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Gundavarapu Venkata Nagesh Kumar,Polamraju V. S. Sobhan,Pakalapati Janaki,Duvvada Deepak Chowdary,Bali Sravana Kumar 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.2
The establishment of supporting insulators plays a vital role in the continuous operation of the three-phase Gas Insulated Busduct (GIB), which primarily depends on the distribution of electric fi eld stress on the spacer surface. Shape control is a technique used along the spacer surface to achieve uniform fi eld intensity, but this technique can also lead to very irregular shapes. The Triple Junction (TJ) is the region where the fi eld stress has to be reduced. Over a period, high fi eld stresses along the spacer surface will result in a surface fl ashover and thus de-energize the complete GIB, leading to enormous losses economically. In this paper, a Functionally Graded Material (FGM) spacer for a three-phase GIB has been designed with more number of gradings and further fi eld stress at TJ is minimized by inserting and reshaping the metal inserts (MI) at the end of the enclosure. By doping them with diff erent permittivity values, functionally graded materials are spatially distributed with multiple fi ller materials to achieve uniform stress on the electric fi eld. Simulation is carried out with the FGM and epoxy (post type) Spacers for diff erent voltages and FGM gradings. With MI, the stress is minimized and an enhanced uniform fi eld allocation along the surface is obtained.
Study of Electric Field Stress with Metallic Particle Adhering to FGM Spacer in Three Phase GIS
Janaki Pakalapati,Karthick Nagaraj,Venkata Nagesh Kumar Gundavarapu 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.5
Recently, spacer design is considered as an important factor for the smooth functioning of three phase gas insulated busduct (GIB) to prevent itself from several defects like delamination, void, particle etc. In this paper, a post type spacer with functionally graded material (FGM) has been designed for a three phase GIB with particle and further electric field stress is minimized by inserting metal inserts. FGM post type spacer is spatially distributed with multiple fillers materials to achieve uniform electric field stress using the finite element method. Simulation is carried out with the designed spacer and with a particle as a defect for different FGM gradings and operating voltages. The effect particle with diff erent sizes is minimized with the insertion of the metal insert to the post type FGM spacer and the results obtained are presented and analyzed.
Ramisetty Uma Maheswari,Chennupati Sumanth Kumar,Gundavarapu Venkata Nagesh Kumar 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.5
Designing the time domain training sequences is very critical in multi carrier transmission which degrades the performance as it is contaminated by diff erent blocks in diff erent cells. To improve the spectral effi ciency and high accuracy, MU-MIMO needs the sensing matrix to be reduced by using the training sequence design and optimization. Integrating the training sequence design and sparse channel estimation improves the capacity of the system. The capacity can be enhanced by reducing the bit error rate. The system capacity for multi user- multi-input and multi output (MU-MIMO) is studied by proper channel estimation with compressed sensing model. The design and optimization of training sequence is analysed for MUMIMO model using auto coherence and block coherence matrices. The block coherence matrix is optimized using cuckoo algorithm for obtaining lower coherence value for diff erent sparsity values. The performance improvement in terms of signal to noise ratio is 1 dB for single user- multi-input and multi output (SU-MIMO) using genetic algorithm and the performance of MU-MIMO is observed to be 0.93 dB using cuckoo algorithm.