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44 results about "Doubly fed induction generator dfig" patented technology

Method and systems for operating a wind turbine using dynamic braking in response to a grid event

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.
Owner:GENERAL ELECTRIC RENOVABLES ESPANA SL

Analysis method of three-phase short circuit current of doubly-fed induction generator after crowbar protection action

The invention relates to an analysis method of a three-phase short circuit current of a doubly-fed induction generator after crowbar protection action and belongs to the technical field of fault analysis of a wind power generation system. The method, by utilizing DFIG stator and rotor voltage equations and stator and rotor flux linkage equations after crowbar protection action, deduces the three-phase short circuit current of the doubly-fed induction generator after crowbar protection action, and thus the calculating process is simplified. The method can accurately calculate the three-phase short circuit current of the doubly-fed induction generator after crowbar protection action, and is of great significance to model selection and protection action characteristic analysis of electric power system equipment comprising the doubly-fed induction generator.
Owner:KUNMING UNIV OF SCI & TECH

Unbalanced voltage compensation device and method for brushless doubly-fed induction generator

The invention discloses an unbalanced voltage compensation device and method for a brushless doubly-fed induction generator, and belongs to the technical field of brushless doubly-fed induction generator control. The device comprises a PW voltage controller, a CW conversion angle generator, a PW voltage amplitude calculator, a PW reactive power compensator, and a CW current regulator. The PW reactive power compensator comprises a PW current converter, a multiplier, a high-pass filter and a resonance controller; the multiplier calculates a current calculation value Qp (n) of the total reactivepower of the brushless doubly-fed induction generator according to the current feedback value ipd (n) of a d-axis component of the PW current and the current feedback value upq (n) of a q-axis component of the PW voltage; and the high-pass filter acquires the current calculation value of the PW double-frequency reactive power from the Qp (n), and the resonance controller calculates the q-axis compensation amount of the CW voltage. The PW reactive power compensator outputs the q-axis compensation amount of the CW voltage to eliminate the PW double-frequency reactive power so that the frequencyand the amplitude of the PW voltage are constant.
Owner:HUAZHONG UNIV OF SCI & TECH

Brushless doubly-fed generator system and control method thereof

The invention discloses a brushless doubly-fed generator system and a control method thereof, and belongs to the technical field of brushless doubly-fed induction generator control. The system comprises a topology module and a control module, wherein the topology module comprises a brushless doubly-fed generator, a two-quadrant converter, a direct-current bus capacitor and a three-phase uncontrolled rectifier bridge. The alternating current side of the three-phase uncontrolled rectifier bridge is connected with the power winding; the direct-current side of the two-quadrant converter and the direct-current side of the three-phase uncontrolled rectifier bridge are connected with the direct-current bus capacitor in parallel. The control method comprises the following steps: providing excitingcurrent according to a PWM pulse modulation signal; controlling the AC voltage output by the power winding side according to the exciting current, and converting the AC voltage into DC voltage through a three-phase uncontrolled rectifier bridge; and inputting the direct-current voltage into the DC/DC converter or the alternating-current grid-connected inverter to supply power to a load or operatein parallel with a power grid. The problem that when an existing brushless doubly-fed generator system is connected to a grid, the power winding voltage, the power grid voltage and the alternating-current side voltage of a grid-side converter are difficult to synchronize is solved.
Owner:HUAZHONG UNIV OF SCI & TECH +1

Stochastic Stability Analysis Method of Power System Containing Wind Power Based on Markov Theory

The invention provides a stochastic stability analysis method for a power system containing wind power based on Markov theory, establishes a Markov model of wind speed and a stochastic dynamic model of a doubly-fed induction generator, and establishes a stochastic Markov dynamic of a power system containing a doubly-fed induction generator Model, put forward the criterion applicable to the system stochastic Markov dynamic model. Based on the stochastic Markov theory, the present invention analyzes the system stability by establishing a stochastic Markov dynamic model of the wind power system. According to the definition of random mean square stability of the system, using the relevant knowledge of the M matrix, the random Markov dynamic model based on the system is used to determine the randomness of the system. Practical criterion of mean square stability; the present invention overcomes the limitations of stochastic equations, and can more accurately describe the dynamic behavior of wind power systems in the case of large-scale random fluctuations in wind speed, based on the stochastic Markov dynamic model derived from the system Compared with other criteria, the criterion is more practical, more concise and has a wider scope of application.
Owner:HOHAI UNIV

Brushless doubly-fed induction generator efficiency optimization control method and system

The invention discloses a brushless doubly-fed induction generator efficiency optimization control method and system, and belongs to the technical field of brushless doubly-fed induction generator control. The method comprises the steps of (1) in a current control period, calculating output power according to a power winding voltage amplitude feedback value and a resistive load value, calculating direct-current input power according to the direct-current bus voltage and the direct-current bus current, and calculating mechanical power converted into input electromagnetic power according to the rotor angular speed and the electromagnetic torque so as to calculate motor efficiency eta of the current control period; (2) if eta is greater than the current optimal motor efficiency, updating the optimal power generation efficiency to eta, updating the optimal power generation frequency to the current power generation frequency f, and then updating a control winding angular frequency given value; and (3) after the power generation frequency is increased by delta f, if the power generation frequency does not exceed the upper limit of the power generation frequency, turning to the step (1) to start efficiency optimization of the next control period, and otherwise, enabling the generator to operate according to the sequence, and ending the optimization control. According to the invention, the motor efficiency can be maximized.
Owner:HUAZHONG UNIV OF SCI & TECH
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