Transient parameter identification method and system for large-capacity ac excitation motor for variable speed pumping storage

Abstract

The present application belongs to the technical field of motor parameter identification, and discloses a transient parameter identification method and system for a large-capacity AC excitation motor for variable speed pumping storage, which comprises: based on the operation circuit of the large-capacity AC excitation motor for variable speed pumping storage, a first frequency domain expression of the d-axis current of the stator and rotor under the excitation of a first excitation source is established; the d-axis current waveform of the stator and rotor under the excitation of the first excitation source is obtained, the time domain fitting of the d-axis current waveform of the stator and rotor is carried out by using the time domain general solution form, and the expression after the time domain fitting is converted into a frequency domain form to serve as a second frequency domain expression of the d-axis current of the stator and rotor; and the motor transient parameters to be identified are obtained based on the two frequency domain expressions. The parameter identification method has the advantages of low requirement for equipment, higher safety, simpler operation, and can directly identify all parameters of the large-capacity AC excitation motor, compared with the traditional parameter identification test, the parameter change characteristics caused by magnetic field saturation can be considered, and the identification accuracy is higher.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of motor parameter identification, and more particularly relates to a transient parameter identification method and system for a large-capacity variable-speed pumped storage AC excitation motor. BACKGROUND

[0002] One of the main features of the new power system is the wide access of high proportion of renewable energy. The proportion of renewable energy power mainly from wind and light has greatly increased. However, the random fluctuation of new energy brings great challenges to the safety and stability of the new power system. In order to cope with the challenges brought by the random fluctuation of new energy, large-scale energy storage technology is developed to solve the problem of new energy grid-connection. Among them, pumped storage is the most economical, mature and large-scale development condition of energy storage technology.

[0003] The equivalent circuit parameters of the large-capacity variable-speed pumped storage AC excitation motor directly affect the power regulation range and response speed of the motor to the power grid. Therefore, the new power system has higher requirements for the accuracy of the design of the parameters of the large-capacity variable-speed pumped storage AC excitation motor. After the motor is manufactured, the parameters of the motor need to be measured to verify the accuracy of the parameter design. The most well-known parameter measurement method for double-fed motors at the present stage is the no-load and locked-rotor test mentioned in the IEEE standard. However, the no-load and locked-rotor test for the large-capacity variable-speed pumped storage AC excitation motor requires a high voltage level of the voltage regulator, and a large current is passed during the test process. There are problems such as high requirements for equipment, high difficulty of test, low safety, and difficulty in accurately calculating the stator and rotor leakage reactance parameters (the stator and rotor leakage reactances are assumed to be equal in the no-load and locked-rotor test, but in actual working conditions, the two are not equal). Therefore, it is difficult to apply the method to the parameter measurement of the large-capacity variable-speed pumped storage AC excitation motor. If a parameter measurement method with high safety, low test difficulty and low requirement for equipment can be proposed for the large-capacity variable-speed pumped storage AC excitation motor to guide the electromagnetic design of the large-capacity variable-speed pumped storage AC excitation motor, it will be beneficial to fully play the supporting role of the large-capacity variable-speed pumped storage AC excitation motor to the new power system. SUMMARY

[0004] In view of the above defects or improvement needs of the prior art, the application provides a transient parameter identification method and system for a large-capacity variable-speed pumped storage AC excitation motor, which aims to provide a parameter identification method with high safety, low test difficulty and low requirement for equipment for the large-capacity variable-speed pumped storage AC excitation motor, and improve the accuracy of parameter identification.

[0005] To achieve the above-mentioned purpose, according to the first aspect of the application, a transient parameter identification method for a large-capacity variable-speed pumped storage AC excitation motor is provided, comprising:

[0006] The first frequency domain expression of the stator and rotor d-axis currents is established based on the operation circuit of the large-capacity AC excitation motor for variable speed pumping storage under the excitation of the first excitation source, wherein the frequency domain expression contains to-be-identified motor transient parameters;

[0007] Under the excitation of the first excitation source, the three-phase current waveforms of the stator and rotor of the large-capacity AC excitation motor for variable speed pumping storage are recorded to obtain the corresponding d-axis current waveforms of the stator and rotor.

[0008] The first frequency domain expression of the stator and rotor d-axis currents is converted into a time domain form to obtain a time domain general solution form of the d-axis current of the stator and rotor; the corresponding d-axis current waveforms of the stator and rotor are fitted in the time domain by using the time domain general solution form, and the expression after the time domain fitting is converted into a frequency domain form to serve as a second frequency domain expression of the corresponding d-axis current of the stator and rotor.

[0009] The to-be-identified motor transient parameters contained in the first frequency domain expression are solved based on the principle that the coefficients in the second frequency domain expression are equal to the coefficients in the first frequency domain expression.

