Essay, Pages 5 (1157 words)
This course dealt with the basics of power electronic devices, how they operate when used in both electrical and electronic circuits. Throughout the course work I came to an understanding of how power electronics is a core component in combining any two fields.
The main emphasis was on switched mode blocks and converters (rectifiers and inverters). The weekly assignments and quizzes challenged me and gave the opportunity to apply the knowledge I gained during the lectures. Pulse width modulation was one of the main emphasis in all the quizzes where I used PSCAD as the software to simulate and arrive at a solution.
Here is an example of how I calculated the peak ripple current of an inverter operating in synchronous PWM mode.
In addition to in class coaching I had an opportunity to participate in hands on training in the lab where I leant the characteristics of buck converters by changing the duty cycle and switching the frequency to determine input/output voltages and efficiency.
These experiments familiarized me with Oscilloscopes and some power electronic components. This experiment intrigued me to perform efficiency calculations on buck-boost converter as well. Over all the course structure was well designed to create a complete rainbow of electronics in the field of power.
Being interested in power electronics and the urge to gain more knowledge in the same field is one of the reasons for choosing this course. This course mainly dealt with dc generators, dq frame modelling, synchronous machines and its application in real time.
The weekly assignments helped me improve and learn simulation of complex circuitry in Matlab/Simulink. This eventually trained me to perform with utmost ease on my final project which was based on Induction motor.
Electrical drives play a pivotal role as it is a fundamental basis to convert mechanical to electrical and vice versa. Drives including inverters, rectifiers and other electronic devices generate waveforms as an output. Understanding waveforms has always been a challenge but using Simulink and analyzing multiple scenarios throughout the course work made it easy.
Project: Speed Control of Squirrel Cage Induction Motor using V/f control
The main objective of this project is to obtain to obtain a wide operating range of induction motor by maintaining the V/f ratio constant using PWM inverters. With the help of MATLAB, I was able to model a closed loop V/f control on a PWM inverter fed 3- phase induction motor.
In this course I gained knowledge of how electrical distribution system is laid out and the characteristics that are taken into consideration for the system. I understood the importance of various switching schemes implemented in modelling/designing of distribution-substations and their advantages/disadvantages.
This course emphasized the need of protection for the planned distribution system. Protection is a salient feature as the equipment used in the substations are of high cost and maintenance. This can be attained by having different types of bus configurations.
Project: Design a 69kV Substation from an existing one and include overhead and underground feeders. The aim of the project was to design a new substation by using a part of the one which is already existing. The first step was to design the substation using the one-line diagram as shown using a given reference. Apart from the design, the switches and their normal (NC or NO) operating conditions are also shown.
The next step was to design the feeders (overhead and underground feeders) including the main feeder and any sectional devices.
I was able to draw these schematics using AutoCAD Electrical. The equipment specifications are as follows:
- BKR1 – Manufacturer: Siemens Energy INC.
- Circuit Breaker, Outdoor type, Dead Tank, HV, 72.5(69) kV, 3000A, 40kA Interrupting capability, 350 BIL Composite Bushings, 120/240 VAC, 3 Pole, 125 VDC control voltage, w/o SF6 Fill Gas.
- Transformer – Manufacturer: ABB Model: Power Transformer
- HV Winding Voltage 69kV, LV Winding Voltage 13.2kV
- HV Winding connection Delta, LV winding connection Grounded WYE.
- CKTSW – Manufacturer: S&C Electric
- INTERRUPTER, CIRCUIT SWITCH Model 2030, 125VDC 69KV, 1200A
- Disconnect switch 69kV – Manufacturer: Southern States
- Model Series 2000, SF6 gas filled interrupters.
- Disconnect Switch 13.2kV – Manufacturer: Siemens Energy INC.
- Energy Delivery Systems (EEL 6285)
- Instructor: Prof. Zhixin (Lee) Miao
This course to a large extent dealt with the generator modelling, voltage source converters and dq frame modelling. The concepts of power electronics formed the basis for integrating the distribution systems including the microgrids. Also acquired the knowledge on reactive power controllers (current controlled and voltage controlled), deriving its dynamic models and converting from abc to dq frame. During power transmission is will always be power loss, hence compensators are used. The latter part of the course mainly focused on voltage source converts in various modes and its operation and how to model a synchronous machine.
All in all, with the weekly simulation assignments and labs conducted, a better understanding of the above was achieved. The simulation tool used was MATLAB. With every assignment, I was able to not only improve my simulation skills but also gained a clear understanding of a synchronous machine can be designed.
Here is an example of one such simulation wherein we had to design a frequency controlled VSC system for a given load and time. The frequency had to maintained constant and so, the load was constantly varied using gains, transfer functions and compensators. The clock signals were used to set the time period.
- Vabc and Iabc waveforms
- Math Course
- Linear and Matrix Algebra (EEL 6935)
- Instructor: Prof. Timothy J. Fawcett
Linear algebra helps you understand how the solutions to linear systems can be obtained using matrices and vectors. The different linear combinations of these vectors can be used to span a line or plane in a vector space. The basic properties of matrices such as matrix addition, subtraction, multiplication and Gauss-Jordan approach and LU decomposition were used to determine the complete solution of a linear system given. The concept of subspaces was introduced wherein the rank of a matrix is used to determine the dimensions and basis. The various linear combinations of the vectors can be decomposed into its components using the orthogonality of these vector spaces. This course also covered the theory of eigen values, special matrices, pseudo inverse matrices to name a few.
These can be summed up using the following example:
- Random Process in Electrical Engineering (EEL 6542)
- Instructor: Prof. Ismail Uysal
Random processes studies majorly the noise signals generated during a communication process. Easy understanding of this can be achieved by studying the concept of probability and statistic regularity. Bayes theorem and Bernoulli’s trails formed the basis for conditional probability. These consists of random variables which can be either discrete or continuous. Poisson and Gaussian random variables are two such variables of immense importance. Random processes is a set of random variables for which we can derive the correlation, expected value, variance. It stressed on the topic of two functions of two random variables and how it distributed in a space.