774 results about "Utility frequency" patented technology

The invention provides a multi-dimensional electrical equipment insulation analysis and evaluation method, and relates to the technical field of electrical equipment insulation online detection and intelligent diagnosis. According to the method, an electrically isolated direct current detection channel is constructed in a neutral point small resistance grounding system, controllable direct current detection signals are injected, micro direct current leakage response signals are collected, and after zero drift correction, temperature compensation and power frequency ripple suppression are carried out, layered attribution is carried out in combination with primary system topology and an equipment ledger, and a multi-dimensional response matrix is formed. According to the method, environment and working condition normalization is realized through factor rejection and robust pull-back, a mechanism model containing leakage channel equivalent parameters and path constraints is established, multi-working-condition data is fused to calculate equivalent insulation parameters and credibility indication quantity, and a multi-dimensional insulation representation vector is generated. And performing time sequence analysis on the representation vector, extracting degradation and abrupt change characteristics, outputting a health index and a risk level, and realizing quantitative evaluation and intelligent early warning of the insulation state.

The invention relates to the technical field of ground resistance detection, in particular to a single-core cable ground resistance detection method capable of resisting strong power frequency interference. High-frequency signals are injected in a non-contact mode through a coupling type capacitor clamp, background voltage and current signals are collected firstly, and injection frequency far away from power frequency and harmonic waves is selected through Fourier analysis; cancelling background noise by adopting a normalized least mean square adaptive filter to generate an enhanced signal; the signal is down-converted to a base band through digital quadrature demodulation, a Kalman filter estimates the amplitude and the phase in real time, and the state and noise parameters are periodically calibrated through a compressed sensing algorithm; and finally, loop impedance is calculated according to the voltage and current amplitudes and the phase difference to obtain grounding resistance. The method has the advantages of being non-contact, high in safety, strong in anti-interference capability, high in measurement precision and the like, and is suitable for monitoring the grounding state of the cable in a complex electromagnetic environment.

The invention discloses a high-voltage cable operation state on-line monitoring, intelligent early warning and fault positioning system, particularly relates to the technical field of power equipment insulation monitoring, and is used for solving the problems that transient discharge signals generated in the cable insulation degradation process are difficult to effectively capture and accurate fault positioning cannot be realized in the prior art. The method comprises the following steps: collecting transient leakage current signals and traveling wave propagation characteristic parameters, performing phase correlation analysis on leakage current pulses and power frequency voltage to identify discharge types, and performing variational mode decomposition and Hilbert-Huang transform on the signals to respectively extract complexity characteristics and energy distribution characteristics; signal logic conflicts are judged by analyzing similarity and statistical distance among characteristics of a plurality of monitoring points, and collaborative diagnosis is started or traveling wave distance measurement is directly utilized to carry out insulation state evaluation and fault location. And finally, differential early warning levels are generated according to the diagnosis result, and fault line selection and positioning information is output to realize real-time monitoring, intelligent early warning and accurate positioning of the operation state of the high-voltage cable.

The invention discloses a column type distribution transformer winding abnormity detection system and detection method. The detection system comprises a frequency response detection instrument, a signal coupling assembly, an impedance matching module and a data processing module. The frequency response detection instrument is used for outputting a frequency sweep excitation signal and collecting a winding response signal; the signal coupling assembly is used for isolating power frequency voltage and filtering low-frequency interference; the impedance matching module is used for adjusting output impedance and input impedance to realize matching with electrical characteristics of different windings; and the data processing module is used for constructing an equivalent detection loop model, completing frequency response simulation calculation and carrying out frequency domain analysis and anomaly identification on an actually measured response curve. According to the invention, electrified state diagnosis of distribution transformer winding structure abnormity (such as deformation and loosening) can be realized.

