A method and device for suppressing torque and reactive power fluctuations of variable frequency transformer

Abstract

The present invention discloses a method and device for suppressing torque and reactive power fluctuations of a variable frequency transformer. The control method maintains the DC bus voltage stability through a parallel three-phase converter, and solves the problems of unbalanced grid voltage and harmonic distortion on both sides through two series three-phase converters, which can completely suppress the torque and reactive power fluctuations of the variable frequency transformer caused by the negative sequence component and harmonic component in the unbalanced and harmonically distorted grid voltage. At the same time, since the number of second-order filters used is greatly reduced, it is beneficial to improve the response speed and stability of the control system.

Description

Technical Field

[0001] The present invention relates to the technical field of asynchronous interconnection of power grids, and in particular to a method and device for suppressing torque and reactive power fluctuations of a variable frequency transformer. Background Art

[0002] When the grid voltage on both sides of the variable frequency transformer is unbalanced and harmonically distorted, the current flowing through the variable frequency transformer will be unbalanced and harmonically distorted, which will cause the torque and reactive power of the variable frequency transformer to fluctuate at twice the rotor rotation electrical angular velocity, six times the rotor rotation electrical angular velocity, twice the stator synchronous angular velocity, twice the rotor synchronous angular velocity, six times the stator synchronous angular velocity minus twice the rotor synchronous angular velocity, four times the stator synchronous angular velocity, six times the rotor synchronous angular velocity minus twice the stator synchronous angular velocity, six times the stator synchronous angular velocity, six times the rotor synchronous angular velocity, eight times the stator synchronous angular velocity, six times the stator synchronous angular velocity plus twice the rotor synchronous angular velocity, two times the stator synchronous angular velocity plus six times the rotor synchronous angular velocity, twelve times the stator synchronous angular velocity, and six times the stator synchronous angular velocity plus six times the rotor synchronous angular velocity. The fluctuation of torque will reduce the mechanical life of the shaft, and the fluctuation of reactive power will affect the stability of the power system.

[0003] The existing technology cannot completely suppress the torque and reactive power fluctuations of the variable frequency transformer caused by the unbalanced grid voltage and harmonic distortion while achieving the ride-through control of the variable frequency transformer. Summary of the invention

[0004] The present invention provides a method and device for suppressing torque and reactive power fluctuations of a variable frequency transformer, which are used to maintain the stability of the DC bus voltage through a parallel three-phase converter, and solve the problems of unbalanced grid voltage and harmonic distortion on both sides through two series three-phase converters, thereby completely suppressing the torque and reactive power fluctuations of the variable frequency transformer caused by the negative sequence components and harmonic components in the unbalanced and harmonically distorted grid voltage.

[0005] In a first aspect, a variable frequency transformer torque and reactive power fluctuation suppression method provided by an embodiment of the present invention is applied to a control system, a stator-side series three-phase converter, and a rotor-side series three-phase converter;

[0006] The variable calculation method applied to the control system includes:

[0007] Obtain the stator side grid voltage, stator voltage, rotor side grid voltage, rotor voltage, stator current, rotor current, pole pair number and excitation inductance;

[0008] Based on the stator-side grid voltage, the stator voltage, the rotor-side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, a stator-side grid phase angle, a rotor-side grid phase angle, a stator-side grid positive-sequence voltage DC component, a stator positive-sequence voltage DC component, a rotor-side grid positive-sequence voltage DC component, a rotor positive-sequence voltage DC component, a stator positive-sequence current DC component, a rotor positive-sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power twice rotor frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component and a stator reactive power six times rotor frequency fluctuation component are obtained;

[0009] The control method applied to the stator-side series three-phase converter comprises:

[0010] Based on the phase angle of the stator-side power grid, the DC component of the stator-side power grid positive-sequence voltage, the DC component of the stator positive-sequence voltage, the DC component of the stator positive-sequence current, the electromagnetic torque twice the stator frequency fluctuation component, the electromagnetic torque six times the stator frequency fluctuation component, the stator reactive power twice the stator frequency fluctuation component, and the stator reactive power six times the stator frequency fluctuation component, in combination with a first preset voltage control calculation formula, a DC component of a positive-sequence voltage reference value of a stator-side series three-phase converter, a DC component of a negative-sequence voltage reference value of a stator-side series three-phase converter, a DC component of a fifth harmonic voltage reference value of a stator-side series three-phase converter, and a DC component of a seventh harmonic voltage reference value of a stator-side series three-phase converter are calculated;

[0011] Determine the voltage reference value of the stator side series three-phase converter in a two-phase stator stationary coordinate system according to the DC component of the positive sequence voltage reference value of the stator side series three-phase converter, the DC component of the negative sequence voltage reference value of the stator side series three-phase converter, the DC component of the fifth harmonic voltage reference value of the stator side series three-phase converter, and the DC component of the seventh harmonic voltage reference value of the stator side series three-phase converter;

[0012] By performing space vector modulation on the voltage reference value of the stator-side series three-phase converter, a control signal of the stator-side series three-phase converter switch is obtained; the control signal of the stator-side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced voltage and harmonic distortion of the stator-side power grid;

[0013] The control method applied to the rotor-side series three-phase converter comprises:

