Miaohong Su¹, Haiying Dong^1,2,*, Kaiqi Liu¹, Weiwei Zou¹

Energy Engineering, Vol.117, No.6, pp. 439-452, 2020, DOI:10.32604/EE.2020.011805 - 16 October 2020

Abstract A subsynchronous oscillation suppression strategy based on self-adaptive auto disturbance rejection proportional integral controller is proposed for doublyfed induction generator-based wind farm integrated into grid through voltage source converter based multi-terminal direct current. In this strategy, the nonlinear PI controller is constructed by fal function to replace the traditional linear PI controller, and then the tracking differentiator is used to arrange the appropriate transition process in combination with the idea of active disturbance rejection control, and the self-adaptive auto disturbance rejection proportional integral controller is designed. By applying the controller to the inner loop of the… More >

Yunxiang Guo¹, Cheng Lu^1,2, Feng Yu¹, Liang Hua¹, Xinsong Zhang^1,*

Energy Engineering, Vol.117, No.6, pp. 429-438, 2020, DOI:10.32604/EE.2020.011673 - 16 October 2020

Abstract Nanocrystalline core is often adopted in high-power medium-frequency transformer, whose excitation voltage is usually a rectangular wave with an adjustable duty ratio. In this paper, several kinds of methods are proposed for core loss calculation under non-sinusoidal voltage excitation by modifying the original Steinmetz equation (OSE). Firstly, these correction methods are compared in theory, and their analytical equations under rectangular voltage with an adjustable duty ratio are deduced. Then, a hysteresis loop measurement system is established to measure the core loss density of a nanocrystalline core. Based on the measured results of the core loss More >

Yuhao Jia¹, Bin Cheng^1,2,*, Xiyang Li^1,2, Hui Zhang^1,2, Yinglong Dong¹

Energy Engineering, Vol.117, No.6, pp. 413-427, 2020, DOI:10.32604/EE.2020.012019 - 16 October 2020

Abstract In order to study the effect of icing on the wind turbine blade tip speed ratio and wind energy utilization coefficient under working conditions, it is important to better understand the growth characteristics of wind turbine blade icing under natural conditions. In this paper, the icing test of the NACA4412 airfoil wind turbine was carried out using the natural low temperature wind turbine icing test system. An evaluation model of icing degree was established, and the influence of wind speed and icing degree on the performance parameters of wind turbines was compared and analyzed. It… More >

Asaad H. Sayer¹, Hameed B. Mahood^2,*

Energy Engineering, Vol.117, No.6, pp. 367-379, 2020, DOI:10.32604/EE.2020.011156 - 16 October 2020

Abstract Salinity gradient solar ponds (SGSPs) provide a tremendous way to collect and store solar radiation as thermal energy, and can help meet the critical need for sustainable ways of producing fresh water. However, surface evaporation results in the loss of both water and heat. This study therefore theoretically investigates the effect on temperatures within an SGSP when its surface is covered with a layer of air encased in a nylon bag. An earlier SGSP model was slightly modified to add the air layer and to estimate the temperature distributions of the upper layer or the… More >

Tanzhong Fu^1,2,3, Yu Xue^1,*, Tancai Xia¹, Wang Jing¹, De Gejirifu¹

Energy Engineering, Vol.117, No.6, pp. 397-411, 2020, DOI:10.32604/EE.2020.011633 - 16 October 2020

Abstract To further study the impact of renewable energy penetration on the technical transformation of distribution networks. Based on the output power characteristics of wind power and photovoltaics, a renewable energy grid-connected capacity model and a distribution network full cost-benefit model were constructed. Based on this, to maximize the comprehensive income of the distribution network and the renewable energy penetration rate, to establish the technical reform optimization model and search for the optimal solution through the improved NSGA-II algorithm. Finally, the effectiveness of the proposed model was verified by setting up three scenarios of simultaneous wind More >

Shafiqur Rehman¹, Umar T. Salman^2,*, Luai M. Alhems¹

Energy Engineering, Vol.117, No.6, pp. 343-365, 2020, DOI:10.32604/EE.2020.011471 - 16 October 2020

Abstract Renewable energy has received much attention in the last few decades and more investment is being attracted across the world to boost its contribution towards the existing energy mix. In the Kingdom of Saudi Arabia (KSA), many studies have been conducted on the potential of renewable energy sources (RES), such as wind, solar, and geothermal. Many of these studies have revealed that the Kingdom is blessed with an abundance of RES with wind energy being the best after solar. This paper presents an analysis of windfarm distributed generation (WFDG) for energy management strategy in the… More >

Yanan Zhang^1,*, Lin Ouyang², Qinqin Li², Haichen Ju²

Journal on Big Data, Vol.2, No.3, pp. 125-133, 2020, DOI:10.32604/jbd.2020.012879 - 13 October 2020

Abstract Under the traditional dynamic model, the conventional method for solving the rotation angle of a rigid body is to use the fixed-axis rotation law of the rigid body, but the known rotation shaft position must be used as a prerequisite. In practical work, for the rotation of a rigid body under multiple forces, solving the shaft is often a difficult problem. In this paper, we consider the rigid body of the disc is subjected to the force of uneven magnitude from multiple angles, the position of the rotating shaft is obtained by iterative inversion through… More >

Xianghui Lu¹, Junliang Fan², Lifeng Wu^1,*, Jianhua Dong³

CMES-Computer Modeling in Engineering & Sciences, Vol.125, No.2, pp. 699-723, 2020, DOI:10.32604/cmes.2020.011004 - 12 October 2020

Abstract It is important for regional water resources management to know the agricultural water consumption information several months in advance. Forecasting reference evapotranspiration (ET₀) in the next few months is important for irrigation and reservoir management. Studies on forecasting of multiple-month ahead ET₀ using machine learning models have not been reported yet. Besides, machine learning models such as the XGBoost model has multiple parameters that need to be tuned, and traditional methods can get stuck in a regional optimal solution and fail to obtain a global optimal solution. This study investigated the performance of the hybrid extreme… More >

Zhiyuan Liu^1,2, Xin Tan², Xiaobo Liu^1,2, Pingan Chen^1,2, Ke Yi^1,2, Tianzhi Yang^1,2, Qiao Ni^3,4, Lin Wang^3,4,*

CMES-Computer Modeling in Engineering & Sciences, Vol.125, No.2, pp. 495-514, 2020, DOI:10.32604/cmes.2020.012030 - 12 October 2020

Abstract Cantilevered pipe conveying fluid may become unstable and flutter instability would occur when the velocity of the fluid flow in the pipe exceeds a critical value. In the present study, the theoretical model of a cantilevered fluid-conveying pipe attached by an inerter-based dynamic vibration absorber (IDVA) is proposed and the stability of this dynamical system is explored. Based on linear governing equations of the pipe and the IDVA, the effects of damping coefficient, weight, inerter, location and spring stiffness of the IDVA on the critical flow velocities of the pipe system is examined. It is More >

Jungang Jia^*

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.5, pp. 919-933, 2020, DOI:10.32604/fdmp.2020.09566 - 09 October 2020

Abstract To solve the problem of temperature rise caused by the high power density of high-speed permanent magnet synchronous traction motors, the temperature rise of various components in the motor is analyzed by coupling the equivalent thermal circuit method and computational fluid dynamics. Also, a cooling strategy is proposed to solve the problem of temperature rise, which is expected to prolong the service life of these devices. First, the theoretical bases of the approaches used to study heat transfer and fluid mechanics are discussed, then the fluid flow for the considered motor is analyzed, and the… More >