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

The invention discloses a doubly-fed induction generator fault detection method combining a sliding-mode observer and a bilateral cumulative sum algorithm, and the method comprises the following steps: designing a doubly-fed induction generator rotor current sliding-mode observer based on the combination of a novel reaching law and a doubly-fed induction generator state equation; carrying out stability and convergence analysis on the designed novel reaching law by adopting a Lyapunov stability theory; and the fault detection method of the doubly-fed induction generator is designed in combination with the optimized bilateral accumulation sum algorithm. A rotor current sensor fault, an input interference voltage fault, a voltage drop fault and a stator turn-to-turn short circuit fault are introduced. The rotor current tracking performance of the designed sliding-mode observer under different doubly-fed induction generator faults is verified by using a residual value obtained by comparing a doubly-fed induction generator rotor current value estimated by the sliding-mode observer with an actual rotor current output value; and meanwhile, the reliability of the designed doubly-fed induction generator fault detection method based on the optimized bilateral cumulative sum algorithm is verified. The doubly-fed induction generator fault detection method combining the sliding-mode observer and the bilateral cumulative sum algorithm has the advantages of being high in tracking precision and accurate in fault state characterization, meanwhile, weak fault features can be effectively converted into digital signals to be output, and faults of the doubly-fed induction generator are detected.

The invention relates to a self-adaptive fractional order sliding mode control method of a doubly-fed wind power system, solves the problem that chaotic oscillation of a doubly-fed induction generator cannot be effectively suppressed, and belongs to the technical field of wind power generation control. The method comprises the following steps: establishing a chaos sensitive parameter identification model of the doubly-fed induction generator, and estimating system state variables and harmonious scheduling in real time; calculating a chaos intensity index through a chaos phase trajectory prediction module based on a system state variable and harmonious scheduling k; the method comprises the following steps: establishing a fractional order adaptive adjustment mechanism, and dynamically adjusting the fractional order of a fractional order sliding mode surface; according to the method, a fractional order sliding mode surface with a dual-mode switching characteristic is designed; constructing a multi-time scale nonlinear disturbance observer to obtain a total disturbance estimated value; based on the sum fractional order sliding mode surface, designing a chaos feedforward compensator to obtain a feedforward compensation control signal; and performing fusion based on the fractional order sliding mode surface, the total disturbance estimation value and the feedforward compensation control signal to obtain a final control signal.

The invention discloses a low-frequency oscillation optimization method of an electric power system containing an SDC and a DFIG based on balanced truncation and series control compensation. The low-frequency oscillation optimization method comprises the following steps: 1, establishing a linear analysis model of a wind power grid-connected electric power system containing a synchronous generator SG, the DFIG and an additional damping controller SDC; 2, truncation processing is carried out on a state matrix in the state matrix equation of the main system after balance transformation, and a main system state matrix equation after order reduction is obtained; 3, constructing a time domain matrix of the system containing the series feedback controller to obtain a system state matrix equation containing the series feedback controller; 4, solving a characteristic value and a damping ratio of the system state matrix equation containing the series feedback controller, and constructing a control parameter analytic expression of the characteristic value and the damping ratio to the SDC in a low-frequency oscillation mode; and 5, solving by using the low-frequency oscillation optimization model of the SDC to obtain the optimal adjustment amount of the control parameters of the SDC. According to the invention, the control compensator is added to optimize the characteristic value under low-frequency oscillation and the control parameters of the SDC, so that the stability of the system is optimized.

The application discloses a kind of grey-box isomeric doubly-fed wind farm low-frequency oscillation suppression method based on virtual damping modulation, comprising: 1 grey-box isomeric doubly-fed wind farm is divided into white box and black box unit, and the state space model of all white box units of traditional doubly-fed induction generator, virtual synchronous machine control and installation additional damping controller is established;2 improve subspace identification method to obtain black box unit model;3. white box and black box model are coupled by feedback interconnection, and the overall state space model of wind farm is constructed;4 determine target low-frequency oscillation mode based on coefficient matrix;5 real-time extraction and target mode strong correlation common bus power signal, combined with adaptive time-varying gain generates virtual synchronous machine damping coefficient adjustment amount;6 according to complex mode controllability factor and unit distribution coefficient, allocate the virtual damping modulation instruction of each white box unit.The application realizes the identification and suppression of grey-box isomeric doubly-fed wind farm low-frequency oscillation, and improves the ability of wind farm damping low-frequency oscillation.

