1095 results about "Drain current" patented technology

The invention provides a weak signal multi-module networking self-adaptive monitoring system for power transmission and transformation construction, and relates to the technical field of multi-module networking, and the system comprises a multi-mode module which is used for deploying a multi-mode sensing unit at a key monitoring point of power transmission and transformation equipment, collecting vibration, partial discharge, leakage current and environmental parameter signals, and transmitting the signals to a monitoring center; the signals are processed through packaging of an electromagnetic shielding shell and a built-in harmonic filter circuit so as to obtain original monitoring signal data; and the detection module is used for inputting the original monitoring signal data into the chaotic enhanced weak signal detection device, and extracting a fault feature vector by capturing an attractor phase diagram abrupt change and a time domain waveform threshold. Through the multi-mode sensing and self-adaptive networking technology, monitoring of power transmission and transformation weak signals and timely extraction of fault features are achieved, and the fault early warning accuracy and the self-adaptive capacity are improved.

The invention relates to the technical field of electrical performance testing, in particular to a water supply equipment electrical performance detection system based on artificial intelligence, which comprises an electrical parameter acquisition module, an energy efficiency analysis module, an insulation performance evaluation module and a comprehensive diagnosis module. According to the invention, a three-phase voltage and current root-mean-square value is dynamically calculated through a broadband current transformer and a sliding window integration method, a 50Hz fundamental component amplitude is extracted to separate power frequency and high frequency harmonic waves, a continuous period energy efficiency ratio standard deviation triggers an insulation detection threshold value, and a parameter fluctuation and insulation degradation response mechanism is established. Harmonic interference correction synchronous processing energy efficiency ratio and leakage current integration, the detection error being lower than 5%, temperature rise rate linear regression and bearing current threshold value cooperative determination, winding aging cross validation, fault misjudgment rate reduction to 26%, closed-loop detection fusion transient capture, dynamic threshold value triggering and multi-parameter diagnosis, early warning success rate reaching 92%, and positioning response being reduced to 3 seconds.

The invention provides a circuit board electrical performance test and diagnosis method, which comprises the following steps of: constructing a structured process-electrical data set by collecting process parameters such as etching time, pressing temperature, drilling precision, copper foil thickness and the like and electrical test indexes such as impedance deviation, leakage current, signal attenuation and the like; screening key process variables by adopting mutual information analysis and a maximum correlation-minimum redundancy criterion; through modeling of a three-layer causal diagram and a structural equation, quantitative influence evaluation of process parameters on electrical performance and fault types is realized; when a fault is detected, the system can automatically perform reverse reasoning, identify a main manufacturing deviation item and generate attribution diagnosis and process optimization suggestions, so that the accuracy of fault diagnosis and the pertinence of process adjustment are improved, and the fault occurrence rate is reduced and the product quality is improved.

The invention particularly relates to a leakage current testing method, device and system for an intelligent circuit breaker, and relates to the technical field of electrical safety detection. A composite signal generation and injection module; a broadband signal acquisition and conditioning module; and a line fault positioning and impedance analysis module. According to the invention, the composite signal generation module realizes the non-interference isolation injection of a leakage current signal and a high-frequency positioning signal, and guarantees the high fidelity of data through adaptive filtering, multi-channel synchronous sampling and high-precision timing. The line positioning module integrates TDR and a frequency domain impedance method, and through multi-frequency point deviation correction and topology-GIS association, the fault type is accurately identified, and the test and troubleshooting period is significantly shortened.

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.