[0010] Further, the first frequency domain expression of the d-axis current of the stator and rotor is established based on the operation circuit of the large-capacity AC excitation motor for variable speed pumping storage under the excitation of the first excitation source, including:

[0011] Under the experimental conditions that the stator winding of the large-capacity AC excitation motor for variable speed pumping storage is excited by the excitation voltage of the first excitation source, the rotor is zero excitation, and the rotor is static, a stator d-axis voltage equation is obtained.

[0012] The first frequency domain expression of the d-axis current of the stator and rotor is obtained by combining the stator d-axis voltage equation with the operation circuit of the large-capacity AC excitation motor for variable speed pumping storage.

[0013] Further, when the excitation voltage of the first excitation source is a direct current step voltage, the first frequency domain expression is:

[0014]

[0015] In the formula, I ds (p), I dr (p) are respectively the first frequency domain expressions of the d-axis current of the stator and rotor, p represents an operation operator; U ds is the stator d-axis voltage; L ss is the steady-state inductance of the stator, L ss ′ is the transient inductance of the stator, L m is the mutual inductance between the windings of the stator and rotor in the dq coordinate system, T r is the time constant of the rotor winding, T r′ is the transient time constant of the rotor winding, r s r is the resistance of the stator winding. r L is the resistance of the rotor winding; where L ss L ss ′、L m T r and T r ′ are all parameters to be identified.

[0016] Furthermore, the time-domain general solution of the stator and rotor d-axis currents is as follows:

[0017]

[0018] In the formula, I ds (t) represents the stator d-axis current at time t, I dr (t) represents the rotor d-axis current at time t; A s B s A r B r Let λ1 and λ2 be the amplitude coefficients of each exponential function, and I be the decay coefficients of the exponential function. ds∞ Let A be the steady-state value of the stator d-axis current; where A s B s A r B r ,λ1,λ2,I ds∞ It is an unknown variable;

[0019] The time-domain general solution is used to fit the corresponding stator and rotor d-axis current waveforms in the time domain, resulting in the time-domain fitted expressions, including:

[0020] The following optimization objective function is established:

[0021]

[0022] Where J1 represents the difference between the sampled value and the fitted value of the stator d-axis current, and J2 represents the difference between the sampled value and the fitted value of the rotor d-axis current; I ds (t i ) and I ds ain (t i ) respectively represent fixed

[0023] Sub-d-axis current at t i Sampled values ​​and fitted values ​​at time points; I dr (t i ) and I dr ain (t i ) represent the rotor d-axis respectively

[0024] Current at ti The sampling value and the fitting value at the moment; N1 and N2 are respectively the number of points for sampling the stator and rotor d-axis currents;

[0025] The optimal A s , B s , A r , B r , λ1, λ2 and I ds∞ are obtained by solving the objective function by using an optimization algorithm, and the expression after time-domain fitting is obtained.

[0026] Further, the relationship between the coefficients in the second frequency-domain expression and the to-be-identified motor transient parameters contained in the first frequency-domain expression is as follows:

[0027]

[0028] In the formula, α0, α1, β0, γ1, γ2 and γ3 are coefficients in the second frequency-domain expression, wherein the second frequency-domain expression is obtained by performing Laplace transformation on the expression after time-domain fitting; L ss , L ss ', L m , T r and T r are the to-be-identified parameters.

[0029] Further, the to-be-identified parameters further include any one or more of the stator leakage inductance L sl , the rotor self-inductance L rr , the transient inductance L' rr of the rotor winding when the stator winding is short-circuited and the rotor leakage inductance L rl ;

[0030] L sl , L rr , L' rr are determined by the following formula:

[0031]

[0032] Further, the method further includes correcting the identified parameters, and specifically includes:

[0033] The physical model of the large-capacity AC excitation motor for variable-speed pumped storage is established by using finite element software;

[0034] The current stator and rotor tooth magnetic motive force, air gap magnetic motive force and yoke magnetic motive force are obtained under the excitation of the first excitation source, so as to calculate the first saturation coefficient K s1 ;

[0035] The physical model obtains the current stator-tooth magnetic motive force, air-gap magnetic motive force and yoke magnetic motive force under the excitation of the second excitation source, to calculate the second saturation coefficient K s2 at this time

[0036] Based on the first saturation coefficient K s1 and the second saturation coefficient K s2 , the motor reactance parameter L1 is corrected to obtain the corrected motor reactance parameter L2; wherein the correction formula is:

[0037]

[0038] In the formula, L1 takes L ss , L ss ', L m , L sl , L rr , L' rr or L rl in turn, and L2 corresponds to the corrected L ss , L ss ', L m , L sl , L rr , L' rr or L rl ;

[0039] Based on the formula , the corrected rotor winding time constant T r and the rotor winding transient time constant T r ' are obtained.

