Method and device for suppressing turn-to-turn short-circuit fault current of permanent magnet wind driven generator

Abstract

The invention belongs to the field of permanent magnet generator fault diagnosis and control, and provides a permanent magnet wind generator turn-to-turn short circuit fault current suppression method and device, and the method is generally divided into three steps: damping winding working principle, fault detection and fault current control. According to a signal provided by the fault detection unit, whether stator turn-to-turn short circuit occurs in the generator can be preliminarily judged; and a thermal resistance sensor for measuring temperature is arranged in each stator slot and is used for judging the position of a faulted winding. When the position of the fault winding is detected, the magnitude of the damping winding current above the corresponding groove and the impedance of the damping winding are controlled, and the short-circuit current is suppressed by adjusting the circuit parameters of the damping winding in real time through the control unit, so that the value of the short-circuit current is smaller than or equal to the normal winding current; according to the method, fault current can be effectively inhibited, more serious loss caused by fault deterioration is prevented, and the reliability of the permanent magnet generator is improved.

Description

Technical Field

[0001] The invention belongs to the field of permanent magnet generator fault diagnosis and control, and in particular relates to a method and a device for suppressing inter-turn short-circuit fault current of a permanent magnet wind generator. Background Art

[0002] The stator winding is a key component for energy conversion in offshore permanent magnet wind turbines. The working environment of offshore permanent magnet generators is harsh, and the operating conditions are complex and changeable. The insulation of the windings not only bears a huge electromagnetic load, but also faces a series of severe tests such as overheating, aging and wear. Therefore, the insulation of the winding is very likely to be damaged, thus causing a short circuit fault. Among them, the turn-to-turn short circuit fault occurs more frequently in permanent magnet wind turbine faults. When the fault occurs, the external main insulation of the stator winding remains good, but the insulation layer between adjacent coils of the same-phase winding is damaged, some coils are in contact and short-circuited, and the short-circuit current is very large, which will cause the local temperature to soar, and then aggravate the damage to the adjacent insulation system. When the fault is serious, the motor will burn out, causing huge economic losses.

[0003] It is worth noting that when a permanent magnet generator has a turn-to-turn short-circuit fault, there is a short-circuit current higher than the rated value inside the faulty winding. The faulty winding will generate excessive heat and heat up severely, which will lead to a significant increase in the thermal stress of the faulty winding insulation. The faulty winding insulation may be damaged faster due to high temperature, thereby further aggravating the turn-to-turn short-circuit fault. Therefore, it is necessary to take some measures to reduce the faulty winding current of the generator, prevent the fault from worsening and causing more serious losses, and improve the reliability of the generator. Most of the short-circuit current suppression methods reported have been implemented from the perspective of optimizing the main structure of the generator by adjusting the winding layout, winding shape, slot-pole matching, stator structure and air gap length of the generator. Although the short-circuit winding impedance can be increased and the short-circuit loop back electromotive force can be reduced by adjusting the main structure of the permanent magnet generator, thereby suppressing the short-circuit current under the turn-to-turn short-circuit fault, the high impedance design will inevitably lead to power density loss and reduce the energy conversion efficiency of the generator. In addition, the short-circuit fault current suppression effect of the high-impedance motor is limited, and it is difficult to reduce the short-circuit fault current to within the rated value.

