1475 results about "Current loop" patented technology

The present invention relates to the technical field of secondary device monitoring. Disclosed are an online monitoring method for an operating state of a secondary current loop neutral line, and a system. The method comprises: by using a high-precision sensor for collection and a composite filtering algorithm for processing, obtaining a secondary current fundamental component of each neutral line of a transformer substation which is not influenced by harmonic waves and transient states, and uploading the secondary current fundamental component to a protection information master station; retrieving originally configured access protection information master station information to obtain three-phase secondary current loop information of each bay of the transformer substation, summarizing secondary current information of all monitoring ranges, and performing grouping and classification marking on said information by transformer substation, bay and winding; and using the collection information for operation analysis, automatically identifying and confirming an operating state of the line, and on the basis of the operating state, calculating the outlier deviation linearity and the continuous dynamic trend deviation degree of each winding of each bay. The present invention solves the problem that intermittent faults in secondary current loop neutral lines are concealed and are not easily found, realizes comprehensive monitoring for the whole system, and can quickly and accurately position a specific winding and issue an abnormal early warning.

The invention discloses a fault ride-through hierarchical control method for a network-constructed converter, and the method comprises the steps: introducing a virtual resistor formed by fault current negative feedback into the voltage and current inner loop control of the network-constructed converter based on VSG control through a current inner loop dynamic amplitude limiting control layer after the converter enters a fault ride-through state, the size of the virtual resistor is adjusted in real time along with the amplitude of the fault current so as to carry out dynamic current limiting control on the virtual resistor; and the power outer loop dynamic compensation control layer dynamically adjusts an active power instruction value and a reactive power instruction value of the network construction type converter based on VSG control during the fault ride-through period according to the voltage drop degree of the power grid after the converter enters the fault ride-through state. And respectively performing active-frequency control and reactive-voltage control based on the active power instruction value and the reactive power instruction value. In addition, the method also comprises a state coupling and parameter self-adaption module. According to the method, the GFM converter can have better dynamic performance in the fault recovery stage.

The invention relates to the technical field of industrial automation control, and discloses a change gear assembly processing technological parameter intelligent optimization system, which comprises a multi-dimensional data synchronous acquisition unit, an angular domain static map construction unit, a phase lead constraint control unit and an angle trigger execution unit, according to the method, a static angle-load topological graph with a main shaft angle as an index is established, a phase lead angle is calculated by combining inherent physical response lag time of a servo system, and a parameter adjustment instruction sequence is directly injected into a servo current loop at a preset angle window before physical load impact occurs; according to the feed-forward control mechanism based on angular domain reconstruction and phase lead constraint, the problem of physical lag of traditional time domain feedback control in response to high-frequency intermittent cutting is avoided, and zero time difference of periodic load impact and even pre-judgment torque compensation are achieved.

The invention provides a field data verification device based on a money-free clamp buckle type single-phase electric energy meter, and the device comprises a host which is used for starting a measurement process through the contact of a probe with a signal contact of the electric energy meter, receiving current data transmitted by a wireless clamp-shaped current transformer, and carrying out the filtering, calibration and error analysis of the measurement data; and the wireless split core type current transformer is used for being clamped on a current loop of the measured electric energy meter, starting to measure current data and sending the current data to the host in a wireless mode. According to the invention, a wireless communication technology, a field data processing algorithm and a verification function are integrated, and field real-time data acquisition, processing, analysis and verification can be realized, so that the efficiency and accuracy of verification work are improved.

The invention relates to a dual three-phase permanent magnet synchronous generator rectification system and a direct current voltage stabilization control method thereof. Comprising a dual three-phase permanent magnet synchronous generator, a VSD decoupling converter, a load current observer, a dynamic load feed-forward compensator, a voltage closed-loop controller, a dead-beat predictive current controller, a maximum four-vector SVPWM modulation module and a six-phase rectifier. The double-three-phase topological structure adopted by the invention has the advantages of multiple control degrees of freedom, high reliability and the like. A dynamic load feed-forward compensator is constructed to perform dynamic feed-forward compensation on quadrature-axis current of the motor, so that the recovery time of bus voltage is shortened, and the voltage fluctuation amplitude is reduced; the designed dead-beat predictive current controller optimizes the dynamic characteristics of a current loop, improves the torque tracking performance of the motor, and further improves the voltage stabilization regulation capability of the system. The designed load current observer realizes the analysis redundancy of current detection and improves the reliability of the system.

