Method and electronic equipment for non-intrusive identification of parameters of induction motor

Abstract

The embodiment of the invention relates to a non-intrusive method for identifying parameters of an induction motor and electronic equipment. The method comprises the following steps: acquiring a transient voltage, a transient current and a starting process duration of the starting process of the induction motor under a synchronous dq coordinate; obtaining a feasible region of an estimator of the resistance of the stator winding and an estimator of the leakage inductance of the stator winding, and generating a two-dimensional search grid; equivalent resistance and equivalent reactance of the induction motor at a real load operation point are obtained; constructing an induction motor impedance circle by using the feasible region and the equivalent resistance and the equivalent reactance at the real load operation point; and calculating an objective function of each grid point in the two-dimensional search grid, searching stator resistance and stator inductance of a global optimal grid point enabling the objective function value to be minimum, and obtaining an impedance parameter of the induction motor. According to the embodiment of the invention, the impedance circle diagram of the induction motor is adopted, the number of solving equations is increased, the difficulty of impedance parameter solving is reduced, and non-intrusive parameter identification is realized.

Description

TECHNICAL FIELD

[0001] The present patent relates to the technical field of induction motor parameter identification, and particularly relates to a method for non-invasively identifying parameters of an induction motor and an electronic device. BACKGROUND

[0002] Induction motors are the most numerous and largest power equipment in industrial enterprises, and their safe, reliable and efficient operation is very important to industrial production processes. The correct analysis and evaluation of the defect development degree, fault state and energy efficiency level of the induction motor depend on accurate impedance parameters and mechanical parameters.

[0003] However, in order to ensure production continuity, the managers of enterprises usually do not allow the motors to be stopped at will, and it is difficult to measure the parameters of the induction motor through locked-rotor test and no-load test in time. The induction motor will change the contact point area or air gap due to maintenance and other reasons, resulting in deviation of the real parameters from the factory parameters. During the daily normal starting process, the windings of most induction motors will also be deformed due to the action of a large electromagnetic force, thereby causing the impedance parameters to change. Therefore, under the realistic condition restrictions that the locked-rotor test and the no-load test cannot be performed when the motors are stopped, and the nameplate information or the factory information cannot reflect the current motor parameters, a non-invasive online identification method for the parameters of the induction motor must be constructed.

[0004] For a long time, there are the following difficulties in the realization and industrial application of the non-invasive online identification method for the impedance parameters and mechanical parameters of the induction motor:

[0005] 1) The number of induction motors is huge, and it is impossible to install a speed measuring disc on each motor, so that the accurate speed of each induction motor cannot be obtained;

[0006] 2) The steady-state T-shaped equivalent circuit impedance parameters to be solved of the induction motor are five, but there are only two mesh equations available, which makes it difficult to solve the impedance parameters;

[0007] 3) The method of approximating the current circle diagram by using the starting transient waveform can supplement the number of equations, but it is difficult to obtain accurate steady-state phasor due to the change of the grid voltage.

[0008] These difficulties limit the research and development progress of the non-invasive online identification method for the impedance parameters and mechanical parameters of the induction motor and the corresponding industrial products. SUMMARY

[0009] In order to solve the technical problems that the motor parameters are difficult to be accurately identified online due to the inability to stop for testing, the lack of speed measurement, the fluctuation of grid voltage and the insufficient number of model solving equations in the prior art, the embodiments of the present application propose a method for non-invasively identifying parameters of an induction motor and an electronic device.

[0010] According to a first aspect of the present invention, the non-invasive method for identifying parameters of an induction motor includes:

[0011] Obtain the transient voltage during the starting process of the induction motor in synchronous dq coordinates. Transient current during startup and startup process duration ;

[0012] The estimated value of the stator winding resistance of the induction motor is obtained. Estimation of stator winding leakage inductance feasible domain, ,in, This is the equivalent resistance of the induction motor at the stall point. The equivalent inductance of the induction motor at the stall point is calculated, and a two-dimensional search grid is generated.

[0013] The induction motor was obtained at its actual load operating point. equivalent resistance and equivalent reactance ;

[0014] Utilizing the equivalent resistance of the induction motor at the stall point and equivalent inductance and the induction motor at the actual load operating point equivalent resistance and equivalent reactance Construct the impedance circle of the induction motor;

[0015] Based on the impedance circle of the induction motor, calculate the objective function for each grid point in the two-dimensional search grid. Find the value of the objective function. Minimum global optimal grid point stator resistance and stator inductor ;

[0016] Based on the obtained global optimal grid points and The impedance parameters of the induction motor are obtained.

