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Abstract-This paper presents a voltage sag compensator, which uses a flywheel energy storage system with superconducting magnetic axial thrust bearing (SMB) and a permanent magnet radial bearing (PMB). The SMB was built with Nd-Fe-B magnet and YBCO superconducting blocks, refrigerated with liquid Nitrogen. The magnets are assembled with magnetic flux shapers in order to increase the levitation force and the stiffness. The radial PMB is used to positioning the vertically arranged switched reluctance machine (SRM) used as motor/generator. Simulations of the power electronics and SRM show that the system can work up to 30,000 rpm supplying the required energy during disturbances.

We analyze the thermodynamics of a black hole in a region that contains a global monopole in the framework of a particular class of a f (R) gravity. Specifically, we study the case in which df (R) dR = F (R) is a power law function of the radial coordinate of the monopole spacetime, i.e., F (r) = 1 + ψ n r n , where ψ n is the fine-tuned parameter corresponding to the f (R) gravity. We obtain explicit expressions for the local thermodynamic quantities of the black hole as a function of the event horizon, the parameter describing the monopole and the measurable corrections due to the f (R) theory modifications of the General Relativity. We also discussed the implications of the particular case of n = 2, where the parameter ψ 2 can be related to a positive cosmological constant, that in monopole presence is characterized by a non-trivial topology observed as a deficit solid angle.

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This paper presents test results of a flywheel energy storage system (FESS) prototype. The bearing system is composed of a superconducting magnetic thrust bearing (SMB) and a permanent magnet bearing (PMB). The SMB was built with Nd-Fe-B magnet and YBCO superconducting blocks. The PMB has the function of positioning radially the switched reluctance machine (SRM) used as motor/generator and reduce the load over the SMB. The SRM drive is responsible to convert electrical into mechanical energy, and vice versa. The prototype still operates at low speeds, but the dynamical simulations of the SRM drive showed that the system can work at high speed, supplying the required energy during disturbances. In the tests performed with the FESS prototype, the system took or delivered energy from/to the grid when requested.