Yu Xiao^1,2, Kai Li^1,2, Hongqiao Huang^1,2, Haibo Tan^1,2, Hua Li^3,*

Energy Engineering, Vol.120, No.2, pp. 511-527, 2023, DOI:10.32604/ee.2023.022750

Abstract The analysis of the loss of distributed photovoltaic power generation systems involves the interests of energy users, energy-saving service companies, and power grid companies, so it has always been the focus of the industry and society in some manner or another. However, the related analysis for an actual case that considers different cooperative corporations’ benefits is lacking in the presently available literature. This paper takes the distributed rooftop photovoltaic power generation project in an industrial park as the object, studies the analysis and calculation methods of line loss and transformer loss, analyzes the change of transformer loss under different temperatures… More >

Yashar Aryanfar^1,*, Jorge Luis García Alcaraz²

Energy Engineering, Vol.120, No.2, pp. 263-275, 2023, DOI:10.32604/ee.2023.022587

Abstract The usage of renewable energies, including geothermal energy, is expanding rapidly worldwide. The low efficiency of geothermal cycles has consistently highlighted the importance of recovering heat loss for these cycles. This paper proposes a combined power generation cycle (single flash geothermal cycle with trans-critical CO₂ cycle) and simulates in the EES (Engineering Equation Solver) software. The results show that the design parameters of the proposed system are significantly improved compared to the BASIC single flash cycle. Then, the proposed approach is optimized using the genetic algorithm and the Nelder-Mead Simplex method. Separator pressure, steam turbine output pressure, and CO₂ turbine… More > Graphic Abstract

Xiangfei Li, Yang Yin, Yang Zhou, Wenchang Liu, Kaihui Zhao^*

Energy Engineering, Vol.120, No.2, pp. 277-297, 2023, DOI:10.32604/ee.2023.022461

Abstract This paper presents a novel non-singular fast terminal sliding mode control (NFTSMC) based on the deep flux weakening switching point tracking method in order to improve the control performance of permanent interior magnet synchronous motor (IPMSM) drive systems. The mathematical model of flux weakening (FW) control is established, and the deep flux weakening switching point is calculated accurately by analyzing the relationship between the torque curve and voltage decline curve. Next, a second-order NFTSMC is designed for the speed loop controller to ensure that the system converges to the equilibrium state in finite time. Then, an extended sliding mode disturbance… More > Graphic Abstract

Ahmed Al-Abri¹, Kenneth E. Okedu^1,2,*

Energy Engineering, Vol.120, No.2, pp. 409-423, 2023, DOI:10.32604/ee.2023.020375

Abstract Lately, in modern smart power grids, energy demand for accurate forecast of electricity is gaining attention, with increased interest of research. This is due to the fact that a good energy demand forecast would lead to proper responses for electricity demand. In addition, proper energy demand forecast would ensure efficient planning of the electricity industry and is critical in the scheduling of the power grid capacity and management of the entire power network. As most power systems are been deregulated and with the rapid introduction and development of smart-metering technologies in Oman, new opportunities may arise considering the efficiency and… More > Graphic Abstract

Ying He, Yongshuang Wen^*, Xuemei Huang, Leian Zhang, Rujun Song, Chang Li

Energy Engineering, Vol.120, No.2, pp. 445-459, 2023, DOI:10.32604/ee.2022.022223

Abstract In order to study the mechanical properties of the heterogeneous core plate of the wind turbine blade, a modeling method of the core plate based on displacement field variables is proposed. Firstly, the wind turbine blade core plate was modeled according to the theory of modeling heterogeneous material characteristics. Secondly, the three-point bending finite element model of the wind turbine blade core plate was solved by the display dynamic equation to obtain the deformation pattern and force-deformation relationship of the core plate. Finally, the three-point bending static test was conducted to compare with the finite element analysis. The test results… More >

Chang Liu¹, Bo Luo¹, Wei Wang¹, Hongyuan Gao¹, Zhixun Wang², Hongfa Ding^3,*, Mengqi Yu⁴, Yongquan Peng⁵

Energy Engineering, Vol.120, No.2, pp. 541-559, 2023, DOI:10.32604/ee.2022.022610

Abstract Building structures themselves are one of the key areas of urban energy consumption, therefore, are a major source of greenhouse gas emissions. With this understood, the carbon trading market is gradually expanding to the building sector to control greenhouse gas emissions. Hence, to balance the interests of the environment and the building users, this paper proposes an optimal operation scheme for the photovoltaic, energy storage system, and flexible building power system (PEFB), considering the combined benefit of building. Based on the model of conventional photovoltaic (PV) and energy storage system (ESS), the mathematical optimization model of the system is proposed… More >

Baodong Li^*

Energy Engineering, Vol.120, No.2, pp. 461-481, 2023, DOI:10.32604/ee.2022.021877

Abstract The optimal operation of microgrids is of great significance for the sake of efficient and economical management of its energy resources. The microgrid energy management system should plan to operate the microgrid while simultaneously considering the electric and thermal load. The present study proposes energy management to minimize the costs of operating an industrial microgrid. In fact, planning for energy supply is among the critical issues that distribution companies deal with daily in the competitive environment. A distribution company usually meets customer (end customer) demands by purchasing energy from a wholesale market. Given the load curtailment, distribution companies have more… More >

Yajing Zhang¹, Chaoyang Song², Zhiguo Li^2,*

Energy Engineering, Vol.120, No.2, pp. 501-510, 2023, DOI:10.32604/ee.2022.021423

Abstract To overcome the problems of natural decreases in power quality, and to eliminate wind speed fluctuation due to wind shear and tower shadow effect arising from wind turbine structural parameters, an improved prediction model accounting for the dual effect of wind shear and tower shadow is, in this paper, built. Compared to the conventional prediction model, the proposed model contains a new constraint condition, which makes the disturbance term caused by the tower shadow effect always negative so that the prediction result is closer to the actual situation. Furthermore, wind turbine structural parameters such as hub height, rotor diameter, the… More > Graphic Abstract

Saeed Akbari¹, Seyed Saeed Fazel^1,*, Hamed Hashemi-Dezaki^2,3

Energy Engineering, Vol.120, No.1, pp. 69-86, 2023, DOI:10.32604/ee.2022.024121

Abstract The networking of microgrids has received significant attention in the form of a smart grid. In this paper, a set of smart railway stations, which is assumed as microgrids, is connected together. It has been tried to manage the energy exchanged between the networked microgrids to reduce received energy from the utility grid. Also, the operational costs of stations under various conditions decrease by applying the proposed method. The smart railway stations are studied in the presence of photovoltaic (PV) units, energy storage systems (ESSs), and regenerative braking strategies. Studying regenerative braking is one of the essential contributions. Moreover, the… More > Graphic Abstract

Dahai Zhang^*, Chuanjian Wu, Jinghan He

Energy Engineering, Vol.120, No.1, pp. 1-21, 2023, DOI:10.32604/ee.2022.023304

Abstract Line-commutated converter-voltage source converter (LCC-VSC) power transmission technology does not have the problem of communication failure very usually. It therefore can support the long-distance, long-capacity transmission of electric energy. However, factors such as topology, control strategy, and short-circuit capacities make the traditional protection principles not fully applicable to LCC-VSC hybrid transmission systems. To enhance the reliability of hybrid DC systems, a single-ended principle based on transmission coefficients is proposed and produced. First, the equivalent circuit of the LCC-VSC hybrid DC system is analyzed and the expression of the first traveling wave is deduced accordingly. Then, the concept of multi-frequency transmission… More >