Method for Determining Sensorless Doubled-Frequency Rotational Speed and Phase of Permanent Magnet Synchronous Generator Converter

Abstract

The present invention discloses a sensorless multiplier speed and phase determination method for a permanent magnet synchronous generator converter, comprising the following steps: A: calculating the actual voltage of the generator in a two-phase stationary coordinate system within each sampling period; B: calculating the phase increment of the current sampling period; C: performing phase multiplication on the phase increment to obtain a new phase waveform; D: calculating an estimated frequency of the generator within the current sampling period based on the value of an external pulse counter within the 0 to 1 period in the new phase waveform; and E: calculating the actual frequency of the generator using a PID controller, and then calculating the actual speed and phase within the current sampling period based on the actual frequency. This method can more quickly and accurately determine the converter's speed and phase, thereby providing support for precise converter control.

Description

Technical Field

[0001] The present invention belongs to the technical field of control of three-phase converters of permanent magnet synchronous wind turbines, and specifically relates to a method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter. The method is specifically aimed at determining the speed and phase under speed sensorless working conditions. Background Art

[0002] A wind turbine is a device that converts wind energy into electricity. It primarily consists of blades, a generator, mechanical components, and electrical components. Wind power generation utilizes wind power to rotate the blades, which in turn generates electricity. Because wind power requires no fuel and produces no radiation or air pollution, it is rapidly gaining popularity worldwide.

[0003] Currently, China has strict requirements for the performance indicators and power generation quality of wind power converters. In particular, the real-time and accurate speed and phase are extremely important for converter control and performance. In permanent magnet synchronous wind turbine systems, when the generator speed is low, without a speed sensor, the generator speed can only be calculated using back-electromotive force. However, this results in a certain time delay in the calculated generator speed, which lacks real-time performance. The generator phase can only be calculated using the phase difference, but the calculated result fluctuates significantly. To reduce this fluctuation, filtering is required, but filtering also affects real-time performance. Therefore, it is necessary to develop new technologies to improve the technical problems existing in existing technologies. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned technical problems existing in the prior art and provide a method for determining the sensorless frequency-multiplied speed and phase of a permanent magnet synchronous generator converter. This method can obtain the speed and phase of the converter more quickly and accurately, thereby providing support for the precise control of the converter.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter is characterized in that the method is based on the determination of the speed and phase without a speed sensor and comprises the following steps:

[0007] Step A: Set the sampling period. First, collect the three-phase voltage and three-phase current of the generator according to the sampling period interval. Then, calculate the calibrated three-phase voltage and three-phase current through zero-drift adaptive calculation. Then, calculate the actual voltage of the generator in the two-phase stationary coordinate system within each sampling period based on the calibrated three-phase voltage and three-phase current.

[0008] Step B: obtaining the per-unit estimated value of the phase angle of the generator in each sampling period according to the result of step A, and calculating the phase increment of the current sampling period according to the per-unit estimated value of the phase angle of the generator;

[0009] Step C: perform phase multiplication on the result of step B, so that the phase increment returns to zero when it accumulates to 1, and obtain a new phase waveform;

[0010] Step D: In the new phase waveform, a virtual pulse counter is preset to record the value of the external pulse counter in the period 0 to 1, and the estimated value of the generator frequency in the current sampling period is calculated based on the recorded value;

[0011] Step E: Integrate the actual voltage of the generator in the two-phase stationary coordinate system, convert the integral value to the two-phase rotating coordinate system and calculate the change of the D-axis relative to the sum of the D-axis and Q-axis moduli. Then, the PID controller calculates the actual frequency of the generator based on the frequency estimation value and the change, and calculates the actual speed and actual phase in the current sampling period based on the actual frequency.

[0012] In step A, the actual voltage is calculated as follows: first, the three-phase voltage and three-phase current collected each time are zero-drift adaptively calculated to obtain the calibrated three-phase voltage and three-phase current, and then the calibrated three-phase voltage and three-phase current are converted into the instantaneous voltage vector and instantaneous current vector in the two-phase stationary coordinate system, and then the actual voltage of the generator in the two-phase stationary coordinate system is calculated based on the instantaneous voltage vector and instantaneous current vector.