[0017] In some embodiments, the stator winding resistance of the induction motor is obtained. estimator and stator winding leakage inductance estimator The feasible domain includes:

[0018] The equivalent resistance at the stall point within a few cycles after the power supply switch of the induction motor is turned on is obtained. and equivalent inductance , take the starting process transient voltage of the induction motor in the time period and starting process transient current , configuration:

[0019] ,

[0020] ,

[0021] ,

[0022] wherein, is the moment of the locked-rotor operating point, at which the slip S of the induction motor is 1,

[0023] is the angular frequency of the grid voltage,

[0024] is the number of the sampling point, is the sampling moment of the sampling point,

[0025] by least square method:

[0026] ,

[0027] obtained , and further the equivalent resistance and equivalent inductance of the induction motor at the locked-rotor operating point are obtained,

[0028] .

[0029] In some embodiments, the equivalent resistance and equivalent reactance of the induction motor at the real load operating point are obtained by the following formula,

[0030] ,

[0031] wherein, represents the average value after summing the data of multiple sampling points satisfying .

[0032] In some embodiments, the induction motor impedance circle is a locus circle formed by the steady-state impedance of the induction motor varying with the slip of the induction motor in the complex plane,

[0033] ,

[0034] the center coordinate of the induction motor impedance circle , radius parameter and the induction motor impedance parameter relationship is:

[0035] ,

[0036] According to the locked-rotor operating point, the real load operating point of the induction motor impedance circle, and its geometric relationship on the induction motor trajectory circle, and an estimated value of the stator winding resistance with a set value , the estimated value of the stator winding resistance corresponding to the center coordinate of the induction motor impedance circle and the radius estimate is:

[0037] ,

[0038] wherein, is the stator winding resistance of the induction motor,

[0039] is the estimated value of the stator winding resistance of the induction motor with a set value,

[0040] is the rotor resistance of the induction motor,

[0041] is the stator leakage reactance of the induction motor,

[0042] is the rotor leakage reactance of the induction motor,

[0043] is the excitation reactance of the induction motor,

[0044] is the equivalent reactance of the induction motor at the known locked-rotor operating point, is the grid voltage angular frequency.

[0045] In some embodiments, the target function of each grid point in the two-dimensional search grid is calculated according to the induction motor impedance circle , and the stator resistance and the stator inductance of the global optimal grid point that makes the target function value minimum are found, including:

[0046] Based on the relationship between the equivalent resistance of the induction motor at the stall point and the stator and rotor resistances And the fundamental relationship between equivalent reactance and stator and rotor reactance. The estimated value of the rotor resistance of the induction motor is obtained. The estimated value of the rotor leakage reactance of the induction motor rotor. and the estimated amount of the excitation reactance of the induction motor :

[0047] ,

[0048] ,

[0049] ; and further,

[0050] The stator winding self-inductance of the induction motor in synchronous dq coordinates is obtained. The excitation inductance of the induction motor in synchronous dq coordinates and the rotor winding self-inductance of the induction motor in synchronous dq coordinates ;

[0051] Based on the estimated value of the stator winding resistance of the induction motor The stator winding self-inductance of the induction motor in synchronous dq coordinates The excitation inductance of the induction motor in synchronous dq coordinates and the transient voltage of the induction motor during startup obtained in synchronous dq coordinates. and transient current during startup The estimated value of the rotor current of the induction motor in the synchronous dq coordinate system is obtained. and ;

[0052] Based on the estimated value of the stator winding resistance of the induction motor Estimated value of rotor resistance The stator winding self-inductance of the induction motor in synchronous dq coordinates The rotor winding self-inductance of the induction motor in synchronous dq coordinates The excitation inductance of the induction motor in synchronous dq coordinates And the estimate of rotor current and The slip rate of the induction motor is obtained. ;

[0053] Based on the transient voltage during the starting process of the induction motor in synchronous dq coordinates and the starting process transient current , the instantaneous power absorbed by the induction motor is obtained , and an estimate of the instantaneous electromagnetic power supplied on the stator side of the induction motor and an estimate of the instantaneous electromagnetic power absorbed on the rotor side of the induction motor are obtained

[0054] the objective function value is calculated , , all the grid points in the two-dimensional search grid are traversed to find the stator resistance and the stator inductance of the globally optimal grid point that minimizes the objective function value .

