303results about "Generator control circuits" patented technology

The invention provides a double-fed fan broadband oscillation suppression method based on adaptive impedance remodeling, and the method comprises the steps: carrying out the optimization of an RSC current control link for the resonance suppression selection of a subsynchronous / supersynchronous frequency band, adding an adaptive virtual impedance controller, selecting a five-order Butterworth low-pass filter, and carrying out the adaptive improvement of the low-pass filter, the response characteristic in the passband can be adaptively increased along with the frequency, and the characteristic of adapting to the oscillation frequency change is realized; active damping control is added in a GSC current control link for resonance suppression selection of a middle frequency band, and parameter deviation and uncertainty of a controlled object are considered, so that an impedance remodeling effect on the GSC is not influenced by parameters of the converter, and phase compensation can be adaptively performed when the parameters of the converter change. Through frequency-band-division control, the negative damping characteristics of the DFIG in a sub / super-synchronous frequency band and a middle frequency band are improved, a grid-connected system of the DFIG can adapt to different power grid working conditions, and oscillation in a broadband range is effectively restrained.

The invention discloses a method for suppressing subsynchronous oscillation of a doubly-fed grid-connected system, and relates to the technical field of stability control of a power system, and the method comprises the specific steps: S100, extracting the amplitude and phase angle of a subsynchronous frequency component, S200, generating a rotor compensation current instruction according to the amplitude and phase angle of the subsynchronous frequency component and a dynamic gain, and S200, generating a rotor compensation current instruction according to the rotor compensation current instruction; s300, dynamically adjusting the gain according to the suppression ratio and the amplitude of the target magnetic field during operation, S400, calculating the feed-forward decoupling voltage, S500, calculating the suppression ratio after injection, and executing a hierarchical control strategy. Subsynchronous oscillation suppression from the electromagnetic essential level is realized, and by monitoring the subsynchronous component of the air-gap magnetic field in real time and injecting the anti-phase compensation current at the rotor side, the suppression efficiency of the subsynchronous oscillation is improved. Active interference of a stator magnetic field and a rotor magnetic field in a subsynchronous frequency band is cancelled, an energy transfer path of subsynchronous oscillation is directly blocked, oscillation forming conditions are destroyed, and a dynamic gain adjustment mechanism optimizes compensation intensity according to a real-time suppression effect so as to cope with 5-45Hz subsynchronous oscillation frequency change.

A control system configured to control switching of taps of an on-load tap changer provided on an electric power transformer. The on-load tap changer includes switches that are controllable to switch between transformer taps. The control system includes a detector configured to detect an indication of a zero crossing of a transformer voltage of the transformer and a control signal generator configured to generate a control signal that controls a switching of the switches for performing a tap change to a new transformer tap. The control signal generator is configured to determine the timing of the control signal for changing the transformer tap based on the detected indication of the zero crossing of the transformer voltage such that the switching of at least one of the switches for performing the tap change occurs a predetermined time prior to a zero crossing of a tap voltage at the new transformer tap.

The invention discloses an integrated control mode flexible connection switching method applied to a DFIG (Distributed Feedback Induction Generator). The method comprises the following steps of: ensuring that the current limiting performance of a current limiting module can be exerted to the greatest extent in each implementation stage of a control strategy by using the current limiting module; a resistance-capacitance crowbar is introduced to realize current limiting and reactive compensation, switching impact limiting of a control mode is carried out, an input and removal reference mechanism matched with control switching is designed, and then key problems encountered by crowbar use are effectively solved; a state follow-up module is integrated in a DFIG converter control framework, parameter synchronization in the control mode switching process is ensured, the system is effectively prevented from being subjected to great switching impact, and smooth transition of the control mode is further achieved. In the state follow-up period, a network construction control strategy adopted by the RSC of the DFIG provides a reactive compensation reference for the improvement of the GSC, and it is ensured that in the switching process, a tight internal relation is established between different control modes instead of simple time sequence splicing.

The present application relates to the technical field of wind power generation, and discloses a control method and apparatus for a grid-forming doubly-fed wind turbine generator, a generator, and a medium. In embodiments of the present application, a current reference value of a grid connection point is determined on the basis of measurement parameters of the grid connection point in combination with an internal potential parameter of a grid-forming doubly-fed wind turbine generator and a virtual impedance reference value, a voltage reference value of a grid-side converter is further determined on the basis of the current reference value of the grid connection point, and the grid-side converter is modulated on the basis of the voltage reference value, thereby implementing closed-loop control of the grid-side converter, such that a difference between an output voltage value and the voltage reference value of the grid-side converter is less than a preset threshold.

