A synchronous generator insulation fault detection device and method thereof

Abstract

The application discloses a kind of synchronous generator insulation fault detection device and method thereof, synchronous generator includes winding, winding is stator winding or rotor winding;Insulation fault detection device includes: one or several of DC voltage drop detection unit, voltage impulse detection unit or open transformer detection unit;Therefore, by the above detection device and detection method, when synchronous generator fails, the fault position can be positioned faster, to help workers repair in time, reduce power outage time, reduce loss.

Description

Technical Field

[0001] This invention relates to the field of power equipment testing technology, and in particular to a synchronous generator insulation fault detection device and method. Background Technology

[0002] Large synchronous generators are crucial components of power systems. Their stator and rotor insulation performance gradually deteriorates under the long-term effects of high voltage, high current, high temperature, and vibration during operation, and in severe cases, may even break down. When the stator or rotor insulation breaks down, it short-circuits the stator bars or rotor windings to ground, causing unplanned equipment outages and disrupting normal power supply to users.

[0003] However, the current fault detection method can only detect which branch is faulty, but cannot accurately pinpoint which conductor on that branch is faulty. Thus, when a large synchronous generator experiences an insulation breakdown fault, the lack of a fast, accurate, and convenient insulation fault location device will prevent maintenance personnel from quickly locating the fault and assessing the insulation condition. This hinders support for planning maintenance schedules, developing maintenance plans, and calculating spare parts, ultimately preventing maintenance units from quickly restoring equipment operation, increasing power outage time, and causing significant losses. Summary of the Invention

[0004] This invention provides a synchronous generator insulation fault detection device and method, which can quickly, accurately and conveniently locate insulation faults in synchronous generators, reduce power outage time and reduce losses.

[0005] To achieve the above objectives, one embodiment of the present invention provides an insulation fault detection device for a synchronous generator, wherein the synchronous generator includes windings, the windings being stator windings or rotor windings; the insulation fault detection device includes:

[0006] One or more of the following: DC voltage drop detection unit, voltage surge detection unit, or open transformer detection unit;

[0007] The DC voltage drop detection unit is used to provide a constant DC current to the output side and neutral point side of any branch of any phase in the winding. When the current flows through the branch, a third voltage is generated at both ends. The winding insulation fault is detected based on the first voltage between the output side and the ground side of the branch, the second voltage between the neutral point side and the ground side of the branch, and the third voltage.

[0008] The voltage surge detection unit is used to provide a third DC current to the output side of any branch of any phase in the winding, and to detect the winding insulation fault based on the first current peak value on the output side of the branch and the second current peak value on the neutral point side, and / or the discharge phenomenon that occurs in the branch.

[0009] The open-circuit transformer detection unit is used to provide a third AC current to the output side of any branch of any phase in the stator winding, and to detect the stator winding insulation fault based on the induced current of the secondary winding of the open-circuit transformer in the open-circuit transformer detection unit; wherein, the core of the open-circuit transformer is located in the slot of the stator core and is coupled with the stator core to form a current transformer.

[0010] Optionally, the DC voltage drop detection unit includes:

[0011] The first voltage acquisition unit is located between the output side and the ground side of any branch of any phase in the winding, and is used to acquire the first voltage.

[0012] The second voltage acquisition unit is located between the neutral point side and the ground side of any branch of any phase in the winding, and is used to acquire the second voltage.

[0013] The third voltage acquisition unit is located at both ends of the output side and the neutral point side of any branch of any phase in the winding, and is used to acquire the third voltage.

[0014] A DC current source is electrically connected to the output side and the neutral point side of any branch of any phase in the winding.

[0015] A first controller is connected to the first voltage collector, the second voltage collector, the third voltage collector, and the DC current source, respectively, and is used to determine the winding insulation fault when the sum of the first voltage and the second voltage is the third voltage, and the absolute values ​​of the first voltage and the second voltage are both greater than 0.

[0016] Optionally, the first controller is further configured to calculate the ratio between the absolute value of the first voltage and the sum of the absolute values ​​of the first voltage and the second voltage, and to obtain the location of the faulty bar in conjunction with the total number of bars in the branch.

[0017] Optionally, the DC voltage drop detection unit further includes an analog-to-digital converter and a display. The input terminal of the analog-to-digital converter is connected to the output terminal of the first voltage collector, the output terminal of the second voltage collector, and the output terminal of the third voltage collector, respectively. The output terminal of the analog-to-digital converter is connected to the first controller, and the display is connected to the first controller.

