Recursos de colección

ETD at Indian Institute of Science (3.494 recursos)

Repository of Theses and Dissertations of Indian Institute of Science, Bangalore, India. The repository has been developed to capture, disseminate and preserve research theses of Indian Institute of Science.

Electrical Engineering (ee)

Mostrando recursos 1 - 20 de 136

  1. Control Strategies for Seamless Transition between Grid Connected and Islanded Modes in Microgrids

    Das, Dibakar
    The popularity of distributed generating (DG) sources have been increasing over the past few years. With the increasing penetration of these DGs, the concept of micro grid is becoming popular. A micro grid is a small power system network with distributed generating sources which can operate seamlessly irrespective of the presence of the utility grid. Operating the micro grid in this manner increases system reliability and reduces power interruptions. However, it introduces several control challenges. This thesis aims at analysing the behaviour of a micro grid system during the transition between grid connected mode and islanded mode of operation and...

  2. Developmental Studies on Ultra Wide Band Type High Power Electromagnetic Radiating System for Use as an Intentional Electromagnetic Interference Source

    Hiralal, Bhosale Vijay
    The electronic control, instrumentation and communication hardware is becoming more and more compact and faster in operation due to the increased use of large scale integration of semiconductor devices operating at higher speeds. The use of VLSI circuit based systems in various industrial and defence sectors is also increasing continuously. Since the operating threshold voltages and currents of these devices are very small they are very prone to electrical disturbance in their operation by the Electromagnetic Interference (EMI) signals. Their proper functioning is very important particularly in the case of systems used in mission mode, critical defence/industrial platforms. EMI can...

  3. Low Switching Frequency Pulse Width Modulation for Induction Motor Drives

    Tripathi, Avanish
    Induction motor (IM) drives are employed in a wide range of industries due to low maintenance, improved efficiency and low emissions. Industrial installations of high-power IM drives rated up to 30 MW have been reported. The IM drives are also employed in ultra high-speed applications with shaft speeds as high as 500; 000 rpm. Certain applications of IM drives such as gas compressors demand high power at high speeds (e.g. 10 MW at 20; 000 rpm). In high-power voltage source inverter (VSI) fed induction motor drives, the semiconductor devices experience high switching energy losses during switching transitions. Hence, the switching...

  4. Active Power Flow Tracing for Preventive Control in Deregulated Power Systems

    Adhip, *
    Modern day power systems present an open access environment, inspiring participation from small scale and large power suppliers. With multiple players in the system driven by the market, proper monitoring and control of system becomes a major concern. This transformation is accompanied by dynamic consumption patterns and rising power demands. The expanding network encompassing EHV/AC network, HVDC and FACTS devices, along with increased penetration of renewable sources, viz. solar and wind energy at medium and low voltage levels, adds to the problem. Independent System Operators (ISO) are entrusted with ensuring smooth operation, and employing proper preventive measures to eliminate a...

  5. Design and Analysis of Real-time Message Scheduling under FlexRay Protocol

    Sunil Kumar, P R
    A typical automobile system consists of many Electronic Control Units (ECUs) for the purposes of safety, comfort, and entertainment applications. FlexRay is a high bandwidth protocol for such automotive requirements, which facilitates communication between distributed ECUs. This thesis addresses some of the issues associated with the design and implementation of the FlexRay protocol. The number of ECUs that are used in automobiles has an increasing trend to implement more functionality, which demands more bandwidth. By minimizing bandwidth requirements for servicing a given workload of periodic and sporadic real-time tasks, one can connect more ECUs to the same FlexRay bus. With...

  6. Real Time Face Recognition on GPU using OPENCL

    Naik, Narmada
    Face recognition finds various applications in surveillance, Law enforcement etc. These applications require fast image processing in real time. Modern GPUs have evolved fully programmable parallel stream processors. The problem of face recognition in real time system is benefited by parallelism. With the aim of fulfilling both speed and accuracy criteria we present a GPU accelerated Face Recognition system. OpenCL is a heterogeneous computing language that allows extracting parallelism on different platforms like DSP processors, FPGAs, GPUs. The proposed kernel on GPU exploits coarse grain parallelism for Local Binary Pattern (LBP) histogram computation and ELTP (Enhanced Local Ternary Pattern) feature...