[0014] Based on the rotor-side grid phase angle, the rotor-side grid positive-sequence voltage DC component, the rotor positive-sequence voltage DC component, the electromagnetic torque twice the rotor frequency fluctuation component, the electromagnetic torque six times the rotor frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component, in combination with a second preset voltage control calculation formula, a rotor-side series three-phase converter positive-sequence voltage reference value DC component, a rotor-side series three-phase converter negative-sequence voltage reference value DC component, a rotor-side series three-phase converter fifth harmonic voltage reference value DC component and a rotor-side series three-phase converter seventh harmonic voltage reference value DC component are calculated;

[0015] Determine the voltage reference value of the rotor side series three-phase converter in a two-phase rotor rotating coordinate system according to the DC component of the positive sequence voltage reference value of the rotor side series three-phase converter, the DC component of the negative sequence voltage reference value of the rotor side series three-phase converter, the DC component of the fifth harmonic voltage reference value of the rotor side series three-phase converter, and the DC component of the seventh harmonic voltage reference value of the rotor side series three-phase converter;

[0016] By performing space vector modulation on the voltage reference value of the three-phase converter in series on the rotor side, a control signal of the three-phase converter switch in series on the rotor side is obtained; the control signal of the three-phase converter switch in series on the rotor side is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced voltage and harmonic distortion of the rotor side grid.

[0017] Optionally, based on the stator-side grid voltage, the stator voltage, the rotor-side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, a stator-side grid phase angle, a rotor-side grid phase angle, a stator-side grid positive-sequence voltage DC component, a stator positive-sequence voltage DC component, a rotor-side grid positive-sequence voltage DC component, a rotor positive-sequence voltage DC component, a stator positive-sequence current DC component, a rotor positive-sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power twice rotor frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component and a stator reactive power six times rotor frequency fluctuation component are obtained, including:

[0018] The stator side grid voltage and the rotor side grid voltage are processed respectively by a digital phase-locked loop to obtain the stator side grid phase angle and the rotor side grid phase angle;

[0019] Based on the stator side grid phase angle and the rotor side grid phase angle, coordinate transformation is performed on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current and the rotor current to obtain the stator side grid positive sequence voltage DC component, the stator positive sequence voltage DC component, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the stator positive sequence current DC component and the rotor positive sequence current DC component.

[0020] Optionally, based on the stator-side grid voltage, the stator voltage, the rotor-side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, a stator-side grid phase angle, a rotor-side grid phase angle, a stator-side grid positive-sequence voltage DC component, a stator positive-sequence voltage DC component, a rotor-side grid positive-sequence voltage DC component, a rotor positive-sequence voltage DC component, a stator positive-sequence current DC component, a rotor positive-sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power twice rotor frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component and a stator reactive power six times rotor frequency fluctuation component are obtained, and further comprising:

[0021] Based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance, the electromagnetic torque twice stator frequency fluctuation component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times stator frequency fluctuation component and the electromagnetic torque six times rotor frequency fluctuation component are obtained;

[0022] Based on the stator positive-sequence voltage DC component and the stator positive-sequence current DC component, the stator reactive power twice the stator frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, the stator reactive power six times the stator frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component are obtained.

[0023] Optionally, based on the stator-side grid phase angle and the rotor-side grid phase angle, coordinate transformation is performed on the stator-side grid voltage, the stator voltage, the rotor-side grid voltage, the rotor voltage, the stator current, and the rotor current to obtain the stator-side grid positive-sequence voltage DC component, the stator positive-sequence voltage DC component, the rotor-side grid positive-sequence voltage DC component, the rotor positive-sequence voltage DC component, the stator positive-sequence current DC component, and the rotor positive-sequence current DC component, including:

[0024] Based on the phase angle of the stator-side power grid, the stator voltage and the stator current are transformed from three-phase static to two-phase rotating coordinates to obtain the stator-side power grid positive-sequence voltage DC component, the stator positive-sequence voltage DC component and the stator positive-sequence current DC component;

[0025] Based on the rotor-side grid phase angle, the rotor-side grid voltage, the rotor voltage and the rotor current are transformed from three-phase static to two-phase rotating coordinates to obtain the rotor-side grid positive-sequence voltage DC component, the rotor positive-sequence voltage DC component and the rotor positive-sequence current DC component.

[0026] Optionally, based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance, obtaining the electromagnetic torque twice stator frequency fluctuation component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times stator frequency fluctuation component and the electromagnetic torque six times rotor frequency fluctuation component includes:

[0027] The electromagnetic torque is calculated based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance in combination with an electromagnetic torque calculation formula;

[0028] Based on the electromagnetic torque, a double stator frequency fluctuation component of the electromagnetic torque is obtained by passing it through a bandpass filter of a first preset center frequency;

[0029] Based on the electromagnetic torque, a double rotor frequency fluctuation component of the electromagnetic torque is obtained through a bandpass filter of a second preset center frequency;

[0030] Based on the electromagnetic torque, a six-fold stator frequency fluctuation component of the electromagnetic torque is obtained by passing it through a bandpass filter of a third preset center frequency;

[0031] Based on the electromagnetic torque, a six-fold rotor frequency fluctuation component of the electromagnetic torque is obtained through a bandpass filter with a fourth preset center frequency.

