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A Novel AE Based Algorithm for PD Localization in Power Transformers
Mehdizadeh, Sina,Yazdchi, Mohammadreza,Niroomand, Mehdi The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.6
In this paper, a novel algorithm for PD localization in power transformers based on wavelet de-noising technique and energy criterion is proposed. Partial discharge is one of the main failures in power transformers. The localization of which could be very useful for maintenance systems. Acoustic signals due to a PD event are transient, irregular and non-repetitive. So wavelet transform is an efficient tool for this signal processing problem that gives a time-frequency demonstration. First, different wavelet based de-noising methods are analyzed. Then, a reasonable structure for threshold value determining and applying manner on signals is presented. Evaluated errors are good evidences for choices. Next, applying the elimination low energy frequency bands is discussed and developed as a de-noising method. Time differences between signals are used for PD localization. Different ways in time arrival detection are introduced and a novel approach in energy criterion method is presented. At the end, the quality of algorithm is verified through the different assays in lab.
A Novel AE Based Algorithm for PD Localization in Power Transformers
Sina Mehdizadeh,Mohammadreza Yazdchi,Mehdi Niroomand 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.6
In this paper, a novel algorithm for PD localization in power transformers based on wavelet de-noising technique and energy criterion is proposed. Partial discharge is one of the main failures in power transformers. The localization of which could be very useful for maintenance systems. Acoustic signals due to a PD event are transient, irregular and non-repetitive. So wavelet transform is an efficient tool for this signal processing problem that gives a time-frequency demonstration. First, different wavelet based de-noising methods are analyzed. Then, a reasonable structure for threshold value determining and applying manner on signals is presented. Evaluated errors are good evidences for choices. Next, applying the elimination low energy frequency bands is discussed and developed as a de-noising method. Time differences between signals are used for PD localization. Different ways in time arrival detection are introduced and a novel approach in energy criterion method is presented. At the end, the quality of algorithm is verified through the different assays in lab.
Arash Shams,Mohammadreza Mehdizadeh,HamidReza Teimoury,Mehrsa Emami,Seyed Amin Mirmohammadi,Samahe Sadjadi,Eduard Bardají,Albert Poater,Naeimeh Bahri-Laleh 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.116 No.-
The role of the pore architecture of the Ziegler-Natta (ZN) catalysts in the propylene polymerizations isunveiled, towards the catalyst activity, H2– and comonomer-response, and final properties of the synthesizedpolymer. In this regard, two commercially available ZN catalysts (Cat-A and Cat-B belong to the 4thgeneration, containing diisobutyl phthalate as internal donor) with a similar composition but with differentpore structures were employed in propylene/1-hexene copolymerizations in the presence of H2 as achain transfer agent. Although pore diameter does not alter H2-response noticeably, it significantly affectsthe comonomer incorporation as well as the distribution of the isotactic sequence length in the copolymerbackbone. Cat-A with a lower surface area, a larger pore diameter, and a wider inlet showed slightlyhigher activities in homopolymerization and copolymerization experiments. According to the selfnucleationand annealing (SSA) results, the copolymer produced from Cat-A demonstrated lower isotacticsequence length and lamellar thickness contents owing to its larger pore diameter with wider inlets. Moreover, Temperature Rising Elution Fractionation (TREF) profiles asserted SSA data in which thecopolymer from Cat-A represented a higher content of low elution temperatures fractions, due to itshigher comonomer content. These findings will lead to catalysts for different polypropylene grades.