The Experts below are selected from a list of 6312 Experts worldwide ranked by ideXlab platform

M Hernandezgomez - One of the best experts on this subject based on the ideXlab platform.

  • Fixed Reference Frame phase locked loop for grid synchronization under unbalanced operation
    IEEE Transactions on Industrial Electronics, 2011
    Co-Authors: G Escobar, M F Martinezmontejano, A A Valdez, P R Martinez, M Hernandezgomez
    Abstract:

    This paper presents a grid synchronization scheme aimed to provide an estimation of the angular frequency and both the positive and negative sequences of the fundamental component of an unbalanced three-phase signal. These sequences are provided in Fixed-Reference-Frame coordinates, and thus, the proposed algorithm is referred to as Fixed-Reference-Frame phase-locked loop (PLL) (FRF-PLL). In fact, the FRF-PLL does not require transformation of variables into the synchronous Frame coordinates as in most PLL schemes. Therefore, the proposed scheme is not based on the phase angle detection. Instead, the angular frequency is detected and used for synchronization purposes. The design of the FRF-PLL is based on a complete description of the source voltage involving both positive and negative sequences in stationary coordinates and considering the angular frequency as an uncertain parameter. Therefore, the FRF-PLL is intended to perform properly under severe unbalanced conditions and to be robust against angular frequency variations, sags, and swells in the three-phase utility voltage signal. Due to the selective nature of the scheme, it shows certain capability to alleviate the effect of harmonic distortion that is present in the utility voltage signal.

Marta Folgueira - One of the best experts on this subject based on the ideXlab platform.

  • free polar motion of a triaxial and elastic body in hamiltonian formalism application to the earth and mars
    Astronomy and Astrophysics, 2005
    Co-Authors: Marta Folgueira, J Souchay
    Abstract:

    The purpose of this paper is to show how to solve in Hamiltonian formalism the equations of the polar motion of any arbitrarily shaped elastic celestial body, i.e. the motion of its rotation axis (or angular momentum) with respect to its figure axis. With this aim, we deduce from canonical equations related to the rotational Hamiltonian of the body, the analytical solution for its free polar motion which depends both on the elasticity and on its moments of inertia. In particular, we study the influence of the phase angle δ, responsible for the dissipation, on the damping of the polar motion. In order to validate our analytical equations, we show that, to first order, they are in complete agreement with those obtained from the classical Liouville equations. Then we adapt our calculations to the real data obtained from the polar motion of the Earth (polhody). For that purpose, we characterize precisely the differences in radius J − χ and in anglel − θ between the polar coordinates (χ, θ )a nd (J, l) representing respectively the motion of the axis of rotation of the Earth and the motion of its angular momentum axis, with respect to an Earth-Fixed Reference Frame, after showing the influence of the choice of the origin on these coordinates, and on the determination of the Chandler period as well. Then we show that the phase lag δ responsible for the damping for the selected time interval, between Feb. 1982 and Apr. 1990, might be of the order of δ ≈ 6 ◦ , according to a numerical integration starting from our analytical equations. Moreover, we emphasize the presence in our calculations for both χ and θ, of an oscillation with ap eriodTChandler/2, due to the triaxial shape of our planet, and generally not taken into account. In a last step, we apply our analytical formulation to the polar motion of Mars, thus showing the high dependence of its damping on the poorly known value of its Love number k. Moreover we emphasize the large oscillations of Mars' polar motion due to the triaxiality of this planet.

G Escobar - One of the best experts on this subject based on the ideXlab platform.

  • Fixed Reference Frame phase locked loop for grid synchronization under unbalanced operation
    IEEE Transactions on Industrial Electronics, 2011
    Co-Authors: G Escobar, M F Martinezmontejano, A A Valdez, P R Martinez, M Hernandezgomez
    Abstract:

    This paper presents a grid synchronization scheme aimed to provide an estimation of the angular frequency and both the positive and negative sequences of the fundamental component of an unbalanced three-phase signal. These sequences are provided in Fixed-Reference-Frame coordinates, and thus, the proposed algorithm is referred to as Fixed-Reference-Frame phase-locked loop (PLL) (FRF-PLL). In fact, the FRF-PLL does not require transformation of variables into the synchronous Frame coordinates as in most PLL schemes. Therefore, the proposed scheme is not based on the phase angle detection. Instead, the angular frequency is detected and used for synchronization purposes. The design of the FRF-PLL is based on a complete description of the source voltage involving both positive and negative sequences in stationary coordinates and considering the angular frequency as an uncertain parameter. Therefore, the FRF-PLL is intended to perform properly under severe unbalanced conditions and to be robust against angular frequency variations, sags, and swells in the three-phase utility voltage signal. Due to the selective nature of the scheme, it shows certain capability to alleviate the effect of harmonic distortion that is present in the utility voltage signal.

