Faculty Publications
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Item Analysis and experimental testing of a built-up composite cross arm in a transmission line tower for mechanical performance(2013) Selvaraj, M.; Kulkarni, S.; Ramesh Babu, R.This paper discusses the development of a composite cross arm for a power transmission line tower using FRP pultruded profiles. The mechanical performance of the composite cross arm has been evaluated using experimental testing and an analytical solution as well as a finite element simulation. By using the composite cross arm in place of a steel cross arm with ceramic insulators, considerable reduction of transmission corridor is achieved. © 2012 Elsevier Ltd.Item Effects of the Reynolds number on two-dimensional dielectrophoretic motions of a pair of particles under a uniform electric field(Korean Society of Mechanical Engineers, 2016) Kang, S.; Mannoor, M.; Maniyeri, R.This paper presents two-dimensional direct numerical simulations to explore the effect of the Reynolds number on the Dielectrophoretic (DEP) motion of a pair of freely suspended particles in an unbounded viscous fluid under an external uniform electric field. Accordingly, the electric potential is obtained by solving the Maxwell’s equation with a great sudden change in the electric conductivity at the particle-fluid interface and then the Maxwell stress tensor is integrated to determine the DEP force exerted on each particle. The fluid flow and particle movement, on the other hand, are predicted by solving the continuity and Navier-Stokes equations together with the kinetic equations. Numerical simulations are carried out using a finite volume approach, composed of a sharp interface method for the electric potential and a direct-forcing immersed-boundary method for the fluid flow. Through the simulations, it is found that both particles with the same sign of the conductivity revolve and eventually align themselves in a line with the electric field. With different signs, to the contrary, they revolve in the reverse way and eventually become lined up at a right angle with the electric field. The DEP motion also depends significantly on the Reynolds number defined based on the external electric field for all the combinations of the conductivity signs. When the Reynolds number is approximately below Recr ? 0.1, the DEP motion becomes independent of the Reynolds number and thus can be exactly predicted by the no-inertia solver that neglects all the inertial and convective effects. With increasing Reynolds number above the critical number, on the other hand, the particles trace larger trajectories and thus take longer time during their revolution to the eventual in-line alignment. © 2016, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.Item Intelligent adaptive observer-based optimal control of overhead transmission line de-icing robot manipulator(Robotics Society of Japan ar@rsj.or.jp, 2016) Vijay, M.; Jena, D.[No abstract available]Item Electric Field Reduction in an EHV Substation for Occupational Exposure via Transposition of Conductors(Institute of Electrical and Electronics Engineers Inc., 2018) Devarajan, D.; Punekar, G.S.An attempt is made to reduce the maximum value of rms electric field (E-field) via the transposition of conductors in a 765-kV substation with reference to the occupational exposure. The method is applied to a extra-high-voltage substation, which is under construction. The effect of transposing the bay conductors (alone) and the bus conductors (alone) on the E-field distribution (at 2 m above the ground) over the area of the substation is discussed. Also, the topology of substation conductors that results in the minimum value for the maximum of rms E-fields is obtained via simultaneous transpositions of the bus and bay conductors. The area of the substation where the rms E-field exceeds the reference value of 10 kV/m (International Commission on Non-Ionizing Radiation Protection occupational exposure limit) is also reported for the existing topology. For this topology, the computed maximum value of the rms E-field over the area of the substation is 13.06 kV/m. This E-field is reduced to 7.999 kV/m with the best configuration of substation conductors obtained via transposition. The charge-simulation-method-based generalized algorithm for obtaining the best topology (among all permutations) of substation conductors, which results in the minimum value for the maximum of rms E-field magnitudes over the substation area is also reported. © 1986-2012 IEEE.Item Dispersion-Engineered Transmission