68 results about "Three phase short circuit" patented technology

The invention relates to the technical field of power distribution network protection, and discloses a power distribution network fault scene constant value verification method based on reinforcement learning, and the method comprises the steps: constructing a hierarchical multi-agent verification system; a hierarchical multi-agent verification system is constructed, a high-level agent performs fault situation awareness and decomposes a global constant value verification target, sub-tasks are allocated to a low-level agent for execution, and task allocation and execution are realized through collaborative optimization; after a large number of distributed photovoltaics are connected into the power distribution network, the complexity and uncertainty of a power distribution network fault scene are enhanced, fault types comprise two-phase short circuit, two-phase grounding short circuit and three-phase short circuit, the protection behavior difference under different fault positions is obvious, the fault characteristics are changed, the increasing assisting and drawing-out effects are generated, and the reliability of the power distribution network fault scene is improved. Therefore, over-current protection range changes, protection mismatch, override trip and maloperation are caused, and power failure range is expanded. For a complex fault scene, a layered multi-agent architecture is adopted, and efficient task allocation and execution are realized through high-level coordination and bottom-level negotiation.

The utility model discloses a stator three-phase short circuit device, and belongs to the field of stator three-phase short circuit mechanisms. Three sets of conductive clamps and driving clamping pieces are arranged in the device, and an elastic element is arranged between a fixed conductive clamping arm and a movable clamping arm which are hinged to each other in each conductive clamp. Therefore, the driving clamping piece can drive the conductive clamp to the stator phase end after clamping the fixed conductive clamping arm in the conductive clamp, and enables the cambered surface of the protruding part in the movable clamping arm to be in contact with the stator phase end and to continuously move towards the direction close to the stator phase end. And embedding and clamping of the stator phase end A and the conductive clamp are realized under the action of automatic guiding of the lug boss and elastic deformation of the elastic element. The conducting strip does not need to be manually connected to the stator phase end in related technologies, so that the efficiency of stator three-phase short circuit is improved, and the production efficiency of a stator mass production line integrated with the device is improved.

The application discloses an inverter power three-phase short-circuit fault current analytic method considering a phase-locked loop and a current inner loop transient process, and belongs to the technical field of photovoltaic grid-connected system fault analysis. The application studies the transient process of SRF-PLL under different damping ratios, analyzes the influence of the transient process of SRF-PLL on the coordinate transformation of PCC point voltage and current, finally considers the influence of the transient process of SRF-PLL and the current inner loop on the fault current, introduces a correction coefficient, and decomposes the phase current component expressions of the inverter port fault current into the phase current components of the inverter port current under the first influence condition and the phase current components of the inverter port current under the second influence condition. Through the application, the transient characteristics of the IIDG can be more accurately analyzed, the short-circuit characteristic analysis of the IIDG is perfected, and a reference basis is provided for the fault characteristic analysis of the IIDG.

The invention provides a flexible direct-current transmission short-circuit current control strategy multi-objective optimization solving method, which specifically comprises the following steps of: 1, constructing a receiving end fault two-port model, and solving parallel fault transition impedance in a receiving end power grid fault model; step 2, in combination with parallel fault transition impedance, deriving a minimum reactive current reference value constraint required by AC voltage support in a fault period and an active current constraint allowed by DC side energy balance and DC voltage upper limit; and step 3, obtaining the short-circuit current safety domain under the three-phase short-circuit fault by combining the minimum reactive current required for reducing the voltage drop when the short-circuit fault occurs, the active current which can be provided by the receiving-end converter station MMC and the amplitude constraint condition of the short-circuit current output by the receiving-end converter station MMC. According to the invention, adaptive analysis and optimization are carried out on an existing short-circuit current control strategy, and it is ensured that the optimized control strategy not only can reduce unbalanced power accumulation, but also can be used for supporting alternating-current power grid voltage through reserved capacity.

This invention proposes a multi-objective optimization solution method for short-circuit current control strategy in flexible DC transmission, specifically including: Step 1, constructing a two-port model of the receiving-end fault and solving for the parallel fault transition impedance in the receiving-end grid fault model; Step 2, combining the parallel fault transition impedance, deriving the minimum reactive current reference value constraint required to support AC voltage during the fault, and the active current constraint allowed by the DC side energy balance and DC voltage upper limit; Step 3, combining the minimum reactive current required to reduce voltage drop during a short-circuit fault, the active current that the receiving-end converter station MMC can provide, and the short-circuit current amplitude constraint condition output by the receiving-end converter station MMC, obtaining the short-circuit current safety domain under three-phase short-circuit faults. This invention adaptively analyzes and optimizes existing short-circuit current control strategies, ensuring that the optimized control strategy can both reduce unbalanced power accumulation and support AC grid voltage through reserved capacity.

