April'19

The IUP Journal of Electrical and Electronics Engineering

Focus

Orthogonal Frequency Division Multiplexing (OFDM) is an advanced modulationtechnique used in fourth-generation wireless communication. High Peak to Average Power Ratio (PAPR) is a drawback affecting the performance of OFDM communication. In the paper, “PAPR of QPSK OFDM Modulation Schemes: A Comparative Study”, by M Vasantha Lakshmi and B Kanmani, a comparison of PAPR of Quadrature Phase Shift Keying (QPSK) and Offset QPSK has been made. It is reported that there is a reduction in the mean with the Offset QPSK compared with the QPSK.

Active Power Filters (APF) are used to mitigate harmonic problems caused by switching power supplies, arc furnaces, etc., in power distribution systems. In the paper, “Active Power Filters to Reduce Harmonics and Improve Power Quality” by Prakash L Chavan and Sanjeev K Nayak, a hybrid active power filter is proposed for compensation of harmonics to improve power quality. The hybrid filter uses a combination of passive filter and shunt APF to eliminate both higher and lower order harmonics. The p-q method is used for harmonic suppression.

An adiabatic process is one in which the total heat or energy in the system remains constant. Adiabatic circuits implement reversible logic and reduce energy dissipation. In the paper, “Design and Performance Analysis of Mux Using ECRL, MERL and PFAL”, the authors, Raman and Ramnish Kumar, have analyzed the performance of 2:1 multiplexer circuits using various energy recovery logics like Efficient Charge Recovery Logic (ECRL), Modified Energy Recovery Logic (MERL), Positive-Feedback Adiabatic Logic (PFAL) and Advance Energy Recovery Logic (AERL). Various parameters like number of transistors, maximum operating frequency, pulse width, slew rate, etc. are studied.

Dielectric Resonator Antenna (DRA) has attractive features like compact size, lightweight, low metallic losses, high radiation efficiency, wide bandwidth and low cost. DRAs are available in different shapes, and triangular-shaped DRAs occupy smaller area than any other DRA for given resonant frequency and variable aspect ratios. In the paper, “A Triangular Dielectric Resonator Antenna for Wi-Fi Applications” by Renuka Makwana and Prarthan Mehta, implementation of a microstrip fed Triangular DRA (TDRA) for 2.45 GHz frequency using Alumina as Dielectric Resonator is presented. The fabricated antenna is suitable for 2.4 GHz operated Wi-Fi and other wireless applications.

There are two types of induction generators widely used in wind power systems—Squirrel-Cage Induction Generator (SCIG) and Doubly-Fed Induction Generator (DFIG). The major problem with SCIG wind system is its reactive power consumption. In the paper, “PMSG Synchronization with IG Using MATLAB Simulation for LVRT Augmentation” by Abhishek M Patel and Shruti Khatri, a Permanent Magnet Synchronous Generator (PMSG) is proposed to be connected to SCIG to improve voltage profile and provide Low Voltage Ride Through (LVRT) capability as required by the Indian Grid Code.

SEN Transformer (ST), a three-phase transformer equipped with on load tap changer, can be used to control amplitude and phase angle of sending-end bus voltage in power system. The paper, “Capability of SEN Transformer in Low Frequency Oscillation Damping” by Nemat Talebi, Behzad Taghizadeh and Bala Subramanyam, shows that ST can be used in power systems to dampen low frequency oscillations. The power system model used for the study is a Single Machine Infinite-Bus (SMIB) system with Static VAR Compensator (SVC), Controllable Series Compensation (CSC) and Phase Shifter (PS).

- MSR Murty
Consulting Editor

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Article   Price (₹) Buy
PAPR of QPSK OFDM Modulation Schemes: A Comparative Study
50
Active Power Filters to Reduce Harmonics and Improve Power Quality
50
Design and Performance Analysis of Mux Using ECRL, MERL and PFAL
50
A Triangular Dielectric Resonator Antenna for Wi-Fi Applications
50
PMSG Synchronization with IG Using MATLAB Simulation for LVRT Augmentation
50
Capability of SEN Transformer in Low Frequency Oscillation Damping
50
       
Contents : (April'19)

PAPR of QPSK OFDM Modulation Schemes: A Comparative Study
M Vasantha Lakshmi and B Kanmani

With the rapid growth in the field of telecommunication, there is a huge demand for increase in the bandwidth. Orthogonal Frequency Division Multiplexing (OFDM) is an advanced modulation technique suitable for the fourth-generation wireless communication due to the improved spectral efficiency and bandwidth. Besides these benefits of the OFDM, there are some major concerns which need to be taken care. Inter-symbol interference and the Peak to Average Power Ratio (PAPR) are the major drawbacks affecting the performance of the OFDM symbols. In this paper, a comparative study of PAPR of Quadrature Phase Shift Keying (QPSK) OFDM and the Offset QPSK OFDM has been done. Initially, OFDM symbols are generated with QPSK as the modulation techniques for the different symbol lengths ranging from 8 to 12 and the PAPR has been calculated for all combinations. The number of combinations resulting in a high value of PAPR was 16 for all the symbol lengths. The experiment was repeated with the offset QPSK for the same symbol lengths and the number of combinations resulting in a high value of PAPR was reduced to 8 for all symbol lengths. The mean of the QPSK and the Offset QPSK was computed. There was a reduction in the mean with the offset QPSK compared with the QPSK. The simulation results and the mean of the same have been discussed.


