An MJ-class superconducting magnetic energy storage (SMES) system has a wide range of potential applications in electric power systems. The composite HTS conductor, which has the advantages of carrying large critical currents and withstanding high magnetic fields, is suitable for winding an MJclass magnet coil. However, the Lorentz force of an HTS wire is so large that its induced mechanical stresses should be examined to ensure that the magnet is in good condition. By means of the equivalent material properties method and the sequential coupling method, this paper studies the mechanical properties of a 3 MJ toroidal SMES magnet wound by a composite HTS conductor. Based on the electromagnetic-structural coupling analysis, the Von-Mises stress, the radial stress, and the hoop stress of a magnet coil are calculated and employed to validate the stability of the MJ-class toroidal SMES magnet. Index Terms-SMES, composite HTS conductor, equivalent material properties, sequential coupling, mechanical analysis I. INTRODUCTION UPERCONDUCTING Magnetic Energy Storage (SMES) systems have the advantages of high power density and a fast response speed. They can be used to compensate voltage sags and mitigate power fluctuations in an electrical grid [1]. SMES technology can also be used to facilitate the gridconnection of renewable energy, increase the stability of a power grid and the quality of power supply [2]. In the near future, an MJ-class SMES system is expected to play an important role in power grids. An MJ-class SMES system carries large currents and creates a high field in operation. An SMES magnet is considered to be a key component of the SEMS system. If an SMES magnet were wound by a commercial superconductor, such as a YBCO tape with the cross-section of 4.4 mm×0.1 mm, whose critical current is limited to 100 A~300 A (@77 K, self-field), it would be very difficult to achieve large-capacity energy storage higher than the MJ-class considering the expensive cooling cost. Consequently, it would not provide a favorable condition for the applications of MJ-class SMES systems in power grids. Compared with a parallel stacked wire, a composite HTS
Three dimensional (3D) models provide insights into the distribution, external and internal geometry of the reservoirs. The core description shows that the fourth segment of Funing Formation (E1f4), Oubei Block, Jinhu Depression mainly develop delta front subfacies which included underwater distributary channel, mouth bar, sand sheet and so on. Well data and structural maps were integrated to build 3D structure model and sedimentary microfacies model of Oubei reservoirs using stochastic simulations with geometry data. The result of facies-controlled property model can reasonably reflect reservoir characteristics in detail, providing a reliable geological model for late reservoir adjustment and valuable reference for numerical reservoir simulation as well.
In view of that detent force (DF) spatial harmonic has great influence on thrust ripple of permanent magnet synchronous linear motor (PMSLM), a harmonic suppression method is proposed. DF of the PMSLM model is calculated by finite element method (FEM) and its harmonic spectrum is achieved by Fourier transform (FT). Also total harmonic distortion (THD) is introduced to quantificat spatial harmonic. The effects of air gap, permanent magnet (PM) size, primary size, secondary size and pole-arc coefficient upon DF are analyzed. In order to minimize THD, orthogonal optimization design is adopted to optimize PMSLM structural parameters. A double-secondary PMSLM is chosen as the subject of research in the paper. Based on quantitative calculation, orthogonal experiment and range analysis are used to obtain optimal structures. This paper provides an effective quantitative analysis method for PMSLM spatial harmonic suppression.
The phase equilibrium of the quaternary system H2O-H2O2-CO(NH2)2-C3H8 with gas hydrate formation had been studied at high pressure and low temperature. The temperature and pressure of gas hydrate formed from different hydrogen peroxide concentration aqueous were determined at adding surfactants and no surfactants separately. It was concluded that the equilibrium pressure of gas hydrate formation was increasing with the increase of the hydrogen peroxide concentration, the urea concentration and the temperature, the mother liquor amount entrained in the gas hydrate after liquid separation by sinking was very high when surfactants was not added, but the equilibrium pressure of gas hydrate formation was decreased and the mother liquor amount entrained in gas hydrate was also decreased when surfactants was added to the system. In addition, the equilibrium pressure of gas hydrate formation in the quaternary system H2O-H2O2-CO(NH2)2-C3H8 was calculated according to Chen-Guo thermodynamic model, improved UNIFAC mathematical equation and Aasberg-Peterson fugacity coefficient model. The calculated data was in agreement with the experiment data.
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