[0004] In view of the shortcomings of the above-mentioned method, the present invention proposes a method and device for suppressing inter-turn short-circuit fault current of a permanent magnet generator based on a damping winding. This method and device not only have low requirements on the accuracy of fault detection technology, but also can effectively suppress the fault current, prevent the fault from worsening and causing more serious losses, and improve the reliability of the permanent magnet generator. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method and device for suppressing inter-turn short-circuit fault current of a permanent magnet wind turbine generator to solve the problems in the prior art. The technical solution adopted by the present invention is: A method for suppressing inter-turn short-circuit fault current of a permanent magnet wind turbine generator comprises: The first step: a damping groove is provided on the yoke of the stator core of the permanent magnet generator for placing the damping winding; Step 2: Number the stator windings separately and place a thermal resistance sensor in each stator winding; Step 3: Measure the electromagnetic torque signal of the permanent magnet generator and perform FFT transformation on the measured electromagnetic torque signal. If a double frequency harmonic component appears in the spectrum of the electromagnetic torque and the amplitude of the DC component of the electromagnetic torque decreases, it is determined that the permanent magnet generator has a stator turn-to-turn short circuit fault. Step 4: Determine the short-circuit winding position by using the thermal resistance sensor inside the stator winding; Step 5: When the temperature of a stator winding rises rapidly, control the AC power switch of the damping winding corresponding to the corresponding short-circuit winding, and control the impedance of the damping winding to dynamically adjust the short-circuit current so that its value is less than or equal to the normal winding phase current.

[0006] Furthermore, the third step includes: The air gap flux density of the permanent magnet generator is obtained by multiplying the air gap magnetomotive force and the air gap permeance. The short-circuit loop current generated by the faulty winding after the turn-to-turn short circuit will generate a pulsating magnetic field with a cosine variation, which can be expressed as: ; in, F d is the amplitude of the pulsating magnetic potential generated by the short-circuit current; According to the product-to-difference formula, equation (1) can be expressed as: ; in, F d+ It is the short-circuit current induced magnetomotive force with the same direction of rotation as the main magnetic field. F d- It is the short-circuit current induced magnetomotive force that rotates in the opposite direction to the main magnetic field; The air gap magnetomotive force before and after the turn-to-turn short circuit is expressed as: ; in, F s is the fundamental magnetomotive force of the generator stator under normal conditions, F PM is the magnetomotive force of the permanent magnet, ω is the electrical angle, θ is the air gap mechanical angle, ψ is the internal angle, F s+ is the fundamental magnetomotive force of the stator rotating in the forward direction after short circuit, F s- It is the fundamental wave magnetomotive force of the stator rotating in the opposite direction after short circuit; Multiplying equation (3) by the air gap permeance yields the air gap flux density before and after the short circuit: ; The air gap magnetic energy is expressed as: ; If the rotor magnetomotive force has an internal power angle difference Δ ψ , an electromagnetic torque will be generated, which can be expressed as: ; Substituting equations (3) and (4) into equations (5) and (6), we can obtain the expression of electromagnetic torque before and after short circuit: ; in, p is the number of generator pole pairs, l is the stator core length, R is the inner diameter of the stator core; After the short circuit, the DC component of the electromagnetic torque decreases and a new double frequency component appears. The changes in these two components serve as the basis for judging the short circuit fault.

[0007] Furthermore, the fifth step includes: obtaining the temperature in each stator slot through a thermistor sensor. If the temperature in the stator slot of the permanent magnet generator rises rapidly, the short-circuit current is suppressed by adjusting the damping winding current and the impedance. When the fault current is less than or equal to the normal winding current, the control ends.

[0008] A device for suppressing inter-turn short-circuit fault current of a permanent magnet wind generator, comprising a damping winding, a permanent magnet generator, a thermal resistance sensor, a torque sensor, a drive motor, a torque acquisition instrument, a monitoring and control system, an RL circuit, an AC power supply, an AC power switch, a stator core, a damping slot and a stator winding; The stator core is provided with damping slots for installing the damping winding; The permanent magnet generator is connected to the drive motor through a coupling, the torque sensor is connected to the rotating shaft of the permanent magnet generator and the rotating shaft of the drive motor, the torque collector is connected to the torque sensor, a thermal resistor sensor is placed in the stator winding of the permanent magnet generator, and the monitoring and control system is connected to the thermal resistor sensor; the RL circuit is connected to the damping winding, and when a turn-to-turn short-circuit signal is received, the RL circuit is connected to the damping winding to control the impedance of the damping winding; The damping winding is connected to an AC power source, and the monitoring and control system is connected to the AC power source and an AC power switch. When an inter-turn short circuit occurs, the AC power source controls the switch of the corresponding damping winding to pass the AC power source to open.

