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: S1, performing excitation induction processing on the first shaft body of the main shaft to make the main shaft enter a predetermined state; 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; S2, obtaining AC data on the first shaft body in the predetermined state; S3, calculating the insulation impedance of the insulating sealing shoe to the ground based on the 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 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 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, the method comprising the following steps:

[0006] S1, performing excitation induction processing on the first shaft body of the main shaft to make the main shaft enter a predetermined state; 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 main shaft and the grounding sealing shoe;

[0007] S2. acquiring AC data on the first axis under the predetermined state;

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

[0009] Preferably, in S1, the excitation induction process includes: inputting an alternating magnetic field into the first shaft body, so that the large shaft acquires induction energy to enter an alternating current power-on state.

[0010] Preferably, in S1, inputting an alternating magnetic field into the first shaft includes: inputting an alternating voltage of a preset frequency into a preset induction element.

[0011] Preferably, the preset induction component includes a magnetic conductor and an induction winding arranged on the magnetic conductor.

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

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

[0014] Rx=U / I;

[0015] Wherein, Rx is the insulation impedance to ground, U is the induced voltage, and I is the induced current.

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

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

[0018]

[0019] Wherein, Rx is the insulation impedance to ground, U is the induced voltage, I is the induced 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 to the ground, and the circuit comprises:

[0021] an induction excitation unit connected to the first shaft body of the main shaft, and performing excitation induction processing on the first shaft body of the main shaft to make the main shaft enter a predetermined state; 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 main shaft and the grounding sealing shoe;

[0022] A signal acquisition unit connected to the main shaft, and used to collect AC data on the first shaft under the predetermined state;

[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 AC data.

[0024] Preferably, the induction excitation unit includes an AC power supply for outputting an induced voltage of a preset frequency, a magnetic conductor arranged on the outer periphery of the first shaft, and an induction winding arranged on the trunk of the magnetic conductor; the AC power supply is connected to the induction winding.

[0025] Preferably, the signal acquisition unit includes a current acquisition unit for acquiring the induced current in the AC data, a voltage acquisition unit for acquiring the induced voltage in the AC data, and a phase acquisition unit for measuring the phase angle of the induced current and the induced voltage; the current acquisition unit and the voltage acquisition unit are connected to the first shaft, and the phase acquisition unit is connected to the current acquisition unit and the voltage acquisition unit.

[0026] The present invention has at least the following beneficial effects: providing a method for testing the insulation impedance of a sealing shoe: by performing excitation induction processing on the first shaft body of the main shaft, the main shaft enters a predetermined state; then, in the predetermined state, the AC data on the first shaft body is obtained; finally, the insulation impedance of the insulating sealing shoe to the ground is calculated according to the AC data; wherein 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 implementation of the present invention can achieve accurate measurement of the insulation impedance of the insulating sealing shoe to the ground by using a single current acquisition unit 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

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0028] Figure 1 It is a flow chart of the sealing tile insulation impedance testing method provided by the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the main shaft of a generator in a nuclear power plant;

[0030] Figure 3 It is a schematic diagram of an embodiment of the excitation induction processing in the sealing tile insulation impedance testing method provided by the present invention;

[0031] Figure 4 It is a structural diagram of the sealing tile insulation impedance test circuit provided by the present invention;

[0032] 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

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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 arranged on a main shaft of a generator to ground. The method comprises step S1, step S2 and step S3.

[0037] Step S1 includes: performing excitation induction processing on the first shaft body 11 of the main shaft 1 to make the main shaft 1 enter a predetermined state. Figure 2 As shown, the first shaft body 11 is the shaft body between the first outlet side 2 of the large 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.

[0038] In some examples, the excitation induction process in step S1 includes: inputting an alternating magnetic field into the first shaft body 11 so that the large shaft 1 acquires induction energy to enter an AC power-on state, in preparation for the subsequent step S2.

[0039] In some embodiments, inputting the alternating magnetic field to the first shaft 11 in step S1 includes: inputting an alternating voltage of a preset frequency to a preset induction element, thereby generating an alternating magnetic field.

[0040] In some embodiments, Figure 3 As shown, the preset induction component 3 in step S1 includes a magnetic conductor 31 and an induction winding L1 arranged on the magnetic conductor 31; the induction winding L1 is used to receive an AC voltage of a preset frequency.

