Method and system for identifying transient parameters of high-capacity alternating-current excitation motor for variable-speed pumping and storage

Abstract

The invention belongs to the technical field of motor parameter identification, and discloses a transient parameter identification method and system for a high-capacity alternating-current excitation motor for variable-speed pumping and storage, and the method comprises the steps: building a first frequency domain expression of d-axis current of a stator and a rotor under the excitation of a first excitation source based on an operational circuit of the high-capacity alternating-current excitation motor for variable-speed pumping and storage; d-axis current waveforms of the stator and the rotor are obtained under excitation of the first excitation source, time domain fitting is carried out on the d-axis current waveforms of the stator and the rotor by utilizing a time domain general solution form of the d-axis current waveforms, and the expression after time domain fitting is converted into a frequency domain form to serve as a second frequency domain expression of d-axis current of the stator and the rotor; and obtaining a to-be-identified motor transient parameter based on the two frequency domain expressions. The parameter identification method has the advantages of being low in required equipment requirement, higher in safety, simpler to operate and capable of directly identifying all parameters of the large-capacity alternating-current excitation motor, and compared with a traditional parameter identification test, parameter change characteristics caused by magnetic field saturation can be considered, and the identification precision is higher.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor parameter identification, and more specifically, relates to a method and system for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage. Background Art

[0002] One of the main features of the new power system is the widespread access to a high proportion of renewable energy. The proportion of renewable energy power, mainly wind, light and other new energy sources, has increased significantly. However, the random volatility of new energy sources has brought great challenges to the safety and stability of the new power system. In order to cope with the challenges brought by the random volatility of new energy sources, large-scale energy storage technology is vigorously developed to solve the problem of grid connection and absorption of new energy sources. Among them, pumped storage is the most economical, most mature and most suitable energy storage technology for large-scale development.

[0003] The equivalent circuit parameters of large-capacity AC excitation motors used in variable-speed pumped storage directly affect their power regulation range and response speed to the power grid. Therefore, the new power system puts forward higher requirements for the accuracy of the design of parameters of large-capacity AC excitation motors. After the motor is manufactured, it is necessary to measure the parameters of the motor to verify the accuracy of the parameter design. At present, the most well-known parameter measurement method of the doubly fed motor is the no-load and locked-rotor test mentioned in the IEEE standard. However, for the no-load and locked-rotor test of large-capacity AC excitation motors for variable-speed pumped storage, the voltage level of the required voltage regulator is relatively high, and the current introduced during the experiment is relatively large. There are problems such as high requirements for equipment, high test difficulty and low safety, and the stator and rotor leakage reactance parameters are difficult to accurately calculate (in the no-load and locked-rotor tests, the stator and rotor leakage reactance are assumed to be equal, but the two are not equal under actual working conditions), which makes it difficult to be applied to the parameter measurement of large-capacity AC excitation motors. If a parameter determination method with high safety, low test difficulty and low equipment requirements can be proposed for large-capacity AC excitation motors for variable-speed pumped storage to guide the electromagnetic design of large-capacity AC excitation motors, it will be beneficial to give full play to the supporting role of large-capacity AC excitation motors for new power systems. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a method and system for transient parameter identification of a large-capacity AC excitation motor for a variable-speed pumped storage battery, with the aim of providing a parameter identification method for a large-capacity AC excitation motor for a variable-speed pumped storage battery with high safety, low test difficulty, and low equipment requirements, and improving the accuracy of parameter identification.

[0005] To achieve the above object, according to a first aspect of the present invention, a method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage is provided, comprising:

[0006] Based on the operation circuit of the variable speed pumped storage large capacity AC excitation motor, 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 motor transient parameters to be identified;

[0007] 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 obtain the corresponding stator and rotor d-axis current waveforms;

[0008] Converting the first frequency domain expressions of the stator and rotor d-axis currents into a time domain form to obtain a time domain general solution form of the stator and rotor d-axis currents; performing time domain fitting on the corresponding stator and rotor d-axis current waveforms using the time domain general solution form, and converting the expressions after time domain fitting into a frequency domain form to serve as a second frequency domain expression of the corresponding stator and rotor d-axis currents;

[0009] 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 solved.

