Sealing tile insulation impedance test method and circuit

Abstract

The present invention discloses a sealing shoe insulation impedance test method and circuit, which are used to measure the insulation impedance of the insulating sealing shoe to the ground provided on the main shaft of the generator, and the method comprises: performing inductive load increase processing on the first shaft body of the main shaft; obtaining first AC data on the first shaft body and second AC data on the second shaft body of the main shaft when the main shaft is in an AC power-on state to the ground; and calculating the insulation impedance of the insulating sealing shoe to the ground according to the first AC data and the second AC data. The implementation of the present invention can realize the accurate measurement of the insulation impedance of the insulating sealing shoe to the ground without removing the wheels between the generator and the steam turbine, and the test method is simple and efficient, which can greatly reduce the workload and construction period of nuclear power plant overhaul and improve the economic benefits of nuclear power plants.

Description

Technical Field

[0001] The invention relates to the technical field of electrical equipment detection, and in particular to a sealing tile insulation impedance testing method and circuit. Background Art

[0002] In a nuclear power plant, the overhaul must measure the insulation resistance to ground on the exciter side of the generator. Figure 2 As shown in the figure, the No. 7 and No. 8 sealing pads of the generator are made of insulating materials, which are used to keep the insulation between the pads and the ground, thereby preventing the failure of the pads during operation and the burning of the bearings by the circulating current. However, the No. 1 to No. 6 sealing pads are not made of special insulating materials, and they rely on oil for insulation during operation. However, during the overhaul, the supply of bearing oil was stopped, so the No. 1 to No. 6 sealing pads were all grounded. This makes it particularly difficult to measure the insulation impedance of the No. 7 and No. 8 sealing pads to the ground. The counterwheel between the generator and the steam turbine must be disconnected, otherwise the main shaft of the generator rotor is connected to the main shaft of the steam turbine through the counterwheel, making the insulation impedance to the ground on the exciter side approximately zero.

[0003] Disconnecting the wheels is a very labor-intensive task. Not only does it take four workers more than 20 hours to do this, but one of the two rotors must be pushed apart axially and then pushed back after the insulation measurement is completed. There is a risk of asymmetry between the turbine and generator rotor axes after reconnection. It may take several days to find the center symmetry point again, greatly increasing the overhaul period. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a sealing tile insulation impedance testing method and circuit in view of at least one defect in the prior art.

[0005] The technical solution adopted by the present invention to solve the technical problem is: construct a sealing shoe insulation impedance test method for measuring the insulation impedance of the insulating sealing shoe arranged on the main shaft of the generator to the ground, comprising the following steps:

[0006] S1, performing induction load increasing processing on the first shaft body of the main shaft; the first shaft body is the shaft body of the main shaft close to the first outlet side of the insulating sealing tile and between the grounding sealing tile;

[0007] S2, when the main shaft is in an AC power-on state, obtaining first AC data on the first shaft body and second AC data on the second shaft body of the main shaft; the second shaft body is the shaft body of the main shaft near the second outlet side of the insulating sealing shoe;

[0008] S3. Calculate the insulation impedance of the insulating sealing tile to ground based on the first AC data and the second AC data.

[0009] Preferably, in S1, the inductive loading process includes: increasing the AC impedance of the large shaft based on the principle of electromagnetic induction.

[0010] Preferably, in S1, increasing the AC impedance of the first shaft includes: providing a preset magnetic permeability member on the outer periphery of the first shaft.

[0011] Preferably, the preset magnetic conductor comprises a magnetic conductor and an induction winding provided on the trunk of the magnetic conductor and having a preset static impedance.

[0012] Preferably, in S2, the first AC data includes a first AC current, and the second AC data includes a second AC current and an AC voltage.

[0013] Preferably, in S3, the calculation expression of the insulation resistance to ground is:

[0014] Rx = U2 / (I2-I1);

[0015] Among them, Rx is the insulation impedance to ground, U2 is the AC voltage, I2 is the second AC current, and I1 is the first AC current.

[0016] Preferably, in S2, the second AC data further includes a phase angle between the second AC current and the AC voltage;

[0017] In S3, the calculation expression of the insulation resistance to ground is:

[0018]

[0019] Among them, Rx is the insulation impedance to ground, U2 is the AC voltage, I2 is the second AC current, I1 is the first AC current, and a is the phase angle.

