199 results about "Line current" patented technology

The invention discloses an electricity meter terminal temperature anomaly identification method, system and device and a storage medium, and relates to the technical field of intelligent electricity meter monitoring and anomaly detection.The method comprises the steps that currents of a live line loop and a zero line loop of an intelligent electricity meter are sampled, and the deviation rate of the live line current relative to the zero line current is calculated; estimating the temperature of the terminal of the electric energy meter based on the deviation rate and by using the resistance characteristic metering error change trend of the manganese-copper shunt; and when the terminal temperature estimated value of the electric energy meter exceeds a preset threshold value, determining that the temperature of the live wire terminal is abnormal, and recording an alarm event. The method realizes real-time acquisition of current difference characteristics, provides a reliable data basis for subsequent terminal temperature estimation, realizes a method of indirectly reflecting terminal temperature rise through electrical characteristics, ensures that alarm can be triggered and a complete tracing chain can be formed when temperature abnormity occurs, and improves the accuracy of terminal temperature estimation. Therefore, the controllability of the operation safety of the electric energy meter and the completeness of post analysis are improved.

The invention discloses a low-voltage distribution area topology identification method, system and device and a storage medium, and the method comprises the following steps: deploying a synchronous measurement unit in a low-voltage distribution area, and obtaining the outgoing line current phasor and voltage phasor data with a synchronous time scale of a whole network; constructing an incoming line and outgoing line current phasor set, and performing adaptive descending sorting according to amplitudes; determining that the nodes corresponding to the incoming line current phasors and the found nodes corresponding to the one or more outgoing line current phasors are in a father-son relationship, and iterating the process until all sets are empty, thereby completing the identification of the topological relationship of the power distribution side; and according to the equipment number contained in the obtained voltage phasor data, determining a meter box connected with the user electricity meters, and then clustering the user electricity meters connected to the same meter box according to the voltage phase angle to obtain the connection phase sequence of each user electricity meter. The problem of key information missing is solved from a data source, and accurate and efficient identification of topology is realized by fusing physical constraints.

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 an electric power system transient stability rapid response control method and system, and relates to the technical field of electric power systems, and the method comprises the steps: collecting a transient harmonic current signal generated by a power grid fault in real time through a harmonic detection unit connected to a DC bus of an energy storage converter, and calculating the phase offset of the transient harmonic current signal; generating a power control instruction through a pre-configured hardware mapping circuit based on the phase offset; acquiring a current differential signal by using a power grid line current sensor, and identifying a path of transient energy flowing to a key unit based on a power grid topological structure; for the path, dynamically forming a virtual high-impedance wall on the target line; and on a consumption path predefined according to the power grid topological structure, controlling the energy storage converter to operate in a current source mode and configuring a reverse power characteristic so as to absorb the energy flow turned by the virtual high-impedance wall.

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 main and distribution collaborative optimization scheduling method and system based on a static safety boundary of a power distribution network, and relates to the field of power system optimization scheduling, and the method comprises the steps: converting a voltage / current safety boundary of the power distribution network into the static safety boundary of the power distribution network through hyperplane linearization; establishing global safety margin indexes of the node voltage and the line current of the power distribution network, and introducing a safety margin weight coefficient to balance the priorities of the node voltage margin and the line current margin; determining margin income based on the global safety margin index and the safety margin weight coefficient, and establishing a dynamic weight adjustment mechanism to update the safety margin weight coefficient; constructing a target function based on the power generation cost of the main power grid, the new energy power abandoning penalty of the power distribution network and the margin income; and obtaining power grid data, and solving the main-distribution collaborative optimization model by using a quadratic programming method and the power grid data to obtain a main-distribution collaborative optimization scheduling scheme. According to the invention, bidirectional power interaction and collaborative optimization of the main power grid and the power distribution network are realized.