The present disclosure discloses a method for controlling coordinated operation of multiple wind generators to avoid secondary frequency drop. The method includes the following steps: first, the Doubly Fed Induction Generator (DFIG) required for frequency support is dynamically selected based on a real-time disturbance power of a power grid and the rotating speed level of each DFIG; second, the virtual inertial control parameters are adaptively regulated according to the system frequency and the change in the rotating speed of the DFIG participating in frequency support, ensuring that the frequency support requirements are satisfied; and finally, the remaining DFIGs are controlled to release the rotor kinetic energy to support the rotating speed recovery of the selected DFIG, so as to reduce the extra energy absorbed from the power grid in the process.

The invention discloses a network construction type power supply system, a control method and device thereof, a controller and a medium, and belongs to the technical field of electric power. The network construction type power supply system comprises a new energy power generation unit which is connected to a power grid through a power transmission line; and the energy storage unit is connected to a power outgoing line of the new energy power generation unit, is connected with the new energy power generation unit in parallel and then is connected to a power grid, the energy storage unit comprises an energy storage converter, and the energy storage converter is used for controlling the magnitude of the output current of the energy storage unit, so that the total current output by the network construction type power supply system meets the requirements of the power grid. According to the embodiment of the invention, the safety and stability of the power system can be improved.

Systems and methods are provided for controlling two or more linear generators each operating according to a repeated behavior to constitute a cycle. A control system utilizes control circuitry to determine a desired phase offset between operation cycles of a first linear generator and a second linear generator of the two or more linear generators. During operation, an actual phase offset between the first linear generator and the second linear generator is determined. The control circuitry of the control system is used to modify the operation of at least one of the first linear generator or the second linear generator to achieve the desired phase effect.

The invention belongs to the field of new energy power generation equipment, and particularly relates to a doubly-fed wind turbine generator control method and system and a storage medium, and the method comprises the steps: obtaining a real-time angular frequency deviation signal of a power grid, and adjusting the bandwidth of a phase-locked loop when the system frequency deviation is greater than a specified value; a final d-axis rotor current reference instruction is obtained through calculation; calculating a reactive power reference instruction according to the q-axis current reference instruction, introducing a reactive power control link, and calculating a q-axis rotor current reference instruction through a reactive power controller; the doubly-fed wind turbine generator generates a new control signal by an upper-layer control loop based on the new current reference signal, so that the doubly-fed wind turbine generator outputs corresponding active power and reactive power, and rapid active support for the power grid frequency is realized; compared with an existing method for achieving frequency control in a phase-locked loop, the method has the advantages that a differential operator does not need to be introduced, frequency response is fast, the control structure is simple, the bandwidth of the phase-locked loop does not need to be adjusted to a low value, and the accuracy of phase angle tracking of the phase-locked loop is kept.

The invention discloses a wind power plant equivalent virtual inertia identification method based on symbol regression, and relates to the technical field of novel power system frequency safety and stability, and the method comprises the steps: S1, building a doubly-fed fan inertia response dynamic mechanism model containing comprehensive inertia control; according to the method, the problems of lack of physical mechanisms, poor evaluation interpretability and the like of an equivalent virtual inertia evaluation method for a current wind power plant are solved, the method is based on system operation data and is associated with an inertia response dynamic mechanism model, and the interpretability of a system physical process is reserved; a sparse dynamic modeling method is adopted, an input-output linear combination feature library of system electromagnetic torque-rotor rotating speed change is constructed, sparse solution of parameters is achieved through a sequence threshold value least square algorithm, and the equivalent virtual inertia of the wind power plant is obtained through evaluation. According to the method, model priori knowledge and operation data are fully applied, and the evaluation result is high in accuracy and high in interpretability.

The invention belongs to the field of brushless doubly-fed motor control, and particularly discloses a low-bus-capacitor brushless doubly-fed direct-current power generation system direct-current voltage ripple suppression device which comprises a brushless doubly-fed direct-current power generation system, a machine-side converter control system and a direct-current voltage ripple suppression control system. The machine-side converter control system is connected with the machine-side converter and is used for controlling the direct-current bus voltage and suppressing harmonic voltage of a first target number of times of the direct-current bus voltage by adopting a control winding harmonic current compensation method; the direct current voltage ripple suppression control system is connected with the direct current bus and is used for separating harmonic voltage of a first target number of times of the direct current bus voltage and obtaining a harmonic current reference value of a second target number of times of the control winding; the active suppression of the direct-current bus voltage ripple is realized by integrating the harmonic voltage and the harmonic current reference value of the direct-current bus voltage. According to the invention, the system power density is ensured, and the electric energy quality is improved.

