58 results about "Doubly fed machine" patented technology

Because of the necessity of resolver for detecting a rotating position, which is very expensive, and noise suppression of the rotating position signal line on a doubly-fed machine, cost increase of the generator and reduced reliability due to possible failures are inevitable. In order to solve such problem, a generation system in the present invention is equipped with an exciter that estimates the slip frequency of the doubly-fed machine from each primary current I1 and voltage V1 and secondary current I2 and voltage V2 of the doubly-fed machine and excites the secondary of the doubly-fed machine at the estimated slip frequency.

Because of the necessity of resolver for detecting a rotating position, which is very expensive, and noise suppression of the rotating position signal line on a doubly-fed machine, cost increase of the generator and reduced reliability due to possible failures are inevitable. In order to solve such problem, a generation system in the present invention is equipped with an exciter that estimates the slip frequency of the doubly-fed machine from each primary current I1 and voltage V1 and secondary current I2 and voltage V2 of the doubly-fed machine and excites the secondary of the doubly-fed machine at the estimated slip frequency.

The invention discloses a ship shaft generator system and a control method thereof, so as to solve the problems that seamless switching between power generation voltage and a frequency of brushless doubly-fed machine stator and voltage and frequency of a ship power station can not be realized in the prior art and the system can not operate stably when the ship load changes suddenly. The system mainly comprises a grid-connected device (11), an input filter unit (12), a grid-side power unit (13), a machine-side power unit (14), an output reactor (15) and a control system (17), wherein the grid-connected device is connected with the grid-side power unit via the input filter unit; the machine-side power unit is connected with a control winding (3) via the output reactor; and the grid-side power unit and the machine-side power unit are in back-to-back connection. An industrial PC (18) acquires current, voltage, rotation speed and busbar voltage of the brushless doubly-fed machine respectively and the ship shaft generator system is stably controlled. The control method of the invention adopts vector control algorithm and can be used in the ship shaft generator system.

The invention discloses a method and a system for detecting open phase. The method comprises the following steps: 1, according to acquired three phases of voltage values or current values Sa, Sb and Sc, the average three-phase value Savg and the maximum value Smax are calculated in real time; 2, filtering processing is carried out on the Smax and the Savg respectively, and an Smaxf1 and an Savgf1 are obtained; 3, conversion values Smaxf and Savgf for the Smaxf1 and the Savgf1 are calculated; 4, a voltage open phase detection judgment coefficient Kx is calculated; and 5, open phase judgment is carried out based on the Kx, if the Kx is larger than an open phase fault threshold Ks, happening of the open phase is judged, or otherwise, no open phase fault exists, and Ks is between 10% to 20%. The method is easy to implement, the calculation amount is small, and the method of the invention is a general defect detection method and is particularly applied to real-time open phase protection on a brushless doubly-fed machine.

The invention provides an indirect torque control method for a cage-rotor brushless doubly-fed machine (BDFM). In the method, particularly a computing method of a magnetic linkage variable angle deltaX of a control winding comprises the following steps: firstly obtaining the frequency of the control winding based on a rotating speed; calculating a static angle deltaXst based on the frequency of the control winding; and obtaining a dynamic angle deltaXd through a PI torque regulator, wherein, the sum of the obtained two angles is the magnetic linkage variable angle deltaX of the control winding within next sampling period Tpwm (trapezoidal pulse width modulation). The indirect torque control method solves problems such as great current harmonic wave of the control winding and great torque ripple in the case of low frequency in the direct torque control method for the BDFM; and the control system only requires resistance of two stator windings and has the advantages of fewer machine parameters, no need of rotational coordinate transformation, capability of realizing control of electromagnetic torque and magnetic linkage of the cage-rotor BDFM under a static coordinate system, simple control method and obvious effect.

The invention discloses a high-power brushless double-fed motor three-level bidirectional frequency conversion speed regulation system, which is characterized in that the system is composed of a brushless double-fed motor and a three-level dual PWM AC speed regulation system. The dual-PWM AC speed regulation system includes a brushless doubly-fed motor three-level PWM rectifier unit and a brushless doubly-fed motor three-level inverter unit. In the main circuit structure of the three-level dual-PWM AC speed regulation system of the present invention, four power devices are connected in series for each phase bridge arm. The three-level PWM rectifier can realize two-way flow of energy, improve energy recovery rate, and reduce energy loss of motor AC speed control system. It is suitable for high-voltage and high-power motor drive occasions.

