322 results about "Transient current" patented technology

Embodiments of the present invention provide a method and apparatus for suppressing transient current of a grid-forming converter, a computing device, a computer-readable storage medium, and a computer program product. The suppressing method comprises: calculating first virtual impedance on the basis of an actual voltage instantaneous value of a point of common coupling; calculating second virtual impedance on the basis of an actual current maximum amplitude of the point of common coupling; and suppressing the transient current of the grid-forming converter on the basis of the first virtual impedance and the second virtual impedance. In this way, by combining the actual voltage instantaneous value of the point of common coupling and the actual current maximum amplitude of the point of common coupling, transient current can be suppressed at the moment when a fault occurs in a grid-forming converter, thereby avoiding misoperation triggering of a protection apparatus, and ensuring that the grid-forming converter can restore stable operation once the fault is removed.

The invention belongs to the technical field of fault early warning, and discloses a heater fault early warning method and system based on current analysis. Comprising the steps that transient current signals of all heating wire loops in the copper bush heater are collected in real time, harmonic characteristic parameters are extracted, and a dynamic current fingerprint database and a multi-dimensional harmonic characteristic spectrum are generated respectively; dynamically calculating the contact impedance between each heating wire and the copper sleeve groove according to the dynamic current fingerprint database and the multi-dimensional harmonic characteristic spectrum; the current distribution path of each heating wire in the copper sleeve groove is restored in real time, the abnormal contact form of each heating wire is identified, the falling risk probability and falling risk strength of each heating wire are dynamically predicted by fusing the falling precursor signals of each heating wire detected in real time, and a grading early warning strategy report is generated in real time; according to the invention, fault early warning can be converted into preventive maintenance from post-maintenance, the intelligent level of operation and maintenance of the heater is improved, and the continuity and safety of production are guaranteed.

The invention relates to the technical field of data processing, and provides a battery performance detection device and method, and the method comprises the steps: obtaining transient voltage data and transient current data of a battery in different working states, carrying out the wavelet decomposition of the transient voltage data, obtaining a multi-state voltage feature, carrying out the time sequence mapping of the multi-state voltage feature and the transient current data, and obtaining a multi-state voltage feature; and obtaining an inflection point parameter set to construct a parameter stability matrix, analyzing a battery health state based on the parameter stability matrix, generating a battery life prediction based on a health state index, and performing trend analysis and residual life estimation to generate a battery performance detection result. When a complex electrochemical environment and various working states are processed, the efficiency and accuracy of battery performance detection are improved, and the problems of long battery test period and poor detection precision in practical application are solved.

The invention relates to the technical field of printed circuit board signal management, and discloses an intelligent management method and system for a printed circuit board signal control process, and the method comprises the steps: obtaining the noise data of a target channel of a target management object and all adjacent channels in real time, analyzing the noise data of all channels, generating a frequency domain collaborative management domain, and carrying out the frequency domain collaborative management domain; the target management object is a server printed circuit board; the method comprises the following steps: S1, analyzing noise data to generate a frequency domain collaborative management domain, S2, mapping transient current into an N * N matrix and establishing a two-layer graph convolutional network, and S4, acquiring load data in a 100ms window, processing by using a two-way long-short-term memory network of two hidden layers, and adapting to signal transmission of a server printed circuit board, so as to avoid misjudgment caused by crosstalk. Coupling of a strong electromagnetic field is suppressed, and the signal management effect and the transmission stability are improved.

The invention provides a low-voltage flexible DC system fault detection method based on complex domain analysis, and the method comprises the steps: obtaining and sampling a transient current signal in a low-voltage flexible DC system, fitting the transient current signal into a linear combination of a group of exponential functions, and obtaining a fitting exponential function; solving the fitting exponential function in a Z domain based on a Pade approximation method to obtain a complex index of the fitting exponential function; determining a fault threshold frequency according to the operation parameters of the low-voltage flexible DC system; the complex index is used as an analysis object, and the natural oscillation frequency of the low-voltage flexible direct-current system is obtained through formula calculation; and taking the fault threshold frequency as a state circle radius, constructing a fault discrimination model based on a complex plane, comparing the natural oscillation frequency with the fault threshold frequency, and outputting a fault detection result of the low-voltage flexible DC system in combination with a real part of a complex index. According to the method, the sensitivity to noise can be reduced, and meanwhile, the requirement of fault detection for speed is met.