[0055] In certain embodiments, characterized in that an estimate of the field inductance of the induction motor , an estimate of the stator winding leakage inductance L 0s of the induction motor , an estimate of the rotor leakage inductance L 0r of the induction motor , the field inductance of the induction motor in synchronous dq coordinates , the stator winding self-inductance of the induction motor in synchronous dq coordinates and the rotor winding self-inductance of the induction motor in synchronous dq coordinates ;

[0056] an estimate of the rotor current of the induction motor in synchronous dq coordinates and are:

[0057] ,

[0058] wherein denotes the convolution operation;

[0059] the slip of the induction motor is:

[0060] ;

[0061] the instantaneous power absorbed by the induction motor is: ;

[0062] an estimate of the instantaneous electromagnetic power supplied on the stator side of the induction motor and an estimate of the instantaneous electromagnetic power absorbed on the rotor side of the induction motor are respectively:

[0063] ,

[0064] .

[0065] 7. The method of non-invasive identification of induction motor parameters according to any one of claims 1-6, wherein the obtaining the impedance parameters of the induction motor according to the obtained and of the globally optimal grid point comprises:

[0066] obtaining the impedance parameters of the globally optimal grid point of the induction motor, the induction motor impedance circle parameters, the rotor current , the slip and the electromagnetic power of the globally optimal grid point of the induction motor, the induction motor impedance circle parameters comprising the globally optimal grid point of the induction motor induction motor impedance circle center coordinates and the globally optimal grid point of the induction motor impedance circle radius ; obtaining the rated slip and the rated power

[0067] of the rated operating point of the induction motor based on the globally optimal grid point of the induction motor induction motor impedance circle center coordinates and the globally optimal grid point of the induction motor impedance circle radius . In some embodiments, the obtaining the impedance parameters of the induction motor according to the obtained and

[0068] of the globally optimal grid point further comprises: obtaining the slip of the globally optimal grid point of the induction motor, and

[0069] obtaining the rate of change of the slip of the induction motor by first-order difference according to the slip of the globally optimal grid point of the induction motor:

[0070]

[0071] ,

[0072] wherein, is the electromagnetic torque curve of the induction motor, is the mechanical torque curve of the induction motor,

[0073] obtaining the constraint relationship:

[0074] ,

[0075] constructing

[0076] ,

[0077] ,

[0078] ,

[0079] by least square method

[0080] ,

[0081] obtained , so that the mechanical load parameters and the rotor moment of inertia including the mechanical torque coefficient and the constant torque component coefficient are:

[0082]

[0083] In some embodiments, the impedance parameters of the induction motor are obtained according to the obtained and of the global optimal grid point, and the method further comprises:

[0084] the rated slip and the rated power of the induction motor, so that the inertia time constant ,

[0085] .

[0086] According to a second aspect of the present application, the electronic device comprises: a processor; and a memory storing instructions which, when executed by the processor, cause the device to perform the method as described above.

[0087] The method of the embodiments of the present application has the following beneficial effects:

[0088] The induction motor impedance circle diagram according to the embodiments of the present application is used to reflect the relationship between the equivalent impedance of the reaction induction motor and the slip, the number of equations is increased, the difficulty of solving the impedance parameters is reduced, and the non-intrusive parameter identification is realized. Moreover, since the induction motor impedance circle diagram is independent of the voltage size, the defect that the current circle diagram in the prior art is affected by the grid voltage is avoided.

[0089] ​The embodiment of the present application does not need to rely on the rotating speed measuring device, avoids the problem of difficult installation of the tachometer, realizes the non-intrusive parameter identification of the induction motor equipment in the production occasion, can save the implementation cost, and reduces the product promotion difficulty in the production enterprise. The embodiment of the present application also avoids the influence of the locked-rotor / no-load test on the production, overcomes the dependence on the factory nameplate parameters, provides real-time and accurate data basis for motor state monitoring, energy efficiency evaluation and fault diagnosis, and has great engineering application value. BRIEF DESCRIPTION OF DRAWINGS

[0090] Figure 1 is a principle diagram of the non-intrusive identification method of the impedance parameters of the induction motor proposed by the embodiment of the present application;

[0091] Figure 2 is a schematic diagram of the impedance circle of the induction motor in the non-intrusive identification method of the impedance parameters of the induction motor proposed by the embodiment of the present application;

[0092] Figure 3 is a relationship diagram of the rated slip of the rated operating point of the induction motor in the impedance circle of the induction motor in the non-intrusive identification method of the impedance parameters of the induction motor proposed by the embodiment of the present application;

[0093] Figure 4 is a principle diagram of the mechanical load parameter and rotor rotational inertia identification method of the induction motor proposed by the embodiment of the present application;

[0094] Figure 5 and Figure 6 is the relationship between the formulas and variables in the non-intrusive identification method of the impedance parameters of the induction motor proposed by the embodiment of the present application. DETAILED DESCRIPTION

[0095] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below, and reference is made to the drawings. However, those skilled in the art know that the present application is not limited to the drawings and the following embodiments.

