Sisir Nayak

Sisir Nayak
Indian Institute of Technology Guwahati | IIT Guwahati

About

153
Publications
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1,208
Citations

Publications

Publications (153)
Article
This study investigates the influence of accelerated thermal ageing and degradation on the breakdown strength of natural ester oil (NEO-FR3) compared to mineral oil (MO) under DC voltage stresses. The base oils undergo accelerated thermal stresses over extended ageing periods of 90, 200, and 500 hours. The primary focus is to understand the breakdo...
Patent
Full-text available
The present invention offers a portable, shielded test chamber for accurately measuring partial discharges (PD) in liquid and solid insulation materials used in electrical transformers. Designed to overcome the limitations of traditional testing methods that require extensive laboratory setups, this portable chamber facilitates on-site, real-time d...
Conference Paper
This research delves into the degradation study of oxidative ageing on pressboard insulation immersed in mineral oil (MO) and natural ester oil (NEO-FR3). It comprehensively evaluates the non-immersed pressboard, fresh MO and NEO immersed pressboard samples, and their oxidatively aged samples post 90, 200 and 500 hours. The assessment of the pressb...
Patent
Full-text available
The effect of multiple stresses in the transformer oil leads to the chemical degradation in it and in due course of time, the whole insulation system breaks down. It is very difficult to ascertain the quality of the used oil in the transformer unless continuous monitoring of electrical and thermophysical characteristics. Therefore, in this innovati...
Patent
Full-text available
The streamer characteristics and breakdown strength along the surface of solid insulation immersed in liquid dielectrics under high voltage stresses are studied by product design engineers, scientists and researchers in industries to develop a reliable and efficient material for high voltage liquid filled power apparatus. The present invention gene...
Patent
Full-text available
A system and method for condition assessment of transformer liquid insulation. The claimed system includes a portable anechoic chamber with electromagnetic signal absorbers for avoiding external noise and internal reflection of incident electromagnetic waves The said anechoic chamber houses a Vector Network Analyzer (VNA) connected to a s-band pyra...
Article
Gases are generated in the liquid insulation during its decomposition caused by thermal and/or electrical faults. The generated gases dissolve in the oil and their measure play an important role in predicting the nature of the fault. With the advent of mixed insulating oils as potential alternative to the mineral oil, there is a need to study the g...
Article
This letter presents a novel random forest regression (RFR) based machine learning (ML) method for predicting the radiation properties of a planar metasurface reflector (PMSR) antenna. The extracted parameters of PMSR at 2.45 GHz serve as input for the RFR model for training on power flows and radiation properties. For comparison, an experiment wit...
Article
This article derives a new explicit expression of current of a double-diode model (DDM) photovoltaic (PV) module from the implicit current-voltage (I-V) expression. Here, the exponential term of the I-V expression of a DDM PV module is represented by Taylor series. The validation is done on the implicit I-V expression with the derived quartic I-V e...
Article
Full-text available
Partial shading in photovoltaic (PV) array causes mismatch loss and reduces power output. To dilute the concentration of partial shading effect on the array, a novel module relocation technique (MRT) is proposed to improve the power output of the partially shaded PV array. In this proposed technique, the physical position of the modules in totally...
Article
The transformer consists of solid and liquid insulation working in conjunction for its efficient and coherent performance. With the advent of bio-degradable natural ester oils as insulants, the utilities and manufacturers are shifting towards retrofilling the old transformers and initiatory filling the new transformers with these ester oils. This s...
Article
The developments in the research and design of HVDC transmission equipment prompted this investigation into determining the electrical strength of insulating oil under DC voltage stresses. The manufacturers of oil-filled high-voltage equipment are continually tasked with developing novel insulating liquids with high dielectric strength, efficient h...
Patent
Full-text available
The present invention generally relates to a planar meta-surface sub-reflector based Cassegrain reflector system for transferring and harvesting of power and energy comprises a horn antenna extending to a boresight axis having an aperture of an asymmetric shape when view along the boresight axis and configured to radiate power at 2.45GHz. a parabol...