The embodiment of the invention discloses a midpoint potential control method based on a diode clamping type three-level grid-connected inverter and a related device. The method comprises the following steps: generating an initial three-phase modulation wave through a current loop closed-loop control method according to a collected three-phase current value and a three-phase voltage value of a power grid side of the diode-clamped three-level grid-connected inverter; according to an initial modulation waveform generated by the initial three-phase modulation wave, a three-phase current value and an acquired voltage value of a voltage dividing capacitor at the direct current side of the diode clamping type three-level grid-connected inverter, calculating a zero-sequence component required by neutral-point potential balance; superposing a zero-sequence component required by neutral-point potential balance with the initial modulation waveform to obtain a final modulation wave; and generating a driving signal matched with each phase of bridge arm in the diode clamping type three-level grid-connected inverter according to the final modulation wave. By adopting the invention, the neutral-point voltage can be balanced, the distortion of the output waveform at the alternating current side is reduced, the voltage stress of the device is reduced, and the service life of the power device is prolonged.

The invention provides a self-adaptive constraint model active mismatch prediction control method based on voltage and current ripple resistance of a power converter in a hybrid energy storage system, and the method comprises the steps: building an island DC micro-grid system model, collecting the voltage and current information of a system, and designing a model prediction control frame of a power loop and a cost function of the model prediction control frame; designing a model predictive control framework of the current loop and a cost function of the model predictive control framework; designing an active model mismatch mechanism to enhance the response capability to dynamic change; determining an optimization problem with a normal value, and designing an adaptive constraint optimization algorithm to dynamically adjust constraint parameters and optimize control performance; and designing a steady-state and dynamic-mode trigger for adapting to the running state of the system. According to the invention, the trajectory tracking precision of the system under dynamic and steady-state working conditions can be significantly improved, current ripples caused by control delay can be effectively eliminated, damage to electrical equipment due to overlarge ripples can be avoided, and the service life of the equipment can be prolonged.

Aiming at the stability problem caused by harmonic resonance of multiple parallel photovoltaic inverters, the invention provides a parallel inverter micro-grid-oriented adaptive virtual impedance remodeling harmonic resonance suppression method, which comprises a virtual impedance remodeling unit of a grid-connected inverter, a parameter adaptive adjustment unit and a power grid impedance online detection unit. The virtual impedance remodeling unit can improve the output impedance characteristic of the grid-connected inverter and inject a certain damping component into the micro-grid; and the parameter adaptive adjustment unit adaptively adjusts control parameters in the virtual impedance remodeling unit and the current adjustment controller according to the impedance parameters of the power grid so as to maintain the stability of a system control loop. The power grid impedance online detection unit provides power grid equivalent impedance as the input of the parameter adaptive adjustment unit. The three units work cooperatively to form a self-adaptive virtual impedance remodeling multi-inverter micro-grid harmonic resonance suppression strategy, so that the characteristics of a current loop are improved, the inverters can be kept stable under various grid impedance conditions, and the reliability of a multi-inverter micro-grid system is improved.

The invention relates to the technical field of motor control, and particularly provides a permanent magnet synchronous motor current harmonic disturbance suppression method and a motor system.The permanent magnet synchronous motor current harmonic disturbance suppression method comprises the steps that firstly, a permanent magnet synchronous motor mathematical model considering harmonic disturbance under the d-q axis of a synchronous rotating coordinate system is constructed, and a theoretical basis is provided for subsequent control strategy design; an improved resonance controller is set and embedded into the extended state observer, comprehensive estimation of d-q axis non-periodic disturbance and periodic harmonic disturbance is achieved, finally, an enhanced current loop active disturbance rejection controller based on the improved resonance-extended state observer is built, unexpected peak values are eliminated, and the disturbance rejection rate of the current loop is improved. And comprehensive suppression of aperiodic disturbance and periodic disturbance is realized. According to the method, aperiodic and periodic disturbance can be suppressed, unexpected peak values are eliminated, system instability caused by noise amplification is avoided, and the steady-state performance and robustness of current control of the permanent magnet synchronous motor are remarkably improved.