The invention discloses an intelligent opening and closing method and system for a reclosing circuit breaker based on an electromagnet, and relates to the field of intelligent control, and the method comprises the steps: monitoring a line current in real time, comparing the line current with a preset threshold value, and carrying out the opening after the overcurrent abnormality is detected. Entering a first time delay stage after opening, comprehensively evaluating the states of the circuit breaker and the circuit, and constructing a dynamic weight index system to calculate an evaluation score; if the score exceeds a threshold value, closing is carried out after time delay is finished, otherwise, an alarm is triggered. And entering a second delay stage after switching on, continuously monitoring the electric parameters and establishing an anomaly judgment mechanism, forming a closed-loop protection process of monitoring, switching off, evaluating, switching on and re-monitoring, and realizing intelligent linkage of overcurrent protection and state self-adaption. The method has the advantages that through real-time line electric parameter monitoring, multi-dimensional state evaluation and an intelligent decision-making mechanism, precise opening and closing of the circuit breaker are achieved, the power supply reliability is improved, the power failure time is shortened, and the misoperation risk is reduced.

The invention discloses an impedance-adjustable series hybrid cascade static synchronous compensator and a control method thereof. The method comprises the following steps: acquiring grid-connected point voltage and load current information, and performing positive and negative sequence component analysis on the grid-connected point voltage and load current information; calculating a compensation line current component with the same size and opposite phase as the positive and negative sequence components of the load current so as to compensate the reactive power and the negative sequence current of the grid-connected point load; zero-sequence injection current used for in-phase active power balance is calculated, and reference operation current of each cascade branch is obtained; calculating the output reactive power of each phase based on the cascade branch voltage of each phase and the reference operation current, calculating the corresponding trigger angle of each phase thyristor under the condition that the adjustable impedance bears all phase voltages and generates all reactive power, and generating a pulse control signal to realize the control of the adjustable impedance; and each phase cascade converter adopts quasi-proportional resonance control to track the reference operation current, and generates a corresponding PWM signal to respectively control each phase cascade converter.

The invention discloses a rapid spare power automatic switching device and method suitable for high-proportion distributed power supply access, and the device comprises a local sampling module which is used for collecting a local side bus voltage Ulocal and an incoming line current Ilocal; the switching value acquisition module is used for acquiring the TWJ state of the switch at the side; the communication module is used for communicating with an opposite-side remote transmission device through an HDLC protocol and acquiring opposite-side switch position information Kremote and an opposite-side voltage state Uremote; programmable logic is arranged in the logic processing module, and the logic processing module is used for executing comprehensive judgment logic; and the control output module is used for executing opening and closing operation of the switch according to the instruction of the logic processing module. Compared with a traditional spare power automatic switching technology, the method effectively solves the problems of operation refusal and maloperation caused by access of the high-proportion distributed power supply, and remarkably improves the power supply reliability and the new energy consumption capability.

The invention relates to the technical field of electrical safety, and particularly discloses an arc fault protection method based on a circuit breaker intelligent algorithm, which comprises the following steps: S1, collecting a line current signal in real time, eliminating harmonic interference of a frequency converter from an original signal through an anti-aliasing filter, and converting the original signal into a digital signal; s2, processing the current signal by adopting a three-stage cascade wavelet analysis module, and outputting a dynamic peak-to-average ratio to S4; s3, detecting current disturbance based on a double-slide-rail window, outputting a disturbance positioning mark and a time-frequency feature to S4, judging a disturbance event, and positioning a starting point; s4, receiving the dynamic peak-to-average ratio of the S2 and the disturbance positioning mark and the time-frequency characteristics of the S3, performing path processing according to a characteristic analysis result, and adopting a direct interruption method and an electromagnetic radiation-current frequency domain cross validation method; s5, constructing an electric arc energy accumulation prediction model; according to the invention, the problems of weak arc leak detection, electromagnetic interference maloperation and delay are solved.

The invention discloses a medium-voltage voltage regulating circuit, system and method, and belongs to the technical field of medium-voltage power distribution. The medium-voltage voltage regulating circuit comprises a tapped voltage regulating transformer Tr1, a voltage compensation unit, a current compensation unit and a direct-current supporting unit, the self-coupling winding of the Tr1 and the series transformer of the voltage compensation unit are connected in series to a medium-voltage main circuit, the parallel winding of the current compensation unit and the self-coupling winding of the Tr1 share a magnetic core and take the self-coupling winding of the Tr1 as a primary side and a secondary side, and the direct current sides of the power module of the voltage compensation unit and the power module of the current compensation unit are both connected to the direct current supporting unit. Wide-range voltage coarse adjustment is achieved through the Tr1, stepless voltage fine adjustment is achieved through the voltage compensation unit, meanwhile, the topological structure is simplified through the common magnetic core coupling design of the self-coupling winding and the parallel winding of the Tr1, the equipment size, the magnetic loss and the manufacturing cost are reduced, and the stability and reliability of a medium-voltage power distribution system are remarkably improved.

