299 results about "Ground current" patented technology

The invention relates to the field of cable monitoring, in particular to a high-voltage cable running state comprehensive monitoring method based on a TMR magnetic sensor. According to the method, firstly, a TMR magnetic sensor is adopted to collect sheath current and partial discharge pulse signals of a cable joint grounding wire, then amplification, filtering and AD change are carried out, Fourier transform is carried out, and low-frequency signals and high-frequency signals are separated out; carrying out frequency spectrum analysis on the high-frequency signal, preliminarily judging whether a discharge defect exists or not, carrying out Fourier inversion on the low-frequency signal, evaluating a grounding state and an insulation health state of a cable sheath, carrying out Fourier inversion on the high-frequency signal, and carrying out partial discharge fault type analysis in combination with a time domain partial discharge pulse signal and a power frequency current phase; and finally, comprehensively evaluating the operation state of the high-voltage cable by analyzing the grounding current of the sheath and the related parameters of partial discharge. According to the invention, the hardware cost is reduced, the system design and installation complexity is simplified, and the accuracy of partial discharge fault type identification is improved.

The provided are a method, system, and medium for active arc-extinguishing voltage-current conversion in distribution networks. The method includes: detecting a single-phase-to-ground fault in the distribution network and identifying the target faulty phase; injecting compensating currents into the target faulty phase to reduce its voltage; measuring the residual current at the fault point during the injection of compensating currents and the zero-sequence voltage of the target faulty phase; determining a critical zero-sequence voltage threshold based on the residual current at the fault point and assessing whether this critical value exceeds the present zero-sequence voltage; if so, ceasing the injection of compensating currents into the target faulty phase and instead injecting active arc-extinguishing currents at the neutral point of the distribution network to mitigate ground currents at the grounding points of the distribution network. The objective is to enhance the applicability of arc-extinguishing methods for ground faults in distribution networks.

The invention relates to a power cable insulation state real-time monitoring and alarm device, and belongs to the technical field of power equipment state monitoring. Comprising a multi-source sensing unit which is installed at a cable body and a joint; the edge computing terminal is fixed in the cable well or the ring main unit; and the cloud early warning platform receives the processing data and outputs an alarm instruction. According to the invention, multi-parameter deep fusion is realized, four-dimensional monitoring of grounding current, temperature, partial discharge and humidity is initiated for the first time, and limitation of a single parameter is broken through; and an insulation health index IHI is proposed, and the insulation deterioration degree is quantitatively evaluated. According to the method, tan delta and IHI are calculated on site through an edge-cloud collaborative architecture edge terminal, so that the data transmission quantity is reduced; the cloud dynamic threshold value is adjusted, and the alarm accuracy is improved. According to the invention, intelligent early warning mechanism three-level alarm linkage protection equipment is arranged; and the self-calibration function ensures long-term reliability.

The invention discloses a power distribution network grounding fault research and judgment analysis method, relates to the technical field of power distribution network fault analysis, and solves the technical problem that fault analysis is not accurate and deep enough due to the fact that fault features in a neutral point grounding complex fault scene cannot be comprehensively considered. According to the method, single-phase grounding fault models of a neutral point ungrounded system, an arc suppression coil grounded system and a small resistor grounded system are respectively constructed, grounding current, phase voltage and neutral point voltage expressions under the models are detailedly deduced, and characteristics of voltage and current before and after a fault point in the steady-state and transient-state processes are deeply analyzed; the method comprehensively considers various complex fault scenes, can more accurately grasp essential characteristics of faults in different grounding modes, and provides a more comprehensive and accurate basis for fault diagnosis and processing.