A method for operating a doubly-fed machine by determining its rotational speed (nact), forming a rotational speed reference (nref), measuring network voltage and current, and calculating network active power (Pact) and reactive power (Qact). Thereafter, calculating shaft torque (T) based on active power (Pact) and rotating speed (nact), forming a frequency reference (Fref) for the inverter based on machine rotating speed (nact), rotating speed reference (nref), shaft torque (T), and the known pole pair number and network frequency, forming a reactive power reference (Qref) for the machine. Forming an Ir compensation reference (IRref) for the inverter on the basis of the reactive reference (Qref) and the reactive power (Qact), and controlling the inverter to produce rotor voltage based on frequency reference (Fref) and the IR compensation reference

The invention discloses a starting device of a brushless doubly-fed machine, and relates to the technical field of brushless doubly-fed machines. The direct-current output of a frequency converter is disconnected, and then switch tubes VT1, VT3, VT5 of an upper bridge arm and switch tubes VT2, VT4, VT6 of a lower bridge arm of a three-phase full bridge inversion circuit VI are disconnected at the same time, so that a brake resistor R0 is connected to a control winding PC, resources of the frequency converter can be sufficiently utilized, namely a starting resistor does not need to be used, the control winding PC can be in short connection by controlling full-controlled switch tube devices of the inversion circuit through software, the volume of the equipment can be reduced, and the cost is reduced.

Brushless doubly-fed machine (BDFM) is expected to be widely used in wind power generation due to its characteristics of doubly-fed machine without brush and slip ring. Doubly-fed wind turbine has a great influence on the system stability when it is connected to the grid through the power electronic interface, especially in the grid with high wind power permeability. If the wind turbine generatorsystem can have the friendly characteristics of traditional energy, it will greatly improve the stability of the system. Therefore, the invention provides a virtual synchronous control method for a brushless doubly-fed machine based on the control principle of the virtual synchronous generator, which simulates the operation characteristics of the synchronous generator. The phase angle and currentof the winding are controlled by active and reactive power respectively, and the operation characteristics of the synchronous motor are simulated. The inertia characteristics, frequency response characteristics and voltage regulation characteristics of synchronous generator set are simulated effectively by the control system.

A method for operating a doubly-fed machine by determining its rotational speed (nact), forming a rotational speed reference (nref), measuring network voltage and current, and calculating network active power (Pact) and reactive power (Qact). Thereafter, calculating shaft torque (T) based on active power (Pact) and rotating speed (nact), forming a frequency reference (Fref) for the inverter based on machine rotating speed (nact), rotating speed reference (nref), shaft torque (T), and the known pole pair number and network frequency, forming a reactive power reference (Qref) for the machine. Forming an Ir compensation reference (IRref) for the inverter on the basis of the reactive reference (Qref) and the reactive power (Qact), and controlling the inverter to produce rotor voltage based on frequency reference (Fref) and the IR compensation reference

The invention discloses an excitation control method of an independent generating system of a brushless doubly-fed machine under an asymmetric load. On the basis of positive-sequence and negative-sequence dual dq coordinate systems, a power winding (PW) voltage of a brushless doubly-fed machine is decomposed into a positive-sequence component and a negative-sequence component; a PW voltage positive-sequence component controller and a PW voltage negative-sequence component controller are used for adjusting amplitudes and frequencies of the PW voltage positive-sequence component and the PW voltage negative-sequence component so as to obtain a needed control winding (CW) voltage positive-sequence component and a needed CW voltage negative-sequence component; the CW voltage positive-sequence component and the CW voltage negative-sequence component are added to obtain a final CW voltage given value; according to the given value, a PWM modulation signal and thus an inverter is driven to control the CW; and then the amplitude and frequency of the PW voltage positive-sequence component track the given value respectively and the PW voltage negative-sequence component amplitude converges to zero. With the method, the constant-frequency and constant-voltage generating function of the independent generating system of the brushless doubly-fed machine under the asymmetric load can be realized. Moreover, the control method has advantages of simpleness, high reliability and high robustness.

