Quanchun Yan^1,2,*, Chao Yuan¹, Wen Gu¹, Yanan Liu¹, Yiming Tang¹

Energy Engineering, Vol.120, No.1, pp. 49-68, 2023, DOI:10.32604/ee.2022.018555

Abstract In order to solve the problems of rotor overvoltage, overcurrent and DC side voltage rise caused by grid voltage drops, a coordinated control strategy based on symmetrical and asymmetrical low voltage ride through of rotor side converter of the doubly-fed generator is proposed. When the power grid voltage drops symmetrically, the generator approximate equation under steady-state conditions is no longer applicable. Considering the dynamic process of stator current excitation, according to the change of stator flux and the depth of voltage drop, the system can dynamically provide reactive power support for parallel nodes and suppress the rise of DC side… More >

Lihu Cao^1,2, Jinsheng Sun^1,*, Bo Zhang^3,*, Nu Lu⁴, Yuqiang Xu¹

Energy Engineering, Vol.120, No.1, pp. 35-48, 2023, DOI:10.32604/ee.2022.022867

Abstract In gas storage or high-pressure gas wells, annular pressure is an unavoidable threat to safe, long-term resource production. The more complex situation, however, is multiple annular pressure, which means annular pressure happens in not only one annulus but two or more. Such a situation brings serious challenges to the identification of well integrity. However, few researches analyze the phenomenon of multiple annular pressure. Therefore, this paper studies the mechanism of multi-annular pressure to provide a foundation for its prevention and diagnosis. Firstly, the multi-annular pressure is classified according to the mechanism and field data. Then the failure mechanism and function… More >

Edwin N. Mbinkar^1,*, Derek Ajesam Asoh^1,2,3, Jerome Ndam Mungwe³, Livinus Songyuh⁴, Emmanuel Lamfu⁵

Energy Engineering, Vol.119, No.6, pp. 2637-2654, 2022, DOI:10.32604/ee.2022.023419

Abstract An electricity market is a trading platform provided by the actors in the electricity sector to sell and buy electricity while maintaining the stability of the transmission network and minimizing energy losses. The management of electrical energy for rational use consists of all the operations that the consumers can carry out in order to minimize their electricity bill, while the producers optimize their benefits and the transmission infrastructure. The reduction of active and reactive power consumption and the smoothing of daily and yearly load profiles are the main objectives in this work. Many developed countries already have properly functioning electricity… More > Graphic Abstract

Akinyemi Ayodeji Stephen^*, Kabeya Musasa, Innocent Ewean Davidson

Energy Engineering, Vol.119, No.6, pp. 2711-2744, 2022, DOI:10.32604/ee.2022.023069

Abstract The occurrence of distortion and over voltage at the Point of Common Coupling (PCC) of Renewable Distributed Generation (RDG) limits its penetration levels to the power system and the RDG integration is expected to play a crucial role in power system transformation. For its penetrations to be sustained without disconnection from the system, there must be a solution to the voltage rise, distortion, unbalanced current and grid reactive power control strategy at PCC. It is an IEEE-1547 requirement that RDG integration to the power system should be regulated at PCC to avoid disconnection from the network due to power quality… More > Graphic Abstract

David Graf, Philipp Neuner, Reinhard Rauch^*

Energy Engineering, Vol.119, No.6, pp. 2169-2192, 2022, DOI:10.32604/ee.2022.022759

Abstract The number of annually registered internal-combustion vehicles still exceeds electric-driven ones in most regions, e.g., Germany. Ambitious goals are disclosed with the European Green Deal, which calls for new technical approaches and greenhouse gas neutral transition technologies. Such bridging technologies are synthetic fuels for the transportation sector, e.g., using the bioliq^® process for a CO₂-neutral gasoline supply. Fuels must meet the applicable national standards to be used in existing engines. Petrochemical parameters can be variably adapted to their requirements by hydroprocessing. In this work, we considered the upgrading of aromatic-rich DTG gasoline from the bioliq^® process. The heavy gasoline was… More >

