Scheme for Reducing Harmonics in Output Voltage of Modular Multilevel Converters with Offset Voltage Injection

Devnath Anupom,Dong-Cheol Shin,이동명 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

This paper proposes a new THD reduction algorithm for modular multilevel converters (MMCs) with offset voltage injection operated in nearest level modulation (NLM). High voltage direct current (HVDC) is actively introduced to the grid connection of offshore wind powers, and this paper deals with a voltage generation technique with an MMC for wind power generation. In the proposed method, third harmonic voltage is added for reducing the THD. The third harmonic voltage is adjusted so that each of the pole voltage magnitudes maintains a constant value with a maximum number of (N+1) levels, where N is the number of sub-modules per arm. By using the proposed method, the THD of the output voltage is mitigated without increasing the switching frequency. In addition, the proposed method has advantageous characteristics such as simple implementation. As a part of this study, this paper compares the THD results of the conventional method and the proposed method with offset voltage injection to reduce the THD. In this paper, simulations have been carried out to verify the effectiveness of the proposed scheme, and the proposed method is implemented by a HILS (Hardware in the Loop Simulation) system. The obtained results show agreement with the simulation results. It is confirmed that the new scheme achieved the maximum level output voltage and improved the THD quality.

Static deflection of nonlocal Euler Bernoulli and Timoshenko beams by Castigliano's theorem

Devnath, Indronil,Islam, Mohammad Nazmul,Siddique, Minhaj Uddin Mahmood,Tounsi, Abdelouahed Techno-Press 2022 Advances in nano research Vol.12 No.2

This paper presents sets of explicit analytical equations that compute the static displacements of nanobeams by adopting the nonlocal elasticity theory of Eringen within the framework of Euler Bernoulli and Timoshenko beam theories. Castigliano's theorem is applied to an equivalent Virtual Local Beam (VLB) made up of linear elastic material to compute the displacements. The first derivative of the complementary energy of the VLB with respect to a virtual point load provides displacements. The displacements of the VLB are assumed equal to those of the nonlocal beam if nonlocal effects are superposed as additional stress resultants on the VLB. The illustrative equations of displacements are relevant to a few types of loadings combined with a few common boundary conditions. Several equations of displacements, thus derived, matched precisely in similar cases with the equations obtained by other analytical methods found in the literature. Furthermore, magnitudes of maximum displacements are also in excellent agreement with those computed by other numerical methods. These validated the superposition of nonlocal effects on the VLB and the accuracy of the derived equations.

Scheme for Reducing Harmonics in Output Voltage of Modular Multilevel Converters with Offset Voltage Injection

Anupom, Devnath,Shin, Dong-Cheol,Lee, Dong-Myung The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.6

This paper proposes a new THD reduction algorithm for modular multilevel converters (MMCs) with offset voltage injection operated in nearest level modulation (NLM). High voltage direct current (HVDC) is actively introduced to the grid connection of offshore wind powers, and this paper deals with a voltage generation technique with an MMC for wind power generation. In the proposed method, third harmonic voltage is added for reducing the THD. The third harmonic voltage is adjusted so that each of the pole voltage magnitudes maintains a constant value with a maximum number of (N+1) levels, where N is the number of sub-modules per arm. By using the proposed method, the THD of the output voltage is mitigated without increasing the switching frequency. In addition, the proposed method has advantageous characteristics such as simple implementation. As a part of this study, this paper compares the THD results of the conventional method and the proposed method with offset voltage injection to reduce the THD. In this paper, simulations have been carried out to verify the effectiveness of the proposed scheme, and the proposed method is implemented by a HILS (Hardware in the Loop Simulation) system. The obtained results show agreement with the simulation results. It is confirmed that the new scheme achieved the maximum level output voltage and improved the THD quality.

Relationships between Fecundity and Total Length, Body Weight, Ovary Length, and Ovary Weight of Hilsa Shad, Tenualosa ilisha Hamilton, in Patuakhali, Bangladesh

Borun K. Mondal,Sukumar Devnath,Dinesh C. Shaha,Mohammed N.A.khan,최재석 한국수산과학회 2008 Fisheries and Aquatic Sciences Vol.11 No.2