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

[0011] The stator winding of the variable speed pumped storage large capacity AC excitation motor is excited by inputting the excitation voltage of the first excitation source, the rotor is zero-excited, and the stator d-axis voltage equation is obtained under the experimental conditions of the rotor being stationary;

[0012] The stator d-axis voltage equation and the operation circuit of the variable-speed pumped storage large-capacity AC excitation motor are combined to obtain the first frequency domain expression of the stator and rotor d-axis currents.

[0013] Furthermore, when the excitation voltage of the first excitation source is a DC step voltage, the first frequency domain expression is:

[0014]

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

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

[0017]

[0018] In the formula, I ds (t) is the stator d-axis current at time t, I dr (t) is the rotor d-axis current at time t; A s , B s , A r , B r is the amplitude coefficient of each exponential function, λ1 and λ2 are the attenuation coefficients of the exponential function, I ds∞ is the stable value of the stator d-axis current; where A s , B s , A r , B r ,λ1,λ2,I ds∞ is an unknown variable;

[0019] The time domain general solution form is used to perform time domain fitting on the corresponding stator and rotor d-axis current waveforms to obtain expressions after time domain fitting, including:

[0020] The following optimization objective function is established:

[0021]

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

[0023] Sub-d-axis current at t i The sampling value and fitting value at the moment; I dr (t i ) and I dr ain (t i ) represent the rotor d axis

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

[0025] The optimization algorithm is used to solve the objective function and obtain the optimal A s , B s , A r , B r ,λ1,λ2,I ds∞ , and get the expression after time domain fitting.

[0026] Further, 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:

[0027]

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

[0029] Furthermore, the parameters to be identified also include stator leakage inductance L sl 、Rotor self-inductance L rr , the transient inductance L' of the rotor winding when the stator winding is short-circuited rr And rotor leakage inductance L rl Any one or more of the following;

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

[0031]

[0032] Furthermore, the identified parameters are corrected, including:

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

[0034] The physical model obtains the current stator and rotor teeth magnetomotive force, air gap magnetomotive force and yoke magnetomotive force under the excitation of the first excitation source to calculate the first saturation coefficient K at this time. s1 ;

[0035] The physical model obtains the current stator and rotor teeth magnetomotive force, air gap magnetomotive force and yoke magnetomotive force under the excitation of the second excitation source 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 under actual working conditions;

[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 a 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 , 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 Get the corrected rotor winding time constant T r , and the rotor winding transient time constant T r ′.

[0040] Furthermore, 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 obtain the stator and rotor d-axis current waveforms correspondingly, including:

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

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

[0043] Based on the angle between the axes of the three-phase winding, 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 stator and rotor d-axis current waveforms.

[0044] According to a second aspect of the present invention, there is provided a system for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage, 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 transient parameter identification method of a large-capacity AC excitation motor for variable-speed pumped storage as described in any one of the first aspects.

[0047] According to a third aspect of the present invention, there is provided a computer-readable storage medium having a computer program stored thereon, wherein when the program is executed by a processor, the method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage is implemented as described in any one of the first aspects.

[0048] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0049] (1) The present invention first establishes the frequency domain expression of the stator and rotor d-axis current under the excitation of the first excitation source through the operation circuit (mathematical model) of the large-capacity AC excitation motor for variable speed pumped storage to be tested (taking it as the first frequency domain expression); then, under the excitation of the same excitation source, the stator and rotor d-axis current waveforms of the large-capacity AC excitation motor for variable speed pumped storage to be tested are obtained, and the stator and rotor d-axis current waveforms are fitted in the time domain. During the fitting, the frequency domain expression of the stator and rotor d-axis current obtained by the operation circuit can be used to obtain the time domain general solution form of the stator and rotor d-axis current waveform during the time domain fitting. 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 expressions after time domain fitting can be obtained. After converting it into the frequency domain, the obtained frequency domain expression of the stator and rotor d-axis current waveform is used 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, that is, the transient parameters of the motor to be identified, can be obtained. Compared with the traditional no-load stall parameter measurement test, the present invention provides a new parameter identification method for large-capacity AC excitation motors for variable-speed pumped storage. The frequency domain expressions of the stator and rotor d-axis currents obtained in the experimental process are used to identify the parameters in the equivalent circuit. The first excitation source used in the experimental process only needs to be able to obtain the three-phase current waveforms of the stator and rotor of the large-capacity AC excitation motor for variable-speed pumped storage. There is no need to pass a large current or voltage, and no special protection device is required. The equipment required for the experiment is low, the safety is higher, and the operation is simpler. In addition, in the identification process, there is no need to assume that the stator and rotor leakage reactances are equal, which is consistent with the actual working conditions and has high identification accuracy.

