Vijay Vittal - US grants

The objective of this project is to extend the range of studies that can be performed using direct stability analysis techniques. The transient energy function method (TEF) has been used successfully in direct transient stability techniques assuming a classical power system model. The classical model is satisfactory for the initial analysis of many power system stability problems. However, a large set of problems of critical concern to utility planners and operators requires more sophisticated models to obtain realistic results. Hence, there is a need to develop direct methods using more sophisticated models. This project will consist of extending the classical model in the following areas: including detailed synchronous machine models and effect of fast exciter systems, incorporating HVDC terminal effects remote from disturbances, and modeling the effect of relay operations.

The proposal is aimed at transferring the implementation of certain large-scale system stability calculations (the so-called Transient Energy Function) from its current serial-computation environment. Since these algorithms are intended for eventual use in an on-line decision making environment, demonstration of a significant speed advantage gained by large-scale parallel coputation, together with the experience of remote computational access is crucial to continuation of scientific inquiry into the technique.

This is a SGER project on a controversial subject: transient stability methodology for electric power systems. The investigators are examining new indices and measures for transient stability including measures of security margin, critical parameters, critical contingencies, vulnerability, and indices of stress. The project includes methodologies which are capable of direct calculation of these parameters. Additional project foci include expert system sorting of stability indices and on-line methodologies. The project is controversial in that it is at odds with traditional methods and their use for transient stability assessment.

The proposed research deals with the analysis of interconnected power networks when subjected to large disturbances such as the loss of a generating unit. The vast majority of analytical work on power system dynamics deals with system behavior in response to small disturbances. In such cases linearized analysis is appropriate. For large disturbances, nonlinear interactions can play an important role. The approach used in this research extends energy-based methods to account for modal interactions.

The principal goal of this project is to develop a novel and unique undergraduate laboratory in control system. The laboratory provides hands-on experience in the various steps of control systems design, aids students in visualizing the abstract concepts covered in a control system course, introduces students to the practical aspects of design, and provides an avenue to synthesize theoretical materials developed in a lecture. This project is setting up a computer-controlled control system design laboratory to support undergraduate courses and design efforts. The laboratory includes four novel design experiments, specifically designed to stimulate the students and to demonstrate the practical and analytical issues in control system design and development. The project is using this "hands-on" integrated capability to provide a complete design and analysis experience. This includes model development and verification, model simulation, control design, system implementation, and verification of performance objectives. Modifications to original designs can be included and parameters can be fine tuned. Students are confronted with design and analysis activities similar to those faced by engineers in industry.

ECS-9810081 Khammash In recent years, the North American Electric Interconnection has undergone major changes with the advent of a competitive market place, and deregulation. These changes will impose new requirements on system operation and planning. It is likely that the emergence of open access, and wheeling of power in a competitive market place will drive the need to operate and plan the system at higher levels of loading, leading to further stress on the system. To a large extent, adequate system dynamic performance will depend on the proper operation and performance of critical controls. Proper design and robust performance of these controls are essential for the reliable operation of the interconnected power system. This proposal deal with development of techniques to apply modern robust control methods to design and analyze controls for large scale power systems. We propose to extend existing methods of robust stability analysis to deal with large scale power system problems. Specifically we intend to use the Structured Singular Value approach, and develop analytical and numerical techniques to exploit the structural characteristics of large power systems. We will investigate and develop numerical techniques which are suitable for large scale problems. The developments would involve issues related to uncertainty characterization and parameter selection, frequency sweeps, state space methods utilizing branch and bound techniques, and efficient techniques for control synthesis. The methods developed will be applied to realistic test systems obtained from two North American Electric Utilities.

ABSTRACT
EEC-9908690
VITTAL

The five-year continuing award funds Iowa State University to be a new research site of the multi-university Industry/University Cooperative Research Center (I/UCRC) for Power Systems. This new research site is being added to the lead research site at Cornell University and the University of Illinois-Urbana Champaign, University of Wisconsin-Madison, University of California-Berkeley, and Washington State University.

The Iowa State University research site's research agenda will address 1.) System Optimization Using Risk Based Security and Distributed Knowledge 2.) Market Interactions and Market Power, 3.) Robust Control of Large Scale Power Systems, 4.) Voltage Stability Constrained ATC Calculation and 6.) Chaotic Load Models for Power Systems.

