1068 results about "Current amplitude" patented technology

The invention discloses a fault ride-through hierarchical control method for a network-constructed converter, and the method comprises the steps: introducing a virtual resistor formed by fault current negative feedback into the voltage and current inner loop control of the network-constructed converter based on VSG control through a current inner loop dynamic amplitude limiting control layer after the converter enters a fault ride-through state, the size of the virtual resistor is adjusted in real time along with the amplitude of the fault current so as to carry out dynamic current limiting control on the virtual resistor; and the power outer loop dynamic compensation control layer dynamically adjusts an active power instruction value and a reactive power instruction value of the network construction type converter based on VSG control during the fault ride-through period according to the voltage drop degree of the power grid after the converter enters the fault ride-through state. And respectively performing active-frequency control and reactive-voltage control based on the active power instruction value and the reactive power instruction value. In addition, the method also comprises a state coupling and parameter self-adaption module. According to the method, the GFM converter can have better dynamic performance in the fault recovery stage.

The present invention relates to the technical field of power system relay protection, in particular to a power distribution network single-phase short-circuit protection method based on characteristic current adaptive injection. The method comprises: collecting a voltage of a power distribution network bus and characteristic frequency currents of feeder outlets; when a zero-sequence voltage in the power distribution network bus is detected to exceed the limit, according to a relationship between the voltage of the power distribution network bus and a threshold voltage, calculating a photovoltaic injection characteristic frequency current control reference value, and photovoltaic active power and reactive current control reference values; latching a control outer loop of a photovoltaic inverter, switching the photovoltaic active power and reactive current control reference values, setting the injection characteristic frequency current control reference value, and starting photovoltaic characteristic current adaptive injection control; and comparing the amplitudes and phases of the characteristic frequency currents of respective feeders, and if there is a certain feeder satisfying the maximum characteristic frequency current amplitude, and this feeder is not the longest feeder or the characteristic frequency current phase thereof lags behind that of other feeders, determining that the feeder is a faulty feeder. The design of the present invention has good economical efficiency, practicability and implementability.

A method for battery power management based on battery nonlinearity characterization and compensation using a nonlinear resistor-capacitor (RC) equivalent circuit model (ECM) may include: measuring a current, a terminal voltage, and a temperature of a battery; implementing the nonlinear RC ECM comprising fixed, logarithmically spaced time constants and current dependent resistances and capacitances; constraining resistances of the nonlinear RC ECM to be nonnegative and performing a nonlinearity characterization procedure using the nonlinear RC ECM configured to characterize variations of a battery impedance with current amplitudes over a range of frequencies and create ECM parameter variations with current amplitudes by fitting impedance variations by nonlinear RC ECMs; performing online estimation of the nonlinear RC ECM using a battery current and a terminal voltage of the battery over time; and modifying the online estimated nonlinear RC ECM using ECM parameter variations to compensate for nonlinearity of the battery.

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 provides a fault ride-through control method and a fault ride-through control system for a grid-forming converter, which are characterized in that the current of the grid-forming converter under an asymmetric fault is controlled by adopting a negative-sequence current reference generation strategy aiming at an inner ring of a controller, and negative-sequence reactive current is injected into a power grid; adopting a partial sequence current amplitude limiting strategy to control the maximum phase current amplitude of the injected asymmetric current not to exceed an amplitude limiting value; controlling the boundary of an active reference value by adopting an active reference value amplitude limiting strategy for an active synchronization ring; a synchronous damping link is adopted to enhance damping in power angle swing; for a reactive voltage loop, a reactive voltage variable coefficient control strategy is adopted to control the output of the maximum reactive current; and an internal potential locking strategy is adopted to suppress overvoltage. According to the invention, negative-sequence reactive power is provided, and overcurrent of each phase is avoided; the power angle characteristic is improved, and the transient stability is improved; stable transient voltage support is provided in a current output capability range; and after the fault is recovered, the voltage of the converter grid-connected point is smoothly recovered.

The invention discloses a phase jump fault recovery method and system for a network-building type inverter, and the method comprises the steps: giving a-q-axis current component of a current loop reference value of the network-building type inverter as an allowable maximum current value in response to a phase jump fault of a power grid and triggering a current amplitude limiting request of the network-building type inverter, forming an amplitude limiting current loop reference value and limiting the amplitude of the output current of the grid-forming inverter; after the current amplitude limiting is relieved, the active power of the grid-forming type inverter is updated, a current loop reference value of the grid-forming type inverter is updated through the updated active power, and the current loop reference value is the current loop reference value obtained after the current amplitude limiting of the amplitude limiting current loop reference value is relieved; and under the condition that the current loop reference value is smaller than a preset current threshold value, the power grid is switched into a grid construction control state, so that the transient stability of the system is enhanced, the system can return to the balance point autonomously, and the grid construction operation state is recovered.