The invention discloses a decoupling control method and system for a matrix motor with harmonic suppression capability, and belongs to the technical field of motor driving systems, and the method comprises the steps: building a matrix motor current loop mathematical model which considers a DC disturbance term and an AC disturbance term at the same time; based on the matrix motor current loop mathematical model, establishing a self-adaptive quasi-resonance extended state observer which simultaneously considers direct current disturbance observation and alternating current disturbance observation and performs self-adaptive adjustment on control parameters; the direct current and alternating current lumped disturbance of a matrix motor current loop is observed in real time through an adaptive quasi-resonance extended state observer; compensating the observed direct current and alternating current lumped disturbance in a forward controller of the current loop and obtaining a voltage control quantity; and controlling the matrix motor through a voltage vector space transformation and SVPWM modulation method according to the voltage control quantity. The method is improved and optimized based on an existing matrix motor vector control system, and the system does not need to be modified on a large scale.

The invention discloses a dual three-phase permanent magnet motor current control method and system under high speed and low carrier wave ratio, and belongs to the technical field of permanent magnet motor control. The method mainly comprises the following steps: reconstructing a motor mathematical model by adopting VSD conversion and Park conversion; designing a linear expansion state observer; a reference value of an output voltage vector is obtained in combination with deadbeat predictive current control; and performing time delay compensation and angle delay compensation on the output voltage vector to obtain a reference value of a final output voltage vector, sending the reference value to an SVPWM module for modulation, and outputting a PWM pulse signal for driving a motor. No motor parameter is used in the current loop design process, system errors caused by mismatching of the motor parameters can be avoided, and the system robustness is improved; meanwhile, only one control parameter needs to be determined, the parameter setting difficulty is greatly reduced, and stable operation of the high-speed permanent magnet motor under the low carrier wave ratio is achieved.

The invention discloses a protection circuit, a control method and a photovoltaic system, and belongs to the technical field of power electronics. The invention provides a protection circuit which is applied to a three-phase inverter circuit, the direct current side of the three-phase inverter circuit is used for being connected with a power supply assembly, the output end of each phase is provided with a relay assembly, and the protection circuit comprises a controllable power device which is connected with a bridge arm in the three-phase inverter circuit in parallel; the fault detection module is electrically connected with the three-phase inverter circuit and is used for generating a fault signal when the fault of short circuit to ground is detected; the current detection circuit is used for detecting the output current of each phase of the three-phase inverter circuit; and the controller is electrically connected with the fault detection module, the current detection circuit and the relay, controls the controllable power device to be switched on after receiving a fault signal, and disconnects the relay assembly of each phase when the output current of each phase meets a zero-crossing condition, so that the relay assembly can be ensured to be switched off safely, and a loop of short-circuit current can be cut off. And the short-circuit current is prevented from damaging components in the circuit.

The invention provides a controllable SCADA (supervisory control and data acquisition) industrial production control platform based on an industrial internet architecture. The controllable SCADA industrial production control platform comprises a field layer, an edge layer, a communication layer, a cloud / fog computing layer and a data management layer, wherein the field layer is composed of a sensor array, an execution mechanism, a PLC controller and an RTU terminal; the sensor array comprises a temperature sensor, a pressure sensor, a flow sensor and a position sensor, and adopts 4-20mA current loop signal output; the execution mechanism comprises an electric valve, a servo motor and a variable frequency driver, and communicates with the PLC through a Modbus RTU protocol; the PLC controller is provided with a dual-core processor and is provided with 16 digital quantity input / output channels and 8 analog quantity input channels; the RTU terminal is internally provided with a LoRa wireless communication module; the edge layer comprises an edge computing node and a protocol conversion gateway; the edge computing node is provided with an FPGA coprocessor and supports an edge reasoning framework; and multi-protocol conversion is realized through the protocol conversion gateway.