The invention discloses a power transmission line tower grounding resistance measuring method and system, and relates to the technical field of high-voltage power transmission, and the measuring method comprises the following steps: transmitting a first electric signal to a coupling injection module, and enabling the coupling injection module to synchronously inject a same second electric signal to two lightning conductors of a power transmission line tower; acquiring voltage signals and current signals at the second electric signal injection positions of the two lightning conductors; and calculating the grounding resistance of the power transmission line tower according to the collected voltage signal and current signal. The same second electric signal is synchronously injected to the two lightning conductors through the coupling injection module, and the ring current between the two lightning conductors is greatly weakened, so that the ground current component can be better extracted, the ground resistance value can be quickly and accurately obtained, the measurement efficiency is improved, errors caused by manual operation are reduced, and the measurement accuracy is improved. The measurement mode does not need to insert an auxiliary grounding electrode and lay a long-distance lead, and is convenient to operate and wide in application range.

The invention discloses a high-voltage cable grounding current abnormity monitoring system, which belongs to the technical field of electric power facilities and comprises an inspection acquisition module, an association analysis module, a collaborative reasoning module and a self-optimization module. The inspection acquisition module is used for synchronously acquiring multi-source monitoring parameters and acquiring position information so as to generate a grounding parameter matrix; the association analysis module is used for screening suspected defect types, dividing a local overheating area, performing overheating cause judgment, constructing a coupling association matrix of a multi-physical field, performing evolution stage judgment in combination with historical data, and generating a preliminary mechanism hypothesis in combination with credibility rating; the collaborative reasoning module is used for constructing a dynamic knowledge graph and a constraint prediction network, constructing a collaborative reasoning mechanism based on a two-way real-time interaction channel, performing preliminary reasoning, and dividing early warning levels in combination with comprehensive confidence so as to perform operation and maintenance feedback; and the self-optimization module is used for carrying out directional iteration on the double engines by utilizing manual feedback and carrying out cross-line migration optimization according to different lines.

The invention provides an on-line monitoring system and method for the grounding current of a transformer iron core, and belongs to the field of data processing, and the system comprises a magnetic adsorption type dual-channel current sensor which is used for synchronously collecting a transformer iron core grounding current channel signal and a transformer clamp grounding current channel signal; the self-adaptive signal preprocessing module is used for carrying out self-adaptive differential processing through a self-adaptive differential coefficient and carrying out variable gain adjustment and self-adaptive filtering; the multi-dimensional feature extraction module is used for performing multi-dimensional signal feature extraction on the purified grounding current signal to obtain a multi-dimensional feature parameter set; the feature fusion module is used for performing constraint fusion on the multi-dimensional feature parameter set based on the corrected iron core eddy current loss physical model, and generating a comprehensive health evaluation index through an adaptive weight adjustment mechanism; and the intelligent diagnosis module is used for carrying out transformer iron core fault type identification, health state evaluation and trend prediction according to the comprehensive health evaluation index and the multi-dimensional characteristic parameter set to obtain a transformer iron core state monitoring result.

The invention provides a power converter. A direct-current arc detection device arranged in the power converter comprises a first current induction device, a second current induction device and a controller. The first current sensing device is used for sensing the current change of the positive cable and outputting a first voltage signal, the second current sensing device is used for sensing the current change of the negative cable and outputting a second voltage signal, and the controller is used for adjusting the gain ratio between the first voltage signal and the second voltage signal. Therefore, the gain ratio of positive and negative cable sampling signals can be independently adjusted according to the asymmetric working condition of positive and negative cable loops, so that the optimal differential mode signal suppression effect is achieved, the interference of alternating current to ground current on direct current arc detection is reduced to the greatest extent, and the false alarm probability of direct current arc detection is reduced.

The invention discloses a comprehensive monitoring and early warning method and system for a transformer, and relates to the field of transformer monitoring, and the method comprises the steps: collecting the state data of a target transformer in real time, the state data comprising oil chromatography data, a partial discharge signal, a grounding current, local temperature data and a local vibration signal; the current state data is preprocessed; performing multi-angle evaluation on the state of the target transformer according to the preprocessed current state data; if the state of the target transformer obtained through evaluation from at least one angle is abnormal, performing early warning on each abnormal state of the target transformer; accurate monitoring and early warning of the state of the target transformer are achieved, and the problems that an existing transformer monitoring method is low in monitoring precision and insufficient in fault early warning capacity are solved.

