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

In order to carry out fault detection on the doubly-fed induction generator, the invention provides a doubly-fed induction generator fault detection method based on a sliding mode observer. Because asliding mode observer is simple in structure, is not liable to be affected by parameters, is high in anti-interference capability, and the like, the sliding mode observer is used for the fault detection of the doubly-fed induction generator. Firstly, a sliding mode observer is built according to a mathematical model of the doubly-fed induction generator, the rotor current and the rotating speed ofthe doubly-fed induction generator are observed, and self-detection of faults is achieved by comparing the residual error between the actual rotor current value and the observed value, then three faults of a power grid end voltage drop fault, a doubly-fed induction generator stator turn-to-turn fault and a rotor current sensor fault are given so as to prove that the sliding-mode observer can wellperform fault detection on faults occurring at different positions, and the sliding-mode observer has the characteristics of the high response speed, the good stability and the like.

Aspects of the present invention relate to a method for controlling an amount of reactive current provided from a wind turbine generator to a power grid during an abnormal power grid event, said wind turbine generator comprising a doubly-fed induction generator having a rotor and a stator, and a power converter coupling the rotor to the power grid, the power converter comprising a grid-side inverter, wherein the method comprises the step of balancing the reactive current provided to the power grid between a reactive stator current and a reactive grid-side inverter current, wherein the reactive grid-side inverter current is controlled in accordance with a reactive current capacity of a grid breaker receiving the reactive current provided by the grid-side inverter. Aspects of the present invention also relate to a wind turbine generator being capable of performing the method.

Systems and methods for allocating reactive power production in a doubly-fed induction generator (DFIG) wind turbine system including a DFIG and a power converter including a line side converter and a rotor side converter are provided. A method can include obtaining a reactive power production requirement, obtaining one or more operating parameters for the DFIG and the line side converter, and determining a priority ratio based at least in part on the one or more operating parameters. The priority ratio can be a ratio of reactive power production between the DFIG and the line side converter. The method can further include controlling the DFIG and the line side converter based at least in part on the reactive power production requirement and the priority ratio such that the combined reactive power production from the DFIG and the line side converter meet the reactive power production requirement.

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.

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.

The present invention relates to a method of controlling a doubly fed induction generator wind turbine converter system in case of a sub-synchronous resonance event, the method comprising the steps of detecting the sub-synchronous resonance event, and switching from a first control mode to a second control mode in response to detecting the predetermined event, wherein the second control mode comprises the step of setting at least one rotor current controller parameter on the basis of a generator speed of the doubly fed induction generator. The predetermined event may also be a fault ride through event. The present invention further relates to a doubly fed induction generator wind turbine converter system being capable of handling such events.

The invention discloses a parameter-free prediction current control method of an independent brushless doubly-fed induction generator, and belongs to the technical field of brushless doubly-fed induction generator control. The method comprises the following steps: monitoring control winding voltage and current information of a motor at the first two moments and the current moment in real time; calculating a prediction current containing delay compensation, determining an optimal switching state of a power electronic device in a control winding side converter through a cost function, and finally determining a duty ratio by using a single vector modulation algorithm to generate a reasonable and effective switching sequence so as to drive the control winding side converter to realize real-time control of a control winding current. According to the control method, the winding current is predicted and controlled through the real-time motor state information, dependence on motor parameters can be effectively avoided, a control system is hardly influenced by motor parameter changes, robustness is high, and operation is more stable.

The invention discloses a distributed state fusion estimation method for a wind driven generator under the condition that noise statistical characteristics are unknown. The distributed state fusion estimation method comprises the steps of: proposing a mathematical model of a doubly-fed induction generator; establishing a state space model of the generator; designing a distributed fusion estimationmethod with unknown noise statistical characteristics; setting motor parameters, and solving two optimization problems to obtain a local optimal gain and a distributed weighted fusion matrix; and performing iterative updating to obtain fusion estimation of a generator state. The new distributed fusion estimation method is provided by the invention for solving the state estimation problem of the wind driven generator when the noise statistical characteristics cannot be accurately obtained, and is high in estimation precision.

A control method for the rotor side converter of a doubly-fed induction generator in a wind turbine for disturbances in the electric grid is provided. A control system includes a calculating unit configured for calculating at least one reference current. A current controller which is a hybrid controller configured to operate in two different modes, a first operating mode, set during a transient of a disturbance in an electric grid, where the current controller is configured to operate with a modulation index being outside a linear area and a second operating mode, set during a stable state of the disturbance in the electric grid, where the current controller is configured to operate with a modulation index inside the linear area, thereby instantly providing a maximum voltage available in a rotor so as to satisfy the at least one reference current.

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.