565 results about "Induction generator" patented technology

A variable speed wind turbine is disclosed comprising a turbine rotor that drives a doubly-fed induction generator, a matrix converter which converts variable frequency output into constant frequency output, and a control unit and a protection circuit for the matrix converter. Power is circulated in the system allowing for sensorless detection of rotor position and better output ratios of power from the system.

A variable speed system for use in systems, such as, for example, wind turbines, is described. The system comprises a wound rotor induction generator, a torque controller and a proportional, integral derivative (PID) pitch controller. The torque controller controls generator torque using field oriented control, and the PID controller performs pitch regulation based on generator rotor speed.

A variable speed wind turbine is disclosed comprising a turbine rotor that drives a doubly-fed induction generator, a matrix converter which converts variable frequency output into constant frequency output, and a control unit and a protection circuit for the matrix converter. Power is circulated in the system allowing for sensorless detection of rotor position and better output ratios of power from the system.

Recovery of electric power from low-grade waste heat / solar energy, comprising a closed-cycle charged refrigerant loop. Pressurized refrigerant fluid is pumped at ambient temperature through a heat exchanger connected to a waste heat / solar source to extract heat energy during conversion to a high pressure gas. Heated / pressurized refrigerant gas is inlet into an expander to power an output shaft during the expansion of the fluid to a cooled gas at approximately 0 psig. Cooled gaseous refrigerant is condensed to a liquid at low pressure and ambient temperature, and recycled under pressure to the heat exchanger. The expander is a reverse-plumbed gas compressor; the pressurized, hot refrigerant gas is inlet at what is ordinarily its outlet, and the normal inlet becomes the expander end. The refrigerant gas mass flow pressure / temperature drop spins the expander shaft for direct mechanical power take-off, or coupling to a synchronous or inductive generator to produce electricity.

A variable speed wind turbine having a doubly fed induction generator (DFIG), includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine. Thus, the power converter is not directly connected to the grid avoiding the introduction of undesired harmonic distortion and achieving a better power quality fed into the utility grid. Moreover, the variable speed wind turbine includes a power control and a pitch regulation.

A controller (28) for a doubly fed induction generator (12,20) adjusts control signals to a rotor side converter (24) and line side converter (22) to adjust rotor current when a voltage transient on a utility grid (10) occurs, so that the doubly fed induction generator can ride through the transient. The controller can also turn off the transistors of the rotor side converter (24) to reduce rotor current and / or activate a crowbar (42) to reduce the voltage of the DC link (26) connecting the converters (22, 24) when significant voltage transients occur on the grid (10). This permits continued operation of the DFIG system without disconnecting from the grid.

A variable speed system for use in systems, such as, for example, wind turbines, is described. The system comprises a wound rotor induction generator, a torque controller and a proportional integral derivative (PID) pitch controller. The torque controller controls generator torque using field oriented control, and the PID controller performs pitch regulation based on generator rotor speed.

The present invention relates to an improved wind turbine, of the type which employs doubly fed induction generators (DFIG), and a wind park including the same, which permits the use of lighter weight turbines, with the ability to have greater energy capture, more precise control of asymmetrical phases and enhanced maintenance and support of the grid during fault conditions.

Various embodiments of linear electric generators and arrangements thereof are disclosed. One such generator includes a permanent magnetic array with magnets that are oriented such that like poles of the magnets are disposed adjacently to concentrate a magnetic field through a coil array. To enhance the magnetic field distribution, the magnets are affixed under a compressive strain due to repulsive forces resulting from proximity of the like poles. According to another aspect, a plurality of vibrational linear electric generators (VLEGs) can be arranged so that magnets of different VLEGs are oriented so that poles of opposite polarity are disposed adjacently to further enhance magnetic field concentration through coil arrays. In addition, a plurality of wave energy converters can be arranged in very close proximity, at most 8 times a height of a buoyant portion of the converters, to act as a seawall and thereby protect various structures from ocean waves.

A controller (28) for a doubly fed induction generator (12,20) adjusts control signals to a rotor side converter (24) and line side converter (22) to adjust rotor current when a voltage transient on a utility grid (10) occurs, so that the doubly fed induction generator can ride through the transient. The controller can also turn off the transistors of the rotor side converter (24) to reduce rotor current and / or activate a crowbar (42) to reduce the voltage of the DC link (26) connecting the converters (22, 24) when significant voltage transients occur on the grid (10). This permits continued operation of the DFIG system without disconnecting from the grid.

A protection system and a protection method are provided for protecting a double fed induction generator and a gearbox during a grid fault. The protection system includes a plurality of controlled impedance devices. Each of the controlled impedance devices is coupled between a respective phase of a stator winding of the double fed induction generator and a respective phase of a grid side converter. The protection system also includes a controller configured for coupling and decoupling impedance in one or more of the plurality of controlled impedance devices in response to changes in at least one of a utility grid voltage and a utility grid current.

