http://localhost:8081/jspui/handle/123456789/8 Mon, 02 Nov 2026 22:14:07 GMT 2026-11-02T22:14:07Z http://localhost:8081/jspui/handle/123456789/21762 Title: FAILURE ANALYSIS OF WINDING JOINTS IN DISTRIBUTION TRANSFORMERS Authors: Gupta, Shashank Abstract: Distribution Transformers (DTs) are the primary asset to any power distribution network. The failure of DTs has always been a concern for electrical utilities. The life of DTs is significantly affected by thermal stresses inside the transformer. The hot-spot formation is critical among various factors, especially in weak areas like winding joints. Over time, the contact resistance in winding joints tends to increase, potentially leading to a thermal runaway condition. A satisfactory winding joint should possess two characteristics; firstly, it should be able to pass the current without introducing an undesirable resistance into the circuit and secondly, it should continue to do so for a long time for better reliability. The winding joints in DTs show a high tendency to overheat during the operation and form a local hot-spot. The heat generated at joints may dissipate to nearby winding over a certain length, leading to potential breakdowns due to creep, insulation damage and short-circuit. Different types of joints like Western Union Splice (WUS), soldered WUS, crimp and butt are commonly used to connect the HV winding conductors of DTs. Aluminium (Al) and Copper (Cu) are the two commonly used conductor materials in DTs. The Al is used as conductor material in most of the DTs of lower ratings (16-250 kVA) instead of Cu. However, only a few power utilities like Tamil Nadu Power Distribution Corporation Limited (TNPDCL), India, specifies the use of Cu wound DTs exclusively, regardless of the rating. Due to the material differences, the joints using Al conductors cannot achieve the same level of effectiveness as those with Cu conductors. A field study of failed DTs was performed to identify the condition of different winding joints and the level of degradation in the joints due to service exposure. The contact resistance of Al-Al and Al-Cu winding joints of the failed Al wound DTs indicates significant degradation due to service exposure. The winding joints in this condition may tend to form hot spots, potentially reducing the lifespan of DTs. Since joints are unavoidable in the fabrication of DT winding, it is important to examine the performance of the different joints for their suitability in the construction of DTs. Tue, 01 Jul 2025 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/21762 2025-07-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/21761 Title: VISION BASED LANE DETECTION TECHNIQUES AND DRIVER STATE MONITORING FOR ADAS Authors: Nagineni, Sukumar Abstract: The present research work aims to develop Advanced Driver Assistance System (ADAS) features, those are namely vision-based lane detection and tracking techniques, and driver state monitoring system. Lane feature extraction is a primary step for lane detection in ADAS. In connection with the lane feature extraction, an edge map feature generation technique based on a two-dimensional discrete Fourier transform (DFT) with a sliding window is proposed for road images to detect the lanes and road markings. The 2 × 2 sliding window DFT based kernels with bin indices (k1, k2 = 0, 1) for horizontal edge detection and (k1, k2 = 1, 0) for vertical edge detection have been proposed. The 2-D sliding discrete Fourier transform (SDFT)-based edge detector has been proven to be more efficient for lane and road marking images in comparison with conventional edge detectors and cellular neural network-based edge detectors. In the presence of noise and various signal-to-noise ratio conditions, the horizontal and vertical edges have been efficiently recovered with good Pratt figure of merit (PFOM) without applying any pre-processing, noise removal process, and post-processing techniques. The PFOM was found to be quite stable, with a wide threshold range for various noise levels. The consistent performance of the proposed edge detector is proved with MSE and PSNR determination of detected edge images. Moreover, the proposed 2-D SDFT-based edge detector performs well in developing edge maps for real-time road videos. The systemon- chip implementation of the 2-D SDFT edge detector on Cyclone IV FPGA chip is also carried out for detecting the lane and road markings. Tue, 01 Oct 2024 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/21761 2024-10-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/21746 Title: State and Line Parameter Estimation in Three Phase Distribution System Authors: Alam, Mohd Tauhid Abstract: The necessity for safe and stable techniques for monitoring, control, and operation of a distribution system has become increasingly important in the last few decades. The load flow analysis and state estimation are the most crucial components in monitoring and operational studies. Moreover, load flowstudies and state estimation are distinct methodologies utilized in transmission/ distribution system. The load flowanalysis is a method that gives a