Because of the necessity of resolver for detecting a rotating position, which is very expensive, and noise suppression of the rotating position signal line on a doubly-fed machine, cost increase of the generator and reduced reliability due to possible failures are inevitable. In order to solve such problem, a generation system in the present invention is equipped with an exciter that estimates the slip frequency of the doubly-fed machine from each primary current I1 and voltage V1 and secondary current I2 and voltage V2 of the doubly-fed machine and excites the secondary of the doubly-fed machine at the estimated slip frequency.

The invention relates to an initial position angle detecting device of a double-feed motor rotor and a method thereof. The device includes voltage detecting circuits that are respectively connected with a stator and a rotor of the doubly-fed machine. The voltage detecting circuits are respectively used for detecting the induced electromotive force which is output by the stator side and the rotor side of the double-feed motor, and converting the induced electromotive force into weak electrical signals. The voltage detecting circuits are respectively connected with zero crossing comparison circuits which convert the detected induced electromotive force output by the stator and the rotor of the voltage detecting circuits into square wave signals; the output ends of the zero crossing comparison circuits are respectively connected with two groups of photoelectric isolation circuits which deliver the square wave signals output by the zero crossing comparison circuits into a main processor circuit that processes data. The device is not only applicable to double-feed motors with small capacity but also to large-capacity fans and double-feed speed adjusting systems of pumps and the like. The structure of the device is simple and reliable, regardless of the connection way of the stator winding and the rotor winding. The device is characterized by the convenient use and easy operation, high test precision and wide application scope.

The invention provides a virtual impedance access method and device based on a short-circuit ratio and electronic equipment. A doubly-fed unit output impedance model comprises a rotor side impedance relation model, a short-circuit ratio and stator side drop voltage relation model and a short-circuit ratio and line impedance relation model under the condition of a weak power grid. Whether there is short-circuit fault misjudgment caused by voltage fluctuation variation or not is judged according to a preset condition; if it is judged that there is a short-circuit fault, the fault short-circuit current is calculated according to the rotor side impedance relation model, the short-circuit ratio and stator side drop voltage relation model and the short-circuit ratio and line impedance relation model; and a target virtual impedance access value is determined according to the fault short-circuit current and a preset maximum allowable current. Under the condition of a weak power grid, the optimal virtual impedance access value of a doubly-fed unit in the case of a power grid fault can be calculated in a short-circuit ratio optimal impedance calculation mode, so that the doubly-fed unit achieves the optimal fault ride-through capability.

The invention provides a harmonic staring type wound brushless doubly-fed machine. According to different conduction paths of rotor windings in different magnetic fields, rotor resistance is increased, and leakage reactance is not increased along with increasing of the rotor resistance, it is equivalent to equivalent access of added resistance, and a motor has the good starting performance; during normal operation, by means of change of rotor or stator winding connection, the non-inductive property disappears and is changed into the inductive property, the rotor resistance returns to normal, and it is equivalent to added resistance removal; the machine has the high operation efficiency, and then the wound induction machine can get rid of added starting resistance; the idea of getting rid of a slip ring and a brush is achieved, and the wide industrial application prospect is achieved.

The invention discloses a brushless doubly-fed machine hybrid cage type rotor structure and a winding method. The rotor core comprises a plurality of rotor nests evenly distributed along the circumference of the core, each rotor nest is constituted by a plurality of loops, the plurality of loops of each rotor nest are arranged from the inside to the outside, and at least two parallel coil groups are arranged in each rotor nest, and the coil groups are separated from each other and have no electrical connection; and at least one coil group is a series combination formed by the serial connection and self-closing of two or more adjacent loops. The cage type rotor can improve the operating efficiency and power factor or other operation performances of a BDFM prototype, the whole rotor is balanced in current distribution, the rotor magnetic potential tends to sinusoidal distribution, and the harmonic content is low.