[0041] In some embodiments, Figure 3 As shown, the magnetic conductor 31 is a ring that can be sleeved on the first shaft 11, and the ring is made of a material with good magnetic conductivity, such as an iron core, a cobalt core, a nickel core or an iron alloy. Preferably, the ring is a pair of semicircular iron core rings with a half-open structure, and the induction winding L1 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.

[0042] refer to Figure 3 , the working principle of excitation induction processing is as follows:

[0043] The induction winding L1 is a primary winding with a number of turns, and the loop formed by the first shaft 11, the equivalent insulation resistance of the insulating sealing tile 8 and the ground is equivalent to forming a secondary winding L2 with a turn of 1. The primary winding and the secondary winding L2 form an electrical structure similar to a transformer. Therefore, an induced voltage can be input to the primary winding to make the secondary winding L2 generate a corresponding induced voltage, and then the equivalent insulation resistance of the insulating sealing tile 8 can be measured based on the induced voltage. Furthermore, according to the relationship between the induced voltage and the magnetic flux of the transformer, Ux=k*f*Nx*B*S(1), wherein Ux is the induced voltage of the winding on one side of the transformer, k is the coefficient (generally 4.44), f is the preset frequency, Nx is the number of turns of the winding on this side, B is the magnetic induction intensity, and S is the effective cross-sectional area of ​​the magnetic core.

[0044] Combined with formula (1), it can be seen that for the secondary winding L2, the number of turns is 1, and its induced voltage expression is: U L2 =k*f*B*S(2); From formula (2), we can know that the induced voltage U of the secondary winding L2 is L2 It is proportional to the preset frequency f, magnetic induction intensity B and effective cross-sectional area S. When the magnetic conductor 31 is an iron core, in order to prevent the iron core from entering a saturated state, the magnetic induction intensity B cannot exceed 1.5T. The increase in the effective cross-sectional area S will increase the weight and volume of the magnetic conductor 31. If the on-site installation is not used, the induced voltage of the secondary winding L2 can be controlled by adjusting the preset frequency f. In order to make the effective cross-sectional area S of the iron core used within an appropriate range and set the induced voltage of the secondary winding L2 to 500V, the preset frequency can be set to 1000 to 2000Hz. Further, from formula (1), it can be seen that for the primary winding, the expression of the induction intensity B is: B = U L1 / (k*f*N L1 *S), where U L1 is the AC voltage input to the induction winding L1, N L1 is the number of turns of the induction winding L1; when the coefficient k, the preset frequency f and the effective cross-sectional area S are determined, the U L1 and N L1 To adjust B.

[0045] Step S2 includes: acquiring AC data on the first shaft 11 in a predetermined state.

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

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

[0048] Accordingly, refer to Figure 3 or Figure 5 The calculation expression of the insulation resistance to ground in step S3 is: Rx=U / I; wherein Rx is the insulation resistance to ground, U is the induced voltage, and I is the induced current.

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

[0050] Accordingly, the calculation expression of the insulation resistance to ground in step S3 is: Among them, Rx is the insulation resistance to ground, U is the induced voltage, I is the induced current, and a is the phase angle between the induced current and the induced 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 to the ground. The circuit includes an induction excitation unit 41, a signal acquisition unit 42 and an impedance calculation unit 43.

[0052] The induction excitation unit 41 is connected to the first shaft body 11 of the main shaft 1, and performs excitation induction processing on the first shaft body 11 of the main shaft 1 to make the main shaft 1 enter a predetermined state; 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 tile 8 and between the grounding sealing tile 9.

[0053] In some embodiments, the induction excitation unit 41 includes an alternating current power supply AC for outputting an induction voltage of a preset frequency, a magnetic conductor 31 arranged on the periphery of the first shaft 11, and an induction winding L1 arranged on the trunk of the magnetic conductor 31; the alternating current power supply AC is connected to the induction winding L1.

[0054] The signal acquisition unit 42 is connected to the main shaft 1 and is used to collect AC data on the first shaft body 11 under a predetermined state.