[0013] In step A, the collected three-phase voltages are set to The three-phase currents are After zero drift adaptation, the calibrated three-phase voltage and three-phase current are:

[0014]

[0015] Where U1(t), U2(t), and U3(t) are the calibrated three-phase voltages, and I1(t), I2(t), and I3(t) are the calibrated three-phase currents.

[0016] In step A, the actual voltage of the generator in the two-phase stationary coordinate system is calculated as follows:

[0017]

[0018] Among them, the conversion relationship between the calibrated three-phase voltage and the instantaneous voltage vector in the two-phase stationary coordinate system is:

[0019]

[0020] The conversion relationship between the calibrated three-phase current and the instantaneous current vector in the two-phase stationary coordinate system is:

[0021]

[0022] Where U α (t) and U β (t) are the actual voltages of the generator in the two-phase stationary coordinate system, L is the generator winding inductive reactance, R is the generator impedance, and t is time; and They are the instantaneous voltage vector, I α (t) and I β (t) are instantaneous current vectors respectively.

[0023] In step B, the phase increment of the current sampling period is calculated by first performing an inverse tangent on the actual voltage of the generator in the two-phase stationary coordinate system to obtain the phase angle, then performing per-unit normalization on the phase angle from 0 to 1 to obtain a per-unit estimated phase angle, and then calculating the phase increment of the current sampling period based on the per-unit estimated phase angle of the previous sampling period and the per-unit estimated phase angle of the current sampling period. The calculation formula is:

[0024]

[0025] Where, is the per-unit estimated value of the phase angle of the previous sampling period, θ0 is the per-unit estimated value of the phase angle of the current sampling period, and dθ is the phase increment of the current sampling period.

[0026] In step C, phase doubling refers to amplifying the multiple of the phase increment.

[0027] In step D, the frequency estimate is calculated as follows:

[0028]

[0029] in,

[0030] T 0 =Δt×N sum

[0031] N sum =N+N -1 +N -2 ...+N -m

[0032] Where, f 0 is the estimated frequency of the generator, T 0 is the estimated value of the generator's rotation period, N is the value recorded by the virtual pulse counter, N sum is the sum of the values recorded by the virtual pulse counter, N -1is the value recorded by the virtual pulse counter last time, N -2 N is the value last recorded on the virtual pulse counter. -m is the value recorded by the virtual pulse counter m times before, m is the magnification factor, and Δt is the sampling period.

[0033] In step E, the actual frequency of the generator is calculated by using the frequency estimate as the base value of the PID controller, 0 as the reference, and the change in the D-axis relative to the sum of the D-axis and Q-axis moduli as feedback. The voltage change is calculated as follows:

[0034] U 变 =U d (t) / (|U d (t)|+|U q (t)|)

[0035]

[0036] Where U 变 is the change in the D-axis modulus relative to the sum of the D-axis and Q-axis moduli, and is the integral value obtained by integrating the actual voltage of the generator in the two-phase stationary coordinate system, U d (t) and U q (t) are the integral values and Convert the voltage to the two-phase rotating coordinate system.

[0037] In step E, the actual speed and actual phase are calculated as follows:

[0038]

[0039] θ=θ -1 +f×Δt

[0040] Where ω is the actual speed of the current sampling period, θ is the actual phase of the current sampling period, P is the number of pole pairs, f is the actual frequency, and θ is the actual speed of the current sampling period. -1 is the actual phase of the previous sampling period and returns to zero when θ>1.