The invention provides a carrier and an electromagnetic valve control method and system. The control method comprises the steps that a characteristic parameter set of an electromagnetic valve is obtained; characteristic parameters of each dimension in the characteristic parameter set are analyzed and determined according to parameters influencing the response of the electromagnetic valve; determining the flutter current frequency of the characteristic parameter set; determining a flutter current amplitude based on the characteristic parameter set and a first mapping relation; the first mapping relation represents the mapping relation between the characteristic parameter set and the flutter current amplitude; the target current is generated according to the flutter current frequency and the flutter current amplitude, the target current is used for controlling the electromagnetic valve, the accuracy of valve element control of the electromagnetic valve is improved, the hysteresis effect of the electromagnetic valve is eliminated, and then the dynamic response speed and the control precision of the electromagnetic valve are improved.

A low voltage ride through control method for a grid-forming inverter based on dynamic internal potential adjustment comprises the following steps: detecting a voltage per unit value of a grid-connected point in real time, and comparing the voltage per unit value with a threshold value to judge a voltage drop event and trigger low voltage ride through control; dynamically calculating active and reactive power reference values through a reactive compensation equation and an active current limiting equation according to the voltage amplitude and the power reference value before falling during the ride-through period; inputting the active reference value into a virtual rotor motion equation to generate a reference phase, and outputting a phase reference signal in combination with a dual-mode phase compensation controller; superposing the reactive reference value with the reference voltage through a reactive voltage regulating ring to generate a voltage amplitude reference signal; synthesizing an internal potential according to the phase and the amplitude reference signal, and obtaining an inductive current reference value through virtual impedance control and current amplitude limiting; and finally, a driving signal is generated through the current inner loop controller and the modulation module. According to the invention, overcurrent can be effectively inhibited, rapid reactive power support is provided, and synchronous stability and smooth transition in a fault period and a recovery process are ensured.

The invention discloses a stability criterion method considering a current amplitude limiting link for a network construction type energy storage system, and belongs to the field of stability control of a power system. According to the invention, the problem of virtual power angle switching after current saturation of the grid-forming converter is solved. The equivalent acceleration area and the equivalent deceleration area serve as the reflection of the energy increment and the energy decrement in the transient process of the converter, and the transient synchronization stability of the grid-connected system of the grid-forming type energy storage converter can be conveniently judged by comparing the acceleration area and the deceleration area or comparing the fault cut-off angle and the limit cut-off angle; the research result has a certain significance in improving the stability of the network construction type energy storage equipment.

The invention discloses a method for measuring the impedance of a grid-connected inverter, which relates to the technical field of impedance measurement of the grid-connected inverter and is characterized in that impedance types and measurement accuracy needing to be measured are determined, the impedance types comprise output impedance and ground insulation impedance, and according to the measurement method and equipment requirements, a data acquisition module is used for setting parameters for acquiring measurement data, the parameters comprise a frequency range, a current amplitude value and a voltage amplitude value, the data processing and analysis module processes and analyzes measured data, calculates an impedance value, compares a calculation result with an expected value and a previous measured value for verification, and in the measurement process, the control and safety module controls starting, stopping and parameter setting of measurement equipment, so that the measurement accuracy is improved. And the working state of the inverter and the safety condition in the measurement process are monitored in real time, and the measurement process, the measurement result and the analysis are written into a measurement report to be uploaded to a system terminal, so that the accuracy and the reliability of impedance measurement of the grid-connected inverter are improved.

The invention mainly relates to the technical field of direct current circuit breakers, and discloses a photovoltaic special circuit breaker system and method, and the system comprises a signal monitoring module, an abnormity recognition module, a path diagnosis module, a fault derivation module, an isolation control module, a path recovery module, and an action optimization module. According to the system, detailed parameters of path conduction are formed by extracting current amplitudes and direction changes of adjacent nodes, abnormal nodes can be accurately positioned, the conduction path range is marked, and the abnormal node fluctuation range, the amplitude change direction and the input and output deviation in the path are comprehensively calculated in combination with an isolated forest algorithm. According to the method, a specific path and an end point range of abnormal propagation can be quickly analyzed, so that the circuit breaker has quick response, multi-level diagnosis and optimization adjustment capabilities in a complex scene, and the safety, the reliability and the operation efficiency of a direct current system are improved.