According to the SiC MOSFET global short circuit and overcurrent protection circuit and the control method thereof provided by the invention, when a short circuit fault occurs in the SiC MOSFET, the drain current ID is more than several times of the rated current of the SiC MOSFET. When a short circuit occurs, a transistor QDZ of the short circuit detection circuit is switched on by node voltage Vr of the resistance-capacitance filter circuit, a fault signal VFAULT is converted into a low level, grid voltage VGS output by the grid control unit is gradually converted into zero voltage from negative driving voltage VEE, and soft turn-off is performed on the SiC MOSFET; when an over-current fault occurs in the SiC MOSFET, drain current ID is higher than rated current, node voltage Vo of the resistance-capacitance filter circuit lasts for a long time, the maximum value of capacitor voltage Vch of the over-current detection circuit is higher than reference voltage Vref2, a fault signal VFAULT is converted into low level, grid voltage VGS output by the grid control unit is gradually converted into zero voltage from negative driving voltage VEE, and soft turn-off is performed on the SiC MOSFET. According to the invention, high-speed short circuit and over-current fault protection of the SiC MOSFET in all inductance regions of a commutation loop can be realized.

The invention provides an endangered animal monitoring method based on a multi-mode floating gate type photoelectric synapse transistor, realizes multi-mode fusion of images (optical signals) and sounds (electric signals) by utilizing the light absorption capability of quantum dots and the high carrier mobility of a two-dimensional channel material, and belongs to the technical field of sensing, storage and calculation integration and endangered animal identification and monitoring. According to the method, a photoelectric synapse device is used as a reservoir, and input time sequence signals are respectively applied to a multi-mode fused photoelectric synapse transistor in the form of light and electric pulse. And along with the co-stimulation of light and electric pulse, the change response of source-drain current is generated, and the fusion processing of the multi-mode signal is realized. By adopting the method, a human multi-sensory fusion signal processing mode is successfully simulated, and accurate recognition under complex and changeable conditions can be realized by utilizing a mode of complementation of visual signals and auditory signals. Under an extreme environment or a high noise condition, edge processing and identification can be carried out on pictures and sounds of endangered animals, and a high-accuracy monitoring result can be obtained without a large amount of data return, so that the energy consumption is reduced and the monitoring efficiency is enhanced.

The invention provides a device for inhibiting drain-source overvoltage and overcurrent through active gate drive of a silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), aiming at solving the problem of voltage or current overshoot caused by circuit parasitic parameters in a high-speed switching process of the SiC MOSFET and simultaneously considering the switching speed and energy loss balance. According to the device, drain-source voltage vdc and direct-current bus voltage of the SiC MOSFET are collected to serve as feedback signals, and gate driving voltage and equivalent gate resistance are dynamically adjusted; in a key stage (a Miller plateau switching-on period and a voltage rising period switching-off period) of a switch transient state, a gate resistance network is switched through a logic control circuit, and suppression of drain current overshoot and drain-source voltage overshoot is realized. Simulation verification shows that the device can reduce voltage overshoot by 20%-30% and current overshoot by 25%-60%, only a single voltage feedback channel is needed, the cost is obviously lower than that of a traditional multi-signal acquisition active gate driving scheme, and the device is suitable for a high-efficiency SiC MOSFET power converter.

The invention relates to the technical field of electric power facility anomaly monitoring, in particular to a computer monitoring system anomaly monitoring method for large-scale electric power construction engineering, which comprises the following steps of: acquiring an insulator leakage current signal, a temperature signal and an ultrasonic signal, and calculating a corresponding energy gradient; calibrating the correlation coefficient of the sensor based on the physical characteristics of an insulator material, and calculating the dynamic weight according to the energy gradient, thereby achieving the dynamic weighting of a fault sensitive signal; generating a fusion reference signal through weighted summation; constructing a dynamic threshold by combining the thermal physical parameters of the equipment, the real-time signal characteristics and the environmental parameters; calculating a signal difference quantity between the original signal and the fusion signal, and if the signal difference quantity exceeds a dynamic threshold value, triggering abnormal early warning; noise influence on a single sensor is suppressed, the signal-to-noise ratio of a fusion signal is effectively improved, the problems of abnormal missing report and false report easily caused by a fixed threshold value are avoided, and the insulator abnormal detection precision is improved.

