MIT Reports to the President 1997-98
The mission of the Laboratory for Electromagnetic and Electronic Systems (LEES) is to be the focus for research and teaching in electric energy from its production through its processing to its utilization, and in electromechanics from the macroscopic through the microscopic to the molecular levels. Electric energy and electromechanics are defined broadly to include power systems monitoring and operation; automatic control; power electronics; high voltage engineering; and conventional, continuum and biological electromechanics. Much of the work of the laboratory is experimental, and industrial sponsorship represents a large fraction of the laboratory's support. The laboratory's professional staff consists of 10 faculty from EECS, one Senior Lecturer, 2 Senior Research Engineers, 5 research staff, and approximately 50 graduate students. The laboratory faculty and most of the staff are heavily involved in both undergraduate and graduate teaching. Faculty from the departments of ME, CE, MS&E and NE are collaborators in many of the laboratory's programs, and there are extensive joint activities with the Microsystems Technology Laboratory (MTL) and the Energy Laboratory. LEES is also an active participant in the Leaders for Manufacturing Program, and the Technology and Policy Program (TPP). During the past year the laboratory has experienced a continued expansion of its automotive related research, demonstrated a sensor technology capable of detecting plastic landmines, demonstrated an actively controlled polymer gel synthetic muscle, and successfully applied advanced signal processing techniques to the evaluation of insulation integrity in high voltage power cables.
AUTOMOTIVE ELECTRONICS AND ELECTRICAL SYSTEMS
Professor John G. Kassakian and Dr. Thomas M. Jahns lead the laboratory's work in automotive electrical and electronic systems. This work is sponsored primarily through the laboratory's Consortium on Advanced Automotive Electrical and Electronic Components and Systems. Seven new members were added to the consortium in the past year, bringing the membership to 20. The consortium sponsored three two-day meetings, one of which was hosted by Siemens and held in Regensburg, Germany.
Under the auspices of the consortium, the multi-attribute trade-off analysis tool MAESTrO has been licensed to a commercial software developer. Professors James L. Kirtley and Jeffrey H. Lang, Dr. Jahns and graduate student Edward C. Lovelace have continued their investigation of high-power starter/alternators for future cars. After comparing the performance of several candidates, they have selected the interior permanent-magnet synchronous machine for further investigation. The analysis and optimized design of this machine is now in progress, with the fabrication and testing of a prototype machine planned for later this year. New consortium research projects have been initiated on protection and fusing for a 42 V system, a comparative study of practical 42 V architectures, an evaluation of EMI and mitigation techniques, and an economic analysis of the process of transitioning the industry to the proposed 42 V standard, this last in collaboration with the MIT Material Systems Laboratory and the Sloan School.
Also under the auspices of the consortium, Prof. Kassakian participated in a three-day BMW technology workshop and a strategic review of Ford's internal electrical system development program, and Dr. Jahns participated in, and presented the work of the consortium to, the first General Motors Technology Fair.
The Laboratory's strategic alliance with Ford to accelerate the adoption of a 42 V standard has been expanded to include Daimler Benz, Siemens and Motorola. This group has been actively engaged in developing the tools and techniques for remote collaboraton. As part of this activity, Prof. Kassakian has organized a technical session at Convergence 98 - an international conference devoted to automotive electrical/electronics - to present the international status of the transition to 42 V.
MODELING, MONITORING AND CONTROL OF POWER SYSTEMS
Utility industry restructuring has placed an intense focus on achieving economically optimal system operation by employing new and more sophisticated control and monitoring strategies. LEES has been making significant contributions to the solutions of problems of power system modeling, economic control, and apparatus monitoring.
MODELING AND CONTROL
Professor Bernard C. Lesieutre has conducted new research in the area of uncertainty analysis of large scale power system simulations. He has applied a promising probabilistic technique to help evaluate load model uncertainties when estimating maximum power transfer limits between areas. Given a power transfer level, he has calculated the probability that the response to a contingency (unexpected system event) will exceed some voltage, frequency, or thermal limit. The "probabilistic colocation method," which is employed in this study, was originally developed to study uncertainty in global climate change research. In the power system problem, this computationally efficient method is approximately three orders of magnitude more computationally efficient than the common Monte Carlo approach, and a single order of magnitude more efficient than other variance reduction techniques. Prof. Lesieutre's continuing work will identify the critical uncertain parameters for a particular system.
