The professional group on Energy conducts state-of-the-art research to meet future needs in power systems and power electronics. The primary impetus for the research projects undertaken stems from the technological innovations and developments that have taken place in the last two decades in the areas of computers, communications, control and materials technology. The quality of this research program is in the top five in the country.
The Energy Group, consisting of seven faculty members, has been developing state-of-the-art techniques in the following five major areas:
Distribution system planning and operation: The advent of Geographic Information Systems and other technological developments have opened avenues for automating the planning and operation of distribution systems.
Intelligent systems applications to power systems: The emphasis is on the investigation of modern methods such as expert systems, neural networks, intelligent decision support systems, and genetic algorithms for a host of power system problems.
Industrial power electronic applications: The design, development, modeling, simulation, and field testing of custom power devices such as Adaptive Var Compensators has been underway. In addition, research on better methods for solid-state control of motors and other industrial applications are being investigated.
Power electronic modeling and simulation: Detailed modeling of the latest power electronic devices such as diodes, thyristors, MOSFETs, IGBTs and MCTs, in conjunction with development of improved forms of these devices, is the thrust of this research specialty.
Power system planning and operation: The focus in this area has been in the use of newer visualization and mathematical techniques to improve the on-line, real-time operational performance of power systems.
Summary details on each of these projects is provided in this chapter. Further details on the Group's research activities are presented in the Electric Energy Industrial Consortium's Annual Report.
Sponsor: National Science Foundation
Abstract: The PYIA provides long-term funding to pursue research in a general area, with matching funds to encourage industrial involvement. The area for this award is power system operations, the most dynamic and significant area of power engineering. Utility operation is being increasingly dominated by the transfer of large blocks of energy over long distances and by numerous smaller transfers from independent power producers. A virtual moratorium on construction of new generation and transmission facilities has resulted in a shift in the responsibility for the safe, reliable, and economic supply of electric energy from construction and planning to operation. This shift has caused a surprisingly rapid and widespread acceptance of digital computers and computational tools throughout the utility industry. The tools themselves have been in existence for many years, but usually in an off-line form. On-line use and changing operating conditions impose new requirements that need research to fully understand and satisfy.
Specific efforts supported by this grant are validating the area of Power System Visualization, that is, showing the numerical results from analytical tools in graphical form, User-Centered Emergency Control, in which the analytical algorithms computing emergency control actions are designed with the power system operator's needs in mind, and Simulation of Load-Frequency Control in a Deregulated Environment.
Sponsor: NSF, Engineering Coalition of Schools for Excellence in Education and Leadership
Abstract: Students and engineers view circuits through a very restricted medium, either computed voltages and currents, or the instruments available to detect them. Because it is difficult to look at more than a few measurements at any one time, and because these often appear as abstract numbers, the development of qualitative understanding of circuit operation is difficult, in comparison to understanding, say, the operation of a set of gears, or the structure of a bridge.
This project is to write and test a circuit simulation program, similar to SPICE but less sophisticated analytically, that creates visualizations-graphical representations-showing simultaneously all of the voltages and currents in pedagogical circuits, those found in introductory circuit theory courses. The visualizations may help to communicate circuit behavior to students in an intuitive way, lowering the cognitive barrier to comprehension of circuit operation which is a factor in discouraging some otherwise qualified students from pursuing electrical engineering.
The program development has followed the syllabus of our first circuit theory course and now includes the visualization of DC resistive circuits in steady state, linear controlled sources, op amp circuits, transient visualization of RLC circuits (switch closure problems), and, most recently, AC steady state circuits. The next phase will be testing of the effectiveness of the program. Some initial testing has been performed, with promising results.
Sponsor: Snohomish Public Utilities District No. 1
Abstract: The reliability of current distribution systems is hard to quantize from the customer's point of view. Further, the reliability evaluation methods currently in use consider only prolonged outages, while customers regard momentary outages and power quality problems (voltage sags, spikes, harmonics, etc.) as indications of unreliable service. Lastly, the ability to translate from reliability to dollars when making design decisions for distribution systems is presently very poorly developed. The objective of this project is to address these problems by proposing new ways of measuring reliability that take into account the power quality and economic aspects, and to build a computer program capable of predicting the expected reliability of any given distribution system design.
Building on a successful implementation of reliability assessment using Markov Modeling and reliability network reduction, the present phase of the project includes addition of a graphical front end, modeling of windstorm related outages using Monte Carlo methods, estimation of component failure rate values from historical reliability data, and addition of a capability for cost/reliability comparison of competing designs (switch and protection placement).