[0032] Optionally, based on the stator positive sequence voltage DC component and the stator positive sequence current DC component, the stator reactive power twice the stator frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, the stator reactive power six times the stator frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component are obtained, including:

[0033] Based on the stator positive sequence voltage DC component and the stator positive sequence current DC component, combined with the reactive power calculation formula, the stator reactive power is calculated;

[0034] Based on the stator reactive power, a stator reactive power fluctuation component of twice the stator frequency is obtained by passing the stator reactive power through a bandpass filter of the first preset center frequency;

[0035] Based on the stator reactive power, a twice rotor frequency fluctuation component of the stator reactive power is obtained through a bandpass filter of the second preset center frequency;

[0036] Based on the stator reactive power, a six-fold stator frequency fluctuation component of the stator reactive power is obtained through a bandpass filter of the third preset center frequency;

[0037] Based on the stator reactive power, the stator reactive power six times rotor frequency fluctuation component is obtained through the bandpass filter of the fourth preset center frequency.

[0038] Optionally, the electromagnetic torque calculation formula is specifically:

[0039]

[0040] Among them, T e is the electromagnetic torque, p n is the pole pair number, L m is the magnetizing inductance, and are the d-axis component and q-axis component of the stator positive sequence current respectively, and They are the d-axis component and q-axis component of the rotor positive sequence current respectively;

[0041] The reactive power calculation formula is specifically:

[0042]

[0043] Among them, Q s is the stator reactive power, and They are the d-axis component and q-axis component of the stator positive sequence voltage respectively.

[0044] Optionally, the first preset voltage control calculation formula is:

[0045]

[0046] Where s is the Laplace operator, and are the d-axis component and q-axis component of the positive sequence voltage reference value of the three-phase converter in series on the stator side, and are the reference value and actual value of the stator positive sequence q-axis current, respectively. and are the d-axis component and q-axis component of the stator side grid positive sequence voltage, respectively. and are the d-axis component and q-axis component of the stator positive sequence voltage, respectively, K p1 and K i1 are the proportional coefficient and integral coefficient of the stator reactive power controller, K p2 and K i2 are the proportional coefficient and integral coefficient of the stator q-axis voltage controller, respectively. and are the d-axis component and q-axis component of the negative sequence voltage reference value of the three-phase series converter on the stator side, T e2ωs is the electromagnetic torque twice the stator frequency fluctuation component, Q s2ωs K is the stator reactive power twice the stator frequency fluctuation component, p3 and K i3 are the proportional coefficient and integral coefficient of the electromagnetic torque twice stator frequency fluctuation component controller, K p4 and K i4 are the proportional coefficient and integral coefficient of the stator reactive power twice stator frequency fluctuation component controller, and are the d-axis component and q-axis component of the fifth harmonic voltage reference value of the three-phase series converter on the stator side, T e6ωs is the electromagnetic torque six times the stator frequency fluctuation component, Q s6ωs is the stator reactive power six times the stator frequency fluctuation component, K p5 and K i5 are the proportional coefficient and integral coefficient of the first electromagnetic torque six times stator frequency fluctuation component controller, K p6 and K i6 are the proportional coefficient and integral coefficient of the first stator reactive six times stator frequency fluctuation component controller, and are the d-axis component and q-axis component of the seventh harmonic voltage reference value of the three-phase converter in series on the stator side, K p7 and K i7 are the proportional coefficient and integral coefficient of the controller of the second electromagnetic torque six times the stator frequency fluctuation component, K p8 and K i8 They are respectively the proportional coefficient and integral coefficient of the second stator reactive power six times stator frequency fluctuation component controller.

[0047] Optionally, the second preset voltage control calculation formula is:

[0048]

[0049] in, and are the d-axis component and q-axis component of the positive sequence voltage reference value of the three-phase converter in series on the rotor side, and are the d-axis component and q-axis component of the rotor-side grid positive sequence voltage, respectively. and are the d-axis component and q-axis component of the rotor positive sequence voltage, respectively, K p9 and K i9 are the proportional coefficient and integral coefficient of the rotor d-axis voltage controller, K p10 and K i10 are the proportional coefficient and integral coefficient of the rotor q-axis voltage controller, respectively. and are the d-axis component and q-axis component of the negative sequence voltage reference value of the three-phase converter in series on the rotor side, T e2ωr is the electromagnetic torque twice the rotor frequency fluctuation component, Q s2ωr is the stator reactive power twice the rotor frequency fluctuation component, K p11 and K i11 are the proportional coefficient and integral coefficient of the electromagnetic torque double rotor frequency fluctuation component controller, K p12 and K i12 are the proportional coefficient and integral coefficient of the stator reactive power double rotor frequency fluctuation component controller, and are the d-axis component and q-axis component of the fifth harmonic voltage reference value of the three-phase converter in series on the rotor side, T e6ωr is the electromagnetic torque six times the rotor frequency fluctuation component, Q s6ωr is the stator reactive power six times the rotor frequency fluctuation component, K p13 and K i13 are the proportional coefficient and integral coefficient of the first electromagnetic torque six times rotor frequency fluctuation component controller, K p14 and K i14 are the proportional coefficient and integral coefficient of the first stator reactive six-times rotor frequency fluctuation component controller, and are the d-axis component and q-axis component of the seventh harmonic voltage reference value of the three-phase converter in series on the rotor side, K p15 and K i15 are the proportional coefficient and integral coefficient of the second electromagnetic torque six times rotor frequency fluctuation component controller, K p16 and K i16 They are respectively the proportional coefficient and integral coefficient of the second stator reactive six times rotor frequency fluctuation component controller.