The invention relates to the technical field of power system relay protection, and discloses a relay protection device mutual inductor adjustment system and method, and the system comprises a system connection initialization module, a data collection reference data generation module, a power frequency background signal offset module, a pilot frequency current injection error calibration module, and a calibration result verification output module. The method comprises the following steps: initializing sampling frequency of a to-be-calibrated mutual inductor and calibration source output precision of a calibration system, collecting amplitude and phase data of real-time power frequency current of the mutual inductor, generating offset current with equal amplitude and opposite directions through power electronic compensation based on reference data, optimizing offset current parameters through a closed-loop adjustment algorithm, and adjusting the offset current parameters through a closed-loop adjustment algorithm. Power frequency background signal offset is completed, pilot frequency calibration parameters are set, a difference value between a mutual inductor pilot frequency output signal and a calibration source standard signal is extracted by adopting a zero pointing technology, an optimal calibration coefficient is automatically calculated, verification of a calibration result is completed, and accuracy and reliability of the calibration result are ensured.

The invention relates to the technical field of ammeter fault detection, and provides an intelligent ammeter series arc fault detection method, system and device, a medium and equipment, and the method comprises the steps: firstly obtaining an ammeter data set of an intelligent ammeter, which comprises a pre-ammeter voltage, a post-ammeter voltage and a total loop current in a continuous power frequency period, and then carrying out the division through a sliding time window, obtaining a plurality of ammeter data windows; for each window, calculating a voltage difference sequence and a dynamic loss impedance sequence; when the absolute value of the total loop current is smaller than a preset threshold value, determining the current zero-break interval of each power frequency period and the current zero-break time corresponding to the window; determining an arc voltage estimation value according to a voltage difference between non-zero-break intervals in the zero-break interval; and finally, integrating the current zero break time, the arc voltage estimated value and the dynamic loss impedance of each window to judge whether a series arc fault exists, and if so, triggering a protection action. According to the embodiment of the invention, high-reliability identification of the series arc fault is realized.

The invention discloses a construction method and a modulation method of a three-port multi-frequency MMC topology based on bridge arm multiplexing, and relates to the technical field of power electronics. The construction method comprises the steps that sub-modules of a traditional double-bridge-arm MMC are integrated and optimized into a three-bridge-arm structure through a current conversion branch, independent energy interaction of three ports is achieved through an auxiliary bridge arm, multi-frequency operation modes of power frequency, frequency division, direct current and the like are supported at the same time, and therefore the utilization rate of the bridge arm sub-modules is increased, and the energy utilization rate of the MMC is increased. And the overall size and the manufacturing cost of the converter are reduced. Based on three-port multi-frequency coordination control and power balance requirements, a modulation method of the topological structure is provided, a multi-frequency coordination modulation strategy is adopted, frequency offset is performed through an auxiliary bridge arm to reduce cross interference of port frequency, and output waveform quality is improved through multi-objective optimized capacitor voltage balance control. And meanwhile, direct-current side faults are effectively eliminated by means of the auxiliary bridge arm.

The invention belongs to the field of power transmission line parameter measurement, and discloses a live-line testing device and method for mutual inductance line parameters and zero-sequence impedance parameters. The device comprises a double-circuit line simulation module, a pilot frequency excitation module, a power frequency simulation module, a synchronous acquisition module and a signal processing module. The isolation transformer simulates a double-circuit line, the pilot-frequency power supply provides pilot-frequency excitation signals, the measurement unit realizes synchronous acquisition, and the signal processing module performs anti-interference and amplification processing. The method comprises the steps of line simulation wiring, synchronous time synchronization, pilot frequency signal acquisition, parameter calculation and error verification, and pilot frequency parameters are converted into power frequency parameters by using a frequency conversion formula. According to the invention, power frequency interference can be effectively suppressed in a charged environment, high-precision measurement of zero-sequence impedance and mutual inductance parameters of a mutual inductance line is realized by using pilot frequency excitation and Beidou synchronization technologies, the measurement error is remarkably reduced, the safety and reliability are remarkably improved, and powerful technical support is provided for safe and stable operation of a power system.