[0018] Optionally, the voltage surge detection unit includes:

[0019] DC voltage generator, charging capacitor, electronic control switch, first peak inrush current acquisition unit, second peak inrush current acquisition unit, second controller;

[0020] The output terminal of the DC voltage generator is connected to one end of the charging capacitor and the first end of the electronic control switch, respectively. The other end of the charging capacitor is grounded, and the other end of the electronic control switch is connected to the open side of the branch. The first inrush current peak acquisition device is located on the open side and is used to acquire the first current peak value. The second inrush current peak acquisition device is located on the neutral point side and is used to acquire the second current peak value.

[0021] The second controller is connected to the control terminal of the electric control switch, the first peak current collector, and the second peak current collector, respectively, and is used to acquire the first peak current and the second peak current to detect the winding insulation fault when the electric control switch is turned on.

[0022] Optionally, the electrically controlled switch is a controllable ball gap.

[0023] Optionally, the open transformer detection unit further includes:

[0024] An isolation transformer and a voltage regulator are provided, wherein the output side of the isolation transformer is coupled to the primary side of the voltage regulator, and the secondary side of the voltage regulator is connected to one end of any branch of any phase of the stator winding of the synchronous generator, for providing a third AC current to the branch.

[0025] An AC current collector is located on the secondary winding of the open-ended transformer and is used to collect the AC current of the secondary winding of the open-ended transformer; wherein, the two ends of the open-ended transformer can be moved against the surface of the stator core slot.

[0026] The third controller is connected to the AC current collector and is used to detect the winding insulation fault based on the AC current collected by the AC current collector.

[0027] Optionally, the secondary side of the voltage regulator is connected to both ends of any branch of any phase of the stator winding of the synchronous generator, for providing a third alternating current with varying amplitude to the branch.

[0028] To achieve the above objectives, a second aspect of the present invention provides a method for detecting insulation faults in a synchronous generator, implemented based on the synchronous generator insulation fault detection device described in any embodiment of the present invention, comprising the following steps:

[0029] Obtain the insulation resistance of any branch of any phase in the synchronous generator to ground;

[0030] The faulty branch is determined based on the magnitude of the insulation resistance, and the faulty bar within the branch is located.

[0031] Optionally, determining the faulty branch based on the magnitude of the insulation resistance and locating the faulty bar within the branch includes:

[0032] If the insulation resistance is less than or equal to a preset value, control any one of the following detection units—the DC voltage drop detection unit, the voltage surge detection unit, or the open transformer detection unit—to start fault location detection.

[0033] If the insulation resistance is greater than the preset value, the voltage surge detection unit is activated. After a discharge occurs, the open transformer detection unit or the DC voltage drop detection unit is activated to perform fault location detection.

[0034] According to an embodiment of the present invention, a synchronous generator insulation fault detection device and method are provided. The synchronous generator includes windings, which may be stator windings or rotor windings. The insulation fault detection device includes one or more of the following: a DC voltage drop detection unit, a voltage surge detection unit, or an open-circuit transformer detection unit. The DC voltage drop detection unit provides a constant DC current to the output side and neutral point side of any branch of any phase in the winding. When the current flows through the branch, a third voltage is generated at both ends. Based on the first voltage between the output side and the ground side of the branch, the second voltage between the neutral point side and the ground side of the branch, and the third voltage, [further details are needed]. The system includes several detection methods: a winding insulation fault detection unit and a voltage impulse detection unit. The voltage impulse detection unit provides a third DC current to the output side of any branch of any phase in the winding and detects winding insulation faults based on the first current peak value at the branch's output side and the second current peak value at the neutral point side, or by the discharge phenomenon occurring in the branch. An open-type transformer detection unit provides a third AC current to the output side of any branch of any phase in the stator winding and detects stator winding insulation faults based on the induced current in the secondary winding of the open-type transformer. The core of the open-type transformer is located in the stator core slot and is coupled to the stator core to form a current transformer. Therefore, by using the above detection devices and methods, the fault location can be quickly determined when a synchronous generator malfunctions, helping workers to perform timely repairs, reducing power outage time, and minimizing losses.

[0035] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a block diagram of the synchronous generator insulation fault detection device proposed in an embodiment of the present invention;

[0038] Figure 2 This is a schematic diagram of the DC voltage drop detection unit in the synchronous generator insulation fault detection device proposed in this embodiment of the invention.

[0039] Figure 3 This is a schematic diagram of the voltage impulse detection unit in the synchronous generator insulation fault detection device proposed in this embodiment of the invention;

[0040] Figure 4 This is a schematic diagram of the open transformer detection unit in the synchronous generator insulation fault detection device proposed in this embodiment of the invention.

