A hydropower installation includes a water supply and an energy generating station, with the supply at a higher level than the energy generating station; and a duct extending between the supply and the energy generating station. The energy generating station of the hydropower installation is configured based on high water velocity and low pressure. The duct may comprise plastic pipes. The duct may be arranged on a foam support and enclosed by a foam embedment. The duct may comprise at least two duct sections, with an intermediate energy generating station arranged between the duct sections of the duct. The duct may comprise internally extending protrusions, such as dimples to promote a laminar flow of fluid through the pipe. The duct may taper. Water pressure inside the duct may be maintained at atmospheric level. The proposed features all contribute to a pressure free velocity based system.

A hydropower installation includes a water supply and an energy generating station, with the supply at a higher level than the energy generating station; and a duct extending between the supply and the energy generating station. The energy generating station of the hydropower installation is configured based on high water velocity and low pressure. The duct may comprise plastic pipes. The duct may be arranged on a foam support and enclosed by a foam embedment. The duct may comprise at least two duct sections, with an intermediate energy generating station arranged between the duct sections of the duct. The duct may comprise internally extending protrusions, such as dimples to promote a laminar flow of fluid through the pipe. The duct may taper. Water pressure inside the duct may be maintained at atmospheric level. The proposed features all contribute to a pressure free velocity based system.

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.

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.

A control device estimates a flow rate and an effective height difference of a fluid machine based on a characteristic detectable with regard to a rotating electrical machine and correlating with the flow rate and the effective height difference of the fluid machine. A total flow rate in a pipe system is estimated based on these values estimated by the control device and a flow resistance characteristic line, and cooperative control of the fluid machine and the flow rate control valve is performed such that the estimated value of the total flow rate becomes close to a target flow rate of the total flow rate in the pipe system.

A control device estimates a flow rate and an effective height difference of a fluid machine based on a characteristic detectable with regard to a rotating electrical machine and correlating with the flow rate and the effective height difference of the fluid machine. A total flow rate in a pipe system is estimated based on these values estimated by the control device and a flow resistance characteristic line, and cooperative control of the fluid machine and the flow rate control valve is performed such that the estimated value of the total flow rate becomes close to a target flow rate of the total flow rate in the pipe system.

A floating electrical power generator having a three-dimensional (3D) flow passageway configured for increasing the water flow on the paddle wheel to increase the power output.

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.

A hydroelectric power generation system includes a water turbine disposed in a channel that carries a flow of a fluid, a generator driven by the water turbine, and a controller that performs a first control. The channel includes a first channel located on an inflow side of the water turbine. The controller controls, in the first control, a flow rate or a head of the water turbine so that any one of a pressure of the fluid in the first channel, a flow rate of the fluid in the first channel, and a liquid level of the fluid in a first reservoir from which the fluid flows out to the first channel approaches a first target value.