Leonard J. Bohmann

Power engineering design projects: capstone team projects versus topical design courses

Over the years, Michigan Tech has had two different philosophies for teaching design in the power area. Initially, we integrated design into topical courses, teaching the material the students would need to complete the design. Presently, our students complete year-long, industry-sponsored projects. We will give details on the implementation of the two approaches and compare and contrast the outcomes. Both techniques for teaching design have their advantages and disadvantages.

A VARIABLE VOLTAGE AND FREQUENCY SCHEME TO OPTIMIZE THE EFFICIENCY OF A WIND-DRIVEN INDUCTION GENERATOR

ABSTRACT The most recent approaches to harness energy from the wind utilizing induction generators has been made possible by advances in induction motor control using power electronic drives. The freedom in adjusting terminal voltage or current, and frequency al lows operation of the induction machine to fit any desired characteristic. The purpose of this paper is to propose a scheme using this technology to convert wind energy to electricity at maximum wind turbine power and induction generator efficiency. The Electromagnetic Transients Program (EMTP) is used to simulate the control of the induction generator. Simulation results show that this system operates as predicted in a stable fashion at the desired operating point.

Detection of coherent groups of generators and the need for system separation using synchrophasor data

Detection of groups of coherent generators is very important for balanced and optimal power system separation. Synchrophasor technology has made it possible to get the real time phasors i-e voltage and current along with the frequency. This real time information can be used to find groups of coherent generators. Hierarchical clustering algorithm is used on the rate of change of the generator bus voltage phase angles and rate of change of mean of the generator bus voltage phase angles are tested for the purpose of detection of groups of coherent generators. Initial results show that these approaches can be used for the purpose of real time detection of the groups of coherent generators.

Defining a Curriculum for Service Systems Engineering

The U.S. economy has gradually changed from one based in agriculture, to one focused on manufacturing, to one now that relies heavily on the service sector. The service sector, including governmental agencies, retail stores, the entertainment business, public utilities, and providers of similar services, now makes up more than 80% of the total U.S. economy. Engineering programs, which typically have their roots in the era of manufacturing, have a focus on the design and fabrication of “products” rather than the design and creation of service systems. While curricula such as engineering management and industrial engineering provide some support to service systems engineering, their legacies are tied to the manufacturing sector, and as a result, they are not optimized to support the service sector. With this in mind, a Delphi Study was performed to identify the features, characteristics, and topics relevant to a service systems engineering curriculum. This paper describes the planning, conduct, and results of the service systems Delphi Study and how this information is being used to establish a new engineering degree program at Michigan Tech.1

The new energy systems course at Michigan Tech

Michigan Tech (USA) is now at the end of a development cycle for a new course in energy systems. Here, the authors describe how, over the past 2 1/2 years, they have been working with the support of the National Science Foundation and the Electric Power Research Institute to develop an introductory course in energy systems which is stimulating for the students, is up to date, gives a broad understanding of the field, and which lays a solid foundation for future study.

The development of a new core electrical engineering course in energy processing systems: a work in progress

The National Science Foundation and the Electric Power Research Institute have awarded six grants to seven universities as part of the Innovations in Electric Power Education Initiative. As part of this initiative, the authors are developing a new introductory course in energy processing systems that they hope will be a model for other universities to adopt. The course looks at all aspects of electric energy production, transmission and distribution and utilization. It introduces technical concepts as well as explains business, economic, regulatory, environmental and historical issues. The authors attempt to give the students the big picture, how electric energy affects their lives and the world around them. The idea is to create a course which all electrical engineers will find relevant, and thus EE departments throughout the USA can be justified in using all or part of the material they develop for a required course in electric energy.