[0020] The present invention also constructs a sealing shoe insulation impedance test circuit for measuring the insulation impedance of the insulating sealing shoe arranged on the main shaft of the generator to the ground, comprising:

[0021] An inductive load increasing unit is connected to the first shaft body of the main shaft and is used to perform inductive load increasing processing on the first shaft body; the first shaft body is the shaft body of the main shaft close to the first outlet side of the insulating sealing tile and between the grounding sealing tile;

[0022] A signal acquisition unit connected to the main shaft, used for collecting first AC data on the first shaft body and second AC data on the second shaft body of the main shaft when the main shaft is in an AC power-on state; the second shaft body is the shaft body of the main shaft close to the second outlet side of the insulating sealing shoe;

[0023] The impedance calculation unit is connected to the signal acquisition unit and is used to calculate the insulation impedance of the insulating sealing tile to the ground according to the first AC data and the second AC data.

[0024] Preferably, the sealing shoe insulation impedance test circuit further comprises a high-frequency power supply connected to the signal acquisition unit, for providing an AC voltage to the large shaft;

[0025] The inductive load-increasing unit comprises a magnetic conductor and an inductive winding which is arranged on the trunk of the magnetic conductor and has a preset static impedance. The magnetic conductor is arranged on the outer periphery of the first shaft.

[0026] Preferably, the signal acquisition unit includes a first current acquisition unit for acquiring a first AC current in the first AC data, a second current acquisition unit for acquiring a second AC current in the second AC data, a voltage acquisition unit for acquiring an AC voltage in the second AC data, and a phase acquisition unit for measuring a phase angle of the second AC current and the AC voltage; the first current acquisition unit is connected to the first shaft, the second current acquisition unit and the voltage acquisition unit are connected to the second shaft, and the phase acquisition unit is connected to the second current acquisition unit and the voltage acquisition unit.

[0027] The present invention has at least the following beneficial effects: providing a method for testing the insulation impedance of a sealing shoe: performing an inductive load increase process on the first shaft body of a main shaft; then obtaining the first AC data on the first shaft body and the second AC data on the second shaft body of the main shaft when the main shaft is in an AC-to-ground energized state; finally calculating the insulation impedance of the insulating sealing shoe to ground based on the first AC data and the second AC data; wherein the second shaft body is the shaft body of the main shaft close to the second outlet side of the insulating sealing shoe; the first shaft body is the shaft body of the main shaft close to the first outlet side of the insulating sealing shoe and between the grounding sealing shoe. The present invention can accurately measure the insulation impedance of the insulating sealing shoe to ground without removing the pair of wheels between the generator and the steam turbine, and the testing method is simple and efficient, which can greatly reduce the workload and construction period of nuclear power plant overhaul and improve the economic benefits of nuclear power plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0029] Figure 1 It is a flow chart of the sealing tile insulation impedance testing method provided by the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the main shaft of a generator in a nuclear power plant;

[0031] Figure 3It is a schematic diagram of an embodiment of the inductive loading process in the sealing tile insulation impedance testing method provided by the present invention;

[0032] Figure 4 It is a structural diagram of the sealing tile insulation impedance test circuit provided by the present invention;

[0033] Figure 5 It is an equivalent circuit diagram of the test process of the sealed tile insulation impedance test circuit provided by the present invention. DETAILED DESCRIPTION

[0034] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0035] It should be noted that the flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor do they have to be executed in the order described. For example, some operations / steps can be decomposed, while some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.

[0036] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities may be implemented in software form, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0037] refer to Figure 1 The present invention provides a sealing shoe insulation impedance testing method for measuring the insulation impedance of an insulating sealing shoe 8 arranged on a main shaft 1 of a generator to ground, comprising steps S1, S2 and S3.

[0038] Step S1 includes: performing an inductive load increase process on the first shaft body 11 of the large shaft 1 to increase the AC impedance of the first shaft body 11 when it is in an AC conduction state, in preparation for subsequent steps. Figure 2 The first shaft body 11 is the shaft body between the first outlet side 2 of the main shaft 1 close to the insulating sealing shoe 8 and the grounding sealing shoe 9. Figure 2 As shown, the insulating sealing tile 8 includes sealing tiles No. 7 and No. 8, and the grounding sealing tile 9 includes sealing tiles No. 1 to No. 6.

[0039] In some embodiments, in step S1, the inductive loading process includes: increasing the AC impedance of the large shaft 1 based on the electromagnetic induction principle. Further, in some embodiments, the AC impedance of the first shaft 11 increased in step S1 is as follows: Figure 2 As shown, a preset magnetic guide member 4 is arranged on the outer circumference of the first shaft body 11 .

