58 results about "Doubly fed machine" patented technology

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 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 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.