Systems for replacement of the neutral ring of a rotating electric machine, such as a doubly-fed induction generator (DFIG) useful in a wind turbine, and methods for up-tower repair of the neutral ring. The system generally includes a neutral ring having first, second, and third ring sections formed or two or more laminated layers of copper, and first, second, and third neutral ring connector formed of solid copper. Each of the first, second, and third neutral ring connectors include a cup-shaped fixture extending radially outward from the neutral ring via a riser and are configured for attachment with coils of the winding.

The application discloses a modeling method and device for a fractional order chaotic system of a doubly-fed induction generator, and relates to the technical field of power system chaos modeling. In order to solve the defects that the existing integer order modeling method still has the problems of insufficient modeling precision and difficult parameter solving in describing complex time-varying characteristics and nonlinear coupling behaviors, the technical scheme provided by the application is as follows: including: determining state variables of a preset model through a fractional order differential operator, and constructing a five-dimensional fractional order state differential equation; dimension reduction is performed on the five-dimensional equation by using a stator flux linkage orientation condition, and the five-dimensional fractional order state differential equation is simplified into a three-dimensional fractional order state differential equation; time fast and slow transformation factors are defined, and the preset model is run in a new time scale to optimize the parameter distribution of the state variables; the optimized state variables are converted through a scaling factor of affine transformation to optimize the coefficient distribution of the preset model. The application is suitable for application in the depiction work of the dynamic characteristics of the doubly-fed induction generator.

The invention relates to the field of new energy grid connection and motor system design, and discloses a multi-port motor system for grid connection and a multi-target joint optimization design method thereof. The system adopts a coaxial structure of a doubly-fed induction generator (DFIG) and a permanent magnet synchronous motor (PMSM), and a middle partition plate is arranged to realize magnetic / thermal / electrical isolation; the two rotors are connected through a coupler to form two types of energy channels, namely a mechanical port driven by the PMSM and a DFIG stator leading-out electrical port, and the DFIG stator side is directly connected with a grid. From the aspect of system structure design, a multi-port motor system design model is established, a multi-objective optimization method is adopted to carry out parameter joint optimization under the full working condition of 0-100% power distribution around multiple indexes such as system efficiency, torque quality, vibration suppression, thermal reliability, electric energy quality and port collaboration degree, and the performance of the multi-port motor system can be effectively improved.

A method for drivetrain load mitigation of grid-forming (GFM) doubly-fed induction generator (DFIG)-based wind turbine generator (WTG) based on phase angle feedforward, wherein: acquiring active power of a GFM DFIG-based WTG; calculating difference value between acquired active power of GFM DFIG-based WTG and active power reference value; inputting difference value into GFM control to obtain output signal; adding output signal and reference frequency value of virtual synchronous coordinate system to obtain frequency of virtual synchronous coordinate system; integrating the frequency to obtain output value; multiplying additional damping active power reference value of GFM DFIG-based WTG by control gain of phase angle feedforward control to obtain product result; adding product result and output value to obtain angle of virtual synchronous coordinate system, and based on the angle, obtaining control quantity for generator output voltage phase; based on control quantity, adjusting phase of actual output voltage of GFM DFIG-based WTG by controlling rotor excitation current.

The invention relates to the technical field of wind power grid-connected operation and control, and discloses a rotor overcurrent suppression method and system of a doubly-fed induction generator. The method comprises the following steps: obtaining a rotor current of a doubly-fed induction generator DFIG; separating the rotor current into a fundamental frequency direct current component and an alternating current free component; inputting the fundamental frequency direct current component into a proportional integral (PI) controller, and performing decoupling control of active power and reactive power; inputting the alternating current free component to a vector proportional integral (VPI) controller when detecting that the voltage of the power grid drops, so as to suppress the alternating current free component; and superposing the output of the PI controller and the output of the VPI controller to generate a control signal of a rotor-side converter RSC, and driving the rotor-side converter to realize the suppression of the rotor overcurrent. According to the application, additional hardware devices such as a Crowbar circuit do not need to be added, and the system cost is reduced.