Relationships between total length (TL) and fecundity, body weight and fecundity, ovary length and fecundity, and ovary weight and fecundity of hilsa shad, Tenualosa ilisha Hamilton, collected from Kuakata, Patuakhali, Bangladesh, were studied. During the sampling period, the fecundity of hilsa was found to range from 169,000 (fish TL=28.0 cm, weight=250 g) to 1,088,000 (fish TL=40.5 cm, weight=955 g) with a mean of 520±53×1,000. The number of eggs per gram of ovary for samples collected from the anterior, middle, and posterior regions of the ovary were also recorded, but no significant variation was found among ovary regions at the 5% level of significance. Fecundity increased with fish TL and weight. The regression equations obtained in arithmetic forms of relationships between TL and fecundity (F), body weight (BW) and fecundity, ovary length (OL) and fecundity, and ovary weight (OW) and fecundity were F=-887,896+ 40,511×TL (r=0.85), F=67,577+755.44×BW (r=0.85), F=-562,070+87,668×OL (r=0.75) and F=124,815+6,596.7×OW (r=0.84), respectively. The relationships between fecundity and TL, body weight, ovary length, and ovary weight were linear, and the ‘r’ values were highly significant (p<0.01). These results provide valuable data for the restoration of hilsa resources, which are economically important but have shown reduced productivity in nations adjacent to the Bay of Bengal.

Relationships between Fecundity and Total Length, Body Weight, Ovary Length, and Ovary Weight of Hilsa Shad, Tenualosa ilisha Hamilton, in Patuakhali, Bangladesh

Mondal, Borun Kumar,Devnath, Sukumar,Shaha, Dinesh Chandra,Khan, Mohammed Nurul Absar,Choi, Jae-Suk The Korean Society of Fisheries and Aquatic Scienc 2008 Fisheries and Aquatic Sciences Vol.11 No.2

Relationships between total length (TL) and fecundity, body weight and fecundity, ovary length and fecundity, and ovary weight and fecundity of hilsa shad, Tenualosa ilisha Hamilton, collected from Kuakata, Patuakhali, Bangladesh, were studied. During the sampling period, the fecundity of hilsa was found to range from 169,000 (fish TL=28.0cm, weight=250g) to 1,088,000 (fish TL=40.5cm, weight=955g) with a mean of $520{\pm}53{\times}1,000$. The number of eggs per gram of ovary for samples collected from the anterior, middle, and posterior regions of the ovary were also recorded, but no significant variation was found among ovary regions at the 5% level of significance. Fecundity increased with fish TL and weight. The regression equations obtained in arithmetic forms of relationships between TL and fecundity (F), body weight (BW) and fecundity, ovary length (OL) and fecundity, and ovary weight (OW) and fecundity were $F=-887,896+40,511{\times}TL(r=0.85)$, $F=67,577+755.44{\times}BW(r=0.85)$, $F=-562,070+87,668{\times}OL(r=0.75)$ and $F=124,815+6,596.7{\times}OW (r=0.84)$, respectively. The relationships between fecundity and TL, body weight, ovary length, and ovary weight were linear, and the 'r' values were highly significant (p<0.01). These results provide valuable data for the restoration of hilsa resources, which are economically important but have shown reduced productivity in nations adjacent to the Bay of Bengal.

In silico profiling of analgesic, antidiarrheal and antihyperglycemic properties of Tetrastigma bracteolatum (Wall.) leaves extract supported by in vivo studies

Md. Naharul Islam,Hiron Saraj Devnath,Maisha Maliha Medha,Ritu Porna Biswas,Nripendra Nath Biswas,Biswajit Biswas,Samir Kumar Sadhu 경희대학교 융합한의과학연구소 2023 Oriental Pharmacy and Experimental Medicine Vol.23 No.3

Hill tract plant Tetrastigma bracteolatum (Wall.) (Family-Vitaceae) is traditionally used for headache, indigestion and stomach disorder by the tribal people in Bangladesh. In this study, the ethanolic leaves extract of TB was investigated for screening its phytochemical constituents and assessing the antioxidant, analgesic, antidiarrheal and antihyperglycemic potential. In DPPH free radical scavenging assay, the extract showed good radical scavenging potential with SC50 (concentration for 50% scavenging) value of 56 µg/ml. Analgesic activity test was performed by acetic acid-induced writhing method, where the extract inhibited writhing by 28.8% and 51.5% at the doses of 250 and 500 mg/kg bw, respectively. The extract inhibited defecation by 36.2% and 60.3% at the doses of 250 and 500 mg/kg bw in castor oil-induced diarrheal mice. In the evaluation of antihyperglycemic activity by oral glucose tolerance test (OGTT), the extract reduced blood glucose levels in a dose-dependent manner after 90 min, compared to the control group. The extract was also assessed for its in vitro α-glucosidase inhibition capacity but no demonstrable efect was observed. Fourteen chemical compounds were identifed through GC–MS analysis of the extract with the highest amount of 1,2,3,4,4a,5,8,9,12,12a-decahydro-1,4-methanobenzocyclodecene (5.46%). Few compounds displayed better binding afnity with the active site of NADPH oxidase, nitric oxide synthase, M3 muscarinic acetylcholine receptor and sulfonylurea receptor than standard drugs in molecular docking studies. Therefore, the extract of TB may be used as a potential source of drug leads for various ailments.