335 results about "Current vector" patented technology

The invention discloses a current transformer real-time state diagnosis system based on Internet of Things, which relates to the technical field of electrical equipment state diagnosis and comprises a reference construction module, a disturbance excitation module, a modeling identification module, a driving unwrapping module, a self-adaptive setting module and a closed-loop control module, in the operation process of a secondary winding loop of the current transformer, a nanosecond time synchronization reference is established, a phase reference baseline is locked, current vector trajectories are continuously collected based on the time synchronization reference and the phase reference baseline, and a discrete phase residual image is constructed. According to the method, through high-precision time synchronization, phase disturbance excitation, sparse modeling identification, driving unwrapping and self-adaptive setting control, hysteresis oscillation of the secondary circuit of the current transformer is accurately identified and suppressed, the fault diagnosis accuracy and the system stability are remarkably improved, and the limitation of a traditional method in the aspects of identification sensitivity and response capability is broken through.

The invention belongs to the field of power system relay protection, and provides a mine cable high-resistance grounding fault line selection method and system for a coal mine power grid, and the method comprises the steps: calculating the zero-sequence current vector of each line before and after a fault based on the zero-sequence current of each line before and after the fault; determining the zero-sequence current variable quantity of each line before and after the fault according to the difference value of the zero-sequence current vector of each line before and after the fault; based on the zero-sequence current variation of each line before and after the fault, performing signal detection by using an oscillator chaotic system to obtain output phase diagrams of different lines; and performing fault line selection according to the states of the output phase diagrams of different lines, and determining a fault line. According to the method, the fault line is judged according to the principle that the phase and the amplitude of the zero-sequence current variable quantity of the fault line are different from the phase of the zero-sequence current variable quantity of the non-fault line, and the zero-sequence current variable quantity of the non-fault line is the same, so that the fault line can still be judged under the condition that the three-phase load is unbalanced; and the accuracy and the universality of high-resistance grounding fault line selection are improved.

The invention relates to the technical field, in particular to a power grid overhead line traveling wave recording fusion fault positioning system, which comprises signal acquisition, traveling wave event stamp capturing, zero-sequence current data flow generation, fault triggering, zero-sequence integral comparison based on time reference to generate an activation instruction, and fault recording. The characteristic topology associates and fuses the traveling wave amplitude and the zero-sequence peak value, calculates a node attenuation rate and marks a breakpoint, and the positioning solution links a double-end timestamp and a wave velocity library according to the position of the breakpoint to output a fault coordinate. According to the invention, accurate locking of the fault moment is realized through synchronous acquisition of multi-source signals; a transient window defined by traveling wave triggering ensures complete capture of features; branch identification precision is improved through current vector fusion; parameters are automatically adjusted through dynamic wave velocity matching to improve positioning accuracy; time synchronization and wave velocity compensation eliminate the influence of line parameters.

The invention discloses a frequency conversion vector control method for a digital energy-saving pump station, which belongs to the technical field of vector control and comprises the following steps: constructing a coupling vector model, simulating the running states of a pump unit under different working conditions through a virtual test signal, and automatically correcting the coupling vector model; operating data of a pump set are collected in real time, an operating situation feature set is constructed, predictive vector control is carried out, an optimal voltage vector sequence is generated, and meanwhile load fluctuation of a pipe network is predicted; demand pre-judgment is carried out on the starting and stopping time and the action amplitude of the anti-backflow device, a bidirectional disturbance suppression mechanism is constructed, current vector parameters are pre-adjusted, and calculus correction is carried out based on deviation judgment; when multiple pumps operate in parallel, the instantaneous operation efficiency point of the pump set is calculated in real time, the efficiency change trend is predicted, a load distribution scheme is generated, the comprehensive energy efficiency is evaluated, energy efficiency self-optimization is carried out, the comprehensive energy efficiency of the system is improved, and control experience reuse is achieved.