The invention discloses a self-adaptive current quick-break protection method considering a distributed photovoltaic access position, belongs to the field of circuit protection, and solves the problems that a traditional protection method is poor in selectivity and adaptability in a multi-power-supply scene, and the technical scheme comprises the steps: S1, building a three-phase short-circuit fault mathematical model containing a distributed photovoltaic DPV based on a power distribution network topological structure, and building a three-phase short-circuit fault mathematical model; fault occurrence positions are divided into three types of fault scenes according to the DPV access points; s2, for the three types of fault scenes, analyzing the distribution rule of three-phase short-circuit current, and constructing and normalizing a position influence factor Kpos based on the influence of DPV access on the short-circuit current; and S3, based on the position influence factor Kpos, designing a protection criterion containing a position correction item through a setting principle of avoiding the maximum short-circuit current at the tail end of the line in current quick-break protection, and dynamically adjusting an action current setting value of the protection device according to the protection criterion. According to the invention, the protection reliability of the photovoltaic power distribution network is improved.

The invention discloses a power grid data processing method and device for offshore wind power, terminal equipment and a storage medium, and belongs to the field of offshore wind power, and the method comprises the steps: obtaining a topological structure, a thermal power and wind power output curve, line transmission capacity limitation, a target line and a target node of a receiving-end power grid; calculating the static bearing margin of the AC line; performing cascading failure simulation based on the target line to obtain line transmission capacity after the failure, and calculating a cascading failure toughness margin based on the line transmission capacity after the failure; calculating a three-phase short-circuit current for the target node, and calculating a short-circuit capacity adaptation degree based on the three-phase short-circuit current; and carrying out weighted calculation on the static bearing margin, the cascading failure toughness margin and the short-circuit capacity adaptation degree of the alternating-current line to obtain an adaptability evaluation value, and determining the running state of the receiving-end power grid, so that the problem of low safety of an offshore wind power and conventional power generation combined power transmission system in the prior art can be solved.

The invention provides a photovoltaic accessible capacity evaluation method and device considering network construction type energy storage, and relates to the technical field of power system analysis and new energy grid connection. The method comprises the following steps: constructing a power grid model, and constructing a system impedance matrix based on a network topology structure of the power grid model; a Thevenin equivalent model of the network construction type energy storage device is established, after the Thevenin equivalent model is connected to a power grid node, the system impedance matrix is corrected, a corrected equivalent system impedance matrix is obtained, and the power grid node comprises at least one photovoltaic load access node; when a three-phase short-circuit fault occurs in a target node, the short-circuit ratio and the photovoltaic permeability of the target node are calculated based on the corrected equivalent system impedance matrix, and the target node is any node in the power grid nodes; and determining the increased maximum accessible capacity of the target node according to the short-circuit ratio and the photovoltaic permeability of the target node. The transmission efficiency and reliability of the power grid can be improved.

A motor control device of the present application controls a motor using a detected value of a rotation angle of the motor, based on a measurement result of a magnetic pole position of a magnetic pole position sensor, the motor being driven by a three-phase alternating current and being provided with the magnetic pole position sensor that measures the magnetic pole position of a rotor, in which the motor control device sets any one of the three-phase alternating current when the motor is in a three-phase short circuit as an object phase, compares a current peak time rotation angle that indicates the detected value of the rotation angle when a current value of the object phase is a peak value with a reference rotation angle that indicates the rotation angle when a prescribed current waveform of the object phase is a peak value, and corrects the detected value of the rotation angle based on a comparison result.

This document provides systems and methods for protecting a motor magnet during a three-phase short circuit. A system includes power electronics configured to energize a three-phase electric motor using a plurality of switches, and control switching logic configured to transition the three-phase electric motor into a three-phase short-circuit state using the plurality of switches, and to switch between the three-phase short-circuit state and a three-phase open-circuit state based on a transient current of the three-phase electric motor using the plurality of switches. In some embodiments, the transition from the three-phase short-circuit state to the three-phase open-circuit state occurs in response to the transient current exceeding a threshold value.In some embodiments, the transition to a three-phase short-circuit state occurs in response to at least one of the multiple switches being damaged.