[0096] As described herein, the term "comprising" and its various variants can be understood as an open term, which means "including but not limited to". The term "based on" and its similar expressions can be understood as "at least based on". The terms "first", "second", "third" and the like expressions are only used to distinguish different features, and have no substantial meaning. The terms "left", "right", "middle" and their similar expressions are only used to represent the positional relationship between the relative objects.

[0097] The purpose of the present application is to overcome the difficulties and deficiencies of the prior art, and to propose a method and electronic equipment for non-intrusive identification of induction motor parameters.

[0098] According to a first aspect of the present application, the method for non-invasive identification of induction motor parameters comprises the following steps:

[0099] S1: Collecting the starting waveform data of the induction motor, and identifying the impedance parameters of the induction motor.

[0100] S1.1: Obtaining the starting process transient voltage , the starting process transient current and the starting process duration of the induction motor in the synchronous dq coordinate, to obtain the instantaneous power absorbed by the induction motor.

[0101] Obtaining the starting process transient voltage , the starting process transient current and the starting process duration of the induction motor in the synchronous dq coordinate.

[0102] In this embodiment, the values of a plurality of discrete sampling points are collected to form continuous signal data. There are equivalent operation and processing methods between continuous signals and discrete time sequences in the undergraduate textbook Signal and System in the field of electrical and electronic engineering.

[0103] Specifically, the starting process transient voltage , the starting process transient current and the starting process duration of the induction motor in the synchronous dq coordinate are obtained, wherein , is the number of sampling points, is the sampling time of the sampling point, to obtain the starting process transient voltage , the starting process transient current and the starting process duration of the induction motor in the synchronous dq coordinate.

[0104] Further, the instantaneous power absorbed by the induction motor is obtained.

[0105] Similarly, according to the equivalent operation and processing methods between continuous signals and discrete time sequences, the above discrete instantaneous power sequence may also be described in the form of a continuous signal

[0106] .

[0107] S1.2: Obtaining the estimated value s of the stator winding resistance R and the stator winding leakage inductance L0s estimator The feasible region is thus generated into a two-dimensional search grid.

[0108] Calculate the stall point (slip) within a few cycles (2-3 cycles, or even longer, depending on the motor capacity and rotor inertia time constant, typically 0.04-0.08 seconds) after the power supply switch of the induction motor is turned on. The equivalent resistance (when the rotor speed is almost zero) and equivalent inductance ,Pick Transient voltage during the starting process of an induction motor within a certain time period Transient current during startup ,structure:

[0109] ,

[0110] ,

[0111] .

[0112] in, This refers to the stall point (speed close to 0, slip rate) within 2-3 cycles after the power supply switch of the induction motor is turned on. (the moment); The derivative of the stator current with respect to time can be calculated using finite difference methods.

[0113] Using the least squares method:

[0114] ,

[0115] It can be obtained Thus, the equivalent resistance of the induction motor at the stall point can be obtained. and equivalent inductance ,

[0116] .

[0117] in, and These represent the real and imaginary parts of a complex number, respectively. Desirable Or take , The angular frequency of the grid voltage. This refers to the grid voltage frequency.

[0118] Total resistance of the stator and rotor of an induction motor Equivalent resistance The values are approximately equal, and at a speed close to 0 the rotor branch impedance is much smaller than the excitation branch impedance, so in principle it can be approximated that

[0119] ;

[0120] Total leakage inductance of the stator and rotor of an induction motor Equivalent inductance The values are approximately equal, and at a speed close to 0 the rotor branch impedance is much smaller than the excitation branch impedance, so in principle it can be approximated that

[0121] ;

[0122] denotes the stator winding resistance, denotes the rotor resistance; denotes the stator winding leakage inductance, denotes the rotor leakage inductance.

[0123] The estimate of the stator winding resistance of the induction motor is obtained by using the symbol superscript "hat" to denote an estimate, and is given by The estimate of the stator winding leakage inductance of the induction motor is obtained by using the symbol superscript "hat" to denote an estimate, and is given by The feasible region of the decision variable

[0124] .

[0125] A two-dimensional search grid of N = 100 is generated from the feasible region of the estimate of the stator winding resistance and the estimate of the stator winding leakage inductance for use in S1.4. S1.3: Obtain the equivalent resistance and the equivalent reactance of the induction motor at the real load operating point

[0126] . The equivalent resistance and the equivalent reactance of the induction motor at the real load operating point

[0127] are calculated as

[0128] ​​​,

[0129] in, This means taking the average value, that is, first considering the conditions that satisfy... Total indivual Sum the data and then divide by the total. .