The invention discloses a coolant-based brushless doubly fed machine cooling structure. A cooler is mounted at the top part of a casing; a sealing cover passes through a stator core bore, extends to the inner part of the cooler, and is isolated from rotor core space in the casing to form closing space; a coolant is injected in the sealing cover; a vent pipe is located at the axial outer side of the stator core; a plurality of sub plates are connected between a rotation shaft and the rotor core, and space between the sub plates forms a core axial air duct; an air gap is formed between the rotorcore and the inner circumferential surface of the sealing cover; an inner fan is fixed at a shaft extension end of the rotation shaft for generating a power airflow in a rotor circulation air path formed by the rotor core space, the vent pipe, the core axial air duct, a rotor core radial air duct and the air gap. In combination of the design of the brushless doubly fed machine core and a winding,a set of stator independent cooling loop and a set of rotor independent cooling loop are adopted, a complex cooling structure is reduced while the motor operation efficiency is improved, the use efficiency of the coolant is increased, the cost is reduced, and the reliability is improved.

The invention relates to a voltage source type wind turbine generator frequency modulation and voltage regulation control system and method. The system comprises a wind turbine generator and a flywheel energy storage unit, the flywheel energy storage unit comprises a flywheel, a motor and a motor frequency converter which are connected in sequence, and a wind turbine generator stator network sideconverter is electrically connected with the motor frequency converter. The method comprises the following steps: initializing a controller; calculating a correlation coefficient; calculating reactivepower given and active power given required during the grid connection of a wind turbine; and carrying out active output and reactive output distribution on the wind turbine generator and the flywheel energy storage unit. The system and the method has the advantages that when the power grid frequency changes, the active output of the wind turbine generator and the flywheel energy storage unit isdistributed according to the influence of the active output change of the wind turbine generator and the flywheel energy storage unit on the grid-connected point frequency, and the output of the windturbine generator is compensated and adjusted; and according to the power grid voltage deviation, the active output and reactive output limitation of the wind turbine generator and the active output and reactive output limitation of the flywheel energy storage unit, the reactive output of a doubly-fed unit and the flywheel energy storage unit is automatically distributed, and the voltage amplitudeof the grid-connected point is improved.

The invention provides a subsynchronous oscillation suppression method for a doubly-fed unit grid-connected system, and a related device. The method comprises the following steps: obtaining a subsynchronous component in a grid-connected current, and converting the subsynchronous component of the grid-connected current to a rotor side, thereby obtaining a rotor side subsynchronous component; and feeding back the subsynchronous component of the rotor side to a current regulator of the rotor side to control the rotor current. The subsynchronous component in the grid-connected current induces thesubsynchronous component on the rotor side, and the subsynchronous component of the grid-connected current is converted to the rotor side, so compared with the prior art, the method has the advantagesthat a group of inverted sub-synchronous components are superposed on the rotor side equivalently, and the inverted sub-synchronous components can induce a group of inverted sub-synchronous components on the stator side, so that the subsynchronous components of stator current on the rotor side are counteracted, the sub-synchronous components introduced by a grid-side converter can be suppressed,and the sub-synchronous oscillation of the doubly-fed unit grid-connected system is suppressed more effectively.

The invention discloses a brushless doubly-fed machine torque ripple minimization control device and a control method thereof. In view of the problems of large torque and flux ripple and unfixed switching frequency of a brushless doubly-fed machine in the traditional direct torque control method, on the basis of analysis of the cause of ripple generated in the traditional direct torque control, the torque and flux at next time are predicted using the idea of predictive control according to the state equation of a brushless doubly-fed machine and the current, torque and flux at the current time, the action time of a non-zero voltage vector is calculated using the principle of minimum torque ripple in one control period, and thus, the torque ripple is reduced. Compared with the traditional direct torque control method, the control method reduces the torque ripple to the maximum extent, quick response and simple control of the traditional direct torque control method are maintained, and the control performance of the system is improved.