The invention discloses an offshore wind power collecting and sending-out system and method based on a multi-port multi-frequency alternating current and direct current hybrid integrated platform, and belongs to the field of power transmission and distribution of power systems. The system comprises an intermediate-frequency, power-frequency and low-frequency wind power collection subsystem, an offshore integrated platform, a direct-current sending-out submarine cable, a low-frequency sending-out submarine cable, an onshore converter station and an onshore frequency conversion station. The various wind power collection subsystems respectively collect wind turbine generator group outputs with corresponding frequencies and send the wind turbine generator group outputs to the offshore integrated platform; the offshore integrated platform converts intermediate-frequency, power-frequency and partial low-frequency electric energy into direct current and then transmits the direct current to the onshore converter station through the direct-current sending-out submarine cable, and the converter station converts the direct current into power-frequency alternating current; and after being boosted, the other low-frequency electric energy is sent to a land frequency conversion station through a low-frequency sending-out submarine cable to be converted into power-frequency alternating current, so that efficient collection and grid-connected sending-out of multi-frequency wind power resources are realized. According to the invention, the problem that a plurality of independent platforms need to be built in a complex multi-point grid-connected scene in the prior art can be solved.

The invention discloses a power frequency phase adaptive acquisition device, and relates to the technical field of electric power signal measurement, the device acquires electric field data at a gap through an electric field sensor integrated on an edge shell, calculates electric field intensity fluctuation, and generates interference diagnosis information in combination with a preset interference determination threshold value; when the interference diagnosis information shows that effective interference exists, the electric field intensity variable quantity is calculated, a mapping model is established based on a proportionality coefficient obtained through an experiment so as to obtain zero crossing point offset, and the sampling trigger moment of a zero crossing point detection module is corrected; the clock synchronization module calculates a phase difference by taking the corrected trigger moment as a reference, dynamically adjusts a calibration frequency by combining a phase difference threshold value, and outputs a synchronized system clock signal; and the control system takes the synchronized system clock signal as a trigger signal, collects power frequency phase data according to a power frequency period, and stores the power frequency phase data to a database through a transmission unit, thereby realizing high-precision power frequency phase collection.

The invention discloses an isolation type split-phase inverter circuit and a control method thereof. The isolation type split-phase inverter circuit comprises an isolation DC / DC module circuit and a power frequency rectification module circuit. The isolation DC / DC module circuit comprises an input-side full bridge, a three-end transformer and two output-side circuits, an input-side winding of the three-end transformer is connected with a midpoint of a bridge arm of the input-side full bridge, and the input-side full bridge is connected with a filter capacitor C1 in parallel; two output side windings of the three-end transformer are respectively connected with corresponding output circuits through a resonance network circuit, the two output circuits are connected to a power frequency rectification module circuit through filter capacitors C4 and C5, and the negative electrode of the first output circuit and the positive electrode of the second output circuit are connected to form an interface N; the power frequency rectification module circuit comprises a rectification full-bridge circuit, and an interface L1 and an interface L2 are obtained after rectification. Through cooperative control of direct transmission of integrated topology and voltage signals, a complex parameter matching algorithm is not needed, breakthrough in structure simplification, energy conversion efficiency, control convenience, cost control and safety is achieved, and the method is suitable for various power conversion scenes.

The invention discloses an offshore wind power frequency conversion gathering and sending control method, device and system based on onshore integration, and belongs to the technical field of power transmission and distribution of power systems, and the method comprises the steps: converting first AC electric energy generated by an intermediate-frequency / power-frequency wind power plant into first DC electric energy through an offshore converter station; the first direct-current electric energy is transmitted to a land integration station through a direct-current submarine cable; second alternating-current electric energy generated by the low-frequency wind power plant is transmitted to the land integration station through a low-frequency alternating-current submarine cable; and converting the second alternating-current electric energy into second direct-current electric energy in the land integrated station, carrying out collection and power frequency conversion on the first direct-current electric energy and the second direct-current electric energy, and transmitting power frequency alternating-current electric energy obtained after conversion to a land power grid. Therefore, by implementing the application, the problem that the electric energy cannot be transmitted at low cost due to the fact that it is difficult to directly send the electric energy of different frequencies out of the system for topological combination in the prior art can be solved.

