22 results about "Series impedance" patented technology

The invention relates to the technical field of new energy grid-connected control, in particular to a fault stage transient stability analysis method and system for a following-constructed network type converter series-parallel system, and the method comprises the steps: enabling a constructed network type converter to be equivalent to a controlled voltage source series impedance, enabling a following network type converter to be equivalent to a controlled current source, and enabling the controlled current source to be equivalent to a controlled voltage source series impedance; the whole series-parallel system is equivalent to a scene in which double voltage sources and a single current source are jointly connected in parallel to a PCC point, and a series-parallel system model is constructed; according to the series-parallel system model, respectively representing an active power coupling term of the network-building type converter and a voltage coupling term of the network-following type converter under the condition of considering parallel connection of the network-following type converter and the network-building type converter; according to the coupling term, remodeling an active loop control structure of the network-constructing converter and a phase-locked loop synchronization structure of the network-following converter, and obtaining a transient analysis model of the series-parallel system considering the coupling term; the transient stability of the hybrid system in the power grid fault stage is analyzed through the transient analysis model, and the influence on the transient stability is effectively represented.

A converter station AC filter group circuit breaker abnormal arcing modeling analysis method comprises the following steps: firstly, carrying out time mark alignment, amplitude calibration and filtering de-noising on wave recording signals such as AC bus voltage and filter branch current to obtain high-quality input data; then, combining a primary wiring diagram, enabling an alternating current system to be equivalent to an ideal power supply and series impedance, enabling circuit breaker arcing to be equivalent to arc resistance changing along with time, and constructing an equivalent circuit model comprising the power supply, the impedance, a capacitor, an electric reactor and dynamic arc resistance; establishing a state space equation according to a voltage and current constraint relation, and performing time domain solution by adopting a two-step two-order or three-order diagonal implicit Runge-Kutta method to obtain voltage and current responses of the whole process of the fault; on this basis, the arc resistance change is inversed according to the ratio of arc voltage to current, the current zero passage is identified through the resistance symbol change at adjacent moments, and the zero passage section is smoothed; and finally, the inversion result is verified again by means of the simplified equivalent model.

The invention belongs to the technical field of key power supply conversion in an aviation airborne starting power converter, and discloses a novel matrix LLC secondary side resonant topology. On the basis of an LLC resonant topology circuit, a resonant cavity is placed on the secondary side of a transformer, a matrix transformer with the primary side connected in parallel and the secondary side connected in series is adopted, and the matrix transformer comprises n parallel H-bridge inversion units on the low-voltage side, a high-frequency matrix transformer, the LLC resonant cavity on the high-voltage side and a full-bridge uncontrollable rectification circuit. The matrix transformer is composed of n transformer units, primary sides of which are connected in parallel and secondary sides of which are connected in series. A primary winding of each transformer unit is connected with the H-bridge DC-AC inverter circuit. According to the matrix LLC secondary side resonant topology, by controlling the switching frequency of the H-bridge power MOS tube, square wave signals with different frequencies are obtained, the series impedance of the resonant capacitor and the resonant inductor is changed, the partial voltage at the two ends of the excitation inductor is adjusted, gain control over the resonant cavity is achieved, and the purpose of adjusting the output load voltage is achieved.

A computer-implemented method and system includes a head-mounted wearable device having two current electrodes that delivers an input alternating current over a range of frequencies to a subject during at least one intervention. The head-mounted wearable device includes at least two sense electrodes that collect voltage difference measurements in response to the input alternating current. A measurement validation module applies a Hilbert transform or a Cramer-Kronig test to the voltage difference measurements to generate a validated time-series impedance spectrum. A head fluid dynamics module fits the validated time-series impedance spectrum to an electrical circuit model to determine a glymphatic flow response to the at least one intervention.

This invention discloses a method for calculating the steady-state voltage and circulating current of the sheath based on a distributed model of a multi-loop terrestrial cable. The method includes: 1. Obtaining the factors affecting the steady-state induced voltage and circulating current of the sheath of a multi-loop single-core terrestrial cable; 2. Establishing a distributed parameter model per unit length of the multi-loop single-core terrestrial cable, thereby obtaining the linear equation matrix describing the entire multi-loop terrestrial cable system; 3. Calculating the series impedance of the multi-loop single-core terrestrial cable lines in the system's linear equation matrix; 4. Calculating the parallel admittance between the multi-loop single-core terrestrial cable lines in the system's linear equation matrix; 5. Constructing the impedance matrix and admittance matrix to complete the system's linear equation matrix; 6. Determining the boundary conditions of the system's linear equation matrix; 7. Solving the system's linear equation matrix to obtain the values ​​of the steady-state induced voltage and circulating current; 8. Calculating the steady-state induced voltage and circulating current of the sheath of a multi-loop single-core terrestrial cable with the same arrangement. This invention eliminates repetitive modeling and simulation calculations, improves the model's adaptability, and has significant engineering value.