[0040] Further, under the excitation of the first excitation source, the three-phase current waveforms of the stator and rotor of the variable-speed pumped storage large-capacity AC excitation motor are recorded to correspondingly obtain the d-axis current waveforms of the stator and rotor, including:

[0041] The three-phase winding axes of the stator and rotor of the variable-speed pumped storage large-capacity AC excitation motor are aligned to obtain the included angle of the three-phase winding axes; wherein the three-phase winding axes of the stator and rotor of the variable-speed pumped storage large-capacity AC excitation motor are aligned, including: opening the rotor winding, applying an alternating voltage of a rated frequency to the stator windings A and B, rotating the rotor, and measuring the rotor U and V phase line voltages using an oscilloscope; when the maximum value of the rotor U and V phase line voltage waveform amplitude appears, stop rotating the rotor, at which time the stator and rotor three-phase winding axes are aligned;

[0042] After the stator and rotor three-phase winding axes are aligned, the rotor winding is short-circuited, the excitation voltage of the first excitation source is applied to the stator A and B phases, and the stator A phase current and the rotor U phase current are recorded using an oscilloscope;

[0043] Based on the included angle of the three-phase winding axis, the stator A-phase current and the rotor U-phase current are converted from the abc three-phase coordinate system to the dq coordinate system to obtain the d-axis current waveform of the stator and the rotor.

[0044] According to the second aspect of the present application, a variable-speed pumped storage large-capacity AC excitation motor transient parameter identification system is provided, comprising a computer readable storage medium and a processor.

[0045] The computer readable storage medium is used to store executable instructions.

[0046] The processor is used to read the executable instructions stored in the computer readable storage medium to execute the variable-speed pumped storage large-capacity AC excitation motor transient parameter identification method of any one of the first aspect.

[0047] According to the third aspect of the present application, a computer readable storage medium is provided, which stores a computer program, and the program is executed by a processor to realize the variable-speed pumped storage large-capacity AC excitation motor transient parameter identification method of any one of the first aspect.

[0048] Overall, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0049] (1) The application first establishes the frequency domain expression of the stator and rotor d-axis current under the excitation of the first excitation source (taking it as the first frequency domain expression) through the operation circuit (mathematical model) of the large-capacity AC excitation motor to be measured; then obtains the stator and rotor d-axis current waveform of the large-capacity AC excitation motor to be measured under the excitation of the same excitation source, and performs time domain fitting on the stator and rotor d-axis current waveform. In the fitting process, the time domain general solution form of the stator and rotor d-axis current waveform in the time domain fitting can be obtained based on the frequency domain expression of the stator and rotor d-axis current obtained by the operation circuit, and based on the time domain general solution form and the known stator and rotor d-axis current waveform, the stator and rotor d-axis current waveform expression after time domain fitting can be obtained. After converting the stator and rotor d-axis current waveform expression after time domain fitting into the frequency domain, the obtained stator and rotor d-axis current waveform frequency domain expression is taken as the second frequency domain expression. By comparing the coefficients of the first frequency domain expression and the second frequency domain expression, the equivalent circuit parameters of the large-capacity AC excitation motor, i.e. the motor transient parameters to be identified, can be obtained. Compared with the traditional no-load locked-rotor parameter determination test, the application provides a new parameter identification method for the large-capacity AC excitation motor for variable speed pumping storage. The parameters in the equivalent circuit are identified by the stator and rotor d-axis current frequency domain expression obtained in the experiment. The first excitation source used in the experiment only needs to obtain the stator and rotor three-phase current waveform of the large-capacity AC excitation motor for variable speed pumping storage, without the need to pass a large current or voltage, and without the need for special protection devices. The application has low requirements for experimental equipment, is safer and easier to operate, and has high identification accuracy in the identification process without assuming that the stator and rotor leakage reactances are equal, which is consistent with the actual working condition.

[0050] (2) As a preferred embodiment, the excitation voltage of the first excitation source is a direct current step voltage, which can greatly reduce the complexity of calculation and facilitate the derivation and solution of the corresponding first frequency domain expression and second frequency domain expression.

[0051] (3) As a preferred embodiment, in the time domain fitting, the time domain fitting problem is converted into a multi-parameter two-target optimization problem, the difference between the sampling value and the fitting value of the stator and rotor d-axis current is taken as the optimization target, and an optimization algorithm is used to solve A s , B s , A r , B r , λ1, λ2, I ds∞ , so as to obtain the expression after time domain fitting.

[0052] (4) Further, the identification method of the application can identify the steady-state inductance L ss of the stator, the transient inductance L ss ' of the stator, the mutual inductance L m between the windings in the dq coordinate system, the stator leakage inductance L sl , and the rotor self-inductance L rr, the transient inductance L' of the rotor winding when the stator winding is short-circuited rr , and the rotor leakage inductance L rl In addition to the motor reactance parameters, the rotor winding time constant T r and the transient time constant T r of the rotor winding are identified, all parameters of the large-capacity AC excitation motor are identified, the actual stator and rotor leakage inductances are identified without assuming that the stator and rotor leakage inductances are equal, and the identification accuracy is higher.

