Torsional vibration suppression system and method for synchronous motor

Abstract

The present invention relates to the technical field of high-power synchronous motors, and more particularly to a torsional vibration suppression system and method for synchronous motors. The torsional vibration suppression system includes a detection device and a suppression device; the suppression device includes a data acquisition unit, a calculation and analysis unit, and an execution unit, all of which are communicatively connected. The detection device is used to monitor torsional vibration parameters in real time and transmit the torsional vibration parameters to the data acquisition unit; the calculation and analysis unit is used to calculate the excitation current waveform required for torsional vibration suppression based on the collected torsional vibration parameters; and the execution unit generates the required excitation current waveform based on the calculation results of the calculation and analysis unit and outputs the waveform, which is superimposed on the excitation current output by the exciter and then transmitted to the synchronous motor rotor. This suppression system and method effectively solves the problem that existing suppression methods cannot be used for synchronous motors, and the system is a separate execution device.

Description

Technical Field

[0001] The present invention relates to the technical field of high-power synchronous motors, and in particular to a torsional vibration suppression system and method for synchronous motors. Background Art

[0002] Torsional vibration, also known as torsional vibration, occurs when the prime mover in a rotating mechanical system transmits power to the load through the shaft system, resulting in unequal torsional angles between the shaft segments. The vibrations generated by the back-and-forth twisting of the shaft segments are called torsional vibration. Shaft damage caused by torsional vibration can include cracks or fractures at the blade roots, cracks or fractures in the drive shaft, damage or fractures in the coupling, and cracks or fractures in the motor shaft. These damages can affect the safe and reliable operation of the unit and, in severe cases, can even cause serious accidents resulting in loss of life and damage to the unit.

[0003] Several existing technical solutions exist for suppressing torsional vibration in wind turbines, such as the Chinese invention patent publication number CN104196678A, published on December 10, 2014. This patent discloses a method for suppressing torsional vibration in a wind turbine transmission system. This method monitors the torsional vibration amplitude of the transmission system by measuring the rotational speed at different connection points. Torque fluctuations are suppressed by adjusting the electromagnetic torque of the generator, thereby suppressing torsional vibration and reducing torsional fatigue loads in the transmission system.

[0004] However, the above technical solution is only applicable to wind power generation and is not applicable to torsional vibration suppression of other large motors. In the above solution, the actuator for suppressing torsional vibration is the converter, and torsional vibration suppression is achieved by changing the algorithm of the converter main control program. However, the drive system of a large synchronous motor may not have an converter. Even for a large synchronous motor driven by a converter, a large part of its torsional vibration comes from the converter itself. Converter manufacturers, especially imported converter manufacturers, are unlikely to open their main control systems for others to modify at will. Therefore, the above technical solution cannot be applied to torsional vibration suppression of large synchronous motors. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a torsional vibration suppression system and method for synchronous motors. Starting from another suppression idea, it effectively solves the problem that existing suppression methods cannot be used for synchronous motors, and the system is a separate execution device.

[0006] The present invention is achieved by adopting the following technical solutions:

[0007] A torsional vibration suppression system for a synchronous motor, characterized in that it includes a detection device and a suppression device; the suppression device includes a data acquisition unit, a calculation and analysis unit, and an execution unit that are communicatively connected; the detection device is used to monitor torsional vibration parameters in real time and send the torsional vibration parameters to the data acquisition unit; the calculation and analysis unit is used to calculate the excitation current waveform required for suppressing torsional vibration based on the collected torsional vibration parameters; the execution unit generates the required excitation current waveform based on the calculation result of the calculation and analysis unit, and outputs the waveform, which is superimposed on the excitation current output by the exciter and then sent to the rotor of the synchronous motor.

[0008] The torsional vibration parameters include frequency, intensity and phase angle.

[0009] A method for suppressing torsional vibration of a synchronous motor, characterized by comprising the following steps:

[0010] S1. Data acquisition, including torsional vibration parameters;

[0011] S2. Calculate the excitation current waveform required to suppress torsional vibration in real time based on the collected torsional vibration parameters;

[0012] S3. Generates the excitation current waveform required to suppress torsional vibration, superimposes the excitation current waveform on the excitation current output by the exciter, and then transmits it to the synchronous motor rotor.