Patent
Full-text available
The electric field enhancement system for automated mobile vehicle charging comprises a horn antenna(1) coupled to a magnetron to receive power through a horn antenna feeder; a receiving antenna array(4) mounted on an automated mobile vehicle (3) connected with a receiving antenna feeder(5), wherein a metamaterial lens(2) is placed between the horn...
Patent
Full-text available
The streamer characteristics and breakdown strength of liquid insulation under high voltage stresses are studied by product design engineers, scientists and researchers in industries to develop a reliable and efficient material for high voltage liquid filled power apparatus. The present invention generally relates to an apparatus for analyzing brea...
Article
This paper presents a novel planar metasurface subreflector (MSSR) array-based dual-reflector antenna inspired by Cassegrain arrangement for simultaneous beaming in far-field microwave wireless power transfer at f0=2.45 GHz for the first time. The MSSR unit cell exhibits 94.8% reflection and 0.0065λ0 thin geometry where λ0=122.45mm is the operating...
Article
Removal of excess moisture from transformer oil (TO) is vital for the trouble-free operation of the transformer. Conventional oil filtration by dehydrating with heat and vacuum is a time-consuming method and mostly requires the shutdown of the transformer. Developing an efficient online desiccant for TO has significant operational and economic adva...
Article
Full-text available
The purpose of this present study is to prepare a stable mineral-oil (MO)-based nanofluid (NF) for usage as a coolant in a transformer. Nanoparticles (NPs) such as hexagonal boron nitride (h-BN) and titanium oxide (TiO2) have superior thermal and electrical characteristics. Their dispersion into MO is likely to elevate the electrothermal properties...
Article
The insulation system in a transformer degrades over time and it needs periodic monitoring for uninterrupted operation of the power system network. Moisture content (MC), acid number, and dissolved gases are the important parameters that establish the aging and degradation status of the transformer liquid insulation. This work focuses on using high...
Patent
The insulating oil in medium, high, extra high, and ultra-high voltage equipment such as transformer carry an equivalent role as solid insulation in reliable operation of the equipment. The insulating oil ages with time due to multiple stresses. The electrical, thermal and chemical properties of the aged oil degrade and in turn result in failure of...
Article
Full-text available
This article presents the design of a compact microstrip-fed triple-band slot antenna for WLAN/WiMAX/C-band downlink satellite communications. The newly designed proposed simple structure has a considerably high-center frequency ratio and can significantly suppress cross-polarization levels. This antenna consists of a double annular-ring slot (DARS...
Article
Full-text available
This article presents the design and characterization of a dual-band, compact, and dual-circularly polarized (CP) traveling wave series-fed circular slit microstrip array (TWSCSMA) antenna operating in quad-band CP at 2.5/3.5/3.8 GHz WiMAX and 5.2 GHz WLAN applications. The radiating structure consists of an annular ring traveling wave series-fed c...
Article
Nanofluids with their superior electrical and thermal properties are a promising alternate liquid dielectric in power transformers. Alongside the electric field, magnetic field is also an integral part of power transformers. It accounts for power transfer through flux linkages and due to the design constraints, flux leakages exist in every transfor...
Patent
Full-text available
A parabolic profile pyramidal horn antenna with flaring in both the E- and H-plane is presented in this study. The proposed structure having aperture dimensions of 518.10 × 408.36 mm2 is designed and fabricated for S-band (2.2–3.3 GHz). Due to increase in the flaring by 3.35° in the E-plane and 3.18° in the H- plane compared to the optimal typical...
Chapter
The main focus of this chapter is the processing of the natural ester-based oils to be used as an insulating liquid in a transformer and other electrical apparatus. Natural esters are eco-friendly alternatives obtained from renewable resources such as plant seeds. These natural oils are composed of triglycerides, which react with alcohol to produce...
Article
In this work, a non-edible natural ester oil (NEO) is considered for the study of its ageing characteristics by the frequency domain spectroscopy (FDS). The NEO considered is the Jatropha Curcas oil (JAT) because of its non-edible and biodegradable nature. The FDS method is a non-destructive measurement technique which is used to analyze the charac...