The invention discloses a partial discharge monitoring system, method, equipment and medium for a switch cabinet, and belongs to the technical field of insulation state monitoring of high-voltage electrical equipment, and the partial discharge monitoring system comprises an NO2 gas detection module, a pulse current signal acquisition module, a signal processing module, a data transmission module, a data analysis and diagnosis module and a user display and alarm module. According to the invention, by integrating dual monitoring technologies of NO2 gas detection and transient current signal acquisition and combining signal processing, data transmission, data analysis and diagnosis and a user display and alarm module, high-precision and high-reliability online monitoring of partial discharge of the high-voltage switch cabinet is realized; the defects that a traditional single method is prone to electromagnetic interference, low in sensitivity and not suitable for long-term online monitoring are overcome, and the anti-interference capacity, diagnosis accuracy and operation stability of a monitoring system are improved.

The invention discloses an adaptive virtual impedance-based fault current limiting method for a network-forming converter, and belongs to the technical field of converter control. Comprising the following steps: collecting grid-side voltage, converter-side voltage and converter output current; carrying out current amplitude calculation on the grid-side voltage quantity to obtain a current effective value of the port of the converter; judging whether the current effective value of the current transformer port exceeds a current threshold value of the current transformer; and if yes, self-adaptive virtual impedance is introduced to carry out converter fault current limitation. The resistance part of the virtual impedance is used for suppressing surge current at the beginning of a fault; and the reactance part is used for suppressing the effective value of the fault transient current within the current limiting range. In the fault process, the current virtual impedance value is adaptively changed according to the effective value of the current overcurrent, and the virtual impedance can be automatically quitted after the fault end stage. The method is suitable for fault current suppression of the network-forming converter in various control modes, and has good feasibility and practical value.

The invention discloses a method for measuring and analyzing residual magnetism characteristics of an iron core. According to the method, a to-be-detected iron core is demagnetized, preset residual magnetism is set, direct-current voltage excitation with opposite polarities, the same amplitude and the same duration is applied to a primary winding of the to-be-detected iron core, and transient current response signals are synchronously collected; two groups of current under positive / negative polarity excitation are extracted, and the residual magnetism direction is judged by comparing the change rate of the current; a curve of equivalent resistance changing along with time is calculated based on forward current and voltage, a resistance value corresponding to a characteristic inflection point moment is selected, the resistance value is substituted into a pre-established residual magnetism-equivalent resistance empirical formula to deduce the magnitude of residual magnetism, and a matched iron core residual magnetism detection and demagnetization integrated system integrates information management, residual magnetism detection, demagnetization and display modules. And closed-loop automation of detection, analysis and demagnetization is realized. According to the method, a magnetic field sensor is not needed, the residual magnetism direction and size can be synchronously obtained in a high-precision and robust mode only through port electric signals, and the method is suitable for on-site off-line or live detection.

The invention discloses an electric energy metering error evaluation method and system for a direct current charging pile, equipment and a medium, and the method comprises the steps: constructing an electric energy disturbance response function based on transient voltage and transient current, and effectively quantifying the transient metering deviation caused by measurement lag, voltage drop, current peak and other factors in the actual operation of the direct current charging pile. Error reconstruction modeling has higher dynamic adaptive capacity and physical rationality, the limitation that in the prior art, the influence of the high-variable-load working condition on metering cannot be reflected is broken through, and the accuracy and timeliness of direct-current charging pile error monitoring are greatly improved. Besides, a standard error is introduced to carry out fitting calibration on a reconstruction error and carry out energy conservation verification, thereby realizing verifiability on a physical level and controllability in engineering implementation, enhancing credibility and authority of an evaluation result, constructing a closed-loop analysis mechanism from error evaluation to metering correction and then to conservation verification, and improving reliability and reliability of the evaluation result. And the closeness and the adaptive capability of the overall error evaluation are improved.

