Department of Electrical Engineering

Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

In Real-Time analysis of distribution networks, it is essential to correctly represent the as is network status in the field. This includes identification of Energized/De-energized nodes, Energized/De-energized branches, loops, parallels and temporary modifications. Although distribution networks are normally operated radially, a distribution system undergoes several configuration changes topologically in daily operations where, loops and/or parallels may be intentionally or inadvertently created. This paper proposes a novel and practical approach for the formation of the Branch Node Matrix for balanced as well as unbalanced 3-pH networks. The Branch Node Matrix is initially formed for the base network and then updated based on several conditions using the Breadth-First Search algorithm. Identification of specific network topology conditions, based on the Branch Node Matrix, is explained using the above-mentioned approach. Identification of such topological conditions serves the utilities to represent the network correctly and obtain accurate power flow results. Additionally, it may warn the system operators of the existing abnormal topological conditions and to take remedial steps proactively. © 2023 Elsevier B.V.

World University root node

Electric Power Systems Research

A practical approach to real-time network topology processing in a radial distribution system

The letter presents a method of frequency to time domain conversion of Scattering Parameter data for microwave imaging applications. The time to frequency domain conversion was initially tested in the MATLAB. The testing was conducted in a realistic microwave imaging environment with an antenna and a heterogeneous breast phantom. Note that, the time domain signal obtained from the Vector Network Analyzer (VNA) as well as the time domain signal obtained with the introduced process is similar indicating efficiency of the proposed method. An ultra-wideband (UWB) signal is transmitted from the transmitting Antipodal Vivaldi Antenna to the breast phantom and the received signals are collected by the same antenna over a monostatic process. A total of 36 antenna rotations were considered while scanning the phantom from various orientations. All the data stored in the VNA is extracted and the proposed frequency to time domain conversion technique was applied to it. Finally, the Delay and Sum beamforming algoirithm was used to reconstruct the target image. © 2024 Wiley Periodicals LLC.

Microwave and Optical Technology Letters

Monostatic microwave imaging of cancerous breast phantom with a frequency to time domain conversion technique

The potential impacts of the inverter-interfaced renewable energy resources (IIRERs) on the performance of sequence-based directional relaying schemes (SBDRS) have been investigated in this paper. The directional overcurrent relays such as 67POS, 67NEG, 67ZERO and 32Q have been considered for the investigation. CIGRE-14 bus system with IIRERs along with detailed modeling of inverter control scheme (with and without grid codes) and SBDRS have been done in the PSCAD environment. The mathematical analysis and circuit realization of the IIRERs have been attempted in the paper. The exclusive fault characteristics exhibited by IIRERs cause the conventional SBDRS to mal-operate. Significant change in levels of sequence currents and angular relationships between sequence voltages and currents during faults contributes to relay's unpredictable behavior. The comparative study based on different fault types, fault resistances and interconnecting transformer connections have also been done. The study reveals the impact of non-generalized angular differences between positive sequence voltage and current at the inverter terminal on performance of 67POS. It is found that 67NEG and 32Q mal-operated for all types of unbalanced faults while the 67ZERO can be utilized for grounded fault with delta-star grounded connection of interconnecting transformer. © 2023 Elsevier B.V.

Exploring the interdependence between control and protection philosophies in inverter integrated power system: A case study on directional relaying schemes

The architecture of solid-state transformers (SSTs) is usually comprised with three-stage cascaded converters. The control of cascaded multistage SSTs is conventionally designed considering decoupled stages. Furthermore, the isolating stage, which is typically implemented with dual active bridge converters, employs a closed-loop control with a much larger bandwidth (BW) than the ac-dc stage. This disparity in the BWs can put a strain on the intermediate dc-link capacitors that connect the ac-dc and isolating stages, resulting in large capacitor voltage excursions when the load changes. In fact, this can result in ac-dc stage overmodulation and even large current overshoots through the isolating stage's high-frequency transformers. This necessitates advanced SST control strategies that can mitigate the aforementioned challenges. This article proposes a control design in which the state variables are selected as the sum of capacitor energies and differences in capacitor energies. Unlike the state-of-the-art SST controllers, the proposed integrated control approach creates a more balanced and safe distribution of energies among the dc-link capacitors during load transients. The control design is simplified as the difference in the control-loop BWs between the stages does not affect this disturbance attenuation ability. The effectiveness of the proposed control is demonstrated by experiments using a 1-kVA SST with two strings. © 1986-2012 IEEE.