deterministic study of the network under steady-state conditions. In contrast, state estimation provides the most accurate estimates of the real operating condition of the distribution network while accounting for the presence of noisy as well as bad measurements. The architecture and radial topology of the distribution network differ significantly from those of the transmission network. Because of unbalanced nature of the distribution system, the state estimation (SE) algorithm originally intended for the transmission system needs to be suitably modified for the distribution system. The distribution system is usually unbalanced in nature configuration and has short feeder sections with higher R/X ratio resulting in higher I2R losses. Unlike transmission network, the distribution system is characterized by its vast geographical spread and limited realtime measurement which can lead to significant observability challenge. Despite the recent implementation of advanced metering infrastructure (AMI), the installation of smart meters at all nodes is not economically feasible. State estimation technique usually assumes that the line parameters values of a distribution network are exactly known. Nevertheless, this assertion is inaccurate, as the operating values of the line parameter can vary over a period of time due to factors such as ambient temperature, and conductor degradation. Seasonal fluctuations in soil resistivity and temperature are critical environmental factors that substantially influence the values of line parameters. In addition, human errors such as misreading, inaccuracies in the database input, and various measurement methods can lead to variations in the network parameters. Fri, 01 Aug 2025 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/21746 2025-08-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/21637 Title: Parallel Converter Fed High-Performance PMSM Drive with Reduced Circulating Current Meant for High-Speed Applications Authors: Nariya, Drashtiben Madhavjibhai Abstract: High-speed permanent magnet synchronous motor (PMSM) drives are preferred for high-speed electric vehicle applications due to their high power density and efficiency. This project aims to enhance drive performance by reducing peak-peak torque ripple and total harmonic distortion (THD) in motor line current over the entire range of frequency. In this project, two parallel converter-fed permanent magnet synchronous motor drives are proposed and it is compared with the single converter-based Stan dard PMSM drive. Standard PMSM drive consists of a voltage source inverter (VSI) feeding a permanent magnet synchronous motor operated in vector control mode. Such motor drives operate at a fundamental frequency of more than 750 Hz and power levels ranging up to a few tens of kW (≥ 50 kW). The rated speed for PMSM used in the standard PMSM drive is 5500 rpm. High-speed operations result into high switching frequency for the inverter which can lead to switching energy losses reducing the efficiency of the drive and deteriorating the thermal performance of the drive. To restrict switching energy losses, the switching frequency is restricted below 10 kHz for standard PMSM drive. Thus, the pulse number (i.e., the ratio of switch ing frequency and fundamental frequency) drops below 15 over moderate and high fundamental frequency operation. Consequently, drive performance deteriorates sig nificantly in terms of total harmonic distortion in line current and peak-peak torque ripple. This project proposes parallel converter-based PMSM drive-I to improve mo tor line current THD and peak to peak torque ripple through carrier interleaving. Through carrier interleaving, the optimum interleaving angle can be analyzed which can reduce torque ripple significantly. An optimized interleaving angle is identified to confine high frequency circulating current within ratings of power converter while maintaining nearly minimum THD in motor line current. Operation of converters in parallel produces high circulating current which can increase energy losses in the drive. Thus, the performance of the drive deteriorates when operated for longer durations. To achieve a reduction in circulating current flowing between converters without compromising on line current THD and torque ripple, this project further proposes coupled inductors based PMSM drive-II. Proposed PMSM drive-II also uses vector control for the drive operation. Value for the coupled inductor is chosen in such a way that both the proposed PMSM drives can be fairly compared in terms of circulating current while maintaining the same motor line current THD and peak to peak torque ripple as the proposed drive-I. The performance of proposed PMSM drives I and II are compared with the standard PMSM drive in terms of line current THD and peak to peak torque ripple. Simulation results pertaining to three-phase, 50 kW, and 916 Hz PMSM drive are presented in the report to validate the propositions. A Trial version of plecs software is used to generate the results. Mon, 01 May 2023 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/21637 2023-05-01T00:00:00Z