Systems and methods for protecting a motor magnet during a three-phase short condition are provided herein. A system includes power electronics configured to provide current to a three-phase electric motor using a plurality of switches, and control circuitry configured to transition the three-phase electric motor to a three-phase short condition using the plurality of switches, and alternate between the three-phase short condition and a three-phase open condition using the plurality of switches based on a transient current of the three-phase electric motor. In some embodiments, transitioning from the three-phase short condition to the three-phase open condition is in response to the transient current exceeding a threshold. In some embodiments, the transition to a three-phase short condition is in response to at least one of the plurality of switches being damaged.

The invention relates to a large-scale wind power plant sending-out line phase selection method based on transient current waveform characteristics, and belongs to the technical field of power system relay protection. Firstly, transient current of a wind power plant side is collected, and whether a fault is a grounding fault is judged according to the magnitude of zero-mode current; if the fault is a ground fault, absolute values of integral value ratios of transient current fault components of all phases and 1 difference values are calculated, judgment is carried out according to a ratio corresponding to the minimum value delta kmin in the absolute values, if the ratio is smaller than the other two ratios, the fault phase is one phase except the two corresponding phases in the ratios, and if the ratio is larger than the other two values, the fault phase is one phase except the two corresponding phases in the ratios. The fault phase is the corresponding two phases in the ratio; if the fault is a two-phase short-circuit fault or a three-phase short-circuit fault, the ratio of the integral value corresponding to the delta kmin is judged, if the ratio is larger than the other two ratios, the fault is the two-phase short-circuit fault, and otherwise, the fault is the three-phase short-circuit fault. According to the method, the required time window is short, and the problem that fault phase selection is inaccurate when a traditional phase selection method is used for recognizing far-end high resistance is solved.

This invention discloses a method and apparatus for three-phase short-circuit transient modeling of a permanent magnet synchronous motor. The method includes: acquiring the parameter values ​​of the motor body, the initial values ​​of the synchronous motor during a short circuit, and the constraints; determining the dq-axis current value based on the motor body parameters, the initial values ​​during the short circuit, and the constraints; and establishing a three-phase short-circuit transient model based on the dq-axis current value. This invention establishes motor equations and electromagnetic torque equations based on the motor body parameters, and derives an analytical transient model of active short circuit by determining the initial conditions during a short circuit. This allows for the acquisition of the dq-axis current and torque at any given time, providing a precise data foundation for realizing active short circuits. Furthermore, the analytical model helps the controller set reasonable compensation and achieve precise adjustment.

The invention relates to a liquid three-phase power frequency double-loop electromagnetic induction and short circuit heating device and a heating method. The heating device is provided with an iron core, and a three-phase primary winding is wound on a core column of the iron core; and the metal shell is arranged along the three-phase closed magnetic loop to form a double-loop shell structure which surrounds the iron core and the three-phase primary winding and is provided with ten secondary side short-circuit metal rings. During operation, short-circuit large current is induced and generated in the metal rings with the short-circuited secondary sides; each secondary side is conducted through the same metal shell to generate phase-to-phase and three-phase short-circuit heavy current; the short-circuit current directions of the inner and outer secondary sides of each phase are the same, and the magnetic leakage directions of the adjacent secondary sides are opposite to form a strong and stable three-phase power frequency alternating N-S magnetic field, so that the leakage magnetism is greatly reduced, and the temperature rise of the protective shell is greatly reduced; a medium flows through the heating device, and is magnetized by a strong alternating magnetic field without scaling while being heated; the surface load parameter is greatly reduced, and the single-machine design power is effectively expanded.

The invention provides an auxiliary handcart of a high-voltage switch cabinet, which comprises a handcart body, three moving contacts and three test terminals, and is characterized in that the three moving contacts are mounted at the front end of the handcart body in an insulating manner, and the three moving contacts are used for being in contact with the three static contacts when the handcart body is pushed into the high-voltage switch cabinet; the rear end of the vehicle body is provided with three test terminals in an insulated manner. Pressing wheels are arranged at the bottom of the trolley body and used for opening a lifting curtain for shielding a static contact when the trolley body is pushed into the high-voltage switch cabinet. According to the implementation mode, when insulation is measured, the three moving contacts are connected with the three test terminals through the insulated wires, and after the vehicle body is pushed into the high-voltage switch cabinet, the insulation is measured through the test terminals; during grounding, the three test terminals are detached, the three moving contacts and the grounding device are connected through a three-phase short-circuit grounding wire, and grounding is completed after the vehicle body is pushed into the high-voltage switch cabinet. During electricity testing, the three moving contacts and the three testing terminals are detached, and after the vehicle body is pushed into the high-voltage switch cabinet, electricity testing is completed.