This proposal explores new concepts for the damage assessment, control, and restoration of the electric power grid following catastrophic disturbances. These disturbances would include:

1. Natural disasters like earthquakes, tornadoes, ice storms, wind storms, and large electrical impacts like short circuits, and failure of major components.
2. Man-made disasters, such as terrorist attacks, and human errors.

The damage assessment consists of determining the severity based on the following criteria:
a) Degree of damage, b) Degree of danger, and c) Extent of hazard. This type of analysis will require input from a well-established information and sensing system. The complexity of the problem is further increased because of the large geographical expanse of the Electric Power Transportation system. The use of a wide array of communication technologies including GPS, Microwave Networks, Internet, low earth orbit satellites, and other communication networks will be examined as a part of the information. Infrastructure.

Issues related to the scheduling and processing of real time information will also be carefully examined. Key requirements for the computing and communication infracture to support real time supervisory control and data acquisition of large electric power grids are identified. Information and computing architectures to meet these requirements will be proposed.

Various control strategies to prevent and minimize the extent of the dislocation of the electric network will be compared. Concepts of graceful degradation as applied to the electric power grid will be proposed. This aspect of the work would also involve corrective strategies to facilitate fast restoration. Newer configurations for the electric power distribution networks and their control and protection equipment so that the network responds to emergencies in a more controlled manner will also be explored.

The final step in the investigation will deal with approaches for the restoration of the system following catastrophic disturbances. This is one of the least analyzed aspects of large power grids. It is a highly complex undertaking and involves several issues that relate to automatic restoration as will as manual switching that involves a variety of manpower issues.

It is important to note that the power delivery network is overlayed with several hierarchical information and control networks that provide various functions dealing with supervisory control data acquisition, and transaction information in the new deregulated electric utility environment. The roles of each network layer will also be carefully identified.

The effective operation of power systems in the present and the future depends to a large extent on how well several emerging challenges are met today. Power systems continue to be stressed as they are operated in many instances at or near their full capacities. Addition of new transmission lines to relieve this stress is often very difficult and is mired in regulatory procedure. The new deregulated environment has the potential of exacerbating this stress as more power is shipped from longer distances. At the same time, new flexible ac transmission system (FACTS) devices are being commissioned in various locations. While these devices can offer significant performance improvements and may help alleviate some of the problems alluded to; they do have unique dynamic properties that are less familiar than those of existing devices. In addition proper design and analysis of control systems for FACTS is crucial for efficient operation. The resulting dynamic behavior of the overall system that incorporates these FACTS devices is not well understood. Consequently, the potential benefits of these devices may not be fully realized. The market mechanisms in the future will have a bearing on the operating conditions and the transaction contracts that are established. Since the market would be geared to fully utilizing efficient generation, additional stress would be imposed on the transmission grid in certain locations. New technology involving distributed generation is being rapidly introduced in the system to meet growing demand. As a result several important technical issues related to system interconnection, reliability, and location need to be addressed. These important issues call for work in the areas of real time control, sensing, communication, economics, modeling, and analysis of large scale systems.

We propose to conduct a workshop that will bring together researchers, scientist, and federal agency participants in the areas described above. Selected participants will present position papers and discussions that address key research issues will be conducted. The workshop will focus on identifying emerging problem in power systems that can benefit from the system and control theoretic developments as well as presenting new research ideas in the control, operation, and economics of large networks and their application to power systems. The outcomes of the presentations and discussions will be used as the basis to identify future research needs in the area of large-scale power systems and the means by which such needs can be met. The presentations, discussions, and recommendations for future research will be published in the workshop proceedings.