[0041] Figure 5 This is a block diagram of the DC voltage drop detection unit in the synchronous generator insulation fault detection device proposed in this embodiment of the invention;

[0042] Figure 6 This is a block diagram of the DC voltage drop detection unit in a synchronous generator insulation fault detection device according to an embodiment of the present invention;

[0043] Figure 7 This is a topology diagram of the DC voltage drop detection unit in a synchronous generator insulation fault detection device according to an embodiment of the present invention;

[0044] Figure 8 This is a branch diagram of the stator winding of the generator in the synchronous generator insulation fault detection device proposed in this embodiment of the invention;

[0045] Figure 9 This is a display diagram of the detection results of the DC voltage drop detection unit of the generator in the synchronous generator insulation fault detection device proposed in this embodiment of the invention;

[0046] Figure 10 This is a schematic diagram of the voltage impulse detection unit in a synchronous generator insulation fault detection device according to an embodiment of the present invention;

[0047] Figure 11 This is a topology diagram of the voltage impulse detection unit in a synchronous generator insulation fault detection device according to an embodiment of the present invention;

[0048] Figure 12 This is a schematic diagram of the open transformer detection unit in a synchronous generator insulation fault detection device according to an embodiment of the present invention;

[0049] Figure 13 This is a topology diagram of the open transformer detection unit in a synchronous generator insulation fault detection device according to an embodiment of the present invention. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0051] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0052] Figure 1 This is a block diagram of the synchronous generator insulation fault detection device proposed in an embodiment of the present invention.

[0053] The synchronous generator includes windings, which can be stator windings or rotor windings; for example... Figure 1 As shown, the insulation fault detection device includes:

[0054] One or more of the following: DC voltage drop detection unit 101, voltage surge detection unit 102, or open transformer detection unit 103;

[0055] The DC voltage drop detection unit 101 is used to provide a constant DC current to the outlet side 201 and the neutral point side 202 of any branch 300 of any phase in the winding. When the current flows through the branch, a third voltage is generated at both ends. The winding insulation fault is detected based on the first voltage between the outlet side 201 and the ground side 203 of the branch 300, the second voltage between the neutral point side 202 and the ground side 203 of the branch 300, and the third voltage.

[0056] The voltage impulse detection unit 102 is used to provide a third DC current to the output side 201 of any branch 300 of any phase in the winding, and to detect winding insulation faults based on the first current peak value of the output side 201 of the branch 300 and the second current peak value of the neutral point side 202, and / or the discharge phenomenon that occurs in the branch 300.

[0057] The open-ended transformer detection unit 103 is used to provide a third AC current to the output side 201 of any branch 300 of any phase in the stator winding, and to detect stator winding insulation faults based on the induced current of the secondary winding of the open-ended transformer 104 in the open-ended transformer detection unit 103; wherein, the core of the open-ended transformer 104 is located in the stator core slot and is coupled with the stator core to form a current transformer.

[0058] It is understandable that the insulation fault detection device can detect faults in the synchronous generator through one or more of the three fault detection units.

[0059] If the DC voltage drop detection unit 101 is used for detection, the principle is as follows: Figure 2As shown, voltages can be supplied to the output side 201 and neutral point side 202 of any branch 300 in the winding, i.e., a DC current can be supplied to the branch 300. This allows for the measurement of the voltage between the output side 201 and ground, the voltage between the neutral point side 202 and ground, and the voltage between the output side 201 and neutral point side 202. If the branch 300 is not faulty, the voltage between the output side 201 and neutral point side 202 is U3, then the voltage between the output side 201 and ground is U1 (0V), and the voltage between the neutral point side 202 and ground is U2 (U3), or the voltage between the neutral point side 202 and ground is U2 (0V), and the voltage between the output side 201 and ground is U1 (U3). If the branch 300 is faulty, there is a grounding resistance between the faulty part of the branch 300 and ground; therefore, neither the voltage between the output side 201 and ground (U1) nor the voltage between the neutral point side 202 and ground (U2) is 0V. Therefore, when both the voltage U1 to ground on the output side 201 and the voltage U2 to ground on the neutral point side 202 are not 0V, a synchronous generator fault can be identified. Furthermore, the fault location of the faulty branch can be determined based on the obtained voltages U1 to ground on the output side 201 and U2 to ground on the neutral point side 202. Additionally, the position of the conductor in the faulty branch can be located based on the ratio of the voltages U1 to ground on the output side 201 and U2 to ground on the neutral point side 202 to the voltage U3 between the output side 201 and the neutral point side 202.

