VOLUME 7, ISSUE 9, SEPTEMBER 2019

Abstract: Scientists have theorized about graphene for decades. It has likely been unknowingly produced in small quantities for centuries, through the use of pencils and other similar applications of graphite. It was originally observed in electron microscopes in 1962, but only studied while supported on metal surfaces. The material was later rediscovered, isolated and characterized in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester. Research was informed by existing theoretical descriptions of its composition, structure and properties. High-quality graphene proved to be surprisingly easy to isolate, making more research possible. This work resulted in the two winning the Nobel Prize in Physics in 2010 "for groundbreaking experiments regarding the two- dimensional material graphene." The global market for graphene is reported to have reached $9 million by 2012, with most of the demand from research and development in semiconductor, electronics, battery energy and composites.

Keywords: Microwave heating, Graphene, Graphene Extraction, Graphite

Abstract: In this paper, design and simulation of High performance Band-pass filter based on CNTFET-COTA using 32nm technology node is proposed. The Cascode Operational Transconductance Amplifier (COTA) is an amplifier whose differential input voltage produces an output current. It is a Voltage Controlled Current Source (VCCS). There is usually an additional input for a current to control the amplifier's transconductance. The COTA is similar to a standard operational amplifier in that it has a differential input stage and that it may be used with negative feedback. The COTA is used as the active building block. It is a new class of Operational Amplifier (OP-AMP). It has flexibility and tunability unlike Op Amp. Further, CNT technology is used to design and simulate proposed structure at 32 nm technology node. The proposed structure uses Carbon Nanotube Field Effect Transistor (CNTFET). In a CNTFET, the channel is made up of parallel combination of SWCNTs. It is observed that the proposed BPF is also consuming low power of 553 nW.

Keywords: CMOS, CNTFET, DC Gain, Cascode -COTA, Power consumption, Filters, BPF

Abstract: This paper presents control characteristic according to controller input signals of the energy storage system in a hybrid wind-diesel power system. The wind power system frequency and the diesel power system frequency are used as controller input signals for control characteristic comparison of the energy storage system. Parameters of the controller according to a input signal of each controller are selected by using the genetic algorithm. In order to evaluate each controller’s performance, the computer simulations are performed for the wind power system disturbance and the diesel power system disturbance. The frequency characteristics, wind power output characteristics, diesel power output characteristics, and output characteristics of the energy storage system are investigated for each disturbance case. Simulation results show that the controller designed using wind system frequency responds faster to wind system disturbance and the controller designed using diesel system frequency responds faster to power system load changes.

Keywords: Wind Power System, Diesel Power System, Hybrid Power System, Energy Storage System, Genetic Algorithm

Abstract: Oil immersed power electrical device being vital and extremely high-priced is main backbone and hub of power transmission & distribution system. Its failure not only causes its own damage however, directly have an effect on the protection, stability and desirableness of the facility grid system. An influence electrical device has to be tested sporadically for its protection and safe operation. These checks embody routine check, temperature rise check, non- conductor kind tests; short withstand check, sound level check, insulation observance tests, impulse check, field service check etc. Mineral oil is wide used as liquid insulation in high voltage instrumentation. Due to environmental issues, recently natural esters are thought of as naturally friendly liquid insulation candidates for prime voltage transformers. Heat and wetness were the most reasons for the degradation of the insulation layer and caused corrosion to the oil tank.

Keywords: Power Transformer, Insulation Oil, Breakdown Voltage (BDV), Moisture Contents, Resistivity, Tan Delta, Interfacial Tension And Flash Point

Abstract: When consumers connect inductive loads to the power system, the power factor lags, creating high current demand, thus high active power losses are incurred in the system. In Nigeria, when the power factor goes below 0.8 (lagging), the electric supply company charge penalty to the consumers. This calls for a system control hence power factor correction. Earlier, the power factor correction was done by adjusting the capacitor bank manually. The automated power factor correction using a capacitive bank helps provide the power factor correction, thereby decreasing the time taken to correct the power factor, which also helps to increase the power efficiency. It has been demonstrated in this work that the phase difference between voltage and current can be determined using zero-crossing detectors, optocouplers, XOR gate, and some primary function of the microcontroller (ATmega 328). Voltage and current transformers have been used for transforming load voltage and current respectively to bring them in the desired working range for the zero-crossing detectors. The device reads the time difference between the line voltage and line current, which is now calculated as the phase angle, and the corresponding power factor is then calculated. If the calculated power factor is less than 0.8, the microcontroller calculates the compensation requirement and accordingly switches on the required capacitor with the aid of an electromagnetic relay. The display used was 16×2 liquid crystal display module. In conclusion, according to the test carried out during simulation for three different inductive loads, the power factor was corrected from 0.59 to 0.99, 0.60 to 0.99, and 0.55 to 0.87, respectively, and also, the power factor was adjusted from 0.73 to 0.98 during the hardware test. These results show that the designed and constructed automatic power factor correction device works properly.

Keywords: Power Factor, Power Factor Correction, Zero Crossing Detectors, ATmega 328, Capacitor Bank

Abstract: An investigation has been prepared to explore concept of self-similarity and stationarity nature of time series data of a stock market. Two time series data namely the Bombay Stock Exchange (BSE) as well as, the Stock Exchange of Hong-Kong (SEHK), the average parameters have been observed from January 2007 to November 2017. Analysis of both parameters has been carried out, through statistical techniques, to establish the nature of scaling pattern and non-stationarity. The calculation of Hurst exponent done by WVA and VGA showed that the time series is anti- persistent. Augmented Dicky Fuller Test (ADF), Kwiatkowski–Phillips-Schimdt-Shin test (KPSS) and Continuous Wavelet Transform (CWT) have been used to test for non-stationarity.

Keywords: Stock Market; Hurst Exponent; Fractality; Stationarity; Continuous Wavelet Transform

Abstract: Now a day’s electrical equipment’s are more receptive to power quality problems. In power system there may be oscillation in power quality at the sensitive load due to faults and switching operation of breakers. This interruption results in breakdown of the equipment which connected at load side. In this paper, a bidirectional power electronic transformer based three phases four wires Dynamic Voltage Restorer (DVR) structure is projected to inject required series voltage to the electric power system in such a way that continuous sinusoidal voltage is seen at load side at heavy fault occurrences also main power quality problems like voltage sag and swell are deliberate. The PET- Power Electronic Transformer is a power transformer which has the advantage of increasing the frequency to reduce the overall size of transformer and hence this system delivers the extreme cost effective solution to alleviate the above problems which required by customer. So in MATLAB simulation model, this PET based DVR for load side protection against voltage disturbance is investigated which shows that power quality at load side improved with greater controllability and reliability.

Keywords: PET, DVR, SPS, PQ.