Line Loaded Slot Antenna for UWB Applications(Institute of Electrical and Electronics Engineers Inc., 2019) Paul, P.M.; Kandasamy, K.; Sharawi, M.S.; Majumder, B.A transmission line (TL) loaded, compact, ultrawideband (UWB) square slot antenna is proposed in this letter. The square slot is a microstrip line fed and loaded with an array of periodically perturbed TLs to achieve a UWB response from 2.1 to 11.5 GHz. The slot is designed to resonate at 2.6 GHz. The TLs are dispersion engineered to resonate at several frequencies so as to provide a wideband response. Loading of the engineered TLs on the square slot produced multiple resonances without affecting the fundamental mode of the slot antenna. The proposed antenna design is analyzed using dispersion relations and equivalent circuits. The proposed antenna is fabricated on an RT/Duroid 5880 substrate with a size of 50 × 50 × 1.52 mm3. The antenna performance metrics, such as impedance bandwidth, gain, and efficiency, are experimentally verified. Good agreement is obtained between simulated and measured results. © 2018 IEEE.Item Design and simulation of quadrilateral relays in ac transmission lines with vsc-based hvdc systems under phase-to-ground fault condition(Politechnica University of Bucharest Splaiul Independentei 313 - Sector 6 Bucharest 77206, 2019) Muniappan, M.; Vittal, K.P.Voltage source converters (VSC)-based high voltage direct current (HVDC) transmission system can be used to integrate the offshore wind power generation with an AC grid. Due to the interconnection of VSC-HVDC system with the AC grid, an operation of distance relays might get affected. Also, fault resistance plays a significant role in the performance of ground relays. The ground faults have higher fault resistance causes the accuracy of the ground relay gets affected significantly. In this paper, the three-zone quadrilateral characteristic-based distance relay is designed to protect the AC transmission lines under phase-to-ground fault with fault resistance. Simulation studies are carried out to test the performance of the quadrilateral relay under phase-to-ground fault including various fault resistance cases in an AC transmission line with the effect of VSC-HVDC system. The impact of the dynamic conditions of the VSC-HVDC system on the performance of the quadrilateral relays under phase-to-ground fault with fault resistance cases is presented. Also, the performance comparison of the quadrilateral relay with the mho relay under such conditions is presented. © 2019, Politechnica University of Bucharest. All rights reserved.Item Performance Evaluation of Distance Relay in the Presence of Voltage Source Converters-Based HVDC Systems(Korean Institute of Electrical Engineers elecjour@kiee.or.kr, 2019) Muniappan, M.; Vittal, K.P.Voltage source converters (VSC)-based high voltage direct current (HVDC) link is an economical option for the long distance bulk power transmission, and it can be used to interconnect the offshore wind farms with an AC grid. Due to the penetration of VSC-HVDC system into the AC grid, the performance of the distance relay gets affected when a transmission line close to the point of common coupling (PCC) subjected to power system disturbances. In such condition, the PCC voltage is increased due to the VSC-HVDC control action, that causes the Zone-2 fault can be seen as a Zone-3 fault. As a result, the miscoordination of Zone-2 protection can occur in the distance relays. This paper presents both the analytical and simulation studies carried out on a VSC-HVDC system influence on the distance relay performance under fault conditions using PSCAD/EMTDC. Simulation results show that the presence of VSC-HVDC system greatly affects the performance of the Zone-2 and Zone-3 relay in an AC transmission line. Besides, the maloperation of the Zone-2 and Zone-3 relay is mitigated by varying the AC voltage reference input of the decoupled d-q controller of VSC-HVDC. Also, the effect of fault resistance on Zone-1 ground relay performance is analyzed. © 2019, The Korean Institute of Electrical Engineers.Item Mitigation of mutual coupling in 2 X 2 dual slant polarized MIMO antennas using periodic array of SRRs loaded with transmission line for LTE band 40(John Wiley and Sons Inc, 2020) Bellary, A.; Kandasamy, K.; Rao, P.H.2 X 2 dual slant polarized multiple input multiple output (MIMO) antennas with reduced mutual coupling is presented for polarization and spatial diversity. The design of printed periodic array of split ring resonators (SRRs) loaded with horizontal strip transmission