[0053] (5) Further, considering that the permeability of the large-capacity AC excitation motor for variable-speed pumped storage under actual working conditions and the permeability during the parameter identification process by experiment may not be consistent, in order to further improve the identification accuracy, the method of the present application also considers the parameter variation characteristics caused by magnetic field saturation, that is, under the excitation of the first excitation source, the first saturation coefficient K s1 at this time is calculated, the working condition is to simulate the permeability of the motor under the experimental working condition, under the excitation of the second excitation source, the second saturation coefficient K s2 at this time is calculated, the excitation voltage output by the second excitation source is the sine excitation voltage used by the motor under the actual working condition, and then the permeability of the motor under the actual working condition is simulated, and then the saturation coefficients of the two are compared. The identified parameters are corrected to the equivalent circuit parameters under the actual saturation state, so that the parameter identification accuracy is further improved.

[0054] In summary, compared with the conventional no-load locked-rotor parameter determination test, the present application has low equipment requirements, higher safety, and simpler operation, can directly identify all parameters of the large-capacity AC excitation motor, and compared with the conventional parameter identification test, the parameter variation characteristics caused by the magnetic field saturation can be considered, and the identification accuracy is higher. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 The figure is a flow chart of the transient parameter identification method for the large-capacity AC excitation motor for variable-speed pumped storage in the embodiment of the present application.

[0056] Figure 2 The figure is a flow chart of the transient parameter identification method for the large-capacity AC excitation motor for variable-speed pumped storage in the embodiment of the present application.

[0057] Figure 3 The figure is a schematic diagram of the rotor positioning test provided in the embodiment of the present application.

[0058] Figure 4 The figure is a schematic diagram of the rotor current waveform during the rotor positioning test provided in the embodiment of the present application.

[0059] Figure 5 The figure is a schematic diagram of the DC voltage step test provided in the embodiment of the present application.

[0060] Figure 6 is a schematic diagram of the stator and rotor current waveform when a direct current step voltage test is performed using the method provided in the embodiments of the present application.

[0061] Figure 7 is a second optimization result obtained using the method provided in the embodiments of the present application. DETAILED DESCRIPTION

[0062] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0063] In the present application, the terms "first", "second", etc. in the present application and the accompanying drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence.

[0064] Embodiment 1

[0065] As shown in the transient parameter identification method for large-capacity AC excitation motor for variable-speed pumped storage provided in the embodiments of the present application, the method mainly includes: Figure 1 S1, based on the operation circuit (mathematical model) of the large-capacity AC excitation motor for variable-speed pumped storage, a first frequency domain expression of the stator and rotor d-axis current under the excitation of the first excitation source is established; wherein the frequency domain expression contains the to-be-identified motor transient parameters; the operation circuit of the large-capacity AC excitation motor reflects the relationship between the voltage and current of the stator and rotor in the frequency domain.

[0066] S2, under the excitation of the first excitation source, the stator and rotor three-phase current waveform of the large-capacity AC excitation motor for variable-speed pumped storage is recorded, and the stator d-axis current waveform and the rotor d-axis current waveform are obtained based on the stator and rotor three-phase current waveform.

[0067] S3, the first frequency domain expression of the stator and rotor d-axis current is converted into a time domain form to obtain a time domain general solution form of the stator and rotor d-axis current; the corresponding stator and rotor d-axis current waveform is fitted in the time domain using the time domain general solution form of the stator and rotor d-axis current, and the expression after the time domain fitting is converted into a second frequency domain expression corresponding to the stator and rotor d-axis current.

[0068] S4, taking the principle that the coefficients in the second frequency domain expression are equal to the coefficients in the first frequency domain expression, the to-be-identified motor transient parameters contained in the first frequency domain expression are solved.

[0069]

[0070] ​It should be noted that the above steps S1-S4 are only one specific implementation, and do not limit the execution order of the above method, for example, S2 can also be executed before S1, and in the embodiment of the application, the scheme is specifically described in the execution order of S1-S4.

[0071] In the embodiment of the application, the first excitation source is a direct current step voltage, which can reduce the complexity of calculation, and in other embodiments, other excitation sources such as a sinusoidal excitation source can also be selected.

[0072] As a preferred implementation, in S1, a first frequency domain expression of the stator d-axis current under the excitation of the first excitation source is established based on the operating circuit (mathematical model) of the large-capacity AC excitation motor for variable-speed pumped storage, including:

[0073] Under the condition that the stator winding of the large-capacity AC excitation motor for variable-speed pumped storage is excited by the excitation voltage of the first excitation source, the rotor is zero excitation, and the rotor is static, the stator d-axis voltage equation is obtained;

[0074] The stator d-axis voltage equation and the operating circuit of the large-capacity AC excitation motor for variable-speed pumped storage are solved to obtain the transfer function of the stator d-axis voltage with respect to the stator d-axis current and the rotor d-axis current, that is, the frequency domain expression of the stator d-axis current and the rotor d-axis current, which is taken as the first frequency domain expression.