IEEE Transactions on Power Electronics

A Control Strategy for Solid-State Transformers with Coupled Load Disturbance Attenuation Ability

By considering the resource-constrained affordable wearable or portable health monitoring devices, in this paper, we present a lightweight digital compressed ECG sensing with recognition of fast/slow and regular/irregular heartbeat patterns by using beat-to-beat intervals (BBIs) directly computed from compressed sensing (CS) measurements without ECG reconstruction process. For extracting BBIs, we presented a fast straightforward R-peak detection method in the CS domain without using sets of search-back detection rules unlike other methods. On the standard MIT-BIH arrhythmia database, the CS-ECG based R-peak detection method had an average accuracy of 99.47% with false positives of 381 beats and false negatives of 195 beats for a total of 109021 beats. The CS-ECG based HR classification method, with three classes of bradycardia, tachycardia and normal, had an accuracy of 96.75%, 91.18% and 99.02% based on the feature of number of BBIs and an accuracy of 95.64%, 82.35% and 98.81% based on the feature of average BBIs. The CS-ECG based regular/irregular rhythm (RIR) recognition method had a sensitivity (SE) of 93.17%, specificity (SP) of 96.87% and accuracy (ACC) of 94.83% based on the variation between the BBIs that are determined by comparing the difference between the successive BBIs with a predefined BBI threshold. The proposed method can reduce computational resources and energy reduction of 75% with the CS-based data reduction factor of 4 that has a great potential in energy-efficiency of battery operated wearable devices in long-term continuous health monitoring environments. © 2023 IEEE.

15th International Conference on Electronics, Computers and Artificial Intelligence, ECAI 2023 - Proceedings

Compressed ECG Sensing Based Fast/Slow HR and Regular/Irregular Rhythm Recognition for Resource-Constrained Health Monitoring Devices

Photoplethysmography (PPG) signals play an important role for automatic measurement of pulse rate, blood pressure, non-invasive blood glucose level and respiration rate. Most of the PPG monitoring devices are prone to motion artifacts and noises under different PPG recording conditions. Thus, automatic assessment of PPG signal quality is most essential for discarding unacceptable PPG signals and reducing false alarms due to the noisy measurements. This paper presents a new PPG signal quality assessment (SQA) method by using the average degree feature extracted from the horizontal visibility graph (HVG) of the PPG signal and six different classifiers such as random forest (RF), Naive Bayes (NB), decision tree (DT), support vector machine (SVM), multilayer perceptron (MLP), convolutional neural network (CNN). On a wide variety of standard databases, evaluation results show that the CNN based SQA method had an overall accuracy of 99.24% that outperforms other five SQA methods in terms of overall accuracy. The NB based SQA method had an accuracy of 99.21% with lower memory space of 1 kB as compared to other SQA methods. © 2023 IEEE.

Graph Signal Processing Based Classification of Noisy and Clean PPG Signals Using Machine Learning Classifiers for Intelligent Health Monitor

For microwave head imaging, a patch in the shape of a flower is created in this work using the CST Studio software. A matching performance of more than 10 dB is achieved between 1.59 to 5.2 GHz for the specified structure. When operating at 4.4 GHz, the antenna achieves an apex gain of 3.92 dBi. To determine the impact of the antenna on the human head, the SAR value of the designed antenna is examined. 7-layered human head model designed on software is used for this. The simulator is used to study each performance criterion for the proposed structure. Additionally, 11 copies of the intended antenna are positioned all around the designed head model to obtain sufficient data for imaging the embedded tumour. © 2023 IEEE.