The supercapacitor-based grid fault ride-through system provides a dynamic model of a wind generation system including a Voltage Source Converter (VSC), which functions as a Static Compensator (STATCOM). The power control capability of the STATCOM is extended by incorporating energy stored in a supercapacitor. The system implements a vector control technique based on the decoupling of real and reactive power. Simulation results show that a fixed speed induction generator is capable of withstanding a significant grid fault when aided by the supercapacitor-based grid fault ride-through system. Moreover, the induction generator regains its pre-fault status immediately after the fault is cleared.

An indoor or outdoor induction cook top with a heat management system is disclosed. The cook top controls heat generated by various components, including the electronic controller, mechanical controls, and the induction generators. The heat management system provides precise temperature control and an efficient way of removing heat from the cooktop. The cook top construction provides the ability to incorporate a smooth ceramic glass cook top and a number of induction hobs in multiple arrangements. The cook top also features a reduction in the number of components, the efficient removal of generated heat, the reduction of noise, an increase in performance and a barrier airflow director. Consequently, the cook top may be installed in a countertop without the need for venting above the counter.

The invention discloses a controller and method for simulating the active power frequency of a double-fed induction generator (DFIG) in combination with inertia and over speed. The controller comprises a frequency deviation detecting module, a blocking module, a regulating variable setting module, a time delay module and a speed protecting module which are connected in sequence, wherein a real-time grid frequency signal and a frequency setting value are respectively input in the frequency deviation detecting module to obtain the frequency deviation signal of the grid at that time; the frequency deviation signal enters the regulating variable setting module through the blocking module, and the regulating variable setting module obtains a speed regulating variable according to the frequency deviation signal; and the speed protecting module enables the DFIG unit to exit frequency modulation under an abnormal speed condition, and can put into the frequency modulation again after time delay for a period of time. The controller has the beneficial effects that large-scale double-fed wind power integration takes the place of a conventional synchronous generator to cause that the system inertia is reduced and thus the transient stability of system frequency is worsened, and the comprehensive frequency controller provided by the invention can effectively solve the problem.

A power plant extracts energy from a free flowing motive fluid by means of a turbine mounted on a gimbal. The shroud element of the fluid intake has external rudders, in conjunction with the gimbal mounting, enabling the enclosed turbine to instantaneously respond to changes in the direction of the free flowing motive fluid thus ensuring the face area of the intake is always physically orthogonal to the direction of the motive fluid streamlines. The shroud element may also be buoyant so as to optimally extract energy from an upper non-turbulent and higher velocity layer of the free flowing motive fluid. To function within an inherently unsteady source of energy, the preferred embodiment of the turbine is coupled to a DC generator which may further be coupled to a voltage and current regulating circuit which either charges a battery, performs electrolysis of water to produce hydrogen fuel, or is further coupled to a DC motor coupled to an AC generator. Alternatively an AC induction generator may be coupled to the turbine. Other mechanical, electrical, electronic, or electromechanical features may optionally be implemented to perform such tasks as adaptively locating the turbine in the maximum velocity flow, adapting internal vane and runner blade pitches for various flow rates and loads, keeping the intake free of obstructions, preventing loss of aquatic life, controlling and communicating the state of charge of the battery, or gauging and controlling the electrolysis process and communicating the fullness of the hydrogen gas output tanks.

A buoy includes a flotation device configured to float at surface of a body of water. A vibrational linear electric generator (VLEG) is configured to generate power from vibrational oscillations caused by waves using compressed repulsive magnetic fields focused by end magnetic field deflecting magnets. A power collection circuit, which includes a first battery, is configured to collect and store energy generated by the VLEG. One or more electronic components are powered by the vibrational linear electric generator.

A variable speed wind turbine having a doubly fed induction generator (DFIG), includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine. Thus, the power converter is not directly connected to the grid avoiding the introduction of undesired harmonic distortion and achieving a better power quality fed into the utility grid. Moreover, the variable speed wind turbine includes a power control and a pitch regulation.

A variable speed wind turbine having a doubly fed induction generator (DFIG) includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine which guarantees a stable voltage to the power converter. Thus, the power converter is not directly connected to the grid allowing the continuous operation of the system during a low voltage event in the grid.

Disclosed is a controller of a grid coupled type doubly-fed induction generator having a multi-level converter topology, which can control the doubly-fed induction generator having a high voltage specification and can perform a fault ride-through function, an anti-islanding function and a grid voltage synchronization function required for a dispersed power generation facility. The controller makes a H-bridge multi-level converter generate a three-phase voltage waveform resulted from the structure that single-phase converters each being composed of a 2-leg IGBT are stacked in a serial manner, and controls a rotor current so as to make the rotor coil of the doubly-fed induction generator in charge of a slip power only. The boost converter is composed of a 3-leg IGBT and a boost inductor generating a direct current voltage of its source required for the H-bridge multi-level converter.

A variable speed power generator system, includes a primary power induction generator (12), a secondary control induction (14), each of the induction generators having a rotor (22, 24) mounted so as to be rotated by a common shaft (16) of a variable speed prime mover (20), an inverter (50) connected to the stator (15) of the secondary control induction generator, a controller (30) connected to the inverter controls the output of the inverter, output of the primary induction generator is connected to the grid (51), controller provides output signal to the inverter based on selected inputs to the controller so that the output of the primary induction generator matches the active and reactive power requirements of the grid. An induction machine which includes a rotor having laminations and insulated cage bars, the bars being electrically isolated from on another as well as electrically insulated from the laminations.