The application discloses a new energy multi-station short-circuit ratio calculation method and system, and a storage medium. The method comprises the following steps: performing network topology analysis on a power grid model I containing an external network model to obtain a total topology node set; forming a node admittance matrix according to the device resistance, the electric reactance parameter and the topology node set of the power grid model I, processing the node admittance matrix to obtain a factor table of the node admittance matrix; calculating self-impedance and mutual impedance of nodes corresponding to new energy stations in a node impedance matrix according to the factor table; obtaining short-circuit currents of each node when three-phase short-circuit faults occur, and calculating short-circuit capacities of each node; obtaining new energy multi-station short-circuit ratios of each node according to the short-circuit capacities, the self-impedance and the mutual impedance; and obtaining new energy multi-station short-circuit ratios according to the short-circuit ratios of each node. The application considers the influence of the external network model and the characteristics of a new energy voltage-controlled power supply on the calculation of new energy multi-station short-circuit ratios, and improves the accuracy of the calculation results.

This invention proposes a method for enhancing the stability of power hardware-in-the-loop systems based on DDPG-RP. First, an equivalent circuit model of the system containing grid fault disturbances is established, its dynamic interaction characteristics are analyzed, and the impedance matching conditions for stable operation are determined. Based on this, a phase-compensated and enhanced repetitive-voltage feedforward composite controller is designed. An upper-level intelligent controller is constructed by combining this with a deep deterministic policy gradient algorithm. These two controllers are deployed in the bottom and upper-level control units, respectively, forming a hierarchical collaborative control architecture for grid fault simulation. A test platform is built based on this architecture. After offline training and online deployment of the deep reinforcement learning controller, a three-phase short-circuit fault condition is simulated using a high-power grid-connected interface device to verify its dynamic response and stability. This invention, relying on hierarchical collaboration and intelligent optimization, effectively solves the problem of traditional control systems struggling to balance stability and performance under complex faults, significantly improving system adaptability and robustness.

The present invention relates to a method and system for calculating AC three-phase short-circuit current taking into account flexible direct current (HVDC) transmission. The method comprises: determining the system's node impedance matrix based on the power system's operating mode, as well as the transfer impedance of each power source node to a short-circuit point, the mutual impedance between the flexible direct current (DC) grid connection point and the short-circuit point, and the self-impedance of the short-circuit point; calculating a first short-circuit current at the short-circuit point based on the transfer impedance of each power source node to the short-circuit point; calculating a second short-circuit current provided by a flexible direct current (DC) equivalent current source injected solely into the flexible direct current (DC) grid connection point based on the mutual impedance between the flexible direct current (DC) grid connection point and the short-circuit point and the self-impedance of the short-circuit point; obtaining a maximum short-circuit current provided by the flexible direct current when the first short-circuit current and the second short-circuit current are in phase, and obtaining the AC three-phase short-circuit current of the flexible direct current by vectorially superimposing the first short-circuit current and the maximum short-circuit current. The present invention solves the problem of large deviation in the calculation of the AC three-phase short-circuit current provided by the flexible direct current (HVDC) and can be applied in the field of flexible direct current transmission.

The application discloses a kind of multi-loop high-voltage cable fault calculation method, device, electronic equipment and medium.The multi-loop high-voltage cable fault calculation method includes: when the asymmetric ground short circuit of high-voltage cable metal sheath occurs, asymmetric ground short circuit is converted into target symmetric three-phase short circuit by symmetric component method, and the asymmetric ground short circuit includes single-phase ground short circuit and two-phase ground short circuit;Based on the principle of multi-loop high-voltage cable metal sheath circulating current calculation, the target symmetric three-phase short circuit is calculated, the insulation state of high-voltage cable is determined, to calculate the corresponding multi-loop high-voltage cable fault according to the insulation state.This embodiment studies the insulation state of high-voltage cable line, anticipates high-voltage cable insulation state and takes corresponding measures, which is beneficial to the safety and reliability of high-voltage cable transmission line.