[0013] Wherein, the step S2 specifically includes:

[0014] S 21 Let T = T static +T vib ,

[0015] Among them, T is the actual torque of the motor, T static is the target torque, T vib It is the torque fluctuation or vibration generated on the shaft system;

[0016] S 22 . To T vib Perform Fourier series decomposition to obtain a set of harmonics:

[0017] T vib =

[0018] Where ω is the fundamental frequency, is the amplitude of each harmonic, is the phase angle of each harmonic;

[0019] S 23 . Select the first three harmonics with the largest amplitude, i.e. the order k = r 、 p 、q , calculate the corresponding torque component T r 、T p 、T q ;

[0020] S 24 . Establish and step S respectively 23 Harmonic torque T of the middle harmonic reverse r1 、T p1 、T q1 ;

[0021] S 25 . Calculate the excitation current waveform required to suppress torsional vibration:

[0022] I fvib = + ,

[0023] in:

[0024] ,

[0025] ,

[0026] ,

[0027] in, C and Represent the motor constant and the sine value of the power angle respectively, r is the harmonic order with the highest amplitude, p 、 q are the harmonic orders with the second highest amplitude, B r 、 B p and B q are the amplitudes of the corresponding sub-reverse harmonic torques, θ r 、 θ p and θ q are the phase angles of the corresponding subharmonics.

[0028] The step S 23 The torque component T r 、T p 、T q The calculation method is:

[0029] T r = ,

[0030] T p = ,

[0031] T q = ,

[0032] The step S 24 Harmonic torque T in the opposite direction to the harmonic r1 、T p1 、T q1 The calculation method is:

[0033] T r1 = ,

[0034] T p1 = ,

[0035] T q1 = ,

[0036] in, r is the harmonic order with the highest amplitude, p 、 q are the harmonic orders with the second highest amplitude, A r 、 A p and A q are the amplitudes of the corresponding subharmonic torques, θ r 、 θ p and θ q are the phase angles of the corresponding subharmonics.

[0037] The step S 23 middle, k The value is less than 20.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. When torsional vibration occurs, the torque of the synchronous motor rotor will fluctuate. Through this suppression system and suppression method, by controlling the magnitude of the rotor excitation current, the excitation current of the synchronous motor rotor is changed, thereby generating a torque fluctuation on the synchronous motor rotor that is consistent with the frequency and intensity of the shaft system torsional vibration and opposite in phase, thereby smoothing the torque fluctuation caused by the torsional vibration, thereby achieving the purpose of suppressing the torsional vibration.

[0040] The present suppression system and suppression method can effectively suppress the torsional vibration of large synchronous motors during operation, ensuring the safe operation of the system. Although large rotating mechanical equipment uses various means to avoid the generation of torsional vibration as much as possible during the design phase, the actual situation is that due to the limitations of the understanding of shaft system operation, the complexity of the operating environment, and the differences in the manufacturing process, the generation of torsional vibration cannot be completely avoided. Torsional vibration has a very destructive effect on large rotating mechanical equipment and can cause serious accidents. The advantage of the present invention is that it does not require any changes to the original mechanical equipment, and solves this problem through advanced power electronics technology. The project implementation is simple, and the effect of suppressing torsional vibration is significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, wherein:

[0042] Figure 1 Schematic diagram of the connection of the torsional vibration suppression system of the present invention;

[0043] Figure 2 Schematic diagram of the structure of the suppression device in the present invention;

[0044] Figure 3 Schematic diagram of the speed waveform before torsional vibration suppression in the present invention;

[0045] Figure 4 Schematic diagram of the waveform output by the torsional vibration suppression system of the present invention;

[0046] Figure 5 Schematic diagram of the speed waveform after torsional vibration suppression in the present invention;

[0047] Figure 6 This is a schematic diagram of the present invention before torsional vibration suppression during the experiment;

[0048] Figure 7 This is a schematic diagram of the present invention after torsional vibration suppression during the experiment;