The invention provides a distribution network type lightning arrester leakage current optimization measurement method. The method comprises the steps of signal acquisition, preliminary signal denoising and preprocessing, wavelet transform signal decomposition, high-frequency noise component elimination and processing, input convolutional neural network CNN descrambling, integrated learning model optimization, output of descrambled leakage current signals, performance evaluation and result feedback. Through a multi-level processing method combining wavelet transform and a convolutional neural network, high-frequency noise in a weak leakage current signal is effectively removed, effective characteristics of the signal are reserved in the denoising process, and compared with a traditional method depending on a single signal processing technology, signal descrambling can be more accurate and effective, and the signal descrambling efficiency is improved. According to the wavelet transform signal decomposition method, the signal can be decomposed into components with different frequencies, high-frequency noise components are effectively eliminated, low-frequency and intermediate-frequency effective signals are reserved, then the convolutional neural network further improves the definition and reliability of the signal through depth feature extraction, and accurate detection of the leakage current signal is ensured.

Provided are a charging system, an electrical isolation system, a control system, and a shockwave device. The charging system is provided with at least two electrical isolation circuits, thereby improving the frequency of sending charging control signals and further improving the frequency of charging a shockwave generation apparatus. The electrical isolation system can greatly improve the dielectric strength of the electrical isolation system, reduce a leakage current on the surface of a shockwave generator, and ensure the safety performance of the shockwave generator. The shockwave device can effectively monitor the discharge energy of a shockwave emitter, thereby improving treatment safety, controllability, and working efficiency.

The invention discloses a film capacitor enabling control method and system, a medium and a program product, and the method comprises the steps: determining current sampling data and voltage sampling data of a film capacitor in a first time period; calculating an equivalent impedance sequence within a first time length, and determining distribution characteristics of impedance components under different frequencies; dividing a plurality of frequency band intervals, and calculating an impedance change rate matrix in each frequency band interval; determining energy transmission efficiency, and determining a target frequency band interval; generating a compensation coefficient, and adjusting the amplitude and the frequency by using the compensation coefficient to obtain a target sine-wave voltage; performing energizing processing on the thin-film capacitor by adopting the target sine-wave voltage within the remaining time of the energizing duration, and calculating an instantaneous power factor in real time; and when the stability of the instantaneous power factor reaches a preset condition and the leakage current is reduced below a preset threshold value, generating an enabling completion signal. According to the invention, the adaptability between the energizing effect and the actual demand of the thin film capacitor is improved, and the energizing effect is further improved.

The invention provides a capacitive equipment resistive current taking-free PT signal measurement method suitable for a lightning arrester, and relates to the technical field of capacitive equipment resistive current measurement. The method comprises the following steps: deploying a non-contact electric field coupling sensing array; acquiring a multi-channel main induction signal and an equipment high-voltage side induction electric field signal; performing cascade filtering processing to obtain a filtering reference signal; dynamically correcting the phase deviation of the filtered reference signal to obtain a calibration reference signal; collecting a leakage current signal, and separating to obtain a resistive current component; and constructing a dielectric loss factor multivariable dynamic compensation model based on the deep belief network, embedding a capacitive equipment operation duration cumulative effect factor, and updating parameters in real time through an online learning algorithm to obtain a resistive current measurement result. High-precision measurement of resistive current is realized through an advanced technology, a model is established in combination with multiple environment parameters and equipment operation duration, adaptability is improved, and long-term accurate monitoring is guaranteed through online parameter updating.