The invention relates to a method for monitoring a multi-line device cell (12) for a technical device (1), the device cell (12) having a plurality of sub-cells (21) electrically connected in parallel to one another, comprising the following steps: detecting (S3) a line current through each of the sub-cells (21), determining (S4) a balancing current from the line currents, a balancing current flows through each of two of the sub-cells (21), and if at least one of the balancing currents exceeds a predefined balancing current threshold, a fault or an abnormality is signaled (S5, S6).

The application discloses a kind of conductor operation risk assessment method, system and its terminal equipment, belong to conductor state assessment technical field, this method is: based on real-time operating tension and conductor structure parameter acquisition interlayer comprehensive contact thermal resistance set;Based on real-time line current, conductor structure parameter and preset skin effect coefficient calculation unit length heat generation rate, based on unit length heat generation rate and interlayer comprehensive contact thermal resistance set constructs radial temperature distribution thermal circuit model;Conductor surface layer temperature and ambient temperature are input in radial temperature distribution thermal circuit model to obtain real-time temperature;Based on real-time temperature and temperature-mechanical property degradation model obtains tensile strength, to based on tensile strength and conductor structure parameter calculation limit bearing capacity;Based on real-time operating tension to obtain actual share load and calculate safety margin, to based on safety margin and preset safety threshold value output the risk assessment result of to-be-measured conductor, realize to the precise dynamic evaluation of each layer failure risk in conductor internal.

The application discloses a power stealing point detection method, device, system, server and medium. The method is applied to a power distribution network system, the system comprises at least one main line, at least one first-level branch line and at least one second-level branch line; the method comprises the following steps: acquiring current signals of each main line, each first-level branch line and each second-level branch line; acquiring incoming line current signals on each main line, each first-level branch line and each second-level branch line; judging whether the incoming line current signals of each main line, each first-level branch line and each second-level branch line are same as the sum of the current signals of each main line; if not same, judging whether any main line current signal is same as the sum of the current signals of each corresponding first-level branch line and the sum of the incoming line current signals on the main line; if same, judging whether any first-level branch line current signal is same as the sum of the current signals of each corresponding second-level branch line and the sum of the incoming line current signals on the first-level branch line; if not same, judging that a power stealing point is on the first-level branch line.

The invention discloses a current differential protection adaptability analysis method for an alternating current line of a new energy network flexible direct output system, and belongs to the technical field of power system relay protection. Establishing a system fault equivalent model based on a low-voltage ride-through control strategy of power electronic equipment at two sides of the outgoing line; according to different asymmetric fault types and a fault point boundary condition equation, deriving mathematical models of positive-sequence, negative-sequence and zero-sequence currents on the two sides of a fault phase line; calculating a differential current and a braking current, and establishing a function relationship between the differential current and the braking current and the VSG internal potential reference value, the transition resistance and the current sequence component ratio; and the action sensitivity of protection under different working conditions is judged by comparing the current differential protection ratio braking coefficient setting value with the current differential protection ratio braking coefficient setting value. The association rule of the current differential protection refusal risk and the low-pass control parameters under the high transition resistance fault is disclosed, a basis is provided for protection setting and control strategy optimization of a network construction flexible direct output system, and the problems that a protection adaptability analysis method is weak and the influence rule of the control parameters is not clear yet are solved.

The invention discloses a graphical fault distance measurement method and system, relates to the field of traction substation tripping fault mark distance measurement in the railway industry, and can read a fault report of a fault distance measurement device and constant value parameter configuration of the fault distance measurement device off line, and calculate and analyze a fault type, whether line current is balanced or not and a fault distance according to the data and parameters. And a result is graphically displayed, so that the distance measurement error range can be narrowed by modifying and verifying the constant value parameters, and the corrected constant value parameters are exported and stored, thereby achieving the purposes of facilitating fault analysis, improving the working efficiency and shortening the maintenance time. Maintenance personnel are helped to quickly find out fault points, timely process faults and recover normal operation of lines, and the method is very important for safe, reliable and efficient transportation of a railway system.

