72 results about "Induction generator" 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.

Systems and method to minimize conditions that cause sub-synchronous oscillation (SSOs) associated with series compensated transmission grids. The implementations ensures the correct development of methods and systems that can mitigate sub-synchronous oscillation (SSOs) associated with a series compensated transmission grid and enhance the series compensation efficiency. An example implementation is a network-based SSO mitigation technology, and another example implementation is a generator-based SSO mitigation technology. The discovery and example implementations are applicable to series compensated transmission networks with synchronous generators, induction generators, wind turbines, solar photovoltaic generators, charging stations, battery storage systems, high-voltage DC transmission systems, STATCOMs, inverter-based data centers, and other inverter-based resources.

A transient stability control method and apparatus for a wind-thermal-bundled system. The method comprises: acquiring in real time terminal voltage of a doubly-fed induction generator when the wind-thermal-bundled system experiences a fault (S1); in response to the terminal voltage of the doubly-fed induction generator being within a first voltage sag interval, increasing a reactive current injection coefficient of the doubly-fed induction generator on the basis of a preset adjustment rule, to reduce the swing amplitude of a synchronous generator during an acceleration phase under fault conditions (S2); in response to the terminal voltage of the doubly-fed induction generator being within a second voltage sag interval, increasing the reactive current injection coefficient of the doubly-fed induction generator on the basis of the adjustment rule, to reduce the swing amplitude of the synchronous generator during the acceleration phase and the swing amplitude thereof during a deceleration phase under fault conditions (S3); and in response to the terminal voltage of the doubly-fed induction generator being within a third voltage sag interval, decreasing the reactive current injection coefficient of the doubly-fed induction generator on the basis of the adjustment rule, to reduce the swing amplitude of the synchronous generator during the deceleration phase under fault conditions (S4).

The invention relates to the technical field of wind power, in particular to an anti-overtemperature monitoring system and method for a high-speed shaft brake of a doubly-fed wind turbine generator, and the system comprises an infrared sensor, a PT100 temperature sensor, a two-channel temperature controller, a PLC, an SCADA monitoring system, an infrared sensor support, a miniature circuit breaker and the like. The system monitors the temperature of a brake disc in a non-contact mode and monitors the temperature of a brake pad in a contact mode through double sensors, the temperature is converted into a standard analog quantity signal through a temperature controller, a series detection loop and differentiation threshold judgment are combined, and a PLC outputs an instruction; the method comprises the steps of two-way temperature measurement, signal processing, logic control and remote monitoring, and is adaptive to the potential hazard of heat generation by friction of aging of a brake of an old unit. According to the invention, a double-point redundancy monitoring system is constructed, the defects of single temperature measurement and lack of verification in the prior art are overcome, the reliability and accuracy of overtemperature identification are improved, false triggering is avoided, the operation and maintenance convenience is optimized, and the operation safety of the wind turbine generator is comprehensively guaranteed.

An induction generator (2) is configured for driving an induction circuit (4), in particular for driving an induction coil of an induction hob (30). The induction generator (2) comprises: a power supply unit (8) configured to provide an input voltage (Vi) with respect to a common voltage (Vc); a driving unit (10) configured to provide a first and a second transistor driving voltage (Vg1, Vg2); a half-bridge arrangement (12) comprising a first transistor and a second transistor (14, 16) connected to each other at a middle node (22), wherein the first and second transistors (14, 16) are connected between the input voltage (Vi) and the common voltage (Vc), wherein the first transistor driving voltage (Vg1) is applied to the gate of the first transistor (14), and wherein the second transistor driving voltage (Vg2) is applied to the gate of the second transistor (16); a resonance circuit (4) comprising an induction coil element (6) being electrically connected at one end to the middle node (22) and being configured to emit an electromagnetic field when in operation; a control unit (20) having an output configured to supply a control signal to the driving unit (10) and having an input electrically connected to the middle node (22) configured for sensing the middle voltage (Vm) at the middle node. The control unit (20) is configured to apply the control signal at a setpoint frequency to the driving unit (10) such that via the first and second transistor driving voltages (Vg1, Vg2) a temporal switching sequence is implemented where the first transistor (14) is switched on and off and the second transistor (16) is switched on and off with a delay period (To) between switching off the first transistor (14) and switching on the second transistor (16). The control unit is further configured to detect the middle voltage (Vm) and / or the complimentary middle voltage (Vm*); and to evaluate the amplitude of the middle voltage (Vm) or the temporal behavior of the middle voltage (Vm) in relation to the switching off of the first transistor (14) and / or in relation to the switching on of the second transistor (16), and / or to evaluate the amplitude of the complimentary middle voltage (Vm*) or the temporal behavior of the complimentary middle voltage (Vm*) in relation to the switching off of the second transistor (16) and / or in relation to the switching on of the first transistor (14). The control unit is further configured to increase or to decrease or to maintain the setpoint frequency of the switching sequence being applied via the control signal in dependency of the evaluation. Alternatively or additionally the control unit is further configured to increase or to decrease or to maintain an on-time ratio (Ta / Tb or Tb / Ta), where within a switching sequence Ta is the duration of switching on the first transistor (14) and Tb is the duration of switching on the second transistor (16).