[0060] When using voltage surge detection unit 102 for detection, the principle is as follows: Figure 3 As shown, a third DC current is supplied to the output side 201 of any branch 300 in any phase of the winding. If the branch 300 is not faulty, the current supplied to the output side 201 is I3, the detected current I1 at the output side 201 is I3, and the current I2 at the neutral point side 202 is not zero. If the branch 300 is faulty, the detected current I1 at the output side 201 is I3, and the current I2 at the neutral point side 202 is zero, meaning that a part of the middle of the branch 300 is grounded, causing current to flow from the middle of the branch 300 to the ground, resulting in I2 being zero. Therefore, whether the current I2 at the neutral point side 202 is zero can be used to determine whether the branch 300 is faulty. In addition, when the third DC current is applied to the branch 300, if the branch 300 is not faulty, there will be no discharge phenomenon; if the branch 300 is faulty, there will be a discharge sound or discharge spark to locate the fault location. In one embodiment, the fault of branch 300 can be determined by whether the current I2 on the neutral point side 202 is 0, and the fault location can be located by discharge phenomena or sound.

[0061] When using the open-face transformer detection unit 103 for detection, the principle is as follows: Figure 4As shown, a third AC current is supplied to the output side 201 of any branch 300 of any phase in the winding. The opening of the open transformer 104 is coupled to the slot of the stator core to form a current transformer. The stator core and the branch winding on the core form the primary winding of the current transformer, and the winding on the open transformer 104 forms the secondary winding. When the branch 300 is not faulty, no induced current is induced in the secondary winding of the open transformer 104. When the branch 300 is faulty, the branch 300 is connected to the ground grid, and the current flows into the ground grid through the fault point and the stator core. As a result, the secondary winding of the open transformer 104 can be induced. Therefore, whether the branch is faulty and the fault location can be determined by whether there is an induced current in the secondary winding of the open transformer 104.

[0062] It should be noted that the DC voltage drop detection unit 101 is mainly capable of detecting and locating faults with low resistance to ground. When the resistance to ground is high, it is impossible to locate the faulty branch using a simple voltage ratio. Therefore, the voltage surge detection unit 102 can be used first to discharge the fault location on the branch to reduce the resistance to ground, and then the DC voltage drop detection unit 101 can be used to locate the fault. In other words, the various detection units complement each other and can also serve as a method of mutual verification.

[0063] The composition of each detection unit will be described below.

[0064] Optionally, such as Figure 2 , Figure 5 , Figure 6 and Figure 7 As shown, the DC voltage drop detection unit 101 includes:

[0065] The first voltage acquisition unit 401 is located between the output side 201 and the ground side 203 of any branch 300 of any phase in the winding, and is used to acquire the first voltage U1.

[0066] The second voltage acquisition unit 402 is located between the neutral point side 202 and the ground side 203 of any branch 300 of any phase in the winding, and is used to acquire the second voltage U2.

[0067] The third voltage acquisition unit 403 is located at both ends of the output side 201 and the neutral point side 202 of any branch 300 of any phase in the winding, and is used to acquire the third voltage U3.

[0068] The DC current source 404 is electrically connected to the output side 201 and the neutral point side 202 of any branch 300 of any phase in the winding.

[0069] The first controller 405 is connected to the first voltage collector 401, the second voltage collector 402, the third voltage collector 403, and the DC current source 404 respectively. It is used to determine the winding insulation fault when the sum of the first voltage U1 and the second voltage U2 is the third voltage U3, and the absolute values ​​of the first voltage U1 and the second voltage U2 are both greater than 0.

[0070] The first controller 405 is also used to calculate the ratio between the absolute value of the first voltage U1 and the sum of the absolute values ​​of the first voltage U1 and the second voltage U2, and to obtain the location of the faulty bar by combining the total number of bars X of the branch.

[0071] The main function of the DC current source 404 is to provide a DC output current to the branch of the generator stator winding to be tested. The DC current source 404 outputs current (adjustable range of 10A, 20A, 50A, 100A) to a specific branch of a phase of the generator stator winding.

[0072] In other words, when the first voltage U1 is not 0 and the second voltage U2 is not U3, or when the second voltage U2 is not 0 and the first voltage U1 is not U3, that is, when both the first voltage U1 and the second voltage U2 are not 0, then the branch is determined to be faulty, and this can be determined using Ohm's law. To locate the fault. Where X1 represents the DC resistance from the fault point to the generator outlet, X2 represents the DC resistance from the fault point to the generator neutral point, X represents the DC resistance from the outlet side to the neutral point side, and R represents the grounding resistance.

[0073] When the grounding resistance R is small and the internal resistance of the voltmeter is large enough, U1 + U2 ≈ U3.

[0074] Therefore, when |U1|+|U2|≈|U3|, U1≠0 and U2≠0, a metallic grounding fault can be identified on that branch; when U1≠0=U3, U2=0 or U2≠0=U3, U1=0, the fault on that branch can be ruled out. During fault location, calculations can be performed using pre-designed software embedded in the device unit, directly obtaining fault diagnosis results through testing and software computation.