The invention relates to the technical field of fault testing, in particular to a dry-type air-core reactor turn-to-turn short circuit monitoring method based on a magnetic field difference method. According to the method, regularization constraint is introduced in an initial baseline stage to construct a reference electromagnetic coupling matrix, a heat accumulation index is recursively analyzed based on three-phase current energy, a thermally-induced magnetic field drift model is fitted in combination with magnetic field residual errors, and combined with combined constraint of the reference electromagnetic coupling matrix and the thermal drift model, a three-phase electromagnetic coupling model is established. The normal thermally induced magnetic field drift component is dynamically stripped in real-time monitoring; and under the constraint of a reference electromagnetic coupling matrix, fitting and optimizing a current vector through weighted least square state estimation, and integrating magnetic field and current two-dimensional deviation to obtain a structure consistency deviation index for fault monitoring. According to the invention, monitoring is carried out in consideration of a linear electromagnetic transfer rule and nonlinear thermal drift compensation, a complex magnetic field environment and a variable load operation condition of the dry-type air-core reactor are adapted, and continuous and reliable monitoring guarantee is provided for long-term stable operation of equipment.

The invention relates to the technical field of power distribution network automation, and discloses an electrical variable monitoring method for ring main unit operation, which comprises the following steps: acquiring three-phase electrical variable data in response to a condition that a load current change rate exceeds a preset micro-motion excitation threshold value; calculating a reference voltage based on the circuit state equation containing the inter-phase mutual inductance coupling term; the method comprises the following steps: constructing a rotating coordinate system taking a current vector as a reference axis, performing vector decomposition on a voltage deviation vector, separating a resistive temperature drift voltage component parallel to the reference axis, and taking a nonlinear impedance voltage component perpendicular to the reference axis as a monitoring parameter to judge a contact state. According to the method, linear resistance drift caused by conductor temperature rise is effectively decoupled, baseline interference is eliminated, weak nonlinear impedance distortion characteristics caused by mechanical contact degradation can be captured, and the recognition sensitivity and accuracy of early latent faults of the ring main unit are improved.

The invention discloses a fault detection method and device for a power distribution system, and a terminal equipment storage medium, and the method comprises the steps: dividing a target power distribution system into a plurality of power distribution regions, and laying current sensors between the power distribution regions, so as to enable each current sensor to obtain a current vector and a current value at each moment; constructing a current identification matrix of the target power distribution system according to the current vectors of the current sensors; wherein each element in the current identification matrix represents the current flow direction of each power distribution area; for each current sensor, calculating a current phase vector at each moment according to a current value and a current vector at each moment and the current identification matrix; and determining a fault current sensor and a fault power distribution area according to the current phase vector at each moment, the preset difference threshold value of each current sensor and the current identification matrix. According to the invention, the fault detection efficiency and the fault detection accuracy can be improved.

The invention relates to the technical field of on-line monitoring, in particular to an insulation fault on-line monitoring method and system for a medical IT system control cabinet. The method comprises the following steps: selecting a non-integer frequency multiplication detection frequency according to equivalent ground distributed capacitance in a previous monitoring period, and superposing the non-integer frequency multiplication detection frequency with a fundamental frequency to form a composite signal injection system; collecting signals to calculate a voltage instantaneous harmonic distortion rate change gradient, and selecting a time window to split the leakage current according to the change gradient; on the basis of dispersion estimation signal-to-noise ratio weighted fusion current vectors, insulation resistance and distributed capacitance are calculated; constructing a four-dimensional original feature vector composed of the insulation parameter, the phase difference and the intermodulation component energy; constructing a diagonal weighting matrix based on the resistance-capacitance ratio and the gradient to transform a feature vector, and determining the fault attribution through the Mahalanobis distance calculation with the fault template library. According to the scheme, harmonic interference can be avoided, calculation stability can be improved, insulation instantaneous sudden change can be quickly responded, and different fault types can be accurately distinguished to guide maintenance.

The invention provides an acceptance test method and system for a substation station end. The method comprises the steps that current test data and voltage test data of a plurality of power monitoring lines marked at the station end of a substation are acquired, the current test data comprise current monitoring coefficients of the power monitoring lines, and the current monitoring coefficients are related to line average current values, current vector deviations and line monitoring current variances; the voltage test data comprises a voltage monitoring coefficient of each power monitoring line, and the voltage monitoring coefficient is related to a voltage vector deviation and a voltage average achievement deviation; and according to the current test data and the voltage test data, abnormity monitoring is carried out on each power monitoring line to obtain line abnormity classification data, then line abnormal points are positioned to obtain position data of the line abnormal points, and line abnormity early warning is issued. According to the method, the problem of low acceptance efficiency caused by difficulty in simultaneous fault positioning of a plurality of test abnormal positions in the prior art is solved.