The invention discloses a rectifier bridge arm fault identification method and system circuit based on multi-characteristic current waveform analysis, and relates to the technical field of rectifier bridge arm fault identification, and the method comprises the steps: collecting a current signal of an AC input side of a rectifier bridge through a current sensor, and obtaining an original current time domain waveform after filtering conditioning; performing period division on the original current time domain waveform based on a voltage synchronization signal, and outputting a positive half-cycle conduction interval and a negative half-cycle conduction interval in each power frequency period; in each power frequency period, performing square integral operation on the current waveforms of the positive half-cycle conduction interval and the negative half-cycle conduction interval to obtain a positive half-cycle energy value and a negative half-cycle energy value, and calculating an energy unbalance degree; and windowing fast Fourier transform is carried out on the original current time domain waveform, amplitudes and phases of third, fifth and seventh characteristic harmonics are extracted to form a harmonic characteristic vector, the vector is matched with a pre-stored bridge arm fault harmonic fingerprint template, and the matching degree of each fault type is obtained.

The invention relates to the technical field of cable insulation detection, and discloses a power cable insulation state evaluation method and system based on multi-dimensional feature fusion, and the method comprises the steps: collecting a high-frequency current signal on a cable grounding wire, extracting a power frequency phase, a discharge amplitude and a pulse frequency band width, and carrying out the normalization processing, thereby obtaining a sample set; calculating a local sparseness adaptive factor of each sample point, and calculating an energy weighted local density of each sample point; calculating the relative distance of each sample point, constructing a decision value, and determining the sample point with the larger decision value as a clustering center; calculating the path transmission reliability of the non-clustering center sample points relative to each clustering center, distributing the sample points with the path transmission reliability meeting a preset condition to the corresponding clustering center, and if the preset condition is not met, marking the sample points as noise; and extracting statistical characteristics according to the separated discharge clusters, and evaluating the insulation state of the cable by using a preset fault diagnosis rule base. According to the invention, the accuracy of cable insulation state evaluation can be improved.

The invention provides a non-power-cut test method for mutual inductance parameters of a power transmission line under excitation of different-frequency signals and a related device, and solves the problems of difficulty in accompanying stop and high safety risk of adjacent lines. The method comprises the following steps: selecting one circuit in the same corridor for power failure, connecting the head end with an induced electricity suppression device, and performing three-phase short-circuit grounding at the tail end; injecting a different-frequency sinusoidal current of 45-55Hz into the power failure line; the synchronous measurement device collects head and tail voltage and current of a running line based on a satellite synchronous clock; extracting pilot frequency signals through two-stage notch filtering and Fourier transform; and different-frequency zero-sequence self-impedance and mutual impedance are calculated and converted into power-frequency impedance. According to the invention, accurate test without power failure can be realized, and safety and power supply reliability are guaranteed.

The invention discloses an intelligent diagnosis system for power utilization abnormal information acquisition, particularly relates to the technical field of power system monitoring, and is used for solving the problems of waveform distortion and broadening caused by transmission line distribution parameters in the long-distance wired transmission process of an existing system. The system collects abnormal characteristic waveform data through a distributed intelligent terminal, selects a characteristic harmonic component in the power frequency voltage of a power line to construct an inherent test signal, extracts the envelope form similarity of a response signal and the test signal through envelope analysis as a first distortion evaluation index, and obtains a second distortion evaluation index after statistical significance judgment. Performing instantaneous frequency stability analysis on the signal with significant distortion to obtain a second distortion evaluation index, and finally generating a corresponding waveform compensation parameter based on double indexes to realize real-time compensation correction; the integrity of the abnormal characteristic waveform in the transmission process is effectively maintained, and the accuracy and reliability of power consumption abnormity diagnosis are remarkably improved.

The invention discloses a medium-frequency transformer insulation electrothermal aging evaluation method, a test device and a storage medium, and relates to the technical field of power transformers. The medium-frequency transformer insulation electric heating aging test device comprises a function signal generator, a high-voltage power amplifier, a protection and isolation unit, an electric-heat combined aging oven and a detection and monitoring unit. The electrothermal aging evaluation method comprises the following steps: acquiring an aged sample, testing the ultimate tensile strength and polymerization degree of the aged sample, introducing a frequency correction factor to correct an attenuation constant under a power frequency condition, establishing tensile strength attenuation equations under different frequencies, and evaluating the tensile strength of the aged sample. And respectively fitting the maximum value of the accumulated loss rate and the change rate of the accumulated loss rate under different frequencies to obtain a polymerization degree accumulated loss rate improvement formula, and carrying out aging characteristic analysis on the insulation of the intermediate-frequency transformer according to the actual working condition of the insulation of the intermediate-frequency transformer. According to the technical scheme, the blank of medium-frequency transformer insulation electrothermal aging research is filled.