The invention provides a zero-voltage ride-through control method for a self-synchronizing voltage source doubly-fed wind turbine generator, which comprises the following steps that: when the self-synchronizing voltage source doubly-fed wind turbine generator is in a transient state, a grid-side converter adopts vector control, and a rotor-side converter adopts additional virtual impedance and annular current limiting; the transient overcurrent of the grid-side converter and the rotor-side converter can be effectively suppressed, so that the continuous operation capability of the wind turbine generator in the zero-voltage ride-through period can be maintained; meanwhile, by improving the transient capacity and the transient reactive current amplitude of the converter, the transient voltage supporting capacity of the wind turbine generator during the zero voltage ride-through period can be effectively provided; when the self-synchronizing voltage source doubly-fed wind turbine generator set is in a transient state, overvoltage of direct-current bus voltage is limited by a Chopper circuit, active-priority current amplitude limiting control is adopted by a grid-side converter, parameters of a current inner ring PI controller of a rotor-side converter are optimized, energy balance of a direct-current side can be achieved in the zero-voltage ride-through period, and stability of the direct-current bus voltage is maintained.

A method of controlling the operation of a doubly fed induction machine is provided. The DFIM includes a stator electrically coupled to a power grid and a rotor rotating with a rotational speed. The DFIM has a synchronous rotational speed of the rotor and a rated rotational speed of the rotor. Rotation of the rotor at the synchronous rotational speed generates one or more slot harmonic distortions having a harmonic order. The method comprises operating the DFIM at the rated rotational speed of the rotor, wherein the rated rotational speed of the rotor is set to a value selected such that a shift of the harmonic order of one or more of the slot harmonic distortions at the rated rotational speed of the rotor is an integer number or is within a predefined limit of an integer number.

The invention discloses a novel oscillation damping control method, which comprises the following steps of: enabling a system to be controlled to be equivalent to a single-input single-output discrete time nonlinear system, and establishing a novel dynamic linearization data model with a pseudo order L based on a plurality of historical output data; calculating a pseudo partial derivative estimated value # imgabs0 # by using input and output data of a to-be-controlled system, and setting different constraint conditions and initial values for different items in a pseudo partial derivative vector; based on a common control input criterion function, a control algorithm fully utilizing historical output data of a system is provided; the first item and the last item of historical output data in the sliding time window are reserved, the other items are sequentially sampled according to a certain interval, and a sparse vector with the length being m (m is smaller than or equal to L-1) is formed again; the influence of historical input signals except the m sampling signals on the system is ignored, and a new pseudo-partial derivative estimation algorithm and control algorithm are obtained. Compared with the prior art, the oscillation suppression effect is better, and the calculation amount and the storage burden are greatly reduced on the premise that the control effect is guaranteed.

The invention discloses a double-fed asynchronous motor synchronous phase locking control method and device. The method comprises the steps that stator three-phase voltage, stator three-phase current instantaneous values and rotor three-phase current instantaneous values of a double-fed asynchronous motor are collected; acquiring a power grid voltage synchronous phase through a phase-locked loop; performing coordinate transformation on the stator three-phase current instantaneous value, the rotor three-phase current instantaneous value and the stator three-phase voltage based on the power grid voltage synchronous phase to obtain a coordinate transformation result; performing flux linkage calculation according to the coordinate transformation result to obtain a flux linkage calculation result; calculating a rotor voltage dynamic compensation item according to a coordinate transformation result and a flux linkage calculation result; performing power calculation according to a coordinate transformation result, and introducing a rotor voltage dynamic compensation item and a flux linkage calculation result according to a power calculation result to calculate and obtain a rotor target voltage reference value of the doubly-fed asynchronous motor; and generating a control signal according to the rotor target voltage reference value to control the doubly-fed asynchronous motor.