[0050] Optionally, determining the stator side series three-phase converter voltage reference value in a two-phase stator stationary coordinate system according to the stator side series three-phase converter positive sequence voltage reference value DC component, the stator side series three-phase converter negative sequence voltage reference value DC component, the stator side series three-phase converter fifth harmonic voltage reference value DC component and the stator side series three-phase converter seventh harmonic voltage reference value DC component comprises:

[0051] Respectively perform two-phase rotation to two-phase stationary coordinate transformation on the positive-sequence voltage reference value DC component of the stator-side series three-phase converter, the negative-sequence voltage reference value DC component of the stator-side series three-phase converter, the fifth-order harmonic voltage reference value DC component of the stator-side series three-phase converter, and the seventh-order harmonic voltage reference value DC component of the stator-side series three-phase converter, to obtain the positive-sequence voltage reference value of the stator-side series three-phase converter, the negative-sequence voltage reference value of the stator-side series three-phase converter, the fifth-order harmonic voltage reference value of the stator-side series three-phase converter, and the seventh-order harmonic voltage reference value of the stator-side series three-phase converter in a two-phase stator stationary coordinate system;

[0052] The sum of the positive sequence voltage reference value of the stator side series three-phase converter, the negative sequence voltage reference value of the stator side series three-phase converter, the fifth harmonic voltage reference value of the stator side series three-phase converter and the seventh harmonic voltage reference value of the stator side series three-phase converter is used as the voltage reference value of the stator side series three-phase converter.

[0053] Optionally, determining the voltage reference value of the rotor-side series three-phase converter in a two-phase rotor rotating coordinate system according to a positive-sequence voltage reference value DC component of the rotor-side series three-phase converter, a negative-sequence voltage reference value DC component of the rotor-side series three-phase converter, a fifth harmonic voltage reference value DC component of the rotor-side series three-phase converter, and a seventh harmonic voltage reference value DC component of the rotor-side series three-phase converter includes:

[0054] Respectively perform two-phase rotation to two-phase stationary coordinate transformation on the positive-sequence voltage reference value DC component of the rotor-side series three-phase converter, the negative-sequence voltage reference value DC component of the rotor-side series three-phase converter, the fifth-order harmonic voltage reference value DC component of the rotor-side series three-phase converter, and the seventh-order harmonic voltage reference value DC component of the rotor-side series three-phase converter, to obtain the positive-sequence voltage reference value of the rotor-side series three-phase converter, the negative-sequence voltage reference value of the rotor-side series three-phase converter, the fifth-order harmonic voltage reference value of the rotor-side series three-phase converter, and the seventh-order harmonic voltage reference value of the rotor-side series three-phase converter in a two-phase rotor rotating coordinate system;

[0055] The sum of the positive sequence voltage reference value of the rotor side series three-phase converter, the negative sequence voltage reference value of the rotor side series three-phase converter, the fifth harmonic voltage reference value of the rotor side series three-phase converter and the seventh harmonic voltage reference value of the rotor side series three-phase converter is used as the voltage reference value of the rotor side series three-phase converter in the two-phase rotor rotating coordinate system.

[0056] In a second aspect, an embodiment of the present invention provides a variable frequency transformer torque and reactive power fluctuation suppression device, comprising:

[0057] The variable calculation device applied to the control system comprises:

[0058] A first acquisition module is used to acquire a stator side grid voltage, a stator voltage, a rotor side grid voltage, a rotor voltage, a stator current, a rotor current, a pole pair number and an excitation inductance;

[0059] a parameter determination module, for obtaining, based on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, a stator side grid phase angle, a rotor side grid phase angle, a stator side grid positive sequence voltage DC component, a stator positive sequence voltage DC component, a rotor side grid positive sequence voltage DC component, a rotor positive sequence voltage DC component, a stator positive sequence current DC component, a rotor positive sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power twice rotor frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component and a stator reactive power six times rotor frequency fluctuation component;

[0060] The control device applied to the stator-side series three-phase converter comprises:

[0061] A first parameter determination module is used to calculate the positive sequence voltage reference value DC component of the stator side series three-phase converter, the negative sequence voltage reference value DC component of the stator side series three-phase converter, the fifth harmonic voltage reference value DC component of the stator side series three-phase converter, and the seventh harmonic voltage reference value DC component of the stator side series three-phase converter based on the phase angle of the stator side power grid, the positive sequence voltage DC component of the stator side power grid, the stator positive sequence voltage DC component, the stator positive sequence current DC component, the electromagnetic torque twice the stator frequency fluctuation component, the electromagnetic torque six times the stator frequency fluctuation component, the stator reactive power twice the stator frequency fluctuation component, and the stator reactive power six times the stator frequency fluctuation component, in combination with a first preset voltage control calculation formula;

[0062] A first reference value determination module is used to determine the stator side series three-phase converter voltage reference value in a two-phase stator stationary coordinate system according to the stator side series three-phase converter positive sequence voltage reference value DC component, the stator side series three-phase converter negative sequence voltage reference value DC component, the stator side series three-phase converter fifth harmonic voltage reference value DC component and the stator side series three-phase converter seventh harmonic voltage reference value DC component;