Embodiments of the present application provide a kind of rotary variable zero calibration method, device, electronic equipment and storage medium, wherein, method includes: drag motor rotor rotation and control its rotating speed;Control motor stator winding by three-phase alternating current inverter ASC enters three-phase short circuit, when the rotating speed of the motor rotor is greater than rotating speed threshold and the fluctuation state value of the rotating speed is less than fluctuation threshold, the three-phase current value of three-phase alternating current motor is acquired;According to the three-phase current value, the rotary variable zero is obtained;The rotary variable zero is written into read-only memory. Implement the above embodiment, can reduce error, so that the precision of the obtained rotary variable zero is higher.

The present invention proposes a method and system for allocating the capacity of new energy stations to the grid considering transient overvoltage, which belongs to the technical field of calculation of grid capacity, including: simplifying the grid-connected hybrid station to obtain an equivalent model; calculating the initial value of the grid-connected ratio of each station based on the obtained equivalent model; calculating the stability condition of the phase-locked loop; when configuring the grid-connected converter according to the calculated initial value of the grid-connected ratio for any station, judging whether the phase-locked loop can remain stable after encountering a three-phase short circuit fault based on the stability condition of the phase-locked loop, and calculating the transient overvoltage of the station if it is unstable; when the transient overvoltage is lower than the safety threshold, maintaining the initial value of the grid-connected ratio; when the requirements are not met, deriving the grid-connected capacity ratio expression that meets the transient overvoltage constraint, and correcting the grid-connected ratio of the station to obtain the grid-connected capacity ratio and the grid-connected capacity ratio in any station.

The invention relates to a concept for discharging a DC-link capacitor on an electrical converter by means of the electric converter. For this purpose, the switching elements of all the half-bridges in the electric converter are used to discharge the DC-link capacitor. To this end, firstly all upper or all lower semiconductor switching elements of the electric converter are closed, and subsequently the complementary semiconductor switching elements are periodically actuated with predetermined pulses. In this way, energy is withdrawn from the DC-link capacitor with each pulse.

A method of mitigating electrical faults includes detecting an electrical fault at a first inverter of an electrical propulsion system having the first inverter and a second inverter; activating a three-phase short at a first three-phase electrical circuitry of the first inverter after detection of the electrical fault at the first inverter; and thereafter generating a torque that counters windmilling of the electrical propulsion system by performing at least one of: activating a three-phase short at a second three-phase electrical circuitry of the second inverter; or applying a stoppage voltage via the second inverter.

Provided in the embodiments of the present application are a rotor and an electric motor. The rotor comprises a rotor core and permanent magnets. The rotor core is provided with a plurality of permanent magnet slot groups in the circumferential direction of the rotor core. Each permanent magnet slot group comprises at least two permanent magnet slots arranged in a V-shape with an opening facing outward. The two permanent magnet slots are symmetrical about a first axis of the rotor. One end of each permanent magnet slot is close to the first axis, and the other end thereof is close to a side wall of the rotor core. The permanent magnets are disposed in the permanent magnet slots. Each permanent magnet comprises a main body portion and permanent magnet end portions arranged at two ends of the main body portion in the direction of width thereof, the thickness of the permanent magnet end portions being greater than the thickness of the main body portion. The direction of width of the permanent magnets is perpendicular to the axial direction of the rotor. In the rotor provided in the embodiments of the present application, the thickness of the permanent magnet end portions of the permanent magnets is greater than the thickness of the main body portions in the middle, thereby improving the demagnetization resistance of the permanent magnets at the permanent magnet end portions, reducing the magnetic reluctance of the permanent magnets, increasing the d-axis inductance, reducing a three-phase short-circuit current and improving the continuous operating capability of the electric motor under fault conditions such as a three-phase short circuit.

The invention provides an active power distribution network symmetric fault differential protection method considering T-connection unmeasurable branches, and the method is characterized in that the method comprises the steps: collecting the line head end current IMx and the line tail end current INx of a target line of a power distribution network, and calculating the power distribution network symmetric fault differential protection under the minimum operation mode of a power distribution network system; and performing symmetric fault differential protection on the power distribution network according to a preset differential protection strategy on a short-circuit current value occurring when three-phase short circuit occurs at the tail end of the line based on the line head-end current IMx, the line tail-end current INx and the short-circuit current value. According to the method, the relation between the current at the head end and the tail end of the line and the minimum short-circuit current when the three-phase short circuit occurs at the tail end of the current-level line is analyzed when the symmetrical faults occur in the upstream and the downstream inside and outside the power distribution network line, the three-phase short-circuit identification criterion based on the amplitude ratio characteristic is provided, and the adaptability of the power distribution network to complex fault scenes is improved.