The invention relates to a ring main unit intelligent detection and fault early warning method and system. The method comprises the following steps: deploying an ultrahigh frequency sensor, an infrared thermal imager, an ultraviolet sensor and a high-frequency current transformer, and synchronously acquiring multi-modal data such as partial discharge, temperature distribution, corona discharge and grounding current of the ring main unit; carrying out feature extraction on the collected data, wherein the feature extraction comprises a time-frequency statistical feature and a temperature-load correlation feature of the partial discharge signal; the Dempster-Shafer evidence theory is utilized to carry out fusion calculation on the multi-source feature evidence, and confidence coefficients for insulation degradation, poor contact, arc faults and other fault types are obtained; arc fault prediction is carried out in combination with a long-short-term memory network model; and finally executing a grading early warning strategy according to the fault confidence. The problems of low detection reliability and fault early warning lag of a single sensor are solved, early accurate diagnosis and predictive maintenance of the insulation fault of the ring main unit are realized, and the operation safety and reliability of power equipment are remarkably improved.

The utility model discloses a grounding detection device for an auxiliary circuit of a railway locomotive. The grounding detection device comprises a plurality of loads, an A / D converter, a judging device and a plurality of current detectors, the input end of each current detector is connected with the shell of the corresponding load and is used for acquiring the grounding current leaked from the shell of the load; the input end of the A / D converter is connected with the output end of the current detector, and the A / D converter is used for converting the grounding current into a digital signal from an electric signal; the judger is connected with the output end of the A / D converter and comprises comparators in one-to-one correspondence with the A / D converter, each comparator is internally provided with a threshold value, the comparators are all compared with the corresponding digital signals, when the input digital signals are not larger than the threshold values, the comparators output first signals, and when the input digital signals are larger than the threshold values, the comparators output second signals. And the comparator outputs a second signal so as to simplify the process of ground fault detection and improve the easiness of load detection.

The invention provides a defected ground-based broadband high-isolation MIMO (Multiple Input Multiple Output) mobile phone antenna. Each face-to-face inverted-F antenna pair is connected with an inverted-L branch knot; lumped capacitors are arranged at the joints of the radiation arms and the vertical lines where the feeding points are located; 2N linear slots are formed in the feeding points of the N dual-port antenna pairs on the edge of the metal ground; a T-shaped gap is formed in the middle position of the two antennas of each dual-port antenna pair; an antenna pair gap is formed between the two dual-port antenna pairs on the same side; the feed branch knot is printed in the linear slot, and the tail end of the feed branch knot is provided with a lumped capacitor. According to the invention, the distribution of floor current is changed through the T-shaped gap, and the decoupling characteristic of the MIMO mobile phone antenna is realized. By loading the inverted L branches on the inverted F antenna, introducing the coplanar waveguide structure and loading the lumped capacitor, the working bandwidth of the MIMO mobile phone antenna is effectively widened.

The invention belongs to the technical field of power protection, and particularly relates to a station transformer grounding current synchronous synthesis method and system, and the method comprises the steps: carrying out the grouping according to the number of a station transformer, synchronously collecting the grounding branch current of each station transformer to obtain an original signal, carrying out the double identification, and carrying out the homologous copying; generating two paths of independent signals of frequency detection and phase calibration; frequency detection signals are grouped according to double identifications, the independent actual frequency of each station transformer is obtained after frequency detection processing, and a same-frequency sine dynamic reference signal is generated based on the independent actual frequency; performing phase alignment and compensation on the phase calibration signal and the corresponding reference signal according to the double identifiers to obtain a calibrated signal; according to the method, the phase calibration reference of each station transformer is completely matched with the actual frequency of the station transformer, the reason of phase reference dislocation caused by frequency fluctuation is eliminated from the source, and the accuracy of synthesizing the total grounding current in the station is improved.