[0009] The present invention has the following beneficial effects: when a short-circuit fault occurs, there is no need to shut down immediately, and the stable operation of the generator can be guaranteed by suppressing the short-circuit current in real time, thereby avoiding economic losses caused by shutdown maintenance and significantly improving the reliability of the wind power generation system; at the same time, in the early stage of the inter-turn short-circuit fault, the short-circuit current in the faulty winding can be quickly suppressed through dynamic reactance adjustment to avoid further expansion of the short-circuit current, thereby effectively protecting the winding and other key components of the permanent magnet wind generator. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a schematic diagram of the magnetic flux distribution of the winding in the fault slot; Figure 2 The magnetic flux distribution of the winding in the fault slot when the damping winding is used: Figure 2 (a) The direction of the damping winding current is opposite to that of the fault winding current. Figure 2 (b) The direction of the fault winding current is the same as that of the damping winding current; Figure 3 It is the stator turn-to-turn short circuit judgment process; Figure 4 It is a flow chart of dynamic adjustment of damping winding of the present invention; Figure 5 This is the overall structure diagram of inter-turn short-circuit current suppression; Figure 6 This is the installation diagram of the thermal resistance sensor and the damping winding; Figure 7 It is a schematic diagram of the damping winding current and impedance control circuit; In the figure: 1-damping winding, 2-permanent magnet generator, 3-thermal resistance sensor, 4-torque sensor, 5-driving motor, 6-torque collector, 7-monitoring and control system, 8-RL circuit, 9-AC power supply, 10-AC power switch, 11-stator core, 12-damping slot, 13-stator winding. DETAILED DESCRIPTION

[0011] The following will be combined with the embodiments of the present invention Figure 1-Figure 7 , the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0012] The technical solution of the present invention generally includes the working principle of the damping winding, fault detection, and fault current control. The details are as follows: Working principle of damping winding: a damping winding 1 is placed in the stator core 11 of the permanent magnet generator 2. The damping winding 1 has a relatively high resistance and inductance value, and the damping winding 1 does not significantly weaken the stator phase current to reduce the power output when the generator is operating normally. Only when a turn-to-turn short circuit fault occurs in the permanent magnet generator 2, the damping winding 1 will work to generate a magnetic field opposite to the short-circuit current to suppress the short-circuit current.

[0013] First, the magnetic flux distribution of the winding in the fault slot is analyzed. When a turn-to-turn short circuit fault occurs, the magnetic flux distribution in the stator fault slot is as follows: Figure 1 As shown. Since the fault winding current consists of two parts, the phase current and the additional circulating current (short-circuit path current), the fault winding flux also consists of two parts: the phase current main flux and the additional circulating flux. The difference is that there is only phase current in the normal winding, so there is only phase current main flux in the normal winding. The direction of the fault winding flux is the same as that of the normal winding flux. When the fault winding current and the normal winding current are both in the clockwise direction, the fault winding flux and the normal winding flux are both in the BA direction, so the synthetic flux in the fault slot is also in the BA direction.