This project will develop (a) design theory and method for planning hybrid (discrete and continuous) power system controllers, and (b) economic systems, applicable to power systems utilizing energy markets, for recovering and allocating costs of the design and installation of such controllers. Discrete-event system theory, together with integer programming optimization methods, will be utilized in the control design approach. The economics thrust, to be heavily emphasized in this project, will draw on the theory of public economics to determine the level and manner of regulation necessary in a market designed to provide an appropriate amount of power system control. The impact of additional control on the locational marginal prices (LMPs) will be studied to determine the value of the control. These approaches will be illustrated using three different and increasingly complex testbeds, with the most evolved being the 6000 bus model of the western US interconnection. New courseware will be developed that links the economics, control, and power systems issues addressed in the project, and this courseware will be utilized in the graduate curricula of both the EE and Economics departments at Iowa State University. Effort will be made to attract to this project minorities and women undergraduates (funded under an REU) and graduate students (funded as GRAs). An important aim of this project is to expose the excitement of our disciplines to high school students. We intend to involve teachers from high schools in surrounding areas in a RET effort and provide exposure to the discipline. We also involve an industrial advisor who brings practical aspects to this proposal. Two PhD students who have a broad background in electric power engineering, control theory, and economics will add to the nation's scientific work force.

The electric power system in North America has undergone unprecedented changes with the advent of a competitive market place and deregulation. These changes in the system have resulted in higher levels of loading on the system, and have further increased its stress. At the same time, the transmission grid has seen very little expansion due to the prevailing economic conditions and the lack of incentives in the market. As a result, available transmission and generation facilities are highly utilized with large amount of power interchanges among companies and geographical regions. It is envisioned that this trend will continue to grow and result in more stringent requirements to maintain reliability and adequate system dynamic performance. To a large extent, critical controls like excitation systems, power system stabilizers (PSS), static VAR compensators (SVC), and a new breed of control devices driven by modern power electronics and referred to as flexible ac transmission systems or FACTS play a key role in maintaining adequate system dynamic performance. Proper design of these controls resulting in robust system-wide stability and performance is essential. With the increased emphasis on reliability and system dynamic performance there is a greater need to analyze and design controls in an integrated fashion, taking into effect the interaction between the various kinds of controls. We propose to apply gain-scheduling techniques to enable the use of a family of robust controllers. More specifically, we propose to explore the use of linear parameter varying (LPV) approach to gain scheduling. This is a relatively recent approach that has not been seriously explored for large power systems. On the other hand, LPV gain scheduling methods are gaining acceptance in aerospace applications following their successful use in flight control systems. In these applications, one observes wide changes in the operating conditions (e.g. altitude, airspeed) similar to those seen in power systems.

Specifically, we will address the following topics:

Development and application of linear parameter varying (LPV) gain scheduling methods of control design to large power systems accounting for large changes in operating conditions.

A novel decentralized control design for large-scale power systems.

Broader Impact

The project addresses a critical need for the reliability of the national electric grid dealing with the efficient design of controllers. The project also propose a novel decentralized approach to controller design for power systems that will significantly reduce the computational burden for large power systems but still take into account the uncertainty associated with changing operating conditions. This will provide initial testing of the approach and provide insight into the development of more elaborate techniques for designing controls. The analytical basis for the approach will also be developed.

The project will support 1 PhD student for a year. This will contribute to the nation's scientific work force and produce an engineer with advanced capabilities to tackle the important issues related to the reliability of national electric grid.

This action renews activities at Iowa State University for the multi-university Power Systems Engineering Research Center (Pserc) headquartered at Cornell University for the two remaining years in the Industry/University Cooperative Research Centers (I/UCRC) Program. The Iowa State University has been an active participate in the PSerc I/UCRC and has participated in several activities including recruiting six new companies into the center. The investigators at Iowa State University have also been involved in several research projects that have been completed and several that are in progress.

