Judgment method of radial magnetic gap of exciter and calculation method of magnetic mid-difference

Abstract

The invention relates to an exciter radial magnetic gap judgment method and a magnetic mid-difference calculation method, and the method comprises the following steps: carrying out the average four-equal-part division of the upper end surfaces of a rotor and a stator according to 90 degrees; a first group of exciter radial magnetic gap distance values; the rotating direction is rotated by 180 degrees; measuring the distance between the corresponding marks of the horizontal axis and the longitudinal axis after rotation again to obtain a second group of exciter radial magnetic gap distance values; when the gap adjustment value in the horizontal direction or the gap adjustment value in the vertical direction is larger than or equal to the average gap value X%, the radial magnetic gap of the exciter needs to be adjusted. According to the method for calculating the magnetic mid-difference of the exciter magnetic force, the magnetic mid-difference of the exciter magnetic force is obtained based on the sum D of the elongation of the shaft of the motor and the shaft of the air blower and the difference a of the offset of the magnetic force center of the exciter, and the problem that no related maintenance technology for the magnetic gap and the magnetic mid-difference of the exciter exists at the present stage is solved.

Description

Technical Field

[0001] The invention belongs to the field of energy and heat, and relates to a method for determining the radial magnetic gap of an exciter and a method for calculating the magnetic mean difference. Background Art

[0002] Ansteel Energy Power Plant Power Plant currently has 8 electric blowers, which are mainly responsible for the blast furnace ironmaking air supply task. Among them, the 8# electric blower was built in 2019. The AV80-15 blower was manufactured by Shaanxi Blower Factory and has a designed maximum air volume of 6530m 3 / min. The variable-frequency motor and exciter are imported from Siemens in Germany. The main operating principle is that the exciter controls the speed of the variable-frequency motor, which in turn drives the axial-flow compressor, which in turn generates air at a certain pressure to supply air to the ironmaking blast furnace. Therefore, electric blowers are key equipment in energy and power plants and are crucial for ensuring stable blast furnace production. In April 2020, during the post-installation commissioning phase of the 8# electric blower, the exciter experienced increased current and voltage, and the excitation coil overheated to 90°C, triggering an alarm and preventing the electric blower from being put into operation. Summary of the Invention

[0003] In order to solve the problem of exciter heating, the present invention adopts a technical solution: a method for determining the radial magnetic gap of an exciter, comprising the following steps:

[0004] Divide the end surface of each side of the rotor and stator into four equal parts at 90°.

[0005] Mark the outer edges of the rotor and stator accordingly;

[0006] Measure the radial magnetic gap between the corresponding marks to obtain the radial magnetic gap distance value X of the first group of exciters 1、 X 2、 Y 1、 Y2;

[0007] Rotate the rotor 180 degrees in the direction of rotation during operation;

[0008] Measure the distance between the corresponding marks on the horizontal and vertical axes after rotation again to obtain the second set of radial magnetic gap distance values X of the exciter. 11、 X 22、 Y 11、 Y 22 ;

[0009] Determine the horizontal clearance adjustment value of the radial magnetic gap of the exciter as follows:

[0010] The adjustment value of the vertical gap of the radial magnetic gap of the exciter is:

[0011] The average gap value Z is:

[0012] When the horizontal gap adjustment value or the vertical gap adjustment value is ≥ the average gap value X%, the radial magnetic gap of the exciter needs to be adjusted.

[0013] Furthermore: the range of X% is 5%-10%.

[0014] According to any one of the methods for adjusting the radial magnetic gap of an exciter, the radial magnetic gap of the exciter is adjusted by horizontally moving the position of the stator or the height of the platform below the stator.