  7. Behavior of Distance Relay Characteristics on Interconnecting Lines Fed From Wind Farms

    Srivastava, Sachin
    Distance relays due to their selectivity and operating speed are used in HV/EHV line protection. The dynamic nature of Mho characteristic, which happens to be most primitive technique in line protection implemented with distance relaying, is built by using the measurement of local voltage and current signals. These signals have been influenced substantially by fault resistance and the source impedance feeding the line. In case of different generation sources, the source impedance and fault characteristic also change accordingly. Environmental benefit of wind turbine technology is making it a potential source of energy. These wind turbine-generating units (WTGU) use rugged induction/synchronous...

  8. Efficient Design of Embedded Data Acquisition Systems Based on Smart Sampling

    Satyanarayana, J V
    Data acquisition from multiple analog channels is an important function in many embedded devices used in avionics, medical electronics, robotics and space applications. It is desirable to engineer these systems to reduce their size, power consumption, heat dissipation and cost. The goal of this research is to explore designs that exploit a priori knowledge of the input signals in order to achieve these objectives. Sparsity is a commonly observed property in signals that facilitates sub-Nyquist sampling and reconstruction through compressed sensing, thereby reducing the number of A to D conversions. New architectures are proposed for the real-time, compressed acquisition of...

  9. Lightning Threat to Cables on Tall Towers and the Question of Electrical Isolation

    Kunkolienker, Govind Ramrao
    Electromagnetic effects of lightning currents during a direct hit to tall communication towers, other instrumented towers and chimneys can be hazardous to associated cables, as well as, electrical and electronics systems. The standard practice in telecommunication and other related fields is to bond the cable sheath to the tower and ground connection is made before it enters the base station. However, in some specific cases when power, signal and data logging cables are to be supported on the same tower, isolation of power cables is demanded. In a totally different situation, attempts are also made to have a dedicated isolated...

  10. Operation of Three Phase Four Wire Grid Connected VSI Under Non-Ideal Conditions

    Ghoshal, Anirban
    The necessity to incorporate renewable energy systems into existing electric power grid and need of efficient utilization of electrical energy are growing every day. A shunt connected Voltage Source Inverter(VSI) capable of bidirectional power flow and fast control has become one of the building block to address such requirements. However with growing number of grid connected VSI, new requirements related to harmonic injection, higher overall efficiency and better performances during short term grid disturbances have emerged as challenges. For this purpose a grid connected three phase four wire VSI with LCL filter can be considered as a general module to...

  11. Reactive Power Co-ordination in Grid Connected Wind Farms for Voltage Stability Enchancement

    Reddy, Kommi Krishna
    Recent decades have witnessed a significant increment in power contribution from wind generators. This increment in penetration requires power engineers to tackle multi-fold challenges concerning operational and stability aspects. There exists a significant attention among the researchers in analyzing the impact of wind generation on various system aspects. This thesis focuses on steady state voltage stability aspects with penetration of Variable speed wind generators. Traditionally, ancillary services are supplied by large conventional generators. However, with the huge penetration of wind generators as a result of the growing interest in satisfying energy requirements, and considering the benefits that they can bring along...

  12. Generalized Analytic Signal Construction and Modulation Analysis

    Venkitaraman, Arun
    This thesis deals with generalizations of the analytic signal (AS) construction proposed by Gabor. Functional extensions of the fractional Hilbert Transform (FrHT) are proposed using which families of analytic signals are obtained. The construction is further applied in the design of a secure communication scheme. A demodulation scheme is developed based on the generalized AS, motivated by perceptual experiments in binaural hearing. Demodulation is achieved using a signal and its arbitrary phase-shifted version which, in turn translated to demodulation using a pair of flat-top bandpass filters that form an FrHT parir. A new family of wavelets based on the popular Gammatone...

  13. Control, Modulation and Testing of High-Power Pulse Width Modulated Converters

    Sivaprasad Sreenivasa, J
    Experimental research on high-power converters, particularly in an academic environment, faces severe infrastructural constraints. Usually, power source and loads of required ratings are not available. Further, more importantly, the energy consumption is huge. One possibility is to establish an experimental research platform, comprising of a network of high-power converters, through which power is circulated and which draws only the losses from the mains. This work deals with the establishment of a circulating power test set-up, comprising of two line-side PWM converters, inclusive of control and modulation methods for the two converters. Two types of circulating power test setups are developed....

