868 results about "Phase angle" patented technology

The invention discloses a multi-parameter measurement system and method for a power frequency non-partial discharge test transformer, and relates to the technical field of state monitoring of high-voltage test equipment and power equipment, and the system comprises a synchronous trigger unit which is connected to a power frequency voltage signal collection end and is used for detecting a zero crossing point of a power frequency voltage signal and generating a synchronous trigger signal, a power frequency period is divided into a plurality of sub-windows with equal phase angles. According to the multi-parameter measurement system and method for the power frequency non-partial discharge test transformer, the problem of phase mismatch of a power frequency signal and a high-frequency partial discharge signal in traditional multi-parameter measurement is effectively solved through a power frequency phase locked synchronous trigger mechanism and a dynamic noise suppression technology; and the positioning precision of the partial discharge source and the insulation defect diagnosis reliability are improved. The nanosecond-level time sequence error control is realized, and the power frequency coupling interference is inhibited while the details of the high-frequency pulse are kept by combining a phase correlation dynamic filtering strategy, so that the signal-to-noise ratio of the weak discharge signal is improved.

The invention discloses a new energy station harmonic emission level evaluation method and system based on recording data, and the method comprises the steps: carrying out the wavelet threshold de-noising processing of the recording data of line current and bus voltage in a power grid, and then carrying out the Fourier analysis, and obtaining the amplitude and phase angle of each harmonic current and voltage; on the basis of the amplitude and phase angle of each harmonic current and voltage, the harmonic order to be analyzed is determined through the harmonic voltage content rate and the harmonic distortion rate, an abnormal bus is screened as a concerned bus, and suspicious harmonic source users in the power grid are identified; establishing an equivalent model of the power grid, and solving harmonic transfer impedance between each suspicious harmonic source user and the concerned bus in the equivalent model by using a blind source separation algorithm; and quantifying the harmonic responsibility of each suspicious harmonic source user to the concerned bus. According to the invention, the accuracy of harmonic evaluation and the accuracy of tracing are improved, and the improvement of the electric energy quality of a new energy station and the stable operation of a power grid are facilitated.

The invention relates to the technical field of inverter control, and discloses an inverter output power control method and device, equipment and a storage medium. The method comprises the following steps: performing power frequency fundamental wave extraction and multi-band band-pass filtering on acquired voltage and current sampling data; performing phase compensation, first coordinate transformation and positive and negative sequence decoupling operation on the filtered fundamental wave principal component data; on the basis of a synchronous phase angle and a power grid fundamental wave frequency obtained by positive and negative sequence decoupling operation, carrying out second coordinate transformation, moving average and harmonic power delay difference operation on three-phase current and voltage data of an alpha-beta coordinate system; performing multi-level power calculation, power capacity distribution, error characteristic evaluation and decoupling operation on the inversion fundamental component and the inversion harmonic component subjected to the difference operation; and performing output signal modulation on the inversion power control quantity of the decoupling operation based on the fundamental wave synchronization phase angle, and generating a power control result. According to the invention, the control performance of the inverter on the output power in actual operation is improved.

The embodiment of the invention provides a grid-connected inverter control mode switching method and device, equipment, a medium and a product, and is applied to the technical field of electrical control. The method comprises the following steps: acquiring a control mode switching signal of the grid-connected inverter, and determining a switching direction of a control mode based on the switching signal; when the switching direction indicates that the current control mode is switched from the GFL mode to the GFM mode, setting an initial value of an integrator of a power synchronization loop of the GFM mode as a phase angle value of a phase-locked loop corresponding to the GFL mode; switching the control mode from the GFL mode to the GFM mode based on a first preset path and a step-by-step switching mode; when the switching direction indicates that the current control mode is switched from the GFM mode to the GFL mode, acquiring a power steady-state output value of the GFM mode, and setting a power reference value of the GFL mode as the power steady-state output value; and switching the control mode from the GFM mode to the GFL mode based on the second preset path and the step-by-step switching mode. The technical effect of improving the control mode switching fluency is achieved.

