Electrical and Electronics

Ferroresonance is a nonlinear oscillatory phenomenon that occurs under certain conditions. This investigation use an indicator of ferroresonance based on voltage for damping of dangerous overvoltages in coupling capacitor voltage transformers (CCVT). This paper investigates ferroresonance voltage for determination technical requirements of the ferroresonance suppression circuit (FSC) for detection and suppression of ferroresonance. In this technique, by using a back-to-back gated thyristor circuit, a damping resistance is switched to secondary side of the system transformer during dangerous oscillations. The control technique proposed in this paper is a “novel but classic” technique. The prediction of ferroresonance is achieved by detailed modeling using a digital computer transient analysis program such as the EMTP.

In this study, a new approach is proposed for modeling power transformers internal faults by using transmission line model (TLM) and also presented a method to forecasting these kinds of faults by monitoring the effect of partial discharges on transformer primary side current. These monitoring actions boost the reliability of power system. Simulating and detecting loop to loop and loop to ground faults between the desired Transformer’s coil wires in early stages is advantage of this method. Finally, Transformers TLM is implemented with Matlab for observing this method. Simulation results verified application of proposed modeling technique for studying and detecting power transformers different short-circuit faults conditions.

Three phase inverter based welding machine employ resonant high frequency IGBT inverter technology. Due to soft switching scheme, these machines are very rugged and efficient. Currently 3-Phase 160A, 3-Phase 200A, All the TIG machines have built in high frequency igniter circuit for non - contact arc initiation. All these welding machines have Special feature to shut down the internal electronic circuit when machine is kept idle, This feature enhances the life time of machines. Due to such features, Single phase welding machine is having light and saves the electricity up to 60%. Having used for current 20 to 200 A. This machine is moisture free dc welding. The input characteristics are similar to AC, having features such as high max output voltage, stable against voltage fluctuations. Inner loop control for quick system respondence, Peak current control mode make the power devices and stable, against frequent short circuit shocks, Arc thrust function, improve the metal transfer Hot arc ignition function small light and energy saving.

In this work the speech disorder due to damaged Vocal Folds is discussed. The basics of the disorder are described here. The speech parameters are identified which characterize the disorder and correction system is designed to improve the speech quality. The speech signal samples of people of age between five to eighty years are considered for the present study. These speech signals are digitized and enhanced and analyzed for the Jitter, Shimmer, HNR, Pitch variations Tx graphs , Normalized Percentile fo characteristics and % Close Quotient EGG graphs using MATLAB, PRAAT, SFS and EXCEL platforms

This paper presents the model which is developed for single and coupled microstripline structure for both the even and odd-mode of propagation of waves. Most important and common models are: Conformal transformation model, coupled analysis model, hybrid analysis model, numerical analysis by relaxation model, even and odd-mode models, which is the outcome of the coupled line model. H.A. Wheeler derived the characteristic impedance and propagation parameters. Numerical methods are adopted by Stenelhalfer and Sylvester based on pure TEM-mode, Quasi-TEM mode and Non-TEM mode

Doubly fed induction generator (DFIG) based wind turbines have arisen as the leading technologies in wind power market as they offer a variable-speed, economically viable and efficient alternative to the fossil fuel. The present paper comprises of a wind energy conversion system which is simulated using two level pulse width modulation (PWM) converter as well as three level (PWM) converter and their performance under normal and fault conditions are compared. It is observed that multi-level inverters generate purer sinusoidal voltage with reduced total harmonic distortion thus bringing an improvement in the quality of generated power.

A new architecture of multiplier-and-accumulator (MAC) for high-speed arithmetic. In this by combining multiplication with accumulation and devising a hybrid type of carry save adder (CSA), the performance was improved. The CSA tree uses 1’s-complement- based radix-2. Modified Booth’s algorithm (MBA) and has the modified array for the sign extension in order to increase the bit density of the operands. The CSA propagates the carries to the least significant bits of the partial products and generates the least significant bits in advance to decrease the number of the input bits of the final adder. The MAC accumulates the intermediate results in the type of sum and carry bits instead of the output of the final adder, which made it possible to optimize the pipeline scheme to improve the performance.

This paper presents a novel approach to the design and implementation of CPLD (Complex Programmable Logic Devices) based DAS (Data Acquisition System) for varies application. This technique performs the acquisition of physical signal, conversion of analog signal to digital signal and storing of the information. The core heart of the proposed system is CPLD, which allows individual modules on a chip to work independently from each other which is configured and programmed to acquire real time data. The data for the process is acquired using suitable temperature and gas sensors. Signal conditioners are designed for each sensor and are tested in real time. The ADC0808 (analog to digital converter) is adopted for this system, which is a high speed monolithic CMOS device with an 8-bit, 8-channel analog-to-digital converter using successive approximation as the conversion technique. Cool Runner-II CPLD by Xilinx is used as the main controller from which all modules are implemented in VHDL using Xilinx ISE Design Suite9.2 and simulated using Isim.

In a deregulated electricity industry, congestion is most likely to occur and FACTS devices have been proven to be very effective in mitigating this challenge. In this paper a sensitivity based analysis is used to determine the optimal place to locate series FACTS devices, the device used for the investigation is Thyristor Controlled Series Capacitor (TCSC). This approach was tested on the South East Nigerian 11 – bus network. The Power System Analysis Toolbox (PSAT), was used for the simulation of the system. The load flow results obtained showed the effectiveness of the method.

Resonance disorders are observed in patients with a history of cleft palate or cleft lips. Evaluation of speech pathology helps for the proper treatment of a resonance disorder. The speech parameters are identified here which characterizes the disorder and correction system is designed to improve the speech quality. The speech signal samples of people of age between five to eighty years are considered for the present study. These speech signals are digitized and enhanced and analyzed for the Jitter, Shimmer, HNR, Pitch variations Tx graphs , Normalized Percentile fo characteristics and % Close Quotient EGG graphs using MATLAB, PRAAT, SFS and EXCEL platforms.