Zhixian Qi^1,2,*, Shuohe Wang^1,2, Qiang Xue^1,2, Haiting Mi³, Jian Wang^1,2

Energy Engineering, Vol.120, No.9, pp. 2059-2077, 2023, DOI:10.32604/ee.2023.028595 - 03 August 2023

Abstract A current identification method based on optimized variational mode decomposition (VMD) and sample entropy (SampEn) is proposed in order to solve the problem that the main protection of the urban rail transit DC feeder cannot distinguish between train charging current and remote short circuit current. This method uses the principle of energy difference to optimize the optimal mode decomposition number k of VMD; the optimal VMD for DC feeder current is decomposed into the intrinsic modal function (IMF) of different frequency bands. The sample entropy algorithm is used to perform feature extraction of each IMF, and More >

Morris Kayitare^1,2,*, Gace Athanase Dalson^2,3, Al-Mas Sendegeyad⁴

Energy Engineering, Vol.120, No.9, pp. 2155-2175, 2023, DOI:10.32604/ee.2023.028559 - 03 August 2023

Abstract Standalone Solar PV systems have been vital in the improvement of access to energy in many countries. However, given the large cost of solar PV plants’ components, in developing countries, there is a dear need for such components to be subsidised and incentivised for the consumers to afford the produced energy. Moreover, there is a need for optimal sizing of the solar PV plants taking into account the solar information, energy requirement for various activities, and economic conditions in the off-grid regions in Rwanda. This study aims to develop optimally sized solar PV plants suited… More > Graphic Abstract

Huanan Yu¹, Gang Han^1,*, Hansong Luo², He Wang¹

Energy Engineering, Vol.120, No.9, pp. 2029-2057, 2023, DOI:10.32604/ee.2023.028365 - 03 August 2023

Abstract Aiming at the problem that most of the cables in the power collection system of offshore wind farms are buried deep in the seabed, which makes it difficult to detect faults, this paper proposes a two-step fault location method based on compressed sensing and ranging equation. The first step is to determine the fault zone through compressed sensing, and improve the data measurement, dictionary design and algorithm reconstruction: Firstly, the phase-locked loop trigonometric function method is used to suppress the spike phenomenon when extracting the fault voltage, so that the extracted voltage value will not… More >

Liang Hu, Hailong Yu^*, Liuyang Huang, Yayun Xu, Xulei Wu, Yunlan Sun, Baozhong Zhu

Energy Engineering, Vol.120, No.9, pp. 1963-1977, 2023, DOI:10.32604/ee.2023.027897 - 03 August 2023

Abstract In this paper, based on Fluent software, a five-nozzle gasifier reactor was established to simulate the gasification process of oil-based drill cuttings coal-water slurry. The influence of concentration and oxygen/carbon atomic ratio on the gasification process of oil-based drill cuttings coal-water slurry was investigated. The results show that when the oxygen flow is constant, the outlet temperature of gasifier decreases, the content of effective gas increases, and the carbon conversion rate decreases with the increase of concentration; When the ratio of oxygen to carbon atoms is constant, the effective gas content rises and the temperature More > Graphic Abstract

Uwem O. Ikitde¹, Abayomi A. Adebiyi^1,*, Innocent E. Davidson², Ayodeji S. Akinyemi¹

Energy Engineering, Vol.120, No.9, pp. 1939-1961, 2023, DOI:10.32604/ee.2023.027574 - 03 August 2023

Abstract The integration of solar and wind energy into the electrical grid has received global research attention due to their unpredictable characteristics. Because wind energy varies across all timescales of utility activity, renewable energy generation should be supplemented and enhanced, from real-time, minute-to-minute variations to annual alterations influencing long-term strategy. Wind energy generation does not only fluctuate but is also challenging to accurately forecast the timeframes of significance to electricity decision makers; day-ahead and long-term making plans of framework sufficiency such as meeting the network peak load annually. A utility that integrates wind and solar energy… More >

Xu Yang^1,2, Jing Zhang^1,2, Chuanxian Luo^1,2, Qinqing Huang^1,2, Hui Xu^1,2, Guozhi Zhang^1,2,*