[0130] At actual load operating points The induction motor starting process has ended, the rotor speed no longer increases, and the slip rate... Size is .

[0131] S1.4: Utilizing the equivalent resistance of the induction motor at the stall point and equivalent inductance and the induction motor at the actual load operating point equivalent resistance and equivalent reactance Construct the impedance circle of the induction motor and calculate the objective function for each grid point in the two-dimensional search grid. This continues until all grid points in the two-dimensional search grid are traversed to find the value of the objective function. Minimum global optimal grid point stator resistance and stator inductor .

[0132] Preferably, calculations can be performed starting from the grid center to reduce the amount of computation. The specific steps are as follows:

[0133] 1) Set the initial values ​​of the stator winding resistance and stator winding leakage inductance to the center of the two-dimensional search grid, i.e. Pick This is the initial value.

[0134] 2) Construct the impedance circle of the induction motor to obtain an estimate of the rotor resistance of the induction motor. The estimated value of the rotor leakage reactance of the induction motor rotor. and the estimated amount of the excitation reactance of the induction motor .

[0135] Construct an impedance circle for the induction motor, where the impedance circle represents the steady-state impedance of the induction motor. With rotational variation The circle of trajectory formed by the change on the complex plane. The center of the impedance circle of the induction motor is... , radius is in,

[0136] ,

[0137] By transforming equation (11) into the form of the equation of a circle in the complex plane, the coordinate parameters of the circle's center can be obtained. radius parameters Relationship between the impedance parameters of the induction motor

[0138] ,

[0139] .

[0140] The stator resistance of the induction motor is [value missing]. Let be the rotor resistance of the induction motor. The stator leakage reactance of the induction motor is... The rotor leakage reactance of the induction motor is... The excitation reactance of the induction motor is... Let be the slip of the induction motor. (Equation) , , and Figure 2 The use of the symbol without the superscript "^" in the text is intended to illustrate the principle relationship between the equivalent impedance of an induction motor and the impedance circle.

[0141] like Figure 2 As shown, the equivalent resistance of the induction motor at the stall point is The equivalent reactance of the induction motor at the stall point is The induction motor operates at the actual load point. The equivalent resistance is The induction motor operates at the actual load point The equivalent reactance is .

[0142] In setting Assuming the stator winding resistance Rs is an estimate, based on the stall point and the actual load point on the impedance circle of the induction motor, and... Geometric relationship between center and radius (see) Figure 2 The estimated coordinates of the center of the impedance circle of the induction motor can be calculated. and radius estimate for:

[0143] .

[0144] The estimated radius of the impedance circle obtained from the calculation and estimated rotor leakage reactance , substituting an estimate of the excitation reactance of the induction motor :

[0145] .

[0146] from the formula of the principle relationship , so combining the formula an estimate of the rotor resistance of the induction motor an estimate of the rotor leakage reactance of the rotor of the induction motor and an estimate of the excitation reactance of the induction motor :

[0147] .

[0148] 3) from the relationship of the reactance and the inductance, an estimate of the excitation inductance L ms of the induction motor an estimate of the stator winding leakage inductance L 0s of the induction motor an estimate of the rotor leakage inductance L 0r of the induction motor from the transformation relationship between the abc coordinates and the synchronous dq coordinates known in the motor science, the excitation inductance of the induction motor in the synchronous dq coordinates, the stator winding self-inductance of the induction motor in the synchronous dq coordinates and the rotor winding self-inductance of the induction motor in the synchronous dq coordinates:

[0149] .

[0150] from the estimate of the stator winding resistance of the induction motor the stator winding self-inductance of the induction motor in the synchronous dq coordinates, the excitation inductance of the induction motor in the synchronous dq coordinates and the obtained starting process transient voltage and starting process transient current of the induction motor in the synchronous dq coordinates, from the constraint relationship between the rotor current and the stator voltage, the stator current of the induction motor in the synchronous dq coordinates, an estimate of the rotor current of the induction motor in the synchronous dq coordinates and :

[0151] ,

[0152] In the above formulae, denotes a convolution operation, is the angular frequency of the grid voltage. According to the undergraduate textbook "Signals and Systems" in the field of electrical and electronic engineering, the convolution operation is well known. According to the undergraduate textbook "Signals and Systems", the equivalence between continuous signal operations and discrete signal operations is also well known, so that the , and and described in the above paragraph using the continuous time t can also be described using the discrete time t k .