The present invention measures the impedance of impedance elements in a state in which a measurement target, which is formed by connecting a plurality of impedance elements in series, and a non-measurement target are connected in parallel.　The present invention comprises: a measurement current supply unit 2-1 which supplies a measurement AC current Im1 between both ends of electrochemical cells C2, C3; a measurement current supply unit 2-2 which supplies a measurement AC current Im2 between both ends of electrochemical cells C7-C10; a voltage detection unit 3-1 which detects a complex terminal voltage value V1 across the electrochemical cells C2, C3; and a processing unit 4 which calculates the impedance of the electrochemical cells C2, C3 on the basis of the complex terminal voltage value V1 detected by the voltage detection unit 3-1 and a complex current value IZ1 of an AC current Iac detected by a current sensor 7-1 in a state in which the measurement AC current Im2 and the measurement AC current Im1 flowing through a power supply device PD cancel each other.

A filter circuit, a filter and a communication device relate to the technical field of communication. The filter circuit includes a series branch connected between the first port and the second port and including a series resonance circuit and a series impedance element connected in series with each other, wherein the series resonance circuit includes a series resonator; and a parallel branch connected between a parallel node and a ground potential and including a parallel resonance circuit and a parallel impedance element connected in series with each other, wherein the parallel resonance circuit includes a parallel resonator, and the parallel node is located on a connection path of the first port and the second port; wherein the resonance frequency of the series resonator is less than the resonance frequency of the parallel resonator.

This invention relates to the field of power systems and their automation technology. It provides a method for constructing a traction network simulation model based on current distribution characteristics. The method includes: establishing multi-conductor transmission line equations based on Maxwell's equations, including Gauss's law and Faraday's law; deriving a chain-like network model of the traction network based on the multi-conductor transmission line equations and a chain circuit model with multi-conductor transmission lines as the backbone and randomly connected transverse elements; simplifying the chain-like network model to obtain a simplified series impedance matrix equation and a parallel admittance parameter matrix after conductor merging; and calculating the series impedance and parallel admittance values ​​using the simplified series impedance matrix equation and the parallel admittance parameter matrix after conductor merging. This invention improves the accuracy and applicability of traction network electrical simulation and signal analysis.

The invention belongs to the technical field of power system simulation, and discloses an interpolation-free hybrid line simulation model of accurate zero sequence impedance and a construction method thereof, the model comprises a decoupling module, a parallel compensation module and a series synthesis module; the decoupling module is used for enabling the electromagnetic propagation delay time to be equal to the simulation step length of a simulation program and realizing interpolation-free calculation decoupling at the two ends of the line; the parallel compensation module is used for compensating introduced additional parallel susceptance and inter-phase capacitance in an original physical model of the introduced line; and the series synthesis module is used for synthesizing the residual series impedance of the line, so that the total series positive-sequence impedance and zero-sequence impedance of the equivalent model are matched with a preset target value under the fundamental frequency. According to the method, calculation decoupling without interpolation can be provided for a short line, and full-sequence network parameters including zero-sequence components can be accurately simulated, so that the requirement of modern power distribution network high-fidelity parallel simulation can be well met.

The application belongs to the field of power systems and relates to a series virtual impedance method for improving grid-connected current quality of a static synchronous reactive compensator under a weak power grid. In view of the problems that the existing methods cannot simultaneously achieve stability and harmonic suppression and the THD of grid-connected current increases and the quality of grid-connected current decreases due to harmonics in a weak power grid, the application constructs a grid-connected system with a three-level diode clamped STATCOM as a core, designs a harmonic suppression module containing a multi-resonant controller and a series virtual inductor, superimposes the harmonic suppression module and an original virtual series impedance to form a composite series virtual impedance, injects the composite series virtual impedance into a shunt impedance correction feedforward path, and realizes closed-loop control of grid-connected current. The method can effectively suppress characteristic harmonics, reduce THD, ensure stable operation of the system under a weak power grid, and has good dynamic performance and is easy to implement.

The invention discloses an SVG virtual impedance adaptive switching control method and system. The method mainly comprises a virtual series impedance control link, a virtual parallel impedance control link and an SVG double-closed-loop control link. The oscillation frequency of a new energy station is monitored through VMD and HT conversion, an optimal virtual impedance control loop is put into use, and the output of a virtual impedance control link is used as a compensation amount to be compensated to an original double-closed-loop control structure of the SVG, so that the SVG obtains a more excellent oscillation suppression effect in a broadband range. And the limitation that a single virtual impedance control method is difficult to adapt to the multi-band oscillation suppression requirement is overcome. The method can be widely applied to wind power, photovoltaic and other new energy grid-connected systems containing the SVG, and an effective solution is provided for broadband oscillation suppression and safe and stable operation of the new energy grid-connected systems.