  14. Optimum Savitzky-Golay Filtering for Signal Estimation

    Krishnan, Sunder Ram
    Motivated by the classic works of Charles M. Stein, we focus on developing risk-estimation frameworks for denoising problems in both one-and two-dimensions. We assume a standard additive noise model, and formulate the denoising problem as one of estimating the underlying clean signal from noisy measurements by minimizing a risk corresponding to a chosen loss function. Our goal is to incorporate perceptually-motivated loss functions wherever applicable, as in the case of speech enhancement, with the squared error loss being considered for the other scenarios. Since the true risks are observed to depend on the unknown parameter of interest, we circumvent the...

  15. Hall-Effect Current Sensors for Power Electronic Applications : Design and Performance Validation

    Kumar, Ashish
    Closed loop Hall-effect current sensors used in power electronic applications require high bandwidth and small transient errors. For this, the behaviour of a closed loop Hall-e ect current sensor is modeled. Analytical expression of the step response of the sensor using this model is used to evaluate the performance of the PI compensator in the current sensor. Based on this expression a procedure is proposed to design parameters of the PI compensator for fast dynamic performance and for small transient error. A prototype closed loop Hall-effect current sensor is built in the laboratory. A PI compensator based on the procedure...

  16. Studies on Electrical Treeing in High Voltage Insulation Filled with Nano-Sized Particles

    Alapati, Sridhar
    Polymers are widely used as insulating materials in high voltage power apparatus because of their excellent electrical insulating properties and good thermomechanical behavior. However, under high electrical stress, polymeric materials can get deteriorated which can eventually lead to the failure of the insulation and thereby the power apparatus. Electrical treeing is one such phenomena whereby dendritic paths progressively grow from a region of high electrical stress and branch into conducting channels in a solid dielectric. The propagation of electrical trees is of particular interest for the power industry as it is one of the major causes of failure of high...

  17. Transient Analysis of EHV/UHV Transmission Systems for Improved Protection Schemes

    Ravishankar, Kurre
    Ever increasing demand for electricity, exploitation of large hydro and nuclear power at remote location has led to power evacuation by long EHV/UHV transmission systems. This thesis concentrates on transient analysis of EHV/UHV transmission systems for improved planning and protection. In this thesis, the uncontrolled and controlled switching methods to limit the switching surges during energization of 765kV and 1200k VUHV transmission lines are studied. The switching surge over voltages during the energization of series compensated line are compared with uncompensated line. A Generalized Electromagnetic Transients Program has been developed. The program incorporates specific models for studying the effectiveness of various...

  18. Supervised Learning of Piecewise Linear Models

    Manwani, Naresh
    Supervised learning of piecewise linear models is a well studied problem in machine learning community. The key idea in piecewise linear modeling is to properly partition the input space and learn a linear model for every partition. Decision trees and regression trees are classic examples of piecewise linear models for classification and regression problems. The existing approaches for learning decision/regression trees can be broadly classified in to two classes, namely, fixed structure approaches and greedy approaches. In the fixed structure approaches, tree structure is fixed before hand by fixing the number of non leaf nodes, height of the tree and paths...

  19. A Networked Control Systems Framework for Smart Grids with Integrated Communication

    Sivaranjani, S
    Over the last decade, power systems have evolved dramatically around the world, owing to higher demand, stringent requirements on quality and environmental concerns that are becoming increasingly critical. With the introduction of new technologies like large-scale renewable energy, wide-area measurement based on phasor measurement units (PMUs) and consumer interaction in the distribution system, the power grid today has become more potent than ever before. Most of the defining features of the smart grid today rest on the integration of advanced communication capabilities into the grid. While communication infrastructure has become a key enabler for the smart grid, it also introduces...

  20. Study on Pulsewidth Modulation Techniques for a Neutral-Point-Clamped Voltage Source Inverter

    Das, Soumitra
    Neutral-point-clamped (NPC) three-level inverter is capable of handling higher dc bus voltage and producing output waveform of better quality than a conventional two-level inverter. The main objective of the present work is to analyze the existing PWM schemes for two-level and three-level inverters in terms of line current ripple, and to design new PWM techniques for the NPC inverter to reduce line current distortion. Various discontinuous PWM or bus-clamping PWM (BCPWM) methods for a two-level voltage source inverter are analyzed in terms of rms line current ripple, which is evaluated by integrating the error voltage (i.e. error between the applied...

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