The invention provides a preparation method of a planar gate accumulation layer channel field effect transistor embedded with a 3C / 4H-SiC heterogeneous junction. The preparation method comprises the following steps: growing an (n-) 4H-SiC drift region and an (n) 4H-SiC current expansion layer (CSL) on an (n +) 4H-SiC substrate by adopting a hot wall chemical vapor deposition (HWCVD) technology; forming a (p) 4H-SiC body region and an (n) 4H-SiC layer on the two sides of the CSL by using a mask, inductively coupled plasma (ICP) etching and ion implantation methods; growing a (p) 3C-SiC region on the upper part of the inner side of each (p) 4H-SiC body region by using a mask, ICP (Inductively Coupled Plasma) etching and HWCVD (High Weight Chemical Vapor Deposition); forming (n) 4H-SiC channels on the two sides of the middle part of the CSL by using a mask and HWCVD, and forming a (p) 3C / (n) 4H-SiC heterogeneous junction with a (p) 3C-SiC region at the bottom; respectively forming an (n +) 4H-SiC source region and a (p +) 4H-SiC source region on the outer side of each (n) 4H-SiC channel by utilizing ion implantation; forming an (n +) 3C-SiC region on the outer side of each (p +) 4H-SiC source region by adopting mask, ICP etching and HWCVD, and forming an (n +) 3C / (n) 4H-SiC heterogeneous junction with the (n) 4H-SiC layer below the (p +) 4H-SiC source region; performing high-temperature annealing to eliminate defects and activate impurities; forming an oxide layer and an (n +) poly-Si gate on the top; and respectively evaporating an alloy grid electrode, a source electrode and a drain electrode to prepare the planar gate accumulation layer channel field effect transistor embedded with the 3C / 4H-SiC heterogeneous junction. The leakage current of the transistor is small and is smaller than the on-resistance (Ron, sp), and the reverse recovery time is short.

The invention belongs to the technical field of direct current monitoring, and discloses a TMR-based open-close type direct current leakage current detection device, which comprises a magnetic core, one or more pairs of TMR sensors, a secondary side feedback coil and a main control circuit, and is characterized in that the magnetic core is provided with air gaps which are oppositely arranged; the TMR sensors are symmetrically arranged in the air gap; the secondary side feedback coil is wound on the surface of the magnetic core and forms closed-loop control with the main control circuit; the main control circuit comprises an acquisition feedback circuit, a secondary side detection circuit and a main control chip, the acquisition feedback circuit acquires signals of the TMR sensor under the control of the main control chip, generates feedback current and inputs the feedback current to the secondary side feedback coil, and the secondary side detection circuit is connected between the secondary side feedback coil and the main control chip. And the main control chip collects the secondary side voltage of the secondary side detection circuit and calculates to obtain the direct current leakage current. According to the invention, direct current leakage current detection with high sensitivity, low drift and strong anti-interference capability is realized under the open-close structure, and the requirements of a modern electric power system on continuity, safety and maintainability are met.

The invention relates to the technical field of on-line health monitoring of wide bandgap semiconductor power devices, and discloses an on-line gate leakage current monitoring method and system for a GaN power device, and the method comprises the steps: extracting an average gate driving current which is within a complete switching period, an average value of instantaneous currents flowing into or out of the gate of the GaN power device; and on the basis of the average gate driving current, gate leakage current is obtained, so that online gate leakage current monitoring of the GaN power device can be carried out. The system corresponds to the method. According to the invention, the core problem that the traditional voltage detection method is insufficient in resolution and cannot realize early warning is fundamentally solved; meanwhile, a source electrode series sampling and non-intrusive signal conditioning circuit is adopted, a switch and a voltage stabilizing circuit are prevented from being introduced into a grid electrode driving loop, and therefore interference on parasitic parameters of the grid electrode loop is eliminated, and feasibility and reliability of application in a high-frequency and high-sensitivity GaN power device are ensured.

The invention relates to a power transmission line fault risk grading evaluation method based on multistage early warning, and belongs to the field of power system safety. Comprising the following steps: acquiring an insulator surface pollutant data generation matrix; extracting spatial distribution characteristics of pollutants; leakage current waveforms under different humidity are calculated; extracting a leakage current harmonic component and pulse characteristics; dividing pollution flashover risk grades; matching the maintenance strategy and generating an equipment scheduling instruction; and performing fault risk grading evaluation to generate a report. According to the method, through multi-source data fusion and dynamic modeling, accurate evaluation and preventive maintenance of the pollution flashover risk of the insulator are realized, and the safety and reliability of a power system are improved.

