Abstract: A system for extracting work from the expansion of a working fluid includes a vessel having at least a portion of the working fluid, a heating device in thermal communication with the portion of the working fluid in the vessel for heating the portion of the working fluid in the vessel and expanding the working fluid, and a conversion tool. The conversion tool is in fluid communication with the vessel and is configured to receive working fluid from the vessel when the working fluid expands. The conversion tool is further configured to extract work from the expanded working fluid.

Abstract: A power take-off apparatus for a wave energy converter of point absorber type, includes a cylinder attachable to a floating device, a piston that reciprocates inside the cylinder and has a piston rod attachable to a mooring, at least one penstock with a first end in communication with a second end of the cylinder through a first opening, and a second end having a second opening, and a housing above a cylinder first end. The housing communicates with the penstock through the second opening and with the cylinder through a third opening in the housing such that the cylinder, penstock and the housing form a closed loop for a fluid in the power take-off apparatus. A water turbine is arranged inside the housing so that working fluid entering the housing from the at least one penstock causes rotation of the water turbine to drive an electrical generator connected thereto.

Abstract: A detection system and method for rotor dynamic turn-to-turn short circuit fault of synchronous generator are disclosed. The system includes a motor, a synchronous generator, a current transformer, an acquisition card, an infrared temperature sensor, a temperature acquisition instrument and a control terminal. The rotor winding dynamic turn-to-turn short circuit fault of synchronous generator is detected and located by measuring the double judgment standards of the temperature signal of rotor winding and the three-phase current signal of stator winding. The method is easy to operate and has high sensitivity. The detection and location process of the fault is efficient and reliable. The dynamic turn-to-turn short circuit fault can be detected in the early stage of the formation of rotor static turn-to-turn short circuit, so as to reduce the loss of power plant fault shutdown and better meet the needs of practical application.

Abstract: The invention relates to a method for controlling a power generating unit such as a wind turbine which is configured as a virtual synchronous machine. Capacitor voltage signals obtained from voltage measurements of output capacitors are filtered in order to reduce a magnitude of an impedance peak and/or shift the impedance peak where the impedance peak is present in an impedance characteristic of the output of the power generating unit. Filter compensated voltage signals obtained from the output capacitors are combined with a voltage magnitude reference to obtain filtered capacitor voltage signals used for controlling the line side converter and thereby affect the impedance peak in a desired way.

Abstract: A method of operating at least one wind turbine including: receiving a first signal which is indicative of a level of a remuneration for electrical energy, which is fed currently and/or in the future into a grid to which the wind turbine is connected, producing a control signal dependent on the first signal, and controlling the wind turbine with the control signal for generating power of the wind turbine, that is dependent on the control signal. A wind turbine and a central control for carrying out such a method and a system comprising a central control and a plurality of wind turbines.

Abstract: A method for providing grid-forming control of an inverter-based resource connected to an electrical grid includes providing, via a processor, at least one virtual impedance value of the inverter-based resource. The method also includes determining a voltage drop across the at least one virtual impedance value of the inverter-based resource using at least one current feedback signal, the voltage drop comprising a voltage magnitude and a voltage angle. Further, the method includes receiving one or more voltage or current signals of the inverter-based resource. Moreover, the method includes determining a control command for the inverter-based resource as a function of the voltage drop across the virtual impedance value(s) of the inverter-based resource and the one or more voltage or current signals.

Abstract: A method for operating an asynchronous inverter-based resource connected to a power grid as a virtual synchronous machine to provide grid-forming control thereof includes receiving a frequency reference command and/or a voltage reference command. The method also includes determining at least one power reference signal for the inverter-based resource based on the frequency reference command and/or the voltage reference command. Further, the method includes generating at least one current vector using the power reference signal(s). Moreover, the method includes determining one or more voltage control commands for the inverter-based resource using the at least one current vector.