The events of September 11, 2001, have highlighted the impact of malicious attacks on critical national
infrastructure components. This has resulted in an increased appreciation for improving the physical security of
critical electric power system components like substations, transmission lines, and generators. These observations
together with the major North East blackout of August 14 th , 2003 highlight the importance of the electric grid as an
energy transport medium and its critical importance to the nation's economy and global competitiveness.
The electric power grid is a highly automated network. A variety of information networks are interconnected to the
electric grid for the purpose of sensing, monitoring, and control. Any disturbance or dislocation in the electric
network is sensed primarily by observing the electrical behavior of the power system via the observations and
analysis done using the data obtained using measurements of electrical quantities. The sensor technology that
aids the deployment of distributed sensing systems has improved vastly in the recent past. However, even though,
standards do exist for physical security of substations, very few modern sensing mechanisms have been utilized to
meet the physical security standards.
With this scenario in mind we will undertake the following research in the sensing and information processing of the
electric grid: (1) examine new sensors to sense physical quantities in power systems; (2) design a wireless sensor
information network to transmit these measurements to the central control center; (3) develop algorithms for sensor
placement, data aggregation, fault diagnosis, and load balancing for the sensor information network; and (4) fuse the
physical sensor data with conventional electrical sensor data to devise more effective control strategies following
large disturbances. We will demonstrate the developed techniques and validate them on a test bed that we have
created to emulate a large power system using an operator training simulator. The key elements of the proposed
approach consist of the following steps:
1. Design structure of the wireless sensor information network that maintains connectivity under a variety of
contingency scenarios in two modes, a) Partial mode that helps in detection of failures, and b) Full mode which
helps in diagnosis of the problem.
2. The sensor network in Partial Mode will be used to zero in on portions of the power grid where the system
would like to get physical sensor information to fuse with existing electrical sensors to detect disturbance, and
or catastrophic failures based on: a) On-line risk based engine, b) Unusual or abnormal measurements from
certain sensors like temperature, motion, or chemical sensors, or c) Weather and unusual conditions.
3. This leads to a decision on transferring to Full Mode operation where more information collection via sensor
activation and deactivation, communication network connectivity, and power usage considerations will be made
from the critical local portion of the power grid identified by the above analysis.
4. This information leads to further diagnosis of the network condition that is used by central control center to
invoke appropriate control action to safeguard the power network.
Intellectual merit of the proposed research lies in developing novel concepts for integrating a broad range of
sensors that monitor both physical security and operational security of the nation's most critical infrastructure the
electric grid. The project aims at using the combined data from these sensors together with the detailed development
of the associated communication and information network to enhance the security and reliability of the power grid.
The team has combined their expertise to take a fresh view at the different kinds of sensors currently available and
extract appropriate data from them for several key issues related to power system physical security.
The broader impact of this research will be two fold. First, it will enhance the state of art in sensing, monitoring,
and controlling the electric power grid by combining the multidisciplinary expertise of the investigators. Second, the
new sensor network will be applied to develop an emergency response system for the national electric grid, which is
essential to the vitality of the nation's economy, and will provide protection to it.
Education: Our educational goal is to train the next generation of students, train new cadres of doctoral researchers
and most importantly, share the excitement that comes with working in engineering with the youngest of students, in
the K-12 program, to attract them into science and engineering. The college of engineering at Iowa State University
has a dedicated effort to attract minority scholars into the graduate program and the university has an ongoing
program to employ high school students and teachers in research programs during the summer. We will leverage
these efforts.

The effective operation of power systems in the present and the future depends to a large extent on how well several emerging challenges are met today. Power systems are experiencing increasing stress as they are operated in many instances at or near their full capacities. At the same, addition of new transmission lines to relieve this stress is often very difficult and is mired in slow regulatory procedures. The blackout on August 14th, 2003 in the Northeastern US clearly showed that the stressed power system is clearly vulnerable to cascading failures and can result in widespread outages that can affect millions of people and bring modern day life to a stand still. This two-day workshop will bring together invited speakers whose research interests lie in the areas of power system dynamics and control associated with the analysis of large disturbances in power systems.

Intellectual merit: This workshop will: one, create a venue in which engaging discussions among researchers can take place; two, present new research ideas in understanding and preventing cascading outages in power systems; and three, outline the challenges and future research needs in this area. Broader impact: The workshop funded by this proposal will generate technical issues for research relating to preventing cascading outages in large power systems. This is a topic of critical importance to the economic viability of the nation. The results of this workshop will identify new directions for research to harden the electric supply system and improve the reliability.