The invention discloses a line current differential protection false information detection method based on a delay observer, and is applied to the technical field of line current differential protection. Comprising the following steps: establishing a distribution parameter model of the power transmission line, and discretizing the distribution parameter model to obtain a discrete model of the power transmission line; constructing a delay observer based on the discrete model of the power transmission line, solving a parameter matrix of the delay observer, and estimating a negative sequence voltage predicted value at the current moment; reading a negative sequence voltage measured value at the current moment, and calculating an error between the negative sequence voltage predicted value and the negative sequence voltage measured value; and if the error is greater than a preset error threshold value, judging that the line current differential protection system is attacked by false information injection. According to the method, false information injection can be effectively identified by monitoring the negative sequence voltage prediction error, and the reliability of current differential protection and the safe operation level of a power grid are improved.

A voltage-controlled bridge is coupled to the line voltage and the transformer primary harmonic voltage, while a current-controlled bridge is coupled to the line current and the transformer secondary harmonic voltage. A synchronous average harmonic current compensator synchronously integrates the error between the measured bridge current and the command current every half-switch cycle and samples the compensator output to control the line current and linearize the harmonic coupling between the isolation bridges. A synchronous pulse-width modulation process tracks the commanded line voltage. One or more of the primary and secondary harmonic command circuits regulate the harmonic coupling voltages of the voltage-controlled and current-controlled bridges, respectively. The line voltage, line current, and primary and secondary harmonic commands provide generalized line and isolation voltage bus regulation freedom within a single stage.

The application belongs to the technical field of integrated circuits, and discloses a circuit structure for one-step solution of linear equations based on a memristor array, wherein the linear equations are Ax=b, and in the circuit, a first memristor array matrix operation core realizes mapping of the matrix A, takes a negative value of a first operation voltage vector as a bit line voltage, performs a matrix multiplication operation, reads a word line current as a first operation current vector after the operation, a bias mapping module maps b into a bias current vector, a current superposition module superimposes the first operation current vector and the bias current vector to generate a superimposed current vector, and converts the superimposed current vector into a second operation voltage vector through a transimpedance amplifier module, a second memristor array matrix operation core realizes mapping of the matrix A, takes the second operation voltage vector as a bit line voltage, performs a matrix multiplication operation, reads a word line current, and performs an integral operation on the word line current through an integrator module to obtain an updated first operation voltage vector. T The above hardware circuit can realize solution of the linear equations.

This invention relates to a dual-loop converter for a linear-rotating switched reluctance generator and its control method. The drain of the positive switching transistor of each phase of the rotating generator unit is connected to a first positive circuit, and the source of the negative switching transistor of each phase of the rotating generator unit is connected to a first negative circuit. One end of a load resistor is connected to a first load circuit and a second load circuit connected in parallel, and the other end of the load resistor is connected to a third load circuit and a fourth load circuit connected in parallel. The cathode of the diode of each phase of the rotating generator unit is connected to the first load circuit, and the positive terminal of the winding of each phase of the rotating generator unit is directly connected to the third load circuit. The cathode of the diode of each phase of the DC generator unit is connected to the second load circuit, and the positive terminal of each phase of the DC generator unit is directly connected to the fourth load circuit. This invention solves the technical problems of existing converters using a large number of components and having high line current pressure.

The invention discloses a low-voltage power distribution network overload rapid cut-off device which comprises a device shell, a wire inlet wiring terminal hole is formed in the left end of the front side of the device shell, a wire outlet wiring terminal hole is formed in the right end of the front side of the device shell, and a state indicator light hole and a manual reset key hole are correspondingly formed in the front side of a panel of the device shell. The main control circuit board is embedded in the middle area of the interior of the device shell, and the overload detection chip is attached to the center area of the upper surface of the main control circuit board. Power is supplied by the power module, the overload detection chip collects line current in real time, a threshold value is preset in combination with a built-in potentiometer, and an electromagnetic triggering mechanism is rapidly triggered during overload; the double-breakpoint circuit breaker is pushed to cut off the circuit, delay protection and mistaken touch prevention are achieved, a state indicator lamp feeds back the state, a manual reset key is convenient to recover, rapid overload response and thorough cut-off are achieved, safety protection and easy maintenance are achieved, and stability of a low-voltage power distribution network is guaranteed.