The invention discloses a flux weakening method of a permanent magnet synchronous motor finite control set model prediction control system based on an expected fundamental wave voltage closed loop, and belongs to the technical field of permanent magnet synchronous motor speed regulation control. According to the method, the problems of voltage saturation and poor robustness of a finite control set model prediction control system in a weak magnetic region are solved. According to the method, one-step delay compensation is carried out on the stator current, the stator current predicted value predicted through delay compensation is substituted into the voltage vector model under current vector dead beat control, and the compensated voltage vector reference value can be calculated. And an expected fundamental wave voltage vector is calculated based on the compensated voltage vector reference value, and finally the expected fundamental wave voltage vector is used as feedback of closed-loop flux-weakening control, so that maximum voltage control can be realized, and voltage saturation of a flux-weakening area is avoided. The method provided by the invention has better current dynamic performance, faster acceleration time and better robustness. The method can be applied to field weakening control of the permanent magnet synchronous motor.

The invention relates to the technical field of power electronic control and new energy power generation, and discloses an energy storage type photovoltaic off-grid inverter control method and system. The method comprises the following steps: acquiring an analog voltage signal and an analog current signal, and inputting the analog voltage signal and the analog current signal into a preset adaptive filter to obtain a disturbance component sequence; calculating a disturbance current sudden change degree, and if the disturbance current sudden change degree exceeds a preset sudden change threshold, constructing a to-be-counteracted current vector; determining a target phase lead angle according to the to-be-counteracted current vector and a preset transformer phase lag model, and generating a correction time domain compensation signal; generating a comprehensive modulation signal and an inverter switching instruction sequence to drive an inverter; updating a filter coefficient based on the distortion rate and determining a compensation voltage gain; and performing closed-loop correction on the sampling trigger time sequence of the analog current signal according to the system loop transmission delay to obtain a calibration current sequence. The method can effectively overcome the phase lag of the transformer and the transmission delay of hardware, and improve the electric energy quality under the nonlinear load.

The invention discloses a dual three-phase permanent magnet synchronous motor maximum torque current ratio control method and system based on virtual signal injection, and the method comprises the steps: injecting a bipolar square wave signal into a current vector angle, and calculating the d-q axis current after the bipolar square wave signal is injected through the current vector angle of the bipolar square wave signal; the d-q axis current after the bipolar square wave signal is injected is substituted into the corrected torque equation, the positive polarity torque Tup and the negative polarity torque Tdown of the dual three-phase permanent magnet synchronous motor are calculated and are expanded according to the Taylor series, when the difference between the Tup and the Tdown expanded according to the Taylor series is equal to 0, the difference between the Tup and the Tdown passes through a PI controller and then is superposed with an initial current vector angle beta, and the initial current vector angle beta is obtained. And obtaining a current optimal current vector angle, and calculating a d-q axis reference current required by the dual three-phase permanent magnet synchronous motor. According to the invention, accurate control of the maximum torque current ratio is realized.

The invention relates to the field of intelligent medical treatment, in particular to an electrical impedance imaging method and device based on mixed excitation and a program product. Comprising the steps that an initial current vector and an initial boundary voltage vector of mixed excitation are obtained, the mixed excitation comprises L kinds of excitation, and L is a natural number larger than 1; performing weighted fusion on the L excitation initial current vectors to obtain a mixed excitation current vector, and performing weighted fusion on the L excitation initial boundary voltages to obtain a mixed excitation voltage; performing electrical impedance imaging optimization function calculation based on the mixed excitation current vector and the mixed excitation voltage to obtain conductivity change; the optimization function is used for carrying out regularization calculation on regional potential distribution and conductivity variation based on the mixed excitation current vector and the mixed excitation voltage; an electrical impedance distribution image is generated based on the conductivity change. According to the invention, the resolution of EIT imaging is improved, and the method has good clinical value.