[0063] A first control signal determination module is used to obtain a control signal of a stator-side series three-phase converter switch by performing space vector modulation on the stator-side series three-phase converter voltage reference value; the control signal of the stator-side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced stator-side grid voltage and harmonic distortion;

[0064] The control device applied to the rotor-side series three-phase converter comprises:

[0065] A second parameter determination module is used to calculate the positive sequence voltage reference value DC component of the rotor side series three-phase converter, the negative sequence voltage reference value DC component of the rotor side series three-phase converter, the fifth harmonic voltage reference value DC component of the rotor side series three-phase converter, and the seventh harmonic voltage reference value DC component of the rotor side series three-phase converter based on the rotor side grid phase angle, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the electromagnetic torque twice the rotor frequency fluctuation component, the electromagnetic torque six times the rotor frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, and the stator reactive power six times the rotor frequency fluctuation component, in combination with a second preset voltage control calculation formula;

[0066] A second reference value determination module is used to determine the rotor side series three-phase converter voltage reference value in a two-phase rotor rotating coordinate system according to the rotor side series three-phase converter positive sequence voltage reference value DC component, the rotor side series three-phase converter negative sequence voltage reference value DC component, the rotor side series three-phase converter fifth harmonic voltage reference value DC component and the rotor side series three-phase converter seventh harmonic voltage reference value DC component;

[0067] The second control signal determination module is used to obtain a control signal of the rotor side series three-phase converter switch by performing space vector modulation on the rotor side series three-phase converter voltage reference value; the control signal of the rotor side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced rotor side grid voltage and harmonic distortion.

[0068] A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program code, and the program code is used to execute the variable frequency transformer torque and reactive power fluctuation suppression method described in the first aspect.

[0069] It can be seen from the above technical solutions that the present invention has the following advantages:

[0070] The present invention discloses a method and device for suppressing torque and reactive power fluctuation of a variable frequency transformer. The control method is applied to a control system, a stator-side series three-phase converter and a rotor-side series three-phase converter; a variable calculation method applied to the control system comprises: obtaining a stator-side grid voltage, a stator voltage, a rotor-side grid voltage, a rotor voltage, a stator current, a rotor current, a pole pair number and an excitation inductance; based on the stator-side grid voltage, the stator voltage, the rotor-side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, obtaining a stator-side grid phase angle, a rotor-side grid phase angle, a stator-side grid positive sequence voltage DC component and an excitation inductance. The invention relates to a control method for a stator side series three-phase converter, comprising: determining a stator positive sequence voltage DC component, a rotor side grid positive sequence voltage DC component, a rotor positive sequence voltage DC component, a stator positive sequence current DC component, a rotor positive sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power twice rotor frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component, and a stator reactive power six times rotor frequency fluctuation component; and a control method for a stator side series three-phase converter, comprising: determining a stator positive sequence voltage DC component, a rotor side grid positive sequence voltage DC component, a stator positive sequence current DC component, a rotor positive sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component, and a stator reactive power six times rotor frequency fluctuation component based on the phase angle of the stator side grid, the stator side grid positive sequence voltage DC component, and the rotor positive sequence current DC component. The voltage DC component, the stator positive sequence voltage DC component, the stator positive sequence current DC component, the electromagnetic torque twice the stator frequency fluctuation component, the electromagnetic torque six times the stator frequency fluctuation component, the stator reactive power twice the stator frequency fluctuation component and the stator reactive power six times the stator frequency fluctuation component are combined with the first preset voltage control calculation formula to calculate the positive sequence voltage reference value DC component of the stator side series three-phase converter, the negative sequence voltage reference value DC component of the stator side series three-phase converter, the fifth harmonic voltage reference value DC component of the stator side series three-phase converter and the seventh harmonic voltage reference value DC component of the stator side series three-phase converter; according to the positive sequence of the stator side series three-phase converter The voltage reference value DC component, the negative sequence voltage reference value DC component of the stator side series three-phase converter, the fifth harmonic voltage reference value DC component of the stator side series three-phase converter and the seventh harmonic voltage reference value DC component of the stator side series three-phase converter are used to determine the stator side series three-phase converter voltage reference value in a two-phase stator stationary coordinate system; by performing space vector modulation on the stator side series three-phase converter voltage reference value, a control signal of the stator side series three-phase converter switch is obtained; the control signal of the stator side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced stator side grid voltage and harmonic distortion;The control method applied to the rotor-side series three-phase converter includes: based on the rotor-side grid phase angle, the rotor-side grid positive-sequence voltage DC component, the rotor positive-sequence voltage DC component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times rotor frequency fluctuation component, the stator reactive power twice rotor frequency fluctuation component and the stator reactive power six times rotor frequency fluctuation component, in combination with a second preset voltage control calculation formula, calculating the rotor-side series three-phase converter positive-sequence voltage reference DC component, the rotor-side series three-phase converter negative-sequence voltage reference DC component, the rotor-side series three-phase converter fifth harmonic voltage reference DC component and the rotor-side series three-phase converter seventh harmonic voltage reference DC component; According to the DC component of the positive sequence voltage reference value of the rotor side series three-phase converter, the DC component of the negative sequence voltage reference value of the rotor side series three-phase converter, the DC component of the fifth harmonic voltage reference value of the rotor side series three-phase converter and the DC component of the seventh harmonic voltage reference value of the rotor side series three-phase converter, the voltage reference value of the rotor side series three-phase converter in the two-phase rotor rotating coordinate system is determined; by performing space vector modulation on the voltage reference value of the rotor side series three-phase converter, a control signal of the rotor side series three-phase converter switch is obtained; the control signal of the rotor side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced voltage and harmonic distortion of the rotor side grid. ;

