wind farms, and solar plants, (iii) long-distance bulk-power transmission, (iv) interconnection of asynchronous power grids, and (v) electrification of isolated power loads, islands, and oil and gas stations. The key enabling components for the VSC-HVDC systems are the development of highly efficient, reliable, and scalable high-power VSCs and sophisticated control and protection strategies.
The recently introduced modular multilevel converter (MMC) is the most promising topology due to its modularity and scalability. However, there are a few technical challenges associated with the control and operation of the MMC-HVDC system including (i) balancing the SM capacitor voltages at their desired values without creating unnecessary SM switching transitions and sacrificing the efficiency, (ii) reducing the circulating currents flowing through the three phases of the MMC. Although the circulating currents have no effect on the ac side of the MMC, if not properly eliminated/minimized, then increase the amplitude of the SM capacitor voltage ripples, rating values of the converter components, and converter losses, (iii) handling the dc-side short circuit faults. In MMC-HVDC systems, in case of a fault occurrence on the dc side, the switching devices are blocked. However, the diodes provide a current path for the fault current from ac to dc sides until the ac circuit breakers open. Therefore, the MMC by itself does not provide dc-fault-handling capability.
This poster presents the proposed method and results of our ongoing research which has been focused on addressing the aforementioned challenges associated with MMC-HVDC systems.
- Rashkin, Lee; Controlling for Large-Displacement Stability in AC Microgrids
In any ac power system, it is important to regulate the amplitude and frequency of voltages throughout the system. Historically, this has been accomplished by ensuring sufficient spinning reserve, using droop-compensated speed/frequency governors, and controlling the average frequency through the scheduling of dispatchable generators. Control strategies for emerging microgrids are being patterned after the classic grid. However, there are major differences between the classic grid and a typical microgrid. In the classic grid, all generators have similar and well-known dynamic characteristics since there are only a small number of manufacturers world-wide and since the technology is similar between manufacturers (e.g. wound-field synchronous machines). On the other hand, in a typical microgrid, there are numerous power sources with diverse characteristics (photovoltaic arrays, wind turbines, diesel-engine-driven generators), approaches of power conversion (converter and inverter circuits), and associated control strategies, leading to a wide range of dynamic characteristics among the constituent components. Mindful of these differences, it is desirable to develop control methodologies that will ensure stability following disturbances both large and small. A new control paradigm is set forth based upon a centralized clock for synchronizing all components within the microgrid. Computer studies illustrate the feasibility of the proposed approach and establish an inverter design that ensures large-disturbance stability.
- Rezkin, Leon; Data quality evaluation and assurance framework for SCADA systems.
Authors: Leon Reznik and Elisa Bertino
The poster presents the design of the data quality (DQ) evaluation and assurance framework for SCADA and sensor networks energy industry applications. The design aims at developing a comprehensive DQ evaluation and assurance methodology and tools focusing on an integration of various factors affecting DQ in SCADA systems including accuracy, reliability, timeliness, security, and safety into a single methodological and technological framework. By presenting to an end user or an application the DQ indicators, the framework will significantly increase thetrustworthiness of the SCADA systems and the confidence, with which users apply them in an energy system control. It will transform the ways of interacting by giving, for the first time, a user an opportunity to understand and compare various data files, streams and sources based on the associated DQ with integral quality characteristics incorporating various aspects of a system functionality and integrating both computational and physical components.
The framework includes generic data structures and algorithms covering DQ evaluation and assurance for a wide range of data sources typical in power industry. Its operation is based on incorporating data and process provenance schemes along with the methods evaluating data and system accuracy, reliability and trustworthiness.
- Seo, Seung-Hyun; Encryption Key Management for Secure Communication in Smart Advanced Metering Infrastructures.
Authors: Authors: Seung-Hyun Seo, Xiaoyu Ding and Elisa Bertino
Smart grid technology can improve environmental sustainability and increase the efficiency of energy management. Because of these important benefits, conventional power grid systems are being replaced with new, advanced smart grid systems utilizing Advanced Metering Infrastructures (AMIs). These smart grid systems rely on current information and communication technology (ICT) to provide enhanced services to both users and utility companies. However, the increased use of ICT makes smart grid systems vulnerable to cyber-attacks, such as spoofing, eavesdropping and man-in-the-middle attacks. A major security concern is related to secure data transmission between the smart meters and the utility. Encryption techniques are typically used for such purpose. However the deployment of encryption techniques in an AMI requires efficient and scalable approaches for managing encryption keys. In this paper, we propose an efficient encryption key management mechanism for end-to-end security in the AMI. By applying certificateless public key cryptography for smart meter key management, our approach eliminates certificate management overhead at the utility. Moreover, our mechanism is practical, because it does not require any extra hardware for authentication of the smart meters.
Authors: Bilal Shebaro, Daniele Midi, Elisa Bertino
Packet losses in a wireless sensor network represent an indicator of possible attacks to the network. Detecting and reacting to such losses is thus an important component of any comprehensive security solution. However, in order to quickly and automatically react to such a loss, it is important to determine the actual cause of the loss. In a wireless sensor networks, packet losses can result from attacks affecting the nodes or the wireless links connecting the nodes. Failure to identify the actual attack can undermine the efficacy of the attack responses. We thus need approaches to correctly identify the cause of packet losses. In this paper, we address this problem by proposing and building a fine-grained analysis (FGA) tool that investigates the causes of packet losses and reports the most likely cause of these losses. Our tool uses parameters, e.g. RSSI and LQI, transmitted with every received packet to profile the links between nodes and their corresponding neighborhood. Through real-world experiments, we have validated our approach and shown that our tool is able to differentiate between the various attacks that may affect the nodes and the links.