The application discloses a double-fed induction generator rotor speed estimation method based on maximum cross-correlation entropy weighting, and belongs to the field of motor control. The method creatively applies cross-correlation entropy theory to noise covariance estimation of EKF, and designs a complete algorithm system containing dynamic weighting, adaptive kernel bandwidth, mixed robust weighting and numerical reinforcement. The progressiveness is reflected in that the method comprehensively solves the shortcomings of traditional methods in response speed, parameter disturbance resistance and non-Gaussian noise resistance. Theoretical proof and comprehensive simulation experiments prove that the method has better estimation accuracy, robustness and reliability in complex industrial environments such as wind power generation.

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 method for discriminating transient synchronization stability of a multi-wind-power grid-connected system in an asymmetric short-circuit scene, which comprises the following steps of: firstly, calculating positive and negative sequence components of generator end voltage of double-fed wind turbine generators in an asymmetric short-circuit fault of a power grid, and then calculating positive and negative sequence q-axis components of the generator end voltage of each double-fed wind turbine generator; if the positive and negative sequence components of the output current of each unit in the system can be reasonably distributed and the q-axis components of the generator terminal voltage of all the doubly-fed wind turbine generators are corrected to be zero, the transient state of the system is stable under the asymmetric short-circuit fault of the power grid; otherwise, transient synchronous instability of the system occurs. According to the method, the coupling effect caused by control performance and response characteristics of different doubly-fed units between positive and negative sequence networks of the system under the asymmetric short-circuit scene of the power grid is comprehensively considered, and whether transient synchronization of the system is stable or not can be intuitively judged according to the criterion provided by the method.

This invention provides a control method for a doubly-fed induction generator (DFIG) wind turbine with DC-side energy storage grid construction based on hybrid synchronization, belonging to the field of wind power generation and energy storage control technology. This control method calculates and generates modulation voltage commands through a rotor current inner-loop controller based on sampled stator voltage values ​​and reference values, enabling grid-connected operation of the rotor-side converter. Based on the grid-side converter current commands and sampled current values, a switching signal is calculated and generated through a grid-side current inner-loop controller, enabling the grid-side converter to control the voltage across the capacitor. Based on the DC-side battery current commands and energy storage inductor current, the DC-side energy storage bidirectional DC-DC converter is driven through calculation and modulation, achieving active support of the grid frequency by the DC-side energy storage system. This invention achieves inertia support and primary frequency regulation capability, ensuring stable operation of the DFIG wind turbine under weak grid conditions while also improving its grid support capability.

The application provides a double-fed induction generator control system based on a data-driven estimator, comprising a power comparison unit, a PI controller, a rotor current comparison unit, a d-axis filter, a q-axis filter, a d-axis state estimator, a q-axis state estimator, a d-axis data-driven adaptive unit, a q-axis data-driven adaptive unit, a d-axis neural network unit, a q-axis neural network unit, a d-axis controller, a q-axis controller and a double-fed induction generator. The application can accurately estimate system uncertainty and environmental disturbance, adopts a topology structure of a stator side connected to a non-controlled rectification bridge, directly connects a direct current power grid in parallel, controls the motor system by controlling the rotor side inverter to regulate the excitation current, so as to realize direct power control of the double-fed motor direct current power generation system.