[0071] Compared with the prior art, the present invention maintains the DC bus voltage stability through a parallel three-phase converter, and solves the problem of unbalanced grid voltage and harmonic distortion on both sides through two series three-phase converters, which can completely suppress the torque and reactive power fluctuations of the variable frequency transformer caused by the negative sequence component and harmonic component in the unbalanced and harmonically distorted grid voltage. At the same time, since the second-order filter used is greatly reduced, it is beneficial to improve the response speed and stability of the control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0073] Figure 1 A flow chart of the steps of a variable calculation method applied to the control system in a variable frequency transformer torque and reactive power fluctuation suppression method of the present invention;

[0074] Figure 2A flow chart of the steps of a control method applied to the stator-side series three-phase converter in a variable frequency transformer torque and reactive power fluctuation suppression method of the present invention;

[0075] Figure 3 A flow chart of the steps of a control method applied to the rotor-side series three-phase converter in a variable frequency transformer torque and reactive power fluctuation suppression method of the present invention;

[0076] Figure 4 A variable frequency transformer fault ride-through circuit is an example of the present invention;

[0077] Figure 5 A flow chart of a control system variable calculation method according to an example of the present invention;

[0078] Figure 6 It is a flow chart of a control method applied to a stator-side series three-phase converter according to an example of the present invention;

[0079] Figure 7 It is a flow chart of a control method applied to a rotor-side series three-phase converter as an example of the present invention;

[0080] Figure 8 The present invention is a structural block diagram of an embodiment of a variable frequency transformer torque and reactive power fluctuation suppression device of the present invention. DETAILED DESCRIPTION

[0081] The embodiment of the present invention provides a method and device for suppressing torque and reactive power fluctuations of a variable frequency transformer, which is used to maintain the stability of the DC bus voltage through a parallel three-phase converter, and solve the problems of unbalanced grid voltage and harmonic distortion on both sides through two series three-phase converters, thereby completely suppressing the torque and reactive power fluctuations of the variable frequency transformer caused by the negative sequence components and harmonic components in the unbalanced and harmonically distorted grid voltage.

[0082] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0083] There are two main methods for dealing with the fault ride-through problem of variable frequency transformers: one existing method is to use a parallel three-phase converter and a series three-phase converter on the stator side, so as to maintain the DC bus voltage stability through the parallel three-phase converter, and to achieve independent control of reactive power through the series three-phase converter, and to maintain the symmetry and sinusoidality of the stator current. However, this method only involves how to solve the problem of unbalanced grid voltage and harmonic distortion on both sides of the variable frequency transformer by controlling a series three-phase converter, but cannot completely suppress the fluctuation of torque and reactive power of the variable frequency transformer.

[0084] Another existing method is to use a series three-phase converter on the stator side and the rotor side respectively, so that the series three-phase converter on the stator side can maintain the DC bus voltage constant, independently control the reactive power, and suppress the stator negative sequence voltage and harmonic voltage, while the series three-phase converter on the rotor side can suppress the rotor negative sequence voltage and harmonic voltage. However, this method only involves how to solve the voltage imbalance and harmonic problems of the two sides of the power grid at the same time by controlling two series three-phase converters. Due to the limited number of degrees of freedom, it is impossible to completely suppress the torque and reactive power fluctuations of the variable frequency transformer.

[0085] In order to solve the problems existing in the two existing variable frequency transformer torque and reactive power fluctuation suppression methods, an embodiment of the present invention provides a variable frequency transformer torque and reactive power fluctuation suppression method, which is applied to both the stator side series three-phase converter and the rotor side series three-phase converter;

[0086] See also Figure 1 , Figure 1 The present invention is a flow chart of the steps of a variable calculation method applied to the control system in a variable frequency transformer torque and reactive power fluctuation suppression method, the steps comprising:

[0087] S11, obtaining the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current, the rotor current, the number of pole pairs and the excitation inductance;

[0088] S12, based on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, obtain the stator side grid phase angle, the rotor side grid phase angle, the stator side grid positive sequence voltage DC component, the stator positive sequence voltage DC component, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the stator positive sequence current DC component, the rotor positive sequence current DC component, the electromagnetic torque twice the stator frequency fluctuation component, the electromagnetic torque twice the rotor frequency fluctuation component, the electromagnetic torque six times the stator frequency fluctuation component, the electromagnetic torque six times the rotor frequency fluctuation component, the stator reactive power twice the stator frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, the stator reactive power six times the stator frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component;

[0089] Specifically include:

[0090] The stator side grid voltage and the rotor side grid voltage are processed respectively by a digital phase-locked loop to obtain the stator side grid phase angle and the rotor side grid phase angle;