The present invention belongs to the technical field of line loss assessment, and relates to a method for assessing line loss of power quality in a substation with incomplete measurement data. The method includes: decoupling unbalanced power; determining reactive line loss power factor, unbalanced line loss power factor and harmonic line loss power factor, and determining the expression of the fundamental positive sequence active line loss power factor of each branch; determining the substation topology matrix corresponding to the substation that needs to perform unbalanced line loss assessment; calculating the current vectors of all branches according to the substation topology matrix; based on the measurement and decomposition of the current vectors of the branches in the substation, solving the fundamental positive sequence active line loss power factor of each branch in the substation and calculating the reactive line loss power factor, unbalanced line loss power factor and harmonic line loss power factor. Based on electrical network analysis and Kirchhoff's current law, the present invention uses the measurement data of some branches to realize the calculation and evaluation of the power quality line loss power factor of all branches in the substation.

The invention relates to the technical field of power grid safety evaluation, in particular to a power system short-circuit parameter prediction method, system and device based on time-space relevance and a storage medium. A multi-dimensional state vector including a node voltage vector, a branch current vector, a short-circuit impedance matrix, spatial position information and a time feature vector is constructed, and a space-time correlation feature vector including a time-dimensional feature, a spatial-dimensional feature, a space-time coupling feature and a state feature is extracted. Wavelet transform, Fourier analysis and graph theory analysis are adopted to identify a parameter change rule and a propagation effect. A multi-level prediction model of a statistical prediction layer, a deep learning layer and a fusion layer is constructed, and comprehensive description of dynamic characteristics of short-circuit parameters is realized through spatio-temporal feature fusion. A staged training strategy is adopted, and comprises the steps of establishing a basic model through offline training, updating parameters in real time through online learning, and quantifying uncertainty through a probability prediction framework. And a prediction correction mechanism and a reliability evaluation system are established, and a complete prediction-evaluation-correction closed loop is formed.

The invention discloses a self-adaptive virtual synchronous generator control method of an energy storage converter, and relates to the technical field of self-adaptive adjustment. The method comprises the following steps: S1, generating an electrical comprehensive state set based on three-phase voltage and three-phase current of a grid-connected point; s2, constructing a bearing trigger function and evaluating to generate a bearing trigger identifier; s3, obtaining a bearing fault diagnosis result based on the constructed diagnosis sample sequence; s4, according to the bearing fault diagnosis result and the diagnosis sample sequence, an adjustment parameter set is obtained, and an adjustment instruction is issued to the virtual synchronous generator; s5, updating the virtual power angle and the frequency reference; extracting a current vector and remodeling an original voltage reference according to an admittance parameter group; adjusting a power droop target and power angle evolution of a virtual synchronous generator of the energy storage converter according to a projection active instruction and a projection reactive instruction obtained through projection operation; the self-adaptive virtual synchronous generator control method realizes self-adaptive virtual synchronous generator control which keeps voltage shaping and virtual power angle continuity under current bearing constraint.

The invention relates to a current transformer error evaluation method based on current imbalance contribution analysis, and the method comprises the following specific steps: collecting CT group data in a normal error state, and constructing CT group modeling current vector data; constructing a current transformer error state evaluation model based on an overdetermined linear equation set; solving a reference weight coefficient matrix in the current transformer error state evaluation model; constructing an error fluctuation characteristic quantity; calculating a Q statistic of the error fluctuation characteristic quantity, and solving a statistic control limit Qcl of the error fluctuation characteristic quantity Ef based on empirical estimation of confidence; judging whether the operation error abnormal condition of the mutual inductor exists in the line or not; and if it is judged that the current transformer in the line at the to-be-detected moment is abnormal, positioning of the abnormal transformer is realized based on the contribution degree of each phase of current transformer to the real-time statistical magnitude. According to the invention, accurate discrimination of the metering performance of the current transformer in operation is realized, and technical support is provided for troubleshooting, state evaluation and the like of the current transformer.