Article
An important element of the power system network is the transformer. The conventional mineral oil (MO), which acts as an insulation and heat transfer agent in a transformer plays a major role in its steadfast operation. The insulation is highly stressed during its operational lifetime. Thus, alternative insulating liquids are being studied to enhan...
Article
In the existing solar photovoltaic modules, cells are connected in series. The performance of the series-connected module degrades severely during partial shading condition. Further, the use of bypass diode causes multiple peak (local and global peaks) problem. Therefore, total cross tied (TCT) connection has been proposed in this paper to connect...
Conference Paper
Transformer is the most important equipment in a power system network. Thermal and electrical stresses are the major cause of concerns for failures in a power transformer. These stresses are sustained by mineral oil (MO) which provides insulation as well as acts as a coolant in the transformer. MO is extensively used in power transformers for insul...
Article
A graded refractive index metamaterial (MM) exhibits a magnetic dipole designed and demonstrated experimentally for 2.45 GHz operating frequency. The system efficiency of the far-field wireless power transfer technique increased to 32.6% with MM. With 16° reduction in half power beamwidths, 9.78 dBm is received at 1 m with 30 dBm input when MM is p...
Article
Full-text available
Wind power generation is observing a significant use of doubly-fed induction generator (DFIG) due to its improved efficiency, but the converter used in the configuration is sensitive to the presence of a fault in the grid. This paper presents a fault ride-through (FRT) configuration, which includes a thyristor-based bridge-type non-superconducting...
Article
Full-text available
This paper presents an aperture matched parabolic pyramid horn antenna (APPHA) having flaring in the E‐ and H‐ plane. The proposed structure is designed and manufactured for S‐band (2.2–3.3 GHz) with a semicircular aperture matched section in both planes. The APPHA gives half power beam width (HPBW) less than 17° and 15° in the E‐ and H‐ planes, re...
Article
In this paper, the maximum power point (MPP) of a photovoltaic (PV) source is estimated using the proposed explicit current-voltage (I- V) expression. The conversion of implicit expression of current to explicit expression of I-V equation is carried out using Maclaurin series expansion. The explicit I-V function of the PV module is validated with t...
Preprint
Full-text available
This article presents a structure of coplanar waveguide (CPW)-fed star-shaped monopole antenna (SSMA) with a pair of quarter-circular-slit (QCS) and partly-hexagonal-ring-slit (PHRS) defected ground structure. By inserting a pair of QCS and PHRS on the rectangular ground plane, an excellent impedance bandwidth is achieved i.e., 139 % (from 2.2--12....
Article
Full-text available
Abstract The effective implementation of battery management system (BMS) in various applications such as electric vehicles (EVs), renewable energy sources (RES) integrated smart‐grids and micro‐grids, necessitates accurate estimation of the battery parameters and states. This paper primarily focuses on offering an improved solution to the state of...
Conference Paper
Full-text available
An important element of the power system network is the transformer. The conventional mineral oil (MO), which acts as an insulation and heat transfer agent in a transformer plays a major role in its steadfast operation. The insulation is highly stressed during its operational lifetime. Thus, alternative insulating liquids are being studied to enhan...
Article
To increase lifespan and optimize capacity utilization of lithium-ion (Li-ion) battery, it is imperative to predict its states accurately. This paper primarily focuses on offering an improved solution for estimating one of the most important battery states known as state of charge (SOC). After extensive analysis of the current state-of-the-art meth...
Article
The application of nanofluids (NFs) in power apparatus is increasing in the recent years because of its higher dielectric strength, higher thermal conductivity, lower electrical conductivity and lower dissipation factor. The reason for increase in the dielectric strength of the NFs over base oil is due to the electron scavenging by the nanoparticle...
Presentation
Full-text available
The presentation is about the use of metamaterial in space solar power projects.
Article
Full-text available
This paper aims at investigating the dissolved gas analysis (DGA) and long-term performance of Environtemp (FR3) and Jatropha Curcas oil (JAT). Thermal stress is applied to both oils in a sealed setup at 150 o C for up to 2000 hours and samples are removed and tested at 500 hour intervals. It is observed that FR3 is more prone to stray gassing as c...