[0091] Based on the stator-side grid phase angle and the rotor-side grid phase angle, coordinate transformation is performed on the stator-side grid voltage, the stator voltage, the rotor-side grid voltage, the rotor voltage, the stator current, and the rotor current to obtain the stator-side grid positive-sequence voltage DC component, the stator positive-sequence voltage DC component, the rotor-side grid positive-sequence voltage DC component, the rotor positive-sequence voltage DC component, the stator positive-sequence current DC component, and the rotor positive-sequence current DC component;

[0092] Based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance, the electromagnetic torque twice stator frequency fluctuation component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times stator frequency fluctuation component and the electromagnetic torque six times rotor frequency fluctuation component are obtained;

[0093] Based on the stator positive-sequence voltage DC component and the stator positive-sequence current DC component, the stator reactive power twice the stator frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, the stator reactive power six times the stator frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component are obtained.

[0094] In an optional embodiment, based on the stator side grid phase angle and the rotor side grid phase angle, coordinate transformation is performed on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current, and the rotor current to obtain the stator side grid positive sequence voltage DC component, the stator positive sequence voltage DC component, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the stator positive sequence current DC component, and the rotor positive sequence current DC component, including:

[0095] Based on the phase angle of the stator-side power grid, the stator voltage and the stator current are transformed from three-phase static to two-phase rotating coordinates to obtain the stator-side power grid positive-sequence voltage DC component, the stator positive-sequence voltage DC component and the stator positive-sequence current DC component;

[0096] Based on the rotor-side grid phase angle, the rotor-side grid voltage, the rotor voltage and the rotor current are transformed from three-phase static to two-phase rotating coordinates to obtain the rotor-side grid positive-sequence voltage DC component, the rotor positive-sequence voltage DC component and the rotor positive-sequence current DC component.

[0097] In an optional embodiment, based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance, the electromagnetic torque twice stator frequency fluctuation component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times stator frequency fluctuation component and the electromagnetic torque six times rotor frequency fluctuation component are obtained, including:

[0098] The electromagnetic torque is calculated based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance in combination with the electromagnetic torque calculation formula; the electromagnetic torque calculation formula is specifically:

[0099]

[0100] Among them, T e is the electromagnetic torque, p n is the pole pair number, L m is the magnetizing inductance, and are the d-axis component and q-axis component of the stator positive sequence current respectively, and They are the d-axis component and q-axis component of the rotor positive sequence current respectively;

[0101] Based on the electromagnetic torque, a double stator frequency fluctuation component of the electromagnetic torque is obtained by passing it through a bandpass filter of a first preset center frequency;

[0102] Based on the electromagnetic torque, a double rotor frequency fluctuation component of the electromagnetic torque is obtained through a bandpass filter of a second preset center frequency;

[0103] Based on the electromagnetic torque, a six-fold stator frequency fluctuation component of the electromagnetic torque is obtained by passing it through a bandpass filter of a third preset center frequency;

[0104] Based on the electromagnetic torque, a six-fold rotor frequency fluctuation component of the electromagnetic torque is obtained through a bandpass filter with a fourth preset center frequency.

[0105] In an optional embodiment, based on the stator positive sequence voltage DC component and the stator positive sequence current DC component, the stator reactive power twice the stator frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, the stator reactive power six times the stator frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component are obtained, including:

[0106] Based on the stator positive sequence voltage DC component and the stator positive sequence current DC component, combined with the reactive power calculation formula, the stator reactive power is calculated; the reactive power calculation formula is specifically:

[0107]

[0108] Among them, Q s is the stator reactive power, and are the d-axis component and q-axis component of the stator positive sequence voltage respectively;

[0109] Based on the stator reactive power, a stator reactive power fluctuation component of twice the stator frequency is obtained by passing the stator reactive power through a bandpass filter of the first preset center frequency;

[0110] Based on the stator reactive power, a twice rotor frequency fluctuation component of the stator reactive power is obtained through a bandpass filter of the second preset center frequency;

[0111] Based on the stator reactive power, a six-fold stator frequency fluctuation component of the stator reactive power is obtained through a bandpass filter of the third preset center frequency;

[0112] Based on the stator reactive power, the stator reactive power six times rotor frequency fluctuation component is obtained through the bandpass filter of the fourth preset center frequency.

[0113] See also Figure 2 , Figure 2 The present invention is a flow chart of the steps of a control method applied to the stator-side series three-phase converter in a variable frequency transformer torque and reactive power fluctuation suppression method of the present invention, the steps comprising:

[0114] S21, based on the phase angle of the stator side power grid, the stator side power grid positive sequence voltage DC component, the stator positive sequence voltage DC component, the stator positive sequence current DC component, the electromagnetic torque twice the stator frequency fluctuation component, the electromagnetic torque six times the stator frequency fluctuation component, the stator reactive power twice the stator frequency fluctuation component and the stator reactive power six times the stator frequency fluctuation component, in combination with a first preset voltage control calculation formula, calculate the stator side series three-phase converter positive sequence voltage reference value DC component, the stator side series three-phase converter negative sequence voltage reference value DC component, the stator side series three-phase converter fifth harmonic voltage reference value DC component and the stator side series three-phase converter seventh harmonic voltage reference value DC component;