Rasool M. Imran^1,2,*, Mohammed R. Saeed¹, Mohammed Amer Mohammed³, Osama A. Suhry³, Ihsan H. Abdulqadder⁴, Hasan Wahhab Salih⁵, Mohammed R. Almallah⁶, Firas M. F. Flaih³

Energy Engineering, Vol.119, No.6, pp. 2447-2467, 2022, DOI:10.32604/ee.2022.021871

Abstract

Usually, rural areas can be electrified via three-phase distribution transformers with relatively large capacities. In such areas, low voltage lines are used for long distances, which cause power losses and voltage drop for different types of consumers. Reducing losses and improving voltage profiles in rural distribution networks are significant challenges for electricity distribution companies. However different solutions were proposed in the literature to overcome these challenges, most of them face difficulties when applied in the conventional distribution network. To address the above issues, an applicable solution is proposed in this paper by installing a number of small-capacity distribution transformers instead… More >

Zheng Wang^*, Shangke Liu, Yanli Xiao, Ye Wan, Bin Bai

Energy Engineering, Vol.119, No.6, pp. 2655-2679, 2022, DOI:10.32604/ee.2022.021843

Abstract Technology advancement and the global tendency to use renewable energy in distributed generation units in the distribution network have been proposed as sources of energy supply. Despite the complexity of their protection, as well as the operation of distributed generation resources in the distribution network, factors such as improving reliability, increasing production capacity of the distribution network, stabilizing the voltage of the distribution network, reducing peak clipping losses, as well as economic and environmental considerations, have expanded the influence of distributed generation (DG) resources in the distribution network. The location of DG sources and their capacity are the key factors… More >

Baoge Zhang¹, Shanyan Ping^1,*, Haoliang Shi², Yi Long¹, Boxiang Wu¹, Yuemin Jiao¹

Energy Engineering, Vol.119, No.6, pp. 2347-2367, 2022, DOI:10.32604/ee.2022.021693

Abstract Renewable energy is connected to the grid through the inverter, which in turn reduces the inertia and stability of the power grid itself. The traditional grid-connected inverter does not have the function of voltage regulation and frequency regulation and can therefore no longer adapt to the new development. The virtual synchronous generator (VSG) has the function of voltage regulation and frequency regulation, which has more prominent advantages than traditional inverters. Based on the principle of VSG, the relationship between the frequency characteristics and the energy storage capacity of the feedforward branch-based virtual synchronous machine (FVSG) is derived when the input… More >

Rongxin Zhang^1,*, Chengying Yang^2,3, Xuetao Li¹

Energy Engineering, Vol.119, No.6, pp. 2489-2511, 2022, DOI:10.32604/ee.2022.021517

Abstract Buildings are the main energy consumers across the world, especially in urban communities. Building smartization, or the smartification of housing, therefore, is a major step towards energy grid smartization too. By controlling the energy consumption of lighting, heating, and cooling systems, energy consumption can be optimized. All or some part of the energy consumed in future smart buildings must be supplied by renewable energy sources (RES), which mitigates environmental impacts and reduces peak demand for electrical energy. In this paper, a new optimization algorithm is applied to solve the optimal energy consumption problem by considering the electric vehicles and demand… More >

Yanliang Qiu^1,2, Bin Xiong^1,2, Zhe Hou^1,2,*, Lin Luo³

Energy Engineering, Vol.119, No.6, pp. 2243-2254, 2022, DOI:10.32604/ee.2022.021322

Abstract The shrink fit retaining ring is currently the easiest to install and the most widely used end fixed for structure AC excitation variable speed generator-motor rotor end windings. However, the current research on the effect of high strength sealing on the ventilation and heat dissipation performance of the end is not enough. In this paper, based on the actual structural parameters and periodic symmetry simplification, the three-dimensional coupled calculation model of fluid field and temperature field is established. After solving the fluid and thermal equations, the influence of the length of rotor support block, the height of rotor support block,… More >