[0075] As a preferred, when the excitation voltage of the first excitation source is a direct current step voltage, the first frequency domain expression of the stator d-axis current and the rotor d-axis current is:

[0076]

[0077] Wherein, I ds (p) is the first frequency domain expression of the stator d-axis current, I dr (p) is the first frequency domain expression of the rotor d-axis current, and p represents an operation operator; U ds represents the stator d-axis voltage, L ss represents the steady-state inductance of the stator, L ss ′ represents the transient inductance of the stator, L m represents the mutual inductance between the windings in the dq coordinate system, T r represents the time constant of the rotor winding, T r ′ represents the transient time constant of the rotor winding, r s represents the resistance of the stator winding, r r represents the resistance of the rotor winding. The reactance parameters of the motor L ss , L ss ′, L m , and T r and T rAll are parameters to be identified, r s and r r Can be obtained by DC experiment, which can be considered as known quantities.

[0078] Specifically, in S2, comprising:

[0079] S21, align the three-phase winding axes of the stator and rotor of the large-capacity AC excitation motor for variable-speed pumped storage, complete the rotor positioning, and obtain the included angle of the three-phase winding axes. Figure 3 As shown in FIG. 1, it is a schematic diagram of a DC step voltage test rotor positioning method provided by an embodiment of the present application, which aims to align the three-phase windings of the stator and rotor and facilitate the subsequent coordinate transformation of the stator current and rotor current. Specifically, the rotor winding is opened, the rated frequency AC voltage is input into the stator winding A and B (in other embodiments, it can also be any two selected from the three phases), the rotor is slowly rotated, the oscilloscope is used to measure the rotor U and V (corresponding to the stator winding A and B) phase line voltage, and when the rotor U and V phase line voltage waveform amplitude appears the maximum value (as shown in FIG. 2), the rotation is stopped, at this time, the three-phase winding axes of the stator and rotor are aligned, and the rotor positioning is completed. Figure 4

[0080] S22, short the rotor winding, apply the excitation voltage of the first excitation source (the DC step voltage signal is adopted in the embodiment of the present application) to the stator A and B, and use the oscilloscope to record the stator A phase current response signal and the rotor U phase current response signal. As shown in FIG. 3, the rotor winding is shorted, the DC voltage Vs is applied to the A and B windings, the current clamp is placed at the stator A phase and the rotor U phase, and the stator A phase and the rotor U phase waveforms are recorded on the oscilloscope, as shown in FIG. 4. Figure 5 Figure 6

[0081] S23, based on the above-mentioned included angle of the three-phase winding axes, the stator A phase voltage, the stator A phase current and the rotor U phase current are converted from the abc three-phase coordinate system to the dq coordinate system to obtain the corresponding stator d-axis voltage, stator d-axis current and rotor d-axis current.

[0082] In the embodiment of the present application, the relationship between the stator d-axis voltage, the stator d-axis current, the rotor d-axis current and the stator A phase voltage, the stator A phase current and the rotor U phase current is as follows:

[0083]

[0084] Wherein, U a , I a , I u are the stator A phase voltage, the stator A phase current and the rotor U phase current measured by the test (recorded by the oscilloscope), U ds , I​​​ds , I dr are stator d-axis voltage, stator d-axis current, rotor d-axis current respectively.

[0085] As a preferred implementation, the first frequency domain expression of the stator d-axis current and the rotor d-axis current is converted into a time domain form, and the time domain general solution form of the stator d-axis current and the rotor d-axis current obtained is:

[0086]

[0087] Wherein, I ds (t) is the stator d-axis current at t moment, I dr (t) is the rotor d-axis current at t moment; A s , B s , A r , B r are amplitude coefficients of each exponential function, λ1, λ2 are attenuation coefficients of the exponential function, I ds∞ is the stable value of the stator d-axis current; A s , B s , A r , B r , λ1, λ2, I ds∞ are unknown variables.

[0088] In the embodiment of the application, the time domain fitting problem is converted into a multi-parameter two-target optimization problem, the difference between the sampling value and the fitting value of the stator d-axis current and the rotor d-axis current is taken as the optimization target, and an optimization algorithm is used to solve A s , B s , A r , B r , λ1, λ2, I ds∞ , and the expression after time domain fitting is obtained.

[0089] Specifically, the time domain general solution form of the stator d-axis current and the rotor d-axis current is used to perform time domain fitting on the corresponding stator d-axis current waveform and rotor d-axis current waveform, and the expression after time domain fitting is obtained, including:

[0090] The following optimization target is established:

[0091]

[0092] Wherein, J1 represents the difference between the sampling value and the fitting value of the stator d-axis current, and J2 represents the difference between the sampling value and the fitting value of the rotor d-axis current; I ds (t i ) and I ds ain (t i ) respectively represent the st

[0093] ator d-axis current at ti the sampling value and the fitting value of the current at time t dr (t i ) and I dr ain (t i ) respectively represent the rotor d-axis

[0094] the sampling value and the fitting value of the current at time t i s , B s , A r , B r , λ1, λ2, I ds∞ are to be optimized variables, N1 and N2 are respectively the sampling point numbers of the stator and rotor d-axis currents measured in the experiment, i.e. the numbers of points sampled for the stator and rotor d-axis currents.

