Figure 1. Layout of a typical laboratory workstation
MAJLESEIN, Hamid1, BHATTACHARYA, Pradeep2 & DABIPI, Ibibia3
329 J. B. Moore Hall, Department of Electrical Engineering, Southern University, Baton Rouge, LA-70813, U.S.A.
1 hamid@engr.subr.edu
2 bhattach@engr.subr.edu
3 dabipi@engr.subr.edu
Abstract: As a result of the ever-increasing demand for smaller size, lighter weight and better performance power supplies for computer, telecommunication, military, aerospace and home-automation applications, interest in the power and control systems areas have been growing rapidly in the past decade. In view of these recent advances and the extensive demand for these fields, it is clear that the demand for power and control engineers will be significant for many years to come. Although many universities currently offer programs of study in power and control, the art of designing new power and control engineering courses and laboratories are lagging far behind the growing industry needs for skilled engineers with hands-on experience. In the State of Louisiana, there are only a couple of Universities out of about more than fifteen offering the courseware's for power, control systems and machines to undergraduate and graduate level. The Southern University undergraduate programs keep updating and modifying what is taught in individual course as required by industries such as Entergy Corp. etc. The Electrical Engineering Department at Southern University and A&M College has a strong foundation for teaching power and control systems to the undergraduate students to serve the engineering needs of the strong industry-based in Central Louisiana. The development of this laboratory will take advantage of Southern University connections with local industry, and the expertise of its faculty to establish a kind of laboratory that would be a model for institutions nationwide. A laboratory experience is an excellent way to reinforce the principles of power and control systems. This paper looks at the considerations associated with establishing a hardware/software laboratory for the teaching of power and control systems.
The power and control laboratory was established in 1996 with the help of SKM System Analysis, Inc., Allen-Bradley, and Intel Corp. They provided us with the Softwares, hardwares and PCs and helped in installation and verification of their programs. The laboratory is equipped with electronic equipment and softwares to perform computer simulation, prototype construction, testing and evaluation of power systems circuits. Major equipment includes Programmable Logic Control (PLC), Variable Speed Drive (VSD), Oscilloscope, Digital Multimeter (DMM), PCs, Printer and Power Tools Softwares such as: Hi_Wave, I*SIM, Captor, Dapper, MATLAB and PSpice. The high-wave engineering laboratory is to provide students with "hand-on" experience on the design and analysis of ac and dc machines and power system circuits. The laboratory will consist of both hardwares and softwares facilities in simulation and analysis of different creative and design problems. These problems typically solve parameters without additional equipment, high efficiency mode of operation and simulate non-standard ac - line conditions. Precision, computer-controlled ac and dc power test and measurement on all the typically chosen circuits are of importance in such laboratories.
Keywords: laboratory, power, control, hardware/software
The successful design, renovation or relocation of today's sophisticated laboratory environments requires a unique combination of knowledge and experience. After all, these are decisions that must produce not only a cost-effective solution, but also a safe working environment that meets laboratory needs for years to come. A software/hardware laboratory in power and control system is able to provide the students with a degree of confidence which lecture courses alone are unable to give. This paper looks at the issues associated with developing power and control systems teaching laboratory that maximizes the learning process. These issues can be divided into two categories: The resources necessary to maintain a good laboratory and the qualified faculty to teach the laboratory.
Let's face it. Most people don't redesign their laboratories or buy new laboratory equipment's everyday. That's why it's not unusual to worry about making the right decisions when it comes to planning, installing and servicing equipment's that meet the demanding requirements of today's laboratories. Laboratory maintenance keeps you and your staff safe, saves energy, saves money, prevents premature failure of your laboratory equipment's, insures you comply with government regulations. A typical laboratory workstation has shown in Figure 1.
Figure 1. Layout of a typical laboratory workstation
In control system design, we develop system models from data derived in the laboratory (or out in the field). It requires a mathematical model given in the form of a transfer function or state-space model, and we know that both models are equivalent in the sense that they convey the same input and output information. A mathematical model is needed for the control system designer to make progress. Many students become frustrated with textbook problems in which models just appear out of nowhere. The design process for a control system problem is shown in Figure 2. The MATLAB is the tool that is used in this laboratory.
Figure 2. Elements of the control system design process
In power systems design, the experiments are designed to be used with the software as well as the hardware. The software part includes the simulation programs such as power tools softwares by SKM system analysis, MATLAB, Pspice. The hardware portion, which includes PLC, variable DC speed drive, Lab-volt equipments, and etc., is designed to facilitate the simulation part and give the students more understanding of the experiment. The exercises are intended to give the students hand-on knowledge of different types of simulating and measuring instruments of electrical equipment. They will go through a series of step-by-step procedures for computing values of different types of power system problems. The design process for a power system problem is shown in Figure 3.
Figure 3. The design process for a power system problem
When it comes to the planning, purchasing, installation and servicing of laboratory equipment's only a good technician has the ability to provide the work with a full satisfaction guarantee. Thorough planning - reduces the margin for error, corporate focus on laboratory equipment's not peripheral products, wide selection of world-class products. The technicians are required to have an adequate training in everyday technology as a way to minimize the cost of expert services while maintaining high degree of excellence in the laboratory. Using students along with the laboratory to advance hand-on experience in areas where students confidence in understanding can be enhanced.