Embodiments of the present disclosure relate to a current detection device for an electrical grid. A detection device for a DC electrical grid comprises: - a first detection module configured to detect a line current flowing along an electrical line and to provide a first detection signal indicative of the line current; - a second detection module configured to detect the line current along the electrical line and to provide a second detection signal indicative of a rate of change of the magnitude of the line current over time; - a plurality of signal processing modules for processing the first detection signal and the second detection signal and for providing a detection signal indicative of a behavior of the line current.

The application provides a power connection assembly and a power transmission and distribution line power connection device with the same. The power connection assembly comprises a power connection hook with an opening direction downward, an operating member movably arranged on the power connection hook, and a pressing assembly comprising a driven connecting rod and a driving connecting rod arranged at an acute angle, the upper end of the driven connecting rod is hinged to the power connection hook, the lower end of the driven connecting rod and the lower end of the driving connecting rod are hinged, the upper end of the driving connecting rod is hinged to the operating member, and the operating member drives the lower end of the driven connecting rod to swing out through the driving connecting rod. A locking member is arranged between the operating member and the power connection hook, and the locking member has a locking state of limiting the movement of the operating member relative to the power connection hook and an unlocking state of allowing the movement of the operating member relative to the power connection hook. The technical scheme provided by the application can solve the problem that the line clamp arranged on the non-inspection section line is prone to loosening and falling in the related art.

The invention discloses an early warning method, device and system for an electricity stealing behavior of a single-phase ammeter, a medium and a product, and belongs to the field of power systems, and the method comprises the steps: obtaining the first live line current, the first zero line current and the electricity utilization condition of a plurality of single-phase ammeters in a to-be-detected region; determining a plurality of first electricity larceny risk users based on each first live wire current and each first zero wire current, determining a plurality of second electricity larceny risk users based on each first electricity larceny risk user, and calculating current characteristics of each first electricity larceny risk user and each second electricity larceny risk user, determining a plurality of third electricity larceny risk users based on the current characteristics, and inputting the electricity consumption conditions corresponding to the third electricity larceny risk users into a preset electricity larceny evaluation model to obtain a plurality of electricity larceny scores; and determining a target electricity stealing user based on each electricity stealing score, and performing early warning on electricity stealing of a single-phase ammeter of the target electricity stealing user. According to the invention, the early warning efficiency and accuracy of the electricity stealing behavior of the single-phase ammeter can be improved.

The application relates to a method and device for monitoring an inter-pole short-circuit fault of a direct-current transmission line, a controller, a storage medium and a computer program product. The method comprises obtaining a local direct-current line current and a remote direct-current line current of a rectifier station, and a remote direct-current line current and a local direct-current line current of an inverter station; if an absolute value of a difference between the local direct-current line current of the rectifier station and the local direct-current line current of the inverter station is greater than a first preset threshold value within a preset time, and an absolute value of a difference between the local direct-current line current of the rectifier station and the remote direct-current line current of the rectifier station is less than a second preset threshold value, it is determined that the direct-current transmission line has an inter-pole short-circuit fault; the first preset threshold value and the second preset threshold value are different. The method can accurately identify the inter-pole short-circuit fault in the direct-current transmission line.

The invention provides a spare power automatic switching control method, device and equipment for multiple power supply incoming lines, and relates to the technical field of power system relay protection. The method comprises the following steps: acquiring a power supply loop operation mode of a double-petal power distribution network; in a segmented spare power automatic switching mode, a charging condition is determined according to the on-off state of a segmented circuit breaker and an emergency power supply circuit breaker, and a discharging condition is determined according to the abnormal condition of a relay at the post-closing position of an incoming power supply circuit breaker of each segment of bus when one segment of bus loses voltage. Determining a discharge condition according to a post-acceleration state of the section circuit breaker when the two sections of buses are in voltage loss; in the incoming line spare power automatic switching mode, determining a charging condition according to the on-off state of the section circuit breaker and the emergency power supply circuit breaker, and determining a discharging condition according to the on-off state of the section circuit breaker or the emergency power supply circuit breaker, the working incoming line current and the voltage of the bus section where the working incoming line is located; and controlling the switching of the spare power automatic switching power supply according to the charging condition and the discharging condition. According to the invention, rapid and reliable switching of more than five paths of power supplies can be realized.