The invention discloses a high-proportion new energy power grid island division method considering frequency constraint, and belongs to the technical field of power system stability analysis and control, and the method comprises the steps: calculating a coherence coupling matrix of a generator and a new energy station through point voltage phase angle information; constructing a homology information undirected graph and calculating a normalized Laplacian matrix; performing characteristic value analysis, and determining the number of coherent generator groups and the coordinates of the generator and the new energy station; determining the composition of a coherent generator group through inverse mapping, and obtaining a multi-type power supply grouping result; establishing a coherence grouping constraint and a frequency security constraint according to a multi-type power supply grouping result; and constructing an island division optimal section search model and solving to obtain an optimal splitting section. By the adoption of the method, coherence grouping of multiple types of power supplies is achieved, and the optimal island division scheme is obtained by constructing and solving the island division optimal section search model considering the new energy supporting capacity and the frequency constraint.

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.

The invention provides a subway train traction energy efficiency optimization data transmission control method and system. The method comprises the following steps: acquiring numerical values of vibration parameters when a traction motor of a subway train runs, and segmenting the numerical values of the vibration parameters according to preset time granularity; calculating a comprehensive weight index of each time sequence unit based on the vibration amplitude, the frequency distribution and the phase angle parameter, and generating a dynamic code rate hierarchical allocation strategy in combination with the real-time state of the network transmission bandwidth and a control instruction reservation mechanism; and establishing a multi-dimensional parameter association model based on the numerical value of the vibration parameter, a dynamic code rate hierarchical allocation strategy, the real-time power state of each power electronic device, and the torque output instruction and energy recovery threshold feedback parameter, and dynamically adjusting a data transmission rule through the multi-dimensional parameter association model. According to the technical scheme provided by the invention, the accuracy of subway train traction energy efficiency optimization data transmission control is improved.

The invention provides a circulation power optimization method and system for a three-phase dual-active bridge, and relates to the field of power electronics, the method comprises the following steps: determining an optimal backflow modulation strategy set corresponding to a hybrid modulation group, the hybrid modulation group comprising triangular wave modulation, trapezoidal modulation, synchronous modulation and extended phase shift modulation, the optimal backflow modulation strategy set corresponding to the hybrid modulation group comprises modulation modes and degree-of-freedom relationships corresponding to different transmission power per unit value ranges in different voltage conversion ratio ranges; determining a degree of freedom and power relationship set corresponding to the hybrid modulation group, wherein the relationship set comprises a relationship between the degree of freedom and power of different transmission power per unit values corresponding to each mode; the phase shift angle, the primary side duty ratio and the secondary side duty ratio are determined by combining the real-time voltage conversion ratio and the real-time virtual power per unit value, operation of the three-phase dual-active bridge is controlled, and the method has the advantages of reducing complexity and improving portability and efficiency.

The invention discloses a stator winding grounding fault arc extinction method and system based on grounding transition resistance. The method comprises the following steps: S1, acquiring fundamental voltage of a neutral point and a machine end after normal operation and a grounding fault in real time; s2, calculating a fault phase potential EA1, and calculating a phase angle delta between the fault phase potential EA1 and the neutral point ground voltage UN1; s3, constructing a generator stator winding grounding fundamental wave fault analysis positioning equation, and substituting the measurement and calculation amount to complete fundamental wave fault positioning; s4, if multiple solutions occur in fundamental wave fault positioning, introducing a low-frequency injection quantity check criterion, and screening out a unique correct transition resistance value; and S5, carrying out arc extinction on the fault point of the neutral point of the generator in a high-resistance grounding mode. According to the method, the accuracy and reliability of fault positioning are remarkably improved, the possibility of misjudgment is eliminated, and an accurate compensation basis is provided for arc extinction.

The invention provides an electric energy meter correction electric quantity calculation method and device, electronic equipment and a storage medium. The method comprises the steps of obtaining metering historical data of a target electric energy meter; analyzing the metering historical data by adopting a phase angle feature portrait algorithm, and identifying a wiring error type corresponding to the target electric energy meter; determining a corresponding correction transformation matrix based on the wiring error type; and calculating the corrected electric quantity of the target electric energy meter based on the corrected transformation matrix. The invention provides a novel calculation scheme for the corrected electric quantity of the electric energy meter, the corrected electric quantity of the electric energy meter is calculated more accurately by adopting an advanced algorithm and a mathematical model, the interference of human factors is reduced, various complex wiring error conditions can be adapted, and the calculation efficiency is improved. Therefore, the accuracy and reliability of the correction electric quantity calculation method of the electric energy meter of the power system are improved.