[0153] 4) From the estimate of the stator winding resistance of the induction motor , the estimate of the rotor resistance , the self-inductance of the stator winding of the induction motor in the synchronous dq coordinates , the self-inductance of the rotor winding of the induction motor in the synchronous dq coordinates , the magnetizing inductance of the induction motor in the synchronous dq coordinates the estimate of the rotor current and , and the estimate of the time derivative of the rotor current and , (obtained by differentiation), the slip is obtained as:

[0154] .

[0155] 5) The estimate of the instantaneous electromagnetic power supplied on the stator side of the induction motor and the estimate of the instantaneous electromagnetic power absorbed on the rotor side

[0156]

[0157] .

[0158] In the above formulae , , see the formulae , , .

[0159] 6) Calculate the objective function value

[0160] ,

[0161] Traverse all grid points in the two-dimensional search grid to find the global optimal grid point that makes the objective function value The minimum stator resistance and stator inductance .

[0162] S1.5: According to the obtained global optimal grid point , the global optimal defined resistance and stator leakage inductance , calculate other impedance and inductance parameters corresponding to the global optimal grid point of the induction motor, induction motor impedance circle parameters, rotor current, slip and electromagnetic power, the induction motor impedance circle parameters include the global optimal grid point of the induction motor corresponding to the induction motor impedance circle center coordinates and the global optimal grid point corresponding to the induction motor impedance circle radius .

[0163] 1) Substitute the and obtained from the optimal global optimal grid point into the formula The formula Calculate the other impedance and inductance parameters of the global optimal grid point of the induction motor, including: rotor resistance , global optimal inductance parameter and reactance parameter ;

[0164] 2) Substitute , , , into the formula Calculate the global optimal grid point corresponding to the induction motor impedance circle center coordinates and the global optimal grid point corresponding to the induction motor impedance circle radius ;

[0165] 3) Substitute , , and known into the formula Calculate the rotor current corresponding to the global optimal grid point of the induction motor ;

[0166] 4) Substitute , , and known into the equation to calculate the slip corresponding to the globally optimal grid point of the induction motor ;

[0167] 5) Substitute , , and known into the equation to calculate the instantaneous electromagnetic power of the globally optimal grid point of the induction motor .

[0168] S1.6: Based on the center coordinates of the induction motor impedance circle corresponding to the globally optimal grid point of the induction motor and the radius of the induction motor impedance circle corresponding to the globally optimal grid point , calculate the rated slip and the rated power of the rated operating point of the induction motor.

[0169] According to the geometric relationship diagram of the induction motor impedance circle Figure 4 and its rated operating point with a rated slip , the induction motor has a rated slip at the rated operating point, and the impedance angle of the induction motor at the rated operating point is the smallest (see tangent of the induction motor impedance circle in Figure 3 ), thus, according to the geometric relationship between the tangent of the circle and the center of the circle:

[0170] 1) Obtain the rated power factor and the rated impedance of the induction motor as follows:

[0171] ;

[0172] 2) Obtain the rated current and the rated input power of the induction motor as follows:

[0173] ,

[0174] In the above formula, is the rated voltage of the induction motor, which is the rated voltage of the power grid at the transient voltage collection point during the starting process of the induction motor.

[0175] 3) According to the , , , , obtaining an equation group of rotor-side current and rotor-side rated input power ,

[0176] ,

[0177] ,

[0178] Note that only two unknown parameters and are contained in two equations of formula , and and can be solved by solving the two equations. By substituting formula into formula , the rated slip of the induction motor can be solved.

[0179] ,

[0180] By substituting formula into formula , the rated power can be solved. Finally, by substituting into formula , the rated power of the induction motor can be solved.

[0181] .

[0182] S2: According to the impedance parameters of the induction motor, the mechanical load parameters, rotor moment of inertia and inertia time constant of the induction motor are obtained.

[0183] S2.1: According to the impedance parameters of the induction motor, the mechanical load coefficient and rotor moment of inertia of the induction motor are obtained, and the mechanical load coefficient of the induction motor includes mechanical torque coefficient and constant torque component coefficient .

[0184] According to the slip of the global optimal grid point of the induction motor, the change rate of the slip of the induction motor is obtained by first-order difference.According to the rate of change of the slip of the induction motor , the instantaneous electromagnetic power of the global optimal grid point and the rotor motion equation, a least square model parameter identification model is constructed to calculate the mechanical load parameter and rotor moment of inertia of the induction motor .

[0185] Specifically,

[0186]

[0187] ,

[0188] Among them, is the electromagnetic torque curve of the induction motor, is the mechanical torque curve of the induction motor.