[0075] like Figure 6 and Figure 7 As shown, the DC voltage drop detection unit 101 also includes an analog-to-digital converter 406 and a display 407. The input terminal of the analog-to-digital converter 406 is connected to the output terminal of the first voltage collector 401, the output terminal of the second voltage collector 402, and the output terminal of the third voltage collector 403, respectively. The output terminal of the analog-to-digital converter 406 is connected to the first controller 405, and the display 407 is connected to the first controller 405.

[0076] The analog-to-digital converter 406 converts the analog voltages collected by each voltage acquisition unit into digital voltages for calculation by the first controller 405. Furthermore, after the first controller 405 calculates the fault result, it can display it on the display screen 407. Specifically, it can display the percentage of winding bars with grounding faults output by the first controller 405, the fault location bar number, and the recommended bar number to be investigated. It is understood that the first controller 405 has a corresponding data acquisition and processing unit.

[0077] The following example demonstrates the practical application of this method.

[0078] E1 (E11, E12, E13) refers to the outlet-side connection point of a branch of a certain phase (A, B, C) of a generator in a power plant. S11, S12, and S13 are the neutral-point connection points of a branch of a certain phase (A, B, C) of the generator. In the generator stator winding, multiple branches are connected in parallel.

[0079] like Figure 8 The diagram shown is of the B-phase winding of the generator in this plant. E21, E22, and E23 are the E2 terminals on the generator output side. In actual connection, these three are welded together by copper busbars. S21, S22, and S23 are the S2 terminals on the generator neutral point side. In actual connection, they are connected together by screws and copper busbars and can be disassembled (in some generator branches, they cannot be disassembled).

[0080] When a fault occurs in phase B of the plant, if E2 (E21, E22, E23) and S21 are selected, the current-carrying circuit for the DC resistance test follows the uppermost branch. When the DC voltage U1 of E2 (E21, E22, E23) to ground, the DC voltage U2 of S21 to ground, and the voltage U3 between E2 (E21, E22, E23) and S21 are measured, the percentage of the grounding point relative to the entire winding length, U1 / (U1+U2), can be calculated using the formula. Multiplying this percentage by the total number of bars in that branch, X, gives the number of bars X1 or X2 that the fault location is from the outlet or from the neutral point. Then, the faulty bar number can be determined by combining this with the stator winding unfolding diagram.

[0081] Because the actual generator's conductors are connected by copper busbars, this calculated value may have some deviation. Therefore, the software's suggested troubleshooting locations also include the preceding and following numbers of the faulty conductor we identified. Display screen 407 displays the following content: Figure 9 As shown.

[0082] Optionally, such as Figure 10 and 11 As shown, the voltage surge detection unit 102 includes:

[0083] DC voltage generator 501, charging capacitor 502, electronic control switch 503, first inrush current peak acquisition device 504, second inrush current peak acquisition device 505, second controller 506;

[0084] The output terminal of DC voltage generator 501 is connected to one end of charging capacitor 502 and the first end of electronic control switch 503, respectively. The other end of charging capacitor 502 is grounded, and the other end of electronic control switch 503 is connected to the opening side 201 of branch 300. The first inrush current peak acquisition device 504 is located on the opening side 202 of branch 300 and is used to acquire the first current peak value I1. The second inrush current peak acquisition device 505 is located on the neutral point side 202 of branch 300 and is used to acquire the second current peak value I2.

[0085] The second controller 506 is connected to the control terminal of the electric control switch 503, the first peak current collector 504, and the second peak current collector 505, respectively. It is used to acquire the first peak current and the second peak current to detect winding insulation faults when the electric control switch 503 is turned on.

[0086] Optionally, the electronic switch 503 is a controllable ball gap.

[0087] This unit 102 is primarily used for locating non-metallic grounding faults or for precise physical location determination after the DC voltage drop detection unit 101 has located the fault. Specifically, when a high-resistivity grounding fault occurs in the generator and the DC voltage drop detection unit 101 cannot perform the location test, or when a precise fault location needs to be determined after the DC voltage drop detection unit 101 has performed the test, a high voltage is applied to the faulty branch winding to generate discharge sounds, sparks, and pulse currents in the winding at the grounding fault location, helping maintenance personnel quickly locate the grounding fault. This unit 102 also includes auxiliary components such as an instrument panel and a chassis to ensure convenient operation and safe transportation.

