Proposed Conversion System Research Articles

Performance Analysis of a Quasi-Z-Source Converter for Solar Photo Voltaic System Powered Water Pumping System

The integration of three different DC/DC boost converters is proposed in this study, namely the conventional BC, ZSC, and QZSC, in a solar photovoltaic system (SPVS). The front-end converters are utilized for the integration of the SPVS and a three-phase voltage source inverter (VSI), which powers a Brushless DC Motor (BLDC) motor. Two different algorithms, INC-MPPT and INC-trained ANN (INC-ANN-MPPT), are employed for optimizing power extraction from the SPVS. The back-end converter comprises the VSI, which is controlled by two controllers: a conventional MPP DC link voltage (V dc) reference controller and a closed-loop speed dual-tuned PID (VSDT-PID) controller. Additionally, a trained ANN controller (VSDT-ANN) with hall effect feedback is utilized to optimize the motor speed. The back-end converter effectively regulates the speed of the BLDC motor, regardless of the irradiance level of the SPVS. The proposed conversion system is analyzed in MATLAB/Simulink, considering various system configurations and its performance is compared with an implemented conversion system in terms of power extraction, transient response, settling time, voltage, current, and speed deviations.

Optical format interconversion nodes between OOK and QPSK enabled by a reconfigurable two-dimensional vector mover.

An optical format interconversion scheme between on-off keying (OOK) and quadrature phase shift keying (QPSK) is proposed and verified in this paper. The conversion system mainly consists of a coherent vector combiner and a reconfigurable two-dimensional (2D) vector mover. As a key element of the proposed conversion system, the 2D vector mover is implemented by a non-degenerate phase-sensitive amplifier (PSA). The operating principle and theoretical derivations of the PSA-based 2D vector mover are fully introduced. The reconfigurable transfer characteristics of the vector mover are analyzed under different parameter settings to exhibit the flexible 2D moving function. The signal constellations, eye diagrams, spectrum, error vector magnitudes, and bit error ratios are estimated and depicted to validate the proposed idea. With the input signal-to-noise ratios of 20 dB and 25 dB, error-free conversions are achieved between 50G Baud OOK and QPSK. The scheme proposed in this paper fills the lack of the one-to-one interconversion between OOK and QPSK, and has potential applications in optical interconnect nodes, across-dimensional optical transmissions, and flexible optical transceivers.

An Efficient Asymmetric Direct Current (DC) Source Configured Switched Capacitor Multi-level Inverter

This paper is dealing about Switched Capacitor Multi-Level Inverter (SCMLI) circuit which is controlled by triangular multicarrier Sinewave Pulse Width Modulation (SPWM) technique. The proposed SCMLI is powered from asymmetric DC source configuration to obtain multi-level output voltage by applying switching pulse to the main circuit from control circuit for switching operation. Fourteen switches and four capacitors are employing to do the proposed inversion operation in an effective way. Switching capacitors can perform boost operation to enhance voltage from the source level to the required level. Input DC from the asymmetric sources is converted to AC voltage for the application of consumers. This proposed conversion system is applicable for mainly in industrial and renewable energy-based energy conversion system because it can carry high output voltages. This proposed method gives about more efficiency. Also reduces switching losses in lower value, low conduction losses and capacitor ripple losses. The simulation model is analyzed in MATLAB/SIMULINK platform and the same validated in hardware results. The developed SCMLI structure is witness over other topologies for the power inversion process in the multi-level.

Electromagnetic‐based maximum output power control in new two‐layer BLDC generator using optimal control of turn‐on and turn‐off angles in variable speed applications

In this study, by using the electromagnetic field analysis, the design of brushless DC generator with a novel construction and controller, appropriate for variable speed applications, is proposed. In the proposed machine, unlike the conventional structure, an assisted DC field coil is employed instead of permanent magnet excitation to provide a regulated voltage. Results of the electromagnetic field analysis show that including the DC field coil increases the controllability of the flux in different machine parts which provide a regulated terminal voltage in a wide speed range appropriate for variable speed applications. Moreover, the maximum power point tracking is achieved by controlling the DC field current along with producing optimal turn-on and turn-off angles for stator winding using the electromagnetic analysis based on optimal finite element analysis. Also, an appropriate controller is designed to control the DC field coil current. To verify the actual performance of the proposed configuration, a 1.5 Kw machine is manufactured and tested followed by the discussion on results. The obtained experimental results are in good agreement with the results of the electromagnetic analysis which confirm the maximum power trackability and robust output voltage regulation of the proposed conversion system under different shaft speeds and load conditions.