[0189] The constraint relationship is obtained:

[0190] ,

[0191] The construction is:

[0192] ,

[0193] ,

[0194] ,

[0195] The value of X can be obtained by the known least square method

[0196]

[0197] , that is, the value of on the left side of the equal sign . Therefore, substituting X into , the mechanical load parameter and rotor moment of inertia are obtained as:

[0198]

[0199] S2.2: Obtain the inertia time constant of the induction motor

[0200] According to the rated slip of the induction motor obtained by the formula , the formula , the rated power​ , calculate the inertial time constant is:

[0201]

[0202] The method of the embodiment of the application effectively overcomes the problem of more parameters to be solved and less equations available by specific algorithm design, and eliminates the influence of power grid voltage change on the accuracy of steady-state phasor calculation, thereby realizing high-precision, non-intrusive online identification of impedance parameters and mechanical parameters of the motor under normal operation state.

[0203] In a second aspect of the application, there is provided an electronic device comprising: a processor; and memory storing instructions that, when executed by the processor, cause the device to perform the method described above.

[0204] In a third aspect of the application, there is provided a computer-readable storage medium storing machine-readable instructions that, when executed by the machine, cause the machine to perform the method described above.

[0205] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In the specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0206] The above describes the embodiments of the application. However, the application is not limited to the above-described embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method of non-intrusively identifying parameters of an induction motor, the method comprising: The method includes: Obtaining transient voltages of an induction motor during start-up in synchronous dq coordinates , transient currents during start-up , and start-up duration ; obtaining an estimate of the stator winding resistance of the induction motor and an estimate of the stator winding leakage inductance a feasible region, wherein, is an equivalent resistance of the induction motor at a locked-rotor operating point, is an equivalent inductance of the induction motor at a locked-rotor operating point, and generating a two-dimensional search grid; The induction motor was obtained at its actual load operating point. equivalent resistance and equivalent reactance ; Utilizing the equivalent resistance of the induction motor at the stall point and equivalent inductance and the induction motor at the actual load operating point equivalent resistance and equivalent reactance Construct the impedance circle of the induction motor; According to the induction motor impedance circle, a target function of each grid point in the two-dimensional search grid is calculated , the stator resistance and the stator inductance of the global optimal grid point that makes the target function value minimum are found; According to the obtained global optimal grid points and , the impedance parameters of the induction motor are obtained.

2. The method of non-invasively identifying parameters of an induction motor of claim 1, wherein, The stator winding resistance of the induction motor is obtained. estimator and stator winding leakage inductance estimator The feasible domain includes: to obtain an equivalent resistance of the locked-rotor operating point of the induction motor within a few cycles after the power supply switch of the induction motor is turned on and an equivalent inductance , taking a start-up process transient voltage of the induction motor within a period of time and a start-up process transient current , a configuration: ， ， ， wherein, is the time instant of the locked-rotor operating point, at which the slip S of the induction motor at the locked-rotor operating point is 1, Vgridis the grid voltage angular frequency, is the number of the sampling point, is the sampling time of the sampling point, Using the least squares method: ， are obtained , and further the equivalent resistance and the equivalent inductance of the induction motor at the locked-rotor operating point, 。 3. The method for non-invasive identification of induction motor parameters as described in claim 1, characterized in that, The induction motor at the real load operating point the equivalent resistance and the equivalent reactance are obtained by the following equations, ， wherein, represents the average of the data of the plurality of sampling points satisfying the sum of the data of the plurality of sampling points satisfying​ 4. The method for non-invasive identification of induction motor parameters as described in claim 1, characterized in that, The induction motor impedance circle is a steady state impedance of the induction motor As the slip of the induction motor changes The locus circle formed on the complex plane as the slip of the induction motor changes, ， The center coordinates of the induction motor impedance circle , radius parameters and the induction motor impedance parameters are related as , from the geometric relations of the locked-rotor operating point, the real load operating point of the induction motor impedance circle and their geometric relations on the induction motor locus circle, and an estimated value of the stator winding resistance set with a numerical value , the estimated value of the stator winding resistance can be calculated , the estimated value of the center coordinates of the corresponding induction motor impedance circle , and the estimated value of the radius are: ， wherein R is the stator winding resistance of the induction motor, an estimated amount of stator winding resistance set for the induction motor, Let be the rotor resistance of the induction motor. for the stator leakage reactance of the induction motor, for the rotor leakage reactance of the induction motor, for the excitation reactance of the induction motor, for the equivalent reactance of the induction motor at a known locked-rotor operating point, for the grid voltage angular frequency.

