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The time duration of this project was from April to September 2003. Background: 2. The alma of our project was to design & develop simulation software for Computer Aided distribution system design & analysis. To achieve this goal I had to study about power distribution system design & analysis in depth, I had to read recent journals and publications to know the latest improvement and invention in this field. I also take help from the Internet to collect information.
In my project I acquire impressive knowledge on the technology used in the existing methodology of load-flow studies. With my team met I was Involved In problem definition, mathematical formulation of the equation of load-flow studies Involved in distribution system design & analysis, and In software design. I visited the practical site where of Bangladesh Rural Electrification board where this technology can be implemented, to observe how they are working, what are the common problems they are facing and what they are thinking about should be done in this sector.
I also met the decision maker in this sector to know about the future plan. Another point, at the mime duration of the project work my selected site was not under digital design system. For these reason the work also had a different aspect to think apart from the technological view, the economic and financial aspect also. 3. The need for computational aids in power system engineering led In 1929 to the design of a special-purpose analog computer called AU AC network analyzer.
By the middle asses network analyzers were in operation In the United States and Canada and were Indispensable tools to planning, relaying, and operating engineers. The earnest application of dealt computers to power system problems dates back to the ate asses. However, most of the early applications were limited in scope because of the small capacity of the punched card calculators generally in use at that time. In 1957 the American Electric Power Service Corporation completed a large-scale load- flow program for the IBM 704 which calculated the voltages and power flows for a specified power system network. Roved so successful that all subsequent studies employed the digital computer instead of the network analyzer. The success of this program led to the development of programs for short circuit and transient stability calculations. Today the computer is an indispensable tool in all phases of power system planning, design, and operation. 5. The great technical advances in the design and production of commercial and scientific general-purpose digital computers since the early asses have placed a powerful tool at the disposal of the engineering profession.
This advancement has made economically feasible the utilization of digital computers for routine calculations encountered in everyday engineering work. In addition, it has provided the capability for performing more advanced engineering and scientific computations hat were previously impossible because of their complex or time-consuming nature. 6. The development of computer technology has provided the following advantages to power system engineering: a. More efficient and economic means of performing routine engineering calculations required in the planning, design, and operation if a power system. . A better utilization of engineering talent by relieving the engineer from tedious hand calculations and permitting him to spend more time on technical work. C. The ability to perform more effective engineering studies by applying calculating reoccurred to obtain a number of alternate solutions for a particular problem to provide a broad base for engineering decisions. D. The capability of performing studies which heretofore were not possible because of the volume of calculations involved. 7.
Two major factors which have contributed to the realization of these benefits are the declining cost of computing equipment and the development of efficient computational techniques. Now that a substantial reduction in computing cost has been effected, principal effort must be directed toward the orientation of engineering problems to computer solutions. Personal workplace activity: 8. Computer analysis of power distribution system has necessitated a better understanding of the engineering and mathematical bases for problem solving by computer programming language.
The most important part of this simulation software development was Load studies of the system because satisfactory operation of the system depends on knowing the effects of interconnections with other power systems, of new loads, new generating stations, and new transmission lines before they are installed. Load-study is the determination of the voltage, current, power, and r contemplated conditions of normal operation. The principal information obtained from a load-flow study is the magnitude and angle of the voltage at each bus and the real and reactive power flowing in each line. . I implemented the load-flow studies by using famous engineering equation of solving linear algebraic equations in an iterative manner known as the Gauss-Sidle method. The process of applying a computer to the solution of engineering problems involves a number of distinct steps. I had to follow the following steps: a. Problem definition: initially, the problem must be defined precisely and the objectives determined. This was the most difficult step in the entire process.
Consideration must be given to the pertinent data available for input, the scope of the problem and its limitations, the desired results, and their relative importance in making an engineering decision. This phase requires the Judgment of experienced and capable engineers. B. Mathematical Model formulation: After the problem has been defined, it is necessary to develop a mathematical model to represent the physical system. This requires specifying the characteristics of individual system components as well as the relations which govern the interconnection of the elements.
A network matrix equation provides a convenient mathematical model for a digital computer solution. The elements of a network matrix depend on the selection of the independent variables, which can be either currents or voltages. Correspondingly, the elements of the network matrix will be impedances or admittances. The electrical characteristics of the individual network components can be presented conveniently in the form of a primitive network matrix. This matrix, while adequately describing the characteristics of each component, does not provide any information pertaining to the net-work injections.
It is necessary, therefore, to transform the primitive network matrix into a network matrix that describes the performance of the interconnected network. The form of the network matrix used in the performance equation depends on the frame of reference, namely, bus or loop. In the bus frame of reference the variables are the nodal voltages and nodal currents. In the loop frame of reference the variables are loop voltages and loop currents. The formation of the appropriate network matrix is an integral part of a digital computer program for the solution of power system robbers.