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

[0051] (3) As a preferred method, when performing time domain fitting, the time domain fitting problem is transformed into a multi-parameter two-objective optimization problem, with the minimum difference between the sampling value and the fitting value of the stator and rotor d-axis current as the optimization goal, and the optimization algorithm is used to solve A s , B s , A r , B r ,λ1,λ2,I ds∞ , we can get the expression after time domain fitting.

[0052] (4) Furthermore, the identification method of the present invention can identify the steady-state inductance L of the stator. ss , the transient inductance of the stator L ss ′, the mutual inductance L between the stator and rotor coaxial equivalent windings in the dq coordinate system m , stator leakage inductance L sl 、Rotor self-inductance L rr, the transient inductance L' of the rotor winding when the stator winding is short-circuited rr And rotor leakage inductance L rl The motor reactance parameters including the rotor winding time constant T can also be identified. r and the rotor winding transient time constant T r ′, the identification of all parameters of large-capacity AC excitation motors is realized. There is no need to assume that the stator and rotor leakage reactances are equal. The actual stator and rotor leakage reactances can be identified with higher identification accuracy.

[0053] (5) Furthermore, considering that the magnetic permeability of the large-capacity AC excitation motor for variable-speed pumped storage in actual working conditions may be inconsistent with the magnetic permeability in the parameter identification process through experiments, in order to further improve the identification accuracy, the method of the present invention also considers the parameter change characteristics caused by magnetic field saturation, that is, the first saturation coefficient K is calculated under the excitation of the first excitation source. s1 This condition simulates the magnetic permeability of the motor under experimental conditions. The second saturation coefficient K is calculated under the excitation of the second excitation source. s2 The excitation voltage output by the second excitation source is the sinusoidal excitation voltage used by the motor under actual working conditions, thereby simulating the magnetic permeability of the motor under actual working conditions, and then comparing the saturation coefficients of the two, and correcting the identified parameters to the equivalent circuit parameters under the actual saturation state, thereby further improving the parameter identification accuracy.

[0054] In summary, compared with the traditional no-load stall parameter measurement test, the present invention has lower equipment requirements, higher safety, and simpler operation. It can directly identify all parameters of large-capacity AC excitation motors. Compared with traditional parameter identification tests, it can consider the parameter change characteristics caused by magnetic field saturation, and has higher identification accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The present invention is a flow chart of a method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage in an embodiment of the present invention.

[0056] Figure 2 The present invention is a flowchart of a method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage considering saturation in an embodiment of the present invention.

[0057] Figure 3 A schematic diagram of a rotor positioning test provided in an embodiment of the present invention.

[0058] Figure 4 Schematic diagram of rotor current waveform during rotor positioning test provided by an embodiment of the present invention.

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

[0060] Figure 6 The figure is a schematic diagram of the stator and rotor current waveforms during the DC step voltage test provided by the embodiment of the present invention.

[0061] Figure 7 This is an optimization result after adopting the method provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

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

[0064] Example 1

[0065] like Figure 1 As shown, the method for identifying transient parameters of a large-capacity AC excitation motor for variable speed pumped storage provided in an embodiment of the present invention mainly includes:

[0066] S1. Based on the operational circuit (mathematical model) of a 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 a first excitation source is established; wherein the frequency domain expression contains the transient parameters of the motor to be identified; the operational 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.

[0067] S2. Under the excitation of the first excitation source, the stator and rotor three-phase current waveforms of the large-capacity AC excitation motor for variable-speed pumped storage are 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 waveforms.

[0068] S3. Convert the first frequency domain expression of the stator and rotor d-axis current into a time domain form to obtain the time domain general solution form of the stator and rotor d-axis current; use the time domain general solution form of the stator and rotor d-axis current to perform time domain fitting on the corresponding stator and rotor d-axis current waveforms, and convert the expressions after time domain fitting into the corresponding second frequency domain expression of the stator and rotor d-axis current.