The invention discloses a transformer fault intelligent diagnosis method and system, and the method comprises the steps: reading a longitudinal differential protection action switching value from transformer fault recording, according to the fault recording information, calculating rated current of each side of the transformer, longitudinal three-phase differential current amplitude, voltage and current amplitude of each side and zero-sequence voltage and zero-sequence current amplitude of each side; and combining different criteria to intelligently identify fault types such as a non-internal fault, a three-phase symmetric fault, a single-phase earth fault, a two-phase earth fault, a two-phase interphase short circuit and an interturn fault of the transformer, and fault sides and fault phases. According to the invention, the fault type and the fault position of the transformer can be rapidly and automatically positioned, manual fault analysis is assisted or replaced, and an intelligent automatic solution is provided for accident handling of the transformer fault in an engineering field.

The invention provides a low-voltage ride-through control method for a grid-forming type grid-connected converter based on reactive power synchronization, and belongs to the technical field of converter low-voltage ride-through control. When the voltage of a power grid drops, a current amplitude limiting module in the power grid sends a control switching signal to trigger low-voltage ride-through control, and the low-voltage ride-through control is switched to a reactive power synchronization mode; a reactive power synchronous control gain KQs is calculated according to an inner loop gain coefficient Kcp, a current amplitude limiting value, a power grid voltage Vg and a grid side inductance Lgi, a virtual power angle reference value is generated by combining a set reactive power direct current component reference value QN, so that a power angle delta is stabilized in a range close to a normal working point, and a control effect is verified by comparing with a traditional method. According to the method, the system can quickly recover to a normal working state regardless of the duration of the fault and the severity of the fault, meanwhile, the system can effectively work under different power grid fault levels, and the robustness of the system is further enhanced.

The invention relates to the technical field of network construction type converter control, in particular to a network construction type converter fault ride-through method and system based on dynamic virtual resistance control, and the method comprises the steps: adding a control link based on virtual impedance in a network construction type converter control system; detecting the actual value of the power grid voltage, and judging whether the power grid voltage drops or not; detecting the current amplitude output by the grid-forming converter in real time, and judging whether the current amplitude exceeds a set value or not; if one of the two conditions is met, a virtual impedance control link is started: stage-type current limiting control is performed on the virtual resistor, and the size of the virtual resistor provided by the network-forming converter to the power system is adjusted in real time along with the amplitude of the fault current; and when the power grid voltage recovers and the current amplitude is smaller than the set value, the virtual resistor staged current-limiting control exits. According to the invention, the amplitude limiting of the fault current in the fault ride-through of the network-constructed converter can be realized, so that the fault ride-through capability and transient stability of the network-constructed converter are improved.

The invention provides an electric vehicle power battery thermal runaway fault detection method, system and device and a medium, and belongs to the technical field of battery detection. The method comprises the following steps: acquiring an original current time sequence generated by operation of a power battery and preprocessing the original current time sequence to obtain a current time sequence; sampling and analyzing the current time sequence to obtain a plurality of first current amplitude standard deviations; evaluating the plurality of first current amplitude standard deviations according to a standard deviation threshold to obtain a thermal runaway fault preliminary detection result of the power battery; when it is preliminarily detected that the power battery may have a thermal runaway fault, Fourier transform is performed on the current time sequence to obtain a current frequency domain sequence; sampling and analyzing the current frequency domain sequence to obtain a plurality of second current amplitude standard deviations; and evaluating the plurality of second current amplitude standard deviations according to an evaluation standard to obtain a final detection result of the thermal runaway fault of the power battery. Whether the power battery has a thermal runaway fault can be accurately detected.

Techniques to help improve efficiency or effectiveness of treating a disorder such as RLS or PLMD, such as by issuing neural electrostimulations to a particular patient, while varying one or more amplitude parameters (e.g., at least one of electrostimulation current amplitude, electrostimulation voltage amplitude, or electrostimulation pulsewidth duration). A corresponding patient-subjective or patient-objective response can be observed. A characteristic electrostimulation intensity relationship can be generated, for example, based on the determined respective at least one of RLS or PLMD response indication threshold amplitude parameters and the plurality of corresponding neural electrostimulation durations. Once this characteristic electrostimulation intensity relationship has been generated, it can then be used to control issuing subsequent neural electrostimulations to the particular patient according to (1) at least one goal and (2) a variable operating point based upon the generated characteristic electrostimulation intensity relationship.