Sponsor: National Science Foundation
Abstract: In this research, we have developed a new theory for the complete controllability of power systems. Within a complete controllability region, the power system can be steered from a state to any other state with the available controls. We analyzed complete controllability based on N-bus nonlinear, dynamic power system models. The major results are (1) local controllability criteria, (2) construction of complete controllability region for unbounded controls using the foliation theory, (3) properties of the complete controllability region, (4) characterization of the complete controllability region for bounded controls, and (5) computation of the complete controllability regions for simple power system models.
Future work in this research includes the development of techniques for decomposition of the nonlinear dynamic mechanisms and handling of uncertainties for controllability in a less-regulated power industry environment.
Figure 1.An n-bus power system model.
Figure 2.A complete controllability region with bounded controls.
Sponsors: Electric Power Research Institute and Puget Sound Power and Light Co.
Abstract: An Advanced Alarm Processor (AAP) has been developed in this research project. The AAP is a model-based reasoning system that incorporates transformers, communication systems, and the power network in its model base. A unique feature of the AAP is a power flow relation model that provides knowledge on the relations linking network variables (e.g., voltages and power flows) with the status changes. The AAP prototype was demonstrated at the EPRI Workshop on Advanced Alarm Processing organized by the University of Washington.
Future work includes the development of a power system protection module that can be used to analyze alarms resulting from operations of the protective devices. A methodology for integration of the AAP modules will be developed.
Sponsor: Automation Research Center, ENEL, Italy
Abstract: The ability to locate faults or malfunctioning devices depend on the availability of data and information. In a typical energy management system in the U.S., relay or SER information is not available on-line. As a result, the fault diagnosis capability is quite limited. Relay operations can help identify the power system components that may be faulted. To achieve pinpoint accuracy, however, the SER information with a precision level within milli seconds is essential. In this project, we have selected the SER information that can be used to pinpoint the fault location(s) and malfunctioning device(s). This logic-based system is implemented in an object-oriented software environment.
The IAA prototype resulting from the Phase I research has been demonstrated at the National Control Center of Italy in Rome. In Phase II, the tasks to be performed include network status processing, SER data preprocessing, thorough testing and functionality enhancement, computational performance enhancement, and development of the ability to handles multiple hypotheses.
Sponsor: National Science Foundation Graduate Fellowship awarded to Gary Rosenwald
Abstract: Energy transactions between electric power companies are commonly used to reduce operating costs. With movement toward a less-regulated power industry, the number and importance of contracts are expected to increase. In this research we developed a new method to quickly and systematically evaluate potential contracts. A fundamental concern of contract analysis is whether or not the contract is feasible, i.e., if the terms of the contracts can be met without violating system operating constraints or prior contractual constraints. The novel features of our approach are a model of the essential components of a contract using rules and a contract consistency checking algorithm based on rule inference techniques. Our future work includes the development of contract decision making methodologies.
Sponsor: Southern California Edison Company, Bonneville Power Administration
Abstract: Switching transients occurring in power systems are often due to circuit breaker (CB) switching. CBs are not designed to close or open at the time of minimum stress (zero voltage for closing and zero current for opening). For example, when a circuit breaker switches a capacitor bank, large and damaging voltage and current transients may occur. Depending on the switching instance, the bus voltage may collapse momentarily to zero then oscillate at high frequencies with high magnitudes. When the circuit breaker of a capacitor bank opens, an arc is often produced which causes transients in current and voltage. To avoid these transients, CBs should ideally be closed at zero voltage and opened at zero current. This is achievable by the Adaptive Sequential Controller (ASC) developed in the Energy Laboratory of the University of Washington. The ASC has the following general features:
1. Its power electronic circuit allows each phase of a circuit breaker to close at or near zero voltage. The controller can be programmed to trigger the magnetic mechanism at a precise time, taking into account the speed of the breaker's operating mechanism. The triggering circuit is activated so that when the circuit breaker contacts close, the voltage across the breaker is at or near zero.
2. The same operating principal is used to open the CB at the point of minimum stress.
3. When the breaker speed drifts due to weather or normal wear, the ASC automatically compensates for the change without human intervention.