[0049] Markings in the figure:

[0050] 1. Detection device, 2. Suppression device, 3. Exciter, 4. Synchronous motor, 5. Data acquisition unit, 6. Calculation and analysis unit, 7. Execution unit. DETAILED DESCRIPTION

[0051] Example 1

[0052] As a basic embodiment of the present invention, a torsional vibration suppression system for a large synchronous motor comprises a detection device 1 and a suppression device 2. The large synchronous motor 4 has a power greater than 8 MW. The suppression device 2 comprises a data acquisition unit 5, a calculation and analysis unit 6, and an execution unit 7, all of which are communicatively connected. The detection device 1, which can be the TJ-400 device for real-time torsional vibration monitoring developed by Deyang Ruineng Electric Power Technology Co., Ltd., provides the suppression device 2 with torsional vibration parameters, including the torsional angle and frequency of the shaft torsional vibration. The detection device 1 can transmit the detected torsional vibration parameters to the data acquisition unit 5 via communication. The calculation and analysis unit 6 is configured to calculate the excitation current waveform required for torsional vibration suppression based on the collected torsional vibration parameters. The execution unit 7 generates the required excitation current waveform based on the calculation results of the calculation and analysis unit 6 and outputs it, superimposed on the excitation current output by the exciter 3, before transmitting it to the rotor of the synchronous motor 4. A magnetic field with a frequency consistent with the shaft torsional vibration and a phase opposite thereto is established on the rotor of the synchronous motor 4 to suppress torsional vibration, thereby achieving the torsional vibration suppression function.

[0053] Example 2

[0054] As a preferred embodiment of the present invention, the present invention includes a method for suppressing torsional vibration of a synchronous motor, comprising the following steps:

[0055] S1. Data acquisition, including the acquisition of torsional vibration parameters.

[0056] S2. Based on the collected torsional vibration parameters, calculate and analyze the excitation current waveform required to suppress torsional vibration in real time. This specifically includes the following steps:

[0057] S 21 Let T = T static +T vib ,

[0058] Among them, T is the actual torque of the motor, T static is the target torque, T vib It is the torque fluctuation or vibration generated on the shaft system;

[0059] S 22 . To T vib Perform Fourier series decomposition to obtain a set of harmonics:

[0060] T vib =

[0061] Where ω is the fundamental frequency, is the amplitude of each harmonic, is the phase angle of each harmonic;

[0062] S 23. Select the first three harmonics with the largest amplitude, i.e. the order k = r 、 p 、 q , calculate the corresponding torque component T r 、T p 、T q ;

[0063] S 24 . Establish and step S respectively 23 Harmonic torque T of the middle harmonic reverse r1 、T p1 、T q1 ;

[0064] S 25 . Calculate the excitation current waveform required to suppress torsional vibration:

[0065] I fvib = + ;

[0066] ,

[0067] ,

[0068] .

[0069] in, C and Represent the motor constant and the sine value of the power angle respectively, r is the harmonic order with the highest amplitude, p 、 q are the harmonic orders with the second highest amplitude, B r 、 B p and B q are the amplitudes of the corresponding sub-reverse harmonic torques, θ r 、 θ p and θ q are the phase angles of the corresponding subharmonics.

[0070] S3. Generate an excitation current waveform required to suppress torsional vibration, superimpose the excitation current waveform on the excitation current output by the exciter 3, and then send it to the rotor of the synchronous motor 4.

[0071] Example 3

[0072] As the best embodiment of the present invention, refer to the attached Figure 1 and instructions attached Figure 2The present invention comprises a torsional vibration suppression system for a synchronous motor, in particular for a large synchronous motor 4 with a power greater than 8 MW.