The invention relates to a plasma radio frequency power source and a radio frequency system. The plasma radio frequency power source comprises a radio frequency power amplifier module; the impedance compression unit comprises at least one impedance compression network, and the impedance compression network is provided with a series branch circuit or a parallel branch circuit, or both of the series branch circuit and the parallel branch circuit. The radio frequency power amplifier module, the matcher and the impedance compression unit are sequentially connected in series, the output end of the impedance compression unit is used as a load cavity connecting port, and the impedance compression unit is used for compressing impedance of a load cavity to be within a matchable impedance range of the matcher. According to the invention, the impedance compression unit is arranged between the matcher and the cavity, so that different and large-range changing load impedances of a plurality of cavities can be compressed to a narrow range, the design requirement on the matcher is reduced, and the requirements on larger-range impedance matching capability and higher matching speed of a radio frequency system in different processes can be met; and the product cost is reduced and the product structure is miniaturized.

The application discloses an SVG virtual impedance adaptive switching control method and system, mainly including a virtual series impedance control link, a virtual parallel impedance control link and an SVG double closed loop control link; the oscillation frequency of a new energy station is monitored through VMD and HT transformation, the optimal virtual impedance control loop is put into operation, and the output of the virtual impedance control link is compensated to the original double closed loop control structure of the SVG as a compensation amount, so that the SVG obtains more superior oscillation suppression effect in a wide frequency range, and the limitation that a single virtual impedance control method is difficult to adapt to multi-frequency band oscillation suppression demand is overcome. The application can be widely applied to wind power, photovoltaic and other new energy grid-connected systems containing SVG, and provides an effective solution for wide frequency oscillation suppression and safe and stable operation of the new energy grid-connected systems.

This invention relates to the field of startup surge suppression technology. Specifically, it relates to a low-loss startup surge suppression method. The method includes the following steps: S1, collecting the equipment load status and current-limiting device temperature before startup, and simultaneously acquiring historical startup data of the electrical equipment. Based on the equipment load status and the current-limiting device temperature, the historical startup data is classified into different status types. This invention uses a dual-loop architecture of current-limiting circuit and bypass circuit. Immediately after startup, the main circuit is switched to the pure copper bypass circuit, and the current-limiting circuit completely exits operation. There is no additional power loss caused by any series impedance, completely solving the problem of continuous heating and low energy efficiency caused by long-term series connection of traditional current-limiting components. Simultaneously, a standard startup current curve is generated based on historical successful startup data to accurately locate the optimal switching time and minimize the operating time of the current-limiting circuit.

The invention discloses a self-adaptive series impedance compensation method considering bidirectional power flow characteristics, which belongs to the technical field of power distribution network voltage control, and comprises the following steps: acquiring a voltage signal and a current signal of a common connection point in a line in real time, and calculating active power and reactive power of the line; according to the active power and the reactive power, virtual impedance compensation quantity needing to be connected in series is calculated; judging the power flow direction according to the flow direction of the active power, and determining the positive and negative polarities of the virtual impedance compensation amount according to the power flow direction; and determining a drop voltage based on the virtual impedance compensation amount, and performing voltage compensation. According to the method, the problem of bidirectional out-of-limit of the steady-state voltage caused by reverse power transmission of the distributed power supply is solved, and the accuracy and stability of the terminal voltage of the power distribution network are ensured.

A computer-implemented method and system includes a head-mounted wearable device with two current electrodes that provide input alternating currents over a range of frequencies to a subject during at least one intervention. The head-mounted wearable device includes at least two sense electrodes that collect voltage difference measurements in response to the input alternating currents. A measurement validation module applies a Hilbert transform or a Kramer-Kronig test to the voltage difference measurements to generate validated time-series impedance spectra. A cranial fluid dynamics module fits the validated time-series impedance spectra to an electrical circuit model to determine a glymphatic flow response to the at least one intervention.

The application discloses a kind of active capacitances based on full-bridge inverter, the active capacitance includes series impedance network, full-bridge inverter and control circuit;The series impedance network includes series inductance and series capacitance, and the series inductance is connected in series with series capacitance;The full-bridge inverter includes first bridge arm, second bridge arm and DC voltage source, and the first bridge arm and second bridge arm are powered by DC voltage source, and the switching node of the first bridge arm is connected to the switching node of second bridge arm both ends of series impedance network;The control circuit samples active capacitance both ends voltage and active capacitance input current in real time, and the output voltage of full-bridge inverter is controlled by closed loop control algorithm to control first bridge arm and second bridge arm, so as to adjust the input current of active capacitance, reach the purpose of adjusting the capacitance value of active capacitance.The application greatly improves the performance of variable capacitor, reduces the cost and volume of variable capacitor.