[0069] S4. 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.

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

[0071] In the embodiment of the present invention, the first excitation source is a DC step voltage, which can reduce the complexity of calculation. In other embodiments, other excitation sources, such as a sinusoidal excitation source, can also be selected.

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

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

[0074] By combining the stator d-axis voltage equation and the operational circuit of the large-capacity AC excitation motor for variable-speed pumped storage, the transfer functions of the stator d-axis voltage and the stator d-axis current and the rotor d-axis current are obtained, that is, the frequency domain expressions of the stator d-axis current and the rotor d-axis current, which are used as the first frequency domain expression.

[0075] Preferably, when the excitation voltage of the first excitation source is a DC step voltage, the first frequency domain expressions of the stator d-axis current and the rotor d-axis current are:

[0076]

[0077] Among them, 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, p represents the operation operator; U ds Indicates 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 equivalent mutual inductance between the stator and rotor windings in the dq coordinate system, T r represents the rotor winding time constant, T r ′ represents the transient time constant of the rotor winding, r s represents the resistance of the stator winding, r r Indicates the resistance of the rotor winding. The reactance parameter L of the motor ss , L ss ′, L m and T r and T r′ are parameters to be identified, r s and r r It can be obtained through DC experiments and can be considered as a known quantity.

[0078] Specifically, S2 includes:

[0079] S21, align the stator and rotor three-phase winding axes of the variable speed pumped storage large capacity AC excitation motor, complete the rotor positioning, and obtain the angle of the three-phase winding axes. Figure 3 The figure shows a schematic diagram of a DC step voltage test rotor positioning method provided by an embodiment of the present invention, the purpose of which is to align the stator and rotor three-phase windings and facilitate the subsequent coordinate transformation of the stator current and the rotor current. Specifically, it includes: opening the rotor winding, applying an AC voltage of rated frequency to the motor stator winding A and B phases (in other embodiments, two phases can be selected from the three phases), slowly rotating the rotor, and using an oscilloscope to measure the rotor U and V (corresponding to the stator winding A and B) phase line voltages. When the rotor U and V phase line voltage waveform amplitudes reach the maximum value (such as Figure 4 As shown), the rotation stops, at which point the axes of the stator and rotor three-phase windings are aligned, completing the rotor positioning.

[0080] S22, short-circuit the rotor winding, apply the excitation voltage of the first excitation source to the stator phases A and B (the embodiment of the present invention uses a DC step voltage signal), and use an oscilloscope to record the stator A phase current response signal and the rotor U phase current response signal. Figure 5 As shown in FIG. 1 , it is a schematic diagram of a DC step voltage test provided by an embodiment of the present invention. The rotor winding is short-circuited, a DC voltage Vs is applied to the A and B two-phase windings, a current clamp is placed between the stator A phase and the rotor U phase, and the waveforms of the stator A phase and the rotor U phase are recorded on an oscilloscope. Figure 6 shown.

[0081] S23. Based on the angle of the above 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 invention, 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:

[0083]

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

[0085] As a preferred implementation, the first frequency domain expressions of the stator and rotor d-axis currents are converted into time domain forms, and the obtained time domain general solutions of the stator and rotor d-axis currents are:

[0086]

[0087] Among them, I ds (t) is the stator d-axis current at time t, I dr (t) is the rotor d-axis current at time t; A s , B s , A r , B r is the amplitude coefficient of each exponential function, λ1 and λ2 are the 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∞ is an unknown variable.

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

[0089] Specifically, the corresponding stator and rotor d-axis current waveforms are fitted in the time domain using the time domain general solution form of the stator and rotor d-axis currents to obtain expressions after time domain fitting, including:

[0090] The following optimization goals are established:

[0091]

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

[0093] Sub-d-axis current at ti The sampling value and fitting value at the moment; I dr (t i ) and I dr ain (t i ) represent the rotor d axis

[0094] Current at t i The sampling value and fitting value at time A s , B s , A r , B r ,λ1,λ2,I ds∞ is the variable to be optimized, N1 and N2 are the sampling points of the stator and rotor d-axis currents measured in the experiment, that is, the number of points for sampling the stator and rotor d-axis currents respectively.