The invention belongs to the technical field of nuclear power, and particularly relates to a ground capacitance measurement method based on series capacitance and high-frequency signal injection. In order to solve the problem that a traditional signal injection method cannot accurately calculate the ground capacitance level of a power distribution network, the invention provides a ground capacitance measurement method based on a series capacitor and high-frequency signal injection. The leakage inductance of the voltage transformer is accurately measured by injecting the high-frequency signal, so that a resonance point is convenient to find during frequency sweeping, and the resonance point measured during frequency sweeping is more accurate.

The invention discloses a power frequency waveform classification method and device, a medium and equipment, and belongs to the field of waveform classification, and the method comprises the steps: obtaining preprocessed power frequency waveform data of a power transmission line, calculating various waveform features, and inputting the features into a preset cascade classifier model. The model is composed of a plurality of XGBoost binary classifiers which are cascaded in sequence, and each classifier is responsible for executing a specific binary classification task. The output result of the previous classifier is used for triggering the starting of the next classifier, or the final classification result is directly output. The cascade structure not only improves the accuracy and efficiency of classification, but also reduces the complexity of the model, and effectively solves the problem that the fault positioning power frequency of the power transmission line cannot be accurately and efficiently classified in the prior art.

The invention relates to the technical field of power system state monitoring, and discloses an insulator defect detection method and device and a storage medium, and the method comprises the steps: collecting the leakage current of an insulator, and constructing a polarity conduction screening model through power frequency phase information, so as to generate a composite current sequence which highlights the polarization attribute of an interface; analyzing the nonlinear degree of the attenuation rate of the sequence drifting along with evolution time in a multi-stage diffusion evolution time domain, and generating an interface electrochemical mass transfer composite index; utilizing the index to invert and construct an interface polarization background reference and stripping the interface polarization background reference from the composite current sequence so as to extract an abnormal discharge pulse residual error; and finally, quantizing the pulse form distortion degree of the residual error, and performing suppression normalization operation on the distortion degree by using the index to output a judgment result. According to the invention, the interference of the interface mass transfer process is effectively eliminated, and the specific detection of the pollution flashover hidden danger is realized.

The invention relates to the technical field of power equipment state monitoring, and discloses a transformer oil paper insulation frequency domain response online monitoring system which comprises an interface protection module, a modulation control module, a servo balance module and a diagnosis reconstruction module. The interface protection module extracts end screen leakage current and provides overvoltage protection; the modulation control module tracks the bus voltage phase and generates broadband modulation excitation voltage; the servo balance module generates a reverse servo current through closed loop feedback, counteracts a power frequency component in a leakage current so as to maintain a virtual ground state of a measurement node, and injects broadband excitation in a superposed manner; and the diagnosis reconstruction module synchronously acquires signals, reconstructs data in combination with time sequence information, calculates equivalent complex admittance by utilizing cross-correlation demodulation, and outputs complex capacitance and a dielectric loss factor. According to the invention, the operating voltage is used as a carrier wave, strong power frequency interference is eliminated through hardware servo, and safe online excitation is realized by matching with phase chopping, so that the difficult problem of weak broadband signal extraction is effectively solved, and combined monitoring and diagnosis are realized.

The invention relates to a load starting impact load variable working condition control method for an oil field micro-grid system, and belongs to the field of oil field micro-grids, the method comprises the following steps: starting an oil pumping unit, and when the rotating speed of the oil pumping unit is in a preset interval and the oil pumping unit operates stably, triggering a static rapid change-over switch STS and a seamless change-over switch to act; the STS switch switches a motor of the oil pumping unit from variable-frequency power supply to power-frequency power supply, in the switching process, electrical parameters of a variable-frequency circuit and a power-frequency circuit are monitored in real time, when it is judged that switching conditions are met, a switching instruction is sent out, and the PLL synchronous control technology is adopted to ensure that current and voltage transition of the motor is smooth at the switching moment. According to the method, power frequency starting can be achieved to stabilize the voltage of the micro-grid, impact on the micro-grid caused by large starting current is effectively restrained, and continuous and reliable power supply of the micro-grid is guaranteed.