The invention relates to an IGBT parallel current sharing control circuit and method for turn-off transient current change rate detection, and the circuit employs a PCB Rogowski coil probe to carry out the non-contact detection of the turn-off current change rate of a parallel device, thereby accurately judging the non-current sharing characteristic of the parallel device. The problem of integrated design of a traditional detection scheme in large-current and high-power-density application is effectively solved; meanwhile, by designing a current change rate peak holding circuit, the holding time of a peak signal is remarkably prolonged, and the performance requirement on the ADC sampling rate is greatly reduced; a reset branch is additionally arranged for the peak holding circuit, and the peak output value in the last period is zeroed in the turn-on transient state by using a driving signal, so that the charge accumulation effect is effectively eliminated, and the sampling precision of the system is guaranteed; the regulation and control part of each parallel branch only needs to be additionally provided with two passive elements including the control switch and the capacitor, current sharing control can be achieved by adjusting the access time of the bypass branch, the structure is simple, cost is low, and good popularization applicability is achieved.

The invention relates to the technical field of power grid protection based on relay equipment, and discloses a power grid protection method and device based on the relay equipment, electronic equipment and a medium, and the method comprises the steps: building a power distribution network topological structure through obtaining the data and switch states of the relay equipment in real time, and precisely recognizing main protection equipment and backup protection equipment; according to the method, the transient current is calculated, the capability of capturing fault features is improved through real-time dynamic analysis, target setting parameters of the main protection device and the backup protection device are solved through a constructed preset target function, and the states of the main protection device and the backup protection device are set. The method has the advantages that the safety and reliability of a power system are improved, the limitation of a traditional relay protection constant value method in a complex and dynamic power distribution network environment is solved, efficient access of new energy is promoted, large-scale power failure risks are reduced, and the method has important application value and popularization prospects.

The invention provides an electrical equipment fire risk assessment system and method for a power distribution network, and relates to the technical field of fire risk assessment, and the method comprises the steps: extracting fault arc features and odd harmonic features of target electrical equipment from a current signal and a voltage signal of the target electrical equipment in the power distribution network; carrying out gradient analysis on the coupling effect of the target electrical equipment due to harmonic heating and load fluctuation thermal shock to obtain a sensitive gradient of thermal runaway generated by the target electrical equipment, and further determining a thermal stability margin of the target electrical equipment under a harmonic distortion working condition; according to the transient current impact value of the target electrical equipment in the nonlinear load fluctuation process, determining an accumulative effect coefficient of thermal aging generated by the target electrical equipment; and then performing fire risk assessment on the target electrical equipment to obtain a risk assessment index of the fire of the target electrical equipment. According to the invention, the method can achieve the evaluation of the fire risk of the electrical equipment under the complex working condition of current and voltage signal distortion caused by a nonlinear load in a power distribution network.

The invention relates to the technical field of power grid faults, in particular to a coal mine power grid fault positioning method, which comprises the following steps: collecting transient current traveling wave signals generated when a fault occurs; executing a first layer of PSO to adaptively find an optimal parameter combination for the VMD, and processing a transient current traveling wave signal based on MRSVD to obtain an input signal of the VMD; inputting an input signal into VMD based on the optimal parameter combination, decomposing to obtain intrinsic mode function components, calculating a kurtosis-permutation entropy index of the intrinsic mode function components, selecting the intrinsic mode function component with the highest value as an optimal mode component, extracting initial traveling wave arrival time by combining a symmetric differential energy operator, executing a second-layer PSO, and obtaining a second-layer PSO; correcting the initial traveling wave arrival time through a physical constraint optimization model, and adjusting the traveling wave velocity by adopting a self-adaptive wave velocity estimation strategy to obtain the corrected traveling wave head time and traveling wave velocity; and calculating the position of the fault point based on the corrected traveling wave head time and traveling wave velocity. According to the invention, rapid and accurate positioning of fault points is realized, and the robustness is high.