[0015] A method for calculating the magnetic difference of an exciter's magnetic force comprises the following steps:

[0016] Obtain the elongation △L of the variable frequency motor rotor in the working state and the elongation B of the blower rotor at the coupling in the working state; in the non-working state, the distance a1 between the coupling end, the stator coil and the rotor end face; in the non-working state, the distance a2 between the exciter tail end, the stator and the rotor end face;

[0017] The sum of the elongations D of the motor and blower shafts is calculated based on the elongation ΔL of the variable frequency motor rotor in the working state and the elongation B of the blower rotor in the working state at the coupling;

[0018] The magnetic center offset a of the exciter is calculated based on the distance a1 between the coupling end, the stator coil and the rotor end face in the non-working state; and the distance a2 between the exciter tail end, the stator and the rotor end face in the non-working state.

[0019] The magnetic center difference of the exciter magnetic force is obtained based on the difference a between the sum of the elongations D of the motor and blower shafts and the offset of the magnetic center of the exciter.

[0020] Furthermore, the sum of the elongations D of the shafts of the motor and the blower is expressed as follows:

[0021] D=△L / 2+B

[0022] Furthermore: The expression for the magnetic center offset a of the exciter is as follows.

[0023]

[0024] Furthermore, after the radial magnetic gap of the exciter is determined, the position of the stator is adjusted in the axial direction according to the magnetic center difference in the direction opposite to the elongation direction of the motor and the blower shaft.

[0025] The present invention provides a method for judging the radial magnetic gap of an exciter and a method for calculating the magnetic center difference. By analyzing and studying the unique heating fault of the electric blower exciter and combining the actual and existing technologies, a set of magnetic center and magnetic difference measurement and adjustment methods are summarized to solve the problem that there is no relevant maintenance technology for the magnetic gap and magnetic center of the exciter at this stage, explore a new approach in maintenance, fill the maintenance gap in the correlation between electrical and mechanical aspects in actual maintenance work, provide a certain theoretical basis support for the adjustment of magnetic center and magnetic gap, and verify the feasibility of the maintenance technical method through experimental results.

[0026] The method of this application can be used as a basis and expanded to related equipment: such as various large motors, exciters, and generators, which can all use this method for measurement and adjustment to ensure installation accuracy, enable the equipment to operate well, extend the equipment life, and create certain economic value.

[0027] The method of the present application fills a gap in the maintenance of exciters, and also serves as a reference for the maintenance of magnetic centers and magnetic gaps of other types of large motors, generators, and exciters in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0029] Figure 1 This is a simplified structural diagram of the AV80-15 axial flow compressor;

[0030] Figure 2 This is a schematic diagram of the end face when the radial magnetic gap is adjusted and not rotating;

[0031] Figure 3 This is a schematic diagram of the rear end face of the rotation when the radial magnetic gap is adjusted;

[0032] Figure 4 This is a schematic diagram of measuring the offset of the magnetic center line of the magnetic machine;

[0033] Figure 5 Extract the exciter rotor coil gripper. DETAILED DESCRIPTION

[0034] It should be noted that, unless there is any conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] Figure 1 This is a simplified structural diagram of the AV80-15 axial flow compressor; 1#, 2#, 3#, and 4# are support bearings;

[0037] Figure 2 This is a schematic diagram of the end face when the radial magnetic gap is adjusted and not rotating;

[0038] Figure 3 This is a schematic diagram of the rear end face of the rotation when the radial magnetic gap is adjusted;

[0039] A method for determining radial magnetic gap of an exciter comprises the following steps:

[0040] S11: Divide the end surface of each side of the rotor and the stator into four equal parts at 90° angles;

[0041] S12: Mark the outer edges of the rotor and the stator accordingly;

[0042] S13: Measure the distance between the corresponding marks to obtain the radial magnetic gap distance value X of the first group of exciters 1、 X 2、 Y 1、 Y2;

[0043] S14: Rotate the rotor 180 degrees in the direction of rotation during operation;

[0044] S15: Measure the distance between the corresponding marks on the horizontal and vertical axes after rotation again to obtain the second set of radial magnetic gap distance values X of the exciter. 11、 X 22、 Y 11、 Y 22 ;

[0045] S16:

[0046] Determine the horizontal clearance adjustment value of the radial magnetic gap of the exciter as follows:

[0047] The adjustment value of the vertical gap of the radial magnetic gap of the exciter is:

[0048] The average gap value Z is:

[0049] When the horizontal gap adjustment value or the vertical gap adjustment value is ≥ the average gap value X%, the radial magnetic gap of the exciter needs to be adjusted.