The invention discloses a control method, device and equipment for a current loop of a permanent magnet synchronous motor and a storage medium, and relates to the technical field of electric vehicle driving motors, and the control method for the current loop of the permanent magnet synchronous motor comprises the steps: obtaining an input voltage; a current loop is controlled according to a target motor mathematical model and the input voltage, the target motor mathematical model is obtained by adjusting an initial model, and adjustment is based on the required torque, a rectangular axis open-loop transfer function and a zero-pole mutual elimination function. The initial model is constructed according to a target quadrature-axis voltage equation, a dynamic inductance parameter value, a locked-rotor test and a difference strategy, and the dynamic inductance parameter value and the target quadrature-axis voltage equation are at least calculated by three items of an initial quadrature-axis voltage equation, dynamic inductance, a quadrature-axis flux linkage equation and a back electromotive force-flux linkage relation. According to the invention, the control precision, efficiency and response speed of the permanent magnet synchronous motor are improved, and the robustness of the system is enhanced.

The invention relates to the technical field of motor control, in particular to a control and parameter intelligent optimization method for an anti-impact high-precision PMSM (permanent magnet synchronous motor) feeding servo system, which comprises the following steps of: S1, establishing a physical structure and a dynamic model of a PMSM driving feeding system; s2, designing a variable gain fractional order super-spiral sliding mode controller VGFSTSMC, realizing finite time convergence of position tracking errors by dynamically adjusting and controlling gain coefficients, and inhibiting system jitter; s3, designing an adaptive sliding mode disturbance observer ASMDO, and estimating and compensating unknown disturbance in real time through adaptive gain adjustment and an integral sliding mode surface; s4, identifying a system Stribeck friction model based on a least square method, and inputting the system Stribeck friction model as a friction feedforward compensation FFC to a current loop to reduce the disturbance uncertainty of the system; s5, dynamically adjusting and optimizing control parameters of the VGFSTSMC and the ASMDO by adopting an optimization algorithm so as to minimize a root-mean-square value RMSE of a position tracking error and a maximum instantaneous error; and S6, VGFSTSMC, ASMDO and FFC are combined with an optimization algorithm, and the PMSM is driven to realize high-precision position control.

The invention relates to the technical field of servo control, in particular to a high-precision current closed-loop control system and method for a servo driver, and the method comprises the steps: collecting three-phase current, rotor position, winding temperature and bus voltage, and constructing a state data set; constructing a parameter identification model fusing physical prior and an attention mechanism, deducing inductance and flux linkage parameters influenced by temperature, saturation and cross coupling, and correcting a motor model in real time; the correction parameters are injected into an FOC decoupling and feedforward link, and a self-adaptive PI regulator is linked to set the gain of a current loop on line; calculating a d-q axis voltage command according to the update model to respectively control excitation and torque components; an extended state observer is introduced to estimate load abrupt change and parameter disturbance, feed-forward compensation is carried out, and three-phase PWM is generated through anti-Parker and SVPWM; and an inverter nonlinear compensation model of a dead zone and switch delay is constructed, PWM is pre-distorted and output to a power device, and robust and low-ripple current closed-loop control of the servo motor is realized.

The present application relates to the technical field of micro inverters, and relates to a circuit topology of a micro inverter, and a control method. One specific implementation of the method comprises: measuring the maximum power value of a photovoltaic module, and receiving a current input by the photovoltaic module; acquiring a power grid voltage value in an alternating-current power grid, determining, on the basis of the power grid voltage value and the maximum power value of the photovoltaic module, a sine wave period corresponding to an output current, and on the basis of the sine wave period, controlling on and off of a plurality of switch transistors in a resonance circuit and a voltage doubling rectifying circuit in the micro inverter, so as to respectively form a conduction current loop in the resonance circuit and form an induction current loop in the voltage doubling rectifying circuit; and transmitting the sinusoidal output current to the alternating current power grid by means of the output end of the voltage doubling rectifying circuit. The implementation implements a control strategy for first-stage power conversion of the micro inverter, improves the efficiency of the micro inverter, increases the power of the micro inverter, and reduces the cost of the micro inverter.