The invention discloses a single-phase earth fault line selection method based on double-layer parameter adaptive optimization, and the method comprises the following steps: collecting three-phase current corresponding to each feeder line of a target system after the single-phase earth fault of the target system occurs, and carrying out the calculation to obtain zero-sequence transient current; inputting the zero-sequence transient current into a self-adaptive optimization decomposition model for self-adaptive decomposition to obtain an intrinsic mode component of a corresponding feeder line; extracting transient characteristics based on the intrinsic mode component and constructing a transient characteristic matrix; and inputting the transient characteristic matrix into a pre-trained optimization mechanism fault line selection model, outputting a fault posterior probability corresponding to each feeder line, and determining a fault feeder line according to the fault probability. According to the invention, double-layer parameter adaptive optimization is used for carrying out joint optimization on key parameters of a decomposition model and key parameters of a line selection model, so that effective feature extraction and reliable discrimination can still be realized under the conditions of complex zero-sequence transient current high-frequency components and unclear features caused by the access of the distributed power supply; therefore, misjudgment and missed judgment are reduced, and the fault line selection accuracy and robustness are improved.

The invention provides an IBIS model transient characteristic simulation method and system and computer equipment, and the method comprises the steps: reading I / V data and V / T data in an IBIS model file, and constructing a KCL-based equivalent circuit equation; the completeness of the V / T data is judged, different algorithms are adopted for different pre-simulation according to the different completeness of the V / T data, and four current modulation parameters of a pull-up transistor PU and a pull-down transistor PD are calculated; and performing transient response simulation of the IBIS model according to the solved four current modulation parameters to obtain transient current of the pull-up transistor PU and the pull-down transistor PD. According to the scheme, the problem that the adaptability to IBIS models of different versions is insufficient in the prior art is solved, and IBIS transient characteristic simulation compatible with all versions is achieved.

The invention discloses a network construction type converter fault current limiting method considering power angle stability, and belongs to the power electronic technology. According to the method, firstly, an active power adaptive adjustment coefficient is introduced into an active-frequency control loop, the power angle variation of the converter at the moment of a fault is suppressed, and the transient power angle stability of the converter is guaranteed; secondly, an output voltage reference value is adjusted through a reactive power-voltage control loop, the voltage difference between the converter and the power grid is reduced, and the current steady-state component in the fault period is restrained; and finally, a variable virtual reactance is introduced into a voltage outer ring, and a transient current impact component at the fault moment is suppressed. The current limiting method is provided for the grid-forming type converter when the grid-side voltage symmetrically drops, continuous increase of the output current in the converter fault period can be restrained, meanwhile, power angle instability is prevented, and the method has the advantages of being high in response speed, good in current limiting effect and high in power angle stability.

The present application relates to a kind of offshore wind power dc collection system single-end protection method based on transient current rate of change, the transient fault current of each collection line of dc collection system is calculated, the transient fault current is the difference between current value and steady-state current value before fault;The transient current rate of change of each line positive and negative is calculated;If the inter-pole unbalance voltage is greater than the first voltage threshold, then start monopolar ground fault protection process, according to the polarity and amplitude relationship of the transient current rate of change of each line positive and negative, determine fault line and fault pole;If the inter-pole measurement voltage is less than the second voltage threshold, then start bipolar short-circuit fault protection process, according to the polarity and amplitude relationship of the transient current rate of change of each line positive and negative, determine fault line and fault pole.Compared with prior art, the present application has the advantages of high accuracy, high adaptability and strong reliability.