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

[0096] Specifically, the expression after time domain fitting is converted into the corresponding second frequency domain expression of the stator and rotor d-axis current after Laplace transformation, and the specific form is:

[0097]

[0098] Among them, α0, α1, β0, γ1, γ2, and γ3 represent the s , B s , A r , B r ,λ1,λ2,I ds∞ The coefficient of correlation.

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

[0100]

[0101] The values ​​on the left side of the equal sign in the above equation can be obtained by fitting the test data. After the experiment, they can be considered as known quantities (i.e., the coefficients in the second frequency domain expression). s and r r ) can be obtained through DC tests and can be considered as a known quantity. The above formula can be used to obtain the transient parameters of the motor to be identified contained in the first frequency domain expression.

[0102] Furthermore, according to L ss =L m +L sl , we can get the stator leakage inductance L 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, the identification of all parameters of large-capacity AC excitation motors is achieved.

[0107] like Figure 7 As shown, it is an optimization result after adopting the method provided by the embodiment of the present invention. After obtaining the stator and rotor d-axis current waveforms, the NSGA-Ⅱ algorithm is used for fitting, and an error curve is formed in the iterative process. The points in the figure are all Pareto frontiers of each generation. After the iteration completes convergence, the individual closest to the origin in the 100th generation is selected, and the information on its chromosome is read, which is the required target variable. According to the information on the chromosome, all parameters of the equivalent circuit of the large-capacity AC excitation motor can be obtained according to the above-mentioned S4 method.

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

[0109] S5, parameter correction step, specifically including:

[0110] S51, using finite element software to establish a physical model of a large-capacity AC excitation motor for variable-speed pumped storage to be tested;

[0111] S52, under the excitation of the first excitation source, the current stator and rotor teeth magnetomotive force, air gap magnetomotive force and yoke magnetomotive force are obtained to calculate the first saturation coefficient K at this time s1 ; This working condition simulates the magnetic permeability of the motor under the experimental working condition of S2 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, the current stator and rotor teeth magnetomotive force, air gap magnetomotive force and yoke magnetomotive force are obtained to calculate the second saturation coefficient K at this time s2; Among them, the excitation voltage output by the second excitation source is the sinusoidal excitation voltage used by the motor under actual working conditions, thereby simulating the magnetic permeability of the motor under actual working conditions; compared with the second saturation coefficient under actual working conditions, the first saturation coefficient is actually a non-saturation coefficient.

[0113] Specifically, the relationship between the stator and rotor teeth magnetomotive force, the air gap magnetomotive force, the yoke magnetomotive force and the saturation coefficient is:

[0114]

[0115] Wherein, F represents magnetomotive force, and subscripts δ, j1, j2, t1 and t2 represent air gap, stator yoke, rotor yoke, stator teeth and rotor teeth respectively.

[0116] S54. Compare the saturation coefficients of the two, and correct the above equivalent circuit parameters to the equivalent circuit parameters under the actual saturation state. The correction formula is:

[0117]

[0118] Among them, L1 is the motor reactance parameter before correction, including the steady-state inductance L of the stator ss , the transient inductance of the stator L ss ′, the equivalent mutual inductance L between the stator and rotor windings in the dq coordinate system m , stator leakage inductance L sl , rotor self-inductance L rr , the transient inductance L' of the rotor winding when the stator winding is short-circuited rr , rotor leakage inductance L' rr That is, L1 takes L ss , L ss ′, L m , L sl , L rr , L' rr , L rl When 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 can be obtained r , and the rotor winding transient time constant T r ′.