4. The ASC is "Safe-fail." If the ASC fails, it will automatically disconnect from the circuit breaker operating mechanism so that the breaker can operate manually or remotely in a non-sequential manner. The ASC can be used with any single pole breaker, or modern multi-phase breakers with independent phase magnetic operating mechanisms (solenoids). For multi-phase, mechanically-ganged breakers, where only one solenoid is employed, the ASC could be used after additional operating mechanisms are retrofitted to the other phases. At this stage of development, the ASC is not designed to operate as described during faults. Fault interruption will be done by the normal fault clearing mechanism of the circuit breaker.
http://http://cialab.ee.washington.edu
Sponsor: National Science Foundation and Electric Power Research Institute
Abstract: One of the most difficult problems in the operation of large synchronous turbine-generators is the detection of shorted turns in the DC-field of the rotor. Not only is the existence of a shorted turn in the field winding hard to detect, its correction may result in an expenditure of several hundred thousand dollars when including the cost of replacing the lost power generation with more expensive sources such as large nuclear powered machines. Unfortunately, this expense is incurred even in the case of a wrong diagnosis. This is because the major expense results from the disassembly and assembly of the machine and in the added cost of alternative production. Proper localization, and more important, accurate determination of the actual existence of a shorted-turn, is therefore essential to avoid huge unnecessary monetary losses. A general solution to this problem has so far remained elusive. In this project a twin signal signature sensing is used to monitor, detect, and localize shorts in power system equipment with windings, including rotors, transformers, motors and large synchronous turbine-generators. There has, to date, been no effective way to do so. The most obvious approach, time domain reflectometry, fails due to the reactive coupling in the windings. Twin signal signature sensing of shorts results from identical signals being simultaneously injected in both sides of the windings. The transmitted signals are differenced to obtain the signature signal of the device. Through the monitoring of the evolution of the signature signals, development of winding shorts can be diagnosed through the process of novelty detection. Windings with shorts previously fingerprinted can be subjected to tests to localize the shorts. The standard layered perceptron neural network appears ideal to make these decisions. Preliminary work, performed on both downed and rotating loaded rotors, has been quite promising in demonstrating the effectiveness of the twin signal signature sensing approach to winding short evolution monitoring.
http://http://cialab.ee.washington.edu
Sponsor: Southern California Edison Company
Abstract: High voltage breakers can eventually develop improper contact alignment. The initial result is typically a small ohmic voltage drop across the contacts. Left unattended the voltage drop can worsen, resulting in arcing and eventual breaker failure. Detection of the contact resistance during the circuit breaker closure will facilitate an early corrective maintenance before a severe and costly damage occurs to the breaker. Feasibility of detection of the contact resistance early in the failure maturation, including laboratory demonstration of hardware prototype, is the objective of this investigation.
The Detection device operates while the breaker is at high voltage. The device detects a voltage drops of millivolts across milliohms at the breaker contact when closed. The accessibility of the device is only to the external terminals of the breakers and auxiliary contacts.
http://http://cialab.ee.washington.edu
Sponsor: Boeing Company
Abstract: Although the discipline has been around for quite some time, interest in the application of artificial neural networks has exploded in the last decade. Within three years, five new journals dedicated only to artificial neural networks appeared. A number of international conferences have attracted thousands of participants. Japan, Europe and the United States have each launched multi-million dollar research programs into the field of artificial neural networks and their applications. The reason for the excitement is the incredible potential computational abilities of the neural net and the ability of modern technology to implement the required neural net architectures. Neural networks have found use in numerous fields, including speech recognition, stock market forecasting, mortgage brokering, and remote sensing. Since the neural net is amenable to learning inherently nonlinear and/or complex relationships from examples, a number of system problems are potentially applicable to neural net solutions. Neural networks are especially suited for several electrical system problems such as stability assessment, harmonic evaluation and detection, fault diagnosis, adaptive control, and alarm processing. The purpose of this research is to evaluate the Artificial Neural Network technology for aviation electrical systems. This includes electric drives control, fault detection of electrical equipment, and stability assessment.
http://http://cialab.ee.washington.edu
Sponsor: Puget Sound Power and Light Company and Tellus Corporation
Abstract: This project is aimed at automating distribution system planning and operations. An intelligent decision support system, namely Automated Electric Plat Design (AEPD), is the primary achievement of this project. AEPD combines the functionality of a Geographic Information System (GIS) with the sophistication of Intelligent Systems (IS) to automate the underground distribution system design for a residential development. AEPD provides utility planners with an efficient tool that helps visualize the design solutions and costs at the same time. In addition, AEPD also supports a set of engineering analysis and optimization tools that would facilitate what-if analyses in the decision-making process. The following figure shows an automated electric plat design. The success of AEPD development has inspired many new applications that require the spatial data model of a GIS in distribution system planning and operations. For example, a generic distribution planner has recently been devised using object-oriented modeling techniques, which is applicable to all levels of distribution planning. To improve the quality of the planning solution, this project develops a collaborative scheme that utilizes different optimization approaches, such as heuristic search algorithms and Genetic Algorithms. This project is currently implementing a prototype for GIS-SCADA integration upon which the trouble-call analysis and several other outage management applications will be developed.
An Automated Electric Plat Design