The invention discloses a distributed photovoltaic power quality monitoring method. The method comprises the following steps: acquiring original waveform data of the Internet of Things in real time through a serial peripheral interface; calculating cyclic wave voltage amplitude, cyclic wave harmonic voltage and / or current amplitude, inter-harmonic voltage and / or current amplitude, harmonic active power, positive sequence, negative sequence and zero sequence components of voltage and / or current and unbalance degree according to the original waveform data; and calculating an instantaneous flicker value through a filter according to the original waveform data, and carrying out transient rise, transient drop and interruption event monitoring according to the original waveform data. According to the invention, the technical problems of how to monitor the electric energy quality quickly in real time and how to calculate the frequency deviation in real time are solved.

The invention provides a new energy grid-connected converter fault ride-through method and system under an asymmetric fault, and the method comprises the steps: calculating the positive sequence voltage amplitude of a power grid and the voltage unbalance degree of the power grid according to the positive and negative sequence parameters of the power grid; judging whether the power grid is in a normal state or a fault state; when the power grid is in the asymmetric fault state, current amplitude limiting is carried out by adopting a calculation formula of a positive and negative sequence current instruction in the asymmetric fault state based on the related parameters of the power grid fault, and the amplitude limiting value of the positive and negative sequence current instruction of the new energy grid-connected converter in the asymmetric fault state is calculated; feedback control is carried out according to the amplitude limiting values of the positive and negative sequence current instructions, and fault ride-through is completed; according to the method, the current is subjected to amplitude limiting in the calculation formula of the positive and negative sequence current instructions, so that the positive and negative sequence active and reactive current control target can be met to the greatest extent on the premise of ensuring that overcurrent of the converter does not occur, and the power grid supporting capacity during the fault period is improved.

The invention relates to the technical field of electronic component testing for investigating or analyzing internal microstructures and physical properties of materials by utilizing an electrical means, and discloses an online testing and analyzing method for physical properties of electronic component materials, which comprises the following steps of: constructing a composite excitation signal formed by linearly superposing a main carrier voltage and a perturbation wave voltage; applying the signal to a to-be-tested electronic component and acquiring response current; and extracting an intermodulation current amplitude at an intermodulation frequency point in the frequency spectrum of which the linear response interval is excluded, calculating a nonlinear response coefficient of the material in combination with the excitation amplitude, and comparing the nonlinear response coefficient with a preset degradation threshold so as to judge whether the nonlinear response coefficient is qualified or not. By extracting intermodulation components which cannot be generated by linear contact resistance, physical isolation of external contact noise in a frequency domain is realized, and the problem that contact resistance fluctuation and material intrinsic aging cannot be distinguished in a traditional linear impedance test is solved.

The invention belongs to the field of single-phase earth fault line selection, and provides a small-current grounding system single-phase earth fault line selection method and system. The method comprises the following steps: acquiring fault current information of a small current grounding system; extracting fault features in the fault current information; the fault characteristics at least comprise a zero-sequence current amplitude, a zero-sequence current phase angle, a fifth harmonic current amplitude, a fifth harmonic current phase angle and a transient zero-sequence current amplitude; the extracted fault features are parallelly and correspondingly input to a first neural network model, and single-phase earth fault line selection initial results corresponding to the fault features are obtained; the number of parallel fault classifiers contained in the first neural network model is the same as the number of fault features; and inputting all the initial line selection results into the second neural network model to obtain a final single-phase earth fault line selection result.

The invention discloses an ISOP type medium-voltage DC converter LLC module fault diagnosis method and device, a medium-voltage DC power supply system and a storage medium. Comprising the following steps: monitoring an input capacitor voltage, an input current, an output voltage and an output current of each LLC module port; according to the output voltage and the output current, judging whether a fault condition of the ISOP type medium-voltage direct-current converter is met or not; under the condition that it is judged that the fault condition is met, the difference between the input capacitor voltage change rate, the input voltage amplitude and the input current amplitude of each LLC module is calculated; according to the input capacitor voltage change rate, the input voltage amplitude and the input current amplitude, the LLC module with the switch tube open-circuit fault or the input capacitor aging fault in all the LLC modules is judged. According to the scheme of the invention, the online detection and positioning of the fault LLC module are completed by using the difference between the electrical quantity amplitudes and the change rates of the LLC modules, and the phenomenon of misdiagnosis caused by large input voltage fluctuation is avoided.