The doubly-fed wind turbine generator controller parameter identification method provided by the invention comprises the following steps: establishing a doubly-fed asynchronous generator set system model, and establishing a mathematical model of a doubly-fed wind turbine generator in a synchronous rotating coordinate system; setting a machine side variable current controller in the doubly-fed asynchronous generator set system model, and generating a machine side current transfer function equation containing control parameters; setting a grid-side converter controller in the doubly-fed asynchronous generator set system model, and generating a grid-side current transfer function equation containing control parameters; controlling measures according to faults; according to the doubly-fed wind turbine generator controller parameter identification method provided by the invention, the doubly-fed asynchronous generator set system model is established, the algorithm model is correspondingly generated according to the converter control structure and the fault control structure, and the parameter identification of the doubly-fed asynchronous generator set controller is realized by iteratively solving the nonlinear equation in the model. The control parameters with better fault ride-through response characteristics of the doubly-fed wind turbine generator are obtained, the result is accurate, and the practicability is high.

The invention discloses a double-fed fan low voltage ride through cooperative control method based on power prediction, and belongs to the technical field of wind power generation. The method comprises the following steps: inputting data; performing power prediction based on a CNN-LSTM (Convolution and Long Short Term Memory Neural Network); converter capacity dynamic distribution calculation; the invention relates to an improved direct power control strategy design. According to the method, the CNN-LSTM power prediction model is introduced, so that the problems that traditional direct power control depends on real-time power feedback, a control instruction lags, and consequently, the voltage of a direct-current bus is unstable and reactive power support is delayed during low-voltage ride-through are solved. Through the predicted active power curve, the capacity distribution strategy of the converter is adjusted in advance, so that the reactive power support response is accelerated. Through the adaptive hysteresis control technology, the switching frequency is reduced in the low-voltage ride-through period to protect the device, so that the low-voltage ride-through operation capability of the doubly-fed fan is improved.

A method for controlling a power generating asset having a generator with a stator operably coupled to a transformer and a rotor operably coupled to the transformer via a power converter includes using an angle of a phase-locked loop (PLL) reference signal of a PLL at a PLL reference node of the power generating asset to transform a three-phase set of signals to a two-dimensional orthogonal coordinate system of a synchronously rotating frame. The two-dimensional orthogonal coordinate system includes x and y components of at least one of voltage and current. The method also includes determining one or more dynamic decoupling factors as a function of one or more of the x and y components of at least one of voltage and current. Further, the method includes applying the one or more dynamic decoupling factors to current command calculation logic to mitigate a coupling effect of one or more current command components.

The invention relates to a doubly-fed variable-speed pumped storage unit comprehensive inertia supporting method, device and equipment based on an excitation capacitor. The method comprises the following steps: acquiring a frequency deviation value and a frequency deviation change rate of a grid-connected point after a load connected with a power system is suddenly changed; determining whether to start a comprehensive inertia control strategy according to the frequency deviation value and the frequency deviation change rate; if the comprehensive inertia control strategy is started, dynamically adjusting a DC bus voltage reference value according to the frequency deviation value to determine a d-axis modulation voltage component; acquiring additional electromagnetic increment power; controlling a grid-side converter in the power system to operate according to the d-axis modulation voltage component, controlling a machine-side converter in the power system to operate according to the additional electromagnetic increment power, and providing inertial current impact support for the power system; and if the comprehensive inertia control strategy is not started, the frequency of the power system is kept stable and synchronous, and the doubly-fed variable-speed pumped storage unit of the power system is controlled to work in a constant power state.

The invention discloses a current compensation type three-vector model prediction control method for an off-grid doubly-fed wind turbine generator, belongs to the technical field of doubly-fed wind turbine generator control, and aims to solve the problems of voltage sag and high total harmonic distortion rate of a micro-grid system caused by sudden load change during off-grid operation of the doubly-fed wind turbine generator. The control method comprises the steps that on the basis of virtual synchronous networking control, an off-grid doubly-fed wind turbine generator rotor current prediction model is established, load current, stator side converter current and stator voltage are introduced into three-vector model prediction control, and the voltage coupling effect and current change caused by load abrupt change are compensated in real time, so that the rotor current of the off-grid doubly-fed wind turbine generator is predicted. Obtaining a compensated rotor current reference; a cost function is designed by taking the minimum prediction error of the rotor current as a target, so that accurate prediction of the rotor current during sudden load change is realized, a voltage sag phenomenon caused by sudden load change is effectively inhibited, the harmonic content of output voltage is reduced, and meanwhile, quick response to system frequency and load power is realized.