BACK-TO-BACK CAPACITOR ENERGIZATION TRANSIENTS MITIGATION: COMPARISON OF PRE-INSERTION INDUCTORS VERSUS SURGE REACTORS ON A 46 kV SUBTRANSMISSION SYSTEM

ABSTRACT Two devices that are used to reduce back-to-back capacitor bank energization transients, pre-insertion inductors and surge reactors, are investigated in this paper. The Alternative Transients Program (ATP) was used to develop a computer model of a 46-kV system. A parametric study, varying the switched capacitor size and the system strength, was completed to determine the effectiveness of the two methods. Pre-insertion inductors reduced the peak inrush current better than the surge reactors. However, both of these devices generated peak overvoltages greater than the case containing neither of them. The optimum inductor size is highly system dependent. A thorough study of the system should be completed before the choice is made to use pre-insertion inductors or surge reactors.

Small signal transient stability of periodically switched circuits

A method of small signal analysis for a class of switching circuits is presented and is demonstrated using a single phase bridge rectifier circuit. This method may be used in any switching circuit in which the switching is periodic. The state equations for the circuit are written and shown to be a set of linear differential equations with periodic coefficients. The periodic transition matrix is determined and the characteristic roots of this system are shown to determine the transients around a steady state operating point.

Wind Plant Interaction in a 345-kV Series-compensated Power System—Electromagnetic Transient Program Modeling and Event Analysis

Abstract Application of series capacitors on high voltage transmission lines has recently been gaining attention due to sub-synchronous interaction concerns with wind turbines based on doubly fed induction generators. However, most reported analysis is based on single-machine representation of the wind plant. While this approach is convenient for eigenvalue analysis and frequency scanning studies, the effect of ignoring the collection system and multiple wind turbines will result in current oscillations that may not capture all interacting frequencies. This article presents the investigation of a wind plant interaction event observed in a practical 345-kV series-compensated power system along with the development of a full-scale Electromagnetic Transient Program model. Multiple interaction frequencies in three distinct frequency ranges with low damping was identified in both Electromagnetic Transient Program simulations and event records. This demonstrates the need for full-scale Electromagnetic Transient Program models when designing sub-synchronous protection schemes and testing of sub-synchronous interaction damping controllers. Discrete Fourier transform and Prony analysis have been used for analysis of frequency and damping content in the resulting current oscillations. The Alternative Transients Program version of the Electromagnetic Transient Program was used to perform the time-domain simulations.

Recovery Act - An Interdisciplinary Program for Education and Outreach in Transportation Electrification

1) How the project adds to the education of engineering students in the area of vehicle electrification: This project created and implemented a significant interdisciplinary curriculum in HEV engineering that includes courses focused on the major components (engines, battery cells, e‐machines, and power electronics). The new curriculum, rather uniquely, features two new classes and two new labs that emphasize a vehicle level integration of a hybrid electric powertrain that parallels the vehicle development process used by the OEMs ‐ commercial grade software is used to design a hybrid electric vehicle, hardware‐in‐the‐loop testing is performed on each component until the entire powertrain is optimized, the calibration is flashed to a vehicle, ride‐and‐drives are executed including on board data acquisition. In addition, nine existing courses were modified by adding HEV material to the courses. 2) The educational effectiveness and economic feasibility of the new curriculum: The new courses are offered at both the undergraduate and graduate levels. They are listed across the college in mechanical, chemical, electrical, and materials science and engineering. They are offered both on campus and to distance learning students. Students across the college of engineering and at all degree levels are integrating these courses into their degree programs. Over the three year project the course enrollments on‐campus has totaled 1,249. The distance learning enrollments has totaled 315. With such robust enrollments we absolutely expect that these courses will be in the curriculum for the long run. 3) How the project is otherwise of benefit to the public: One outcome of the project is the construction of the Michigan Tech Mobile Lab. Two complete HEV dynamometer test cells, and four work stations are installed in the 16.2 meter Mobile Laboratory and hauled by a class 8 truck. The Mobile Lab is used to teach the university courses. It is also used to deliver short courses to industry, K‐12 outreach, and public education. In 2012 the Mobile Lab participated in 22 outreach events, locally, throughout Michigan, and including events in Washington DC, Illinois, and Wisconsin. The Mobile Lab is a hit wherever it goes. In 2013 we will partner with the US Army TARDEC and be featured in their Green Warrior Convoy, a ten city tour starting in Detroit and finishing in Washington DC.