Method for Separation of Blood Vessels on the Three-Color Images of Biological Tissues

A new technology was developed to improve the visibility of blood vessels on images of tissues of hollow human organs(the alimentary tract and respiratory system) based on the relation between the color components of the image, the scattering properties of the tissue, and its hemoglobin content. A statistical operator was presented to convert the three-color image of the tissue into a parametric map objectively characterizing the concentration of hemoglobin in the tissue regardless of the illumination and shooting conditions. An algorithm for obtaining conversion parameters for image systems with known spectral characteristics was presented. An image of a multilayer multiple-scattering medium modeling bronchial tissue was synthesized and was used to evaluate the efficiency of the proposed conversion system. It was shown that the conversion made it possible to increase the contrast of the blood vessels by almost two orders of magnitude, to significantly improve the clarity of the display of their borders, and to eliminate almost completely the influence of background and nonuniform illumination of the medium in comparison with the original image.

Modeling, Design, and Implementation of a Power Conversion System for Small-Scale High-Altitude Wind Power Generating System

This paper presents a compact portable power conversion system (PCS) for small-scale high-altitude wind power (HAWP) generating system. The proposed PCS interfaces the variable voltage and variable frequency ac power to the distribution level grid voltage. The PCS consists of a three-level Vienna rectifier for the generation-side control, a soft-switched half-bridge dc–dc converter for isolation and step down, and a two-level inverter for grid interface. The proposed conversion system uses a smaller number of active semiconductor devices that reduces overall losses, and thereby, increases power density of the converter. The sensorless optimal torque control technique (using $d-q$ frame) with output voltage balance is proposed and implemented for the generation-side maximum power-point tracking control. A modified proportional-resonant-based control method is proposed for grid-side current control. Simulation studies have been carried out using MATLAB and PSIM. A laboratory prototype is developed and tested for a scaled-down model. The experimental results validate the performance of the PCS for interfacing HAWP into the grid/load.

Analysis of hydrogen production from wind energy in the southeast of Iran

In recent years more attention has been paid to renewable and clean sources of energy like wind. Due to the uncertainties related to wind turbines, issues of energy storage are significant. One of the most appropriate methods of energy storage is the production of hydrogen. The main aim of this paper is to investigate the capability of wind energy for producing hydrogen in the south eastern province of Sistan & Baluchestan in Iran. This paper analyzes four different wind turbines with a capacity of 300–900 kW in five locations, in Dalgan, Lutak, Mil-Nader, Nosratabad and Zahedan. In this study, two approaches were used; the actual average wind turbine power and the Weibull. It was found that EWT Directwind 500/54 provides the best capacity factor among all examined turbines with the highest value of 50.77% for the station at Lutak. Additionally, the highest energy production was from the AWE 52-900 wind turbine with an annual production of 2462.5 MWh. A wind-hydro system consisting of a power controller, a high efficiency rectifier, and an alkaline electrolyzer was considered. The proposed conversion system resulted in a linear relationship between generated wind turbine energy and the amount of hydrogen produced. Therefore, the highest amount of yearly hydrogen production (39.82 ton-H2) is related to the largest examined wind turbine, installed in the station at Lutak.

An Adaptive Control Strategy for a Wind Energy Conversion System Based on PWM-CSC and PMSG

This paper proposes a new adaptive control strategy for a wind energy conversion system based on a permanent magnet synchronous generator and a pulse-width modulated current source converter. Most of the studies on wind farms are based on double fed induction technology. Nevertheless, the proposed conversion system is a good alternative due to its high efficiency and reliability. Electrolytic capacitors are not required in this type of converter and the voltage in the DC-link as well as the generated reactive power can be dynamically modified according to the wind velocity, being even negative if required. However, it is challenging from the control and stability standpoint. Capacitive filters placed on the AC side, which are required for safe commutation, can create resonances with the power grid. Reactive power is generated according to the capacity of the converter, the wind velocity and the load profile. The adaptive control strategy uses an adaptive PI which is self-tuned based on a linear approximation of the power system calculated at each sample time. A model reference is also proposed in order to reduce the post-fault voltages. Simulation results demonstrate the advantages of the proposed control.