The invention is suitable for the technical field of sensors, and provides a wireless current sensor, a current detection method and a computer program product, an electric field electricity taking module and a magnetic field electricity taking module take electricity from an alternating electric field and an alternating magnetic field around a to-be-detected power transmission line respectively, and provide a first direct current and a second direct current for an energy storage module respectively; a first voltage sampling value and a second voltage sampling value are respectively output; the processing module determines the electric field power and the magnetic field power of the power transmission line to be measured at the current moment according to the first voltage sampling value, the second voltage sampling value, the environment temperature value and the environment humidity value at the current moment; the current system working condition is determined according to the electric field power, the magnetic field power, the total harmonic distortion rate, the waveform flattop rate and the crest factor of the current detection signal in the current power frequency period, and the current detection module is controlled to carry out current detection based on a current detection strategy matched with the current system working condition. And high stability and current detection precision can be realized under all working conditions.

Disclosed in the present invention is a five-level bidirectional inverter, comprising a controller and a bidirectional inverter circuit. The bidirectional inverter circuit comprises a direct current (DC), an alternating current (AC) filter capacitor Cf, an AC, a high-frequency vertical bridge arm, a power-frequency vertical bridge arm, a high-frequency horizontal bridge arm, and two DC filter capacitors. The high-frequency vertical bridge arm and the power-frequency vertical bridge arm are both formed by connecting two power switching transistors in series; the high-frequency horizontal bridge arm is formed by connecting two power switching transistors back-to-back in series; two ends of the high-frequency vertical bridge arm and two ends of the power-frequency vertical bridge arm are respectively connected to positive and negative electrodes of the DC; and the controller controls the bidirectional inverter circuit to work in an off-grid inverter mode, a grid-connected inverter mode or a rectification mode. In the present invention, the output voltage is at five levels, and the output equivalent frequency is four times the switching frequency, thereby improving the conversion efficiency of the inverter, reducing the output voltage or current harmonics, and reducing the volume of filter inductors; and the modulation method in the present invention is simple, so that the design of the controller can be simplified.

The invention discloses a distribution network traveling wave head analysis and fault location method and system based on edge calculation. The method comprises the steps that S1, terminal parameters are configured on a power distribution terminal; s2, monitoring a traveling wave signal and a power frequency electrical quantity of the distribution line in real time, and starting wave recording when a traveling wave amplitude exceeds a threshold value; s3, wave recording data are screened through the power frequency electrical quantity change and the traveling wave starting sequence; and S4, carrying out wave head detection on the fault initial traveling wave recording data, carrying out section determination on the fault so as to carry out double-end distance measurement, and then carrying out correction processing on the distance measurement result of the power distribution terminal located in the fault section based on the line section parameters. According to the method, a marginal distribution calculation mode is adopted, and fault identification, wave recording screening and positioning calculation capabilities are integrated on a power distribution terminal side, so that the data communication traffic and the calculation pressure of a master station are greatly reduced, real faults and interference wave recording can be effectively distinguished, and distance measurement errors caused by wave velocity differences in a mixed line in a traditional method are overcome.

The invention discloses a partial discharge harmonic online early warning method for a cable branch box, and particularly relates to the technical field of electrical measurement and power equipment state monitoring. And a unified time base is difficult to obtain through multi-point monitoring, harmonic distortion is easy to be misjudged as discharge, and stable positioning is difficult in a topological constraint. Harmonic scene fingerprints are constructed under a unified time base, version locking is carried out, power frequency phases are re-calibrated according to the fingerprints, gating compensation is set in a non-whole frequency band domain, and joint matching is carried out by combining arrival time difference with energy attenuation under the constraint of a topological equivalent transmission matrix. And dual-threshold interlocking trigger early warning is carried out by combining the separation degree with topological consistency, so that partial discharge pulses can still be stably displayed under the change of a harmonic working condition, false alarm and caliber drift caused by harmonic waves are inhibited, reviewable positioning and executable graded early warning of branch and joint levels are realized, and the reliability of the system is improved. And the stability, comparability and implementability of field judgment are improved.