[0120] The present invention first establishes the frequency domain expression of the stator and rotor d-axis current under the excitation of the first excitation source through the operation circuit (mathematical model) of the large-capacity AC excitation motor for variable speed pumped storage to be tested (taking it as the first frequency domain expression); then, under the excitation of the same excitation source, the stator and rotor d-axis current waveforms of the large-capacity AC excitation motor for variable speed pumped storage to be tested are obtained, and the stator and rotor d-axis current waveforms are fitted in the time domain. During the fitting, the frequency domain expression of the stator and rotor d-axis current obtained by the operation circuit can be used to obtain the time domain general solution form of the stator and rotor d-axis current waveform during the time domain fitting. 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 expressions after time domain fitting can be obtained. After converting it into the frequency domain, the obtained frequency domain expression of the stator and rotor d-axis current waveform is used 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, that is, the transient parameters of the motor to be identified, can be obtained. Compared with the traditional no-load stall parameter measurement test, the present invention provides a new parameter identification method for large-capacity AC excitation motors for variable-speed pumped storage. The frequency domain expressions of the stator and rotor d-axis currents obtained in the experimental process are used to identify the parameters in the equivalent circuit. The first excitation source used in the experimental process only needs to be able to obtain the three-phase current waveforms of the stator and rotor of the large-capacity AC excitation motor for variable-speed pumped storage. There is no need to pass a large current or voltage, and no special protection device is required. The equipment required for the experiment is low, the safety is higher, and the operation is simpler. In addition, in the identification process, there is no need to assume that the stator and rotor leakage reactances are equal, which is consistent with the actual working conditions and has high identification accuracy.

[0121] Furthermore, the method of the present invention also takes into account the parameter variation characteristics caused by magnetic field saturation, which can further improve the parameter identification accuracy.

[0122] Example 2

[0123] An embodiment of the present invention provides a transient parameter identification system for a large-capacity AC excitation motor for variable-speed pumped storage, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method in the above-mentioned embodiment 1 when executing the computer program.

[0124] The relevant technical solutions are the same as above and will not be described in detail here.

[0125] Example 3

[0126] An embodiment of the present invention provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method in the above-mentioned embodiment 1 are implemented.

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

[0128] The relevant technical solutions are the same as above and will not be described in detail here.

[0129] Example 4

[0130] An embodiment of the present application provides a computer program product, including a computer program. When the computer program is run on a computer, the computer executes the steps of the method in the above-mentioned embodiment 1.

[0131] The relevant technical solutions are the same as above and will not be described in detail here.

[0132] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

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 operation circuit of the variable speed pumped storage large capacity AC excitation motor, 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 motor transient parameters to be identified; 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 obtain the corresponding stator and rotor d-axis current waveforms; Converting the first frequency domain expressions of the stator and rotor d-axis currents into a time domain form to obtain a time domain general solution form of the stator and rotor d-axis currents; performing time domain fitting on the corresponding stator and rotor d-axis current waveforms using the time domain general solution form, and converting the expressions after time domain fitting into a frequency domain form to serve as a 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 solved.

2. The method for identifying transient parameters of a large-capacity AC excitation motor for variable speed pumped storage according to claim 1 is characterized in that: Based on the operation circuit of the variable speed pumped storage large capacity AC excitation motor, a first frequency domain expression of the stator and rotor d-axis current under the excitation of the first excitation source is established, including: The stator winding of the variable speed pumped storage large capacity AC excitation motor is excited by inputting the excitation voltage of the first excitation source, the rotor is zero-excited, and the stator d-axis voltage equation is obtained under the experimental conditions of the rotor being stationary; The stator d-axis voltage equation and the operation circuit of the variable-speed pumped storage large-capacity AC excitation motor are combined to obtain the first frequency domain expression of the stator and rotor d-axis currents.

3. The method for identifying transient parameters of a large-capacity AC excitation motor for variable speed pumped storage according to claim 2, characterized in that: When the excitation voltage of the first excitation source is a DC step voltage, the first frequency domain expression is: In the formula, I ds (p), I dr (p) are the first frequency domain expressions of the stator and rotor d-axis currents, respectively, and p represents the 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 equivalent mutual inductance between the stator and rotor windings in the dq coordinate system, T r is the rotor winding time constant, T r ′ is the transient time constant of the rotor winding, r s is the resistance of the stator winding, r r is the resistance of the rotor winding; where L ss , L ss ′, L m , T r and T r ′ are parameters to be identified.