International Conference on Microwave, Antenna and Communication, MAC 2023

Microwave Medical Imaging using a Compact Monopole Antenna for Brain Tumor Detection

Frequency selective surface (FSS) gains significant interest in the wireless communication system for shielding against electromagnetic interference (EMI). This paper presents a novel multiband 2.5 D FSS with dual operations in the transmission and reflection modes. The FSS exhibits dual-band bandstop filtering in transmission mode to shield EMI at sub-6 GHz 5G, WLAN and WiMAX frequencies. In the proposed multilayer geometry, two stopband (SB) resonances (at 2.32 and 4.04 GHz) are generated using enhanced capacitance loaded modified Jerusalem cross (EC-MJC) and via connected meandered square loop (VC-MSL). FSS transmits the signal with a low insertion loss of &#x003C; 0.6 dB at pass-band frequency (2.98 GHz), existing between two reflection bands. The miniaturized unit cell size (&#x003C; 0.07 &#x03BB;L), polarization insensitive, and highly stable filter response at almost all incidence angles (up to 80&#x00B0;) are the attractive features of the designed FSS. In reflection mode, the 2.5 D FSS has been configured for multiband microwave absorbers at dual, triple, and quad-band resonances. The FSS and absorber are practically realized for the experimental validation of simulation results. The measured results are in good accordance with the numerical simulation for both operating modes, which establishes the design principle of the multifunctional FSS. IEEE

IEEE Transactions on Antennas and Propagation

Miniaturized Near All Angle Stable 2.5D FSS For Dual Band Shielding in Transmission Mode and Multiband Absorption in Reflection Mode

This work demonstrates a novel, reflective-type, dual-polarized multiband polarization transformer for various C to Ku band applications. The design constitutes a top FSS printed on a thin FR-4 grounded dielectric substrate. A y/x-polarized incident wave experiences linear-circular conversion from 4.61 to 4.71 GHz (right-hand circular polarized (RHCP)/left-hand circular polarized (LHCP)), 5.44 to 7.68 GHz (LHCP/RHCP), 10.13 to 14.98 GHz (RHCP/LHCP), and 16.68 to 17.19 GHz (LHCP/RHCP) with 3.41, 34.15, 38.63, and 3.01% FBW, respectively. In addition, it performs linear-cross conversions with a minimum 90% polarization conversion ratio (PCR) from 4.92 to 5.18 GHz, 8.32 to 9.41 GHz, and 15.56 to 16.25 GHz with 5.15, 12.30, and 4.34% FBW. Multiple surface plasmonic resonances are responsible for these polarization conversions in different bands. The device performance is angular stable for both transverse electric (TE) and transverse magnetic (TM) incidences. The design novelty lies in compacted periodicity 0.112λL, low-profile thickness 0.037λL with a multi-conversion (switching the orthogonal circular rotation in consecutive bands), and stable angular response, which can potentially be used in real-time applications. © The Author(s), 2022. Published by Cambridge University Press in association with the European Microwave Association.

International Journal of Microwave and Wireless Technologies

Novel miniaturized arrow linked figure of eight square loop FSS-based multiband linear-circular and linear-cross reflective microwave polarizer

In this research, a novel multi-band reflecting polarization converter is proposed, which uses a single-layered substrate to convert between linear and circular polarization. The top FSS printed on the grounded dielectric spacer comprises an I-shaped metallic patch and an orthogonally connected inductive grid. For the y-polarized EM wave incidence, the design shows linear-cross polarization rotation with a Polarization Conversion Ratio (PCR) of a minimum of 90% from 15.28–17.86 GHz, 39.53–44.46 GHz, 55.46–56.26 GHz with 15.57%, 11.74%, and 1.43% Fractional Bandwidth (FBW). In addition, it also experiences linear-circular conversion with 3 dB minimum Axial Ratio (AR) from 12.06–14.04 GHz, 19.96–36.34 GHz, 47.08–54.74 GHz, and 56.60–57.06 GHz with 15.17%, 58.19%, 15.05%, and 0.81% FBW. Various oblique incidences in the design are studied, and the performance is stable up to 45°. Next, the proposed design is shorted at the end, replicating the diode ON condition mechanically, turning the proposed design into a perfect reflector in the operating range. The unitcell architecture is compact with a periodicity of 0.101 × 0.076 λL2, and overall thickness of 0.064 λL. The authors are certain that the design's small size and excellent angular stability make it ideal for applications calling for reflective type multi-band dual-polarized linear-circular and linear-cross polarization conversion, including reflector response. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Lecture Notes in Electrical Engineering

Multi-band Dual-Polarized Linear-Circular and Linear-Cross Obliquely Stable Reflective Type Polarizer with Mechanically Tunable Reflector Response for K-and Ka-Bands Applications