A network is made up of an interconnected set of elements. In the bus frame of reference, the performance of an interconnected network is described by n-l independent nodal equations, where n is the number of nodes. In matrix notation, the performance equation in impedance form is where BUS= vector of BUS voltage measured with respect to the reference BUS I-BILLS = vector of impressed BUS current ZEBUS = BUS impedance matrix whose elements are open circuit driving points and transfer impedances.
The solution of the load flow problem is initiated by assuming latest for all buses except the slack bus, where the voltage is specified and remains fixed. Then, currents are calculated for all buses except the slack bus from the bus loading equations involves mathematical expressions, such as sets of nonlinear equations, differential equations, and trigonometric functions, which cannot be evaluated directly by a digital computer. A computer is capable of performing only the four basic arithmetic operations of addition, subtraction, multiplication, and division.
A solution for any problem, therefore, must be obtained by numerical techniques which employ the our basic arithmetic operations. It is important in this phase to select a method which is practical for machine computation and, in particular, villa produce the desired results in a reasonable amount of computer time. Since numerical approaches involve a number of assumptions. Careful consideration must be given to the degree of accuracy required.
Digital solutions of the load-flow problems we shall consider follow an iterative process assigning estimated values to the unknown bus voltages and calculating a new value for each bus voltage from the estimated values at the other buses and the real and reactive power specified. A new set of values for voltage is thus obtained for each bus and used to calculate still another set of bus voltages. Each calculation of a new set of voltages is called iteration. The iterative process is repeated until the changes at each bus are less than a specified minimum value. D.
Program design: The sequence of logical steps by which a particular problem is to be solved, the allocation of memory, the access of data, and the assignment of input and output units are important aspects of computer program design. The objectives are primarily to develop a procedure which eliminates unnecessary repetitive ululations and remains within the capability of the computer. The program design is usually prepared in the form of a diagram called a flow chart. E. Programming: A digital computer has a series of instructions consisting of operation codes and addresses which it is able to interpret and execute.
In addition to the arithmetic and input/output instructions, logical instructions are available which are used to direct the sequence of calculations. The translation of the precise detailed steps to be performed in the solution of a problem into an organized list of computer instructions is the process of programming. A program can be developed by using computer instructions in actual or symbolic form, or it can be written in a generalized programming language. F. Program verification: There are many opportunities to introduce errors in the development of a complete computer program.
Therefore, a systematic series of checks must be performed to ensure the correctness of problem formulation, method of solution, and operation of the program. In developing CADS (Computer Aided Distribution System Analysis) Visual Basic programming language is used with Gauss- Sidle Method for mathematical formulation of load-flow studies and for database, MS access is used. 10. It took us three months to gather all the information and conduct all the well as motivate my teammates to work sincerely and effectively for the project.
During these months, we met a couple of times during weekdays and weekends to assist and assess each other in doing the project work. I used to identify the components of the total work and distribute tasks among us. I also had to prioritize the tasks to achieve best results. We also met our course conductor Dry. M Shameful Lam a few times during the project work to discuss our findings and get valuable suggestions. He helped us a lot by his guidelines about what to do and how to do.
Then we prepared the project report through effective discussions and submitted it to the faculty of Electrical & Electronic Engineering at Chitchatting University of Engineering & Technology, Bangladesh. We also made a presentation in front of our class and explained the Optical fiber technology and our findings from this investigative project clearly and concisely. There was a questions-answers session after the presentation, when we answered the questions from the audience to further clarify the different aspects of Computer Aided Power Distribution System. Software overview: 11.
Fig: Typical Single Line Diagram drawn by the simulation software Fig: Graphical output of voltage & current at each node Fig: Sample out put of loss curves for simulated section of a sample network operating from 10% to 150% of installed load. The total load curve shows that the system may carry an optimum load of 45% to 55% of the installed load Summary: 12. Our developed software under this project CADS (Computer Aided Distribution System Analysis) is capable of performing voltage level study, loss calculation, and performance study by easy single line diagram drawing with an easy o use data entry features.
We hope if this software is used in power system analysis of BAD it will help better and precious analysis of Distribution System easily and in much less time then now. This software can also be used in simulation lab of engineering educational institutes in Bangladesh. This will help the undergraduate student to know about real distribution system analysis and how to do it. This software has the option to integrate on line data entry from the live power system. We appreciate further development of the project for full automation.
By completing this project successfully, I have learnt a lot about power distribution system design technologies and achieved a capability to think about future possible interpolation in this sector, which will contribute to my professional career in the future. My research on this new technology opened a new door for me to the power system-engineering world. I also acquired a better understanding of the R&D (Research and Development) process of a new technology. Overall, our project work was satisfactory and our project supervisor Dry. M. Shameful Lam appreciated it.