Electrical and Electronics

Recently, modular multilevel inverter(MMLI) have gained interest for photovoltaic applications. This topology minimizes the total harmonic distortion both at the DC and AC side and reduces the voltage stress across the devices for high voltage applications compared to the conventional multilevel inverter. This paper explains the significance of a MMLI by employing phase shift PWM technique. This control algorithm is implemented in SPARTAN/FPGA board. The important aspect of this paper is the issues related to capacitor voltage balancing is addressed. The MMLI is powered by PV source and the modeling of PV alongwith MPPT is implemented in MATLAB. The validity of the proposed modular MLI topology is confirmed by simulation and experimentation.

This paper presents a single phase digital prepaid energy meter based on two microcontrollers and a single phase energy meter IC. This digital prepaid energy meter does not have any rotating parts. The energy consumption is calculated using the output pulses of the energy meter chip and the internal counter of microcontroller (ATmega32). A microcontroller (ATtiny13) is used as a smart card and the numbers of units recharged by the consumers are written in it. A relay system has been used which either isolates or establishes the connection between the electrical load and energy meter through the supply mains depending upon the units present in the smart card. Energy consumption (kWh), maximum demand (kW), total unit recharged (kWh) and rest of the units (kWh) are stored in the ATmega32 to ensure the accurate measurement even in the event of an electrical power outage that can be easily read from a 20×4 LCD. As soon as the supply is restored, energy meter restarts with the stored values. A single phase prepaid energy meter prototype has been implemented to provide measurement up to 40A load current and 230V line to neutral voltage. Necessary program for microcontrollers are written in c-language and compiled by Win-AVR libc compiler.

This paper presents a novel method of allocation of capacitor size for a distribution feeder with uncertain load. The interval mathematics is used to perform the power flow solution of radial distribution system. The simulation results have been obtained using the INTLAB Toolbox in MATLAB environment. The standard 15-bus, 10-bus and the 33-bus radial distribution systems which are used by the researchers have been analyzed to demonstrate the effectiveness of the proposed approach. The developed program gives the range of the capacitor ratings in kVAr which could be selected for compensation, corresponding to the min and max limits of the voltages at each bus. For a range of values of capacitor ratings, which when installed at a particular bus results in the range of reduction in cost of capacitor and energy loss reduction. This information is very useful for a distribution system planner.

Voltage instability problems have become important issues in unbalanced distribution networks. In this paper, a new bus positive sequence voltage index of Vcollapse/Vbase-load is introduced to identify the weakest three-phase buses in unbalanced three-phase distribution networks. First, the proposed ranking index is validated based on grid losses and PV curves without and with compensation devices. Then, the index is utilized to place three-phase DG without and with SVC devices at the three-phase weakest buses of the modified IEEE unbalanced 13 node test feeder using the DIgSILENT Power Factory software. Finally, simulation results are presented to show the application of the proposed approach in improving voltage stability and increasing the maximum loading factor under unbalanced loading and/or network conditions.

Electrostatic discharge tester has been designed to measure the electrostatic discharge produced in the woven fabric in terms of kilovolts. Various types of fabrics have been tested for their static properties by using Box-behnken design and their values were analysed based on their influencing parameters such as rubbing cycle, pressure and speed. It is observed that the value obtained by the electrostatic discharge tester varies from cotton, silk and polyester depending upon moisture regain values. It has been found that the maximum static discharge value generated for polyester while testing was 3 kilovolts, which was comparatively higher than cotton (2.1 kilovolts) and for silk(1.8 kilovolts) .The optimum values and their regression, correlation co-efficient were also analyzed.

In this paper, a three layer Small single feed multiband microstrip antenna loaded with slit and two perpendicular shorting posts, is presented. Wide band frequency of operation demonstrated by single geometry, for broadening the bandwidth gap-coupled multi-resonator loaded on the patch, the simulation of proposed design antenna has done by MOM IE3DTM Simulator. The geometry of a single probe fed rectangular microstrip antenna has textured by slit loading and two orthogonal shorting pin on the top layer patch. We have also textured the size of the antenna. This proposed antenna is used for GSM, satellite and wireless communication in, L Band. Achieved 63% reduction of geometrical area of the antenna for L –Band, achieved 57% -10dB impedance bandwidth of L Band.

This paper presents the design and implementation of sharpening of maximally flat cascaded integrator comb compensation filters. Cascaded integrator-comb (CIC) digital filters are computationally efficient implementations of low pass filters. No multiplication characteristic makes them popular in hardware devices. The modified sharpened cascaded integrator comb compensation filter is used to improve magnitude response and gain. For narrow and wide-band compensation second-order and fourth-order linear phase filters are considered. Power-of-two decimation factors of CIC filter is M and number of adders are depends upon decimation factor. Closed form equations for the computation of the filter coefficients are provided. The new technique delivers gain and stop band attenuation correction comparable to existing techniques.

The experiment carried out on voltage and current measurement on TTL logic gates, by the students of electrical and information engineering in the final year of their studies, in the department’s laboratory, which help to understand the voltage and current characteristics of TTL gates and how also how to measure the voltage and current values of TTL gates. This experiment basically shows how voltage and current of TTL gate can be measured. KL- 22001 Basic Electrical/Electronic Circuit lab and KL-26001 Combinational Logic Circuit experiment module are the major equipment used to perform the experiment .These were used because it is much more self-explanatory and easier to work with compared other models. It was discovered that Due to its higher resistance value the LS series, TTL gates have lower input current than the standard series TTL gates. Their output currents are about equal.

In this paper, we present an efficient technique for compression of enhancement layers in scalable video coding (SVC). First we propose an improved interlayer prediction scheme which exploits the inherent redundancy of the underlying Laplacian pyramid with non biorthogonal filters. Secondly we introduce an orthogonal transform in parallel with the current 4x4 transform to improve the coding efficiency of the enhancement layer further. The improved prediction and the transform are implemented in the SVC reference software JSVM 4.0 as additional prediction modes. Experimental results demonstrate coding gains up to 1 dB for I pictures, and up to 0.7 dB for both I and P pictures, over a current implementation.

Electro Magnetic Interference (EMl) emission is always of grave concern for power electronic circuit designers. Due to rapid switching of high current and high voltage, interference emission is a serious problem in switching power circuits. Many products fail to make it to the market because of their failure to comply with the government EMI regulations. Numerous companies have cited EMI problems as the culprit in the delay of their product introduction; a new chaotic pulse width modulation (PWM) scheme is proposed and implemented to reduce the conducted electromagnetic interference (EMI) in power converters. Based on the analysis of constant frequency, Experiments have been made on a power converter. The experiment results show that the EMI spectrum is decided completely by the PWM spectrum, and the chaotic frequency-spreading has an obvious impact on EMI suppressing, compared with the other schemes. To chaoize a frequency-modulated signal which then modulates the carrier frequency. The proposed scheme not only suppresses the peaky EMI, but also avoids the occurrence of low-order noises and mechanical resonance.