Professor George C. Verghese and Prof. Lesieutre have received a third round of funding from Electricité de France to further develop their ideas for reduced-order dynamic modeling of power systems. Their work so far has shown that traditional models can be substantially reduced in complexity without significantly compromising accuracy. The next phase of research is focused on obtaining comparable (order-of-magnitude) reductions in simulation time, with a view to enabling a variety of real-time applications in power system operation.
In collaboration with colleagues from Northeastern University and the University of Padova (Italy), Profs. Verghese and Lesieutre have further developed the notion of dynamic phasors models for efficient representation of nearly periodic dynamics in power electronic and electrical machine components of large power systems. This approach has led to novel and tradctable dynamic models of components such as thyristor controlled series compensators, which are finding increasing use in power systems.
Senior Scientist Marija Ilic, in collaboration with Professor Francisco Galiana of McGill University and the Energy Laboratory's Electric Utility Program, continues to grow the Consortium on Transmission Provision and Pricing Under Open Access. The consortium is studying issues related to the operational stability of the regional power grid in the face of the relaxed control over individual generators implied by the deregulation of the electric utility industry. A very successful workshop on this topic was hosted by Dr. Ilic and her colleagues this year.
ADAPTIVE MONITORING OF TRANSFORMERS
New methods for the early detection of defects in on-line power transformers developed by Principal Research Engineer Chathan Cooke have now been applied to several field study cases. The system uses advanced pulse signal measurement at multiple locations followed by time and frequency domain signal processing to identify and locate incipient partial discharge events. Further development, including commercialization of the method is proceeding.
Research Engineer Wayne H. Hagman and Dr. Cooke have initiated a program with Entergy Services, Inc. to use adaptive modeling to enable more effective use of capital intensive power transformers, and to develop sensors and models for the detection and quantization of deterioration in transformer load tap changers.
Mr. Hagman continues his long-standing association with Boston Edison to deploy the MIT transformer monitoring system into the Edison network. His successful training of Boston Edison employees has enabled the transfer of operational and maintenance responsibilities for the installed systems to Boston Edison. Under Boston Edison funding, Mr. Hagman is developing means of performing on-line intelligent diagnosis of anomalous behavior in power transformers.
The laboratory continues its search for an appropriate partner with which to commercialize and continue the development of the MIT monitoring system. Discussions with two companies in the US and one in Great Britain are underway.
NON-INTRUSIVE LOAD MONITORING
Professor Steven Leeb, graduate student Steven Shaw and former student Umair Khan were this year awarded a second patent on an advanced hardware platform for nonintrusive load monitoring. Custom hardware constructed in the laboratory implements a parallelized indetification algorithm and computation platform using an array of inexpensive microcontrollers. A field portable version of the nonintrusive monitor was designed using a digital signal processing chip and a Pentium class processor. Four of these units have been constructed, and field testing has begun. Some of these units will be installed in MIT's Next House dormitory to assist the MIT Physical Plant with electrcial end-use load monitoring and diagnostics.
Professor James L. Kirtley and graduate student Ujjwal Sinha have produced the final version of the Novice Design Assistant, a computer aided tool for designing three-phase induction motors, and delivered it to the sponsor, Magnetek. Mr. Sinha has also developed a new optimization technique that uses multi-dimensional adaptive regressive splines, fitted to the pareto frontier data produced by the Novice Design Assistant.
GEL POLYMER ACTUATORS
Professor Leeb, in collaboration with Professor Toyoichi Tanaka of the Center for Materials Science and Engineering, and with graduate students Ahmed Mitwalli and Tim Dennison, continues to explore applications of polymer gels as actuators and sensors. Responsive polymer gels have been successfully employed as electrophoretic and chromatographic media in which distributions of phase transition temperatures in a gel can be used to identify ionic components in a mixture. A remarkably descriptive and accurate model of responsive gels as linear actuators was developed this year and used as a basis for control design. A simple synthetic muscle was actively controlled using this model and a microcontroller. Professor Leeb was awarded a patent this year for the design of gels that exhibit a phase-transition in response to an applied magnetic field, a result of work that was described in last years report.
