Dynamic Soil Structure Interaction Analysis of Pile Supported High Rise Structures

Experiences from past earthquake disasters clearly shows that the ground motion was responsible for majority of property and life loss. Among the collapsed structures during the 1964 Niigata earthquake, the 1995 Kobe earthquake, the 1999 Koceli earthquake, the 2001 Bhuj earthquake and the 2004 Sumatra earthquake, excessive damage was occurred to pile supported bridges, towers, chimneys, high rise structures, etc. In view of this there is a need to study the complex behavior of soil-pile-structure interaction problems using numerical methods. In this research paper, a numerical study is carried out to understand the dynamic soil structure interaction of a high rise structure in a visco elastic half space in the presence of near by pile supported structures. The structure soil structure interaction is modelled by considering the direct methodology using a Finite element method based code ANSYS 10. Initially a two dimensional study is carried out for understanding the seismic response of group of high rise structures supported on pile foundations. The linear super structures are considered as framed structures of different dynamic characteristics suported on group of piles. Different case studies are made one in which the group effect of structures supported on piles are considered like group of two identical structures, group of three identical structures and group of three different structures, second one in which the effect of variability in structure height is considered like 5 storey structure, 10 storey structure and 15 storey structure and the third one in which the effect of variability in structure shape is considered. For each case the effect of structure soil structure interaction on seismic response is compared with fixed base response

Harmonic elimination control of a five-level DC-AC cascaded H-bridge hybrid inverter

A five-level hybrid cascaded inverter operating under selective harmonic elimination (SHE) pulse-width modulation (PWM) control is discussed in this paper. The topology is a cascaded connection of a conventional three-phase, two-level inverter and an H-bridge module for each phase with a single DC-source. The topology boosts the output voltage within limits and with no additional DC-DC converters. However, such boosting feature depends on the control of the floating capacitor voltage and the load power factor. The regulation of the floating capacitor for the given modulation strategy is also analyzed. Experimental results taken from a single-phase laboratory prototype are presented to confirm the operational characteristics of the converter

Five-level active NPC converter topology: SHE-PWM control and operation principles

The neutral-point-clamped (NPC) inverter topology has been the centre of research and development effort for numerous applications, including medium- and high-voltage electric motor drives, static compensators (STATCOMs) and other utility type of power electronic systems for almost three decades now. Pulse-width modulation (PWM) control methods have been developed for such topology for respective three-level and multilevel versions. The issue of voltage balancing between the DC bus capacitors is a drawback that requires attention and the problem becomes more serious as the number of levels increases. Selective harmonic elimination PWM can be applied to control the topology as a method to reduce the switching transitions to the lowest possible number. The active NPC (ANPC) topology is derived from the NPC topology by adding an active switch in anti-parallel to each clamping diode. Hybrid configurations combining flying capacitors are also possible. The five-level topology discussed in this paper is derived through different connections of active clamping paths. A novel recently proposed five-level symmetrically defined SHE-PWM method is applied. The simulation results presented in the paper confirm the suitability of the new method

The seven-level flying capacitor based ANPC converter for grid intergration of utility-scale PV systems

The installed capacity of grid connected PV plants has increased significantly over the past few years and is expected to continue its growth over the next decade due to the continuous demand for renewable energy and distributed generation systems. This paper presents a seven-level flying capacitor (FC) based active neutral point clamped (ANPC) converter for the connection of utility-scale PV system to the electricity grid. The multilevel voltage output of the topology provides high quality waveforms while maintaining the operational characteristics of NPC based converters for PV systems. The converter topology together with a method to regulate the FC voltages to their reference values and an optimal third harmonic injection for utilization of the DC-link voltage are presented. Simulation results for the operation of the grid connected converter under steady state and transient operation are provided in order to demonstrate the operation and performance of the topology in grid connected applications. © 2012 IEEE

Harmonic elimination control of a five-level DC-AC cascaded H-bridge hybrid inverter

A five-level hybrid cascaded inverter operating under selective harmonic elimination (SHE) pulse-width modulation (PWM) control is discussed in this paper. The topology is a cascaded connection of a conventional three-phase, two-level inverter and an H-bridge module for each phase with a single DC-source. The topology boosts the output voltage within limits and with no additional DC-DC converters. However, such boosting feature depends on the control of the floating capacitor voltage and the load power factor. The regulation of the floating capacitor for the given modulation strategy is also analyzed. Experimental results taken from a single-phase laboratory prototype are presented to confirm the operational characteristics of the converter