[0040] In some embodiments, Figure 3 As shown, the preset magnetic conductor 4 includes a magnetic conductor 41 and an induction winding 42 provided on the trunk of the magnetic conductor 41 and having a preset static impedance. The magnetic conductor 41 is a collar that can be sleeved on the first shaft 11, and the collar is a material with good magnetic conductivity, such as an iron core, a cobalt core, a nickel core or an iron alloy. Preferably, the collar is a pair of semicircular iron core rings with a half-open structure, and the induction winding 42 is wound on one of the semicircular iron core rings, and the pair of semicircular iron core rings can be sleeved on the first shaft 11 by bolts.

[0041] refer to Figure 3 The principle of inductive load increase to increase the AC impedance of the main shaft 1 is as follows:

[0042] When the power supply is connected to the main shaft 1 so that it is connected to the ground, the power supply is connected to the ground through the first shaft body 11. At this time, the first shaft body 11 is equivalent to a primary winding L1 with a turn number of 1, and the coil L2 wound on the ring in the induction winding 42 is a secondary winding with a number of turns. The primary winding L1 and the secondary winding form an electrical structure similar to a transformer. Then, according to the proportional relationship between the voltage and current of the transformer and the turns ratio, the following formula (1) can be obtained: Formula (2): Formula (3): Formula (4): Then, according to formulas (1) to (4), formula (5) is derived: R21 = K 2 *R22; where U21 is the voltage of the primary winding L1, U22 is the voltage of the secondary winding, K is the turns ratio of the primary winding L1 to the secondary winding, I21 is the current of the primary winding, I22 is the current of the secondary winding, R21 is the AC impedance of the primary winding L1, and R22 is the AC impedance of the secondary winding; In addition, the derivation principle of formula (5) can also refer to Figure 5 .

[0043] It can be seen from formula (5) that when the main shaft 1 is in the state of AC power supply to the ground, it is equivalent to converting the AC impedance of the secondary winding to the primary winding L1 in proportion, so as to achieve the purpose of increasing the AC impedance of the first shaft body 11, so that the leakage current shunted to the insulating sealing tile 8 increases, which is beneficial to improve the measurement accuracy of the leakage current, and thus make the calculated insulation impedance of the insulating sealing tile 8 to the ground more accurate; taking K as 1 as an example, if R22 is 1K ohms, then R21 also corresponds to 1K ohms. At this time, even if a 500V AC power supply is applied to the main shaft 1, the current amplitude of the main shaft 1 is only 0.5A, and the internal resistance of the main shaft 1 itself is very small, generally in the milliohm level. Without increasing the AC impedance of the first shaft body 11, if the measured voltage is too high, the current flowing through the main shaft 1 will be too high, and if the measured voltage is low, the leakage current of the insulating sealing tile 8 will be too small, which is not conducive to measuring the insulation impedance of the insulating sealing tile 8 to the ground.

[0044] It can be understood that in some embodiments, such as Figure 3 As shown, the induction winding 42 includes a coil L2 and a preset resistor R3 connected in parallel with both ends of the coil L2; wherein the coil L2 is wound on the ring as a secondary winding, and the preset resistor R3 is used to set the preset static impedance of the induction winding 42 to achieve the effect of setting the AC impedance of the secondary winding.

[0045] Step S2 includes: when the main shaft 1 is in an AC power-on state, obtaining first AC data on the first shaft body 11 and second AC data on the second shaft body 12 of the main shaft 1. Figure 2 The second shaft body 12 is the shaft body of the second outlet side 3 of the main shaft 1 close to the insulating sealing shoe 8.

[0046] Step S3 includes: calculating the insulation impedance of the insulating sealing tile 8 to the ground according to the first AC data and the second AC data.

[0047] In some embodiments, the first AC data in step S2 includes a first AC current, and the second AC data includes a second AC current and an AC voltage.

[0048] Accordingly, refer to Figure 3 or Figure 5 According to Ohm's law, the calculation expression of the insulation resistance to ground in step S3 is: Rx=U2 / (I2-I1); wherein Rx is the insulation resistance to ground, U2 is the AC voltage (equivalent to the voltage across the equivalent resistance to ground), I2 is the second AC current (equivalent to the current flowing through the second shaft 12), and I1 is the first AC current (equivalent to the current flowing through the first shaft 11).