Disclosed in the present invention is a ground fault device end-of-life self-test system. An induction coil and a neutral coil are used for sensing and acquiring a ground fault leakage current signal of a live wire or a neutral wire. A trip device is used for cutting off the power supply to a load in the event of a ground fault by driving a solenoid by means of a thyristor which is triggered by an IC1 to turn on. A manual test button is used for manually testing the function of a ground fault device. A rectifying circuit is used for rectifying an alternating current (AC) and outputting same to a direct current, and providing the direct current to IC1 and IC2 direct current power supplies. A ground fault detection circuit is used for completing ground fault detection, and controlling the drive to trigger the thyristor to turn on or off. A ground fault self-test control circuit is used for controlling the testing of a ground fault detection function without affecting normal ground fault detection and protection functions.

The invention discloses a full-power variable-speed pumped storage unit stator winding insulation state online monitoring method, and provides a high-capacity generator unit stator winding insulation state online monitoring method which can be applied to a network side transformer neutral point ungrounded system. According to the method, an effective common-mode monitoring loop can be established, and monitoring is carried out by utilizing the third harmonic of the motor stator winding and is not interfered by the high-frequency switch harmonic of the frequency converter. In order to solve the problem that a full-power variable-speed pumped storage unit generally has large capacity and is not easy to realize online measurement, the invention provides a method for measuring on a neutral point outgoing line, which can realize online measurement of the insulation state of a stator winding when the load current is relatively large. The method is suitable for a full-power variable-speed pumped storage high-capacity unit, leakage current measurement can be carried out under the condition of large load current, and stator insulation information online monitoring is achieved.

The invention discloses an intelligent monitoring system for high-voltage power supply equipment, which belongs to the technical field of power distribution equipment monitoring and comprises three-in-one monitoring equipment including a temperature measuring device, a leakage current monitoring device and an ultrahigh-frequency partial discharge monitoring device. And data is transmitted to the wireless receiving unit through ultra-narrow-band wireless communication, and is finally summarized to a background intelligent data analysis platform, so that real-time monitoring and efficient and accurate judgment of the running state of the high-voltage equipment are realized. The system has the advantages of being high in intelligent degree, convenient to install, low in power consumption and the like, solves the problems that a traditional monitoring device is difficult to supply power, complex in wiring, unstable in data transmission and the like, and is suitable for state sensing and health management of large-scale high-voltage power distribution equipment. By using the system, field detection can be reduced, a large amount of manpower and material resources can be saved for power enterprises, the power facility management efficiency can be improved, the maintenance management level is improved, and stable operation of a power grid is ensured.

The invention discloses a method for monitoring the insulation state of a stator winding of an injection unit based on neutral point harmonic frequency sweeping. The invention provides an active online monitoring method based on harmonic injection for stator winding insulation of a full-power variable-speed pumped storage unit. A common-mode loop is constructed for a motor stator winding of a network side transformer neutral point ungrounded system through a motor neutral point grounded transformer, and therefore online monitoring of the insulation state of a motor stator is achieved. In order to solve the measurement problem of the full-power variable-speed pumped storage unit under the large-current working condition, a neutral point outgoing line current detection technology is adopted. A machine end large current interference area is avoided, monitoring is carried out on the primary side of the grounding transformer, transmission errors are avoided, and the measurement precision and reliability of insulation monitoring signals are remarkably improved. According to the invention, harmonic injection is carried out by avoiding an inherent common-mode component of a unit, a monitorable leakage current signal is enhanced, and the accuracy of insulation equivalent capacitance calculation is ensured.