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 a new energy positive and negative sequence voltage coordinated optimization method adaptive to high-power fault impact, which comprises the following steps of: constructing an optimal unbalanced voltage suppression model of a doubly-fed wind turbine generator under an asymmetric fault of a power grid, and taking the minimum voltage unbalance degree of a grid-connected point as a target function by the model to suppress the optimal unbalanced voltage of the doubly-fed wind turbine generator under the asymmetric fault of the power grid; the capacity constraint of the rotor side converter and the synchronous stability constraint of the system are included; based on the optimal unbalanced voltage suppression model, reconstructing a double-sequence synchronous rotating coordinate system; carrying out convexity processing on the reconstructed model, relaxing the capacity constraint of the rotor-side converter into a second-order cone form, and introducing an auxiliary variable to convert a target function and related constraints into a standard second-order cone programming problem; and solving the second-order cone programming problem, obtaining an optimal voltage dynamic control instruction, and controlling the new energy generator set. According to the method, the inter-sequence coupling effect can be accurately considered, so that the optimal suppression of the voltage imbalance is realized on the premise of ensuring the safety and stability of a machine-network system.

This application proposes a frequency domain dynamic equivalent modeling method and apparatus for doubly-fed wind farms based on real-time data. The method includes: for a wind farm with k doubly-fed wind turbines, calculating the equivalent rotational speed coefficient η of the kth doubly-fed wind turbine. k ; Calculate the state coefficient STA of the k-th doubly-fed wind turbine. k According to the rotational speed equivalent coefficient η k and state coefficient STA k Calculate the equivalent impedance Z of the k-th doubly-fed wind turbine. Gk (s); based on the equivalent impedance Z Gk (s) The characteristics in the frequency domain are used to determine the stability of the wind farm in the frequency domain. This invention can efficiently and quickly obtain the equivalent impedance of a doubly-fed induction generator (DFIG) wind farm at various time periods, and the results provide an important basis for the analysis of the impact of wind farm grid connection.

This invention relates to the field of new energy grid-connected control technology, and particularly to a method and apparatus for identifying control modes and parameters of a doubly-fed induction generator (DFIG) converter. The method involves applying small-amplitude step or pseudo-random voltage disturbances at the turbine terminal or grid connection point, collecting three-phase voltage and three-phase current data at the grid connection point, and obtaining the input vector and measurement output vector in a synchronous rotating coordinate system through Park transformation. An augmented state-space model library containing multiple potential control modes is established, and the PI parameters to be identified are incorporated into the augmented state. Unscented Kalman filters are run in parallel for each model to estimate the state / parameters, calculating the innovation residuals and their covariance. Based on Bayesian inference, the posterior probabilities of each model are recursively updated and normalized. The model with the highest probability is selected to determine the control mode, and the corresponding parameter estimates are output. This method does not require preset modes, improves identification accuracy and parameter physical consistency during mode switching or critical operating conditions, and facilitates stability analysis and operating condition migration. It has wide applicability.

This invention provides a grid-actively supported doubly-fed induction generator (DFIG) wind turbine control system, comprising: a DFIG converter power generation system, a wind turbine primary frequency regulation control module, a wind turbine autonomous inertia response control module, a wind turbine autonomous voltage control module, a rotor-side converter current command generation module, a rotor-side converter current control module, a rotor-side converter signal processing module, a grid-side converter synchronization angle control module, a grid-side converter AC voltage amplitude control module, a grid-side converter current command generation module, a grid-side converter current control module, and a grid-side converter signal processing module. Based on the principle that both the turbine-side and grid-side converters of the DFIG wind turbine employ amplitude and phase control, this invention achieves active support control of the grid frequency and voltage by the DFIG wind turbine unit through active primary frequency regulation, inertia response, and autonomous voltage regulation control strategies, without relying on communication with the power station controller.

