Showing papers by "Vestas published in 1999"

Method of controlling the operation of a wind turbine and wind turbine for use in said method

Abstract: The wind turbine (1) comprises a rotor (2) with a number of blades mounted for rotation about a mainly horizontal axis, and the pitch of the blades of the wind turbine is controlled in dependence on measured parameters in order to optimize the operation of the wind turbine with respect to produced energy under varying weather and wind conditions. By measuring mechanical loads on the blades (7, 8), and controlling the pitch of the blades of the wind turbine in such a way, that the measured mechanical loads are maintained below certain limits during operation, the control can be performed closer to the mechanical load limits of the blades without risk of exceeding these limits.

Detector for high intensity electrical currents

Abstract: The invention discloses a detection- and recording system for high intensity electric currents such as lightning currents in a lightning conductor in a wind turbine. The system comprises a detector (6) containing a power supply (7), a measuring circuit (8), and a converter means (9) and furthermore a recording means (11) non-galvanically coupled to said converter means (9) and a measuring coil (5) to be inductively coupled to an electric conductor (2) carrying the high intensity electric current. The power supply (7) receives its electrical energy directly from the lightning current via the power coil (4) which makes the system non-sensitive to mains supply drop-outs.

Fibre-optical strain-gauge

Abstract: In a fiber-optical strain-gauge of the kind comprising a mechanical construction providing a linear, strain-dependent relative movement of oppositely positioned spaced-apart first and second optical fiber-holding elements in a direction substantially perpendicular to the axial direction of the optical fibers, and in which the varying transmission of light between the two fibers is used as an indication of the strain, the main new feature is that the strain-gauge is manufactured using the following steps: a) prestressing an optical fibre by applying a pulling force, or prestressing the mechanical construction by applying a compressing force; b) fixing said optical fiber to the fiber-holding elements in the mechanical construction; and c) cleaving the optical fiber at the interspace between the fiber-holding elements. With this arrangement the optical fiber ends are aligned in an exact position in a simple manner without using any expensive micro-manipulation tools, and a high precision of the gap between the two fiber ends can be provided in a simple manner by controlling the prestressing of the optical fiber, or the mechanical construction.

Method of manufacturing a fibre-optical strain-gauge and strain-gauge manufactured by said method

Abstract: In a fibre-optical strain-gauge of the kind comprising a mechanical construction providing a linear, strain-dependent relative movement of oppositely positioned spaced-apart first and second optical fibre-holding elements in a direction substantially perpendicular to the axial direction of the optical fibres, and in which the varying transmission of light between the two fibres is used as an indication of the strain, the main new feature is that the strain-gauge is manufactured using the following steps: a) prestressing an optical fibre by applying a pulling force, or prestressing the mechanical construction by applying a compressing force; b) fixing said optical fibre to the fibre-holding elements in the mechanical construction; and c) cleaving the optical fibre at the interspace between the fibre-holding elements. With this arrangement the optical fibre ends are aligned in an exact position in a simple manner without using any expensive micro-manipulation tools, and a high precision of the gap between the two fibre ends can be provided in a simple manner by controlling the prestressing of the optical fibre, or the mechanical construction.