Professor Jeffrey H. Lang, Principal Research Engineer Stephen D. Umans and graduate student Steven F. Nagle, in collaboration with many faculty, staff and students from across the School of Engineering, have continued their development of motors and generators for microturbomachinery. Optimized machines have now been designed and are under fabrication. Professor Lang and graduate Jo-Ey Wong, in collaboration with Professor Martin A. Schmidt of the MTL have continued their development of microelectromechanical relays for power witching. Prototype relays are currently under fabrication. Finally, Professor Lang, Professor Anantha P. Chandrakasan, and graduate students J. Oscar Mur-Miranda, Rajeevan Amirtharajah and Scott E. Meninger have begun the development of microelectromechanical devices designed to convert ambient vibration energy into electric energy to power autonomous electronics. Initial devices have been designed and are now under fabrication.
Postdoctoral Research Associate David J. Perreault, working with graduate students Vahe Caliskan and Tim Neugebauer, completed the design and construction of a prototype dc/dc converter for use in the new 42 V automotive electrical system being developed by Ford. The design is based on the cellular converter concept which was the subject of Dr. Perreault's doctoral thesis, and takes advantage of interleaving to reduce filter requirements, and subsequently cost. The converter has been delivered to Ford and is being tested as part of their 42 V prototype system.
Professor Leeb and former graduate student Deron Jackson completed development of an inductively coupled power supply system for servomechanical systems. This power electronic drive has been used to charge electric vehicle batteries, and to run servomechanisms including a water bath and a rotational velocity servo. Adaptive control was designed, implemented, and tested using this power electronic drive. Undergraduate student Ben Douts has applied the inductive techniques to the development of a magnetically coupled "smart card" system, which demonstrated power transfer and bidirectional serial communication at 9600 baud over a common magnetic path.
HIGH VOLTAGE AND INSULATION RESEARCH
Dr. Cooke and graduate student Robert Lyons have further developed signal processing for ultrasonic inspection methods, including one specific application to high-voltage power cables under sponsorship of the Tokyo Electric Power Company. Through signal processing, improved spatial resolution and better localization of features have been achieved. The method has been demonstrated on the ultrasonic measurement of space-charges within plastics. In one case electrons directly implanted into a polymer were clearly located and their motion within the dielectric was tracked. Another example concerns ultrasonic observation of the dielectric failure process called "treeing." Here simultaneous micro-video and ultrasonics enable new information about this basic failure mechanism.
Professor Markus Zahn has extended his work on Kerr electro-optic field mapping to develop a complete three-dimensional mathematical formulation of optical tomography. Using this formulation, the magnitude and direction of an applied electric field for any arbitrary electrode geometry can be determined from light intensity measurements that depend on electric field induced birefringence.
Professors Lesieutre and Zahn, under a joint NSF/EPRI initiative, have continued work on developing a sensor and algorithms to estimate spatial profiles of conductivity and permittivity in materials. Over the past year they have redesigned the sensor to improve its performance and have conducted experiments to study the diffusion process of moisture between oil and pressboard to better understand and quantify the flow electrification problem in transformers. This process can lead to transformer failure when a cold transformer is energized. In the process of this investigation, Profs. Lesieutre and Zahn have also identified and are correcting errors and shortcomings that appear in the literature concerning moisture diffusion. Professors Zahn and Lesieutre have also extended their work on interdigital dielectrometry sensors to show that these sensors can detect plastic landmines that current metal detectors cannot detect. They have received a US Army contract to further develop dielectrometry technology for landmine detection.
Professor Martha Gray has left the laboratory to assume the permanent role of co-director of the MIT/Harvard joint program in Health Sciences and Technology (HST). Dr. David Perreault, formerly a graduate student in the laboratory, completed his doctoral program and has joined the laboratory as a Postdoctoral Research Associate.
Professor Gerard Hurley of University College, Galway, Ireland, has been on sabbatical in the laboratory as a Visiting Professor. Dr. Stephan Guttowski who recently received his degree from the Technical University of Berlin has joined the laboratory as a Postdoctoral Research Associate.
HONORS AND AWARDS
Professors Verghese and Lang were elected to the grade of Fellow in the IEEE.
Professor Leeb was this year's recipient of the Harold Edgerton award for excellence in undergraduate teaching.
Professor Kassakian received the IEEE Power Electronics Society's Distinguished Service Award, and the Dikran K. Kabakjian Science Award from the Armenian Students Association of America.
MIT Reports to the President 1997-98