Guanghua Zheng^1,2, Chaolin Luo^1,3, Mengen Shen^1,*, Wanzhong Lv⁴, Wenbo Jiang⁴, Weibo Yang²

Energy Engineering, Vol.120, No.4, pp. 985-1000, 2023, DOI:10.32604/ee.2023.024372 - 13 February 2023

Abstract To solve the problems of low precision of weak feature extraction, heavy reliance on labor and low efficiency of weak feature extraction in X-ray weld detection image of ultra-high voltage (UHV) equipment key parts, an automatic feature extraction algorithm is proposed. Firstly, the original weld image is denoised while retaining the characteristic information of weak defects by the proposed monostable stochastic resonance method. Then, binarization is achieved by combining Laplacian edge detection and Otsu threshold segmentation. Finally, the automatic identification of weld defect area is realized based on the sequential traversal of binary tree. Several More >

Guosheng Li¹, Qingquan Lv², Zhenzhen Zhang², Haiying Dong^1,*

Energy Engineering, Vol.120, No.4, pp. 1045-1065, 2023, DOI:10.32604/ee.2023.023770 - 13 February 2023

Abstract Aiming at the problems of output voltage fluctuation and current total harmonic distortion (THD) in the front stage totem-pole bridgeless PFC of two-stage V2G (Vehicle to Grid) vehicle-mounted bi-directional converter, a fuzzy linear active disturbance rejection control strategy for V2G front-stage AC-DC power conversion system is proposed. Firstly, the topological working mode of the totem-pole bridgeless PFC is analyzed, and the mathematical model is established. Combined with the system model and the linear active disturbance rejection theory, a double closed-loop controller is designed with the second-order linear active disturbance rejection control as the voltage outer More > Graphic Abstract

Xinyu Zhou^1,2, Jia Huang^1,2, Yuchen Qian^1,2, Wenli Luo^1,2, Lisha Qi³, Jie Wang³, Zhibin Jiang³, Hao Kang^4,*

Energy Engineering, Vol.120, No.3, pp. 763-774, 2023, DOI:10.32604/ee.2023.025893 - 03 January 2023

Abstract

Due to the characteristics of reservoir formation, the producing level of low permeability reservoir is relatively very low. It is hard to obtain high recovery through conventional development schemes. Considering the tight matrix, complex fracture system, low production level of producers, and low recovery factor of M block in Xinjiang oilfield, it is selected for on-site pilot test of nitrogen foam flooding. Detailed flooding scheme is made and the test results are evaluated respectively both for producers and injectors. The pressure index, filling degree, and fluid injection profile are found to be all improved in injectors

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Asaad H. Sayer¹, Samah Hussein Kadhim¹, Hameed B. Mahood^2,*

Energy Engineering, Vol.120, No.3, pp. 587-596, 2023, DOI:10.32604/ee.2023.025407 - 03 January 2023

Abstract Solar energy applications could be the best alternative to the conventional fuels for the purposes of domestic, water and space heating and some industries in the sunny, arid, and hot areas. In the present study, the performance of an evacuated tube solar heater for water heating for months of February and March was experimentally investigated. This was performed in a hot and arid area (Nasiriya City, South of Iraq). A solar heater with ten evacuated tube solar collectors with a capacity of 100 liter was used in the experiments. Each evacuated tube had a length… More >

Xiaojuan Lu, Mengqiao Chen, Qingbo Zhang^*

Energy Engineering, Vol.120, No.3, pp. 649-664, 2023, DOI:10.32604/ee.2023.025065 - 03 January 2023

Abstract Parallel connection of multiple inverters is an important means to solve the expansion, reserve and protection of distributed power generation, such as photovoltaics. In view of the shortcomings of traditional droop control methods such as weak anti-interference ability, low tracking accuracy of inverter output voltage and serious circulation phenomenon, a finite control set model predictive control (FCS-MPC) strategy of microgrid multi-inverter parallel system based on Mixed Logical Dynamical (MLD) modeling is proposed. Firstly, the MLD modeling method is introduced logical variables, combining discrete events and continuous events to form an overall differential equation, which makes… More > Graphic Abstract

