Xiangjian Shi^1,*, Teng Liu², Wei Mu², Jianfeng Zhao¹

Energy Engineering, Vol.119, No.5, pp. 1843-1860, 2022, DOI:10.32604/ee.2022.020787 - 21 July 2022

Abstract A microgrid (MG) refers to a set of loads, generation resources and energy storage systems acting as a controllable load or a generator to supply power and heating to a local area. The MG-generated power management is a central topic for MG design and operation. The existence of dispersed generation (DG) resources has faced MG management with new issues. Depending on the level of exchanges between an MG and the main grid, the MG operation states can be divided into independent or grid-connected ones. Energy management in MGs aims to supply power at the lowest… More >

Haitao Wang^1,2, Yongli Liu^1,*, Bin Shen¹, Mengxuan Ren¹, Qiyuan Shan¹

Energy Engineering, Vol.119, No.5, pp. 2031-2047, 2022, DOI:10.32604/ee.2022.020776 - 21 July 2022

Abstract The goal of this study was to investigate coal quality features and their relationship to coal spontaneous combustion characteristics in multi-seam coal mines to better predict when coal spontaneous combustion is likely to occur. To that end, coal samples of various particle sizes were obtained from five coal seams (Nos. 6, 8, 9, 12 and 20) in the Shuangyashan City Xin’an Coal Mine. The samples were then respectively heated using a temperature programming system to observe and compare similarities and differences in the spontaneous combustion process of different particle sizes in response to rising temperature.… More >

Xucheng Chang^1,*, Bing Kong², Yong Li¹, Gaofeng Ren¹, Chao Zhang¹, Zhenghe Wang¹

Energy Engineering, Vol.119, No.5, pp. 1941-1966, 2022, DOI:10.32604/ee.2022.020698 - 21 July 2022

Abstract For purpose of achieving the desired thermal comfort level and reducing the economic cost of maintaining the thermal comfort of green residential building, an energy efficient thermal comfort control strategy based on economic model predictive control (EMPC) for green residential buildings which adopts household heat metering is presented. Firstly, the nonlinear thermal comfort model of heating room is analyzed and obtained. A practical nonlinear thermal comfort prediction model is obtained by using an approximation method. Then, the economic cost function and optimization problem of energy-saving under the necessary thermal comfort requirements are constructed to realize… More >

Jun Zhao¹, Shuguo Gao¹, Yunpeng Liu^2,3, Quan Wang^2,*, Ziqiang Xu², Yuan Tian¹, Lu Sun¹

Energy Engineering, Vol.119, No.5, pp. 1811-1828, 2022, DOI:10.32604/ee.2022.020490 - 21 July 2022

Abstract Aiming at the problem of abnormal data generated by a power transformer on-line monitoring system due to the influences of transformer operation state change, external environmental interference, communication interruption, and other factors, a method of anomaly recognition and differentiation for monitoring data was proposed. Firstly, the empirical wavelet transform (EWT) and the autoregressive integrated moving average (ARIMA) model were used for time series modelling of monitoring data to obtain the residual sequence reflecting the anomaly monitoring data value, and then the isolation forest algorithm was used to identify the abnormal information, and the monitoring sequence More >

Jia’an Xie^1,*, Yurong Wang², Guobin Jin³, Mucheng Wu¹

Energy Engineering, Vol.119, No.5, pp. 1797-1809, 2022, DOI:10.32604/ee.2022.020344 - 21 July 2022

Abstract In order to effectively solve the dead-zone and low-precision of T-shaped transmission line fault location, a new T-shaped transmission line fault location algorithm based on phase-angle jump checking is proposed in this paper. Firstly, the 3-terminal synchronous fundamental positive sequence voltage and current phasors are extracted and substituted into the fault branch distance function to realize the selection of fault branch when the fault occurs; Secondly, use the condition of the fundamental positive sequence voltage phasor at the fault point is equal to calculate all roots (including real root and virtual roots); Finally, the phase-angle More >

Wenlu Ji, Yong Wang^*, Xing Deng, Ming Zhang, Ting Ye

Energy Engineering, Vol.119, No.5, pp. 1967-1983, 2022, DOI:10.32604/ee.2022.020011 - 21 July 2022

Abstract Virtual power plants can effectively integrate different types of distributed energy resources, which have become a new operation mode with substantial advantages such as high flexibility, adaptability, and economy. This paper proposes a distributionally robust optimal dispatch approach for virtual power plants to determine an optimal day-ahead dispatch under uncertainties of renewable energy sources. The proposed distributionally robust approach characterizes probability distributions of renewable power output by moments. In this regard, the faults of stochastic optimization and traditional robust optimization can be overcome. Firstly, a second-order cone-based ambiguity set that incorporates the first and second… More >

Nada Yamoul^1,*, Latifa Dlimi¹, Baraka Achraf Chakir²

Energy Engineering, Vol.119, No.5, pp. 2135-2148, 2022, DOI:10.32604/ee.2022.020005 - 21 July 2022

Abstract The building sector is one of the main energy-consuming sectors in Morocco. In fact, it accounts for 33% of the final consumption of energy and records a high increase in the annual consumption of energy caused by further planned large-scale projects. Indeed, the energy consumption of the building sector is experiencing a significant acceleration justified by the rapid need for the development of housing stock, wich is estimated at an average increase of 1,5% per year; furthermore, tant is an estimated increase of about 6,4%. In this sense, building constitutes an important potential source for… More >

Wenjun Wei^1,2, Hao Liang^1,*

Energy Engineering, Vol.119, No.5, pp. 2065-2080, 2022, DOI:10.32604/ee.2022.020002 - 21 July 2022

Abstract Droop control is one of the main control strategies of islanded microgrid (MG), but the droop control cannot achieve reasonable power distribution of microgrid, resulting in frequency and voltage deviation from the rating value, which needs the upper control link to eliminate the deviation. However, at present, most layered control requires a centralized control center, which excessively relies on microgrid central controller (MGCC) and real-time communication among distributed generation (DG), which has certain limitations. To solve the above problems, this paper proposes a hierarchical distributed power and power quality optimization strategy based on multi-agent finite… More >

Felipe Mercês Biglia¹, Raquel da Cunha Ribeiro da Silva², Fátima de Moraes Lino³, Kamal Abdel Radi Ismail³, Thiago Antonini Alves^4,*

Energy Engineering, Vol.119, No.5, pp. 1771-1788, 2022, DOI:10.32604/ee.2022.019625 - 21 July 2022

Abstract The frost growth on cold surfaces in evaporators is an undesirable phenomenon which becomes a problem for the thermal efficiency of the refrigeration systems because the ice layer acts as a thermal insulation, drastically reducing the rate of heat transfer in the system. Its accumulation implies an increase in energy demand and a decrease in the performance of various components involved in the refrigeration process, reducing its efficiency and making it necessary to periodically remove the frost, resulting in expenses for the defrost process. In the present work, a numerical-experimental analysis was performed in order… More >

Wenpeng Guo^1,2, Yongtu Liang^1,*

Energy Engineering, Vol.119, No.5, pp. 2049-2064, 2022, DOI:10.32604/ee.2022.019526 - 21 July 2022

Abstract In this paper, the transportation economy of two heated crude oil pipelines laid in one ditch is analyzed by taking into account the influence of operating temperature, interval between two pipelines, and distance between two heating stations on the heating energy consumption. To analyze the transportation economy, the two heated crude oil pipelines laid in one ditch are simulated under four operating conditions based on an unstructured finite volume method. Compared with laying two crude oil pipelines separately in two ditches, the results attest notably higher soil temperature, meaning reduced heat dissipation of each pipeline… More >