[0088] DC voltage generator 501 primarily generates an adjustable high-voltage DC output, which is sent to charging capacitor 502 to charge it and provide energy for high-voltage surges. Charging capacitor 502 primarily receives and stores energy from the DC high-voltage generator, discharging it under the control of a controllable ball gap. The controllable ball gap is a switch that adjusts the discharge voltage, discharging the high voltage under the control of a second controller 506. The high-voltage cable provides an electrical path for discharging the high-voltage DC from the capacitor to the high resistance of the generator, ensuring insulation to ground and other equipment under high voltage. Surge current peak acquisition devices 504 / 505 are used to collect the peak discharge current flowing through the generator stator windings during capacitor discharge. This current is discharged from the high-voltage capacitor, passes through the high-voltage cable and generator windings, and flows to the grounding grid through the stator core at the fault point. Peak current acquisition is achieved using a flexible coil clamp-on ammeter with a "hold" function to obtain the highest peak current value. Peak current acquisition devices are installed at both ends of a stator bar to qualitatively determine whether a fault exists in the winding. The first current peak acquisition unit 504 can feed back to the second controller 506 to adjust the size of the controllable ball gap, and the second current peak acquisition unit 505 can feed back to the second controller 506 to determine whether there is a fault in the branch.

[0089] It should be noted that when a ground fault occurs in the generator stator or rotor windings, there is generally no direct electrical connection between the conductors and the ground; a tiny gap exists between the conductor at the fault point and the grounding electrode. When the energy stored in the capacitor is released through the controllable spherical gap, a gap discharge occurs at the fault point, producing a discharge sound and sparks. This helps maintenance personnel quickly locate the fault, facilitating the development of maintenance strategies and reducing equipment downtime. Simultaneously, during energy release, an inrush current is generated in the windings. By testing the peak current at the upper and lower ends of a stator bar using a flexible clamp-on ammeter, maintenance personnel can qualitatively determine whether that bar is faulty. This method is particularly effective for faults where the discharge sparks cannot be directly observed.

[0090] To prevent high-voltage surges from damaging the generator stator core, the voltage should be initially low and then gradually increased when using this device for fault location. Once a clear discharge phenomenon is observed, the voltage should not be increased further.

[0091] Optionally, such as Figure 10 As shown, the open transformer detection unit 103 also includes:

[0092] Isolation transformer 601 and voltage regulator 602, the output side of isolation transformer 601 is coupled to the primary side of voltage regulator 602, and the secondary side of voltage regulator 602 is connected to one end of any branch of any phase of the stator winding of synchronous generator, for providing a third AC current to branch 300.

[0093] An AC current collector 603 is located on the secondary winding of an open-ended transformer 104 and is used to collect the AC current of the secondary winding of the open-ended transformer 104; wherein, the two ends of the open-ended transformer 104 can be moved against the surface of the stator core slot.

[0094] The third controller 604 is connected to the AC current collector 603 and is used to detect winding insulation faults based on the AC current collected by the AC current collector 603.

[0095] Optionally, the secondary side of the voltage regulator 602 is connected to both ends of any branch of any phase of the stator winding of the synchronous generator to provide a third alternating current with varying amplitude to branch 300.

[0096] The isolation transformer 601 primarily isolates the device from the power supply, preventing power supply tripping caused by direct current output to a ground fault. The voltage regulator 602 adjusts the device's output voltage to control the output current, preventing damage to the generator stator core during testing. The current acquisition unit on the voltage regulator 602 detects the voltage and current parameters output to the generator windings, facilitating adjustments to the output voltage and current by maintenance personnel as needed. Simultaneously, the current value detected from the secondary winding of the open transformer 104 helps pinpoint the fault location.

[0097] The open-end transformer 104 is used for coupling in the slot section of the generator stator core, and together with the core and the conductor bars in the slot, it forms a current transformer, and detects the current flowing through the conductor bars and outputs it to the AC current acquisition unit 603 of the open-end transformer 104.

[0098] The device may also include an insulating rod for securing the open-end transformer, facilitating safe operation, movement, and testing by maintenance personnel. It also includes auxiliary components such as test cables, instrument panels, and chassis to ensure ease of operation, human-machine interaction, and safe transportation.

[0099] The open-type transformer detection unit 103 has wider adaptability to different stator grounding faults. Its main principle involves coupling an open-type transformer 104 with the generator stator core to form a current transformer. The open core of the open-type transformer 104 and the generator stator core form a magnetic circuit. The conductors in the coupled stator core slots serve as the primary coil of the current transformer, while the coil on the open-type transformer 104 serves as the secondary coil. When an AC source within the detection unit is applied to the generator grounding fault branch, the current flows through the fault point and into the grounding grid via the core. The current can be detected at the secondary coil of the open-type transformer coupled to the core. As the open-type transformer moves up and down within the stator core slots, the point where the detected current disappears is the fault point, allowing for quick location of the generator grounding fault.