[0050] Steps S11, S12, S13, S14, S15, and S16 are performed sequentially;

[0051] The radial magnetic gap of the exciter can be measured with a long wedge-shaped feeler gauge;

[0052] Furthermore, the range of X% is 5%-10%.

[0053] According to any one of the methods for adjusting the radial magnetic gap of an exciter, the adjustment is performed by horizontally moving the position of the stator or the height of the platform below the stator.

[0054] When other conditions change, that is, before the exciter is installed, the radial clearance can also be adjusted by changing the relevant position of the rotor;

[0055] To ensure the electrical performance of the exciter, the magnetic center of the stator of the exciter must be consistent with that of its rotor in the operating state, that is, the stator coil center CC and the rotor center C'C' coincide;

[0056] At present, our company does not have any technical requirements and maintenance methods for the exciter magnetic center. Based on maintenance experience, we can only consider the influence of the thermal expansion of the blower rotor under actual operation, the influence of the axial position determination on the axial position of the variable frequency motor rotor (the variable frequency motor and the exciter rotor are coaxial), and the thermal expansion of the variable frequency motor rotor itself. In the static state, the center CC of the exciter stator and the center C'C' of the rotor must be offset by a value.

[0057] Figure 4 This is a schematic diagram of measuring the offset of the magnetic center line of the magnetic machine;

[0058] A method for calculating the magnetic difference of an exciter's magnetic force comprises the following steps:

[0059] S21: Obtain the elongation ΔL of the variable frequency motor rotor in the working state and the elongation B of the blower in the working state; the distance a1 between the exciter coupling end, the stator coil and the rotor end face in the non-working state; and the distance a2 between the exciter tail end, the stator ends and the rotor hoop in the non-working state;

[0060] S22: Based on the elongation ΔL (mm) of the variable frequency motor rotor in operation and the elongation B (mm) of the blower rotor at the coupling in operation, which values are provided by the manufacturer, calculate the sum of the elongations D (mm) of the motor and blower shafts;

[0061] D = △L / 2 + B;

[0062] The elongation of the variable frequency motor rotor can be calculated as 1 mm per meter of length between the center lines of the two shaft necks;

[0063] S23: In the non-operating state, the magnetic center offset a of the exciter is calculated based on the distance a1 between the coupling end, the stator and the rotor end face, and the distance a2 between the two ends of the stator at the tail end of the exciter and the rotor hoop;

[0064] The magnetic center offset value can be measured with a steel ruler during installation. The expression of the magnetic center offset a of the exciter is as follows:

[0065]

[0066] S24: Based on the difference a between the sum of the elongations D of the shafts of the motor and the blower and the magnetic center offset of the exciter, obtain the magnetic center difference of the exciter magnetic force;

[0067]

[0068] Steps S21 / S22 / S23 / S24 are performed sequentially;

[0069] When the exciter is connected to the generator (motor) with a coupling or the two rotors are coaxial, the generator has a certain elongation after being heated due to its large size, which is represented by △L. Also, after the generator is connected to the blower with a coupling, there is another change in the elongation of the shaft due to thermal expansion, which is represented by B. The two (△L+B) give the exciter rotor an axial force. If the exciter is in the magnetic center position after cold adjustment, after normal operation, the blower and generator shafts will elongate due to heating, causing the axial position of the exciter shaft to change. That is, after normal operation, the magnetic center position is changed, affecting the normal operation of the exciter. Therefore, the magnetic center difference must be calculated in advance, the magnetic center position must be adjusted, and a reserve amount must be reserved for the normal operation of the exciter to ensure that CC and C'C' of the exciter coincide.