Abstract: The present application relates to a method for controlling a power system connected to a power grid, including: receiving a reactive power instruction and a measured reactive power from a generator; generating a reactive power error signal based on the difference between the reactive power instruction and the measured reactive power; receiving the reactive power error signal; generating a voltage instruction based on reactive power error signal; generating a voltage droop signal based on a reference reactance and a voltage at a point of common coupling; generating a voltage error signal according to at least one of the voltage instruction or the measured terminal voltage of the generator and the voltage droop signal; and producing a reactive current instruction for the converter power path based on the voltage error signal. The present application also discloses a control system for a power system connected to a power grid and a wind farm.

Abstract: Provided is an arrangement for controlling a converter of a power generation system, for example, a wind turbine, the converter being connected to a connection point to a utility grid, the arrangement including: a measurement section adapted to provide measurement values indicative of values of current and voltage at the connection point, a main converter controller adapted to receive the measurement values and to generate a main converter control signal based on the measurement values, an active filter system adapted to receive the measurement values and to generate an active filter control signal based on the measurement values, an addition element adapted to add the main converter control signal and the active filter control signal and to supply the sum signal as a control signal to the converter.

Abstract: The present application relates to a method for controlling a power system connected to a power grid, including: receiving a reactive power instruction and a measured reactive power from a generator; generating a reactive power error signal based on the difference between the reactive power instruction and the measured reactive power; receiving the reactive power error signal; generating a voltage instruction based on reactive power error signal; generating a voltage droop signal based on a reference reactance and a voltage at a point of common coupling; generating a voltage error signal according to at least one of the voltage instruction or the measured terminal voltage of the generator and the voltage droop signal; and producing a reactive current instruction for the converter power path based on the voltage error signal. The present application also discloses a control system for a power system connected to a power grid and a wind farm.

Abstract: A method for controlling a multiphase separately excited synchronous generator in a wind turbine is provided. The generator has a stator and an armature having an excitation input, connected to an excitation controller, for inputting an excitation current or an excitation voltage. The stator has a stator output, connected to a rectifier, for delivering stator currents. The rectifier is controllable to control the stator currents by detecting a speed of the armature or rotor, determining a setpoint power to be delivered by the generator or the turbine based on the speed, determining an excitation current or voltage based on the detected speed and determined setpoint power, inputting the excitation current or voltage by excitation controller at the excitation input, determining the stator currents as setpoint stator currents based on the speed and the setpoint power, and controlling the rectifier to set the stator currents to the setpoint stator currents.

Abstract: The disclosure relates to an active damping control method and system for sub-synchronous oscillation of DFIG, and storage medium. The method comprises the following steps: collecting oscillation components of stator current and/or stator voltage; determining each energy branch in DFIG converter according to the flow path of the oscillation component(s) of the stator current and/or the stator voltage in DFIG converter; determining the corresponding function of each energy branch according to oscillation component(s) the stator current and/or the stator voltage; determining the energy compensation branch and its corresponding energy compensation function in DFIG converter according to the corresponding function of each energy branch and converter parameters; controlling the sub-synchronous oscillation of DFIG by controlling the energy compensation branch according to the energy compensation function.

Abstract: A braking device for a movable door leaf according to the invention comprises at least one generator, at the output terminals of which, a generator voltage can be generated, by means of which a charging circuit for supplying an open-loop and/or closed-loop control unit may be charged, by means of which an electric braking device, such as, in particular, a braking motor or the like, is controllable, which generates an effective braking force for damping the movement of the door leafs. Therein, the generator shaft of the generator is rotatable for generating the generator voltage with the discharging of a mechanical generator energy storage specifically associated with the generator, which is charged by a respective opening or closing movement of the door, and, during a respective closing or opening movement of the door, is mechanically decoupled from the same or its axis of rotation, and discharges in the state mechanically decoupled from the door leaf or its axis of rotation.