[0095] The above objective function is solved by using an optimization algorithm to obtain the optimal A s , B s , A r , B r , λ1, λ2, I ds∞ , and the time-domain fitting is completed. In the embodiment of the application, the NSGA-II algorithm is used to solve the above objective function.

[0096] Specifically, after the expression fitted in the time domain is subjected to Laplace transform, it is converted into the corresponding second frequency-domain expressions of the stator and rotor d-axis currents, and the specific form is as follows:

[0097]

[0098] wherein α0, α1, β0, γ1, γ2 and γ3 respectively represent coefficients related to A s , B s , A r , B r , λ1, λ2 and I ds∞ .

[0099] As a preferred implementation, in S4, the to-be-identified motor transient parameters contained in the first frequency-domain expression are obtained by solving:

[0100]

[0101] wherein the values on the left side of the equal sign in the above formula can be obtained by parameter fitting on the experimental data, and can be considered as known quantities (i.e. the coefficients in the second frequency-domain expression) after the experiment is completed, the stator and rotor resistances (r s and r r ) can be obtained by direct current test and can be considered as known quantities, and the to-be-identified motor transient parameters contained in the first frequency-domain expression can be obtained by the above formula. ​

[0102] Furthermore, according to L ss =L m +L sl The stator leakage inductance L can be obtained. sl .

[0103] according to The rotor self-inductance L can be obtained. rr .

[0104] according to The transient inductance L' of the rotor winding when the stator winding is short-circuited can be obtained. rr .

[0105] according to The rotor leakage inductance L can be obtained. rl .

[0106] In this way, all parameters of a large-capacity AC excitation motor can be identified.

[0107] like Figure 7 The figure shows the optimization result of the method provided in the embodiment of the present invention. After obtaining the stator and rotor d-axis current waveforms, the NSGA-II algorithm is used for fitting. An error curve is formed during the iteration process. The points in the figure are the Pareto fronts of each generation. After the iteration is completed and converged, the individual closest to the origin in the 100th generation is selected, and the information on its chromosome is read. This is the target variable. According to the information on the chromosome, the complete parameters of the equivalent circuit of the large-capacity AC excitation motor can be obtained according to the method in S4 above.

[0108] As a further design of the present invention, considering that the permeability of the large-capacity AC excitation motor for variable-speed pumped storage under actual operating conditions may be inconsistent with the permeability obtained through parameter identification in experiments, in order to further improve the identification accuracy, the method of the present invention further includes:

[0109] S5. Parameter calibration steps, specifically including:

[0110] S51. A physical model of the large-capacity AC excitation motor for variable-speed pumped storage under test is established using finite element software.

[0111] S52. Under the excitation of the first excitation source, obtain the current magnetomotive force of the stator and rotor teeth, the air gap magnetomotive force, and the yoke magnetomotive force, in order to calculate the first saturation coefficient K at this time. s1 This operating condition simulates the permeability of the motor under the experimental condition S2 described above; preferably, the excitation voltage output by the first excitation source is a DC step voltage.

[0112] S53. Under the excitation of the second excitation source, obtain the current magnetomotive force of the stator and rotor teeth, the air gap magnetomotive force, and the yoke magnetomotive force, in order to calculate the second saturation coefficient K at this time. s2; wherein the excitation voltage output by the second excitation source is a sinusoidal excitation voltage used by the motor in the actual working condition, thereby simulating the magnetic permeability of the motor in the actual working condition; compared with the second saturation coefficient in the actual working condition, the first saturation coefficient is actually a non-saturation coefficient.

[0113] Specifically, the relationship between the stator tooth magnetic motive force, the air gap magnetic motive force, the yoke magnetic motive force and the saturation coefficient is:

[0114]

[0115] wherein F represents the magnetic motive force, and the subscripts δ, j1, j2, t1 and t2 represent the air gap, the stator yoke, the rotor yoke, the stator tooth and the rotor tooth, respectively.

[0116] S54, by comparing the saturation coefficients of the two, the above equivalent circuit parameters are corrected to the equivalent circuit parameters in the actual saturation state, and the correction formula is:

[0117]

[0118] wherein L1 is the motor reactance parameter before correction, including the steady-state inductance L ss of the stator, the transient inductance L ss of the stator, the mutual inductance L m between the stator and rotor in the dq coordinate system, the leakage inductance L sl of the stator, the self-inductance L rr of the rotor, the transient inductance L' rr of the rotor winding when the stator winding is short-circuited, and the leakage inductance L' rr of the rotor. That is, L1 takes L ss , L ss ', L m , L sl , L rr , L' rr , L rl in turn, and L2 corresponds to the corrected L ss , L ss ', L m , L sl , L rr , L' rr , L rl .

[0119] According to the formula: the corrected rotor winding time constant T r and the rotor winding transient time constant T r ' can be obtained.