[0070] After measuring and adjusting the exciter's magnetic center and gap, and confirming their position, new holes were drilled and reamed on both sides of the exciter stator, and φ8 tapered pins were installed for positioning, facilitating future maintenance work. After retesting, the exciter temperature remained around 55°C, and the unit operated smoothly, ensuring the required air supply to the ironmaking blast furnace.

[0071] A method for measuring, calculating and adjusting the magnetic center offset value of an exciter is disclosed. After the radial magnetic gap of the exciter is determined, the position of the stator is adjusted in the horizontal, vertical and radial directions according to the measured results.

[0072] The adjustment in the axial direction, that is, determining the magnetic center position, is to determine the axial position of the exciter when the exciter is connected to other equipment. The position of the stator is adjusted in the axial direction according to the magnetic center difference in the opposite direction of the elongation direction of the motor and blower shaft to prevent magnetic center deviation from causing the exciter to heat up and burn or reducing the service life of the exciter.

[0073] The premise of adjusting the exciter stator is that the center (coaxiality) of the turbine (blower, steam turbine), generator (motor) and exciter meets the requirements and the coupling is well installed. Adjustment is more difficult, so adjusting the stator is more convenient and more efficient. Before the overall installation of the equipment, the exciter rotor position (moving the motor position) can be adjusted in combination with the movement of the exciter stator position according to actual conditions.

[0074] The exciter of this unit is coaxial with the rotor of the variable frequency motor, and some are connected by a coupling;

[0075] Example 1:

[0076] Analysis of heat generation before decomposition of electric blower: including: 1) whether the temperature measuring element fails;

[0077] 2) Check whether the stator and rotor are scratched and whether the gap is appropriate;

[0078] 3) Check if any control components in the PLC cabinet are faulty;

[0079] 4) Check whether the stator magnets, turns and rotor coils are damaged or falling off;

[0080] 5) Check whether the magnetic position has changed.

[0081] After decomposition, the problem was found:

[0082] 1) Two control switches in the PLC cabinet are not sensitive;

[0083] 2) The rotor coil becomes hot and discolored;

[0084] 3) The horizontal gap between the stator and rotor is 0.60mm on one side and 3-2mm on the other side, resulting in a change in magnetic field and unstable current.

[0085] Processing process:

[0086] 1) Replace the two problematic control switches in the PLC cabinet;

[0087] 2) Disassembly inspection of exciter rotor components;

[0088] 3) Measurement and adjustment of radial magnetic gap of exciter;

[0089] 4) Measurement and adjustment of the exciter magnetic center offset value;

[0090] The exciter rotor coil and other auxiliary components are installed on the tapered shaft at the tail of the motor. Due to rust and excessive tightening force, the coil and auxiliary components are easily damaged by methods such as tearing and knocking. In order to avoid secondary damage, a special top tool is made according to the structural characteristics of the rotor to disassemble the rotor electrical components.

[0091] Figure 5 It is a gripper for extracting the exciter rotor coil

[0092] A gripper for extracting an exciter rotor coil, comprising: a pressure plate flange; the pressure plate flange is made of metal iron;

[0093] Divide the rotor coil flange into 6 equal parts on the same circumference, determine 6 M12 screw holes, make 6 double-headed screws of appropriate length and a steel plate with appropriate outer diameter hole spacing and thickness after measurement, and equip it with a 6-ton screw jack.

[0094] The top-pressing method is used to gradually apply pressure to disassemble the exciter rotor coil and other components. After disassembly, professional testing and processing are carried out to ensure that the exciter rotor meets the use requirements; the production of special top tools improves maintenance efficiency and ensures the integrity of various components on the rotor.