The invention discloses a generator stator winding single-phase earth fault positioning method, system and device and a medium, and the method comprises the steps: enabling three phases of a generator stator winding to be connected in series end to end to form a series loop; low-frequency voltage pulses are injected into the three-phase winding, and a fault phase is determined by comparing symmetry damage characteristics of tail-end current by adopting a tail-end current vector analysis method; injecting a low-frequency voltage pulse into the current phase winding, detecting the current difference between the head end and the tail end of each parallel branch, identifying a branch with abnormal leakage current by combining a leakage current characteristic analysis method, and determining a fault branch; establishing a high-frequency distribution parameter model, and performing high-frequency voltage pulse injection positioning for multiple times to obtain three independent high-frequency pulse positioning results; and performing weighted fusion on the three independent high-frequency pulse positioning results, and performing optimization by using an intelligent optimization algorithm to obtain an optimized single-phase earth fault position. According to the invention, the accuracy and rapidity of fault diagnosis and positioning can be improved.

The invention discloses a distributed energy storage cluster access power distribution network harmonic resonance analysis method, which comprises the following steps of: aiming at system elements in a power distribution network, respectively constructing harmonic impedance models considering d-axis and q-axis asymmetric dynamic states under a dq coordinate system; injecting a small disturbance component, constructing a small disturbance modal impedance matrix Z of the whole system based on a harmonic impedance model, and obtaining a node voltage variation matrix according to the small disturbance component and the small disturbance modal impedance matrix Z; decomposing an inverse matrix of the small disturbance modal impedance matrix into a form of multiplying a left eigenvector matrix, a diagonal eigenmatrix and a right eigenvector matrix; and substituting the decomposed small disturbance modal impedance matrix into the node voltage variation matrix to obtain a linear relationship between a modal voltage vector and a diagonal eigenmatrix and a linear relationship between the modal voltage vector and a modal current vector, and obtaining a critical modal and a corresponding resonant frequency according to an eigenvalue of the diagonal eigenmatrix.

The embodiment of the invention discloses a distribution transformer electrical parameter complex field on-line synchronous vector monitoring device and method, and the device comprises a high-precision synchronous vector measurement and collection module and a controller, and the high-precision synchronous vector measurement and collection module is connected with the controller. The high-precision synchronous vector measurement and acquisition module is used for being connected with a neutral line at the low-voltage side of the distribution transformer to be measured and a three-phase line at an outlet, and is used for measuring and synchronously acquiring a zero-sequence voltage vector and a neutral line current vector at the low-voltage side of the distribution transformer to be measured. The controller is used for determining the short-circuit complex impedance of the distribution transformer to be measured according to the zero-sequence voltage vector and the neutral current vector, so as to determine the load loss and the short-circuit voltage of the distribution transformer to be measured according to the short-circuit complex impedance, namely, the zero-sequence voltage vector and the neutral current vector are simply and synchronously measured on the low-voltage side of the distribution transformer. Therefore, on-line monitoring of short-circuit complex impedance and electrical parameters can be realized, and problems in the prior art are solved.

The invention discloses a low voltage ride through control method and device for an energy storage power station under a power grid voltage fault, and the method comprises the steps: carrying out the coordinate transformation of measured three-phase power grid voltage and power grid current, and obtaining a power grid voltage vector and a current vector under a two-phase rotation dq coordinate system; judging a power grid voltage fault state according to the obtained fault detection signal, and calculating the output power of the converter based on the power grid voltage fault state according to the voltage vector and the current vector; calculating a current reference value according to the output power, and adjusting the current reference value by using a virtual admittance current limiting method to obtain a modulation current; modulation voltage is calculated based on the modulation current, and a modulation voltage signal is converted to generate a three-phase switching signal. According to the invention, the current reference value is adjusted through the virtual admittance current limiting method, so that the energy storage converter can suppress transient current impact during the fault period.