Some aspects of the present disclosure provide a harmonic reduce control system for controlling an inverter, including a phase-locked loop controller, a voltage sum loop controller, a repeative controller, a current loop controller, and a harmonic obtaining module. The harmonic obtaining module detects a harmonic value of a load current. The control system generates an inverter current reference value based on a first current value output by the voltage sum loop controller and the harmonic value, calculates a real-time frequency value based on a voltage of the power grid, obtains, through calculation, a repeative controller output value based on the inverter current reference value, the inverter output current, and the real-time frequency value, and outputs a first duty cycle based on the repeative controller output value. The control system limits the inverter output current based on the first duty cycle.

The invention discloses a permanent magnet synchronous motor current dynamic coupling correction method, which comprises the following steps of collecting motor three-phase stator current, performing Clark transformation to obtain a current value under an alpha-beta static coordinate system, and meanwhile, collecting through a position sensor to obtain an electrical angle true value; performing low-pass filtering calculation on the current value under the alpha-beta static coordinate system to obtain a filtering current value, and performing operation through a sliding-mode observer and a PLL phase-locked loop to obtain an electrical angle observation value; calculating to obtain a compensation adjustment coefficient according to the true value and the observed value of the electrical angle, and further calculating to obtain a current value after phase offset compensation; and performing complementary filtering calculation on the filtering current value and the current value after phase offset compensation to obtain a coupling correction current value for current loop calculation, inputting the coupling correction current value into a motor control current loop PID algorithm, and generating a PWM driving signal to drive a motor in combination with vector control. According to the method, the problems of high-frequency interference and phase deviation of current sampling can be solved, so that the motor control efficiency and the dynamic performance are improved.

The invention discloses a hierarchical cooperative control method for a cascaded H-bridge frequency converter, and the method comprises the steps: distributing a disturbance signal following a spiral phase coding rule for each H-bridge unit, and enabling the vector sum of the phase of the group of signals to generate a plurality of energy quasi-zero moments in a preset disturbance period through design; at the quasi-zero moment when the energy is greatly suppressed, synchronously triggering all units to perform high signal-to-noise ratio data acquisition, and accurately identifying transient parameters representing dynamic characteristics of each unit based on the acquired data; and finally, performing closed-loop adjustment on an upper-layer power distribution strategy, a bottom-layer current loop and the like according to the identified transient parameters so as to compensate the dynamic response difference of each unit. According to the method, high-precision online parameter identification can be realized on the premise of not influencing stable operation of the system, and the power balance capability and transient stability of the system are remarkably improved.

The invention provides a direct-current electric energy meter self-calibration method and system. The method comprises the following steps: acquiring an internal high-precision low-temperature drift voltage reference signal; converting the voltage reference signal into an analog calibration voltage signal on a sampling resistor by controlling a direct current standard voltage generation circuit according to the voltage reference signal; converting the voltage reference signal into an analog calibration current signal in a current loop by controlling a DC voltage-current conversion circuit according to the voltage reference signal; obtaining a current environment temperature, and calculating a calibration gain at the current temperature according to a preset temperature coefficient; according to a theoretical calibration value, calculating a voltage gain, a current gain and a power gain of the sampling voltage value and the sampling current value, and writing the gains into a memory; and correcting the reference voltage signal according to the obtained temperature calibration gain, and performing temperature compensation.