Abstract: A compression pipe is configured with a wave drawing section and an air compressing section, a gas-liquid introduction on-off valve is disposed in wave drawing section, a gas-liquid introduction on-off valve is opened at an initial stage of a pushing wave, the gas-liquid introduction on-off valve is closed at the same time when a wave that maintains a speed flows into a wave receiving box. Accordingly, the wave is drawn into the air compressing section, is stored in a compressed air storage tank by converting kinetic energy of the wave into compressed air, and can be utilized for power generation and the like.

Abstract: An energy storage and delivery system includes an elevator operable to move blocks from a lower elevation to a higher elevation to store energy and from a higher elevation to a lower elevation to generate electricity. A winch assembly is movably coupled to a cable that is coupled to the elevator. The winch assembly has planetary gear assemblies, brakes that selectively engage at least a portion of the planetary gear assemblies, and a spool coupled to the cable. A drive shaft extends between a motor-generator and the winch assembly. A brake is operable so that the spool rotates to reel-in the cable to raise the elevator to move a block from a lower elevation to a higher elevation to store energy or so that the spool rotates to reel-out the cable to lower the elevator to move a block from a higher elevation to a lower elevation to generate electricity.

Abstract: A system and methods are provided for a wing stabilizer charging system for recharging onboard batteries during operation of an electrically powered vehicle. The wing stabilizer charging system comprises a wing stabilizer configured to be coupled with a rear of the vehicle. One or more air inlets are disposed in the wing stabilizer and configured to receive an airstream during forward motion of the vehicle. Wind turbines are disposed within the wing stabilizer and configured to be turned by the airstream. A circuit box is configured to combine electricity received from the wind turbines into a useable electric current. A power cable extends from the circuit box and is configured to supply the useable electric current to any one or more electronic devices, such as any of an onboard battery for powering the vehicle, mobile phones or smart phones, portable music players, tablet computers, cameras, and the like.

Abstract: Apparatus and associated methods relate to active damping of mechanical oscillations of a synchronous generator's drivetrain by modulating an excitation signal provided to the synchronous generator in proper phase relation with detected mechanical oscillations so as to dampen these oscillations. The excitation signal includes a superposition of a voltage-regulation signal and an active-damping signal. The voltage-regulation signal is configured to regulate an output voltage of electrical power provided by the synchronous generator, and the active-damping signal is configured to provide active damping to the drivetrain of the mechanical system that includes the synchronous generator. The active-damping signal is generated by detecting mechanical oscillations of the drivetrain, filter such detected mechanical oscillations such that the active-damping signal has a proper phase relationship with the mechanical oscillations over a predetermined range of frequencies.

Abstract: A method for preventing damage in a bearing of a generator includes monitoring, via a controller, one or more electrical signals of the power conversion assembly. The method also includes converting the electricals signal(s) to a frequency domain. Further, the method includes extracting one or more spectral components in frequency bands of the frequency domain around one or more known characteristic frequencies of the bearing. Moreover, the method includes determining at least one characteristic of the spectral component(s) in the frequency bands. In addition, the method includes comparing the characteristic(s) of the spectral component(s) in the frequency bands to at least one baseline value. The method further includes generating a fault signal or a baseline signal for the bearing based on the comparison. In response to the fault signal being generated, the method includes implementing a control action.

Abstract: An aquifer storage and recovery system can include a pump, an electric motor coupled to the pump, a drive unit configured to control operation of the electric motor, and a controller. The controller can be configured to flow water into a well bore from a source reservoir through the pump such that the pump rotates in a reverse direction and drives the electric motor coupled to the pump in the reverse direction to operate as a generator, determine a power output of the electric motor, determine a difference between the power output of the electric motor and a power output set point, and operate the drive unit to control a rotational speed of the electric motor based at least in part on the difference between the power output of the electric motor and the power output set point.

Abstract: The invention relates to a method for determining power set points of a power plant comprising a plurality of power generating units with at least one wind turbine generator. The determination of the power set points are based on a prioritization of the power generating units, where the power generating units are prioritized with respect to individual power levels or fatigue levels obtained for the power generating units. The prioritization is adjusted so that the adjusted prioritization depends both on the power and fatigue levels.