Method for detecting rotor position of synchronous motor of pumped storage power plant

Abstract

The invention discloses a method for detecting the position of a synchronous motor rotor of a pumped storage power plant. A sliding-mode observer is adopted to replace a sensor to estimate the position and speed of the synchronous motor rotor of the pumped storage power plant so as to realize closed-loop control of a synchronous motor system of the pumped storage power plant. According to stator voltage and current measured by a motor model, rotor position information of the synchronous motor of the pumped storage power plant in the starting stage is obtained by adopting an injection pulsating high-frequency voltage method, the position and speed of the synchronous rotor of the pumped storage power plant in the medium-high speed stage are estimated with higher precision by utilizing an improved sliding mode observer, and then motor vector control is completed. Phase delay of the sliding-mode observer can be compensated, rotor position information in the starting stage of the synchronous motor of the pumped storage power plant is obtained, the buffeting phenomenon is eliminated and phase lag is avoided through the improved sliding-mode observer, and the rotor position information of the synchronous motor of the pumped storage power plant is obtained. And the rotor position and speed of the synchronous motor of the pumped storage power plant in the medium-high speed stage are estimated with higher precision.

Description

Technical Field

[0001] The invention relates to the field of synchronous motor rotor position detection in a pumped storage power plant, in particular to a method for detecting the rotor position of a synchronous motor in a pumped storage power plant. Background Art

[0002] At present, the position detection of the synchronous motor rotor in the pumped storage power plant is mainly monitored and estimated by sensors. The use of Hall position sensors as rotor position information detection devices not only increases the difficulty of motor installation, but also increases system costs and reduces system reliability.

[0003] The sliding mode observer has the advantages of fast dynamic response characteristics and strong robustness. It can feedback the current position of the rotor in real time and is widely used in permanent magnet synchronous motor control systems. However, due to the frequent start and stop of pumped storage power station units, complex working conditions, and component vibration, the rotor position information will have a great impact. The existing sliding mode observer detection method designs a sliding mode observer based on the mathematical model of the permanent magnet synchronous motor in the α and β two-phase stationary coordinate system; the sliding surface is selected, and the estimated value of the rotor position is obtained through the back electromotive force, but the back electromotive force signal extracted from the sliding mode observer needs to be processed by a low-pass filter, resulting in a lag in the rotor position information, thereby affecting the control performance and making the detected rotor position information inaccurate. Therefore, it is urgent to develop an effective method for calculating the rotor position of the synchronous motor of the pumped storage power station unit through a sliding mode observer to cope with the use scenarios where the pumped storage power station unit is frequently started and stopped, the working conditions are complex, and the component vibration will have a great impact on the rotor position information. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting the rotor position of a synchronous motor of a pumped storage power plant. The present invention can be applied to synchronous motors of pumped storage power plants, eliminate the vibration phenomenon and avoid phase lag, and can estimate the position and speed of synchronous rotors of pumped storage power plants at medium and high speed stages with higher accuracy.

[0005] The technical solution of the present invention is a method for detecting the rotor position of a synchronous motor in a pumped storage power plant, comprising the following steps:

[0006] S1, according to the electromotive force e of the surface permanent magnet synchronous motor α and e β , stator α, β axis current i α 、i β , stator α, β axis voltage u α 、u β , R S is the resistance of the motor stator, L is the inductance of the motor stator, and the mathematical model of the permanent magnet synchronous motor is designed in the stationary coordinate system (α-β):

[0007] S2. Design a sliding mode observer based on the mathematical model of the permanent magnet synchronous motor: Among them, u S =[u α ,u β ] T , is the stator current The budget amount, and are the stator resistance and stator inductance respectively, k is the gain of the sliding mode observer;

[0008] S3, when When e is introduced S =[e α ,e β ] T As the back EMF in the generator magnetic field, As the stator current error, combining step S1 and step S2, we get The state equation is:

[0009] S4, low-pass filter the back electromotive force, and obtain the back electromotive force Among them, z is and The quadratic vector represented by ω represents the mechanical angular velocity of the rotor motor (rad / s). The high-frequency noise signal will cause random vibration of the sliding mode system. This vibration factor will affect the smoothness of the observed value. The sliding surface function is introduced to suppress the interference of the noise signal S: Get the estimated motor speed Motor location where e α and e β is the electromotive force of the permanent magnet synchronous motor;

[0010] S5, using a low-pass filter to compensate for the estimated value of the amplitude position of the back electromotive force that is reduced by the low-pass filter link in step S4; the low-pass filter model is k represents the signal gain of the sliding mode observation model, k>max(||e α ||,||e β ||); is the estimated value of rotor speed;