Disclosed is a direct control method and system for an internal potential of a bridge arm of a new energy grid-tied inverter (GTI), the control method including the following steps. Measured values are obtained by measuring a port voltage and a port current of a GTI, instantaneous active and reactive power values are calculated, and a phase angle and amplitude reference of an internal potential of a bridge arm are obtained to generate reference values thereof. The internal potential of the bridge arm is estimated, and an estimated value used as a feedback signal, after being compared with the reference values, is sent to an internal potential controller to obtain a modulating signal, which is sent to a pulse width modulation (PWM) module, realizing direct control of the internal potential of the bridge arm. In the present disclosure, the dynamic performance of the GTI is improved while improving power quality.

The invention relates to the technical field of copper rod detection, in particular to a copper rod grain size detection method and system based on double-frequency eddy current analysis, and the method comprises the steps: synchronously obtaining a high-frequency eddy current response signal and a low-frequency eddy current response signal of the surface of a moving copper rod according to an orthogonally arranged double-frequency eddy current probe, and collecting the moving speed of the copper rod in real time; performing phase demodulation on the high-frequency eddy current response signal and the low-frequency eddy current response signal to respectively obtain a first phase angle and a second phase angle; calculating an instantaneous difference value between the first phase angle and the second phase angle, and generating an original phase difference characteristic quantity; performing dynamic compensation on the original phase difference characteristic quantity based on the movement speed of the copper rod to generate a speed compensation phase difference characteristic quantity; and inputting the speed compensation phase difference characteristic quantity into a pre-calibrated grain size mapping relation model to obtain a real-time grain size grade value. According to the invention, eddy current response interference caused by speed change in the continuous movement process of the copper rod is effectively eliminated, and high-precision detection of the grain size grade is realized.

The invention belongs to the technical field of power electronics of power supply or power distribution, and provides a control method of a three-phase four-wire inverter, a controller and an inversion control system. A first control component is generated by using a phase angle, an inversion side three-phase current sampling value and a proportional integral compensator; a second control component and a third control component are generated by using a power grid voltage angular frequency, a neutral line current sampling value, a repetitive controller and a proportional resonance controller, the three control components are combined to control an inverter power switch tube, a proportional integral compensator is still adopted, the algorithm is simple, parameters are easy to design, and the reliability is high. And meanwhile, a repetitive-proportional resonance (RC-PR) composite controller is utilized to realize suppression of neutral line fundamental wave and harmonic current, and the method has faster dynamic response to load abrupt change, so that optimization of dynamic performance and steady-state performance is realized.

The invention discloses a lightning arrester on-line monitoring method and device, and relates to the field of intelligent monitoring, and the method comprises the steps: firstly collecting original current and voltage waveform data, carrying out the frequency domain decomposition operation, then introducing an intelligent prediction mechanism, carrying out the intelligent prediction of a phase error based on the fundamental voltage phase, temperature change and harmonic characteristics, and finally, carrying out the calculation of the phase error. And performing phase angle correction operation and preliminary calculation of resistive current on the fundamental current and voltage by using the corrected phase information, and introducing a historical data smoothing algorithm to perform noise reduction optimization on a result. And finally, comparing the analyzed and processed resistive current with a preset threshold value, and judging whether an alarm prompt is generated or not. Therefore, real-time evaluation and abnormal alarm of the operation state of the lightning arrester are realized, so that a powerful guarantee is provided for safe operation of a power system.

The invention belongs to the technical field of mutual inductor verification, and particularly relates to a data processing method for testing a current mutual inductor, so as to solve the technical problem that an existing verification method cannot truly reflect the comprehensive error of the mutual inductor, and the method comprises the following steps: S1, obtaining the current waveform data of a tested current mutual inductor; s2, deducting the exponential decay aperiodic component from the original current waveform data to obtain corrected current waveform data; s3, reconstructing to obtain de-noised current waveform data; s4, acquiring fundamental waves of the primary side current and the secondary side current and setting amplitude and phase angles of subharmonics; s5, calculating an initial ratio error and an initial angle error of the current transformer; s6, generating a ratio error compensation vector and an angular difference compensation vector; and S7, respectively carrying out vector summation on the initial ratio error and the initial angle error with the ratio error compensation vector and the angle error compensation vector to obtain the final ratio error and the final angle error of the current transformer. And the test accuracy and reliability of the ratio difference and the angle difference of the current transformer are improved.