A variable speed wind turbine having a doubly fed induction generator (DFIG) includes an exciter machine mechanically coupled to the DFIG and a power converter placed between a rotor of the DFIG and the exciter machine which guarantees a stable voltage to the power converter. Thus, the power converter is not directly connected to the grid allowing the continuous operation of the system during a low voltage event in the grid.

A method and system for dissipating energy in a direct current (dc) bus of a doubly-fed induction generator (DFIG) converter during a grid event is described. In one aspect, the method comprises monitoring operating conditions of an electrical system, the electrical system comprising at least a DFIG generator and a line side converter and a rotor side converter connected by a dc bus having a dynamic brake connected thereto; detecting an overvoltage on the dc bus or a condition indicative of an overvoltage on the dc link is detected, the overvoltage on the dc bus or condition indicative of the overvoltage caused by a grid event; and causing energy in the dc link to be dissipated using the dynamic brake.

The invention provides a method for controlling without-position sensor vector of a doubly-fed wind generator, wherein the control method adopts closed loop algorithm on the basis of a model reference self-adaptive module to indentify the rotor position and the rotary speed of a double fed wind induction generator. The control of the without-position sensor vector is possible, the cost of a generator system is lowered, and the anti-interference ability is improved. Simultaneously, the control method also adopts a method for improving voltage module observation flux linkages to observe a stator flux linkage under a stator static coordinate and a rotor flux linkage under a rotor static coordinate, the method can solve the problems that flux linkage phases which are obtained through observing the flux linkage through adopting a high pass filtering method are advanced and the amplitude is reduced, and the flux linkage which is corresponding with true value phases and amplitude is obtained.

Disclosed herein is an electric power converting device and power converting method for controlling doubly-fed induction generators, which provides a synchronous generator for generating auxiliary electric power independently of a doubly-fed induction generator so as to generate electricity even in a system power-free environment, a grid-side converter is composed of a three-phase four-wire converter so as to generate a balanced voltage even in an unbalanced load condition and automatically synchronize a stator voltage of a doubly-fed induction generator and a system voltage with each other.

This invention discloses a system and method to operate a doubly-fed induction generator (DFIG) as a grid-friendly virtual synchronous generator (VSG). It comprises a DFIG modeled as a virtual differential gear that links a rotor shaft driven by a prime mover, a virtual stator shaft coupled with a virtual synchronous generator G and a virtual slip shaft coupled with a virtual synchronous motor M, and a variable frequency drive that behaves as a virtual synchronous motor-generator set to regulate the speed of the virtual synchronous motor M so that the speed of the virtual stator shaft, i.e., the speed of the virtual synchronous generator G, is within a narrow band around the grid frequency even when the rotor shah: speed changes. As a result, a grid-connected DFIG can be controlled to behave like a virtual synchronous generator without using a PLL.

Disclosed herein is an electric power converting device and power converting method for controlling doubly-fed induction generators, which provides a synchronous generator for generating auxiliary electric power independently of a doubly-fed induction generator so as to generate electricity even in a system power-free environment, a grid-side converter is composed of a three-phase four-wire converter so as to generate a balanced voltage even in an unbalanced load condition and automatically synchronize a stator voltage of a doubly-fed induction generator and a system voltage with each other.

A power plant extracts energy from a free flowing motive fluid by means of a turbine mounted on a gimbal. The shroud element of the fluid intake has external rudders, in conjunction with the gimbal mounting, enabling the enclosed turbine to instantaneously respond to changes in the direction of the free flowing motive fluid thus ensuring the face area of the intake is always physically orthogonal to the direction of the motive fluid streamlines. The shroud element may also be buoyant so as to optimally extract energy from an upper non-turbulent and higher velocity layer of the free flowing motive fluid. To function within an inherently unsteady source of energy, the preferred embodiment of the turbine is coupled to a DC generator which may further be coupled to a voltage and current regulating circuit which either charges a battery, performs electrolysis of water to produce hydrogen fuel, or is further coupled to a DC motor coupled to an AC generator. Alternatively an AC induction generator may be coupled to the turbine. Other mechanical, electrical, electronic, or electromechanical features may optionally be implemented to perform such tasks as adaptively locating the turbine in the maximum velocity flow, adapting internal vane and runner blade pitches for various flow rates and loads, keeping the intake free of obstructions, preventing loss of aquatic life, controlling and communicating the state of charge of the battery, or gauging and controlling the electrolysis process and communicating the fullness of the hydrogen gas output tanks.

A protection system and a protection method are provided for protecting a double fed induction generator and a gearbox during a grid fault. The protection system includes a plurality of controlled impedance devices. Each of the controlled impedance devices is coupled between a respective phase of a stator winding of the double fed induction generator and a respective phase of a grid side converter. The protection system also includes a controller configured for coupling and decoupling impedance in one or more of the plurality of controlled impedance devices in response to changes in at least one of a utility grid voltage and a utility grid current.