The invention discloses a thyristor type device leakage current monitoring method and circuit and a power electronic device.The method comprises the steps that in response to a system turn-off instruction, a first control signal is sent to a device turn-off module; the device turn-off module is used for conducting a turn-off branch of the thyristor device according to the first control signal; acquiring a leakage current sampling signal from a leakage current monitoring module; the leakage current monitoring module is used for converting the gate current of the thyristor device into a leakage current sampling signal; and generating a leakage current monitoring result based on the leakage current sampling signal. According to the invention, real-time and accurate measurement of the leakage current can be realized on the premise of not influencing system operation.

The invention relates to an on-line monitoring method for the on-off state and abnormal behavior of a synchronous rectification MOSFET of a power system. According to the method, a drain-source voltage VDS signal and a drain current Isd signal of a synchronous rectification MOSFET are collected in the working process of a system, and on-line monitoring is conducted on the on-off state and the abnormal state of the MOSFET. The method specifically comprises the following steps: conducting state monitoring: when VDS is smaller than or equal to a conducting judgment threshold value, judging to be conducted, and otherwise, judging to be turned off; monitoring an oscillation state, and judging switch oscillation when the VDS generates multiple complete oscillations in a set time window; early turn-off monitoring is carried out, early turn-off is judged according to whether I sd is higher than a threshold value or not during turn-off in the DCM mode, and early turn-off is judged according to the current descending trend and zero intersection point deviation in the CCM mode; withstand voltage monitoring: when the VDS transient peak value exceeds the rated withstand voltage or margin of the device, determining that the device is unsafe; and mis-opening monitoring: in the DCM mode, when the VDS is close to the opening threshold value during the logic turn-off period, determining that the mis-opening risk exists. The method can improve the reliability of the power supply system.

The invention provides a leakage current testing method and system based on a low-frequency EIS and a transverse current pulse, and relates to the technical field of leakage current testing. The method comprises the following steps: firstly, determining use information and low-frequency EIS test parameters of a target battery to be tested, then testing the battery by using electrochemical working equipment according to the parameters, obtaining impedance data under different frequencies, and further obtaining first dynamic capacitance information. And controlling the power supply equipment to apply a preset transverse pulse current to the battery, determining a voltage variation cut-off condition, continuously monitoring the voltage variation, and recording the test time variation when the cut-off condition is reached. And finally, the leakage current value of the battery is determined by integrating the first dynamic capacitance information, the transverse current pulse current, the test time variation and the voltage variation. Compared with a traditional method, the leakage current value can be obtained only by applying the direct current once after the low-frequency EIS test without changing the magnitude and the duration time of the current for many times, the test process is simplified, the test efficiency is improved, and the leakage current value can be determined more accurately.

The invention discloses a generator stator winding single-phase earth fault positioning method, system and device and a medium, and the method comprises the steps: enabling three phases of a generator stator winding to be connected in series end to end to form a series loop; low-frequency voltage pulses are injected into the three-phase winding, and a fault phase is determined by comparing symmetry damage characteristics of tail-end current by adopting a tail-end current vector analysis method; injecting a low-frequency voltage pulse into the current phase winding, detecting the current difference between the head end and the tail end of each parallel branch, identifying a branch with abnormal leakage current by combining a leakage current characteristic analysis method, and determining a fault branch; establishing a high-frequency distribution parameter model, and performing high-frequency voltage pulse injection positioning for multiple times to obtain three independent high-frequency pulse positioning results; and performing weighted fusion on the three independent high-frequency pulse positioning results, and performing optimization by using an intelligent optimization algorithm to obtain an optimized single-phase earth fault position. According to the invention, the accuracy and rapidity of fault diagnosis and positioning can be improved.