A method and insulation monitoring arrangement for insulation monitoring of an electric installation operated using a supply direct voltage and has a first insulation resistance between the positive active conductor and ground and a second insulation resistance between the negative active conductor and ground as well as a functional grounding between the negative active conductor and ground by a ground resistance. The method involves measuring a ground current, which flows in the path of the functional grounding, by means of a DC measuring device; measuring the supply direct voltage by means of a voltage measuring device; computing the first insulation resistance from the supply direct voltage divided by the ground current by means of a computing unit; the condition is valid during operation of the electric installation that the second insulation resistance being at least 100 times greater than the ground resistance.

The invention relates to the field of power system equipment detection, in particular to a residual magnetism measuring device and method for a large power transformer. The residual magnetism measuring device for the large-scale power transformer comprises the large-scale power transformer, a high-voltage bushing, a high-voltage neutral point bushing, a low-voltage bushing, an iron core outgoing line bushing, a first capacitor, a second capacitor, a detection impedor, a partial discharge instrument and a large-current generator, the capacitance of the first capacitor is 30pf-40pf and is matched with the capacitance of a transformer iron core, and the capacitance of the second capacitor is 300pf-400pf and is 10 times proportional to the capacitance of the first capacitor; the method comprises the following steps: carrying out a long-time induction withstand voltage and partial discharge test after a conventional test, measuring discharge amounts Q1, Q2 and Q3 at 0.5, 1 and 1.5 times of rated voltages, judging residual magnetism according to the difference value of the discharge amounts and an iron core grounding current, and if the residual magnetism exceeds the standard, magnetizing and demagnetizing by using a large current generator at the frequency of 150Hz. The method has the advantages that the residual magnetism is measured and evaluated in time, equipment faults are avoided, operation is easy and convenient, and adaptability is high.

The invention relates to the technical field of wind driven generators, in particular to a system for reducing generator shaft current damage and a working method.The system is characterized in that a generator spindle is connected with a generator shell through at least one insulating bearing, and at least one grounding ring is further arranged on the generator spindle; the grounding ring is grounded through a carbon brush and a grounding wire which are connected in sequence; the grounding wire is provided with a current transformer, and the current transformer is used for obtaining grounding current data and transmitting the grounding current data to the data processing end. And the data processing end is used for predicting working state data of the insulating bearing based on the grounding current data, the data of the environment where the fan is located, the fan operation data and the insulating bearing data, and evaluating whether a shaft current risk alarm is sent or not based on the working state data of the insulating bearing. By monitoring and evaluating the working state of the insulating bearing of the system, operation and maintenance personnel can master the working state of the insulating material of the insulating bearing at any time, and the situation that equipment is damaged by shaft current due to failure of the insulating material is avoided.

The invention discloses a cable dielectric loss monitoring method and system based on leakage current separation, and the method comprises the steps: collecting the grounding current and phase current of three phases of a cable, and collecting the space voltage of an intermediate phase; calculating lead angles of the grounding current and the phase current based on the grounding current, the phase current and the space voltage; in any period, separation of induced current is carried out based on the lead angles of the grounding current and the phase current at two different moments, and the phase angle of the leakage current is determined; and calculating a dielectric loss angle tangent value of each phase based on the phase angle of the leakage current. According to the method, the dielectric loss of the cable can be monitored in real time under the condition of normal operation of the cable, and the dielectric loss angle tangent value of the cable can be obtained more accurately by separating the induced current from the leakage current and calculating the phase difference between the leakage current and the space voltage, so that the aging state of the cable can be evaluated more accurately, and the service life of the cable is prolonged. And the safety and the reliability of the power system are improved.