With a basic understanding of lecture, students have a tool for independent discovery of more advanced topics and can experience the real life problem in all practical engineering problem solving. To create a foundation for and facilitate this discovery, the faculty should provide significant guidance for the basic laboratory problems, so that the students feel empowered and open-ended and encourage students to experiment with ways to improve their solution techniques.
Since students can significantly differ in the educational methods that work best for them, we need to present the problem in many different ways within each laboratory assignment. Each assignment should include goals and specific learning objectives, a discussion of the application context, a review of the basic mathematics needed in the assignment, as well as specific statements of the individual problems and directive questions to help students focus their efforts in productive directions.
Coordinating a laboratory with a course, to ensure that laboratories have maximal benefit, is an ongoing challenge. Students need to have enough knowledge to begin and complete laboratory assignments but also need to have laboratory assignments not lag so far behind the class topics that either more interesting or advanced topics that would benefit from reinforcement with laboratory instruction are not addressed. Combination of hardware/software that minimize cost is required. Knowledge of the person making the decision is also critical. Understanding student needs and faculty capabilities for a maximum learning environment. Group homeworks and learning from theory courses to apply in practical situations of the laboratory by programming new model and simulations are some of the best methods to bring coursework integration. Special application experiments by reengineering some useful gadgets are indeed very inspiring special projects. Students use such lessons to see how group work is done and how team evaluations are made on objectives achieved in the project. Theoretical questions tackled in increasing the efficiency of a gadget by reengineering methods are therefore contsructive exercise in integration of the laboratory experience to real life problems.
In any laboratory setting, preparation is critical for making consistent progress. There should be some laboratory preparations problems that ask the students to answer some simple questions based on the laboratory background material. These questions typically fall into two categories: simple examples to be worked out by hand, illustrating the basic idea that will be implemented in an application context in the laboratory, and formation of the problem, including computation of initial design parameters. The first type of question helps students to evaluate whether or not the results generated by their power or control tools simulation make sense and gives them an understanding of relevant calculations. Such calculations are the key to any practicing engineer's success in evaluating the potential of design alternatives with minimal effort and cost. The second type of question is intended to get students to prepare in advance for the actual laboratory work. This skill is valuable in engineering practice, as laboratory time is typically shared and costly. For the more difficult laboratory preparation problems, the student must have to collaborate in-groups to solve the laboratory preparation problems during a recitation section prior to the laboratory period. It is found that this approach, integrating group problem solving with laboratory assignments, helps to enhance the laboratory learning experience by allowing students to focus on the theoretical aspects prior to coming to laboratory.
Clear and effective safety procedures are to be developed and included in the description of each laboratory exercise. These procedures must be consistent with the relevant regulatory requirements for the discipline in question. Each faculty member teaching a laboratory must demonstrate familiarity with these procedures prior to teaching the laboratory. Of all the rules concerning safety, thinking is probably the most important. No amount of safeguarding a piece of equipment can protect a person as well as the person taking time to think before acting. Do not depend on circuit breakers, fuses, or someone else to open a circuit. Test it for yourself before you touch it.
Each laboratory assignment should have the format below:
Describes the overall goal of the laboratory in the application context. Typically the students should reread this statement of purpose after completing the laboratory to evaluate if this goal was achieved and to include this evaluation in their laboratory report.
Describes specific functional tasks that students should be able to perform by the end of the laboratory assignment. Typically these are not expressed in terms of the specific application, but rather as general intellectual competencies and laboratory skills.
Provides a list of topical references to concept addresses in the laboratory, with additional bibliographic references for applications, if needed. Topical should be separated into review and exploratory topics.
Problems to be completed before the laboratory session. As described above, attempting to answer these questions enables students to clarify any questions they might have and to make more effective use of laboratory time. It is found that physically placing these problems prior to the background reading is very effective for helping students to focus their reading and extract critical information from it.
This section provides a brief overview of the application and concepts needed in the laboratory assignment. The review of concepts is focused on the application context, in an attempt to bring students to the point where they should be able to begin the assignment, and is not meant as a substitute for classroom or textbook instruction.
Statements of problems to be solved in the laboratory. For each problem, there is an in-depth problem statement and directive questions to help students focus on what they are trying to achieve.
There is a strong connection between the laboratory and the lecture. A strong effort must be made to use the laboratory as a practical medium for reinforcing principles taught in lecture. Students are expected to demonstrate a clear understanding of how power and control instruments work. Revision of the laboratory format to include the demonstration of critical thinking must be recommended as well as maintenance of an ongoing record of laboratory activities in the form of notebook. Great coordination of subject matter and personnel for implementing effective laboratory course. Simulation software should always be used to reinforce concepts already introduced in the lecture. Each laboratory must develop and implement specific measures to ensure the proper operations of equipment's, proper training of laboratory technicians can also help ensure compliance and safety.