The invention relates to a power electronic technology, and aims to provide a network construction type SVG control method suitable for multiple power grid strengths. Comprising the following steps: obtaining a power grid angular frequency based on a phase-locked loop principle, and obtaining an internal frequency of SVG equipment based on capacitor voltage-frequency droop control; multiplying the two angular frequency values by respective corresponding power grid intensity adaptation parameters to obtain a phase-locked loop reference angular frequency and a droop reference angular frequency, and performing integral calculation on the phase-locked loop reference angular frequency and the droop reference angular frequency and a power grid nominal angular frequency to obtain a phase angle; and finally, a switching signal is generated in an SVG control link, so that control of SVG equipment is realized. According to the method, a more stable reference power grid phase angle is obtained, the broadband oscillation instability condition possibly occurring under a strong power grid can be suppressed, the network-forming SVG can work under different power grid intensities, and the operation stability is improved; the method can enhance the power grid synchronization stability of the network construction type control under the strong power grid, and is suitable for different system conditions.

The invention relates to the technical field of power system protection, relates to a micro-grid protection method based on measured impedance amplitude-phase variation, and provides a protection method based on measured impedance amplitude-phase variation for the protection problem of a micro-grid containing an inverter distributed power supply (IIDG). According to the method, voltage and current measured values at the two ends of a protection circuit in the micro-grid are collected in real time, a criterion is started by using voltage drop and phase current abrupt change to judge a fault, and a criterion of a measured impedance module value is adjusted by combining a zero-sequence current detection result. And when a module value criterion is met, further determining a fault section by adopting a phase angle criterion. And if the communication fails or the data is lost, self-adaptive over-current backup protection or zero-sequence current measurement is started to carry out fault positioning. The method can adapt to the grid-connected operation mode and the off-grid operation mode of the micro-grid, the fault type and the fault section are accurately judged, safe and stable operation of the micro-grid is ensured, protection sensitivity and selectivity are improved, and the method has important practical application value.

The invention belongs to the technical field of power system measurement, and relates to a three-phase power parameter wireless synchronous measurement and vector analysis method and system, and the method comprises the following steps: generating and broadcasting a synchronous pulse code containing triggering phase information; generating a predicted phase angle; obtaining a comprehensive phase deviation value; performing dynamic feature separation processing on the comprehensive phase deviation value to generate a slowly-varying propagation delay feature and a transient prediction error feature; injecting the prediction error characteristics into a local phase predictor for calibration; acquiring phase voltage / current data based on the compensated sampling time, and calculating a fundamental wave effective value and a phase angle relative to a local calibration time reference; and packaging the fundamental wave effective value, the phase angle and the local timestamp into a simplified data packet and transmitting the simplified data packet to an analysis terminal. According to the method, the problems that in a traditional mode, satellite time service rejects signals in a substation indoor or underground scene, and synchronization interruption is easily caused by electromagnetic interference are solved.

The invention provides a modulation and control method of a bridge arm multiplexing type FSBB-CLLLC bidirectional converter, belongs to the technical field of power electronics, and solves the problems that the modulation method of the bridge arm multiplexing type FSBB-CLLLC converter is not clear, the working principle is not clear, and the efficiency is reduced due to the fact that soft switching implementation is complex. The main circuit topology is divided into different bridge arms; different working modes of the converter during forward and reverse operation are researched by combining a bridge arm phase shift angle and a duty ratio; researching and solving the relationship between the inductive current and the phase shift angle of the converter by combining a modulation method and a soft switching condition, and establishing a three-dimensional table; according to different input and output voltage requirements, the duty ratio is determined, the optimal phase shift angle is determined after table look-up, and full-switching tube soft switching of the FSBB-CLLLC converter under voltage stabilization control is achieved.

The invention relates to the technical field of cable fault monitoring, in particular to a power cable fault monitoring method and system based on big data, and the method comprises the following steps: carrying out the optimization and integration of spatial layout and sampling time based on a cable monitoring node, recognizing a data segment with the reverse trend of a current peak and a voltage phase angle, and carrying out the recognition of a current peak; and further analyzing the synchronism of the current-carrying density and the temperature, extracting a periodic intersection distribution characteristic, screening a continuously progressive trend track, and forming a trend directivity factor. According to the method, the linkage accuracy among multi-point signals is guaranteed by combining synchronous acquisition of node data with time sequence calibration, the trend discrimination method performs step-by-step screening for collaborative fluctuations of different characteristic parameters, and a continuous evolution sequence of various types of tiny disturbances under a complex working condition is dynamically extracted; a temperature and current-carrying density correlation mode is adopted to highlight the progressiveness and the positioning capability of a fault precursor, and dynamic risk signals which are difficult to identify at the initial stage of change are effectively captured.