The invention relates to the technical field of power supply load analysis, in particular to an overload monitoring method and device for an industrial mining power supply and the power supply. The method comprises the following steps: dividing according to the size of current data in each phase line in a monitoring time period to obtain a current duration section; according to the abrupt change abnormal degree of the current continuous section on each phase line circuit and the distribution size of the current data, the load abnormal degree is obtained; and analyzing the synchronous change degree of the current duration among the three-phase lines, obtaining the load abnormity synchronization degree by combining the deviation condition among the load abnormity degrees, obtaining the overload possible index of the power supply by combining the current vector sum in the monitoring time period, and obtaining an overload analysis result. The overload condition of the current power supply is determined according to the current load change condition and the synchronous load balance condition on each phase line, the overload analysis accuracy of the three-phase power supply load unbalance condition is improved, and the reliability and the control precision of a power system are further improved.

The invention provides a qualitative evaluation and error detection method and system for the out-of-tolerance state of a current transformer, and the method comprises the steps: obtaining the current signals of a group of current transformers related to the same node on a line, constructing the physical relation of the current signals, and obtaining a KCL residual data set; standardization processing is carried out, an evaluation standard model is established by adopting RPCA, and a fault current transformer and a time period in which a fault occurs are screened out; current signals of the current transformer in the time period are extracted, a node current vector and an objective function with the minimum absolute value are constructed based on KCL constraint, and an optimization model is established; and obtaining a local optimal solution according to a QPSO optimization algorithm, and continuously iterating to reach a final condition to obtain a global optimal solution, namely solving to obtain a ratio error and a phase error of the group CT. The technical problems that CT metering state evaluation is low in efficiency, high in calculation complexity, large in detection error, low in universality, incomplete in error type identification and prone to causing false alarm or missing detection of the out-of-tolerance current transformer are solved.

The invention relates to an overvoltage risk assessment method, device and equipment for non-full-phase operation of a new energy access weak power grid system. The method comprises the following steps: acquiring electrical quantity data of the new energy access weak power grid system, and a voltage source, grid-connected equivalent impedance, series equivalent impedance and non-full-phase operation line impedance of a power transmission line of the new energy access weak power grid system with a single-phase fault; calculating n positive sequence current vectors and negative sequence current vectors according to each piece of electrical quantity data; calculating n positive sequence port voltage vectors and negative sequence port voltage vectors according to the fault data, each positive sequence current vector and each negative sequence current vector; according to the positive sequence voltage component rated value, each positive sequence port voltage vector and each negative sequence port voltage vector, actual positive sequence voltage and actual negative sequence voltage are obtained through calculation; and according to the actual positive sequence voltage, the actual negative sequence voltage and the positive sequence voltage component rated value, calculating to obtain a single-phase voltage maximum value, and according to the single-phase voltage maximum value, judging whether the system has an overvoltage risk in a non-full-phase operation state.

The electromechanical coupling dynamics modeling method comprises the following steps: establishing a current vector control system model according to a permanent magnet synchronous motor structure parameter, a motor rotor displacement and a mechanical rotation angle; motor electromagnetic torque and motor unbalanced magnetic pulling force are calculated through the motor instantaneous inductance parameter and the instantaneous three-phase voltage; calculating and establishing a bearing-rotor dynamical model according to the size parameters of the propulsion shafting; and coupling the calculation equations of the motor electromagnetic torque and the motor unbalanced magnetic pulling force with the bearing-rotor dynamical model to establish a propulsion shafting electromechanical coupling dynamical model. By calculating the influence of the displacement of the permanent magnet synchronous motor rotor on the inductance and the air-gap magnetic field of the permanent magnet synchronous motor, the electromagnetic torque and the unbalanced magnetic pulling force are calculated more accurately, and the propulsion shafting dynamic response characteristic which is more practical is obtained through the propulsion shafting electromechanical coupling dynamic model.

The invention provides a deep brain stimulation method and system based on controllable current vectors of high-channel-number electrodes, and the method comprises the following steps: implanting two electrodes into a target region, and enabling a nucleus of the target region to be located between the two electrodes; by selecting different contacts on the stimulating electrodes, multiple channels of induced currents in different directions are generated in a plane constructed by the two electrodes; vector current is formed through vector superposition of the induction current of each channel, and the vector current acts on the target nuclei. The high-channel-number electrodes are adopted, programming control is carried out between the two electrodes, accurate control over current vectors is achieved, control over the magnitude and direction of target region nuclei stimulation current is accurately achieved through current vector superposition, therefore, a brain lesion area can be stimulated more accurately, meanwhile, the current vectors can be accurately controlled, and the stimulation effect of the brain lesion area is improved. And unnecessary current is prevented from diffusing to surrounding normal brain tissues, so that side effects caused by stimulation of a non-target area are reduced.