An electrical machine comprising a rotatable shaft; an induction generator mechanically coupled to the rotatable shaft and defining a power output connectable with an electrical load, wherein the power output defines a desired constant voltage output; a converter electrically connected with the power output; and a controller connected to the converter, the controller configured to at least one of provide supplemental power at the power output or absorb excess power at the power output.

This application provides a variable parameter frequency regulation method, apparatus, and electronic device, relating to the field of power system technology. The method includes: acquiring the load power change of a doubly-fed induction generator (DFIG) with a flywheel energy storage unit; obtaining real-time parameter optimization constraints based on the load power change, a time-delay frequency response model, preset frequency constraints, the expression for the minimum frequency point, and the steady-state frequency expression; the time-delay frequency response model characterizes the time-delay dynamic relationship between the frequency change and the load power change within the DFIG with a flywheel energy storage unit; obtaining a target droop coefficient and a target inertia coefficient that meet the real-time parameter optimization constraints through iterative calculation; and sending the target inertia coefficient and target droop coefficient to the DFIG with a flywheel energy storage unit, so that the DFIG with a flywheel energy storage unit determines a compensation power value based on the target inertia coefficient and target droop coefficient, and adjusts the power according to the compensation power value. This achieves safe and rapid primary frequency regulation with variable parameter optimization control.

The invention discloses a dual-winding induction generator energy storage cooperative power supply system and a transient frequency guidance control method thereof, and belongs to the technical field of generator control, and the method comprises the steps: giving a power value based on a dual-winding induction generator mode instruction, and obtaining a corresponding slip; according to the obtained slip, a frequency guiding function is introduced, and a dynamic sliding mode surface is constructed; carrying out derivation on the dynamic sliding mode surface, and constraining a derivative based on an approaching rate of a second-order superspiral sliding mode algorithm; obtaining an energy storage power change rate calculation formula according to the approaching rate and the frequency inertia equation; calculating the output power of the generator according to the energy storage power change rate and the load power; and converting the output power of the generator into a corresponding electromagnetic torque reference value to be input into a power supply system. According to the transient frequency guide control method for the energy storage cooperative power supply system of the duplex-winding induction generator, the power output of the duplex-winding induction generator is improved, the transient frequency drop caused by direct switching is avoided, and the power supply quality of the system is improved.

This invention discloses an inertia-adjustable grid-connected device and control method for reducing motor-to-ground voltage. The device comprises an even number of motor grid-connected interface devices connected in series between the positive and negative buses of a bipolar DC-DC converter. The intermediate node of each even number of motor grid-connected interface devices is grounded to reduce the motor-to-ground voltage. Each motor grid-connected interface device includes a doubly-fed induction generator (DFIG), a first DC / AC converter, a permanent magnet synchronous motor (PMSM), and a second DC / AC converter. The positive terminal of each motor grid-connected interface device is connected to the positive DC side of both the first and second DC / AC converters, and the negative terminal is connected to the negative DC side of both the first and second DC / AC converters. This invention aims to reduce the ground voltage of both the DFIG and PMSM, lower insulation requirements, extend insulation life, and improve the stability and reliability of the electrical system.

The invention discloses a doubly-fed flywheel energy storage-based network following-construction fusion control method, which comprises the following steps of: 1, acquiring electrical parameters of a stator and a rotor of a doubly-fed fan, performing coordinate transformation to obtain dq-axis components, and calculating real-time output power of the stator; 2, a virtual internal potential phase is generated through virtual synchronous control, a phase-locked loop obtains a power grid phase, modulation voltage reference values are output respectively, and a final modulation voltage reference value is obtained through weighted sum so as to realize dynamic fusion control of network following and network construction characteristics, and in the network following control, a modulation voltage is obtained through a rotating speed-active and reactive outer loop and a current inner loop, and the current inner loop is added to the rotating speed-active and reactive outer loop; in the network construction control, instantaneous power is calculated through electrical parameters, a reference phase and voltage are obtained through virtual synchronous control, and modulation voltage is output through a single voltage loop. According to the method, the characteristics of the network following current source and the network construction voltage source are fused, advantage complementation is achieved, the method has fast power adjustment and power grid supporting performance, the method is adaptive to a wide-short-circuit-ratio power grid scene, and therefore the weak power grid stability and the new energy consumption capacity can be effectively improved.