  • Fixed Reference Frame phase locked loop frf pll for unbalanced line voltage conditions
    Power Electronics Specialists Conference, 2008
    Co-Authors: M F Martinezmontejano, G Escobar, Raymundo E Torresolguin
    Abstract:

    In this work a phase-locked loop (PLL) is presented, which is able to provide an estimation of the angular frequency, and both the positive and negative sequences of the fundamental component of a three-phase signal. These sequences are provided in Fixed Reference Frame coordinates, and thus the proposed algorithm is referred as Fixed Reference Frame PLL (FRF-PLL). In fact, the FRF-PLL does not require transformation of variables into the synchronous Frame coordinates as in most PLL schemes. The design of the FRF-PLL is based on a complete description of the source voltage involving both positive and negative sequences in stationary coordinates and considering the angular frequency as an uncertain parameter. Therefore, the FRF-PLL is intended to perform properly under severe unbalanced conditions, and to be robust against angular frequency variations in the three-phase source voltage signal. Although not considered in the design, it is shown that the scheme is also robust against harmonic distortion present in the source voltage signal.

J Souchay - One of the best experts on this subject based on the ideXlab platform.

  • free polar motion of a triaxial and elastic body in hamiltonian formalism application to the earth and mars
    Astronomy and Astrophysics, 2005
    Co-Authors: Marta Folgueira, J Souchay
    Abstract:

    The purpose of this paper is to show how to solve in Hamiltonian formalism the equations of the polar motion of any arbitrarily shaped elastic celestial body, i.e. the motion of its rotation axis (or angular momentum) with respect to its figure axis. With this aim, we deduce from canonical equations related to the rotational Hamiltonian of the body, the analytical solution for its free polar motion which depends both on the elasticity and on its moments of inertia. In particular, we study the influence of the phase angle δ, responsible for the dissipation, on the damping of the polar motion. In order to validate our analytical equations, we show that, to first order, they are in complete agreement with those obtained from the classical Liouville equations. Then we adapt our calculations to the real data obtained from the polar motion of the Earth (polhody). For that purpose, we characterize precisely the differences in radius J − χ and in anglel − θ between the polar coordinates (χ, θ )a nd (J, l) representing respectively the motion of the axis of rotation of the Earth and the motion of its angular momentum axis, with respect to an Earth-Fixed Reference Frame, after showing the influence of the choice of the origin on these coordinates, and on the determination of the Chandler period as well. Then we show that the phase lag δ responsible for the damping for the selected time interval, between Feb. 1982 and Apr. 1990, might be of the order of δ ≈ 6 ◦ , according to a numerical integration starting from our analytical equations. Moreover, we emphasize the presence in our calculations for both χ and θ, of an oscillation with ap eriodTChandler/2, due to the triaxial shape of our planet, and generally not taken into account. In a last step, we apply our analytical formulation to the polar motion of Mars, thus showing the high dependence of its damping on the poorly known value of its Love number k. Moreover we emphasize the large oscillations of Mars' polar motion due to the triaxiality of this planet.

M F Martinezmontejano - One of the best experts on this subject based on the ideXlab platform.

  • Fixed Reference Frame phase locked loop for grid synchronization under unbalanced operation
    IEEE Transactions on Industrial Electronics, 2011
    Co-Authors: G Escobar, M F Martinezmontejano, A A Valdez, P R Martinez, M Hernandezgomez
    Abstract:

    This paper presents a grid synchronization scheme aimed to provide an estimation of the angular frequency and both the positive and negative sequences of the fundamental component of an unbalanced three-phase signal. These sequences are provided in Fixed-Reference-Frame coordinates, and thus, the proposed algorithm is referred to as Fixed-Reference-Frame phase-locked loop (PLL) (FRF-PLL). In fact, the FRF-PLL does not require transformation of variables into the synchronous Frame coordinates as in most PLL schemes. Therefore, the proposed scheme is not based on the phase angle detection. Instead, the angular frequency is detected and used for synchronization purposes. The design of the FRF-PLL is based on a complete description of the source voltage involving both positive and negative sequences in stationary coordinates and considering the angular frequency as an uncertain parameter. Therefore, the FRF-PLL is intended to perform properly under severe unbalanced conditions and to be robust against angular frequency variations, sags, and swells in the three-phase utility voltage signal. Due to the selective nature of the scheme, it shows certain capability to alleviate the effect of harmonic distortion that is present in the utility voltage signal.

  • Fixed Reference Frame phase locked loop frf pll for unbalanced line voltage conditions
    Power Electronics Specialists Conference, 2008
    Co-Authors: M F Martinezmontejano, G Escobar, Raymundo E Torresolguin
    Abstract:

    In this work a phase-locked loop (PLL) is presented, which is able to provide an estimation of the angular frequency, and both the positive and negative sequences of the fundamental component of a three-phase signal. These sequences are provided in Fixed Reference Frame coordinates, and thus the proposed algorithm is referred as Fixed Reference Frame PLL (FRF-PLL). In fact, the FRF-PLL does not require transformation of variables into the synchronous Frame coordinates as in most PLL schemes. The design of the FRF-PLL is based on a complete description of the source voltage involving both positive and negative sequences in stationary coordinates and considering the angular frequency as an uncertain parameter. Therefore, the FRF-PLL is intended to perform properly under severe unbalanced conditions, and to be robust against angular frequency variations in the three-phase source voltage signal. Although not considered in the design, it is shown that the scheme is also robust against harmonic distortion present in the source voltage signal.