The invention discloses a current source inverter power supply permanent magnet synchronous motor system control method and system, and belongs to the field of permanent magnet synchronous motor control. Establishing a discrete state space equation of the dq-axis current source inverter power supply type permanent magnet synchronous motor system by using state variable information of a control system of the permanent magnet synchronous motor system at a sampling k moment; designing a filter capacitor voltage estimator, obtaining a filter capacitor voltage estimated value, designing a feedback-integral controller, and solving a dq-axis inverter output current control instruction; three optimal current vectors closest to an inverter output current control instruction are selected, the optimal current vectors and the optimal duty ratio are calculated, an optimal switching pulse sequence is output to act on a switching tube of the current source inverter, and current control over the current source inverter power supply permanent magnet synchronous motor system is achieved. The method is high in control precision and high in dynamic response speed.

The invention relates to a permanent magnet synchronous motor MTPA control method based on a double-virtual direct current signal injection mode, in particular to a motor control method, and particularly relates to a control method of a built-in permanent magnet synchronous motor. A pair of virtual direct-current signals with the same amplitude and opposite polarities are injected into a current vector angle beta, Taylor expansion is carried out on electromagnetic torque containing the pair of signals, subtraction is carried out on the two signals to obtain an approximate value of the torque to a first-order partial derivative of the current vector angle, and the approximate value is input into an integral regulator; when the input quantity is controlled to be 0, the optimal current vector angle beta mtpa can be obtained, and MTPA control is achieved. In order to improve the dynamic performance and the steady-state performance of control at the same time, virtual direct-current signals with different amplitudes are selected for injection under different working conditions, the motor can be made to rapidly approach the working state of the optimal current vector angle, and fluctuation of the current vector angle in the stable state is reduced.

The invention discloses a control method and system for an AC / DC access flexible interconnection device. The method comprises the following steps: judging an operation mode of a transformer area; calculating an interconnection voltage difference value and a phase angle difference value; if the voltage difference is smaller than the closed-loop voltage difference threshold value and the phase angle difference threshold value, the flexible interconnection device is switched into an interconnection operation mode; acquiring input and output voltage and current, direct current bus voltage and current and direct current leading-out bus voltage and current of the series-parallel module; converting the three-phase voltage and current measurement value into a voltage and current value under a dq coordinate system; outputting optimized voltage and current values by adopting a PSO (particle swarm optimization) algorithm; calculating a reference voltage current vector and action time, and generating switching signals of each phase; performing error calculation to obtain a voltage and current error signal value; issuing voltage and phase regulation and current regulation instructions, and dynamically regulating voltage and current signals. According to the method, the electric energy quality treatment requirements of the micro-grid in complex dynamic scenes such as high-power pulsating load and distributed power supply power fluctuation can be met.

The invention discloses a cutting machine motor intelligent temperature management method and system based on load prediction, relates to the technical field of cutting machine motor temperature management, and is used for solving the problems of temperature response lag and local overheating under the conditions of complex tracks and load fluctuation. In the operation process of the cutting machine, three-phase stator side current signals of the motor are continuously captured, a current vector input quantity is obtained through coordinate transformation and input into the sliding mode observer to estimate the rotor position and the motor rotating speed, a load trend quantity is generated, combined compensation modulation is carried out, and a compensation value is output to a power output link to dynamically adjust the duty ratio. According to path analysis, marking a hot stacking sensitive path section, calculating a power output change rate and shielding wind flow disturbance intensity, screening out a thermal response to-be-detected section, collecting data through a thermosensitive channel to construct a regional thermal risk index, executing differential air cooling adjustment and power modulation path adjustment, and recording state data in real time; and fine management of the full-working-condition temperature of the motor of the cutting machine is realized.