[0055] In some embodiments, the signal acquisition unit 42 includes a current acquisition unit 421 for acquiring an induced current in the AC data, a voltage acquisition unit 422 for acquiring an induced voltage in the AC data, and a phase acquisition unit 422 for measuring the phase angle of the induced current and the induced voltage; the current acquisition unit 421 and the voltage acquisition unit 422 are connected to the first shaft 11, and the phase acquisition unit 422 is connected to the current acquisition unit 421 and the voltage acquisition unit 422. Figure 3 The voltage collection unit 422 can also collect the induced voltage by being connected to the shaft body of the main shaft 1 close to the side opposite to the first outlet side 2.

[0056] Furthermore, in some embodiments, Figure 5 As shown, the current acquisition unit 421 includes a current transformer CT1 and a first ammeter A1, the voltage acquisition unit may be a voltmeter V1, and the phase acquisition unit may be a phase meter C.

[0057] The impedance calculation unit 43 is connected to the signal acquisition unit 42 and is used to calculate the insulation impedance of the insulating sealing tile 8 to the ground according to the AC data.

[0058] It can be understood that the present invention performs excitation induction processing on the first shaft body of the main shaft to make the main shaft enter a predetermined state; then, in the predetermined state, the AC data on the first shaft body is obtained; finally, the insulation impedance of the insulating sealing tile to the ground is calculated according to the AC data; wherein, 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 achieve 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.

[0059] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, 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 coverage of 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 method comprises the following steps: S1. Performing an excitation induction process on the first shaft body (11) of the large shaft (1) so that the large shaft (1) enters a predetermined state; the first shaft body (11) is the shaft body of the large shaft (1) close to the first outlet side of the insulating sealing shoe (8) and between the grounding sealing shoe (9); the excitation induction process comprises: inputting an alternating magnetic field into the first shaft body (11) so that the large shaft (1) obtains induction energy to enter an alternating current energized state; S2. In the predetermined state, acquiring AC data on the first shaft (11); the AC data comprising an induced current, an induced voltage, and a phase angle between the induced current and the induced voltage; S3, calculating the insulation impedance of the insulating sealing tile (8) to ground according to the AC data; In S3, the calculation expression of the insulation resistance to ground is: or ;in, is the insulation resistance to ground, is the induced voltage, is the induced current, is the phase angle.

2. The sealing tile insulation impedance testing method according to claim 1, characterized in that: In S1, inputting an alternating magnetic field into the first shaft (11) comprises: inputting an alternating voltage of a preset frequency into a preset induction element (3).

3. The sealing tile insulation impedance testing method according to claim 2, characterized in that: The preset induction component (3) comprises a magnetic conductor (31) and an induction winding arranged on the magnetic conductor (31).

4. A sealing shoe insulation impedance test circuit, used for measuring the insulation impedance of an insulating sealing shoe (8) arranged on a large shaft (1) to ground, characterized in that: The circuit includes: an induction excitation unit (41) connected to the first shaft body (11) of the large shaft (1), and performing an excitation induction process on the first shaft body (11) of the large shaft (1) to make the large shaft (1) enter a predetermined state; the first shaft body (11) is the shaft body of the large shaft (1) close to the first outlet side of the insulating sealing shoe (8) and between the grounding sealing shoe (9); wherein the induction excitation unit (41) comprises an AC power supply for outputting an induced voltage of a preset frequency, a magnetic conductor (31) arranged on the outer periphery of the first shaft body (11), and an induction winding arranged on the trunk of the magnetic conductor (31); the AC power supply is connected to the induction winding; A signal acquisition unit (42) connected to the main shaft (1) and used to collect AC data on the first shaft (11) in the predetermined state; wherein the signal acquisition unit (42) comprises a current acquisition unit (421) for collecting an induced current in the AC data, a voltage acquisition unit (422) for collecting an induced voltage in the AC data, and a phase acquisition unit (423) for measuring a phase angle between the induced current and the induced voltage; the current acquisition unit and the voltage acquisition unit (422) are connected to the first shaft (11), and the phase acquisition unit (423) is connected to the current acquisition unit (421) and the voltage acquisition unit (422); An impedance calculation unit (43) is connected to the signal acquisition unit (42) and is used to calculate the insulation impedance of the insulating sealing tile (8) to the ground according to the AC data; wherein the calculation expression of the insulation impedance to the ground is: or ; is the insulation resistance to ground, is the induced voltage, is the induced current, is the phase.

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