Energy Engineering, Vol.120, No.9, pp. 2115-2132, 2023, DOI:10.32604/ee.2023.027198 - 03 August 2023

Abstract In response to the problem of frequent leakage and false alarm of partial discharge insulation defects in GIS, this paper conducts experimental research on intermittent discharge characteristics of common solid insulation defects in GIS. Using true GIS to build a multi-source testing platform for intermittent discharge of solid insulation defects, and using pulse current method, ultra-high frequency method, ultrasonic method, and gas characteristic component detection method to study the variation law of intermittent discharge characteristics of solid insulation defects. The results show that: the intermittent discharge state of metal fouling defects on the solid insulation… More >

Wei Zhang¹, Bin Ji², Ping He¹, Nanqin Wang¹, Yuwei Wang¹, Mengzhe Zhang^2,*

Energy Engineering, Vol.120, No.9, pp. 2177-2192, 2023, DOI:10.32604/ee.2023.026504 - 03 August 2023

Abstract Power flow calculation is the basis of power grid planning and many system analysis tasks require convergent power flow conditions. To address the unsolvable power flow problem caused by the reactive power imbalance, a method for adjusting reactive power flow convergence based on deep reinforcement learning is proposed. The deep reinforcement learning method takes switching parallel reactive compensation as the action space and sets the reward value based on the power flow convergence and reactive power adjustment. For the non-convergence power flow, the 500 kV nodes with reactive power compensation devices on the low-voltage side More >

Jingxiao Han¹, Chuanzhao Zhang², Lu Wang^3,*, Zengjun Chang¹, Qing Zhao¹, Ying Shi⁴, Jiarui Wu⁵, Xiangfei Kong³

Energy Engineering, Vol.120, No.9, pp. 1991-2011, 2023, DOI:10.32604/ee.2023.029749 - 31 July 2023

Abstract For heating systems based on electricity storage coupled with solar energy and an air source heat pump (ECSA), choosing the appropriate combination of heat sources according to local conditions is the key to improving economic efficiency. In this paper, four cities in three climatic regions in China were selected, namely Nanjing in the hot summer and cold winter region, Tianjin in the cold region, Shenyang and Harbin in the severe cold winter region. The levelized cost of heat (LCOH) was used as the economic evaluation index, and the energy consumption and emissions of different pollutants… More > Graphic Abstract

Jialuo Rong^1,2, Shuixiang Xie^3,4, Huijing Geng⁵, Hao Hu^1,2, Shanfa Tang^1,2,*, Yuanpeng Cheng^1,2,*

Energy Engineering, Vol.120, No.8, pp. 1899-1917, 2023, DOI:10.32604/ee.2023.027650 - 05 June 2023

Abstract Due to its extensive use in shale gas exploration and development, oil-based drilling fluids generate large amounts of oil-bearing drill cuttings during the drilling process. The large amount of oil-bearing drill cuttings generated during the drilling process can lead to serious secondary contamination. In this study, a wetting agent FSC-6 with good hydrophobic and oleophobic properties was synthesized to construct an efficient oil removal system. For the first time, the mechanism of this system was analyzed by using the theory of adhesion function, interfacial tension and wettability. At the same time, a combined acoustic-chemical treatment More >

Zhiyuan Yao^1,2,3, Jing Sun^1,2,3,*, Dehua Liu^1,2,3

Energy Engineering, Vol.120, No.8, pp. 1853-1866, 2023, DOI:10.32604/ee.2023.025846 - 05 June 2023

Abstract Shale gas reservoirs have poor physical properties and a large number of micro-nano pores have been developed. Shale gas wells have no natural productivity and need fracturing reconstruction measures to put into production. However, the fracturing fluid will enter the reservoir space of shale matrix after fracturing and affect the production of shale gas. At present, there is no consensus on the influence of fracturing fluid retention on gas well production. Based on this, the paper adopts gas molecular transport analyzer to carry out experimental research on the influence of fracturing fluid on shale gas… More >