A method and device for determining a suction height of a variable speed unit is provided. The method includes: acquiring a reference cavitation coefficient and a reference specific rotation speed parameter corresponding to a target water head section in a preset number of power stations; conducting calculations on the reference cavitation coefficient and the reference specific rotation speed parameter by utilizing a target scheme to obtain a target formula; acquiring a maximum lift, a minimum lift, a speed variation range and a synchronous rotation speed value of a current target variable speed unit and input force values of the target variable speed unit at a plurality of key working condition points; and determining a target suction height of the target variable speed unit.

A method and device for determining a suction height of a variable speed unit is provided. The method includes: acquiring a reference cavitation coefficient and a reference specific rotation speed parameter corresponding to a target water head section in a preset number of power stations; conducting calculations on the reference cavitation coefficient and the reference specific rotation speed parameter by utilizing a target scheme to obtain a target formula; acquiring a maximum lift, a minimum lift, a speed variation range and a synchronous rotation speed value of a current target variable speed unit and input force values of the target variable speed unit at a plurality of key working condition points; and determining a target suction height of the target variable speed unit.

The invention relates to a system for energy storage and recovery, comprising: at least one compressed-air tank, at least one pressurized-water tank in communication with the compressed-air tank, at least one turbine in effective communication with the at least one pressurized-water tank, a generator for generating electrical energy, a high-pressure pump for pumping water from a water reservoir into the pressurized-water tank. According to one aspect of the invention, the turbine in effective communication with the at least one pressurized-water tank is a reaction turbine, which is connected in series with a constant pressure turbine in such a manner that a drive shaft of the reaction turbine is connected to a drive shaft of the constant pressure turbine and a drive shaft of the generator, and the constant pressure turbine is arranged between the reaction turbine and the generator, wherein the generator includes an interface for connection to a public power grid.

The invention relates to a system for energy storage and recovery, comprising: at least one compressed-air tank, at least one pressurized-water tank in communication with the compressed-air tank, at least one turbine in effective communication with the at least one pressurized-water tank, a generator for generating electrical energy, a high-pressure pump for pumping water from a water reservoir into the pressurized-water tank. According to one aspect of the invention, the turbine in effective communication with the at least one pressurized-water tank is a reaction turbine, which is connected in series with a constant pressure turbine in such a manner that a drive shaft of the reaction turbine is connected to a drive shaft of the constant pressure turbine and a drive shaft of the generator, and the constant pressure turbine is arranged between the reaction turbine and the generator, wherein the generator includes an interface for connection to a public power grid.

Disclosed herein is a novel method for operating a hydropower reservoir which is an improvement over the existing single-parameter (the current month) USACE Rule Curve approach, the improvement comprising the consideration of a second parameter, namely the water level of the reservoir at the beginning of the month, in the decision-making process for operation of the reservoir.

Disclosed herein is a novel method for operating a hydropower reservoir which is an improvement over the existing single-parameter (the current month) USACE Rule Curve approach, the improvement comprising the consideration of a second parameter, namely the water level of the reservoir at the beginning of the month, in the decision-making process for operation of the reservoir.

This invention relates to a submersible hydroelectric generator apparatus (1) and a method of evacuating water from such an apparatus. The method of evacuating water from a submersible hydroelectric generator apparatus (1) comprising the steps of pressurizing a fluid supply in the submersible hydroelectric generator apparatus using the water flowing into the apparatus and thereafter using the thus-pressurized fluid supply to evacuate the water from the apparatus. Additional pressurized fluid can be supplied to provide a pressurized fluid supply with sufficient pressure to expel the water from the apparatus. The apparatus (1) can be used in a grid connected electricity generating system or indeed in a smaller scale implementation such as in a single building or group of buildings to provide electricity to those buildings. The invention overcomes problems with prior art devices by evacuating water from the apparatus in an efficient manner.

This invention relates to a submersible hydroelectric generator apparatus (1) and a method of evacuating water from such an apparatus. The method of evacuating water from a submersible hydroelectric generator apparatus (1) comprising the steps of pressurizing a fluid supply in the submersible hydroelectric generator apparatus using the water flowing into the apparatus and thereafter using the thus-pressurized fluid supply to evacuate the water from the apparatus. Additional pressurized fluid can be supplied to provide a pressurized fluid supply with sufficient pressure to expel the water from the apparatus. The apparatus (1) can be used in a grid connected electricity generating system or indeed in a smaller scale implementation such as in a single building or group of buildings to provide electricity to those buildings. The invention overcomes problems with prior art devices by evacuating water from the apparatus in an efficient manner.

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 (N11, T11) 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.

A system for generating power from a flow of liquid having at most fifty feet of head and a flow rate of at most 300 cubic feet per second, includes: an axial-flow turbine, a penstock, an intake, a generator, and a control circuit. Each blade of the turbine runner is releasably coupled to the hub and each blade: 1) is configured to extract energy from liquid flowing through the runner by rotating the hub when the flow of liquid contacts the blade, and 2) has a pitch that is adjustable. The length of the penstock is adjustable. The generator is operable to generate electric power from rotation of the turbine. The control circuit to determines changes in the flow of liquid and in response modifies at least one of the following: 1) the speed of the axial-flow turbine's hub, and 2) the flow of liquid that the runner receives.