The utility model relates to the technical field of underground mining tools, and discloses a coal mine underground electrical switch three-phase short-circuit grounding device which comprises a connector, the bottom end of the connector is provided with internal threads matched with an underground switch bolt, the top end of the connector is in bolt connection with a connecting body, a connecting cavity is arranged in the connecting body, a movable connecting rod is arranged in the connecting cavity, and the connecting rod is connected with the connector. The head of the connecting rod is matched with a lower hexagonal counter bore in the bottom of the connecting cavity, the upper portion of the connecting cavity is in threaded connection with a wire clamping block, and the bottom end of the wire clamping block is provided with an upper hexagonal counter bore matched with the head of the connecting rod. A wiring nose is sleeved on the screw of the connecting rod above the wire clamping block, two wiring block retaining covers are mounted above the wiring nose, and the tail of the screw of the connecting rod is mounted at the end of the insulating rod and is fixed through a pin penetrating bolt.

This invention discloses a HIL (High-Intensity Logic) testing method, apparatus, and system for testing the controller of a T-type three-level circuit in an electric vehicle. The HIL testing method includes: simulating the operating states of the T-type three-level circuit based on the controller's output signal and a circuit simulation model of the T-type three-level circuit; wherein the operating states of the T-type three-level circuit include normal operation, three-phase short circuit, and transistor off state; determining the three-phase terminal voltage values ​​in the circuit simulation model based on the operating states of the T-type three-level circuit; determining the three-phase current values ​​in the motor simulation model based on the three-phase terminal voltage values; and feeding back the three-phase currents from the motor simulation model to the controller based on a digital-to-analog converter. The technical solution of this invention enables simulation testing of the controller of the T-type three-level circuit in an electric vehicle under different operating states, improving the comprehensiveness and reliability of HIL testing.

The invention relates to the technical field of motor structures, and particularly discloses a double-shaft excitation phase modifier structure optimization method, which comprises the steps of S1, determining magnetomotive force according to k-order harmonic magnetomotive force of a double-layer short-distance coil of a double-shaft excitation phase modifier; s2, merging the magnetomotive forces under different working conditions to obtain a synthetic magnetomotive force; s3, determining the rotor pitch according to the excitation mode of the motor of the double-shaft excitation phase modifier; the excitation mode comprises direct current excitation and alternating current excitation; s4, determining the conductivity of the slot wedge by taking simultaneous minimization of excitation current during three-phase short circuit and variable-speed operation as an optimization target; and S5, determining the structure of the double-shaft excitation phase modifier according to the synthetic magnetomotive force, the rotor pitch and the slot wedge conductivity. Inertia support can be provided for the system, and frequency fluctuation can be suppressed.

The application discloses a method for obtaining three-phase short-circuit current of a doubly-fed fan considering GSC outgoing current of a grid-side converter, and when three-phase short-circuit occurs in a power grid, power fluctuation exists between RSC and GSC under the condition of RSC control; the DC bus voltage fluctuation between RSC and GSC is solved from the power fluctuation of the DC side; the reference value of the grid-side converter current can be obtained according to the DC bus voltage fluctuation; the outgoing current of the grid-side converter can be obtained according to the d and q axis current reference values. The stator short-circuit current in the stationary coordinate system considering RSC control is added to the outgoing current of the GSC, so that the three-phase short-circuit current of the doubly-fed fan considering the outgoing current of the GSC is obtained. Through the application, the transient characteristics of the DFIG can be more accurately analyzed, the short-circuit characteristic analysis of the DFIG is improved, and a basis and reference are provided for the fault characteristic analysis of the DFIG.

A fault phase selection method based on a high-frequency break variable comprises the following steps: after a protection element starting criterion is satisfied, extracting three-phase fault component voltage data 2.5 ms before and after a protection installation position starting moment, calculating break variable voltage of each phase at the protection installation position, and then obtaining a phase selection coefficient of each phase and zero-sequence and positive-sequence break variable voltage; grounding judgment, three-phase short circuit judgment and two-phase short circuit judgment are sequentially carried out, and fault phase selection is achieved. The method can quickly and reliably act, only needs to extract data 2.5 ms after a fault to carry out fault identification, and is high in protection speed and sensitivity.