[0073] The torsional vibration suppression system includes a detection device 1 and a suppression device 2. The suppression device 2 includes a data acquisition unit 5, a calculation and analysis unit 6, and an execution unit 7 that are communicatively connected. The detection device 1 is a real-time monitoring device for torsional vibration, which can monitor the torsional vibration parameters of the shaft system in real time, including the intensity, phase angle, and frequency of the torsional vibration, and send the torsional vibration parameters to the data acquisition unit 5 in a communication manner. The calculation and analysis unit 6 calculates the excitation current waveform required to suppress torsional vibration based on the collected torsional vibration parameters. The execution unit 7 generates the required excitation current waveform based on the calculation result of the calculation and analysis unit 6 and outputs it superimposed on the excitation current output by the exciter 4 and then sends it to the rotor of the synchronous motor 4. A magnetic field with a frequency consistent with the torsional vibration of the shaft system and an opposite phase is established on the rotor of the synchronous motor 4 to suppress torsional vibration, thereby realizing the function of torsional vibration suppression.

[0074] A method for suppressing torsional vibration of a synchronous motor using the above-mentioned torsional vibration system comprises the following steps:

[0075] S1. Data acquisition, including torsional vibration parameter acquisition.

[0076] S2. Calculate the excitation current waveform required to suppress torsional vibration in real time based on the collected torsional vibration parameters. This includes the following steps:

[0077] S 21 Let T = T static +T vib ,

[0078] Wherein, T is the actual torque of the motor; T static is the target torque, constant; T vib It is the torque fluctuation or vibration generated on the shaft system.

[0079] S 22 . To T vib Perform Fourier series decomposition to obtain a set of harmonics:

[0080] T vib =

[0081] Where ω is the fundamental frequency, which is measured based on the current rotation frequency; is the amplitude of each harmonic, is the phase angle of each harmonic.

[0082] S 23 . According to experience, select k The value is less than 20, sort the harmonics by amplitude and select the first three harmonics with the largest amplitude, that is, the orderk = r 、 p 、 q , calculate the corresponding torque component T r 、T p 、T q ;

[0083] T r =

[0084] Where, r is the harmonic order with the highest amplitude, A r is the amplitude of this harmonic torque, θ r is the phase angle of this harmonic.

[0085] T p =

[0086] Where, p is the harmonic order with the second highest amplitude, A p is the amplitude of this harmonic torque, θ p is the phase angle of this harmonic.

[0087] T q =

[0088] Where, q is the harmonic order with the second highest amplitude, A q is the amplitude of this harmonic torque, θ q is the phase angle of this harmonic.

[0089] S 24 As the tracking object, establish the harmonic torque in the opposite direction to achieve the torque suppression effect, that is, establish the same as step S 23 Harmonic torque T of the middle harmonic reverse r1 、T p1 、T q1 :

[0090] T r1 = ,

[0091] T p1 = ,

[0092] T q1 = .

[0093] S 25Calculate the excitation current waveform required to suppress torsional vibration. Under the given conditions of input current and power angle, the reverse harmonic torque is regulated by the synchronous motor excitation current:

[0094] T=C×If× ,

[0095] Where: T is the electromagnetic torque of the motor, C and They represent the motor constant and the sine value of the power angle respectively, both of which are constants.

[0096] Therefore, we only need to order:

[0097] I fvib = + ;

[0098] in,

[0099] ,

[0100] ,

[0101] .

[0102] S3. Generate an excitation current waveform required for suppressing torsional vibration, superimpose the excitation current waveform on the excitation current output by the exciter 4, and then send it to the rotor of the synchronous motor 4.

[0103] When torsional vibration occurs in a rotating machinery shaft, the detection device 1 performs online torsional vibration monitoring, detecting the shaft torsion angle and frequency. By analyzing the motor current, it is found that the torque current also fluctuates at a corresponding frequency. The torque current of the synchronous motor 4 is related to the magnitude of the rotor excitation current.

[0104] A system-level torsional vibration simulation model was established. Through simulation, it was found that when the shaft system is in the step excitation driving state, step excitation is more likely to excite torsional vibration than when it is in the power frequency driving state. Furthermore, the above system and method were used to simulate the suppression effect of torsional vibration. The simulation results are shown in the attached manual. Figures 3-5 As shown in the figure, from the speed waveform when the torsional vibration suppression system is not working, obvious speed oscillation can be seen, and from the speed waveform after the torsional vibration suppression system is involved, it can be seen that the speed waveform is very smooth.