Jun Zhang¹, Xiaobin Li¹, Long Zhao^2,*, Zixin Li¹, Shuo Wang¹, Pan Yao¹, Pengfei Dai²

Energy Engineering, Vol.120, No.3, pp. 617-631, 2023, DOI:10.32604/ee.2022.024855 - 03 January 2023

Abstract In this paper, the research on ACSR temperature of broken strand and fatigue damage after broken strand is carried out. Conduct modeling and Analysis on the conductor through Ansoft Maxwell software. The distribution of magnetic force lines in the cross section of the conductor after strand breaking and the temperature change law of the conductor with the number of broken strands are analyzed. A model based on electromagnetic theory is established to analyze the distribution of magnetic lines of force in the cross section of the conductor after strand breaking and the temperature variation law… More >

Yunlong Ma¹, Junwei Niu^2,*, Bo Xu³, Xingtao Song², Wei Huang², Guoqiang Sun²

Energy Engineering, Vol.120, No.3, pp. 681-700, 2023, DOI:10.32604/ee.2023.024719 - 03 January 2023

Abstract In the power distribution system, the missing or incorrect file of users-transformer relationship (UTR) in low-voltage station area (LVSA) will affect the lean management of the LVSA, and the operation and maintenance of the distribution network. To effectively improve the lean management of LVSA, the paper proposes an identification method for the UTR based on Local Selective Combination in Parallel Outlier Ensembles algorithm (LSCP). Firstly, the voltage data is reconstructed based on the information entropy to highlight the differences in between. Then, the LSCP algorithm combines four base outlier detection algorithms, namely Isolation Forest (I-Forest),… More >

Peng Liao^1,*, Hanlin Liu¹, Yingjie Wang², Neng Liao³

Energy Engineering, Vol.120, No.3, pp. 701-714, 2023, DOI:10.32604/ee.2022.024301 - 03 January 2023

Abstract In the process of my country’s energy transition, the clean energy of hydropower, wind power and photovoltaic power generation has ushered in great development, but due to the randomness and volatility of its output, it has caused a certain waste of clean energy power generation resources. Regarding the purchase and sale of electricity by electricity retailers under the condition of limited clean energy consumption, this paper establishes a quantitative model of clean energy restricted electricity from the perspective of power system supply and demand balance. Then it analyzes the source-charge dual uncertain factors in the… More > Graphic Abstract

Pengwei Yang¹, Yuqi Cao², Jie Tan², Junfa Chen¹, Chao Zhang¹, Yan Wang¹, Haifeng Liang^2,*

Energy Engineering, Vol.120, No.3, pp. 743-762, 2023, DOI:10.32604/ee.2023.024128 - 03 January 2023

Abstract At present, the large-scale access to electric vehicles (EVs) is exerting considerable pressure on the distribution network. Hence, it is particularly important to analyze the capacity of the distribution network to accommodate EVs. To this end, we propose a method for analyzing the EV capacity of the distribution network by considering the composition of the conventional load. First, the analysis and pretreatment methods for the distribution network architecture and conventional load are proposed. Second, the charging behavior of an EV is simulated by combining the Monte Carlo method and the trip chain theory. After obtaining… More >

Zhijie Zheng¹, Song Zhang¹, Xiaolei Zhang², Bo Yang¹, Fang Yan³, Xiaoning Ge^3,*

Energy Engineering, Vol.120, No.3, pp. 633-647, 2023, DOI:10.32604/ee.2022.024081 - 03 January 2023

Abstract The DC distribution network system equipped with a large number of power electronic equipment exhibits weak damping characteristics and is prone to low-frequency and high-frequency unstable oscillations. The current interpretation of the oscillation mechanism has not been unified. Firstly, this paper established the complete state-space model of the distribution system consisting of a large number of electric vehicles, characteristic equation of the distribution network system is derived by establishing a state-space model, and simplified reduced-order equations describing the low-frequency oscillation and the high-frequency oscillation are obtained. Secondly, based on eigenvalue analysis, the oscillation modes and More >