Topic
Inertia
About: Inertia is a research topic. Over the lifetime, 12006 publications have been published within this topic receiving 164291 citations.
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TL;DR: This paper presents how to improve the damping of the system by a derivative feedback of motor speed, and three kinds of typical pole assignments with identical radius/damping coefficient/real part are applied and compared.
Abstract: The purpose of this paper is to develop systematic analysis and design methods for a two-inertia system. A conventional proportional-integral speed control system with a torsional load is redesigned, and the damping characteristic of the system is derived and analyzed. It is shown that the dynamic characteristic of the system strongly depends on the inertia ratio of load to motor. Three kinds of typical pole assignments with identical radius/damping coefficient/real part are applied and compared, and the merits of each pole-assignment design are concluded. Furthermore, for small inertia ratio, we present how to improve the damping of the system by a derivative feedback of motor speed.
282 citations
TL;DR: In this paper, an improved active power control method for variable speed wind turbine to enhance the inertial response and damping capability during transient events is investigated, which shifts the turbine operating point from the maximum power point tracking (MPPT) curve to the virtual inertia control (VIC) curve according to the frequency deviation.
Abstract: This paper investigates an improved active power control method for variable speed wind turbine to enhance the inertial response and damping capability during transient events. The optimized power point tracking (OPPT) controller, which shifts the turbine operating point from the maximum power point tracking (MPPT) curve to the virtual inertia control (VIC) curves according to the frequency deviation, is proposed to release the “hidden” kinetic energy and provide dynamic frequency support to the grid. The effects of the VIC on power oscillation damping capability are theoretically evaluated. Compared to the conventional supplementary derivative regulator-based inertia control, the proposed control scheme can not only provide fast inertial response, but also increase the system damping capability during transient events. Thus, inertial response and power oscillation damping function can be obtained in a single controller by the proposed OPPT control. A prototype three-machine system containing two synchronous generators and a PMSG-based wind turbine with 31% of wind penetration is tested to validate the proposed control strategy on providing rapid inertial response and enhanced system damping.
282 citations
TL;DR: The inertia of particles is the basis of the present model of particle "dry deposition" from a turbulent fluid as mentioned in this paper, and the basic physical concepts of particle thermal motion as described by Einstein are extended to describe the particle motion in nonisotropic turbulence in terms of a “turbophoretic” velocity.
Abstract: The inertia of particles is the basis of the present model of particle “dry deposition” from a turbulent fluid. The basic physical concepts of particle thermal motion as described by Einstein are herein extended to describe the particle motion in nonisotropic turbulence in terms of a “turbophoretic” velocity. The particle transfer from the turbulent fluid to a collecting black surface is therefore described in terms of a differential motion describing the chain of “inertial flights” undergone by the particle under the gradient of turbulence velocity component in the direction of the collecting surface. This model of dry deposition shows satisfactory agreement with experimental values of particle deposition velocity as a function of particle size.
282 citations
TL;DR: In this paper, two beam elements that relax the assumptions of Euler-Bernoulli and Timoshenko beam theories are developed, which take into account the effect of rotary inertia, shear deformation and torsion, and yet they lead to a constant mass matrix.
Abstract: This part of these two companion papers demonstrates the computer implementation of the absolute nodal coordinate formulation for three-dimensional beam elements. Two beam elements that relax the assumptions of Euler-Bernoulli and Timoshenko beam theories are developed. These two elements take into account the effect of rotary inertia, shear deformation and torsion, and yet they lead to a constant mass matrix. As a consequence, the Coriolis and centrifugal forces are identically equal to zero. Both beam elements use the same interpolating polynomials and have the same number of nodal coordinates. However, one of the elements has two nodes, while the other has four nodes. The results obtained using the two elements are compared with the results obtained using existing incremental methods. Unlike existing large rotation vector formulations, the results of this paper show that no special numerical integration methods need to be used in order to satisfy the principle of work and energy when the absolute nodal coordinate formulation is used. These results show that this formulation can be used in manufacturing applications such as high speed forming and extrusion problems in which the element cross section dimensions significantly change.
279 citations
TL;DR: In this paper, a derivation of the equation governing the pressure in a thin, flat film of ideal gas under isothermal conditions, when the surfaces bounding the film are in relative normal and tangential motion, is presented.
Abstract: : A derivation is presented of the equation governing the pressure in a thin, flat film of ideal gas under isothermal conditions, when the surfaces bounding the film are in relative normal and tangential motion. When tangential motion is absent, the pressure equation reduces to a nonlinear heat equation, which admits of very few closed-form solutions. Various approximation methods are discussed, and two problems involving small periodic variation of the gap between parallel plates are solved by perturbation method for a film in which fluid inertia is negligible.
279 citations