[0011] S6, according to the electromotive force e α and e β is the magnetic flux φ f and the speed angle ω e The quantity characterized is calculated by the following formula to calculate the value of the rotor speed;

[0012] S7, according to the cutoff frequency ω of the low-pass filter link cutoff , the value of the position where the compensation for phase lag is added is calculated by the following formula;

[0013] in is the estimate of the rotor position;

[0014] S8, respectively, u S ,i s As the budget of stator voltage and current, design sliding mode observer: in, and They are the budgeted amounts of stator resistance Rs and inductance L respectively;

[0015] S9, when and When , the current budget error equation is:

[0016] S10, when the system is in sliding mode, the customized current error e of the synchronous motor S Converges to 0. According to the sliding mode control principle, the sliding mode variable structure control law is obtained as follows:

[0017] S11. Construct the Lyapunov function as:

[0018] S12, according to the saturation function get When the system converges, calculate the synchronous motor rotor position:

[0019] In the above method for detecting the rotor position of a synchronous motor in a pumped storage power plant, in step S2, the gain k of the sliding mode observer is greater than e α and e β The magnitude of the vector.

[0020] In the above method for detecting the rotor position of a synchronous motor in a pumped storage power plant, the error of the stator current in step S3 is in:

[0021] In the aforementioned method for detecting the rotor position of a synchronous motor in a pumped storage power plant, in step S11, no matter what value s takes, the system has:

[0022] Compared with the prior art, the present invention realizes closed-loop control of the synchronous motor system of a pumped-storage power plant by using a sliding mode observer to replace the sensor to estimate the rotor position and speed of the synchronous motor of the pumped-storage power plant. The rotor position information of the synchronous motor of the pumped-storage power plant in the startup phase is obtained by injecting a pulse high-frequency voltage method through the stator voltage and current measured by the motor model, and the improved sliding mode observer is used to estimate the position and speed of the synchronous rotor of the pumped-storage power plant in the medium and high-speed phase with higher accuracy, thereby completing the motor vector control. Compared with the prior art, the present invention has the following advantages:

[0023] (1) Since the technical solution adopted by the present invention adopts a sliding mode observer to replace the sensor to estimate the rotor position and speed of the synchronous motor of the pumped storage power plant, the present invention can make the synchronous motor of the pumped storage power plant simple to assemble, highly reliable and low in cost.

[0024] (2) Because the technical solution adopted by the present invention improves the general sliding mode observer, the present invention can be applied to the synchronous motor of the pumped-storage power plant, eliminate the vibration phenomenon and avoid phase lag, and can estimate the position and speed of the synchronous rotor of the pumped-storage power plant in the medium and high speed stages with higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the structural block diagram of the sliding mode observer of the SPMSM control system of this application;

[0026] Figure 2 It is the block diagram of the position sensorless control of synchronous motor in pumped storage power plant;

[0027] Figure 3 It is the control block diagram of the sliding mode observer of this application;

[0028] Figure 4 It is the experimental waveform of the velocity estimation value and velocity error value of the traditional sliding mode observer;

[0029] Figure 5 It is the experimental waveform of the velocity estimation value and velocity error value of the sliding mode observer improved by the present application;

[0030] Figure 6 This is a comparison chart of the experimental waveforms of the rotor position error values ​​of the general sliding mode observer and the improved sliding mode observer. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0032] Embodiment. A method for detecting the rotor position of a synchronous motor in a pumped storage power plant comprises the following steps: (1) detecting the rotor position of a synchronous motor of a pumped storage power plant according to the electromotive force e of the surface permanent magnet synchronous motor; α and eβ , stator α, β axis current i α 、i β , stator α, β axis voltage u α 、u β , R S is the resistance of the motor stator, L is the inductance of the motor stator, and the mathematical model of the permanent magnet synchronous motor is designed in the stationary coordinate system (α-β):

[0033] (2) According to the motor model in step (1), a sliding mode observer is designed, which can be expressed as: Among them, u S =[u α ,u β ] T , is the stator current The budget amount, and are the stator resistance and stator inductance respectively, k is the gain of the sliding mode observer;

[0034] (3) When When e is introduced S =[e α ,e β ] T As the back EMF in the generator magnetic field, As the stator current error, it is summarized by the formulas in step (1) and step (2): The state equation is:

[0035] (4) Reduce the jitter of the sliding mode system caused by the back EMF due to the noise signal. Process the noise signal, treat the back EMF as a disturbance, perform low-pass filtering, and obtain the back EMF. Among them, z is and The quadratic vector represented by ω represents the mechanical angular velocity of the rotor motor, and S is the sliding surface function that suppresses the interference of noise signals: Get the estimated motor speed Motor location