The invention discloses a method and a system for diagnosing defects of a sheath grounding system under resonance voltage resistance of a power transmission cable. The method comprises the following steps: installing a sheath grounding current acquisition system; sequentially carrying out main insulation resonance voltage withstanding tests on three phases of the power transmission cable, and synchronously recording a grounding current waveform of a metal sheath by adopting a current acquisition system when each phase is subjected to voltage withstanding; processing the grounding current waveform by adopting a signal processing algorithm, and extracting a resonance component; and constructing a defect diagnosis matrix according to the resonance component, calculating a deviation between the defect diagnosis matrix and a standard matrix as a defect characterization value of the cable sheath grounding system, and obtaining a defect diagnosis conclusion of the sheath grounding system under the resonance withstand voltage of the power transmission cable. According to the method, the grounding current waveform of the metal sheath is synchronously acquired and analyzed in the main insulation resonance voltage withstand test of the three-phase cable, the resonance component is extracted, accurate identification of the defect is realized based on deviation calculation of the defect diagnosis matrix, and the detection sensitivity and the diagnosis reliability of the latent defect of the sheath grounding system before the cable is put into operation are improved.

The invention relates to a three-dimensional multi-source stray current interference characteristic analysis and identification method based on wavelet analysis. When a buried pipeline is subjected to electrical interference of different interference sources (such as high-voltage transmission line current, high-voltage direct-current grounding electrode grounding current, electrified railway and high-speed railway current, urban rail transit current and natural environment such as tidal interference current), the buried pipeline is subjected to electrical interference. And identifying and analyzing the pipe-to-ground potential and alternating current voltage fluctuation characteristics (amplitude characteristics and frequency characteristics) under stray current interference, judging the influence of interference sources on the safety and stability of the buried steel pipeline, solving the problems of analysis, identification and processing of multiple interference sources in the existing complex environment, improving the monitoring and treatment level of the interference sources of the buried steel pipeline, and improving the safety and reliability of the buried steel pipeline. Safe and reliable operation of the pipeline is ensured.

The invention discloses a cable fault monitoring and early warning method and system, and relates to the technical field of fault monitoring. The method comprises the steps that cable operation state parameters and environment parameters are collected in real time through a distributed sensor array, and the cable operation state parameters comprise cable temperature, three-phase current, partial discharge signals, insulation resistance, grounding current and mechanical vibration amplitude; the environment parameters at least comprise temperature and humidity corresponding to a cable laying environment; preprocessing the cable operation state parameters and the environment parameters, and generating a standardized feature matrix based on preprocessed multi-source data; inputting the standardized feature matrix into a pre-trained fault prediction model for processing to obtain a fault type and a fault risk index corresponding to the current operation state of the cable; and triggering an early warning mechanism according to the fault type and the fault risk index, and outputting corresponding fault position information.

The invention discloses a component separation calculation method, system and device for grounding current of a high-voltage alternating-current submarine cable and a medium. The component separation calculation method comprises the steps that current transformers are additionally arranged on submarine cable bodies at the head end and the tail end of an on-site high-voltage alternating-current submarine cable, a metal sheath grounding wire and an armored grounding wire; acquiring the current monitoring quantity flowing through the current transformer; performing vector calculation on the current monitoring quantity to obtain submarine cable core current vectors, metal sheath grounding current vectors and armor layer grounding current vectors at the head end and the tail end; vector calculation is carried out on the current vectors to obtain capacitance current components and electromagnetic induction current components of metal sheath grounding current and armoring grounding current, and the capacitance current leakage proportionality coefficient of the metal sheath and the armoring and the electromagnetic induction current proportionality coefficient of a grounding loop are calculated by further combining the submarine cable core current vectors; therefore, the grounding loop state of the metal sheath and the whole armored wire of the submarine cable and the main insulation and sheath external insulation state of the submarine cable are monitored.