The invention relates to the technical field of motor state monitoring, in particular to a motor state monitoring method and system based on data driving, and the method comprises the following steps: synchronously collecting a motor voltage signal amplitude time domain sample and a motor current signal amplitude time domain sample for a power frequency period in a motor operation state; and calculating an instantaneous phase difference between each corresponding sample point to obtain an instantaneous phase difference original data stream of the motor. The method comprises the following steps: synchronously acquiring voltage and current amplitudes during operation of a motor in real time, and calculating an instantaneous phase difference between the two amplitudes to obtain an electromagnetic state original data stream; further executing high-pass filtering and performing spectral analysis to filter interference signals and low-frequency trend influences, and improving the recognition precision and robustness of instantaneous phase difference jitter features; meanwhile, voltage pulses are actively injected into the winding, echo signals are collected, and rapid capturing and positioning of the abnormal state of the winding are achieved through propagation time delay calculation and impedance characteristic construction.

The invention relates to a fault current analysis method based on first-order Taylor expansion, and the method comprises the following steps: 1, determining a system control strategy which is a network construction type control strategy and comprises a power loop, a virtual impedance link and a voltage and current loop; the power loop comprises an active power control loop and a reactive power control loop; 2, constructing a differential algebraic equation set model capable of representing the dynamic state of the system; 3, according to the characteristic that the integral value does not suddenly change at the moment before and after the fault occurs, the steady state before the fault is utilized to solve and obtain an instant state variable value after the fault, and then an instant dq-axis current value after the fault and an instant current amplitude value after the fault are obtained; 4, performing first-order Taylor expansion on the constructed differential algebraic equation set at the solved post-fault instant state variable value and the dq-axis current value, and converting a nonlinear differential algebraic equation set model into a linear differential algebraic equation set; and 5, analyzing the fault current.

The invention discloses a coordinated control method and device for a deep fault of a wind power sending end and a storage medium, and belongs to the field of safe operation of a power system. The coordination control method comprises the following steps: when a deep fault occurs at a sending end in a wind power flexible direct sending scene, S1, increasing the q-axis current amplitude of a wind power plant, reducing the d-axis current amplitude of the wind power plant, and increasing the amplitude limiting value of the q-axis current of the MMC sending end to a set value so as to meet the low-voltage fault ride-through requirement of the wind power plant; s2, detecting the voltage recovery condition of the grid-connected point of the wind power plant, and judging whether the fault is cleared or not; if yes, executing S3; if not, returning to execute S1; and S3, during the fault recovery period, adopting a suppression strategy to suppress transient overvoltage, and increasing the d-axis current of the wind power plant until the voltage of the sending end of the MMC is recovered to a steady-state value. And in case of a ride-through fault, the transient stability of the wind power plant and the MMC sending end becomes better, and the synchronization stability of the phase-locked loop is improved.

The invention provides a method and a system for evaluating reactive power supporting capability of a network-forming type wind turbine generator, and relates to the technical field of power systems, and the method comprises the steps: obtaining active power outputted by a to-be-tested generator before disturbance; adding disturbance, adjusting the terminal voltage amplitude of the to-be-tested unit, and recovering after setting time; obtaining the steady-state reactive current amplitude variation of the to-be-tested unit after disturbance; and drawing a positive-sequence reactive current variable quantity requirement curve, and judging whether the steady-state reactive current-voltage characteristics of the to-be-tested unit meet requirements or not according to the position relation between the steady-state reactive current amplitude variable quantity of the to-be-tested unit after disturbance and the drawn positive-sequence reactive current variable quantity requirement curve. According to the method, the reactive power supporting capability of the network-forming type wind turbine generator can be accurately evaluated.