- Straub, Arik; UHF Antenna Design, Simulation, Implementation for HVAC Systems
Author: A. Straub, C. Pomalaza-Ráez, A. Eroglu (all Indiana University – Purdue University Fort Wayne, Fort Wayne, IN)
Remote control and monitoring of heating, ventilation, and air conditioning (HVAC) systems carries great importance for manufacturers due to several factors including energy efficiency, cost, maintenance, reliability and on time service. In this paper, the design, simulation, implementation, and measurement of planar antennas that can be interfaced with electric machine at ultra-high frequency (UHF) range for monitoring and control of HVAC system wirelessly are presented. Three different ultra-high frequency antennas are designed, simulated, implemented, and tested for use with a motor in a heating, ventilation and air conditioning (HVAC) system. Basic antenna layouts, number of vias, and double-sided or single-sided PCB layouts are considered. The designs were modeled using the 3-D electromagnetic simulator Ansoft HFSS. After the simulation, a series of wireless communication boards were implemented in a real HVAC system. Vector network analyzer (VNA) measurements were taken and link quality indicator (LQI) tests were conducted. Overall, the measurements from the VNA match closely to the simulation results from HFSS, and the range and link quality measurements give a baseline for future antenna design.
- Taha, Ahmad; Decision Making in Smart-Grids Supporting Renewable Energy Standards: A Bi-Level Multi-Period Formulation.
Authors: Ahmad Taha, PhD student, School of Electrical and Computer Eng'g, Purdue University
Dr. Jitesh Panchal, Assistant Professor, School of Mechanical Eng'g, Purdue University.
A bi-level multi-period decision making formulation is presented for deregulated smart-grids that integrates renewable energy generation considering Independent System Operators'~(ISO) and Generation Companies'~(GENCOs) objectives. The upper-level problem corresponds to the ISOs, whereas the lower-level decisions are made by GENCOs. We consider that some GENCOs are green energy producers (GEPs), while others are black energy producers (BEPs). ISOs incentivize GEPs to generate energy through the payment of time-varying subsidy price. The ISO's main objective is to maximize an overall system welfare (OSW) that includes factors such as: consumer surplus, energy cost, renewable energy subsidy price, and environmental standards. The lower-level problem corresponding to the GENCOs is based on maximizing the players' profits. The integrated problem solves for optimal time-varying subsidy price and equilibrium energy quantities. The formulation enables the integration of policies, such as Feed-In-Tariff policy, to accelerate the investment in renewable energy.
- Wang, Mu; New Automatic Differentiation Algorithms for Hessian Computation
Author: Mu Wang, Assefaw Gebremedhin and Alex Pothen
Automatic Differentiation (AD) is a set of techniques for analytically evaluating the derivatives of a function specified by a computer program. A basic underlying concept used by AD algorithms is the
computational graph of a function, a directed acyclic graph (DAG) where vertices represent variables and edges represent data dependencies. Such a DAG is sufficient to work with for AD algorithms for Jacobian computation, but not for Hessian computation, since the graph does not capture nonlinear interactions between variables. In 2012 Gower and Mello introduced a symmetry-exploiting graph model for Hessian computation in which the computational graph of the function is augmented with additional edges representing nonlinear interactions. Using the model, they outlined an approach called edge_pushing for Hessian computation. However there was no correct and efficient implementation of the approach so far. We extend the theory of the edge-pushing algorithm, efficiently implement the algorithm within the AD tool ADOL-C and provide preliminary experimental results comparing the edge-pushing algorithm with an established method for computing sparse Hessians via graph coloring.
- Won, Jongho
- Yazawa, Kazuaki
- Yeung, Yu Hong; Solving Linear Systems of Equations for Surgical Simulations
Authors: Yu-Hong Yeung, Jessica Crouch and Alex Pothen Department of Computer Science, Purdue University and Old Dominion University
We present a ﬁnite element solution method that is well-suited for interactive simulations of deformation and cutting. Our approach features the use of pre-computed sparse LDL^T factors to solve a Schur-complement system that accounts for changes in mesh connectivity and boundary conditions. The Schur complement is not explicitly formed, but solved with a Krylov solver that forms matrix vector products as needed. Updates are accomplished through augmentation of stiffness matrix factors to maintain their consistency with changes to a model. As changes accumulate over multiple simulation timesteps, the augmented solution method slows. However, by repeatedly re-factoring the stiffness matrix in a concurrent background process, fresh matrix factors that incorporate recent model changes can periodically replace the initial factors. This limits the expansion of the augmented matrices and provides a way to maintain a fast solution rate as the number of changes to a model grows. The complexity analysis and experimental results for this method demonstrate that it scales well with problem size. Results for cutting and deformation of 3D linear elastic models are reported for regular meshes with node counts ranging from 100 to 25,600 and irregular mesh with 20,133 nodes, and these show potential for real-time interactivity. Our preliminary results show that our algorithm clearly outperforms the conjugate gradient method when stiffness matrix is not well-conditioned. This work has applications in contingency analysis in electric power grids.
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