14 results about "Series impedance" patented technology

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.

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 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 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.

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.