The invention relates to the technical field of power systems, in particular to a new energy multi-station broadband oscillation systematized tracing method and device and electronic equipment, and the method comprises the steps: generating a topological graph of a new energy multi-station through obtaining the topological structure and electrical quantity data of the new energy multi-station, carrying out the synchronous processing and numbering of fault recording data, and obtaining a new energy multi-station broadband oscillation source; according to the method, broadband phasors of voltage of each power flow node and line current are identified, related parameters of broadband power flow are determined by combining modal power flow calculation, and finally a panorama of display equipment, power flow nodes, lines and broadband power flow parameters thereof is generated, so that accurate source tracing and positioning of broadband oscillation of new energy multi-station stations are realized, the efficiency and accuracy of oscillation source tracing are improved, and the method is suitable for popularization and application. The limitation that it is difficult to systematically analyze the oscillation problem of the whole or multiple new energy stations in the prior art is solved, and powerful support is provided for stable control and safety protection of a power system.

This invention provides a method for obtaining breakdown voltage, a computer-readable storage medium, and a terminal. The method includes: providing a flash memory device, the flash memory device including word lines, control gates located on both sides of the word lines, and a dielectric layer between the two; applying a first voltage to the control gates, and applying a second voltage to the word lines within a preset voltage range with a preset step size; measuring and obtaining the word line current and control gate current under each of the second voltages, wherein the word line current is the current flowing into the word line, and the control gate current is the current flowing out of the control gate; and obtaining the breakdown voltage of the dielectric layer based on the word line current and the control gate current; wherein the first voltage is less than 0V, and the second voltage is greater than or equal to 0V. This invention solves the problem of inaccurate breakdown voltage of the dielectric layer between the word lines and the control gates obtained by existing methods.

The invention provides a load balancing and voltage compensation method and device based on an electromagnetic element, and the method comprises the steps: controlling a zero-sequence current filter connected in parallel with a low-voltage power distribution network line, blocking the zero-sequence fundamental current and zero-sequence higher harmonic current of a load from flowing into a zero line, transferring the preset part of the maximum phase current in the three-phase load to the other two phases, reducing the maximum phase current and the line resistance voltage drop; controlling the three-phase multi-stage split-phase switched capacitor bank, compensating the reactive power of the line and reducing the negative sequence component of the current of the line, so that the current of the three-phase line reaches a preset balance degree value; reducing the overvoltage of the other two phases, increasing the voltage corresponding to the maximum phase current, and preventing the bidirectional out-of-limit of the voltage of the three-phase unbalanced load; and controlling a remote communication module to remotely monitor the running states of the zero-sequence current filter and the three-phase multi-stage split-phase switched capacitor bank. The stability and the electric energy quality of the power distribution network can be effectively improved.

The invention belongs to the technical field of electrified railway traction power supply, and particularly relates to a traction network multi-terminal longitudinal differential protection system and method in a bilateral through AT power supply mode. The system is provided with multi-terminal longitudinal differential protection elements according to uplink and downlink feeder lines, multi-terminal branches formed by traction substations, AT stations and partition stations are covered, and each branch is provided with a current transformer. The protection element comprises a power frequency variable quantity current differential element, a T line / F line current differential element and a low-voltage differential current starting element which are respectively adaptive to fault transient state and steady state characteristics, and rapid fault identification and accurate fault removal are realized through cooperative action. The method combines a current threshold criterion, a voltage criterion and an opposite-side permission signal, ensures the action quickness, selectivity, sensitivity and reliability, realizes quick removal of power supplies at two ends of a fault, reduces the fault isolation range, and ensures safe and stable operation of a traction network.