The objective of this research is to examine the impact of increased doubly fed induction generator (DFIG) based wind generation on power system dynamic performance. The approach in this project deals with examining the following issues:
1. Analysis of increased penetration of DFIG wind turbine units on transient stability
2. Design of power electronics based control to mimic effect of inertia and enhance transient stability performance
3. Verification of the performance of the proposed controller in improving transient stability performance

Intellectual Merit:

The intellectual merit of the project consists of a novel approach to increase the potential for penetration of a valuable renewable resource which could have a significant impact on reducing environmental concerns and the nation's reliance on foreign energy resources. This is a core issue for the US in order to maintain it global leadership and productivity. Providing advanced controls to maintain the reliability of the transmission grid will guarantee electric energy delivery and economic viability.


Broader Impact:

In terms of broader impacts the project brings together two investigators from two different areas of research expertise in a well integrated project that combines the complementary expertise of each investigator. An important aim of this project is to expose the excitement of our discipline to high school students. The results from this project will be widely disseminated through the various meetings of this center and also through Internet seminars that are held every week to provide industry and university members exposure to research activities in the center.

Abstract
Abstract (NSF 1035906):


The objective of this research is to establish a foundational framework for smart grids that enables significant penetration of renewable DERs and facilitates flexible deployments of plug-and-play applications, similar to the way users connect to the Internet. The approach is to view the overall grid management as an adaptive optimizer to iteratively solve a system-wide optimization problem, where networked sensing, control and verification carry out distributed computation tasks to achieve reliability at all levels, particularly component-level, system-level, and application level.

Intellectual merit. Under the common theme of reliability guarantees, distributed monitoring and inference algorithms will be developed to perform fault diagnosis and operate resiliently against all hazards. To attain high reliability, a trustworthy middleware will be used to shield the grid system design from the complexities of the underlying software world while providing services to grid applications through message passing and transactions. Further, selective load/generation control using Automatic Generation Control, based on multi-scale state estimation for energy supply and demand, will be carried out to guarantee that the load and generation in the system remain balanced.


Broader impact. The envisioned architecture of the smart grid is an outstanding example of the CPS technology. Built on this critical application study, this collaborative effort will pursue a CPS architecture that enables embedding intelligent computation, communication and control mechanisms into physical systems with active and reconfigurable components. Close collaborations between this team and major EMS and SCADA vendors will pave the path for technology transfer via proof-of-concept demonstrations.

PSERC is proposing a Phase III support (third five-year period) for the Center, including support for center personnel, evaluation and research. The proposed Center is a multi-university Center comprised of the following universities: Arizona State University (lead), Cornell University, Texas A & M, Howard University, Washington State University, the University of Wisconsin-Madison, Iowa S ate University, Wichita State University, Georgia Tech, the University of Illinois at Urbana Champaign, the University of California-Berkeley, and Colorado School of Mines.

The proposal from PSERC seeks funding for a Phase III (3rd five-year period) led by Arizona State University (ASU). PSERC had its origin as a multi-university IUCRC in 1996, and was created with the vision that collaboration amongst a large group of academic, industrial, and governmental institutions can develop solutions to the complex problems in electric energy. PSERC (currently comprised of 12 universities) will conduct research organized under three primary research stem areas: markets stem, system stem, and transmission and distribution technologies stem. PSERC leverages the expertise of some 40 multidisciplinary researchers. The PI and all of the other site directors are very well-qualified and have access to appropriate and adequate resources.

The proposed work addresses important improvements and advancements in the transmission and delivery of electricity. PSERC has been a leader in in developing several key concepts with regard to the development of electricity markets. PSERC researchers also developed one of the first large scale visualization tools for the electric power industry, and this effort has resulted in the creation of a company that has commercially developed the tool. Over the past six years, PSERC member companies have employed an average of 80 graduate and undergraduate students per year from PSERC universities. In the area of diversity, one of the PSERC member universities is Howard University, a historically black university. PSERC will continue to seek women and minorities through students and faculty at member universities as well as on an individual basis as research associates.