The invention discloses a ship shaft generator system and a control method thereof, so as to solve the problems that seamless switching between power generation voltage and a frequency of brushless doubly-fed machine stator and voltage and frequency of a ship power station can not be realized in the prior art and the system can not operate stably when the ship load changes suddenly. The system mainly comprises a grid-connected device (11), an input filter unit (12), a grid-side power unit (13), a machine-side power unit (14), an output reactor (15) and a control system (17), wherein the grid-connected device is connected with the grid-side power unit via the input filter unit; the machine-side power unit is connected with a control winding (3) via the output reactor; and the grid-side power unit and the machine-side power unit are in back-to-back connection. An industrial PC (18) acquires current, voltage, rotation speed and busbar voltage of the brushless doubly-fed machine respectively and the ship shaft generator system is stably controlled. The control method of the invention adopts vector control algorithm and can be used in the ship shaft generator system.

The invention discloses a brushless doubly-fed machine, which comprises a stator and a rotor, wherein stator windings are composed of a power winding and a control winding, the power winding adopts atwo-pole three-phase wiring mode, and each phase has a pole-phase group; the control winding adopts a six-pole three-phase wiring mode, and each phase has three pole-phase groups; the stator is provided with a stator armature core punching groove; and the rotor is provided with a rotor armature core punching groove. The rotor processing process of the brushless doubly-fed machine is simplified, end leakage reactance of the rotor of the brushless doubly-fed machine is reduced, the mechanical strength of the rotor is improved, the insulation performance of an end ring and the motor air gap magnetic field distribution are improved, the machine power factor and the machine operation efficiency are further improved, and the above structure is extremely applicable to a medium or high-power brushless doubly-fed machine.

The invention discloses a predictive power control method and a device of a doubly-fed machine, which comprises the following steps: utilizing the expression of the traditional active power and the expression of the extended reactive power to combine the mathematical model of the doubly-fed machine to generate the expression of the traditional active power differential and the expression of the extended reactive power differential; Using a first order Euler discrete method to discretize the obtained differential expression and calculate a next time power value from the current time power value; Calculating a target rotor voltage vector reference value according to the obtained next time power value by using a deadbeat predictive power control method; By using space vector pulse width modulation (SVPWM) technology, three voltage vectors required for the reference value of the target rotor voltage vector and their action time are obtained, and finally the driving signal for driving the inverter switch transistor is obtained.

The invention discloses a system for improving the low voltage ride-through capability of a doubly-fed pumped storage unit and a control method thereof, and belongs to the technical field of hydropower generation. The system comprises a rotor side controller, which receives a detection signal of a grid voltage detector, adopts a stator flux linkage tracking control strategy when the grid voltage drops, and adopts a vector control strategy when the grid voltage recovers; and the system also comprises grid-side controller, which receives a detection signal of the grid voltage detector, controlsa grid-side converter to work in the working mode of a fault converter when the grid voltage drops, and adopts the working mode of a normal converter when the grid voltage recovers. The system of theinvention inhibits the damage of overcurrent and overvoltage to the unit during the grid fault, helps the grid recover and improves the low voltage ride-through capability of the doubly-fed unit.

The invention relates to a grid-connected control system for a brushless doubly-fed machine. The brushless doubly-fed machine comprises a power winding and a control winding. The grid-connected control system comprises an amplitude control module, a phase control module, a PWM modulator, an inverter and a control module. According to the above grid-connected control system for the brushless doubly-fed machine, the output voltage amplitudes and the phases before and after grid connection of the brushless doubly-fed machine can be ensured to track the power grid-side voltage amplitude and the phase, current impacts in the power winding before and after grid-connected switching can be successfully suppressed, and smooth transition of the switching process is realized.

The invention discloses an equivalent modeling method of a doubly-fed wind power plant considering an auxiliary frequency modulation service. The equivalent modeling method is characterized by comprising the following steps: 1, building a detailed model of the doubly-fed wind power plant; 2, randomly generating the input wind speed of the doubly-fed unit; 3, judging the working mode of the doubly-fed unit participating in the auxiliary frequency modulation service; 4, completing cluster division according to the difference of the auxiliary frequency modulation service working mode, and representing a cluster by using an equivalent quantity; and 5, establishing an equivalent model of the doubly-fed wind power plant. According to the method, accurate representation of the working mode when an internal unit of the doubly-fed wind power plant participates in the auxiliary frequency modulation service of the power grid is realized, and the fitting precision of the equivalent model of the doubly-fed wind power plant for the external power characteristics of the wind power plant is improved.