[0095] The rotor of the exciter is coaxial with the variable frequency motor. The exciter rotor coil and other electrical components are fixed to the shaft using the motor tail shaft end. The stator is fixed to the exciter base to ensure that the radial magnetic gap and axial magnetic center between the stator and rotor meet the standards, ensuring stable operation of the exciter, thereby maintaining stable terminal voltage of the motor and improving the static stability of the motor. When a fault occurs inside the variable frequency motor, demagnetization is performed to reduce the degree of fault loss.

[0096] A method for determining radial magnetic gap adjustment of an exciter comprises the following steps:

[0097] S11: Divide the upper end surfaces of the rotor and stator into four equal parts at 90° angles;

[0098] S12: Mark the outer edges of the rotor and the stator accordingly;

[0099] S13: Measure the distances between the corresponding marks to obtain the radial magnetic gap distance values of the first group of exciters: X1 = 0.6 mm, X2 = 3.2 mm, Y1 = 1.95 mm, and Y2 = 1.85 mm;

[0100] S14: Rotate the rotor 180 degrees in the direction of rotation during operation;

[0101] S15: Measure the distance between the corresponding marks on the horizontal and vertical axes after rotation again to obtain the second set of radial magnetic gap distance values X of the exciter. 11 =0.6mm, X 22 =3.2mm, Y 11 =1.95mm, Y 22 =1.85mm;

[0102] Determine the horizontal clearance adjustment value of the radial magnetic gap of the exciter as follows:

[0103] Set X1 = 0.6 mm, X2 = 3.2 mm, X 11 =0.6mm, X 22 =3.2mm into the formula, and the horizontal gap adjustment value is -1.3mm, that is, adjust to the right by 1.3mm;

[0104] The adjustment value of the vertical gap of the radial magnetic gap of the exciter is: Set Y1 = 1.95mm, Y2 = 1.85mm; Y 11 =1.95mm, Y 22 =1.85mm into the formula, and the vertical adjustment value is 0.05mm;

[0105] The average gap value Z is: Substitute X1=0.6mm, X2=3.2mm, Y1=1.95mm, Y2=1.85mm into the formula to obtain Z=1.9mm;

[0106] Average gap value X% = 0.095-0.19mm;

[0107] If the vertical adjustment value is 0.05mm < the average gap value X%, then the radial vertical direction of the exciter does not need to be adjusted;

[0108] Horizontal gap adjustment value: 1.3mm> average gap value X%, then the radial horizontal direction of the exciter needs to be adjusted;

[0109] A method for calculating the magnetic difference of an exciter's magnetic force comprises the following steps:

[0110] S21: Obtain the elongation ΔL of the variable frequency motor rotor in the working state: 3.5 meters, shaft length 3.5*1mm=3.5mm;

[0111] The elongation of the blower in working state is B, 0.5mm;

[0112] In the non-working state, the distance a between the coupling end of the exciter, the stator coil and the rotor end face is 1＝178mm; in the non-working state, the distance a between the tail end of the exciter, the two ends of the stator and the rotor hoop 2＝ 182mm;

[0113] S22: Based on the elongation ΔL (mm) of the variable frequency motor rotor in operation and the elongation B (mm) of the blower rotor at the coupling in operation, which values are provided by the manufacturer, calculate the sum of the elongations D (mm) of the motor and blower shafts;

[0114] D = △L / 2 + B;

[0115] Calculated D is 2.25 mm;

[0116] The elongation of the variable frequency motor rotor can be calculated as 1 mm per meter of length between the center lines of the two shaft necks;

[0117] S23: In the non-operating state, the magnetic center offset a of the exciter is calculated based on the distance a1 between the two ends of the stator and the rotor hoop at the coupling end and the distance a2 between the two ends of the stator and the rotor hoop at the tail end of the exciter;

[0118] The magnetic center offset value can be measured with a steel ruler during installation. The expression of the magnetic center offset a of the exciter is as follows:

[0119]

[0120] a=182-178 / 2=2mm

[0121] S24: Based on the sum of the elongation D of the motor and blower shafts and the difference a between the magnetic center offset of the exciter, the magnetic center difference of the exciter magnetic force is obtained as follows: Magnetic center difference = Da = 2.25-2 = 0.25 mm

[0122] When the calculation result is positive, the stator moves toward the tail end, and when it is negative, the stator moves toward the coupling end;

[0123] Therefore, when the exciter is in static state, the stator axis should be adjusted 0.25mm toward the tail end of a2, so that the stator and rotor of the exciter can coincide during normal operation.