Novel approaches in monitoring and determining the relationships between pre- and post-hatch metabolic parameters in progeny of young broiler breeders

Seven experimental trials were conducted to develop and use novel techniques to examine the relationships between pre- and post-hatch physiological parameters in the progeny of young broiler breeders. Trials 1, 2 and 3 together examined the safer and effective use of transponders to determine embryonated egg air cell temperature (Temb) as an estimation of broiler embryo temperature during incubation, and to subsequently calculate eggshell water vapor conductance (GH2O), specific GH2O (gH2O) and GH2O constants (KH2O) in modern broiler strains. Trials 4 and 5 together examined the relationships of early, middle and late post-hatch growth quality parameters and tissue nutritional profiles of broilers with the corresponding Temb, GH2O, gH2O and KH2O. Furthermore, Trials 6 and 7 together examined the changes in nutritional profiles and histological structures of the broiler embryonic pipping muscle between 15 and 19 days of incubation. Based on the results from Trials 1, 2 and 3, it was concluded that transponders may be effectively implanted in the embryonated egg air cells with minimal invasion to the broiler embryo to efficiently determine Temb, and to subsequently calculate GH2O, gH2O and KH2O of modern broiler strain eggs during incubation. The results from Trials 4 and 5 also suggested that within physiological limits, an increased gH2O results in increased embryo metabolism, which subsequently increases growth and yolk sac absorption in the corresponding broiler chicks through 3 days post-hatch. Moreover, it was also observed that a higher gH2O was negatively associated with chick hydration status on day 28 post-hatch; although such effects were not observed through day 48 of the post-hatch grow out period. It was concluded that the effects of gH2O on post-hatch broiler physiology may be more pronounced during early and middle post-hatch periods and may subside as the chick reaches marketing age. Furthermore, the results from Trials 6 and 7 indicated that changes in the nutritional profiles of the pipping muscle occur in accordance with corresponding changes in liver metabolism, and that these together with associated morphological changes in the pipping muscle, as observed through histological techniques may be critical for the broiler embryo’s preparation for hatch

DC-link voltage ripple compensation for multilevel active-neutral-point- clamped converters operated with SHE-PWM

This paper presents a dc-link voltage ripple compensation method for flying-capacitor (FC)-based active neutral- point-clamped multilevel converters operating under selective harmonic elimination pulsewidth modulation. The method is based on feedforward modifcation of the modulation index according to the ripple on the dc-link voltage, effectively altering the switching control functions. The low-order harmonics in the output due to the presence of the dc-link ripple are eliminated. In addition, a control strategy that actively regulates the flying capacitor voltages of each phase to the reference value and controls the neutral point voltage deviation is implemented. The performance of the dc ripple harmonic compensation method and regulation strategies are evaluated through simulation and experimental results from a three-phase, five-level laboratory prototype

An n-level flying capacitor based active neutral-point-clamped converter

An n-level flying capacitor (FC) based active neutral point clamped (ANPC) converter is discussed in this paper. The converter is based on an arrangement of a three-level ANPC converter and a number of two-level cells creating an n-level line-to-neutral waveform. The converter is operated under a phase-shifted carrier pulse-width modulation (PWM). The mathematical model for the DC-link capacitors voltage behavior of a three-phase arrangement is also presented. It is shown through simulations and experimental work that the voltage of flying capacitors can naturally balance to the required level in order to generate multilevel waveform. Simulations and experimental work of a single-phase seven-level ANPC converter prototype are also presented

SHE-PWM switching strategies for active neutral point clamped multilevel converters

The main drawback of the diode neutral-point-clamped (NPC) converter is the unequal loss distribution among the semiconductor devices which confines the maximum output power and the switching frequency. To address this drawback, switching state redundancy is required to evenly distribute the losses and can be achieved differently as the level of the converter changes. For instance, the three-level active NPC (3L-ANPC) converter has switching state redundancy and is derived from the 3L-NPC converter by adding an anti-parallel switch to the clamping diodes; in the 4L-ANPC converter, the combination of a 2L converter and a 3L-ANPC converter is used; in a 5L-ANPC converter, the combination of the 3L-ANPC and 3L-flying capacitor (FC) converter is advantageous. The paper discusses selective-harmonic-elimination (SHE) pulse-width-modulation (PWM) strategies for the above mentioned converters and explains how loss distribution can be achieved