The invention relates to the technical field of power supplies, and discloses a distributed phase modifier configuration method and device based on a voltage stiffness index, which are applied to a new energy field station comprising a plurality of input branches, and the method comprises the following steps: determining respective target voltage stiffness of each input branch, the voltage stiffness being used for representing a voltage support degree; determining the target capacity and the target number of the distributed phase modifier arranged in each input branch according to the target voltage stiffness, and obtaining the station capacity and the station number according to the sum of the target capacity and the target number of each input branch; and configuring the distributed phase modifier of the new energy station based on the station capacity and the station number so as to configure the distributed phase modifier according to the target voltage support degree. According to the method, the problems that the actual supporting effect of the distributed phase modifier cannot be accurately evaluated and the distributed phase modifier configuration number and capacity better matched with the actual demand cannot be obtained due to the fact that an existing distributed phase modifier configuration technology and index lack phase angle information are solved.

The invention discloses a dual active bridge converter and a DC bias suppression method thereof, and belongs to the technical field of power electronic converters, and the method comprises the steps: carrying out the bilateral single-phase shift modulation according to a distribution coefficient p when the dual active bridge converter operates in a steady state; establishing an inductive current function model of the dual-active bridge converter considering the high-frequency link resistance; when a phase shift angle between the primary side and the secondary side of the dual-active bridge converter changes, according to circuit parameters of the dual-active bridge converter, an inductive current function model and a phase shift ratio before and after the change, a transient phase shift ratio is calculated and allocated to the primary side and the secondary side for bilateral single phase shift modulation. By introducing the transient phase shift ratio and the distribution coefficient and combining a bilateral phase shift control mode, transient direct current bias generated by transient inductive current and converter magnetic flux can be eliminated, excessive design of a magnetic element is avoided, and the ratio of any high-frequency link resistance value to a shift term can reach a stable state within a switching period.

A multiport current sensor is disclosed for measuring current. The sensor may include multiple CT or Rogowski coil segments or sections arranged in a closed loop configuration around a monitored phase line or other electrical conductor. An adjacent phase rejection circuit compares the magnitudes and / or phase angles of the voltage signals from the multiple coil segments. The adjacent phase rejection circuit may detect if a fault in an adjacent phase line or other electrical conductor is affecting the output signal of the current sensor by more than a threshold amount. The adjacent phase rejection circuit may additionally or alternatively indicate whether the measured values are valid for detecting a fault on the monitored phase line or other electrical conductor.

The invention provides a power system stability analysis method based on impedance measurement data. The method comprises the following steps: determining that a current analysis working condition is a working condition in which a disturbance voltage source is connected in series or a disturbance current source is connected in parallel in an equivalent circuit diagram corresponding to a converter topological structure diagram; under the current analysis working condition, acquiring a disturbance voltage component and a disturbance current component generated at the converter side so as to obtain converter impedance measurement data carrying amplitudes and phase angles at a plurality of frequency points, and acquiring a disturbance voltage component and a disturbance current component generated at the power grid side so as to obtain the impedance measurement data; obtaining power grid equivalent impedance measurement data carrying amplitudes and phase angles under a plurality of frequency points; and comparing the impedance measurement data of the converter with the equivalent impedance measurement data of the power grid at the same frequency point, and judging the risk of oscillation instability of the power system according to each comparison result. Implementation of the invention aims to reduce complexity of impedance measurement operation, thereby improving analysis accuracy.

The invention relates to the technical field of micro-grids, and provides a network construction type energy storage system reconstruction method and system based on dynamic impedance matching, and the method comprises the steps: obtaining the real-time impedance and real-time reactance of an associated power grid through a high-frequency disturbance signal injection decoupling mode; meanwhile, according to the voltage phase angle and the voltage drop depth of the associated power grid, respectively obtaining a phase compensation item and a dynamic adjustment coefficient, so as to dynamically adjust the virtual impedance through the phase compensation item and the dynamic adjustment coefficient; and real-time output of the target energy storage system is regulated and controlled by combining closed-loop control of the impedance outer loop and the voltage inner loop, so that voltage offset and broadband oscillation of the associated power grid are suppressed. According to the invention, the phase compensation item obtained according to the voltage phase angle and the dynamic adjustment coefficient obtained according to the voltage drop depth are added to the calculation of the virtual impedance, and the closed-loop control of the impedance outer loop and the voltage inner loop is combined, so that transient impact suppression and oscillation suppression can be realized at the same time, the limitation of separate triggering is effectively avoided, and the reliability of the system is improved. And the power grid voltage stabilization control effect is improved.