[0124] The exciter's magnetic center and gap were measured and adjusted. Once the position was determined, new holes were drilled and reamed on both sides of the exciter, and φ8 tapered pins were installed for positioning, facilitating future maintenance work. During the retest, the exciter temperature remained around 55°C, and the unit operated smoothly, ensuring the required air supply to the ironmaking blast furnace.

[0125] This method is applied to the measurement and adjustment of magnetic gap and magnetic center of exciters, generators and motors. The scheme can be optimized and selected according to the actual situation of the equipment.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining radial magnetic gap of an exciter, characterized by: The following steps are involved: Divide the end surface of each side of the rotor and stator into four equal parts at 90°. Mark the outer edges of the rotor and stator accordingly; Measure the radial magnetic gap between the corresponding marks to obtain the radial magnetic gap distance value X of the first group of exciters 1、 X 2、 Y 1、 Y2; Rotate the rotor 180 degrees in the direction of rotation during operation; Measure the distance between the corresponding marks on the horizontal and vertical axes after rotation again to obtain the second set of radial magnetic gap distance values X of the exciter. 11、 X 22、 Y 11、 Y 22 ; Determine the horizontal clearance adjustment value of the radial magnetic gap of the exciter as follows: The adjustment value of the vertical gap of the radial magnetic gap of the exciter is: The average gap value Z is: When the horizontal gap adjustment value or the vertical gap adjustment value is greater than or equal to the average gap value X%, and the X% range is 5%-10%, the radial magnetic gap of the exciter needs to be adjusted.

2. The adjustment method for determining the radial magnetic gap of an exciter according to any one of claim 1, characterized in that: The radial magnetic gap of the exciter is adjusted by moving the position of the stator or the height of the platform below the stator in the horizontal direction.

3. A method for calculating the magnetic difference of an exciter's magnetic force, characterized by: The following steps are involved: Obtain the elongation △L of the variable frequency motor rotor in the working state and the elongation B of the blower rotor at the coupling in the working state; in the non-working state, the distance a1 between the coupling end, the stator coil and the rotor end face; in the non-working state, the distance a2 between the exciter tail end, the stator and the rotor end face; The sum of the elongations D of the motor and blower shafts is calculated based on the elongation ΔL of the variable frequency motor rotor in the working state and the elongation B of the blower rotor in the working state at the coupling; The magnetic center offset a of the exciter is calculated based on the distance a1 between the coupling end, the stator coil and the rotor end face in the non-working state; and the distance a2 between the exciter tail end, the stator and the rotor end face in the non-working state. The magnetic center difference of the exciter magnetic force is obtained based on the difference a between the sum of the elongations D of the motor and blower shafts and the offset of the magnetic center of the exciter.

4. The method for adjusting the calculation method of the exciter magnetic center offset value according to claim 3, characterized in that: The expression for the sum of the elongation D of the motor and blower shafts is as follows. D=△L / 2+B 5. The method for adjusting the calculation method of the exciter magnetic center offset value according to claim 3, characterized in that: The expression for the magnetic center offset a of the exciter is as follows.

6. The method for adjusting the calculation method of the exciter magnetic center offset value according to claims 3-5, characterized in that: When the radial magnetic gap of the exciter is determined, the position of the stator is adjusted in the axial direction according to the magnetic center difference in the opposite direction to the extension direction of the motor and blower shaft.

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