This invention relates to the field of frequency control technology for new energy systems, and particularly to a method and system for online identification and evaluation of virtual primary frequency regulation for wind and solar turbine units. The method includes: determining the steady-state output power benchmark, maximum available power, and reserve capacity of the doubly-fed induction generator (DFIG) and photovoltaic (PV) units; collecting frequency data and active power data at the grid connection point and preprocessing them to obtain time-series data; dividing the time-series data into stages, and identifying the actual effective parameters corresponding to the virtual primary frequency regulation control components online during the steady-state frequency regulation stage; identifying the actual effective parameters corresponding to the virtual inertial control components online during the transient inertial stage; and evaluating the validity of the parameters based on the actual effective parameters, reserve capacity, and controller preset parameters to determine whether the DFIG and PV units have entered a power saturation state. This invention effectively solves the problem that existing new energy units easily enter a power saturation state under large disturbance conditions, causing theoretical control parameters to fail to reflect actual frequency regulation capabilities.

An electrical machine comprising a rotatable shaft; an induction generator mechanically coupled to the rotatable shaft and defining a power output connectable with an electrical load, wherein the power output defines a desired constant voltage output; a converter electrically connected with the power output; and a controller connected to the converter, the controller configured to at least one of provide supplemental power at the power output or absorb excess power at the power output.

This invention discloses an online identification method and system for dual inductor parameters of a doubly-fed induction generator (DFIG) MRAS position observer, belonging to the field of sensorless control for doubly-fed variable-speed pumped storage. The method includes: a stator leakage inductance coefficient identification step and a mutual inductance coefficient identification step. The stator leakage inductance coefficient identification step includes: performing coordinate transformation on the position observed by the observer, the α' component and β' component of the rotor current to obtain the identified q-axis component of the rotor current; constructing a stator leakage inductance coefficient identification formula for identifying the stator leakage inductance coefficient to obtain the stator leakage inductance coefficient identified at the current moment; the mutual inductance coefficient identification step includes: using the stator leakage inductance coefficient identified at the current moment to perform online mutual inductance coefficient identification to obtain the mutual inductance coefficient identified at the current moment. This invention pertains to online identification of mutual inductance and stator leakage inductance coefficients under sensorless control conditions, which can improve the accuracy of the MRAS position observer and ensure the power control performance of the doubly-fed variable-speed pumped storage unit.

This invention discloses a grid-connected frequency control method for a doubly-fed induction generator (DFIG) based on a fractional-order adaptive virtual synchronous generator (VSSG), belonging to the field of wind power grid-connected control technology. The method first establishes a mathematical model for DFIG grid connection and monitors grid frequency and active power in real time. Second, it constructs a grid-side VSG control model, analyzes the influence of rotational inertia J and damping coefficient D on the system's dynamic response, and designs adaptive VSG control. Based on this, fractional-order control theory is introduced, and a fractional-order VSG control module is designed. The system's frequency regulation performance is optimized using a non-integer-order differential operator. Finally, the controller parameters are optimized to achieve rapid dynamic response and frequency stability. By combining fractional-order control and adaptive VSG strategies, this invention effectively suppresses power oscillations and frequency overshoot during grid frequency fluctuations, improving the frequency support capability and transient stability of the DFIG grid-connected system. It is suitable for frequency control applications in power systems with a high proportion of renewable energy integration.

This invention discloses a method and apparatus for determining the optimal position of the shaft damping controller in a grid-type doubly-fed induction generator (DFIG). A damping controller based on rotational speed signals is added to different control loops. The differences in shaft damping caused by adding the damping controller to different control loops are compared based on the root locus diagram of the DFIG. Results show that implementing the damping controller in the active power loop reduces transmission system damping compared to the voltage loop. Furthermore, applying the damping controller to the q-axis voltage provides a better damping enhancement effect than applying it to the d-axis voltage.

