Other

Centre National De La Recherche Scientifique

Commissariat a L'energie Atomique Et Aux Energies Alternatives

Institut Polytechnique De Grenoble

Ge Renewable Technologies

Alstom Renewable Technologies

Centre National De La Recherche Scientifique-Cnrs

Nicolas Perrissin-Fabert

Renaud Guillaume

Quentin Alloin

Bernard Dieny

Ricardo Sousa

Lucian Prejbeanu

Guillaume Renaud

A method for stabilizing the rotation speed of a machine with S-characteristics is provided. The method includes calculating a target net head and a target opening to affect guide vanes of the machine, the target net head and the target opening being calculated so that the torque exerted by water flow on the turbine is null and that the machine rotates at a target rotation speed; determining a real net head to which the machine is subjected; comparing the target net head with the real net head; and adjusting the opening of the guide vanes so as to converge towards the target opening and reduce a height difference between the target net head and the real net head.

Method for stabilizing the rotation speed of a hydraulic machine with S-characteristics and installation for converting hydraulic energy into electrical energy

A magnetic tunnel junction with out-of-plane magnetisation includes a storage layer; a reference layer; a tunnel barrier layer, the two magnetisation states of the storage layer being separated by an energy barrier, the magnetic tunnel junction having a thermal stability factor dependent on the energy barrier and on the temperature of use of the magnetic tunnel junction. The storage layer has a thickness comprised between 0.5 times and 8 times a characteristic dimension of a planar section of the tunnel junction; the composition and the thickness of the storage layer are chosen such that the absolute value of the derivative of the thermal stability factor compared to a characteristic dimension of a planar section of the tunnel junction is less than 10 nm.

Magnetic tunnel junction with perpendicular shape anisotropy and minimised variability, memory point and logic element including the magnetic tunnel junction, method for manufacturing the magnetic tunnel junction

A magnetic tunnel junction with out-of-plane magnetisation includes a storage layer; a reference layer; and a tunnel barrier layer. The two magnetisation states of the storage layer are separated by an energy barrier including a contribution due to the shape anisotropy of the storage layer and a contribution of interfacial origin for each interface of the storage layer. The storage layer has a thickness comprised between 0.8 and 8 times a characteristic dimension of a planar section of the tunnel junction. The contribution to the energy barrier due to the shape anisotropy of the storage layer is at least two times greater and preferably at least 4 times greater than the contributions to the energy barrier of interfacial origin.

Magnetic tunnel junction with perpendicular shape anisotropy and minimised variation of temperature memory point and logic element including the magnetic tunnel junction, method of manufacturing the magnetic tunnel junction

This method allows determining the operating point of a hydraulic machine in a considered operating range, such as turbine mode, and comprises steps that consist in a) determining two coordinates (N', T&#x2032;) of a first series of potential operating points of the hydraulic machine for the orientation affected to guide vanes of the machine, b) measuring the rotation speed of the machine, and c) determining the torque exerted by water flow on the machine. The method further includes steps consisting in d) calculating two coordinates (N, T) of a second series of potential operating points of the machine in function of the rotation speed (N) measured at step b) and the torque determined at step c), and e) deducing the two coordinates (N_real, T_real) of operating point that belongs both to the first and the second series in the said considered operating range of the machine.

Method for determining the operating point of a hydraulic machine and installation for converting hydraulic energy

The method allows stabilizing the rotation speed of a hydraulic machine with S-characteristics. It is implemented by means of a control loop feedback system having a controller for calculating an orientation to affect guide vanes of the machine. It includes steps of calculating a set of internal states associated with the operating point of the machine, establishing a linearized transfer function in function of the set of internal states, calculating characteristics parameters of the controller in function of the established transfer function so that the control loop feedback system is stable, measuring the rotation speed of the hydraulic machine, comparing the measured rotation speed with a target rotation speed, and adjusting the orientation affected to the guide vanes so as to reduce the speed difference between the calculated rotation speed and the target rotation speed.

Growing community of inventors

Grenoble, France

Nicolas Perrissin-Fabert