[0014] The method for suppressing the inter-turn short-circuit fault current proposed in the present invention is that after the damping winding 1 is energized, an induced electromotive force will be generated in the fault loop composed of the fault winding and the short-circuit path, and then an induced current will be generated. As long as the direction of the induced current is controlled to be opposite to the fault current, the fault current can be effectively reduced. When the damping winding 1 is used, the magnetic flux distribution of the winding in the fault slot is as follows: Figure 2 As shown. When the fault current and the normal winding current are both clockwise, if the fault current is to be reduced, the induced current in the fault winding should be counterclockwise. From Ampere's law, it can be seen that the direction of the magnetic field of the induced current is in the BA direction. Further analysis shows that from Lenz's law, the effect of the induced current always opposes the cause of the induced current. Therefore, when the magnetic field along the BA direction is weakened or the magnetic field along the AB direction is enhanced, a counterclockwise induced current can be generated in the fault winding. If the magnetic field along the BA direction is to be weakened, the current of the damping winding 1 should be counterclockwise, and the current decreases with time. At this time, the current of the damping winding 1 is opposite to the direction of the fault winding current, as shown Figure 2 Similarly, if the magnetic field is to be enhanced in the AB direction, the damping winding current should be in the clockwise direction, and the current increases with time. At this time, the damping winding current is in the same direction as the fault winding current, as shown in Figure 2 In addition, an induced current will also be generated in the normal winding. Since the number of turns of the normal winding is much larger than that of the damping winding, the damping winding has little effect on the phase current.

[0015] Fault detection: Permanent magnet wind turbines are prone to inter-turn short circuit faults in high-salt and high-humidity offshore environments, which will reduce the reliability of the generator operation and may lead to serious consequences, such as winding burnout. Therefore, it is extremely important to find a suitable fault indication parameter, and the generator electromagnetic torque, which is not easily affected by external interference, can be used as the target parameter for generator inter-turn short circuit fault detection. Next, the changes in electromagnetic torque before and after the short circuit will be specifically analyzed.

[0016] The air gap flux density of the permanent magnet generator can be obtained by multiplying the air gap magnetomotive force and the air gap permeance. The inter-turn short circuit mainly affects the air gap magnetomotive force and has no effect on the air gap permeance. The short-circuit loop current generated by the faulty winding after the inter-turn short circuit will generate a pulsating magnetic field with a cosine change, which can be expressed as: ; in, F d It is the amplitude of the pulsating magnetic potential generated by the short-circuit current.

[0017] According to the product-to-difference formula, equation (1) can be expressed as: ; in, F d+ It is the short-circuit current induced magnetomotive force with the same direction of rotation as the main magnetic field. F d- It is the short-circuit current induced magnetomotive force that rotates in the opposite direction to the main magnetic field.

[0018] Therefore, the air gap magnetomotive force before and after the turn-to-turn short circuit can be expressed as: ; in, F s is the fundamental magnetomotive force of the generator stator under normal conditions, F PM is the magnetomotive force of the permanent magnet, ω is the electrical angle, θ is the air gap mechanical angle, ψ is the internal angle, F s1+ is the fundamental magnetomotive force of the stator rotating in the forward direction after short circuit, F s1- It is the fundamental magnetomotive force of the stator rotating in the opposite direction after short circuit.

[0019] Multiplying equation (3) by the air gap permeance, we can get the air gap flux density before and after short circuit: ; In the process of electromechanical energy conversion of the generator, the air gap magnetic field stores most of the energy. The air gap magnetic energy can be expressed as: ; According to the virtual displacement principle, if the rotor magnetomotive force has an internal power angle difference Δ ψ , an electromagnetic torque will be generated, which can be expressed as: ; Substituting equations (3) and (4) into equations (5) and (6), we can obtain the expression of electromagnetic torque before and after short circuit: ; in, p is the number of generator pole pairs, l is the stator core length, R 0 is the inner diameter of the stator core.

[0020] It can be seen from equation (7) that a new double frequency component appears after a short circuit, and the DC component of the electromagnetic torque will decrease. The changes in these two components can be used as a basis for judging short circuit faults. According to the above principle, the basic process for judging turn-to-turn short circuit is as follows: Figure 3 As shown: First, the electromagnetic torque signal of the generator is measured and the electromagnetic torque signal is transformed by FFT. If the DC component of the electromagnetic torque spectrum decreases and a double frequency signal appears, it is judged that a turn-to-turn short circuit fault has occurred in the generator. If the DC component of the electromagnetic torque spectrum does not change and there is no double frequency component, it is judged that the generator is operating normally without a turn-to-turn short circuit fault.