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Active Power Filters to Reduce Harmonics and Improve Power Quality
Simmi Garg, Anuj Kumar Sharma and Anand Kumar Tyagi

The paper focuses on the implementation of Hybrid Active Power Filter (HAPF) to compensate harmonics and improve power quality. Development in smart grid technology created a higher demand for improved power quality. Harmonics are the main constraints for poor power quality. Adjustable-speed drives, switching power supplies, arc furnaces, electronic fluorescent lamp ballasts, lightning strike and L-G fault are the sources of poor power quality. Nonlinear loads are the major source of harmonics in modern power system. The problems associated with power quality are voltage sags, voltage swells, interruption, sustained interruptions, overvoltage, undervoltage, long-duration voltage variations, voltage imbalance and waveform distortion. To overcome these problems, it is motivated to design the HAPF. For power quality improvement, hybrid filter has better filtering properties as it eliminates both high and low order harmonics. The p-q method is used for harmonic suppression. The expected properties of shunt hybrid power filter have been confirmed by simulation test in MATLAB/Simulink.


© 2019 IUP. All Rights Reserved.

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Design and Performance Analysis of Mux Using ECRL, MERL and PFAL
Raman and Ramnish Kumar

The paper compares three adiabatic logic designs like Efficient Charge Recovery Logic (ECRL), Modified Energy Recovery Logic (MERL) and Positive Feedback Adiabatic Logic (PFAL). A 2:1 multiplexer is implemented using these design techniques and the results are compared in terms of rise time, fall time, transistor count, delay, slew rate, etc. The designed circuits are simulated using mentor graphics VLSI design software Pyxis _v10.5_5_201606075. From the results, it is found that the delay of PFAL-based circuits is better compared to ECRL and MERL.


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Article Price : Rs.50

A Triangular Dielectric Resonator Antenna for Wi-Fi Applications
Renuka Makwana and Prarthan Mehta

The paper proposes a microstrip-fed Triangular Dielectric Resonator Antenna (TDRA) for 2.45 GHz frequency. Alumina is used as dielectric resonator having dielectric constant (er) of 9.8. The microstrip coplanar loop feeding mechanism is etched on the topside of FR402 substrate and dielectric resonator is placed on it. The proposed geometry achieves the return loss |s11| < –10 dB from 2.41 GHz to 2.52 GHz. The experimental results showed peak gain of 5.6 dBi at 2.46 GHz resonance frequency. The measured results are well in agreement with simulated results.


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PMSG Synchronization with IG Using MATLAB Simulation for LVRT Augmentation
Abhishek M Patel and Shruti Khatri

The Induction Generator (IG) wind turbine system uses Fixed Speed Wind Turbine (FSWT) system. Due to high dependence on reactive power, it bears achieving new wind grid code requirements. IG requires high reactive power during network disturbances. Nowadays, Flexible AC Transmission System (FACTS) devices are available in the market for compensation of reactive power of IG during network faults. The use of FACTS devices in wind system increases the total budget. So, we have to concentrate on new innovative kind of topology which is cost-effective and gives the exact solution to the problem. The new idea is to locate the Permanent Magnet Synchronous Generator (PMSG) near to IG and connect via underground cable at Power Cable Connects (PCC). It has the ability to fulfill the requirements of reactive power during network disturbances. When there is a fault on network reactive power, requirement of IG is fulfilled using a combination of it with PMSG to meet wind grid code requirement. Low Voltage Ride Through (LVRT) or fault ride through characteristic of FSWT IG is analyzed using Indian grid code. The simulation results clearly showed that the proposed topology might be a good solution to augment the LVRT requirement of fixed speed Wind Turbine Generating System (WTGS) and for achieving certain optimal operating performance and economic benefits. The proposed topology illustrates the defined reactive power and voltage retort, which maintains the FSWT IG system-based wind farm to ride through the grid fault without installation of any additional devices.


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Capability of SEN Transformer in Low Frequency Oscillation Damping
Nemat Talebi, Behzad Taghizadeh and Bala Subramanyam

FACTS devices are important in controlling power in a line and voltage amplitude at steady state and dynamic conditions. They perform well in suppressing power system oscillations while improving the damping and are based on power electronics technology supported by advanced control techniques. The paper proposes a new device SEN Transformer (ST) to damp Low Frequency Oscillations (LFOs) considering the techno-economic feasibility. ST has conventional technology of transformers and tap changer settings. The operational speed of tap changer switching determines the response time of damping controller, which is quite adequate (with simple electronic switches) in most utility applications.


© 2019 IUP. All Rights Reserved.

Article Price : Rs.50

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