1541026 (Vittal). Resilient, reliable and efficient critical infrastructures are essential for the prosperity and advancement of modern society. The electric power grid and the water distribution system are among the most critical infrastructures. They are highly automated and interdependent. A range of sensors, communication resources, control and information systems together form the cyber networks that are an integral part of these infrastructures and contribute to their efficient, reliable, and safe operation. This project will (1) build mathematical models capturing the interdependencies between the electric and water systems and simulate their operation in time, (2) develop innovative behavioral models of consumer demand for electricity and water under extreme scenarios, (3) simulate demand under these extreme scenarios and propose control actions to mitigate detrimental impacts, and (4) enable internetworking between the cyber systems of the two infrastructures using middleware gateway deployment and emulate it in simulation to determine the effect of the shared information from sensors on the control actions under the extreme scenarios. With the predicted mega droughts in the southwest, an interdependent model as proposed is expected to significantly benefit electric and water utilities by enhancing their ability to perform scenario analysis coupled with consumer usage data to determine the impacts of severe droughts on each of the infrastructure systems and benefit society at large. Interdependent control of the two systems will help optimize water usage and electricity production to cope with severe environmental conditions. A clear understanding of the factors that impact behavioral responses to water and electricity use under extreme conditions will inform governments, suppliers, and the public about effective methods to address real-world challenges such as mega droughts. Findings of this work, including a test best based on realistic data, will suggest strategies for informing social practices and behavioral changes in conserving electricity and water resources. These capabilities could provide significant benefits to nations across the world and enhance sustainability of scarce natural resources.

The project will develop a system dynamics-based mathematical model of two interdependent critical infrastructure systems, namely electric energy and water supply, and identify key interdependencies between the two systems. The overarching goal of the research is to transform interdependent but "independently operated" infrastructure systems of today into resilient infrastructures, through efficient information exchange enabled by inter-networking that can handle forecasted extreme scenarios using innovative behavioral models of consumer demand and sophisticated control. The following research and educational tasks are included. Task 1: Development of a system dynamics based mathematical model of the interdependent infrastructures. (a) Electric infrastructure, (b) Water delivery and treatment infrastructure, (c) Identification of their interdependencies, and (d) Simulation of interdependent systems. Task 2: Extreme Scenario, social/behavioral model based contingency selection and analysis (a) Behavioral model of consumer demand of commodities supplied by infrastructure under extreme scenarios. (b) Risk assessment of interdependent system and contingency selection for extreme scenarios. (c) Analysis of model under extreme scenarios and associated contingencies. Task 3: Analysis and control of interdependent infrastructures (a) Formulation of interdependent control, (b) Implementation and simulation of designed control, (c) Examination of the ability of control to mitigate detrimental effects of extreme scenarios. Task 4: Optimal middleware gateway deployment for inter-networking between infrastructure information systems (a) Middleware development and emulation, (b) Control implementation with middleware-enabled shared information and comparison of control efficacy with the independent information setting in Task 3. Educational outreach integrates research into education and outreach by (i) Interdisciplinary graduate course offering, (ii) Short course and webinars for industry partners, (iii) Self-study modules on interdependent infrastructures and (iv) Web based module development of extreme scenarios and operation of infrastructure systems for K-12 students.

Abstract
The proposal supports an international workshop between researchers from the U.S. Japan, Norway, and India on the fundamental scientific issues related to power system resiliency and the integration of distributed energy resources like photovoltaic solar resources, wind energy resources and a variety of storage devices. Unlike conventional fossil fuel, hydroelectric or nuclear fuel based electricity generation, distributed energy resources are inherently uncertain and could significantly affect power system resiliency. This workshop between researchers from four countries that have experienced significant penetration of renewable resources will examine the critical issues affecting power system resiliency due to the increased penetration of renewable resources and identify key areas of collaborative research to arrive at innovative solutions to enhance power system resiliency and reliability. The Indian Institute of Technology (IIT), Bombay, India, will host the two-day workshop. The invitees to this workshop will be identified and invited by the workshop organizing committee.

The increasing integration of spatially distributed renewable resources and storage devices and the modernization of computing and communication systems have contributed to increasing the complexity of interactions between constituent cyber and physical layers of the power system. Nevertheless, the systematic utilization of large data sets to inform distributed decision making-notable opportunities attributable to the generational changes highlighted previously-can improve resiliency, economy, operational efficiency, power quality, and availability. The proposed workshop, will be organized in India in January 2019, will outline the foundational science for power system resiliency and distributed energy management systems. A unique feature of the meeting is that it will bring together researchers from the US, Japan, India, and Norway; in this regard, it is anticipated that technical discussions will result in solutions that have global impact.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.