Finite-time Secondary Frequency Modulation of Microgrid Based on Event Triggering Mechanism

Chenglong Zhou,Ze Li,Guozeng Cui,Yifan Chen,Wangjun Hao 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.4

This paper designs a ratio consistency algorithm based on event triggering mechanism aiming at the frequency recovery deviation caused by traditional droop control in microgrid. It achieves secondary frequency modulation in microgrid by adjusting the active power setting value. The max-min consistency algorithm is proposed to realize asymptotic consistency of distributed power supply in a finite time. Communication delay is added to ensure the accuracy of frequency update and verifies the robustness of the algorithm against itself. Meanwhile, the validity of event triggering conditions is verified. Finally, the simulation examples are carried out to prove the correctness and superiority of the proposed finite-time control strategy.

Detrital-zircon geochronology and Hf isotope of Paleozoic sedimentary rocks in the Jilin Province, NE China: tectonic significance for microcontinental blocks of eastern Central Asian Orogenic Belt

Chenglong Shi,Xiaozhong Ding,Yanxue Liu,Xiaodong Zhou 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.5

We undertook U-Pb-Hf isotope testing of detrital zircons from Late Paleozoic sedimentary rocks in the Jilin Province, NE China, with the aim of constraining the tectonic evolution of eastern Central Asian Orogenic Belt. The age populations of the detrital zircons from the sandstone of the Jiefangcun Formation in the Songliao Block are ~2234, ~1782, ~1030–921, ~817, ~540, and ~381–254 Ma, whereas those of the zircons from the greywacke of the Permian Kedao Formation in the Songliao Block yield are ~2436, ~1905, ~1692, 1146–1170, ~554–498, and ~342–255 Ma. Combined Hf isotope characteristics, these ages reveal that: (1) rocks from the Jiefangcun and Kedao formations were deposited after 254 and 255 Ma, respectively; (2) these formations were sourced mainly from the Songliao Block and the Jiamus Terrane in the eastern CAOB and to a lesser amount, from the northern margin of the NCC; and (3) it appears that several remnants of ancient Precambrian basement occur adjacent to these Late Paleozoic strata that occur within the microcontinental blocks. Detrital zircons from the silty sandstone of the Miaoling Formation in the western margin of the Khanka Terrane yield peak age populations of 508–476, 463–396, and 348–258 Ma, having similar εHf(t) values to those obtained from zircons within the Jiamusi Terrane. These data indicate that (1) deposition of the Miaoling Formation in the western margin of the Khanka Terrane had started by 258 Ma, and (2) these sediments were sourced mainly from the Jiamusi Terrane and local magmatic rocks. The widespread occurrence of detrital zircons with ages of 480–550 Ma and positive εHf(t) values within the Late Paleozoic strata in the Songliao Block and the Jiamusi–Khanka Terrane, indicates that the amalgamation of these blocks took place during the middle stage of the Paleozoic, probably after the Silurian, prior to the Late Permian.

An adaptive deviation-resistant neutron spectrum unfolding method based on transfer learning

Cao, Chenglong,Gan, Quan,Song, Jing,Yang, Qi,Hu, Liqin,Wang, Fang,Zhou, Tao Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.11

Neutron spectrum is essential to the safe operation of reactors. Traditional online neutron spectrum measurement methods still have room to improve accuracy for the application cases of wide energy range. From the application of artificial neural network (ANN) algorithm in spectrum unfolding, its accuracy is difficult to be improved for lacking of enough effective training data. In this paper, an adaptive deviation-resistant neutron spectrum unfolding method based on transfer learning was developed. The model of ANN was trained with thousands of neutron spectra generated with Monte Carlo transport calculation to construct a coarse-grained unfolded spectrum. In order to improve the accuracy of the unfolded spectrum, results of the previous ANN model combined with some specific eigenvalues of the current system were put into the dataset for training the deeper ANN model, and fine-grained unfolded spectrum could be achieved through the deeper ANN model. The method could realize accurate spectrum unfolding while maintaining universality, combined with detectors covering wide energy range, it could improve the accuracy of spectrum measurement methods for wide energy range. This method was verified with a fast neutron reactor BN-600. The mean square error (MSE), average relative deviation (ARD) and spectrum quality (Qs) were selected to evaluate the final results and they all demonstrated that the developed method was much more precise than traditional spectrum unfolding methods.