[0105] Furthermore, a small experimental system is established to simulate the torsional vibration phenomenon, and the accuracy of the mathematical model of torsional vibration is verified by changing the parameters. At the same time, the torsional vibration suppression algorithm can also be studied and verified. It is found through experiments that when torsional vibration occurs, the torque of the synchronous motor 4 fluctuates. Through this system and method, by controlling the magnitude of the rotor excitation current, this torque fluctuation is offset, and the purpose of suppressing torsional vibration can be achieved. For specific experimental results, please refer to the attached manual. Figure 6and instructions attached Figure 7 .

[0106] In summary, after reading the present invention document, ordinary technicians in this field can make various other corresponding transformation schemes based on the technical solutions and technical concepts of the present invention without creative mental work, which all fall within the scope of protection of the present invention.

Claims

1. A method for suppressing torsional vibration of a synchronous motor, characterized in that: The following steps are involved: S1. Data acquisition, including torsional vibration parameters; S2. Calculate the excitation current waveform required to suppress torsional vibration in real time based on the collected torsional vibration parameters; include: S 21 Let T = T static +T vib , Among them, T is the actual torque of the motor, T static is the target torque, T vib It is the torque fluctuation or vibration generated on the shaft system; S 22 . To T vib Perform Fourier series decomposition to obtain a set of harmonics: T vib = ， Where ω is the fundamental frequency, is the amplitude of each harmonic, is the phase angle of each harmonic; S 23 . Select the first three harmonics with the largest amplitude, i.e. the order k = r 、 p 、 q , calculate the corresponding torque component T r 、T p 、T q ; S 24 . Establish and step S respectively 23 Harmonic torque T of the middle harmonic reverse r1 、T p1 、T q1 ; S 25 . Calculate the excitation current waveform required to suppress torsional vibration: I fvib = + ； ， ， ， in, C and Represent the motor constant and the sine value of the power angle respectively, r is the harmonic order with the highest amplitude, p 、 q are the harmonic orders with the second highest amplitude, B r 、 B p and B q are the amplitudes of the corresponding sub-reverse harmonic torques, θ r 、 θ p and θ q are the phase angles of the corresponding subharmonics; S3. Generates the excitation current waveform required to suppress torsional vibration and superimposes the excitation current waveform on the excitation current output by the exciter (3) and then sends it to the rotor of the synchronous motor (4).

2. The method for suppressing torsional vibration of a synchronous motor according to claim 1, wherein: Step S 23 The torque component T r 、T p 、T q The calculation method is: T r = ， T p = ， T q = ， Step S 24 Harmonic torque T in the opposite direction to the harmonic r1 、T p1 、T q1 The calculation method is: T r1 = ， T p1 = ， T q1 = ， in, r is the harmonic order with the highest amplitude, p 、 q are the harmonic orders with the second highest amplitude, A r 、 A p and A q are the amplitudes of the corresponding subharmonic torques, θ r 、 θ p and θ q are the phase angles of the corresponding subharmonics.

3. A method for suppressing torsional vibration of a synchronous motor according to claim 1 or 2, characterized in that: Step S 23 middle, k The value is less than 20.

4. A torsional vibration suppression system for a synchronous motor, characterized in that: The invention is constructed based on the torsional vibration suppression method according to claim 1; the system comprises a detection device (1) and a suppression device (2); the suppression device (2) comprises a data acquisition unit (5), a calculation and analysis unit (6) and an execution unit (7) which are communicatively connected; the detection device (1) is used to monitor the torsional vibration parameters in real time and send the torsional vibration parameters to the data acquisition unit (5); the calculation and analysis unit (6) is used to calculate the excitation current waveform required for suppressing torsional vibration based on the collected torsional vibration parameters; the execution unit (7) generates the required excitation current waveform based on the calculation result of the calculation and analysis unit (6) and outputs the waveform to be superimposed on the excitation current output by the exciter (3) and then sends it to the rotor of the synchronous motor (4).

5. The torsional vibration suppression system for a synchronous motor according to claim 4, characterized in that: The torsional vibration parameters include frequency, intensity and phase angle.

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