[0041] By adopting the above technical solution, the beneficial technical effects of the present invention are:

[0042] The present invention utilizes a zero-drift adaptive method to determine speed and phase, effectively reducing the impact of temperature on data sampling and achieving three-phase voltage and current balance. Subsequent calculations are performed in a two-phase stationary (α, β) coordinate system. By converting three sets of voltage and current data into two sets of current and voltage data, followed by data filtering and related calculations, the computational effort is reduced by one-third. Phase multiplication offers the advantage of obtaining a fixed-multiple high-frequency phase change, converting low-frequency operations into high-frequency operations, and improving real-time performance. By calculating the integral value of the generator voltage in a two-phase stationary coordinate system, data filtering and noise reduction can be achieved, facilitating subsequent power calculations. The voltage integral value is then converted to a two-phase rotating (D, Q) coordinate system, and the generator speed and phase are calculated using a phase-locked loop (PLL). This allows for faster and more accurate determination of the converter speed and phase compared to existing technologies. This provides a more real-time generator phase angle for subsequent current loop control calculations and provides strong support for precise converter control. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Flowchart of the present invention.

[0044] Figure 2 Schematic diagram of the three-phase to two-phase stationary coordinate system.

[0045] Figure 3 Schematic diagram of converting a two-phase stationary coordinate system to a two-phase rotating coordinate system. DETAILED DESCRIPTION

[0046] Example 1

[0047] This embodiment discloses a method for determining the speed and phase of a permanent magnet synchronous generator converter without a sensor. The method is based on the determination of the speed and phase without a speed sensor. Figure 1 As shown, it includes the following steps:

[0048] Step A: Set the sampling period, which generally does not exceed 0.5ms and is determined based on actual needs. After the sampling period is set, the three-phase voltage and three-phase current of the generator are collected at intervals according to the sampling period. The calibrated three-phase voltage and three-phase current are then calculated through zero-drift adaptive calculation. The actual voltage of the generator in the two-phase stationary coordinate system is calculated based on the calibrated three-phase voltage and three-phase current during each sampling period.

[0049] Among them, the calculation method of the actual voltage is: first, the three-phase voltage and three-phase current collected each time are zero-drift adaptively calculated to obtain the calibrated three-phase voltage and three-phase current, and then the calibrated three-phase voltage and three-phase current are converted into the instantaneous voltage vector and instantaneous current vector in the two-phase stationary coordinate system, and then the actual voltage of the generator in the two-phase stationary coordinate system is calculated based on the instantaneous voltage vector and instantaneous current vector.

[0050] Furthermore, the specific implementation method of this step is: set the collected three-phase voltages to be The three-phase currents are After zero drift adaptation, the calibrated three-phase voltage and three-phase current are:

[0051]

[0052] Where U1(t), U2(t), and U3(t) are the calibrated three-phase voltages, and I1(t), I2(t), and I3(t) are the calibrated three-phase currents.

[0053] Furthermore, the calculation method of the actual voltage of the generator in the two-phase stationary coordinate system is:

[0054]

[0055]

[0056] Among them, Figure 2 As shown,

[0057] The conversion relationship between the calibrated three-phase voltage and the instantaneous voltage vector in the two-phase stationary coordinate system is:

[0058]

[0059] The conversion relationship between the calibrated three-phase current and the instantaneous current vector in the two-phase stationary coordinate system is:

[0060]

[0061] Where U α (t) and U β (t) are the actual voltages of the generator in the two-phase stationary coordinate system, L is the generator winding inductive reactance, R is the generator impedance, and t is time; and They are the instantaneous voltage vector, I α (t) and I β (t) are instantaneous current vectors respectively.

[0062] Step B: Obtain the per-unit estimated value of the phase angle of the generator in each sampling period according to the result of step A, and calculate the phase increment of the current sampling period according to the per-unit estimated value of the phase angle of the generator.

[0063] The phase increment of the current sampling period is calculated as follows: first, the actual voltage of the generator in the two-phase stationary coordinate system is arc tangented to obtain the phase angle, then the phase angle is normalized from 0 to 1 to obtain a per-unit estimated phase angle, and then the phase increment of the current sampling period is calculated based on the per-unit estimated phase angle of the previous sampling period and the per-unit estimated phase angle of the current sampling period. The calculation formula is:

[0064]

[0065] Where, is the per-unit estimated value of the phase angle of the previous sampling period, θ0 is the per-unit estimated value of the phase angle of the current sampling period, and dθ is the phase increment of the current sampling period.