[0036] (5) A low-pass filter is used to compensate for the estimated value of the amplitude position of the back electromotive force that is reduced in the low-pass filter link. The low-pass filter model is specifically characterized as follows:

[0037] k represents the signal gain of the sliding mode observation model, k>max(||e α ||,||e β ||); is the estimated value of rotor speed;

[0038] (6) According to the electromotive force e α and e β is the magnetic flux φ f and the speed angle ω e The estimated value of the rotor speed is calculated as: where φ f represents the rotor flux (V·S);

[0039] (7) According to the cutoff frequency ω of the low-pass filter cutoff , the estimated value for the position to add compensation for phase lag is calculated as:

[0040] (8) respectively S ,i s As the budget of stator voltage and current, design sliding mode observer: in, and They are the budgeted amounts of stator resistance Rs and inductance L respectively;

[0041] (9) When and When , the current budget error equation is:

[0042]

[0043] (10) When the system is in sliding mode, the customized current error e of the synchronous motor S Converges to 0. According to the sliding mode control principle, the sliding mode variable structure control law is obtained as follows:

[0044]

[0045] (11) Construct the Lyapunov function as: Conduct stability analysis on the system;

[0046] (12) According to the saturation function get When the system converges, calculate the synchronous motor rotor position:

[0047] The gain k of the sliding mode observer in step (2) must be greater than e α and e β The magnitude of the vector.

[0048] The error of stator current in step (3) in:

[0049] In step (11), no matter what value s takes, the system has:

[0050] The present invention can compensate for the phase delay of the sliding mode observer itself and obtain the rotor position information of the synchronous motor of the pumped-storage power plant during the startup phase. Moreover, the present invention can eliminate the chattering phenomenon and avoid phase lag through the improved sliding mode observer, and estimate the rotor position and speed of the synchronous motor of the pumped-storage power plant in the medium and high speed phase with higher accuracy.

Claims

1. A method for detecting the rotor position of a synchronous motor in a pumped storage power plant, characterized in that: The following steps are involved: S1, according to the electromotive force e of the surface permanent magnet synchronous motor α and e β , stator α, β axis current i α 、i β , stator α, β axis voltage u α 、u β , R S is the resistance of the motor stator, L is the inductance of the motor stator, and the mathematical model of the permanent magnet synchronous motor is designed in the stationary coordinate system (α-β): S2. Design a sliding mode observer based on the mathematical model of the permanent magnet synchronous motor: Among them, u S =[u α ,u β ] T , is the stator current The budget amount, and are the stator resistance and stator inductance respectively, k is the gain of the sliding mode observer; S3, when When e is introduced S =[e α ,e β ] T As the back EMF in the generator magnetic field, As the stator current error, combining step S1 and step S2, we get The state equation is: S4, low-pass filter the back electromotive force, and obtain the back electromotive force Among them, z is and The quadratic vector represented by ω represents the mechanical angular velocity of the rotor motor, and S is the sliding surface function that suppresses the interference of noise signals: Get the estimated motor speed Motor location S5, using a low-pass filter to compensate for the estimated value of the amplitude position of the back electromotive force that is reduced by the low-pass filter link in step S4; the low-pass filter model is k represents the signal gain of the sliding mode observation model, k>max(||e α ||,||e β ||); is the estimated value of rotor speed; S6, according to the electromotive force e α and e β is the magnetic flux φ f and the speed angle ω e The quantity characterized is calculated by the following formula to calculate the value of the rotor speed; S7, according to the cutoff frequency ω of the low-pass filter link cutoff , the value of the position where the compensation for phase lag is added is calculated by the following formula; S8, respectively, u S ,i s As the budget of stator voltage and current, design sliding mode observer: in, and They are the budgeted amounts of stator resistance Rs and inductance L respectively; S9, when and When , the current budget error equation is: S10, when the system is in sliding mode, the customized current error e of the synchronous motor S Converges to 0. According to the sliding mode control principle, the sliding mode variable structure control law is obtained as follows: S11. Construct the Lyapunov function as: S12, according to the saturation function get When the system converges, calculate the synchronous motor rotor position:

2. A method for detecting the rotor position of a synchronous motor in a pumped storage power plant according to claim 1, characterized in that: In step S2, the gain k of the sliding mode observer must be greater than e α and e β The magnitude of the vector.

3. A method for detecting the rotor position of a synchronous motor in a pumped storage power plant according to claim 1, characterized in that: The error of stator current in step S3 in:

4. A method for detecting the rotor position of a synchronous motor in a pumped storage power plant according to claim 1, characterized in that: In step S11, no matter what value s takes, the system has:

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