[0120] The application first establishes a frequency domain expression of the stator and rotor d-axis currents under the excitation of a first excitation source (regard it as a first frequency domain expression) through an operation circuit (mathematical model) of the large-capacity AC excitation motor for variable-speed pumped storage; then obtains the stator and rotor d-axis current waveforms of the large-capacity AC excitation motor for variable-speed pumped storage under the excitation of the same excitation source, and performs time domain fitting on the stator and rotor d-axis current waveforms. In the time domain fitting, the time domain general solution form of the stator and rotor d-axis current waveforms in the time domain fitting can be obtained based on the frequency domain expression of the stator and rotor d-axis currents obtained by the operation circuit, and based on the time domain general solution form and the known stator and rotor d-axis current waveforms, the stator and rotor d-axis current waveform expression after the time domain fitting can be obtained. After converting the stator and rotor d-axis current waveform expression into a frequency domain, the obtained stator and rotor d-axis current waveform frequency domain expression is regarded as a second frequency domain expression, and the equivalent circuit parameters of the large-capacity AC excitation motor, that is, the motor transient parameters to be identified, can be obtained by comparing the coefficients of the first frequency domain expression and the second frequency domain expression. Compared with the traditional no-load locked-rotor parameter determination test, the application provides a new parameter identification method for the large-capacity AC excitation motor for variable-speed pumped storage. The parameters in the equivalent circuit are identified by the stator and rotor d-axis current frequency domain expressions obtained in the experiment, the first excitation source used in the experiment can only obtain the stator and rotor three-phase current waveforms of the large-capacity AC excitation motor for variable-speed pumped storage, without the need to pass a large current or voltage, and without the need for special protection devices. The application has low requirements for experimental equipment, is safer, is easier to operate, and has high identification accuracy without assuming that the stator and rotor leakage reactances are equal, which is consistent with the actual working condition.

[0121] Further, the method of the application also considers the parameter variation characteristics caused by magnetic field saturation, which can further improve the parameter identification accuracy.

[0122] Embodiment 2

[0123] The embodiment of the application provides a large-capacity AC excitation motor for variable-speed pumped storage transient parameter identification system, including a memory and a processor, the memory stores a computer program, and the processor realizes the steps of the method in the above embodiment 1 when executing the computer program.

[0124] The related technical solutions are the same as above, and will not be repeated here.

[0125] Embodiment 3

[0126] The embodiment of the application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the steps of the method in the above embodiment 1.

[0127] In particular, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one disk storage device, a flash storage device, or other volatile solid-state storage device.

[0128] The related technical solutions are the same as above, and will not be repeated here.

[0129] Embodiment 4

[0130] The embodiment of the present application provides a computer program product, comprising a computer program, when the computer program runs on a computer, so that the computer executes the steps of the method in the above embodiment 1.

[0131] The related technical solutions are the same as above, and will not be repeated here.

[0132] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage, characterized in that, include: Based on the operational circuit of the variable-speed pumped storage high-capacity AC excitation motor, a first frequency domain expression for the stator and rotor d-axis currents under the excitation of the first excitation source is established; wherein, the frequency domain expression contains the transient parameters of the motor to be identified; Under the excitation of the first excitation source, the stator and rotor three-phase current waveforms of the variable speed pumped storage large-capacity AC excitation motor are recorded to obtain the stator and rotor d-axis current waveforms accordingly. The first frequency domain expression of the stator and rotor d-axis currents is transformed into a time domain form to obtain the time domain general solution form of the stator and rotor d-axis currents; the time domain general solution form is used to perform time domain fitting on the corresponding stator and rotor d-axis current waveforms, and the time domain fitted expression is transformed into a frequency domain form to serve as the second frequency domain expression of the corresponding stator and rotor d-axis currents. Based on the principle that the coefficients in the second frequency domain expression are equal to the coefficients in the first frequency domain expression, the transient parameters of the motor to be identified contained in the first frequency domain expression are obtained by solving. When the excitation voltage of the first excitation source is a DC step voltage, the first frequency domain expression is: In the formula, , These are the first frequency domain expressions for the stator and rotor d-axis currents, respectively. Represents an operation operator; U ds This refers to the stator d-axis voltage; L ss For the steady-state inductance of the stator, For the transient inductance of the stator, L m The mutual inductance between the windings is the equivalent of the stator and rotor being coaxial in the dq coordinate system. T r The rotor winding time constant is The transient time constant of the rotor winding is... r s The resistance of the stator winding, r r The resistance of the rotor winding is denoted as ; where L ss , , L m , T r and All of these are parameters to be identified.

2. The method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage according to claim 1, characterized in that, Based on the operational circuit of the high-capacity AC excitation motor for variable-speed pumped storage, a first frequency domain expression for the stator and rotor d-axis currents under the excitation of the first excitation source is established, including: The stator d-axis voltage equation is obtained under the following conditions: the stator winding of the variable-speed pumped storage large-capacity AC excitation motor is excited by the excitation voltage of the first excitation source, the rotor is excited by zero excitation, and the rotor is stationary. By combining the stator d-axis voltage equation with the operational circuit of the variable-speed pumped storage high-capacity AC excitation motor, the first frequency domain expression of the stator and rotor d-axis currents is obtained.

