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

The invention discloses a VSG-DFIG subsynchronous oscillation adaptive suppression method based on a Hamiltonian model, and belongs to the technical field of subsynchronous oscillation suppression of a power system. The method aims at solving the problem that an existing method for suppressing subsynchronous oscillation existing in grid-connected operation of the doubly-fed induction generator is poor in suppression effect. Comprising the following steps: constructing a port controlled Hamiltonian dissipation model; constructing a closed-loop system dynamic equation based on interconnection and damping distribution under strict passivity; an expected energy function in a unit closed-loop form is constructed, a DFIG unit feedback control law based on a Hamiltonian model is obtained, and further deformation is carried out to obtain a deformed DFIG unit feedback control law; the port controlled Hamiltonian dissipation model is corrected, and a corrected port controlled Hamiltonian dissipation model is obtained; constructing a dynamic equation of the anti-interference adaptive observer, and establishing an error dynamic equation; and constructing a Lyapunov function, and designing an estimation error feedback control law according to the stability condition of the Lyapunov function. The subsynchronous oscillation suppression circuit is used for suppressing subsynchronous oscillation.

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.

A DFIG wind power facility configured to be operated during grid faults is provided. The wind power facility includes a Doubly-Fed Induction Generator, a control system, an electric converter, a short-circuit controlled switch to selectively short-circuit the stator and a Stator Neutral Brake Chopper coupled to the stator. The DFIG includes a rotor and a stator, the stator including at least one three-phase winding. The electric converter includes a Machine Side Converter, a Grid Side Converter and a DC link connected therebetween. The SNBC includes a three-phase rectifier including three inputs, an impedance and an active high-frequency switch configured to vary the average value of the impedance by adjusting its duty cycle; each of the three inputs of the rectifier is connected to a phase of the at least one three-phase winding of the stator. Methods for operating a DFIG wind power facility during grid faults are also provided.

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.

The invention discloses an electromagnetic transient modeling and simulation method for internal faults of a doubly-fed induction generator, and relates to the technical field of power system modeling and simulation. The method comprises the following steps: S1, considering a stator-rotor turn ratio, and reducing the rotor quantity to a stator side to obtain an original mathematical equation; s2, establishing mathematical models of the doubly-fed induction generator under different fault types, correcting a basic equation of the generator according to fault features, and focusing resistance and inductance matrix elements needing to be updated; s3, selecting a flux linkage as a state variable, performing discretization equivalence on the mathematical equation by using a backward Euler integral method, unifying different faults to obtain an equivalent circuit equation, and constructing an equivalent circuit of the generator; s4, the equivalent circuit of the doubly-fed induction generator is connected with an external electrical network, and the equivalent model carries out node admittance matrix iterative solution on the whole circuit based on an EMTDC solver; and updating other concerned electrical information such as the stator current, the rotor current, the electromagnetic torque, the rotating speed, the rotor angle and the like until the simulation is finished.

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 control system for controlling the operation of a doubly fed induction generator of an electrical power system, such as a wind turbine, is provided. A rotor side converter coupled to a rotor of the DFIG is controlled by the control system. The control system includes an outer controller to generate a reference value for a control variable in accordance with which the operation of the DFIG is to be controlled and an inner controller that receives the reference value and provides feedback control of the rotor side converter. The inner controller is a state feedback controller obtains at least one state of the power system or the power grid that is different from the control variable. The control structure of the state feedback controller causes the electrical power system to act as a passive system at least in a predefined frequency range.

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.

A method of controlling the operation of a rotor side converter (121) of a power generating system (100) of a wind turbine in a grid forming mode is provided. The power generating system (100) comprises a doubly fed induction generator, DFIG, (110) wherein the rotor side converter (121) is coupled to a rotor (112) of the DFIG (110) to control currents in the rotor of the DFIG. The method comprises obtaining a control reference (Vref, Qref) for providing voltage control during operation in the grid forming mode, generating, from the control reference (Vref, Qref), a reference for a magnetizing voltage (eref) of the DFIG (110), receiving a feedback signal indicative of stator voltage (vs) of a stator (111) of the DFIG (100), generating a rotor current reference signal (ir,ref) for a rotor current of the rotor (112) of the DFIG from the magnetizing voltage reference (eref) and the stator voltage feedback signal, and controlling the rotor side converter (121) in accordance with the rotor current reference signal (ir,ref).

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.