[0100] In the above embodiments, the current acquisition device is an ammeter, and the voltage acquisition device is a voltmeter. Therefore, by using the DC voltage drop detection unit 101, the voltage surge detection unit 102, and the open transformer detection unit 103 in combination, it is possible to quickly locate and confirm the insulator breakdown fault of a large synchronous generator.

[0101] This invention also proposes a method for detecting insulation faults in synchronous generators, implemented using a synchronous generator insulation fault detection device based on any embodiment of this invention, comprising the following steps:

[0102] Obtain the insulation resistance of any branch of any phase in a synchronous generator to ground; this can be detected using a megohmmeter. If the insulation resistance does not meet the standard for branch resistance, it is estimated that the branch may be faulty.

[0103] The faulty branch is determined based on the magnitude of the insulation resistance, and the faulty bar within that branch is located.

[0104] Optionally, the faulty branch is determined based on the magnitude of the insulation resistance, and the faulty bar within the branch is located, including:

[0105] If the insulation resistance is less than or equal to the preset value, control any one of the following detection units to start fault location detection: DC voltage drop detection unit, voltage surge detection unit, or open transformer detection unit.

[0106] If the insulation resistance is greater than the preset value, the control voltage surge detection unit will be activated. After a discharge phenomenon occurs, the control open transformer detection unit or DC voltage drop detection unit will be activated to perform fault location detection.

[0107] Understandably, the preset value can be in the kilohm level. For values ​​greater than kilohm, the voltage surge detection unit can be activated first to reduce the fault resistance, followed by the DC voltage drop detection unit for fault detection. For values ​​less than or equal to kilohm, any one of the following detection units can be used for detection and location: DC voltage drop detection unit, voltage surge detection unit, or open transformer detection unit. This method can be used to detect stator winding faults. When detecting rotor winding faults, for values ​​greater than kilohm, the voltage surge detection unit can be activated first to reduce the fault resistance, followed by the DC voltage drop detection unit for fault detection. For values ​​less than or equal to kilohm, either the DC voltage drop detection unit or the voltage surge detection unit can be used for detection.

[0108] In other embodiments, the voltage surge detection unit can also be activated after the DC voltage drop detection unit for further localization. The three detection units can verify each other and serve as backup units. The detection principles of the three detection units have been detailed in the device section and will not be repeated here.

[0109] In summary, according to the synchronous generator insulation fault detection device and method proposed in the embodiments of the present invention, the synchronous generator includes a winding, which is a stator winding or a rotor winding; the insulation fault detection device includes one or more of the following: a DC voltage drop detection unit, a voltage surge detection unit, or an open transformer detection unit; wherein, the DC voltage drop detection unit is used to provide a constant DC current to the output side and neutral point side of any branch of any phase in the winding, which generates a third voltage at both ends when flowing through the branch, and determines the voltage based on the first voltage between the output side and the ground side of the branch, the second voltage between the neutral point side and the ground side of the branch, and the third voltage. The system employs a voltage detection method to detect winding insulation faults. A voltage surge detection unit provides a third DC current to the output side of any branch of any phase in the winding and detects winding insulation faults based on the first current peak at the branch's output side and the second current peak at the neutral point, or by detecting discharge phenomena in the branch. An open-circuit transformer detection unit provides a third AC current to the output side of any branch of any phase in the stator winding and detects stator winding insulation faults based on the induced current in the secondary winding of the open-circuit transformer within the detection unit. The core of the open-circuit transformer is located in the stator core slot and coupled with the stator core to form a current transformer. Therefore, by using the above detection devices and methods, the fault location can be quickly determined when a synchronous generator malfunctions, helping workers to perform timely repairs, reducing power outage time, and minimizing losses.

[0110] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0111] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An apparatus for detecting an insulation fault in a synchronous generator, the apparatus comprising: The synchronous generator comprises a winding, which is a stator winding or a rotor winding; the insulation fault detection device comprises: one or more of a DC voltage drop detection unit, a voltage impulse detection unit or an open transformer detection unit; The DC voltage drop detection unit is configured to provide a constant DC current between the outlet side and the neutral point side of any branch of any phase of the winding, generate a third voltage across the branch when the current flows through the branch, and detect insulation faults of the winding according to a first voltage between the outlet side and the ground side of the branch, a second voltage between the neutral point side and the ground side of the branch, and the third voltage. The voltage impulse detection unit is configured to provide a third DC current to the outlet side of any branch of any phase of the winding, and detect insulation faults of the winding according to a first current peak value of the outlet side and a second current peak value of the neutral point side of the branch, and / or a discharge phenomenon occurring in the branch. The open transformer detection unit is configured to provide a third AC current to the outlet side of any branch of any phase of the stator winding, and detect insulation faults of the stator winding according to an induced current of a secondary winding of an open transformer in the open transformer detection unit; the core of the open transformer is located in a slot part of the stator core and is coupled with the stator core to form a current transformer.