This invention relates to a self-powered vibration control and monitoring device using a surrounding steel rope for hydraulic pipelines. The device includes a steel rope, pulley bearings, a steel rope fixing and adjusting device, a mounting frame, an oscillator, a coil, a magnet, an energy management and controller, and a vibration sensor. The steel rope wraps around the pulley bearings and is wound around the mounting frame. The oscillator is constrained within the mounting frame, the coil is wound around the oscillator, and the magnets are nested at both ends of the mounting frame. When the hydraulic pipeline vibrates, the oscillator suppresses the vibration, the coil generates electricity, and the electricity powers the vibration sensor. The data collected by the vibration sensor is processed by the energy management and controller and then transmitted to the processing end for analysis. Compared with existing technologies, this invention has the advantages of reducing the radial vibration amplitude of the hydraulic pipeline, converting vibration into electrical energy to power the sensor, achieving real-time self-powered monitoring of the hydraulic pipeline vibration state, and improving energy harvesting efficiency by using an electromagnetic induction generator mechanism.

An object of the present invention is to provide an electric power generation system that can stably control, with one electric power converter, output electric power of a main winding and an auxiliary winding of a dual-winding induction electric power generator. For this purpose, in an electric power generation system including an electric power generator having a stator including a main winding and an auxiliary winding, a rectifier connected to the main winding, an electric power converter that is connected to the auxiliary winding and controls voltages of the main winding and the auxiliary winding, and a controller that outputs a control signal according to a voltage command value of the auxiliary winding to the electric power converter, the controller calculates a voltage change amount of the auxiliary winding generated by interference of a magnetic flux of the main winding with the auxiliary winding, on the basis of a current and the voltage of the main winding, and adds the voltage change amount to the voltage command value of the auxiliary winding.

A method of controlling an induction generator (3) connected to a utility grid (47) is described, the method comprising: receiving an actual grid frequency (f); and controlling a rotor winding (15) of the generator (3) by rotor control signals (25a, b, c) having a rotor winding reference frequency (Ω_ref) set in dependence on the actual grid frequency (f).

This utility model discloses a voltage sampling interface protection device for a doubly-fed induction generator (DFIG) converter in a wind turbine generator set, relating to the field of wind power equipment technology. It includes a fusible link fuse, a DC bus voltage sampling interface, a capacitor voltage sampling interface, a stator voltage sampling interface, and cables. It also includes a DIN rail bracket. The fusible link fuse is fixedly installed in the external terminal box of the DFIG converter control box via the DIN rail bracket. Three sets of fusible link fuses are connected in series on the voltage divider circuit side at the front end of the DC bus voltage sampling interface, the capacitor voltage sampling interface, and the stator voltage sampling interface, respectively. A protective component is installed at the cable through-hole. This device features an optimized structure, with the addition of fusible link fuses to enhance the protection characteristics of the converter grid-side voltage sampling interface, quickly cutting off short-circuit current and preventing fault propagation. The cable through-hole uses a special protective sleeve to prevent cable damage due to vibration or external force. The modular design of the fuse via the DIN rail and bracket simplifies the fuse replacement process and facilitates maintenance.

This invention discloses a control method for improving the transient stability of doubly-fed induction generator (DFIG) wind turbine systems connected to the grid, belonging to the fields of wind power grid connection technology and power system stability control technology. First, a reduced-order model of the system is established to accurately reflect the dynamic behavior during low-voltage ride-through. Based on this model, the attraction domain boundary and maximum power angle constraint are obtained, and then adaptive current reference control is proposed: the rotor d-axis current limit is calculated based on the maximum power angle constraint and the grid voltage, and compared with the original reference generated by maximum power point tracking. The smaller value is taken as the command to achieve adaptive limiting of the rotor current. Simultaneously, transient pitch collaborative control is proposed: the rotor speed is monitored in real time, and when the speed exceeds the safe upper limit, a transient load reduction power command is calculated and the pitch angle is rapidly increased to reduce mechanical torque. This invention can significantly enhance the fault ride-through capability and grid-connected operation reliability of DFIG wind turbines during transient processes such as voltage dips.