line is proposed to mitigate the mutual coupling among the MIMO antenna elements. An equivalent circuit model, characterizes the effect of coupling between the array of SRRs and the loaded transmission line, which together reduces the near field coupling between the adjacent antenna elements. The additional horizontal strip at the bottom is utilized to seek the return current path to the ground plane. Polarization and spatial diversity is achieved by utilizing dual slant 450 polarized antenna elements with eight independent channels. All four dual polarized antenna elements are designed to operate with a VSWR of <2 for (2.3-2.4 GHz) Band 40. Dual slant 450 polarization is achieved by utilizing two printed planar bow-tie antennas in orthogonal orientation. Measured and simulated results shows by incorporating periodic array of SRRs loaded with transmission line a considerable mutual coupling reduction of 25 to 50 dB is achieved in E-plane, H-plane, and D-plane over the required band 40. An isolation of 30 dB and an average gain of 7.5 dB is measured for dual slant 450 polarized antenna elements. MIMO performance metrics in terms of envelope correlation coefficient and diversity gain are also investigated. © 2020 Wiley Periodicals LLCItem Pair trajectories of uncharged conducting spheres in an electric field(American Institute of Physics Inc., 2023) Thiruvenkadam, N.; Patra, P.; Vishwanath, V.K.; Roy, A.In this paper, we study the role of electrostatic forces on pair trajectories of two uncharged conducting spheres subject to an external electric field. We consider the hydrodynamic interactions between the spheres as they move relative to one another. Previous studies have shown that electric-field-induced forces on a two-sphere system are always attractive, except for the configuration when the line joining the centers is perpendicular to the external electric field. In the current study, we derive the asymptotic form of the interparticle force induced by the electric field in the lubrication limit for arbitrary size ratios. The attractive electric force diverges as the separation approaches zero. Thus, our calculation shows that the electric-field-induced forces can overcome the continuum lubrication resistance and allow finite time contact between the surfaces of two spherical conductors. We calculate the asymptotic variation of interparticle separation using the near-field asymptotic expressions for the electric-field-induced forces, exploring the role of hydrodynamic interactions in interparticle motion parallel and perpendicular to the electric field. © 2023 Author(s).Item Comparative Analysis of 500 kV Double-Circuit Transmission Line Electric Field Intensity: Ethiopian Lines Compliance With ICNIRP(Institute of Electrical and Electronics Engineers Inc., 2024) Tefera, T.N.; Punekar, G.S.; Ibrahim Yassin, K.; Tuka, M.The high-intensity electric fields, which are in the vicinity of power transmission lines, have adverse effects on human and other living beings if they are not within the specified limits. The International Commission on Non-ionizing Radiation Protection (INCIRP) specifies guidelines for these E-fields from the perspective of public exposure at the ground level and sets it to 5 kV/m at 50 Hz. Thus, this study was aimed at analyzing and comparing the E-fields intensity of differently configured double-circuit 500 kV transmission lines at a height of 1 m above the ground plane. Charge Simulation Method (CSM) using MATLAB as a programming platform is used for this study. Among the tower configurations studied, a configuration that provided minimum E-fields with minimum ground clearance was identified. From the actual built transmission lines included in the study, vertical lines configuration produces a minimum E-fields intensity of 4.565 kV/m root mean square and fulfills the INCIRP requirement. However, triangular line configuration is the preferable configuration for 500 kV double circuit transmission lines giving the least E-fields at the ground with minimum ground clearance using optimized phase sequence arrangements irrespective of other comparative parameters. Additionally, an evaluation of these line configurations based on the distribution of the conductor surface E-fields was conducted. The study reveals that the E-fields on the surface of the transmission line conductors included in the study remains significantly below the intrinsic breakdown strength of atmospheric air. Therefore, it was anticipated that the designs will remain free from corona discharge under fair weather conditions. © 2013 IEEE.