The invention discloses an enhanced hybrid synchronous control method for a grid-forming doubly-fed wind power converter, and belongs to the field of electrical engineering. The control method comprises enhanced hybrid synchronous control based on a self-adaptive integrator, reactive-voltage droop control and stator voltage and rotor current double-closed-loop control. In order to solve the problem that the resynchronization stability problem of the grid-forming type doubly-fed wind power converter cannot be solved when a traditional grid-forming type converter depends on a hybrid synchronization control algorithm of virtual impedance and is faced with fault scenes such as power grid voltage drop and the like, an existing parameter design method is not suitable for a grid-forming type doubly-fed wind power converter system any more. According to the invention, the voltage synchronization loop based on the adaptive integrator is introduced, so that existence of a stable working point during a fault period is powerfully ensured. And the built adaptive integrator parameter design principle can ensure the synchronous and stable adaptive adjustment capability of the doubly-fed wind power converter under different fault working conditions.

The invention discloses a method and system for suppressing subsynchronous oscillation of a voltage source wind turbine generator, and the method comprises the steps: collecting stator three-phase voltage and stator three-phase current of a doubly-fed generator, and obtaining d-axis and q-axis stator voltage DC components and stator current DC components; obtaining a rotor direct current component; obtaining stator output active power, stator output reactive power, and active power and reactive power after passing through a low-pass filter, and obtaining a compensation instruction of adaptive virtual damping control; outputting a d-axis rotor current instruction and a q-axis rotor current instruction, and obtaining a rotor voltage instruction under the synchronous rotating coordinate system; superposing the rotor voltage instruction and a compensation instruction of adaptive virtual damping control to obtain a new rotor voltage instruction; and after the new rotor voltage instruction and the rotor voltage instruction are modulated by an SVPWM link, a rotor side converter switching tube control signal is generated, so that subsynchronous oscillation suppression of the doubly-fed wind power generation system is realized.

The invention relates to a sending end frequency active support coordination control method for wind power through a high-voltage direct-current delivery system, and belongs to the field of frequency stabilization of large-scale wind power through the high-voltage direct-current delivery system. The method comprises the following steps: firstly, according to unbalanced power caused by power regulation margins and disturbance of various frequency modulation resources, analyzing high-voltage direct current system sending end system frequency support requirements in different scenes; secondly, providing a wind power plant multi-time scale frequency modulation control strategy based on the doubly-fed wind turbine generator and a doubly-fed wind turbine generator and high-voltage direct current system frequency support coordination control strategy considering a frequency modulation dead zone; finally, key control parameters in the control link of the doubly-fed wind turbine generator and the high-voltage direct-current system are designed according to the power regulation margin of the synchronous generator set and the wind power plant, so that inertia support and primary frequency modulation effects can be adaptively switched according to different scenes; the quick response capability of the doubly-fed wind turbine generator and the high-voltage direct-current system is exerted, and meanwhile, the power adjusting capability of each unit is fully utilized.

The invention discloses an AC excitation system no-load voltage buildup and pre-synchronization grid-connected control method and system, and the method comprises the steps: obtaining the amplitude and phase of a power grid voltage in real time through a phase-locked loop when the rotating speed of a doubly-fed induction motor reaches a synchronous rotating speed range; detecting the mechanical position of the rotor by using an encoder and calculating a slip angle; carrying out fundamental component extraction and phase correction on the stator side no-load voltage; setting a stator voltage target value based on power grid voltage directional control and calculating target rotor current; constructing a rotor current inner loop control loop, calculating a feedforward decoupling item and performing phase compensation; superposing a stator voltage outer loop control loop, and correcting the rotor current through closed-loop adjustment to eliminate the deviation between the stator side no-load voltage and the power grid voltage; and when a preset synchronization condition is satisfied, closing the grid-connected circuit breaker and switching a control mode. Accurate no-load voltage buildup and smooth pre-synchronization grid connection of the excitation system are achieved through a double closed-loop control structure, and the stability and reliability of the grid connection process are improved.