The invention discloses a fault isolation and self-healing control method for a multi-terminal flexible direct current power supply system in the field of flexible direct current power supply, and aims to solve the technical problems that a traditional multi-terminal flexible direct current system is lagged in fault positioning, low in isolation speed, not timely in self-healing response and low in power supply recovery precision. According to the method, through a closed-loop control logic of fault feature extraction, accurate positioning, rapid isolation and dynamic self-healing, a fault identification model is constructed based on collaborative features of transient current and voltage, and millisecond-level positioning of a fault section is realized in combination with a simplified fault positioning formula; an IGBT series solid-state circuit breaker is adopted to realize rapid fault isolation, a self-healing scheduling strategy of load priority and resource adaptability is introduced, and power supply is recovered through cooperative scheduling of a distributed power supply and an energy storage unit. The fault isolation time is shortened, the power supply recovery success rate is improved, the voltage recovery deviation is reduced, and the power supply reliability and the operation toughness of the multi-terminal flexible direct current power supply system are remarkably improved.

The application provides a power distribution line fault positioning method and system. Transient current traveling wave signals of each monitoring section of a power distribution line and measurement data of a doubly-fed wind turbine are collected when a fault occurs. Equivalent inductance analysis is performed on the doubly-fed wind turbine based on the measurement data to obtain a dominant characteristic frequency band. A plurality of transient signal characteristic quantities are determined according to the dominant characteristic frequency band and the transient current traveling wave signals. The energy distribution of the transient current is determined according to all the transient signal characteristic quantities. The transient energy of each monitoring section of the power distribution line is evaluated according to the energy distribution to obtain the distribution difference of each monitoring section. When the distribution difference of any monitoring section exceeds a threshold value, the monitoring section is determined to be a fault section, and the distance of the fault point in the fault section is determined. The scheme of the application can be used to position the fault of a weak power grid power distribution line under the coupling mechanism of the transient response characteristics of the doubly-fed wind turbine and the meshed loop.

The invention provides a gallium nitride power device packaging parasitic parameter degradation monitoring method. The method comprises the following steps: establishing a high-frequency RLC oscillation model of a gallium nitride power device comprising packaging parasitic parameters under a high-frequency switching condition; judging whether the oscillation amplitude of the switch transient current change rate measurement waveform is reduced compared with the switch transient current change rate reference waveform or not; determining the correlation between the packaging parasitic parameter and the switching transient current change rate oscillation amplitude; predicting whether the packaging of the gallium nitride power device is degraded or not; the change of the change rate of the transient current of the switch is reflected through packaging parasitism, and whether the packaging of the gallium nitride power device is degraded or not is monitored by using packaging parasitism parameters, so that an early signal of the packaging degradation of the device can be effectively identified, and an early tiny packaging degradation sign can be captured; and the accuracy of packaging degradation monitoring is high.

The invention relates to the technical field of power distribution monitoring, and discloses an electrical equipment operation monitoring system based on intelligent control, and the system comprises a grid structure recognition unit which collects a switch contact signal, and determines a real-time power grid topology model; the short-circuit capacity evaluation unit reconstructs a node admittance matrix by using a real-time power grid topology model, and calculates node equivalent short-circuit impedance; the transient feature extraction unit samples a node transient current signal and extracts a high-frequency transient component sequence; a monitoring fixed value follow-up setting unit determines a mapping relation between node equivalent short-circuit impedance and short-circuit capacity, and a monitoring threshold value is corrected in a follow-up mode; according to the system and the method, a physical coupling mechanism of the monitoring constant value and the power grid rigidity is established, sensitivity mismatch caused by grid structure reconstruction is eliminated, and the sensing capacity of the system to the initial degradation of equipment is enhanced. The transient integral energy of the high-frequency transient component sequence is calculated, and an abnormal operation signal is generated when the transient integral energy deviates from a monitoring threshold value.