The invention discloses a totem-pole PFC circuit control method and device based on an improved SOGI-PLL, and belongs to the technical field of totem-pole PFC circuits, and the method comprises the steps: collecting the input voltage, input current and bus voltage of a totem-pole PFC circuit; synchronous phase information of the power grid voltage is obtained through an improved second-order generalized integral phase-locked loop; generating a current amplitude reference signal, and combining the current amplitude reference signal with the synchronous phase information to synthesize a current reference signal; generating a pulse width modulation signal for controlling a high-frequency switching tube; and a switching signal of the power frequency switching tube is generated based on the synchronous phase information, and the power frequency switching tube and the high-frequency switching tube are driven in combination with the pulse width modulation signal, so that the action time sequence is synchronous with the phase of the power grid voltage, and therefore, waveform tracking of the input current is realized, and current distortion at the zero crossing point is suppressed. Precise phase synchronization is realized based on the improved SOGI-PLL, totem pole PFC zero-crossing current distortion is effectively suppressed, and the power factor and waveform quality are improved.

The invention relates to the technical field of pre-diagnosis and health management, in particular to a low-voltage switch cabinet insulation safety diagnosis method based on discharge characteristic analysis, and the method comprises the steps: synchronously collecting original optical signals through a multispectral sensor array; performing energy compensation by using a multipath reflection equivalent attenuation model to generate reconstructed spectral line intensity data; determining a virtual time zero point by using an autocorrelation function and generating virtual phase analysis atlas data; and constructing an energy spectrum gravity center space coordinate in the energy spectrum feature space to extract a gravity center red shift feature quantity. According to the method, through multi-band relative attenuation rate compensation, power frequency period statistical peak value extraction and energy spectrum space gravity center mapping, the diagnosis problem that the insulation state is difficult to quantitatively evaluate due to signal distortion, reference phase loss and fuzzy characteristic evolution in a non-line-of-sight environment is solved.

The invention discloses a cable branch box power supply system and a method thereof, the cable branch box power supply system comprises a three-section surge protection device, an integrated trigger type discharge gap unit, an MOV clamping unit and a residual voltage shaping network, and is cooperated with a follow-up cut-off mechanism to inhibit surge and optimize residual voltage in stages, cut off current at a voltage zero point when the surge is attenuated and a power frequency current exists, and improve the reliability of the power supply system. Electric arc and operation overvoltage are reduced; the on-line health diagnosis module analyzes the deterioration trend of a key element through equivalent parameter injection measurement and an NTC temperature probe, and uploads data through an RS-485 / Modbus bus; the dynamic load distribution module adjusts branch current in real time; the intelligent cooperative control module integrates multiple modules to realize self-adaptive linkage; the fault isolation unit is linked with the follow-up cutoff mechanism, and triggers cutoff and sends an opening signal to an upper level when the fault isolation unit is abnormal; and the event recording module is used for storing related data and supporting USB on-site calling. According to the invention, the surge resistance, the cutoff reliability and the operation stability of the system are enhanced, and the preventive maintenance capability is improved.

The invention discloses a GIS metal particle defect detection test platform and a detection method, and relates to the technical field of high-voltage electrical equipment detection and fault diagnosis, and the platform comprises a GIS equipment module which is used for simulating an actual GIS equipment operation environment and an internal metal particle defect scene; the alternating current voltage module is used for applying processing frequency voltage to the GIS equipment module; the impulse voltage module is used for superposing impulse voltage on the basis of power frequency voltage to realize electric stress coupling; the physical vibration module is used for applying controllable mechanical vibration to the GIS equipment module, simulating impact disturbance generated by switch operation, and enabling internal metal particles to be in a suspended or moving state; the protection device is used for ensuring the effective superposition of the power frequency voltage and the impulse voltage and blocking the reverse voltage; and the detection equipment is used for monitoring the motion trail, the charge characteristic and the partial discharge signal of the metal particles in the GIS equipment module in real time so as to carry out defect mechanism analysis. According to the invention, complex working conditions in GIS operation can be truly simulated.