Evaluation of the horizontal electric field of the lightning channel with the fast convergent sommerfeld integral tail

Zou, Jun,Zhou, Chenglong,Li, Wenwen,Lee, Jae-bok,Chang, Sughun Emerald Group Publishing Limited 2013 Compel Vol.32 No.6

<B>Purpose</B> - The electromagnetic field radiated from a lightning channel is the excitation for analyzing the field-to-transmission line coupling problem. The purpose of this paper is to propose a novel efficient approach to evaluate the horizontal electric field of the lightning channel expressed by the generalized Sommerfeld integral. <B>Design/methodology/approach</B> - The asymptotic integral is extracted from the original one, which actually makes the Sommerfeld integral tail reach its convergence very quickly. To handle the sharp variance around k0, a closed-form integral, which is obtained by replacing the original kernel with an approximated function, is presented in detail. The numerical examples validated the proposed approach in the both frequency and time domain. <B>Findings</B> - The approach proposed in this paper has been validated by the comparison with results in other papers. The agreement among these results reaches very well, and the approach proposed in this paper is more efficient and easy to implement, especially for the calculation of the tail integral part. <B>Originality/value</B> - In accordance with the numerical experiments, the proposed approach can be served as a qualified candidate in terms of computational efficiency to evaluate the electromagnetic field generated by the lightning channel.

The “living” Feature of the ATRP Macroinitiators in Different Catalytic Systems

Yazhen Wang,Li Liu,Shaobo Dong,Xilai Zhou,Chenglong Wang,Zhen Shi 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.2

Atom transfer radical polymerization (ATRP) has achieved widespread use in living polymerization. However, until now there hasbeen little report that macroinitiators initiate polymerization in different catalytic systems. The preparation of bromine-terminatedpolymethyl methacrylate (PMMA-Br) and chlorine-terminated PMMA (PMMA-Cl) were carried out via reverse atom transferradical polymerization (RATRP). The PMMA with halogen termination and narrow polydispersity (Mn = 12,000–15,000 g/mol,Mw/Mn = 1.1–1.2) were used as macroinitiators. The block copolymer of polymethyl methacrylate and polyacrylonitrile (PMMAb-PAN) was prepared in different catalytic systems through normal ATRP. The analyses of the 1H NMR showed that the PMMAprepared by RATRP were end-functionalized by halogen atoms, demonstrated the activities of the PMMA macroinitiators. Themolecular weight and polydispersity index (PDI) of the polymers were analyzed using gel permeation chromatography (GPC). The results indicated that the block polymers that the molecular weight of the block copolymer after chain extension has increasedsignificantly and the molecular weight distribution is narrow (Mn = 17,000–25,000 g/mol, Mw/Mn = 1.1–1.3). The kinetics ofthese polymerization processes were studied as a function of monomers to the macroinitiator molar ratio. It was found that thepolymerizations in different catalytic systems coincidence first-order kinetics with respect to monomers.

Application of self-centering wall panel with replaceable energy dissipation devices in steel frames

Sisi Chao,Hanheng Wu,Tianhua Zhou,Tao Guo,Chenglong Wang 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.32 No.2

The self-centering capacity and energy dissipation performance have been recognized critically for increasing the seismic performance of structures. This paper presents an innovative steel moment frame with self-centering steel reinforced concrete (SRC) wall panel incorporating replaceable energy dissipation devices (SF-SCWD). The self-centering mechanism and energy dissipation mechanism of the structure were validated by cyclic tests. The earthquake resilience of wall panel has the ability to limit structural damage and residual drift, while the energy dissipation devices located at wall toes are used to dissipate energy and reduce the seismic response. The oriented post-tensioned strands provide additional overturning force resistance and help to reduce residual drift. The main parameters were studied by numerical analysis to understand the complex structural behavior of this new system, such as initial stress of post-tensioning strands, yield strength of damper plates and height-width ratio of the wall panel. The static push-over analysis was conducted to investigate the failure process of the SF-SCWD. Moreover, nonlinear time history analysis of the 6-story frame was carried out, which confirmed the availability of the proposed structures in permanent drift mitigation.

Thermal-hydraulic research on rod bundle in the LBE fast reactor with grid spacer

Liu Jie,Song Ping,Zhang Dalin,Wang Shibao,Lin Chao,Liu Yapeng,Zhou Lei,Wang Chenglong,Tian Wenxi,Qiu Suizheng,Su G.H. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.7