The invention discloses a high-voltage brushless doubly-fed machine control method, system and device and a readable storage medium. The control method comprises the following steps: obtaining a reference quantity of a frequency conversion winding side of the high-voltage brushless doubly-fed machine; obtaining a frequency change amount according to the reference amount and the electric angle frequency of the frequency conversion winding side; controlling an output target frequency of the frequency converter, wherein the target frequency is the sum of an electric angle frequency and a frequency change amount; acquiring the current reactive current on the frequency conversion winding side; adjusting the output voltage of the frequency converter is adjusted according to the current reactivecurrent and the VF curve so that the current reactive current is equal to the preset reactive current. By compensating the output frequency of the frequency converter, The output voltage of the inverter can be adjusted according to the VF curve and the reactive current of the inverter winding side, so as to control the reactive current of the inverter winding side, the method has strong generalityand high reliability.

The invention discloses a control method and device of a double-fed motor under the working condition of asymmetric depth of a power grid. The method adopts a vector control strategy of double closedloops, wherein an outer loop controls active power and reactive power, an inner loop controls a rotor current, a double-sequence phase-locked loop is utilized to separate positive and negative sequence components of a grid voltage, a given value of a negative sequence of the rotor current can be obtained by directly controlling the negative sequence rotor voltage to be zero according to a steady-state equation of the rotor voltage of a double-fed motor under a reverse synchronous coordinate system, and the rotor negative sequence voltage is reduced by controlling the rotor negative sequence current, so that the amplitude of the rotor voltage is reduced to be within a controlled range of a machine side converter. The control method and device further widen the asymmetric operation range ofthe double-fed machine side converter, and the machine side converter can still be in a controlled state to perform active output and perform reactive support on the power grid under the condition ofasymmetric depth of the power grid.

The invention discloses an excitation control method of an independent generating system of a brushless doubly-fed machine under an asymmetric load. On the basis of positive-sequence and negative-sequence dual dq coordinate systems, a power winding (PW) voltage of a brushless doubly-fed machine is decomposed into a positive-sequence component and a negative-sequence component; a PW voltage positive-sequence component controller and a PW voltage negative-sequence component controller are used for adjusting amplitudes and frequencies of the PW voltage positive-sequence component and the PW voltage negative-sequence component so as to obtain a needed control winding (CW) voltage positive-sequence component and a needed CW voltage negative-sequence component; the CW voltage positive-sequence component and the CW voltage negative-sequence component are added to obtain a final CW voltage given value; according to the given value, a PWM modulation signal and thus an inverter is driven to control the CW; and then the amplitude and frequency of the PW voltage positive-sequence component track the given value respectively and the PW voltage negative-sequence component amplitude converges to zero. With the method, the constant-frequency and constant-voltage generating function of the independent generating system of the brushless doubly-fed machine under the asymmetric load can be realized. Moreover, the control method has advantages of simpleness, high reliability and high robustness.

The invention discloses a multi-frequency converter speed regulation device for a low-voltage large-power multi-branch AC motor, which comprises a brushless doubly-fed machine, a motor connection frequency conversion device and an inverting feedback device, wherein the tail end surface of the brushless doubly-fed machine is provided with a manual control switch; the upper end surface of the manual control switch is provided with a hydraulic resistance speed regulator; the outer part of the hydraulic resistance speed regulator is provided with a frequency converter tachometer; the frequency converter tachometer is embedded with a cage winding-type feedback motor; the cage winding-type feedback motor is connected with a rectifier unit output end via a wire; and the lower end of the rectifier unit output end is provided with a first current detection unit. Through reasonably using the motor connection frequency conversion device, various advanced mechanical devices are applied to achieve beneficial effects of high digital degree and good speed adjustment effects, the service life of the machine is prolonged, the structure is simple, the design is reasonable, and mass production is facilitated.