[0066] Step C: Perform phase multiplication on the result of step B, so that the phase increment returns to zero when it accumulates to 1, and obtain a new phase waveform. Phase multiplication refers to the multiple by which the phase increment is amplified. The number of amplification bits can usually be determined according to actual needs, such as 32 times, 64 times, 128 times, etc.

[0067] Step D: In the new phase waveform, a virtual pulse counter is preset to record the value of the external pulse counter in the period 0 to 1, and the frequency estimation value of the generator in the current sampling period is calculated based on the recorded value.

[0068] The frequency estimate is calculated as:

[0069]

[0070] in,

[0071] T 0 =Δt×N sum

[0072] N sum =N+N -1 +N -2 ...+N -m

[0073] Where, f 0 is the estimated frequency of the generator, T 0 is the estimated value of the generator's rotation period, N is the value recorded by the virtual pulse counter, N sum is the sum of the values recorded by the virtual pulse counter, N -1 is the value recorded by the virtual pulse counter last time, N -2N is the value last recorded on the virtual pulse counter. -m is the value recorded by the virtual pulse counter m times before, m is the magnification factor, and Δt is the sampling period.

[0074] Step E: Integrate the actual generator voltage in the two-phase stationary coordinate system, convert the integral value to the two-phase rotating coordinate system, and calculate the change in the D-axis relative to the sum of the D-axis and Q-axis moduli. The PID controller then calculates the actual generator frequency based on the frequency estimate and the change. The actual speed and phase for the current sampling period are calculated based on the actual frequency. Repeat these steps to obtain the actual speed and phase for other sampling periods.

[0075] The actual frequency of the generator is calculated by using the frequency estimate as the base value of the PID controller, 0 as the reference, and the relative change in the D-axis voltage as feedback. The actual frequency of the generator is calculated by the PID controller. The voltage change is calculated as follows:

[0076] U 变 =U d (t) / (|U d (t)|+|U q (t)|)

[0077]

[0078] Where U 变 is the change in the D-axis modulus relative to the sum of the D-axis and Q-axis moduli, and is the integral value obtained by integrating the actual voltage of the generator in the two-phase stationary coordinate system, U d (t) and U q (t) are the integral values and Converted to the voltage in the two-phase rotating coordinate system, the conversion relationship is as follows Figure 3 shown.

[0079] Furthermore, the actual speed and actual phase are calculated as follows:

[0080]

[0081] θ=θ -1 +f×Δt

[0082] Where ω is the actual speed of the current sampling period, θ is the actual phase of the current sampling period, P is the number of pole pairs, f is the actual frequency, and θ is the actual speed of the current sampling period. -1 is the actual phase of the previous sampling period and returns to zero when θ>1.

[0083] Example 2

[0084] This example verifies the method described in Example 1 as follows:

[0085] Assuming the rated speed of the generator is 8.4 Hz, the sampling period is 0.5 ms, and the phase multiplication frequency is 32 times, the verification method is as follows:

[0086] Step 1: After the three-phase voltage sampling is calibrated by zero drift adaptive calibration, the three-phase voltages U1(t), U2(t) and U3(t) are mixed waveform data of sine waves and switching waves that vary with time. After the three-phase current sampling is calibrated by zero drift adaptive calibration, the currents I1(t), I2(t) and I3(t) are quasi-sine wave data that vary with time. The calibrated three-phase voltage and three-phase current are converted from three-phase to two-phase stationary (α, β) coordinate systems, and the instantaneous voltage vector is obtained. and It is a mixed waveform data of sine wave and switching wave that changes with time. The instantaneous current vector I α (t) and I β (t) is the sine wave-like data that changes with time.