The invention discloses an anti-interference resistance detection circuit board and system based on four-wire system measurement, and relates to the technical field of industrial automatic detection. Aiming at the problems of low measurement precision, weak interference resistance and limited channel expansion of a traditional two-wire system, a current loop and a voltage sampling loop which are independently and electrically isolated are adopted, and a lead resistance error is eliminated through Kelvin connection; an EMI filter, a photoelectric coupler and a double-layer shielding cable are integrated, so that the influence of electromagnetic interference and a ground loop is inhibited; a single circuit board supports the parallel connection of at least two measuring units, realizes the cascade connection of multiple boards by combining an EtherCAT bus, and supports 384 channels at most. The measuring error is smaller than or equal to + / -0.1%, the single-channel detection time is smaller than or equal to 10 ms, the requirements of high-density and high-beat scenes such as perovskite photovoltaic glass are met, the method is suitable for 100-100 Momega wide-range resistance measurement, the signal transmission error rate in the industrial strong electromagnetic environment is extremely low, and the detection precision and the system reliability are remarkably improved.

The invention provides a mutual inductor loop resistance dynamic compensation correction method and device, and relates to the technical field of circuit testing, and the method comprises the steps: constructing a structural feature tensor and an environmental interference tensor according to the structural parameter information and environmental parameters of a primary winding and a secondary winding; training a dynamic compensation model based on the structural feature tensor, the environmental interference tensor and historical loop resistance test data; injecting a set direct current into the primary winding, obtaining an initial voltage signal sequence at two ends of the primary winding, and constructing a test state tensor in combination with the current loop current and the real-time environment parameters; inputting the test state tensor into the dynamic compensation model, and outputting a non-target resistance compensation value at the current moment; and based on the non-target resistance compensation value, correcting an initial loop resistance value obtained by calculating the initial voltage signal sequence to obtain a compensation resistance value of the target mutual inductor loop. According to the invention, the accuracy of mutual inductance loop resistance testing can be improved.

The invention relates to the technical field of wireless communication networks, and provides a low-channel electroencephalogram amplification circuit and brain-computer interface equipment oriented to an after-ear electroencephalogram signal, and the low-channel electroencephalogram amplification circuit comprises a dry electrode sensing module which is used for collecting an electroencephalogram signal; the front active amplification module comprises an operational amplifier circuit with high input impedance; the anti-aliasing filtering module is formed by cascading a multi-order passive filtering network and an active filtering circuit, is connected with the output end of the front active amplification module and is used for filtering high-frequency interference signals; the right leg driving feedback module comprises a programmable impedance adjusting circuit and a current limiting protection circuit, the right leg driving feedback module and the front active amplification module form a closed-loop feedback loop, and the output end of the right leg driving feedback module and the human body form a current loop through a protection resistor; the analog-to-digital conversion module adopts an integrated low-power-consumption analog front-end chip; a wireless transmission module; and the power supply management module provides independent power supply for the analog front-end chip, the operational amplifier circuit and the wireless transmission module.

The invention discloses a virtual synchronous generator stability improving method and device, and the method comprises the steps: carrying out the impedance modeling of a VSG, and obtaining a VSG impedance model; generating a regulation voltage based on the variable transient virtual damping control scheme; superposing the current loop output voltage and the adjusting voltage, and applying the superposed voltage to a VSG impedance model to adjust the three-phase voltage output by the VSG; in the variable transient virtual damping control scheme, a VSG impedance model is compared with a synchronous motor operation principle according to a power system similarity principle, a transient virtual resistance is calculated by using an angular frequency change output by the VSG and a d-axis current change, and a steady-state virtual resistance and a virtual inductance are calculated by using a direct-current bus voltage fluctuation and a direct-current bus output current change of the VSG; a regulated voltage is determined using the transient virtual resistance, the steady state virtual resistance, and the virtual inductance. The stability of the virtual synchronous generator can be improved.

The invention discloses a fast transient response Buck converter based on AOT control, which is compatible with the advantages of current mode control and AOT control, and is characterized in that an error amplifier is added in a negative feedback control loop, so that the precision of output voltage is improved, a current loop is stable, and the series resistance value of an output capacitor is not specifically limited; the change rate of the switching frequency in heavy load is reduced by using the improved self-adaptive turn-on time module, and the change of the switching frequency under different load current conditions is ensured to be small. The transient enhancement module is used for judging the output voltage, it is ensured that when the load current suddenly changes, the output voltage is fast and stable, overshoot and undershoot are reduced, and therefore the overall stability and reliability are improved. The sleep detection module Sleep is used for detecting a switching tube driving signal VCOMP so as to control the Buck converter to enter a dormant state, and therefore the purposes of reducing power consumption and improving efficiency are achieved.