This invention discloses a load current source module, readout system, and imaging device for image sensor readout, relating to the field of image sensor technology. It includes: a current mirror circuit; a negative impedance transformation circuit, which generates negative resistance or capacitance to cancel out the parasitic resistance or capacitance of the VSL itself; and a charge / discharge acceleration circuit. This invention allows the load current source module to internally incorporate a negative impedance transformation circuit and a charge / discharge acceleration circuit. On one hand, the negative impedance transformation circuit generates negative impedance to cancel out the parasitic capacitance and resistance present in the VSL signal establishment, thereby accelerating the small signal establishment speed. On the other hand, the charge / discharge acceleration circuit provides a larger transient current to accelerate the large signal establishment speed. In other words, the load current source module in this application does not change the operating point design of the main current mirror circuit, effectively accelerating the VSL establishment time.

The invention provides a transformer residual magnetism detection method for improving direct current demagnetization, and belongs to the technical field of power equipment detection. The method comprises the following steps: demagnetizing a transformer iron core to eliminate an interference magnetic field, applying direct current excitation through a special winding to generate controllable preset residual magnetism, establishing a detection circuit in which a primary side winding is connected with an external resistor in series and a secondary side winding is open-circuited, and sequentially applying direct current small signal excitation with the same size and opposite directions, the method comprises the following steps: collecting forward and reverse transient current and voltage waveforms, comparing current change rate after filtering to judge the residual magnetism direction, solving the equivalent resistance of an iron core based on the waveform consistent with the residual magnetism direction, obtaining a detection result by combining the monotone fitting relationship between the resistance and residual magnetism, and finally assisting verification and calculating a relative error through an energy method. And if the error does not exceed 5%, it is determined that detection is effective, accurate and lossless detection of the magnitude and direction of the residual magnetism can be achieved, and detection reliability and engineering applicability are effectively improved.

This invention discloses a method, system, and apparatus for extracting the fundamental phasor of fault transient current, relating to the field of power system fault transient current analysis. The method involves acquiring N transient sampled currents and dividing them into M subsets according to a preset partitioning strategy. The discrete Fourier transform (DFT) output of each subset is then determined. Combining the DFT output expressions of each subset, the first DFT output corresponding to the first exponentially decaying DC offset component and the second DFT output corresponding to the second exponentially decaying DC offset component under the target subset are determined. Finally, the DFT output of the current fundamental phasor is determined by combining the DFT output expression and output results of the target subset, thus obtaining the fundamental phasor. This scheme pre-establishes a preset fault transient current discrete model and sets a preset partitioning strategy, achieving high-precision and rapid extraction of the fundamental phasor, which is beneficial for improving the reliability of power system relay protection.

The invention relates to an automatic tool test circuit and test method based on a super capacitor. The automatic tool test circuit comprises a control unit, a switch S3, a super capacitor C16, a resistor R57, a current-limiting resistor R35, a resistor R56 and a to-be-tested module. The control unit is used for controlling on and off of the switch S3; the positive electrode of the super capacitor C16 is sequentially connected with a resistor R57, a switch S3 and a resistor R56 in series, and the negative electrode of the super capacitor C16 is grounded; the module to be tested comprises a sampling resistor R34 used for detecting an overcurrent and generating a voltage difference; the first end of the sampling resistor R34 is connected with the second end of the resistor R56, and the second end of the sampling resistor R34 is grounded; the super capacitor C16 is used for storing electric energy and providing current at the moment of discharging, the super capacitor C16 discharges at the moment of closing of the switch S3, and instantaneous current is generated on the sampling resistor R34. The method is low in cost, safe, reliable and easy to implement in factory flow line production, and remarkable competitive advantages are provided for enterprises.