[0049] like Figure 5As shown, under high frequency conditions, the equivalent ground resistance and ground capacitance of the insulating sealing tile 8 are connected in parallel, wherein the ground capacitance is expressed as: C =1 / (2*3.14*f), where X C is the impedance of the capacitance to ground, and f is the power frequency. Although the impedance of the capacitance to ground decreases as the frequency increases, in order to further improve the measurement accuracy of the insulation impedance to ground, the impedance of the capacitance to ground cannot be ignored. The calculated insulation impedance to ground can be decomposed by measuring the phase angle between the second alternating current and the second alternating voltage. Therefore, in some embodiments, the second alternating current data in step S2 also includes the phase angle between the second alternating current and the alternating voltage.

[0050] Accordingly, the calculation expression of the insulation resistance to ground in step S3 is: Wherein, Rx is the insulation impedance to ground, U2 is the AC voltage, I2 is the second AC current, I1 is the first AC current, and a is the phase angle between the second AC current and the AC voltage.

[0051] refer to Figure 4 The present invention also provides a sealing shoe insulation impedance test circuit for measuring the insulation impedance of the insulating sealing shoe 8 arranged on the main shaft 1 of the generator to the ground, including a preset magnetic permeability 4, a signal acquisition unit 31 and an impedance calculation unit 32.

[0052] The preset magnetic guide member 4 is connected to the first shaft body 11 of the main shaft 1 for performing inductive load increasing processing on the first shaft body 11 ; the first shaft body 11 is the shaft body between the first outlet side 2 of the main shaft 1 close to the insulating sealing tile 8 and the grounding sealing tile 9 .

[0053] In some embodiments, the preset magnetic guide member 4 includes a magnetic conductor 41 and an induction winding 42 disposed on the trunk of the magnetic conductor 41 and having a preset static impedance. The magnetic conductor 41 is disposed on the outer periphery of the first shaft 11 .

[0054] In some embodiments, Figure 5 As shown, the induction winding 42 includes a coil L2 and a preset resistor R3 connected in parallel with both ends of the coil L2.

[0055] The signal acquisition unit 31 is connected to the main shaft 1, and is used to collect the first AC data on the first shaft body 11 and the second AC data on the second shaft body 12 of the main shaft 1 when the main shaft 1 is in the AC power-on state; the second shaft body 12 is the shaft body on the second outlet side 3 of the main shaft 1 close to the insulating sealing shoe 8.

[0056] In some embodiments, Figure 5As shown, the signal acquisition unit 31 includes a first current acquisition unit 311 for acquiring a first AC current in the first AC data, a second current acquisition unit 312 for acquiring a second AC current in the second AC data, a voltage acquisition unit 313 for acquiring an AC voltage in the second AC data, and a phase acquisition unit 314 for measuring a phase angle of the second AC current and the AC voltage; the first current acquisition unit 311 is connected to the first shaft 11, the second current acquisition unit 312 and the voltage acquisition unit 313 are connected to the second shaft 12, and the phase acquisition unit 314 is connected to the second current acquisition unit 312 and the voltage acquisition unit 313.

[0057] Furthermore, in some embodiments, Figure 5 As shown, the first current acquisition unit 311 includes a first current transformer CT1 and a first ammeter A1; the second current acquisition unit 312 includes a second current transformer CT2 and a second ammeter A2; the voltage acquisition unit 313 may be a voltmeter V1, and the phase acquisition unit 314 may be a phase meter C.

[0058] The impedance calculation unit 32 is connected to the signal acquisition unit 31 and is used to calculate the insulation impedance of the insulating sealing tile 8 to the ground according to the first AC data and the second AC data.

[0059] In some embodiments, Figure 4 As shown, the sealing shoe insulation impedance test circuit also includes a high-frequency power supply AC connected to the signal acquisition unit 31 for providing an AC voltage to the large shaft 1 .

[0060] It can be understood that the present invention performs inductive load increase processing on the first shaft body of the main shaft; then, when the main shaft is in an AC-to-ground energized state, obtains the first AC data on the first shaft body and the second AC data on the second shaft body of the main shaft; finally, the insulation impedance of the insulating sealing tile to the ground is calculated according to the first AC data and the second AC data; wherein, the second shaft body is the shaft body of the main shaft close to the second outlet side of the insulating sealing tile; the first shaft body is the shaft body of the main shaft close to the first outlet side of the insulating sealing tile and between the grounding sealing tile. The implementation of the present invention can realize the accurate measurement of the insulation impedance of the insulating sealing tile to the ground without removing the pair of wheels between the generator and the steam turbine, and the test method is simple and efficient, which can greatly reduce the workload and construction period of the nuclear power plant overhaul and improve the economic benefits of the nuclear power plant.

