Faculty Publications
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Item Finite element method magnetics based demonstration of rotating field in 4-pole induction motor(2013) Punekar, G.S.; Devarajan, D.; Tantry, G.H.The explanation related to the concept of Rotating Magnetic Field (RMF) in 3-phase induction motor (IM) and its visualization is a tricky issue in teaching-learning process. The complexity increases with the number of poles. Hence visualization of RMF for a 4-pole Induction motor is attempted via magnetic field distribution pattern(s). The aim of this paper is to explore and utilize the capability of Finite Element Method Magnetics (FEMM) as a tool for demonstrating rotating magnetic field effect produced in the stator of a 3-phase induction motor. In addition to the RMF demo, visual correlation between angular rotations of electrical wave with mechanical degree is reported. Also, the effect of phase sequence reversal is incorporated in the graphical exhibition. © 2013 Springer.Item A comparative study of field computation methods: Charge simulation method and method of moments(Institute of Electrical and Electronics Engineers Inc., 2018) Devarajan, D.; Punekar, G.S.Numerical methods plays a vital role in computation of electric fields for the design of high voltage systems. For electric fields studies related to high voltage applications, the preferred numerical methods are charge simulation method (CSM) and method of moments (MoM). In the present study, the performance of these two numerical methods are analyzed by simulating sphere-plane gap arrangement (which has an analytical solution to compare). Through this example, CSM is found to be more accurate compared to MoM. Further, the effect of change in sphere-plane gap geometry on the electric field computed is reported and discussed. © 2018 IEEE.Item Electric stress on the surface of conductors in an Extra High Voltage substation(Institute of Electrical and Electronics Engineers Inc., 2018) Devarajan, D.; Punekar, G.S.; Kishore, N.K.In high voltage equipment and substations, the electric field distribution on the surface of the conductor is important from the point of designing the insulation systems. In outdoor substation, the atmospheric air acts as an insulation medium and the electric-fields (e-fields) on the surface of the conductors should not exceed the breakdown strength of air (2122 kV/m rms). Based on the analysis of surface e-fields of substation conductors, one can adjudge whether any redesign in terms of conductor effective radius and clearances are required. One such analysis of surface e-fields in a 765 kV substation in central India is carried out. Charge Simulation Method (CSM) is used as a numerical technique. The surface e-field plot on the substation conductors are reported. The highest e-fields are on the surface of transmission line conductors with 1504 kV/m. Thus, the design should work corona free. © 2018 IEEE.Item Spatiotemporal electric field distribution in an EHV substation in view of occupational exposure(Institute of Electrical and Electronics Engineers Inc., 2019) Devarajan, D.; Punekar, G.S.; Kishore, N.K.With the increase in the transmission voltage levels, the effect of non-ionizing radiation (NIR) becomes a major concern. The International Commission on Non-Ionizing Radiation (ICNIRP) provides the guidelines for protection against NIR. It suggests the reference electric field (e-field) value of 10 kV/m for occupational exposure and 5 kV/m for general public exposure for the substation. In view of this, e-field prevailing in a 765 kV generating substation is studied in the present work to assess the spatiotemporal distribution using charge simulation method (CSM) based model. This should give a feel of the possible threat posed by these fields to the working personal due to NIR. The upcoming EHV substation in central India is considered with its bays, transmission lines, buses, and ground wires. The instantaneous values of e-field are computed at different instances over the 50 Hz voltage cycle, at 2 m height above the ground plane over the entire substation arena. The demo of spatiotemporal variation of e-field computed at different instants of time over a cycle using simulating charges taken from the real-number-field will be presented and discussed during the presentation. This would result in a time-space changing e-field-force, and give a feel of creation of churning of air and electric wind. This will have much higher significance at the heights were conductors are placed where the e-fields are higher. It is also shown that because of spatiotemporal variation of e-field, the rms value of e-field can be easily obtained using simulating charges taken from complex-number-field which is of significance from the point of view of ICNIRP guidelines. © 2019 IEEE.Item E-field computation in 765 kV substation using CSM with reference to occupational exposure(Institution of Engineering and Technology journals@theiet.org, 2018) Devarajan, D.; Punekar, G.S.; Bhatt, N.S.With the increase in transmission voltage level, and the guidelines of the International Commission on Non-Ionising Radiation Protection (ICNIRP), the effects of non-ionising radiation on biological elements at high-voltage substations have gained significant importance. The electric field (E-field) distribution in an upcoming 765 kV substation in the Indian subcontinent is computed using the charge simulation method (CSM). CSM is used to model the 765 kV bays, transmission lines, buses, and ground wires in the substation. The three-dimensional (3D) E-field is calculated through the superimposition of E-fields obtained in two orthogonal planes using infinite-line charges. This proposed method of using infinite-line charges gives realistic results. The simplistic model using infinite-line charges greatly reduces the complexity of the CSM-based model (due to the reduced number of charges) apart from increasing the CSM-based model accuracies. This fact has been demonstrated by comparing these results with those of CSM-3D-model of a detailed bay model (including major equipment and associated support structures). The complex-charge-based CSM helps in computing the root mean square value of the E-field at a point, directly, as per ICNIRP guidelines. This RMS value of the E-field is compared with the occupational exposure reference value prescribed in the ICNIRP guidelines. © The Institution of Engineering and Technology 2017.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 GA-CSM based optimized clearances for the reduction of occupational exposure in EHV substation☆(Elsevier Ltd, 2023) Devarajan, D.; Punekar, G.S.The magnitude of the electric field (E-field) in a 765 kV substation is reduced by altering the conductor clearances in view of the occupational exposure limits. Multi-objective genetic algorithm (GA) along with the charge simulation method (CSM) is utilized in arriving at the optimal clearances of the substation conductors. An EHV substation is modeled with the dimensions and the clearances as in the actual layout of a substation. The E-field results obtained using the finite-line based modeling and infinite-line based modeling of conductors, are compared in terms of the model accuracy and the computational time. The advantages of using the infinite-line based CSM model in view of the occupational exposure is detailed. With the proposed GA-CSM routine, the maximum value of the E-field in the substation is reduced to 10 kV/m (from the existing value of 13 kV/m). The proposed method is used with the existing topology and the best possible transposed topology to obtain the modified layouts. A novel EHV substation layout with different ground clearances for the inner bays and the outer bays is presented. The GA-CSM routine proposed in this work is applicable to any EHV substation with the multiple conductor arrangements. © 2022