[0087] Calculate the actual voltage of the generator from three-phase to two-phase static (α, β) coordinate system U according to the back electromotive force α (t) and U β (t), where the generator inductive reactance and impedance are constants, U α (t) and U β (t) is the sine wave-like data that changes with time.

[0088]

[0089] Step 2: Calculate the generator phase angle at this moment It is triangular wave data with an amplitude ranging from 0 to 1 that changes over time.

[0090] Calculate the phase angle increment dθ=θ0(0)-θ0(-1), where θ0(0) is the generator phase angle of the current sampling period, and θ0(-1) is the generator phase angle of the previous sampling period.

[0091] The phase increment is multiplied by 32×dθ, and the accumulated value is 32×dθ. When it exceeds 1, it returns to zero, and the phase angle θ of 32 times the frequency is obtained. 32 (t) is a triangular wave-like data with an amplitude ranging from 0 to 1 that varies with time, and a frequency of approximately 32 times the generator frequency.

[0092] Calculate θ by external timing pulse variable 32 (t) The period of a triangle wave T 32 , magnified 32 times, to obtain the estimated value of the generator's rotation period T 0, the estimated frequency value

[0093] Calculate the actual voltage U in the two-phase stationary coordinate system α (t) and the integral value of U β (t) and

[0094]

[0095] is the integral value of the previous sampling period, and U α (0) is the value of U α (t) in this sampling period

[0096] The calculation is the same

[0097] By transforming from the two-phase stationary coordinate system to the two-phase rotating coordinate system, calculate U d (t) and U q (t)

[0098] The feedforward of the phase-locked loop PID is the estimated frequency value f0, the reference value is 0, and the feedback value is U d (t) and U q (t) in which the variable of U d (t), and the actual frequency f of the generator is obtained

[0099] Comparison method: If there is no frequency doubling, by calculating the period T0' of a triangular wave of θ0(t), the estimated frequency value f0' of the generator is obtained, and then through the same phase-locked loop PID, the actual frequency f' of the generator is obtained

[0100] Through the above comparison test, it can be seen that when the speed of the generator changes step by step, f' is more than half of the current real period of the generator later than f, which also proves that the present invention can obtain the speed and phase of the converter faster and more accurately by adopting the above specific steps

[0101] The above is only the specific implementation manner of the present invention. Any feature disclosed in this specification, unless specifically described, can be replaced by other equivalent or similar-purpose alternative features; all the features disclosed, or all the steps in all the methods or processes, except for the mutually exclusive features and / or steps, can be combined in any way

Claims

1. A method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter, characterized by: The method is based on the determination of speed and phase without a speed sensor, and includes the following steps: Step A: Set the sampling period. First, collect the three-phase voltage and three-phase current of the generator according to the sampling period interval. Then, calculate the calibrated three-phase voltage and three-phase current through zero-drift adaptive calculation. Then, calculate the actual voltage of the generator in the two-phase stationary coordinate system within each sampling period based on the calibrated three-phase voltage and three-phase current. Step B: obtaining the per-unit estimated value of the phase angle of the generator in each sampling period according to the result of step A, and calculating the phase increment of the current sampling period according to the per-unit estimated value of the phase angle of the generator; Step C: perform phase multiplication on the result of step B, so that the phase increment returns to zero when it accumulates to 1, and obtain a new phase waveform; Step D: In the new phase waveform, a virtual pulse counter is preset to record the value of the external pulse counter in the period 0 to 1, and the estimated value of the generator frequency in the current sampling period is calculated based on the recorded value; Step E: Integrate the actual voltage of the generator in the two-phase stationary coordinate system, convert the integral value to the two-phase rotating coordinate system and calculate the change of the D-axis relative to the sum of the D-axis and Q-axis moduli. Then, the PID controller calculates the actual frequency of the generator based on the frequency estimation value and the change, and calculates the actual speed and actual phase in the current sampling period based on the actual frequency.