[0021] like Figure 5-Figure 6 , a method for suppressing inter-turn short-circuit fault current of a permanent magnet wind turbine generator, the specific steps are as follows: Step 1: A damping groove 12 is provided on the yoke of the stator core 11 of the permanent magnet generator for placing the damping winding 1, which are d 1 d 2 d 3 d 4 d 5 d 6 d 7 d 8 d 9 d 10 d 11 d 12 d 13 d 14 d 15 d 16 d 17 d 18 d 19 d 20 d 21 d 22 d 23 d 24 d 25 d 26 d27 , d 28 , d 29 , d 30 , d 31 , d 32 , d 33 , d 34 , d 35 , d 36 , d 37 , d 38 , d 39 , d 40 , d 41 , d 42 , d 43 , d 44 , d 45 .

[0022] Step 2: Number the stator windings 13 as w 1 , w 2 , w 3 , w 4 , w 5 , w 6 , w 7 , w 8 , w 9 , w 10 , w 11 , w 12 , w 13 , w 14 , w 15 , w 16 , w 17 , w 18 , w 19 , w 20 , w 21 , w 22 , w 23 , w 24 , w 25 , w 26 , w 27 , w 28 , w 29 , w 30 , w 31 , w 32 , w 33 , w 34 , w 35 , w 36 , w 37 , w 38 , w 39 , w 40 , w 41 , w 42 , w 43 , w 44 , w 45, a thermal resistor sensor 3 is placed in each stator winding 13, respectively t 1 ,t 2 ,t 3 ,t 4 ,t 5 ,t 6 ,t 7 ,t 8 ,t 9 ,t 10 ,t 11 ,t 12 ,t 13 ,t 14 ,t 15 ,t 16 ,t 17 ,t 18 ,t 19 ,t 20 ,t 21 ,t 22 ,t 23 ,t 24 ,t 25 ,t 26 ,t 27 ,t 28 ,t 29 ,t 30 ,t 31 ,t 32 ,t 33 ,t 34 ,t 35 ,t 36 ,t 37 ,t 38 ,t 39 ,t 40 ,t 41 ,t 42 ,t 43 ,t 44 ,t 45 Used to measure winding temperature.

[0023] Step 3: Measure the electromagnetic torque signal of the permanent magnet generator 2, perform FFT transformation on the measured electromagnetic torque signal, if the double frequency harmonic component appears in the spectrum of the electromagnetic torque, and the amplitude of the DC component of the electromagnetic torque decreases, it is judged that the permanent magnet generator 2 has a stator turn-to-turn short circuit fault. The specific process is as follows: Figure 3 shown.

[0024] Step 4: Since the huge short-circuit current after the turn-to-turn short circuit will generate huge heat at the short-circuit winding, causing the temperature of the faulty winding to rise sharply, the specific short-circuit winding position can be determined by the thermal resistor sensor 3 installed inside the stator winding 13 in the second step.

[0025] Step 5: When it is found in the monitoring and control system 7 that the temperature of a stator winding 13 rises rapidly, the AC power switch 10 that controls the flow through the damping winding 1 corresponding to the corresponding short-circuit winding is turned on, and the impedance of the damping winding 1 is controlled to dynamically adjust the short-circuit current to make its value less than or equal to the normal winding phase current, such as Figure 7 shown.

[0026] like Figure 4 First, the temperature in each stator slot of the permanent magnet generator 2 is obtained through the thermal resistor sensor 3. If the temperature in the stator slot rises rapidly in a short period of time, and combined with the previous fault detection, it is determined that a turn-to-turn short circuit fault has occurred in the permanent magnet generator 2, the location of the faulty winding can be determined. The temperature signal generated by the faulty winding will be collected and used to control the damping winding 1 corresponding to the stator fault slot to work. The short-circuit current is suppressed by adjusting the current and impedance of the damping winding 1. When the fault current is less than or equal to the normal winding current, the control ends. If the temperature in the stator slot does not rise rapidly in a short period of time, it is determined that the generator is operating normally.