The invention relates to the field of circuit breakers, in particular to a quantitative analysis method for the influence of transient current on the residual electrical life of a high-voltage circuit breaker, which comprises the following steps: calculating the influence index of the transient current on the residual electrical life of the high-voltage circuit breaker; constructing a related parameter time sequence; calculating an influence factor of the relevant parameters at the current moment on the relevant parameters at the next moment; predicting numerical values of relevant parameters at the next moment; calculating the influence index of the transient current at the next moment on the residual electrical life of the high-voltage circuit breaker; evaluating the decay speed of the residual electrical life, and dynamically adjusting the maintenance cycle. The method has the advantages that the frequency characteristic of the fault current and the waveform distortion characteristic caused by the harmonic wave are brought into the evaluation system of the residual electrical life, the limitation that only the current amplitude is considered in the traditional method is broken through, the actual physical process of the contact ablation by the transient current can be reflected more truly and more comprehensively by constructing the comprehensive quantitative model, and the evaluation accuracy of the residual electrical life is improved. And the scientificity of an evaluation model and the accuracy of a prediction result are fundamentally improved.

The utility model relates to the technical field of avionic equipment protection, in particular to a lightning protection filtering assembly. Comprising a shell, and a lightning protection module, an anti-reverse module and an EMI filtering module are packaged in the shell. The lightning protection module adopts a transient voltage suppressor (TVS) diode, the clamping voltages are 121V, 19.9 V and 72.7 V respectively, and the response time is less than or equal to 5 microseconds; the anti-reverse module is integrated at a power supply input end, a diode with reverse withstand voltage greater than or equal to 1200V is adopted, and the transient current bearing capacity is greater than or equal to 50A / mu s; the EMI filtering module comprises a pi-type filtering circuit topology; the input interface comprises two circular electric connectors (X1 and X2); and the output interface is a rectangular connector (J3) and is used for integrally outputting all signals and a power supply which are subjected to protection processing. According to the utility model, through module integration, interface centralization and passive high-reliability design, the space and resource waste is reduced, and the module has obvious volume, weight and performance advantages.

This invention discloses a model predictive current control method and system based on online parameter identification. The method independently identifies the resistor using steady-state average information within a switching cycle, and then identifies the inductor using transient current ripple information combined with a logarithmic linearization method. Next, the identified real-time resistance and inductance values ​​are input into a deadbeat-free model predictive current control algorithm to update the coefficients of the predictive model. Based on the latest model parameters and reference current, the controller calculates the ideal voltage vector required to eliminate current error at the next moment, and after amplitude limiting, drives the switching transistor through a PWM module, thereby achieving high-performance control of the coil current. The system includes an online parameter identification module and a model predictive control module. By using this invention, high accuracy and high stability of the magnetic bearing power amplifier are ensured under all operating conditions. This invention can be widely applied in the field of electronic power technology.

A flexible low-frequency transmission line inverse time protection method and system are provided. The method uses single-ended electrical quantity to constitute the criterion, after the fault occurs, the signal acquisition device is used to sample the phase current and voltage, and the resulting voltage and current are subjected to the Karenbauer transform to obtain the line mode and the zero mode components, and the integral value of the fault modulus components is used to construct the transient current energy, and the transient energy is used to construct the new inverse time limit characteristic curve equation, and the transition resistance compensation coefficient is introduced to improve the inverse time limit protection performance of the inverse time protection. The method is aimed at accelerating the action time of the protection when a fault occurs in a flexible low-frequency transmission line, and adopts the fault component to construct the transient energy value.

This application relates to the field of terahertz emission, specifically providing a low-frequency terahertz emitting device and its fabrication and usage methods. The device includes an excitation material, which is a heterojunction formed by a perovskite layer and a high-resistivity silicon layer. It also includes a first metal layer disposed outside the perovskite layer and a second metal layer disposed outside the high-resistivity silicon layer. During fabrication, a perovskite solution is first spin-coated onto the high-resistivity silicon to form a perovskite layer, and finally, the metal layers are deposited by vapor deposition. During use, a femtosecond laser is incident from one side of the perovskite layer, and a voltage is applied between the first and second metal layers. The applied electric field of this application enhances the interfacial band bending and widens the depletion layer, while simultaneously forming a stable potential gradient in the thickness direction. This makes the transient current change smoother, increases the time constant, and reduces the rate of change of the transient current over time, thereby increasing the proportion of the low-frequency terahertz component and achieving enhanced low-frequency radiation.