The research on the flow and heat transfer characteristics of lead bismuth(LBE) is significant for the thermal-hydraulic calculation, safety analysis and practical application of lead-based fast reactors(LFR). In this paper, a new CFD model is proposed to solve the thermal-hydraulic analysis of LBE. The model includes two parts: turbulent model and turbulent Prandtl, which are the important factors for LBE. In order to find the best model, the experiment data and design of 19-pin hexagonal rod bundle with spacer grid, undertaken at the Karlsruhe Liquid Metal Laboratory (KALLA) are used for CFD calculation. Furthermore, the turbulent model includes SST k u and k ε; the turbulent Prandtl includes Cheng-Tak and constant (Prt ¼1.5,2.0,2.5,3.0). Among them, the combination between SST k u and Cheng-Tak is more suitable for the experiment. But in the low Pe region, the deviation between the experiment data and CFD result is too much. The reason may be the inlet-effect and when Pe is in a low level, the number of molecular thermal diffusion occupies an absolute advantage, and the buoyancy will enhance. In order to test and verify versatility of the model, the NCCL performed by the Nuclear Thermal-hydraulic Laboratory (Nuthel) of Xi'an Jiao tong University is used for CFD to calculate. This paper provides two verification examples for the new universal model

Changes in distribution and morphology of Tamarix ramosissima nebkhas in an oasis-desert ecotone

Chaofan Li,Fan Yang,Xinqian Zheng,Zhangyong Han,Honglin Pan,Chenglong Zhou,Chunrong Ji 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.5

In the oasis-desert ecotone, nebkhas are of great importance for blocking the intrusion of shifting sand and maintaining the ecological security of oases. The morphological characteristics of nebkhas have been widely researched. However, their spatial distribution and morphological variation with the environment remain unclear. In this paper, we systematically analyzed the spatial distribution pattern, morphological changes, and potential indicative significance of Tamarix ramosissima nebkhas (that is, nebkhas formed around T. ramosissima) in a typical oasis-desert ecotone in Northwest China. Our results showed that the intensity of aeolian activities increased from the inside to the outside of the ecotone, and only T. ramosissima shrubs with high tolerance to aeolian activities could survive. Moreover, from the inside to the outside of the ecotone, the density of the T. ramosissima nebkhas decreased, their size increased, and spatial distribution shifted from aggregation to random. The T. ramosissima shrub can trap aeolian transport and protect nebkhas, leading to sand accumulation in the space between, and leeward edges of, the shrubs. Wind erosion mainly occurs to the windward side and along the sides of the nebkhas. Further, the protective effect of the shrub gradually increased with its growth in a year, resulting in the gradually changed of nebkha surface from wind erosion to sand accumulation, and the nebkha volume showed a fluctuating state of first decreasing and then increasing. This indicates that wind erosion and sand accumulation on the nebkha surface were closely related to the growth cycle of the shrub. In addition, nebkhas exhibited a spatial pattern of growth, inside of the ecotone, to degradation, outside of the ecotone. These results indicate that we should focus on the outside of the ecotone to ensure the ecological stability of oases.

Comparison and Analysis of Meteorological Variables Observed from the Glacier Area over the Tianshan Mountains in Kyrgyzstan and China

Honglin Pan,Wen Huo,Kanike Raghavendra Kumar,Ali Mamtimin,Minzhong Wang,Junjian Liu,Chenglong Zhou,Fan Yang,Xinghua Yang 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.2

Due to the special natural environment over the glacier area in the Tianshan Mountains, the observation of meteorological data became difficult and is strictly scarce. Using the available data observed from the automatic meteorological station (AMS) installed on theWestern Tianshan Mountain Station (WTMS) in Kyrgyzstan, the daily and seasonal variations of meteorological variables including air temperature (AT, °C), air pressure (AP, hPa), relative humidity (RH, %), and wind direction and speed (WD and WS, deg and m/s, respectively), as well as total radiation (TR, W/m2) were primarily analyzed during the period from September 2016 to May 2017. These are compared with the meteorological data obtained from the AMS in the Eastern Tianshan Mountain Station (Daxigou Station, hereafter named as ETMS) in China. Further, the comparison study between the observed data from the WTMS and the NCEP/NCAR reanalysis data was performed to test the feasibility of reanalysis data in the vicinity of the Western Tianshan Mountains. The results revealed are as follows: (1) the observed data between the WTMS and ETMS presented high correlations, and the meteorological parameters detected from the ETMS were certainly representative of the variations in theWTMS. (2) The RH in the two regions showed comparatively high values ranging from 40%to 70%indicate the abundant amount of atmospheric water vapor content near the ground in the Tianshan Mountain area. (3) The predominant WD both in the WTMS and ETMS near the ground was along the south-east direction, with the values of WS between 0 and 2 m/s were accounted the largest proportion in two stations. (4) The NCEP/NCAR reanalysis data can reflect the changes in the synoptic weather scale of AT, RH, and AP to some extent. (5) The NCEP/NCAR reanalysis data of AT and RH were underestimated by 7.2% and 45.2% in the WTMS, respectively. Whereas, the values of AP, WD, and WS were overestimated by 83.8%, 28.8%, and 74.3%, respectively over the WTMS.