A leakage current detection circuit and a leakage current protection circuit are disclosed. The leakage current detection circuit includes a mutual inductance module, an excitation module, a signal processing module, a feedback self-check module and a calculation module. The mutual inductance module includes a magnetic core, a first winding and a second winding. The excitation module is configured for producing an excitation current in the first winding. The signal processing module is configured for processing the output voltage signal of the first winding and outputting a processed signal, and the voltage signal corresponding to the excitation current is filtered out of the processed signal. The feedback self-check module includes a feedback circuit and a self-check circuit. The calculation module is configured for analyzing the leakage current according to the processed signals and outputting the self-check signal in the self-check mode.

A high-frequency resistant ground fault circuit interrupter (HF-GFCI) with self-test and end-of-life detection is disclosed. The invention incorporates a noise-resistant fault detection circuit, an auto-test module, and an end-of-life shutdown mechanism to ensure reliable protection. The device minimizes false tripping due to high-frequency noise and enhances safety through continuous self-monitoring. Experimental validation confirms improved immunity to leakage currents and transient voltage disturbances. The HF-GFCI also provides an LED circuit having dual functionality: an LED indicator circuit and neutral to ground detection on the load side of the HF-GFCI.

The invention discloses a transformer substation AC power supply residual current detection method and device, and the method comprises the steps: carrying out the vector synthesis of three-phase current data and zero line current data, forming a current difference sequence, exporting a residual current reference curve, and carrying out the fluctuation analysis of the residual current reference curve, and judging the leakage characteristics. After effective leakage features are formed through harmonic elimination, dominant frequency components are locked through frequency spectrum decomposition; calibrating a leakage type identifier according to the dominant frequency component and forming segmented leakage distribution; a deviation degree is formed by means of segmented leakage distribution and residual current reference curve deviation analysis, a correction deviation value is formed through load fluctuation compensation, and a standard exceeding coefficient is formed according to threshold value comparison to detect abnormal nodes to form hidden danger data; establishing a judgment rule based on the hidden danger data and the leakage type identifier to form a detection evaluation index; and executing path tracking on the detection evaluation indexes to form leakage position information, forming a disposal priority through intensity analysis to generate a residual current detection report, and realizing leakage current classification identification and self-adaptive evaluation.

The invention discloses a zinc oxide arrester aging fault monitoring method and system based on fifth harmonics, and belongs to the technical field of high-voltage electrical equipment protection. The method comprises the following steps: acquiring the total leakage current of the zinc oxide arrester under different applied voltages; the different applied voltages comprise pure sine wave voltages and voltages with harmonic components; according to the total leakage current, obtaining leakage resistance current and third harmonic and fifth harmonic thereof; comparing the total leakage current, the leakage resistance current, the third harmonic and the fifth harmonic to obtain a monitoring index of the aging fault of the zinc oxide arrester; and obtaining a monitoring result of the aging fault of the zinc oxide arrester according to the monitoring index of the aging fault of the zinc oxide arrester and the applied voltage. According to the invention, the harmonic component is added into the applied voltage to simulate the harmonic interference of the power grid voltage, and the leakage current of the lightning arrester is analyzed to monitor whether the aging fault of the zinc oxide lightning arrester occurs.

The embodiment of the invention relates to the technical field of current limiting, in particular to a current limiting device which comprises a first transistor, a second transistor, a compensation element and a voltage balance circuit. A drain electrode of the first transistor and a drain electrode of the second transistor are connected with a power supply, a source electrode of the first transistor is connected with a load, a source electrode of the second transistor is connected with a first end of the compensation element, and a grid electrode of the first transistor is connected with a grid electrode of the second transistor. The voltage balancing circuit is connected between the second end of the compensation element and the source electrode of the first transistor. Therefore, the maximum current actually passing through the first transistor is the drain current corresponding to the drain-source voltage for converting the first transistor from the linear region to the saturation region under the action of the preset maximum gate voltage, and the power supply and the load which can normally work under the action of the maximum current are selected to be matched with the current limiting device for use. The situation that current passing through the first transistor is too large can be reduced, and the possibility that a power supply and a load are damaged is reduced.