Disclosed in the present invention is a variable coefficient equivalent SISO model based stability analysis method for a grid-connected converter system, comprising the following steps: constructing a variable coefficient equivalent SISO model; obtaining a complex space vector open-loop transfer function on the basis of the variable coefficient equivalent SISO model; and obtaining Nyquist curves under different current loop parameters or phase-locked loop parameters on the basis of the complex space vector open-loop transfer function. If the Nyquist curves surround point (-1,0), the grid-connected converter system is stable; and if the Nyquist curves do not surround point (-1,0), the grid-connected converter system is unstable. The present invention performs small disturbance modeling on the grid-connected converter system, considers the influence of mutual coupling between the phase-locked loop and the inner current loop, and derives a variable coefficient SISO open-loop transfer function capable of characterizing an MIMO system. Compared with the technical solution in the prior art that actual working conditions are not considered, the method disclosed in the present invention can more accurately analyze the system stability of the system under variable working conditions and variable parameters.

The invention discloses a method and device for restraining shaft system torsional vibration of a net-forming type double-fed fan under the variable wind speed. The method comprises the steps that a mathematical model of the electromagnetic torque-rotating speed difference of the net-forming type double-fed fan is constructed; drawing an electromagnetic torque-rotating speed difference Bode diagram according to the mathematical model; according to the mechanical parameters of the wind turbine and the motor, the shafting natural oscillation frequency of the doubly-fed fan is calculated, and stability analysis is conducted on damping of the shafting natural oscillation frequency in combination with the Bode diagram; drawing a small-signal model block diagram according to the mathematical model; analyzing the small-signal model block diagram to obtain an analysis result that a current loop provides a coupling path for the rotating speed and the active power; according to a stability analysis result and an analysis result of the small-signal model block diagram, negative damping brought by an operation area is weakened by reducing current loop bandwidth, so that the risk of torsional vibration of the shaft system is reduced.

The invention belongs to the technical field of industrial control, and particularly relates to a brushless direct current motor high-efficiency control method and system based on an FOC algorithm, and the method comprises the steps: superposing high-frequency sine disturbance in a voltage instruction, extracting a response component, achieving the online identification of the equivalent impedance of a motor, and dynamically solving and updating the estimated values of resistance and inductance; and correcting d-axis and q-axis voltage feed-forward items in real time by using the updated parameters, and correspondingly adjusting a current loop proportion and an integral gain. The method can adapt to the time-varying characteristics of motor parameters in an industrial field, so that the accuracy of feed-forward compensation and the stability of current loop bandwidth are effectively guaranteed, and the robustness and the control precision of a control system under complicated industrial working conditions such as variable temperature and variable load are remarkably improved; and the requirements of high-end industrial equipment on high performance and high reliability of the motor driving system are met.

The invention relates to a fault current analysis method based on first-order Taylor expansion, and the method comprises the following steps: 1, determining a system control strategy which is a network construction type control strategy and comprises a power loop, a virtual impedance link and a voltage and current loop; the power loop comprises an active power control loop and a reactive power control loop; 2, constructing a differential algebraic equation set model capable of representing the dynamic state of the system; 3, according to the characteristic that the integral value does not suddenly change at the moment before and after the fault occurs, the steady state before the fault is utilized to solve and obtain an instant state variable value after the fault, and then an instant dq-axis current value after the fault and an instant current amplitude value after the fault are obtained; 4, performing first-order Taylor expansion on the constructed differential algebraic equation set at the solved post-fault instant state variable value and the dq-axis current value, and converting a nonlinear differential algebraic equation set model into a linear differential algebraic equation set; and 5, analyzing the fault current.