2. The synchronous generator insulation fault detection apparatus of claim 1, wherein, The DC voltage drop detection unit comprises: a first voltage collector located between the outlet side and the ground side of any branch of any phase of the winding, configured to collect a first voltage; a second voltage collector located between the neutral point side and the ground side of any branch of any phase of the winding, configured to collect a second voltage; a third voltage collector located between the outlet side and the neutral point side of any branch of any phase of the winding, configured to collect a third voltage; a DC current source electrically connected to the outlet side and the neutral point side of any branch of any phase of the winding; a first controller connected to the first voltage collector, the second voltage collector, the third voltage collector and the DC current source, configured to determine insulation faults of the winding when the sum of the first voltage and the second voltage is the third voltage, and the absolute value of the first voltage and the absolute value of the second voltage are both greater than 0.

3. The synchronous generator insulation fault detection apparatus of claim 2, wherein, The first controller is further configured to calculate the ratio between the absolute value of the first voltage and the sum of the absolute value of the first voltage and the absolute value of the second voltage, and obtain the position of the faulty bar in combination with the total number of bars of the branch.

4. The synchronous generator insulation fault detection apparatus of claim 2 or 3, wherein Further comprising: an analog-to-digital converter and a display, the input end of the analog-to-digital converter is connected to the output end of the first voltage collector, the output end of the second voltage collector and the output end of the third voltage collector, the output end of the analog-to-digital converter is connected to the first controller, and the display is connected to the first controller.

5. The synchronous generator insulation fault detection apparatus of claim 1, wherein, The voltage impulse detection unit comprises: a DC voltage generator, a charging capacitor, an electrically controlled switch, a first impulse current peak collector, a second impulse current peak collector and a second controller. The output end of the direct current voltage generator is connected with one end of the charging capacitor and the first end of the electrically controlled switch respectively, the other end of the charging capacitor is grounded, the other end of the electrically controlled switch is connected with the opening side of the branch, the first impulse current peak value collector is located at the outlet side and is used for collecting the first current peak value, and the second impulse current peak value collector is located at the neutral point side and is used for collecting the second current peak value. The second controller is connected with the control end of the electrically controlled switch, the first impulse current peak value collector and the second impulse current peak value collector respectively, and is used for acquiring the first current peak value and the second current peak value to detect the winding insulation fault when the electrically controlled switch is turned on.

6. The synchronous generator insulation fault detection apparatus of claim 5, wherein, The electrically controlled switch is a controllable ball gap.

7. The synchronous generator insulation fault detection apparatus of claim 1, wherein, The open transformer detection unit further comprises: An isolation transformer and a voltage regulator, an output side of the isolation transformer is coupled with a primary side of the voltage regulator, and a secondary side of the voltage regulator is connected with one end of any branch of any phase of the stator winding of the synchronous generator, and is used for providing a third alternating current to the branch; An alternating current collector located on the secondary winding of the open transformer, and is used for collecting the alternating current of the secondary winding of the open transformer; wherein the two ends of the open transformer can be attached to the surface of the stator core slot part and moved; A third controller connected with the alternating current collector, and is used for detecting the insulation fault of the stator winding according to the alternating current collected by the alternating current collector.

8. The synchronous generator insulation fault detection apparatus of claim 7, wherein, The secondary side of the voltage regulator is connected with both ends of any branch of any phase of the stator winding of the synchronous generator, and is used for providing a third alternating current with a variable amplitude to the branch.

9. A method of detecting an insulation fault in a synchronous generator, the method comprising: The synchronous generator insulation fault detection device based on any one of claims 1-8 comprises the following steps: Obtaining the insulation resistance of any branch of any phase of the synchronous generator to the ground; Determining the branch with a fault according to the size of the insulation resistance, and locating the bar with a fault in the branch.

10. The synchronous generator insulation fault detection method of claim 9, wherein, The determination of the branch with a fault according to the size of the insulation resistance and the location of the bar with a fault in the branch comprise: If the insulation resistance is less than or equal to a preset value, controlling any one of the direct current voltage drop detection unit, the voltage impulse detection unit or the open transformer detection unit to start the fault location detection; If the insulation resistance is greater than the preset value, controlling the voltage impulse detection unit to start, and then controlling the open transformer detection unit or the direct current voltage drop detection unit to start the fault location detection after the discharge phenomenon occurs.

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