KUET Institutional Repository (Khulna University of Engineering & Technology)
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Design and Demonstration of Smartphone-Based Colorimeter
No full textThis thesis is submitted to the Department of Electrical and Electronic Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Master of Science in Electrical and Electronic Engineering, December 2019.Cataloged from PDF Version of Thesis.Includes bibliographical references (pages 82-88).In this thesis work, smartphone-based colorimeter is designed and practically implemented utilizing the in-built sensors like CMOS camera, flash LED, and high-power processor of the smartphone. The developed totally self-contained colorimeter is low-cost, light-weight, robust, field-portable and easily accessible. It has smart sensing facilities without the requirement of additional optics and external power supply. The device can be applied for real-time and on-site measurements of different types of analytes in the fields of environmental research, biomedical applications, and agriculture, which are completely absent in the currently used conventional bench-top type colorimetric instruments.
In the real-world, for most of the colorimetric detection, attributes of color such as wavelength, intensity, saturation, etc. vary simultaneously according to the variation of analytes. The conventional smartphone-based colorimeters are mainly designed to measure the analytes considering the change in color information in only one domain which limits the colorimetric measurement in some specific analytes with a narrow band of detection. In this research, the developed smartphone-based colorimeter can quantify any analytes through multiple nonlinear regression based colorimetric assessment in a wide range of detection considering the variation of color attributes in all significant domains.
To demonstrate the smartphone-based colorimeter a 3D optical enclosure is designed and fabricated for ensuring the constant illumination and hence to improve the SNR by isolating the measuring platform from the environmental illumination. Self-referencing is a unique characteristic of the instrument to calculate the color ratio with respect to the colorimetric information of the sample. A customized Android-based smartphone app is developed for the complete functioning of the developed colorimeter. The app is developed with the graphical user interfaces of calibration, assessment of the real-time or previously recorded test samples, save, and share the results of colorimetric measurement for multiple analytes of different colorimetric tests. For the first time, a novel wavelength estimation algorithm is developed to estimate the wavelength information of the reflected light of colorimetric measurement.
To justify the performance of the developed colorimeter, three different colorimetric tests are demonstrated in this research named as Rhodamine B concentration quantifier, digital pH meter, and chlorine concentration quantifier using the Xiaomi Redmi Note 4 smartphone. Three different colorimetric characteristics are found for the three samples: only color tone changes significantly with the variation of Rhodamine concentration, the wavelength of color varies significantly with the variation of pH value in water, and color intensity, wavelength, and saturation all vary simultaneously with the variation of chlorine concentration. For all of the three colorimetric tests, the performance of the designed smartphone-based colorimeter is found excellent compared to the conventional colorimeters. The average error of RhB concentration quantifier within the detection range of (0.2-4.0) PPM is 0.95% whereas the chlorine concentration quantifier shows an average error of 1.16% for the detection range of (0.1-8.0) PPM with sensitivity 0.1 PPM. On the other hand, the digital pH meter detects pH value in the range of (4.0-9.0) with an average of 0.0876% detection error.
It is noted that the present smartphone-based colorimeter is designed and demonstrated using three analytes but the developed device can be applied to measure any colorimetric analytes by proper calibration using the developed smartphone app. So, the developed martphonebased colorimeter could be a cost effective common platform for the colorimetric measurement of various analytes in different fields of applications.Saptami RaniMaster of Science in Electrical and Electronic Engineerin
Model Predictive based Energy Efficient Control of an On-Grid PV Inverter
No full textThis thesis is submitted to the Department of Electrical and Electronic Engineering, Khulna University of Engineering & Technology in partial fulfillment of the requirements for the degree of Masters of Science in Electrical and Electronic Engineering, March 2019.Cataloged from PDF Version of Thesis.Includes bibliographical references.Renewable energy is now one of the most interesting topics in the field of distributed energy
generation. Among the renewable energy sources, the solar photovoltaic (PV) source has become the most popular and effective one. Generally, PV system is connected to an ac grid through an inverter. The inverter should be controlled in such a way that it can penetrate maximum power to the grid. However, designing a controller for the inverter is a difficult task due to the intermittent PV source. The traditional pulse width modulation (PWM) based inverters produce high total harmonic distortion (THD) in the output current. This causes a significant amount of power loss and thus less power penetration to the grid. It makes the on-grid PV systems inefficient. Therefore, model predictive control (MPC) based energy efficient conversion of PV power is proposed in this research work. In the proposed MPC, the control objectives (current and switching frequency) are predicted using a finite number of voltage vectors produced by the inverter. MPC selects an optimal control action (i.e. switching state) in every sampling instant for the inverter by minimizing a predefined cost function. The cost function includes current tracking error and number of switching transitions. These two control objectives are combined in the cost function with a weighting factor. The first control objective provides a smooth current tracking accuracy, which increases the r.m.s amplitude of the injected current and thus increases the power penetration to the grid. The second control objective reduces the average switching frequency, which actually reduces the switching loss. The value of weighting factor in the cost function is selected by making a tradeoff between the current THD and the average switching frequency. Simulation results show that the proposed controller tracks the reference current accurately with mean absolute error of 2.5% which is 30% for the PWM based controllers. The low current tracking error for MPC based inverter yields low current THD of 2.07%, whereas in
traditional PWM based inverter the current THD is 7.26%. As a result, the proposed MPC based inverter penetrates 12.8% more active power to the grid than the PWM based inverter. The active power penetration is confirmed by load flow analysis using IEEE 13 bus test feeder. The energy efficient operation of the MPC based inverter is also verified by doing loss analysis. There are three types of loss considered in the research work: conduction, switching and harmonic losses. The conduction, switching, and harmonic losses of the inverter are reduced by 36.8%, 50%, and 91.9%, respectively, in comparison with the PWM control based inverter. The performance of the proposed controller is also analysed in terms of transient response, decoupling control, and fault tolerant ability. It is shown that the proposed MPC yields decoupled current control and fast transient response, and capable of handling the symmetrical and unsymmetrical faults in the grid. The research outcome from this comprehensive analysis proves that the proposed controller reduces the power loss to maximize the penetrated power and ensures the performance of the proposed controller as an energy efficient controller for an on-grid PV inverter.Amit Kumer PodderMasters of Science in Electrical and Electronic Engineerin