The invention discloses a method for supporting high-frequency AC / DC component acquisition in core grounding current monitoring, which belongs to the technical field of transformers and comprises the steps of system initialization and communication establishment, continuous sample acquisition, period preprocessing and frequency spectrum and DC component calculation. The technical problem of accurately collecting and analyzing the high-frequency harmonic component and the direct-current component of the grounding current of the iron core at the same time is solved, the dual-channel sampling and digital signal processing technology is combined, on the basis of calculating the total current and the power frequency component, multi-dimensional monitoring and intelligent analysis of the running state of the transformer are achieved, and the fault diagnosis accuracy of the transformer is improved. According to the invention, various industrial scenes can be covered, missing detection of potential faults is avoided, and the fault early warning capability and the operation state judgment precision are improved.

The invention provides a current sampling system of a common-power power ground and a multi-channel solid state power controller, and relates to the technical field of electronics, and the current sampling system of the common-power power ground comprises a plurality of sampling modules, a corresponding number of switch modules and an MCU. And the ith sampling module is matched with the ith switch module to sample the ith load current. And the other end of the load is connected with the positive electrode of the power supply through the switch module. The sampling unit of the sampling module is connected in series between the switch module and the positive electrode of the power supply. The sampling reference end of the sampling module and the grounding end of the MCU are connected with the negative electrode of the power supply. The MCU controls the conduction state of the switch module, the sampling module samples the load current when the switch module is conducted, converts the load current into a voltage signal and outputs the voltage signal to the MCU, and the current sampling circuit solves the problems that a current sampling circuit in the related technology is high in cost and large in size.

A method for estimating the insulation resistance of power equipment in an uninterruptible state without using a sound wave signal is provided. [Solution] The method for estimating the insulation resistance of electric power equipment according to the present invention includes the steps of: (a) obtaining measured target data, which is the actual measured value of either the ground current value when the target electric power equipment, which is an epoxy-molded electric power equipment to be measured, is in a live-line state, or the electromagnetic wave intensity emitted from the target electric power equipment in a live-line state; (b) calculating a measured gradient value corresponding to the gradient of the rising edge of the measured target data; (c) reading out correlation information between the gradient of the target data recorded in advance and the surface insulation resistance value of the epoxy-molded electric power equipment; (d) deriving a surface insulation resistance value corresponding to the measured gradient value based on the correlation information; and (e) determining an estimated value of the surface insulation resistance of the target electric power equipment based on the surface insulation resistance value derived in step (d).

The invention discloses a load power control circuit and device. The circuit comprises a microcontroller module and one or more controlled modules. The controlled module comprises a controlled load and an MOS switch chip used for current detection, a current output pin of the MOS switch chip and one end of the controlled load are both connected with the input end of the microcontroller module, a control pin of the MOS switch chip is connected with the output end of the microcontroller module, the other end of the controlled load is grounded, and the output end of the microcontroller module is grounded. The current output pin outputs a current detection signal; the microcontroller module generates and sends a PWM control signal to the MOS switch chip according to the current detection signal and the voltage signal; and the MOS switch chip performs power control on the controlled load according to the PWM control signal. The load power control circuit can be compatible with most load working environment control conditions without introducing an additional current or voltage detection circuit, the circuit complexity of system peripherals is greatly reduced, and the load power control circuit has the characteristics of high precision, simplicity, high reliability and the like.

The invention discloses a transformer iron core insulation fault distinguishing method based on electromagnetic acoustic cross-modal fusion, which comprises the following steps: acquiring iron core grounding current, UHF electromagnetic signals and acoustic signals, fusing the acquired iron core grounding current, UHF electromagnetic signals and acoustic signals to obtain fusion features, processing the UHF electromagnetic signals and acoustic signals to obtain a transformer iron core insulation fault distinguishing result, and distinguishing the transformer iron core insulation fault distinguishing result. And respectively obtaining a final fault coordinate and an acoustic positioning coordinate, carrying out signal-to-noise ratio weighted fusion on the final fault coordinate and the acoustic positioning coordinate to obtain a fault three-dimensional coordinate after final fusion, processing the fusion feature and the fault three-dimensional coordinate after final fusion, and outputting a final diagnosis report. The cross-modal attention mechanism is introduced, the purified iron core current, the UHF electromagnetic signal and the acoustic signal are deeply fused, the iron core and insulation fault distinguishing accuracy is remarkably improved, and the fault diagnosis precision and stability are enhanced.