Chapter
Full-text available
This paper investigates the unsteady aerodynamic performance due to oscillatory motion. The wind flows velocity is constant across the wind turbine rotor is applied, therefore, the attached flow on a 2-D airfoil and the aerodynamic critical damping of the large-scale horizontal axis wind turbine (LS-HAWT) blade structure are considered. The blade e...
Article
Full-text available
A study has been performed to extract the unknown parameters of a photovoltaic (PV) module using mathematical model-driven analysis. Neglecting the less significant terms, the number of non-linear exponential terms are reduced to develop a simplified algorithm to estimate five unknown parameters such as diode ideality factor, series resistance, shu...
Conference Paper
A parabolic dish reflector (PDR) is designed and fabricated to convert the plane wave to spherical wave at the focus. The performance of PDR made from aluminum and Polydimethylsiloxane (PDMS) coated with aluminum is carried out. It is observed that the performance of the PDR made from PDMS is same as that made from aluminum, thus the proposed PDR m...
Article
Full-text available
Nanofluids (NFs) are an emerging technology in the field of dielectrics. These oils are used in transformers and other power apparatus for the purpose of insulation and cooling. The vegetable oil (VO) proposed in this paper is the Pongamia pinnata oil (PPO), commonly known as karanji oil. The molecular structure of PPO is changed by the transesteri...
Article
Full-text available
Estimation of the output power of a solar photovoltaic (PV) system during partial shading condition (PSC) is an interest of PV installers. Owing to the inclusion of a bypass diode, the occurrence of local and global maximum peak creates more difficulty in the calculation of maximum power output from a PV array. In this study, a mathematical model i...
Conference Paper
This article shows the frequency tuning using PIN diode of transmission type digital metasurface. Here, the S21 amplitude of the unit cell in ON and OFF condition of PIN diode is given the digital code of “0” when the S21 value is less than - 8 dB, and “1” when the amplitude is 0 dB. It is observed that when the diode is ON, the 10 x 18 array shows...
Conference Paper
A square slotted patch antenna for far-field wireless power transfer applications is presented. The antenna has compact size equal to 0.416�0.236�0.013� which can be fit into most of the devices. It exhibits a total of 780 MHz of -10 dB impedance bandwidth in S-band with good directional characteristics. A maximum of 1.24 dB gain is observed with 1...
Conference Paper
In this paper, the efficient modeling of DC-RF module of space solar power satellite (SSPS) with improved antenna design and metasurface is proposed. With the higher losses as one of the present problem in the DC-RF conversion, using single-phase full-bridge topology with a maximum power point tracking algorithm is proposed. The design parameters o...
Article
Full-text available
Estimation of the output power of a solar photovoltaic (PV) system during partial shading condition (PSC) is an interest of PV installers. Due to the inclusion of a bypass diode, the occurrence of local and global maximum peak creates more difficulty in the calculation of maximum power output from a PV array. In this paper, a mathematical model is...
Patent
This invention is about designing an aperture matched parabolic pyramidal horn antenna (APPHA) to achieve the higher values of gain, half power beam width, and front-to-back ratio than typical pyramidal horn antenna with equal aperture area. The parabolic tapering concentrates radiating field in the propagating direction to great extent to have hig...
Patent
This invention is about transferring/harvesting the power/energy to/at the receiver end by using metamaterials for manned/unmanned applications. The WPT/WEH techniques used nowadays are having less efficiency and small distance coverage. Furthermore, its performance degrades as the transmitting antennasradiated electromagnetic waves that carries po...
Article
Full-text available
A parabolic profile pyramidal horn antenna with flaring in both the E- and H-plane is presented in this study. The proposed structure having aperture dimensions of 518.10 × 408.36 mm2 is designed and fabricated for S-band (2.2–3.3 GHz). Due to increase in the flaring by 3.35° in the E-plane and 3.18° 3.18° in the H- plane compared to the optimal ty...