The invention discloses a CVT internal capacitance state comprehensive evaluation method and system based on temperature compensation, and belongs to the field of capacitor voltage transformer optimization compensation, and the method comprises the following steps: S1, detecting the primary voltage amplitude and phase angle of a capacitor transformer, and obtaining the performance parameters of the capacitor transformer; s2, acquiring environment temperature information; s3, determining a mathematical relationship between the environment temperature and the performance parameters of the capacitance transformer, and calculating a temperature compensation coefficient according to the mathematical relationship and the environment temperature value; s4, compensating a primary voltage amplitude and a phase angle by using a temperature compensation coefficient; and S5, analyzing the compensated voltage amplitude and phase angle data to obtain an analysis result, and evaluating whether the internal capacitance state of the capacitance transformer is normal or not according to the analysis result. By accurately detecting the primary voltage amplitude and the phase angle of the capacitance transformer and combining environment temperature information, the method can calculate an accurate temperature compensation coefficient, so that the influence of temperature change on the performance of the CVT is effectively corrected.

The invention discloses a power maximization output-oriented multi-target double-sequence current injection method under a three-phase imbalance fault, and the method comprises the following steps: S1, obtaining a three-phase voltage # imgabs0 # and a current # imgabs1 # of a PCC point after a fault steady state, and correspondingly obtaining a positive and negative sequence voltage # imgabs2 # and a current # imgabs3 # of the PCC point under a dq coordinate system; s2, according to the # imgabs 4 # and the # imgabs 5 #, calculating to obtain positive and negative sequence voltage # imgabs 6 # and phase angle difference # imgabs 7 # of the power grid in the current fault scene; s3, according to # imgabs8 # and # imgabs9 #, finding out positive and negative sequence current reference values of a dq axis in a 3-D lookup table; and S4, generating an inverter modulation signal through positive and negative sequence separation control according to the found dq-axis positive and negative sequence current reference values.

Exemplary embodiments provide a device [e.g. a circuit, such as a control circuit] for generating a [e.g. time-variable] bias voltage VDC for an electro-optic modulator, wherein the device is configured to obtain an output power signal (I) dependent on an optical output power of the electro-optic modulator, wherein the device is designed to generate the bias voltage VDC on the basis of an amplitude ratio between the fundamental and the first harmonic of the output power signal (I) and on the basis of a phase angle of a pilot signal applied to the electro-optic modulator.

The invention discloses a three-phase-shift control method and system of a DAB converter, and relates to the technical field of converter control. Comprising the steps that a primary side voltage steady-state value, a secondary side voltage steady-state value and an expected value X * of a high-frequency transformer Tr in a target DAB converter and a sampling value X fed back by the output end of the target DAB converter are acquired; performing proportional integral on a difference value between the sampling value X and the expected value X * to obtain unit transmission power Y; determining the voltage ratio # imgabs0 # of the two sides of the inductor, and determining a first phase shift angle D1, a second phase shift angle D2 and a third phase shift angle D3 according to the unit transmission power Y and the voltage ratio # imgabs1 # of the two sides of the inductor; and performing signal modulation through the first phase shift angle D1, the second phase shift angle D2, the third phase shift angle D3 and the switching frequency fs to obtain a driving signal to control the target DAB converter. Design and implementation of a control strategy are greatly simplified, and the control method is clear in mechanism and easy to control.

The invention discloses a method and system for directly controlling the internal potential of a bridge arm of a new energy grid-connected inverter, belonging to the technical field of grid-connected inverter control. The control method comprises the following steps: obtaining measured values ​​by measuring the port voltage and current of the grid-connected inverter, and calculating instantaneous active and reactive values; obtaining the phase angle reference and amplitude reference of the internal potential of the bridge arm of the grid-connected inverter respectively, and then generating the internal potential reference of the bridge arm; at the same time, estimating the internal potential of the bridge arm of the grid-connected inverter based on the port voltage and current measured values ​​and the grid-connected inverter model by using an observer; finally, using the estimated internal potential as a feedback signal of the closed-loop feedback control of the internal potential, comparing it with the generated internal potential reference of the bridge arm, and sending it to the internal potential controller, thereby obtaining a modulation signal and sending it to the PWM module, so as to realize direct control of the internal potential of the bridge arm of the grid-connected inverter; compared with the existing control method of the grid-connected inverter, the method of the invention improves the dynamic performance of the grid-connected inverter and improves the power quality.