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.

An apparatus is provided for modifying the geometry of at least one part of a turbine, which can include a shell assembly that includes an outer shell that is shaped to modify the shape of a pre-existing element of a turbine. The outer shell of the shell assembly can be composed of a fiber-reinforced polymeric material and can at least partially define an inner cavity. The outer shell can be bonded to a structure to modify the geometrical shape of that structure. Thereafter, a polymer casting can be injected into the inner cavity via at least one injection port attached to the shell assembly. In some embodiments, one or more stiffeners and/or a core can be positioned within the inner cavity to help improve the bonding of the polymer casting to the shell and/or improve a structural property of the apparatus.

A system for generating power from turbine arrays comprises a plurality of turbines positioned in a turbine array. Each turbine comprises a vertical shaft having an upper portion, a middle portion and a lower portion. The lower portion of the shaft is attached to a base member housing at a top portion thereof utilizing a lower shaft bearing. Thus, the shaft is configured to rotate and move linearly in an axial direction. Each turbine further comprises a turbine head having blades mounted at the upper portion of the shaft utilizing an upper shaft bearing and a first pulley coupled with a gear connected to the middle portion of the shaft. The system further comprises a generator having a second pulley that is engaged with the first pulley utilizing a coupling means. When the shaft rotates, the first and second pulleys turn to actuate the generator thereby generating electrical current.

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′11, T′11) 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 (N11, T11) 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 (N11_real, T11_real) of operating point that belongs both to the first and the second series in the said considered operating range of the machine.

The invention concerns a method for coupling to the grid a hydraulic unit having a synchronous generator, a runner, and wicket gates. The method includes a step of increasing the flow of water into the runner from a time t.sub.0 to a time t.sub.1 so that the rotation frequency of the rotor of the synchronous generator is, at time t.sub.1 equal to the frequency of the grid, and closing the circuit breaker at time t.sub.1. A sub-interval from a time t2 to time t1 is defined, with t0<=t2<t3<=t1, wherein a sub-step is executed to apply an adjustment torque to the shaft line via a first actuator that controls the flow of water into the runner and a second actuator coupled to a stator of the synchronous generator.

A startup method of a Francis turbine according to an embodiment includes: a first rotation-speed increasing step in which a rotation speed of the runner is increased by opening the guide vane at a first opening; a second rotation-speed increasing step in which the increase in the rotation speed of the runner is accelerated by opening the guide vane at a second opening that is larger than the first opening after the first rotation-speed increasing step; and a rotation-speed regulating step in which the rotation speed of the runner is regulated to a rated rotation speed by opening the guide vane at a no-load opening after the second rotation-speed increasing step. The first opening is an opening that is half or less than the no-load opening.

A startup method of a Francis turbine according to an embodiment includes: a bypass-valve opening step of opening the bypass valve with the inlet valve closed; an inlet-valve opening step of opening the inlet valve after the bypass-valve opening step; and a first rotation-speed increasing step of increasing a rotation speed of the runner by opening the guide vane at an opening that is 50% or more of a maximum opening before a flow velocity of a swirling flow flowing around the runner reaches 90 m/sec.

The disclosed hydroelectric power generation system includes a waterwheel rotated by falling water having multiple curved portions. Multiple circular members each having a cover are loaded in a corresponding one of the multiple curved portions, elevated with the cover in an open position to empty the circular member, filled with water upon reaching a top dead point thereof, and allowed to fall freely with the cover in a closed position. The cover of the circular members are automatically opened and closed. A track extends downwardly from a point at which the curved portion of the waterwheel is turned into a downwardly inclined position. The track guides the circular member to move by gravity along the track. A feed track allows the circular members to be supplied back to respective curved portions during rotation of the waterwheel. An output shaft of a gear train drives a generator.

According to the embodiment, in a range from a plane P1 including a runner rotation center axis C and an end point 15E2 of an outlet end 15 of the vane 13, up to a plane P2 corresponding to a position where the plane P1 is moved by an angle, which is determined by dividing 360° by a value that is four times the number of vanes 13, in a runner rotation direction, when respective sections of the vane 13 are taken at a plane including the axis C and radially extending, in at least one section, a tangent T1 on a centerline Cv of the vane 13 passing through an intersection X at which the centerline Cv and a flowing water surface 12f intersect, and a tangent T2 on the flowing water surface 12f passing through the intersection X, define an acute angle on a negative pressure surface.

A turbine assembly for a generator including a rotor that is operable to rotate about an axis; and a thrust absorbing member, wherein fluid is operable to enter the turbine assembly generally axially with regard to the axis of rotation of the rotor and to exit the turbine generally radially with regard to the axis of rotation of the rotor. The fluid is operable to contact the thrust absorbing member prior to contacting the rotor.