Novel Energy Conversion System Based on a Multimode Single-Leg Power Converter

This paper presents a novel power conversion topology for systems, which include a boost and bidirectional converters to control the power flows between sources, batteries, and ultracapacitors. The proposed system (multimode single-leg power converter) substitutes the boost converter and bidirectional converter with a multifunctional bidirectional converter and has cost effectiveness and fault tolerance, preserving the same energy conversion functionalities of the conventional energy conversion system. To verify the performance of the proposed system, its operations are categorized and explained to four different modes. Then, each mode of the proposed system is simulated and implemented experimentally using a prototype test bed. The results present that the proposed conversion system is feasible and applicable for a wide range of applications including alternative/renewable power systems and electric vehicles (EVs).

An All-Optical Transformer From Differential NRZ Data to Ultra-Wideband Pulse Stream

We propose and experimentally demonstrate a compact and cost-effective scheme based on a fiber Sagnac structure to realize real time conversion from differential nonreturn-to-zero (NRZ) data to ultra-wideband (UWB) pulse stream. The proposed conversion system for the UWB signal generation consists of a single-wavelength laser, a phase modulator, several polarization controllers, and optical couplers. Due to the optical interference between the two phase-modulated light waves with slight phase difference in the Sagnac loop, two sharp optical pulses with opposite polarities are obtained. With proper time delay, a UWB monocycle pulse stream is generated from the original differential NRZ data. Our proposed method gives a reliable, easy, and low-cost transformer from differential NRZ signal to UWB pulse stream, and no high-speed arbitrary waveform generator (AWG) is required in this all-optical transformer.

Enhancing the Performance of the Marine and Tidal Current Converters Using DC-DC Boost Converter

Due to the highly demand on the renewable energy sources as a free and a clean power resource, extracting energy from unsteady flow using marine and tidal current turbines has a distinct focusing nowadays. For their resource characteristic, extracting energy from marine/tidal current needs a simple and robust converter, which could overcome the drawbacks of the mechanical system such as gearbox and enhance conversion system stability. In this paper a new AC-DC-AC conversion system has been proposed. The new conversion system contains a middle stage DC-DC boost converter, which boost the generated rectified DC voltage higher enough that can enable the PWM inverter to generate the required voltage with the synchronized frequency. In order to investigate the efficient performance of the proposed conversion system especially at low current speed compared to the conventional one, different operating conditions have been studied. Moreover, the effect of including boost converter on the THD (total harmonic distortion) has also been checked. The new conversion system presents its capability to enhance and improve system performance not only with low current speed but also with high current speed.

A Novel Power Conversion Method for Multiple Inverter System using Scott Connected Transformers.

In this paper a novel three phase power conversion system with four units of voltage type single phase inverters, a cycloconverter and Scott connected transformers is proposed for harmonic reduction.The basic operation is described for the conversion system. Turn ratios of the transformers that minimize the total distortion factor of line-to-line voltages, capacity of the transformers and current capacity required for the switching devices are discussed in detail. The total distortion factor of the line-to-line voltages is greatly reduced.The effectiveness of the proposed conversion system is confirmed by experimental results of inverting, rectifying and reactive power compensating operation.

A PROPOSAL FOR WAVE ENERGY CONVERSION NEAR CAPE TOWN

The South African wave energy program has been underway for several years and has included an analysis of the temporal and spatial distribution of wave energy along the full coast-line, determination of energy attenuation perpendicular to the coast-line at a site on the south western coast, and the development of a wave energy converter which is most suited to local conditions and requirements. The resource analysis has shown that the inshore power levels occurring along the south western coast are as promising as any elsewhere in the world. A bottom mounted, V-shaped wave energy conversion device driving an air turbine has been found to be most suited to prevailing conditions. The conversion characteristics of the device are presented, based on 1:100 scale three dimensional and 1:50 scale two dimensional model studies. Preliminary design studies of the proposed conversion system have underlined its potential viability as a cost effective supplementary source of power.