The invention relates to the technical field of power distribution network fault early warning, and discloses an early warning system and method for a power distribution network ground fault. The data acquisition module of the system acquires multi-mode monitoring data such as zero-sequence current waveform, grounding wire current amplitude phase, insulator leakage current and environment temperature and humidity of the power distribution network in real time, and comprehensively reflects the operation state of the power distribution network. And the feature fusion module performs spatial-temporal feature compensation on the multi-modal monitoring data to generate a fault feature tensor, so that the insulation degradation evolution period of the topological node of the power distribution network is determined, and the insulation state change is accurately evaluated. And the risk deduction module analyzes a dynamic communication path of the topological structure of the power distribution network, performs fault conduction modeling, determines a ground fault risk situation level in combination with multi-modal monitoring data, and comprehensively considers fault conduction characteristics and operation conditions. The early warning decision module generates a dynamic early warning strategy according to the insulation degradation evolution period and the risk situation level, and the early warning mode is flexibly adjusted.

The invention discloses a self-adaptive charging and discharging coordination control method and system for an energy storage battery, and relates to the technical field of charging and discharging control of the energy storage battery. The method comprises the following steps: correcting a maximum allowable current based on a real-time collected SOC and a preset battery low charge threshold, a battery high charge threshold, a reference coefficient, a first attenuation coefficient and a second attenuation coefficient to obtain an inner loop current amplitude limit; judging whether the current system reaches current saturation or voltage saturation, and marking a corresponding saturation mark; calculating a saturation difference value and a saturation direction angle based on the current value controlled and output by the inner ring and the current value actually output by the inner ring; according to the saturation mark, the saturation difference value and the inner loop current amplitude limit are used for correcting the preset outer layer reference power, the corrected reference power is obtained, the integration gain in the preset integration link is corrected, and the saturation state is relieved; stability and reliability of charging and discharging control of the energy storage system are guaranteed, power control precision is improved, service life of equipment is prolonged, and energy conversion efficiency is improved.

The invention provides a power distribution network fault section rapid calibration method based on a feeder terminal. According to the method, power distribution network line electrical quantity and distributed power supply output information are collected in real time through a feeder terminal and preprocessed, then fault transient signals are processed through complete set empirical mode decomposition of mean value self-adaptive noise, and intrinsic mode components are obtained to judge fault types. Thirdly, fault section preliminary positioning is carried out, and an approximate area is determined according to a positive sequence voltage vector for a symmetric short-circuit fault, a negative sequence voltage vector for an asymmetric short-circuit fault and a zero sequence current amplitude for a single-phase earth fault; then accurate calibration is carried out, a single-phase earth fault is judged through a filter and correlation coefficients, and short circuit and broken line faults are calibrated through a model or an intelligent algorithm in combination with line topology and electrical parameters. And finally, establishing a target function containing a penalty term, converting the target function into a Markov decision process, solving through an approximate dynamic programming algorithm, realizing rapid and accurate calibration of a fault section, and improving the power supply reliability of the power distribution network.

The invention discloses a low-voltage distribution box temperature rise abnormity identification method based on an improved fuzzy clustering algorithm. The method comprises the following steps: S1, generating a temperature-current synchronous acquisition data set according to a time sequence; s2, constructing a load-temperature difference weight matrix in combination with the current current amplitude; s3, obtaining a current membership matrix and a cluster center set; s4, calculating the membership slip amount of each measuring point according to the current membership matrix and the membership matrix at the previous moment, and generating a temperature rise trend state sequence; s5, judging whether the temperature rise trend state sequence has a measuring point which continuously slides from the normal cluster to the risk cluster or not; if yes, corresponding cluster centers in the corresponding cluster center sets are extracted and mapped to the physical coordinates according to the measuring point index table, and positioning information containing the measuring point numbers, the types of the electrical parts and the risk levels is generated. According to the invention, the fault positioning accuracy and the operation and maintenance efficiency are greatly improved.

The invention discloses a transmission line disconnection fault identification method and device based on multi-stage current comparison, and the method comprises the steps: extracting the zero-sequence current data of a fault line and the tripping signal data and reclosing signal data of a protection device from a fault recording file or a protection recording file obtained from the two sides of the fault line, the fault process of the line is divided into a plurality of stages; calculating per unit values of the current fundamental frequency amplitudes of the two sides of the fault line in each stage by taking the maximum value in the current fundamental frequency amplitudes of the stage before the fault as a current amplitude reference value; and judging the disconnection condition of the faulty line based on comparing the per-unit value with the disconnection fault judgment coefficient kdx and the grounding judgment coefficient kjd. According to the invention, the fault process is divided into a plurality of stages, and each time period in which the line may be disconnected or grounded is fully considered; the method can efficiently and accurately judge the line breaking fault of the line and whether the condition of grounding after line breaking exists, and does not cause misjudgment with the grounding fault.