3. The method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage according to claim 1, characterized in that, The time-domain general solution of the stator and rotor d-axis currents is as follows: In the formula, for Stator d-axis current at time t. for The rotor d-axis current at time 1; A s , B s , A r , B r These are the amplitude coefficients of each exponential function. , The decay coefficient of the exponential function is . Let be the stable value of the stator d-axis current; where, A s , B s , A r , B r , , , It is an unknown variable; The time-domain general solution is used to fit the corresponding stator and rotor d-axis current waveforms in the time domain, resulting in the time-domain fitted expressions, including: The following optimization objective function is established: in, This represents the difference between the sampled value and its fitted value of the stator d-axis current. This represents the difference between the sampled value and its fitted value of the rotor d-axis current; and These represent the stator d-axis currents at... The sampled values ​​and fitted values ​​at each time step; and These represent the rotor d-axis current at... The sampled values ​​and fitted values ​​at each time step; N 1. N 2 represents the number of sampling points for the stator and rotor d-axis currents, respectively; The objective function is solved using an optimization algorithm to obtain the optimal solution. A s , B s , A r , B r , , , We obtain the expression after time-domain fitting.

4. The method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage according to claim 3, characterized in that, The relationship between the coefficients in the second frequency domain expression and the motor transient parameters to be identified contained in the first frequency domain expression is as follows: In the formula, The coefficients are those in the second frequency domain expression, which is obtained by performing a Laplace transform on the time-domain fitted expression. L ss , , L m , T r and The parameter to be identified is denoted as .

5. The method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage according to claim 4, characterized in that, The parameters to be identified also include stator leakage inductance. Rotor self-inductance The transient inductance of the rotor winding when the stator winding is short-circuited and rotor leakage inductance Any one or more of the following; , , Determined by the following formula: ， ， 。 6. The transient parameter identification method for a large-capacity AC excitation motor for variable-speed pumped storage according to claim 5, characterized in that, It also includes correcting the identified parameters, specifically including: A physical model of the high-capacity AC excitation motor for variable-speed pumped storage was established using finite element software. Under the excitation of the first excitation source, the physical model obtains the current magnetomotive force of the stator and rotor teeth, the air gap magnetomotive force, and the yoke magnetomotive force, in order to calculate the first saturation coefficient at this time. ; The physical model, under the excitation of the second excitation source, obtains the current magnetomotive force of the stator and rotor teeth, the air gap magnetomotive force, and the yoke magnetomotive force, in order to calculate the second saturation coefficient at this time. Wherein, the excitation voltage output by the second excitation source is the sinusoidal excitation voltage used by the motor under actual operating conditions; Based on the first saturation coefficient and the second saturation coefficient Motor reactance parameters The corrected motor reactance parameters are obtained by performing calibration. The correction formula is as follows: In the formula, Take in sequence L ss , , L m , , , or , Corresponding to the corrected L ss , , L m , , , or ; Based on formula , The corrected rotor winding time constant is obtained. T r and the transient time constant of the rotor winding .

7. The method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage according to any one of claims 1-6, characterized in that, Under the excitation of the first excitation source, the stator and rotor three-phase current waveforms of the high-capacity AC excitation motor for variable speed pumped storage are recorded to obtain the stator and rotor d-axis current waveforms, including: Align the stator and rotor three-phase winding axes of the variable-speed pumped storage large-capacity AC excitation motor to obtain the included angle of the three-phase winding axes; wherein, aligning the stator and rotor three-phase winding axes of the variable-speed pumped storage large-capacity AC excitation motor includes: opening the rotor winding, applying an AC voltage of rated frequency to the A and B phases of the stator winding, rotating the rotor, measuring the rotor U and V phase line voltages using an oscilloscope, and stopping the rotor rotation when the amplitude of the rotor U and V phase line voltage waveforms reaches its maximum value, at which point the stator and rotor three-phase winding axes are aligned; After the stator and rotor three-phase winding axes are aligned, the rotor winding is short-circuited, and the excitation voltage of the first excitation source is applied to the stator A and B phases. The stator A phase current and the rotor U phase current are recorded using an oscilloscope. Based on the included angle of the three-phase winding axes, the stator A-phase current and rotor U-phase current are transformed from the abc three-phase coordinate system to the dq coordinate system to obtain the stator and rotor d-axis current waveforms.

8. A transient parameter identification system for a large-capacity AC excitation motor used in variable-speed pumped storage, characterized in that, Includes computer-readable storage media and processors; The computer-readable storage medium is used to store executable instructions; The processor is used to read executable instructions stored in the computer-readable storage medium and execute the transient parameter identification method for a large-capacity AC excitation motor for variable-speed pumped storage as described in any one of claims 1-7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the transient parameter identification method for a large-capacity AC excitation motor for variable-speed pumped storage as described in any one of claims 1-7.

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