[0061] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the scope covered by the claims of the present invention.

Claims

1. A sealing shoe insulation impedance testing method, used to measure the insulation impedance of an insulating sealing shoe (8) provided on a main shaft (1) of a generator to ground, characterized in that: The following steps are involved: S1. Performing an inductive load increase process on the first shaft body (11) of the main shaft (1); the first shaft body (11) is the shaft body of the main shaft (1) close to the first outlet side (2) of the insulating sealing shoe (8) and between the main shaft (1) and the grounding sealing shoe (9); wherein the inductive load increase process comprises: increasing the AC impedance of the main shaft (1) based on the principle of electromagnetic induction; S2, when the main shaft (1) is in an AC power-on state, obtaining first AC data on the first shaft body (11) and second AC data on the second shaft body (12) of the main shaft (1); the second shaft body (12) is the shaft body of the main shaft (1) close to the second outlet side (3) of the insulating sealing shoe (8); S3. Calculate the insulation impedance of the insulating sealing tile (8) to ground based on the first AC data and the second AC data.

2. The sealing tile insulation impedance testing method according to claim 1, characterized in that: In the step S1, increasing the AC impedance of the first shaft (11) comprises: arranging a preset magnetic permeability member (4) on the outer periphery of the first shaft (11).

3. The sealing tile insulation impedance testing method according to claim 2, characterized in that: The preset magnetic guide member (4) comprises a magnetic conductor (41) and an induction winding (42) provided on the trunk of the magnetic conductor (41) and having a preset static impedance.

4. The sealing tile insulation impedance testing method according to any one of claims 1 to 3, characterized in that: In S2, the first AC data includes a first AC current, and the second AC data includes a second AC current and an AC voltage.

5. The sealing tile insulation impedance testing method according to claim 4, characterized in that: In S3, the calculation expression of the insulation resistance to ground is: ； in, is the insulation resistance to ground, is the AC voltage, is the second alternating current, is the first alternating current.

6. The sealing tile insulation impedance testing method according to claim 4, characterized in that: In S2, the second AC data further includes a phase angle between the second AC current and the AC voltage; In S3, the calculation expression of the insulation resistance to ground is: ； in, is the insulation resistance to ground, is the AC voltage, is the second alternating current, is the first alternating current, is the phase angle.

7. A sealing shoe insulation impedance test circuit, used for measuring the insulation impedance of an insulating sealing shoe (8) provided on a main shaft (1) of a generator to ground, characterized in that: include: A magnetic guide member (4) is provided, connected to a first shaft body (11) of the main shaft (1), and is used to perform an inductive load-increasing process on the first shaft body (11); the first shaft body (11) is a shaft body of the main shaft (1) close to a first outlet side (2) of the insulating sealing shoe (8) and between the main shaft (1) and the grounding sealing shoe (9); A signal acquisition unit (31) is connected to the main shaft (1) and is used to collect first AC data on the first shaft body (11) and second AC data on the second shaft body (12) of the main shaft (1) when the main shaft (1) is in an AC power-on state; the second shaft body (12) is the shaft body of the main shaft (1) close to the second outlet side (3) of the insulating sealing shoe (8); An impedance calculation unit (32) is connected to the signal acquisition unit (31) and is used to calculate the insulation impedance of the insulating sealing tile (8) to the ground based on the first AC data and the second AC data.

8. The sealing tile insulation impedance test circuit according to claim 7, characterized in that: The sealing shoe insulation impedance test circuit also includes a high-frequency power supply connected to the signal acquisition unit (31) and used to provide an AC voltage for the large shaft (1); The preset magnetic guide member (4) comprises a magnetic conductor (41) and an induction winding (42) provided on the trunk of the magnetic conductor (41) and having a preset static impedance; the magnetic conductor (41) is provided on the outer periphery of the first shaft (11).

9. The sealing tile insulation impedance test circuit according to claim 8, characterized in that: The signal acquisition unit (31) comprises a first current acquisition unit for acquiring a first alternating current in the first alternating current data, a second current acquisition unit for acquiring a second alternating current in the second alternating current data, a voltage acquisition unit for acquiring an alternating voltage in the second alternating current data, and a phase acquisition unit for measuring a phase angle between the second alternating current and the alternating voltage; the first current acquisition unit is connected to the first shaft (11), the second current acquisition unit and the voltage acquisition unit are connected to the second shaft (12), and the phase acquisition unit is connected to the second current acquisition unit and the voltage acquisition unit.

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