The invention provides a current-sensitive resonance eliminator driven by grounding current, and belongs to the technical field of grounding protection. The current-sensitive resonance eliminator is used for being connected between a neutral point of a voltage transformer of a distribution network system and the ground, and is structurally characterized in that a high-voltage lead, a circuit board, an electromagnetic switch and a low-voltage connecting line are electrically connected in sequence from top to bottom and are arranged in an inner cavity of an insulating sheath, the low-voltage connecting wire is led out from the tail of the electromagnetic switch; the high-voltage lead is connected with a wiring terminal of a neutral point of the voltage transformer The low-voltage wire holder is sleeved at the bottom of the insulating sheath; the low-voltage connecting wire is connected with the grounding end through the low-voltage wire holder; a current-sensitive resistor is arranged in the circuit board; when the zero-sequence current of the neutral point of the system is increased suddenly, the resistance value of the current-sensitive resistor is increased suddenly to reduce the loop current; an electromagnetic coil in the electromagnetic switch is connected with a low-voltage connecting line, the electromagnetic switch is driven to be disconnected when grounding current large enough flows through the electromagnetic coil, and the normally-closed state is automatically recovered after a safe duration.

The invention provides a transformer core clamp grounding current monitoring and dynamic suppression method, and belongs to the technical field of transformers, and the method comprises the steps: collecting high-precision real-time data through arranging a plurality of uniformly-distributed magnetic flux measurement points on a current sensor, constructing a multi-dimensional data set in combination with the environment temperature, humidity and load change conditions, and carrying out the dynamic suppression of the grounding current of a transformer core clamp; feature fusion and prediction analysis are carried out by using a UNet architecture-based dynamic suppression prediction model, model parameters and hardware equipment configuration are adaptively adjusted through a gating weighting function according to a confidence evaluation result, and an optimal control parameter adjustment value is calculated by using a current control optimization function; continuous optimization of a control strategy is realized through iterative calculation and closed-loop feedback, and finally accurate dynamic suppression control is executed by using a power electronic device, so that the technical problem that accurate dynamic suppression of the grounding current of the transformer core clamp is difficult to realize in a complex and changeable environment is solved.

A method and a system for identifying and locating sheath-to-ground fault at any arbitrary locations in a cross-bonded, single point grounded at the beginning, single point grounded or at the end at the middle, and two point grounded power cable during online condition. The system comprises a circuit having a major section of high voltage cross-bonded cable having 3 phases R and three minor sections, which interconnected with SVLs in the link box to form three loops, three-phase source voltages, and loads of each phase. The metallic sheath of each phase is grounded at the grounding box through grounding resistances. A current measuring unit measures the sheath current from this grounding resistance. This measured current is analyzed to identify and localize the inception of SG fault in a CB cable.

The invention relates to the technical field of electrical safety, and discloses a current monitoring and shielding leakage response method and system for SNELPD water immersion protection. According to the invention, the original current waveform is monitored in real time, so that the grounding state characteristic quantity is acquired according to the grounding current waveform data and the leakage current waveform data, and the final potential offset and the potential trend characteristic quantity are analyzed from the shell potential waveform, so that the insulation resistance change caused by water immersion can be captured earlier and more sensitively; then, a coupling mechanism and an evolution law between current and potential characteristics are mined, a comprehensive risk index is obtained, high-risk coupling states such as grounding efficiency reduction and potential accelerated drifting are accurately captured, the problem that in the prior art, multi-parameter internal relevance and a diagnosis blind area of a co-evolution law cannot be revealed is solved, and the diagnosis accuracy is improved. The accuracy and the reliability of early recognition of '0 potential' damage and shielding leakage risks caused by soaking of the SNELPD equipment are remarkably improved.