2. The method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter according to claim 1, characterized in that: In step A, the actual voltage is calculated as follows: first, the three-phase voltage and three-phase current collected each time are zero-drift adaptively calculated to obtain the calibrated three-phase voltage and three-phase current, and then the calibrated three-phase voltage and three-phase current are converted into the instantaneous voltage vector and instantaneous current vector in the two-phase stationary coordinate system, and then the actual voltage of the generator in the two-phase stationary coordinate system is calculated based on the instantaneous voltage vector and instantaneous current vector.

3. The method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter according to claim 2, characterized in that: In step A, the collected three-phase voltages are set to The three-phase currents are After zero drift adaptation, the calibrated three-phase voltage and three-phase current are: Where U1(t), U2(t), and U3(t) are the calibrated three-phase voltages, and I1(t), I2(t), and I3(t) are the calibrated three-phase currents.

4. The method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter according to claim 3, characterized in that: In step A, the actual voltage of the generator in the two-phase stationary coordinate system is calculated as follows: Among them, the conversion relationship between the calibrated three-phase voltage and the instantaneous voltage vector in the two-phase stationary coordinate system is: The conversion relationship between the calibrated three-phase current and the instantaneous current vector in the two-phase stationary coordinate system is: Where U α (t) and U β (t) are the actual voltages of the generator in the two-phase stationary coordinate system, L is the generator winding inductive reactance, R is the generator impedance, and t is time; and They are the instantaneous voltage vector, I α (t) and I β (t) are instantaneous current vectors respectively.

5. The method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter according to any one of claims 1 to 4, characterized in that: In step B, the phase increment of the current sampling period is calculated by first performing an inverse tangent on the actual voltage of the generator in the two-phase stationary coordinate system to obtain the phase angle, then performing per-unit normalization on the phase angle from 0 to 1 to obtain a per-unit estimated phase angle, and then calculating the phase increment of the current sampling period based on the per-unit estimated phase angle of the previous sampling period and the per-unit estimated phase angle of the current sampling period. The calculation formula is: Where, is the per-unit estimated value of the phase angle of the previous sampling period, θ0 is the per-unit estimated value of the phase angle of the current sampling period, and dθ is the phase increment of the current sampling period.

6. The method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter according to claim 1, characterized in that: In step C, phase doubling refers to amplifying the multiple of the phase increment.

7. The method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter according to claim 5, characterized in that: In step D, the frequency estimate is calculated as follows: in, T 0 =Δt×N sum N sum =N+N -1 +N -2 ...+N -m Where, f 0 is the estimated frequency of the generator, T 0 is the estimated value of the generator's rotation period, N is the value recorded by the virtual pulse counter, N sum is the sum of the values recorded by the virtual pulse counter, N -1 is the value recorded by the virtual pulse counter last time, N -2 N is the value last recorded on the virtual pulse counter. -m is the value recorded by the virtual pulse counter m times before, m is the magnification factor, and Δt is the sampling period.

8. The method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter according to claim 7, characterized in that: In step E, the actual frequency of the generator is calculated by using the frequency estimate as the base value of the PID controller, 0 as the reference, and the change in the D-axis relative to the sum of the D-axis and Q-axis moduli as feedback. The voltage change is calculated as follows: U 变 =U d (t) / (|U d (t)|+|U q (t)|) Where U 变 is the change in the D-axis modulus relative to the sum of the D-axis and Q-axis moduli, and is the integral value obtained by integrating the actual voltage of the generator in the two-phase stationary coordinate system, U d (t) and U q (t) are the integral values and Converted to the voltage in the two-phase rotating coordinate system, θ is the actual phase of the current sampling period.

9. The method for determining the sensorless multiplier speed and phase of a permanent magnet synchronous generator converter according to claim 8, characterized in that: In step E, the actual speed and actual phase are calculated as follows: θ=θ -1 +f×Δt Where ω is the actual speed of the current sampling period, θ is the actual phase of the current sampling period, P is the number of pole pairs, f is the actual frequency, and θ is the actual speed of the current sampling period. -1 is the actual phase of the previous sampling period and returns to zero when θ>1.

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