5. The method for non-invasive identification of induction motor parameters as described in claim 4, characterized in that, The target function of each grid point in the two-dimensional search grid is calculated according to the induction motor impedance circle , finding the stator resistance and the stator inductance of the global optimal grid point that makes the target function value minimum, comprising: from the relationship between the equivalent resistance of the induction motor at the blocked-rotor operating point and the stator resistance and the rotor resistance and the principle relationship between the equivalent reactance and the stator reactance and the rotor reactance an estimate of the rotor resistance of the induction motor an estimate of the rotor leakage reactance of the rotor of the induction motor and an estimate of the excitation reactance of the induction motor : ， ， ; and further, a stator winding self-inductance of the induction motor in synchronous dq coordinates a magnetizing inductance of the induction motor in synchronous dq coordinates and a rotor winding self-inductance of the induction motor in synchronous dq coordinates ; an estimate of the stator winding resistance of the induction motor , the stator winding self-inductance of the induction motor in synchronous dq coordinates , the excitation inductance of the induction motor in synchronous dq coordinates and the acquired transient voltage of the induction motor during start-up in synchronous dq coordinates and the transient current during start-up , an estimate of the rotor current of the induction motor in synchronous dq coordinates and ; an estimate of the stator winding resistance of the induction motor an estimate of the rotor resistance an estimate of the stator winding self-inductance of the induction motor in synchronous dq coordinates an estimate of the rotor winding self-inductance of the induction motor in synchronous dq coordinates an estimate of the excitation inductance of the induction motor in synchronous dq coordinates an estimate of the rotor current and an estimate of the slip of the induction motor ; transient voltage of an induction motor during a start-up process in synchronous dq coordinates and a transient current of a start-up process , obtaining an instantaneous power absorbed by the induction motor and an estimate of an instantaneous electromagnetic power supplied on the stator side of the induction motor and an estimate of an instantaneous electromagnetic power absorbed on the rotor side of the induction motor ; Computing the objective function value , , traversing all grid points in the two-dimensional search grid to find a global optimal grid point that minimizes the objective function value the stator resistance and the stator inductance .

6. The method for non-invasive identification of induction motor parameters as described in claim 5, characterized in that, The estimated value of the excitation inductance of the induction motor The stator winding leakage inductance L of the induction motor 0s estimator The rotor leakage inductance L of the induction motor 0r estimator The excitation inductance of the induction motor in synchronous dq coordinates The stator winding self-inductance of the induction motor in synchronous dq coordinates and the rotor winding self-inductance of the induction motor in synchronous dq coordinates ; An estimate of the rotor current of the induction motor in synchronous dq coordinates and is: ， wherein denotes a convolution operation; The slip of the induction motor is: ； the instantaneous power absorbed by the induction motor is: ; an estimate of the instantaneous electromagnetic power supplied to the stator side of the induction motor and an estimate of the instantaneous electromagnetic power absorbed by the rotor side respectively: ， 。 7. The method for non-invasive identification of induction motor parameters as described in any one of claims 1-6, characterized in that, the global optimal grid points are obtained according to the global optimal grid points and obtaining impedance parameters of the induction motor, comprising: According to the obtained global optimal grid point of the induction motor and , impedance parameters of the global optimal grid point of the induction motor, induction motor impedance circle parameters, rotor current , slip and electromagnetic power of the global optimal grid point of the induction motor are obtained, the induction motor impedance circle parameters including induction motor impedance circle center coordinates and induction motor impedance circle radius of the global optimal grid point of the induction motor. a center coordinate of an induction motor impedance circle based on the globally optimal grid point of the induction motor a radius of the induction motor impedance circle of the globally optimal grid point a rated slip of the rated operating point of the induction motor and a rated power .

8. The method for non-invasive identification of induction motor parameters as described in claim 7, characterized in that, The global optimal grid point is obtained according to the global optimal grid point obtained in the step of obtaining the global optimal grid point And The impedance parameters of the induction motor are obtained, and the method further comprises: a slip of the global optimum grid point of the induction motor , a first-order difference is taken to obtain a rate of change of the slip of the induction motor : ， wherein is the electromagnetic torque curve of the induction motor, is the mechanical torque curve of the induction motor, The constraint relationship is obtained as follows: ， structure ， ， ， Using the least squares method ， The values of the mechanical torque coefficient and the constant torque component coefficient are obtained from the following equations: where the mechanical load parameter and the rotor moment of inertia are:

9. The method for non-invasive identification of induction motor parameters as described in claim 8, characterized in that, The global optimal grid point is obtained according to the global optimal grid point obtained in the step of obtaining the global optimal grid point And The impedance parameters of the induction motor are obtained, and the method further comprises: According to a rated slip of the induction motor , a rated power , an inertia time constant of the induction motor is obtained , 。 10. An electronic device, comprising: include: processor; And a memory storing instructions that, when executed by the processor, cause the device to perform the method according to any one of claims 1-9.

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