[0027] The present invention also relates to a device for suppressing inter-turn short-circuit fault current of a permanent magnet wind generator, comprising a damping winding 1, a permanent magnet generator 2, a thermal resistor sensor 3, a torque sensor 4, a drive motor 5, a torque collector 6, a monitoring and control system 7, an RL circuit 8, an AC power supply 9, an AC power switch 10, a stator core 11, a damping slot 12 and a stator winding 13; The permanent magnet generator 2 is connected to the drive motor 5 through a coupling, wherein the two ends of the torque sensor 4 are connected to the rotating shaft of the permanent magnet generator 2 and the rotating shaft of the drive motor 5 respectively, and the torque collector 6 is used to measure the electromagnetic torque characteristic signal for judging the occurrence of inter-turn short circuit fault in the permanent magnet generator. A thermal resistor sensor 3 for measuring the winding temperature is also placed in the stator winding 13 of the permanent magnet generator 2, and the monitoring and control system 7 is used to detect the temperature signal transmitted by the thermal resistor sensor 3 and judge the specific inter-turn short circuit position. The RL circuit 8 is connected to the damping winding 1, and when the inter-turn short circuit signal is received, the RL circuit 8 will be connected to the damping winding 1 to control the damping winding impedance.

[0028] In addition, the damping winding 1 is connected to the AC power supply 9, and the monitoring and control system 7 also controls an AC power supply 9 and an AC power switch 10. When an inter-turn short circuit occurs, the AC power supply 9 works to control the corresponding damping winding 1 to enter the switch 10 of the AC power supply 9 to open. The specific working process is as follows: a damping groove 12 is opened in advance on the stator core 11 of the permanent magnet generator to install the damping winding 1. The permanent magnet generator 2 is driven to rotate by the driving motor 5, and the torque sensor 4 is used to detect the electromagnetic torque signal and collect it through the torque collector 6. If the DC component of the electromagnetic torque decreases and a double frequency component appears, it is determined that the permanent magnet generator 2 has an inter-turn short circuit fault. After the short circuit occurs, the temperature of the corresponding winding will rise rapidly in a short time. The specific position of the inter-turn short circuit fault winding can be accurately located by the thermal resistor sensor 3. After the short-circuited winding position can be checked in the monitoring and control system 7, the RL circuit 8 is controlled to connect to the damping winding 1 to adjust the impedance of the damping winding circuit. In addition, the monitoring and control system 7 will also accurately control the size of the flow into the damping winding through the AC power supply 9 and the switch 10.

[0029] The embodiments described above are only descriptions of the preferred modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations, modifications, and substitutions made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for suppressing inter-turn short-circuit fault current of a permanent magnet wind turbine generator, characterized in that: include: The first step is to open a damping groove (12) on the yoke of the stator core (11) of the permanent magnet generator for accommodating the damping winding (1); Step 2: Number the stator windings (13) respectively, and place a thermal resistance sensor (3) in each stator winding (13); Step 3: Measure the electromagnetic torque signal of the permanent magnet generator (2), perform FFT transformation on the measured electromagnetic torque signal, and if a double frequency harmonic component appears in the spectrum of the electromagnetic torque and the amplitude of the DC component of the electromagnetic torque decreases, it is determined that a stator turn-to-turn short circuit fault occurs in the permanent magnet generator (2); Step 4: Determine the short-circuit winding position by using a thermal resistance sensor (3) inside the stator winding (13); Step 5: When the temperature of a stator winding (13) rises rapidly, the AC power switch (10) of the damping winding (1) corresponding to the corresponding short-circuit winding is controlled, and the impedance of the damping winding (1) is controlled to dynamically adjust the short-circuit current so that its value is less than or equal to the normal winding phase current.