This invention discloses a practical method for calculating short-circuit current in power systems considering the impact of photovoltaic (PV) power plants. The method includes: performing short-circuit fault analysis on the PV power plant; calculating the PV grid-connected node voltage based on the short-circuit current output by the PV power plant under different scenarios; calculating the mean PV grid-connected node voltage as an estimated value of the grid-connected point voltage after the fault; calculating the equivalent impedance value in the Thevenin equivalent model based on the estimated voltage of the grid-connected point after the fault; connecting the PV fault equivalent branch at the PV power plant grid-connected point in the positive-sequence network of the system; and obtaining the short-circuit current distribution of the entire network using short-circuit fault calculation. The practical method for calculating short-circuit current in power systems provided by this invention does not require detailed model parameters of the PV power plant. It uses a constant potential source series impedance branch to characterize the impact of PV power plant grid connection on the system short-circuit current, avoiding the iterative calculation process in the theoretical solution of short-circuit current. It offers fast calculation speed, strong feasibility, and no convergence issues.

The invention relates to the technical field of magnetic element measurement, in particular to an impedance measurement method for common-mode inductors under direct-current bias, and the method comprises a differential-mode impedance measurement mode and a common-mode impedance measurement mode, the differential-mode impedance measurement mode comprises the following steps: one ends of two common-mode inductors with consistent structural parameters are short-circuited, and the other ends of the two common-mode inductors are short-circuited; the other ends of the two parallel branches are respectively connected into the two parallel branches; in a parallel branch, an impedance analyzer, an isolation capacitor and an alternating current isolation inductor are sequentially connected in series and then are connected to the positive electrode of a direct current bias source; in the other parallel branch, an isolation capacitor is connected in series and then is connected to the negative electrode of the direct current bias source to form a closed loop; bias current is applied through a direct-current bias source, so that the two common-mode inductors are in a direct-current magnetic bias state; and applying an alternating-current measurement signal through the impedance analyzer, and collecting measurement data to obtain the differential-mode impedance of the common-mode inductor under the direct-current bias. Therefore, the problems of measurement distortion, insufficient anti-interference capability, insufficient equipment protection and the like in the prior art are solved.

This application relates to a method, apparatus, and computer device for analyzing current-carrying imbalance limitation information. The method includes: obtaining the actual impedance parameters of parallel cables in the same direction; constructing and adjusting an optimized cable imbalance model based on the actual impedance parameters using a dynamic programming algorithm; identifying the target cable series impedance value; calculating the current-carrying imbalance based on the target cable series impedance value; adjusting the target cable series impedance value using a preset adjustment strategy; returning to the above steps to obtain the current-carrying imbalance corresponding to each target cable series impedance value, thereby identifying the current-carrying imbalance limitation information and the actual impedance parameters; and then iteratively returning to the above steps to obtain the current-carrying imbalance limitation information of the parallel cables in the same direction. This method can improve the accuracy of current-carrying imbalance limitation analysis of laid cables.

The invention discloses a dentin caries depth electrical impedance detection method and system, and belongs to the technical field of nondestructive detection of oral diseases, and the method comprises four steps of multi-frequency impedance spectrum acquisition, impedance spectrum feature extraction, equivalent circuit model fitting and caries depth inversion. The physical property that different levels of dentin cause different conductivity due to mineralization degree difference is utilized, quantitative detection of the caries depth is realized by establishing a three-layer series impedance equivalent circuit model and nonlinear fitting inversion, the influence of the environment temperature is eliminated by adopting a temperature compensation algorithm, and the detection precision reaches 0.2 mm.

This invention relates to the field of intelligent sensor technology, specifically disclosing a method for calibrating IGBT driver parameters based on intelligent sensors, comprising the following steps: S1, acquiring IGBT driver nodes; S2, generating a composite disturbance current command and injecting it into the IGBT driver nodes to acquire voltage response waveforms and current disturbance waveforms; S3, generating a disturbance admittance spectrum based on the voltage response waveforms and current disturbance waveforms; S4, calculating the equivalent series impedance and correcting the disturbance admittance spectrum to obtain the target spectrum; S5, fitting the target spectrum to an equivalent circuit model to extract the equivalent parameter vectors of the corresponding IGBT driver nodes; S6, calculating the parameter distance between the equivalent parameter vectors of different IGBT driver nodes on the same feeder branch, and performing collaborative calibration on all IGBT drivers on the branch when the parameter distance exceeds a set threshold. This invention can enhance the system's adaptability to parameter drift and environmental changes during long-term operation.