4. The method for identifying transient parameters of a large-capacity AC excitation motor for variable speed pumped storage according to claim 3 is characterized in that: The time domain general solution of the stator and rotor d-axis currents is: In the formula, I ds (t) is the stator d-axis current at time t, I dr (t) is the rotor d-axis current at time t; A s , B s , A r , B r is the amplitude coefficient of each exponential function, λ1 and λ2 are the attenuation coefficients of the exponential function, I ds∞ is the stable value of the stator d-axis current; where A s , B s , A r , B r ,λ1,λ2,I ds∞ is an unknown variable; The time domain general solution form is used to perform time domain fitting on the corresponding stator and rotor d-axis current waveforms to obtain expressions after time domain fitting, including: The following optimization objective function is established: Wherein, J1 represents the difference between the sampled value of the stator d-axis current and its fitting value, and J2 represents the difference between the sampled value of the rotor d-axis current and its fitting value; I ds (t i ) and I ds_ain (t i ) represent the stator d-axis current at t i The sampling value and fitting value at the moment; I dr (t i ) and I dr_ain (t i ) represent the rotor d-axis current at t i The sampling value and fitting value at the moment; N1 and N2 are the number of points for sampling the stator and rotor d-axis currents respectively; The optimization algorithm is used to solve the objective function and obtain the optimal A s , B s , A r , B r ,λ1,λ2,I ds∞ , and get the expression after time domain fitting.

5. The method for identifying transient parameters of a large-capacity AC excitation motor for variable speed pumped storage according to claim 4 is 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: Wherein, α0, α1, β0, γ1, γ2, γ3 are coefficients in the second frequency domain expression, wherein the second frequency domain expression is obtained by performing Laplace transform on the expression after the time domain fitting; L ss , L ss ′, L m , T r and T r ' is the parameter to be identified.

6. The method for identifying transient parameters of a large-capacity AC excitation motor for variable speed pumped storage according to claim 5, characterized in that: The parameters to be identified also include stator leakage inductance L sl 、Rotor self-inductance L rr , the transient inductance L' of the rotor winding when the stator winding is short-circuited rr And rotor leakage inductance L rl Any one or more of the following; L sl , L rr , L' rr Determined by the following formula: L ss =L m +L sl , 7. The method for identifying transient parameters of a large-capacity AC excitation motor for variable speed pumped storage according to claim 6, characterized in that: It also includes correcting the identified parameters, including: A physical model of the large-capacity AC excitation motor for variable-speed pumped storage is established using finite element software; The physical model obtains the current stator and rotor teeth magnetomotive force, air gap magnetomotive force and yoke magnetomotive force under the excitation of the first excitation source to calculate the first saturation coefficient K at this time. s1 ; The physical model obtains the current stator and rotor teeth magnetomotive force, air gap magnetomotive force and yoke magnetomotive force under the excitation of the second excitation source 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 under actual working conditions; Based on the first saturation coefficient K s1 and the second saturation coefficient K s2 The motor reactance parameter L1 is corrected to obtain a corrected motor reactance parameter L2; wherein the correction formula is: In the formula, L1 takes L ss , L ss ′, L m , L sl , L rr , L' rr or L rl , L2 corresponds to the corrected L ss , L ss ′, L m , L sl , L rr , L' rr or L rl ; Based on the formula Get the corrected rotor winding time constant T r , and the rotor winding transient time constant T r ′.

8. 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 to 7, characterized in that: 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 obtain the corresponding stator and rotor d-axis current waveforms, including: The axes of the stator and rotor three-phase windings of the variable speed pumped storage large-capacity AC excitation motor are aligned to obtain the angle of the axes of the three-phase windings; wherein, the axes of the stator and rotor three-phase windings of the variable speed pumped storage large-capacity AC excitation motor are aligned, including: opening the rotor winding, applying an AC voltage of rated frequency to the stator winding A and B phases, rotating the rotor, measuring the rotor U and V phase line voltages with an oscilloscope, and stopping the rotor when the waveform amplitudes of the rotor U and V phase line voltages reach a maximum value, at which time the axes of the stator and rotor three-phase windings are aligned; After the axes of the stator and rotor three-phase windings are aligned, the rotor winding is short-circuited, the excitation voltage of the first excitation source is applied to the stator phases A and B, and the stator A phase current and the rotor U phase current are recorded using an oscilloscope; Based on the angle between the axes of the three-phase winding, 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 stator and rotor d-axis current waveforms.

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

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by the processor, the method for identifying transient parameters of a large-capacity AC excitation motor for variable-speed pumped storage is implemented as described in any one of claims 1 to 8.

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