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 stable control method and a stable control system for accessing a network construction type heterogeneous power supply to a direct current system, belongs to the technical field of power system control, and solves the problem of serious active power vacancy when an alternating current tie line of an existing multi-source access direct current sending end system fails. The method comprises the steps that energy flow paths among subsystems in the system are analyzed to identify key control links causing instability of the system and orthogonal interaction energy of the key control links, and the orthogonal interaction energy is an interaction energy item which has the largest influence on the stability of the system in interaction energy among modules of the subsystems; based on a minimization principle of total stored energy of the system, coordinating and adjusting a doubly-fed fan active instruction, a direct current system current instruction and an energy storage active instruction in real time; keeping a negative value according to the total interaction energy of the system to compensate the orthogonal interaction energy among the subsystems; and according to the state feedback signal, the active power instruction of each subsystem is dynamically adjusted in combination with the control switching logic. The adaptive capacity and the dynamic recovery performance are improved, and accurate matching and quick response to various fault working conditions are achieved.

The invention discloses a low-voltage ride-through control method considering voltage measurement delay estimation, and the method comprises the steps: carrying out the modeling of a typical vector control system of a doubly-fed wind power system, obtaining a reactive power output limiting condition, and carrying out the building of a voltage measurement equipment output model, on this basis, a cosine interpolation fitting method is adopted to accurately estimate the time delay of a voltage measurement device for the grid-connected point voltage of the doubly-fed fan, and after accurate time delay estimation is determined, the time delay is substituted into a low-order time delay compensation control link, so that the power instruction of the doubly-fed fan is compensated. According to the method, the actual voltage delay of the grid-connected point is accurately estimated, and a voltage measurement delay compensation method is adopted to optimize a voltage control strategy of the doubly-fed fan, so that the problem of overvoltage of the grid-connected point caused by delay of a voltage measurement link is reduced.

The present invention belongs to the field of new energy power generation equipment, and in particular relates to a control method, system and storage medium for a doubly-fed wind turbine generator set, which obtains a real-time angular frequency deviation signal of a power grid. When the system frequency deviation is greater than a specified value, the bandwidth of a phase-locked loop is adjusted; and a final rotor d-axis current reference instruction is calculated; a reactive power reference instruction is calculated based on the q-axis current reference instruction, a reactive control link is introduced, and the rotor q-axis current reference instruction is calculated by a reactive controller; based on the new current reference signal, the doubly-fed wind turbine generator set generates a new control signal by an upper-level control loop, so that the doubly-fed wind turbine generator outputs corresponding active power and reactive power, thereby achieving rapid and active support for the power grid frequency; compared with the frequency control method implemented in the existing phase-locked loop, the method has the advantages of not requiring the introduction of a differential operator, fast frequency response, simple control structure, and no need to adjust the phase-locked loop bandwidth to a lower value, while maintaining the accuracy of the phase-locked loop phase angle tracking.

The invention discloses a doubly-fed motor gravity energy storage system impact stabilizing method and system, and relates to the technical field of gravity energy storage, and the method comprises the steps: collecting the three-phase voltage and current of the stator side of a doubly-fed motor; calculating a power error signal based on the acquired three-phase voltage and current; designing a sliding mode controller based on the power error signal; the change rate of power is calculated through a sliding mode controller, and a control signal is generated; the rotor voltage is calculated through the generated control signal, a PWM voltage signal is generated, feedback is formed for motor power generation, and power closed-loop control of the doubly-fed motor is achieved; according to the invention, the problem of system impact caused by a mass block entering and exiting a track or power step change is effectively solved; and the stability and the response speed of the motor are improved. By the adoption of the control method, the adjustment time of the motor is remarkably shortened, overshoot is eliminated, stator current, rotating speed and power fluctuation are effectively restrained, and the operation stability and safety of the energy storage system are remarkably improved.

The invention provides a multi-target control method for a permanent magnet direct drive fan under an asymmetric fault of a power grid, and solves the technical problems of power fluctuation suppression and current unbalance degree reduction control target coordination optimization in fault ride-through. Comprising the following steps: S1, establishing a positive and negative sequence coordinate system model of a permanent magnet direct-driven wind turbine generator grid-side converter, and carrying out positive and negative sequence separation on voltage and current of the grid-side converter; s2, grid-side converter reference current instructions of the three control targets are calculated; s3, constructing a uniform expression form of the reference current of the grid-side converter; s4, active power fluctuation suppression and negative sequence current suppression are selected as coordinated optimization control targets for control; and S5, constructing a multi-objective optimization function, solving to obtain a current reference value of the converter, and performing current closed-loop control on the grid-side converter. The method has the advantages that multi-target coordination optimization control over the permanent magnet direct-driven wind turbine generator set under the power grid voltage fault is achieved, and the low-voltage ride-through capacity and the grid connection performance of the permanent magnet direct-driven wind turbine generator set are enhanced.