2. The method for suppressing the inter-turn short-circuit fault current of a permanent magnet wind turbine generator according to claim 1 is characterized in that the third step include: The air gap flux density of the permanent magnet generator (2) is obtained by multiplying the air gap magnetomotive force and the air gap permeance. The short-circuit loop current generated by the faulty winding after the turn-to-turn short circuit will generate a pulsating magnetic field with a cosine variation, which is expressed as: ； in, F d is the amplitude of the pulsating magnetic potential generated by the short-circuit current; According to the product-to-difference formula, equation (1) can be expressed as: ； in, F d+ It is the short-circuit current induced magnetomotive force with the same direction of rotation as the main magnetic field. F d- It is the short-circuit current induced magnetomotive force that rotates in the opposite direction to the main magnetic field; The air gap magnetomotive force before and after the turn-to-turn short circuit is expressed as: ； in, F s is the fundamental magnetomotive force of the generator stator under normal conditions, F PM is the magnetomotive force of the permanent magnet, ω is the electrical angle, θ is the air gap mechanical angle, ψ is the internal angle, F s1+ is the fundamental magnetomotive force of the stator rotating in the forward direction after short circuit, F s1- It is the fundamental wave magnetomotive force of the stator rotating in the opposite direction after short circuit; Multiplying equation (3) by the air gap permeance yields the air gap flux density before and after the short circuit: ； The air gap magnetic energy is expressed as: ； If the rotor magnetomotive force has an internal power angle difference Δ ψ , an electromagnetic torque will be generated, which can be expressed as: ； Substituting equations (3) and (4) into equations (5) and (6), we can obtain the expression of electromagnetic torque before and after short circuit: ； in, p is the number of generator pole pairs, l is the stator core length, R 0 is the inner diameter of the stator core; After the short circuit, the DC component of the electromagnetic torque decreases and a new double frequency component appears. The changes in these two components serve as the basis for judging the short circuit fault.

3. The method for suppressing inter-turn short-circuit fault current of a permanent magnet wind turbine generator according to claim 1, characterized in that: The fifth step includes: obtaining the temperature in each stator slot through a thermal resistor sensor (3); if the temperature in the stator slot of the permanent magnet generator (2) rises rapidly, the short-circuit current is suppressed by adjusting the current and impedance of the damping winding (1); when the fault current is less than or equal to the normal winding current, the control ends.

4. A device for suppressing inter-turn short-circuit fault current of a permanent magnet wind generator, adopting a method for suppressing inter-turn short-circuit fault current of a permanent magnet wind generator as claimed in any one of claims 1 to 3, comprising a damping winding (1), a permanent magnet generator (2), a thermal resistor sensor (3), a torque sensor (4), a drive motor (5), a torque acquisition instrument (6), a monitoring and control system (7), an RL circuit (8), an AC power supply (9), an AC power switch (10), a stator core (11), a damping slot (12) and a stator winding (13); The stator core (11) is provided with a damping slot (12) for mounting a damping winding (1); The permanent magnet generator (2) is connected to the drive motor (5) through a coupling, the torque sensor (4) is connected to the rotating shaft of the permanent magnet generator (2) and the rotating shaft of the drive motor (5), the torque collector (6) is connected to the torque sensor (4), a thermal resistor sensor (3) is placed in the stator winding (13) of the permanent magnet generator (2), and the monitoring and control system (7) is connected to the thermal resistor sensor (3); the RL circuit (8) is connected to the damping winding (1), and when a turn-to-turn short-circuit signal is received, the RL circuit (8) is connected to the damping winding (1) to control the impedance of the damping winding; The damping winding (1) is connected to an AC power source (9), and the monitoring and control system (7) is connected to the AC power source (9) and an AC power switch (10). When an inter-turn short circuit occurs, the AC power source (9) controls the corresponding damping winding (1) to pass through the AC power switch (10) and turn on.

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