[0115] The first preset voltage control calculation formula is:

[0116]

[0117] Where s is the Laplace operator, and are the d-axis component and q-axis component of the positive sequence voltage reference value of the three-phase converter in series on the stator side, and are the reference value and actual value of the stator positive sequence q-axis current, respectively. and are the d-axis component and q-axis component of the stator side grid positive sequence voltage, respectively. and are the d-axis component and q-axis component of the stator positive sequence voltage, respectively, K p1 and K i1 are the proportional coefficient and integral coefficient of the stator reactive power controller, K p2 and K i2 are the proportional coefficient and integral coefficient of the stator q-axis voltage controller, respectively. and are the d-axis component and q-axis component of the negative sequence voltage reference value of the three-phase series converter on the stator side, T e2ωs is the electromagnetic torque twice the stator frequency fluctuation component, Q s2ωs K is the stator reactive power twice the stator frequency fluctuation component, p3 and K i3 are the proportional coefficient and integral coefficient of the electromagnetic torque twice stator frequency fluctuation component controller, K p4 and K i4 are the proportional coefficient and integral coefficient of the stator reactive power twice stator frequency fluctuation component controller, and are the d-axis component and q-axis component of the fifth harmonic voltage reference value of the three-phase series converter on the stator side, T e6ωs is the electromagnetic torque six times the stator frequency fluctuation component, Q s6ωsis the stator reactive power six times the stator frequency fluctuation component, K p5 and K i5 are the proportional coefficient and integral coefficient of the first electromagnetic torque six times stator frequency fluctuation component controller, K p6 and K i6 are the proportional coefficient and integral coefficient of the first stator reactive six times stator frequency fluctuation component controller, and are the d-axis component and q-axis component of the seventh harmonic voltage reference value of the three-phase converter in series on the stator side, K p7 and K i7 are the proportional coefficient and integral coefficient of the controller of the second electromagnetic torque six times the stator frequency fluctuation component, K p8 and K i8 They are respectively the proportional coefficient and integral coefficient of the second stator reactive power six times stator frequency fluctuation component controller.

[0118] S22, determining a voltage reference value of the stator side series three-phase converter in a two-phase stator stationary coordinate system according to a DC component of a positive-sequence voltage reference value of the stator side series three-phase converter, a DC component of a negative-sequence voltage reference value of the stator side series three-phase converter, a DC component of a fifth harmonic voltage reference value of the stator side series three-phase converter, and a DC component of a seventh harmonic voltage reference value of the stator side series three-phase converter;

[0119] Specifically include:

[0120] Respectively perform two-phase rotation to two-phase stationary coordinate transformation on the positive-sequence voltage reference value DC component of the stator-side series three-phase converter, the negative-sequence voltage reference value DC component of the stator-side series three-phase converter, the fifth-order harmonic voltage reference value DC component of the stator-side series three-phase converter, and the seventh-order harmonic voltage reference value DC component of the stator-side series three-phase converter, to obtain the positive-sequence voltage reference value of the stator-side series three-phase converter, the negative-sequence voltage reference value of the stator-side series three-phase converter, the fifth-order harmonic voltage reference value of the stator-side series three-phase converter, and the seventh-order harmonic voltage reference value of the stator-side series three-phase converter in a two-phase stator stationary coordinate system;

[0121] The sum of the positive sequence voltage reference value of the stator side series three-phase converter, the negative sequence voltage reference value of the stator side series three-phase converter, the fifth harmonic voltage reference value of the stator side series three-phase converter and the seventh harmonic voltage reference value of the stator side series three-phase converter is used as the voltage reference value of the stator side series three-phase converter.

[0122] S23, by performing space vector modulation on the voltage reference value of the stator side series three-phase converter, a control signal of the stator side series three-phase converter switch is obtained; the control signal of the stator side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced stator side grid voltage and harmonic distortion.

[0123] See also Figure 3 , Figure 3 The present invention is a flow chart of the steps of a control method for a variable frequency transformer torque and reactive power fluctuation suppression method applied to the rotor side series three-phase converter, the steps comprising:

[0124] S31, based on the rotor side grid phase angle, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times rotor frequency fluctuation component, the stator reactive power twice rotor frequency fluctuation component and the stator reactive power six times rotor frequency fluctuation component, in combination with a second preset voltage control calculation formula, calculate the rotor side series three-phase converter positive sequence voltage reference value DC component, the rotor side series three-phase converter negative sequence voltage reference value DC component, the rotor side series three-phase converter fifth harmonic voltage reference value DC component and the rotor side series three-phase converter seventh harmonic voltage reference value DC component;

[0125] The second preset voltage control calculation formula is:

[0126]

[0127] in, and are the d-axis component and q-axis component of the positive sequence voltage reference value of the three-phase converter in series on the rotor side, and are the d-axis component and q-axis component of the rotor-side grid positive sequence voltage, respectively. and are the d-axis component and q-axis component of the rotor positive sequence voltage, respectively, K p9 and K i9 are the proportional coefficient and integral coefficient of the rotor d-axis voltage controller, K p10 and K i10 are the proportional coefficient and integral coefficient of the rotor q-axis voltage controller, respectively. and are the d-axis component and q-axis component of the negative sequence voltage reference value of the three-phase converter in series on the rotor side, T e2ωr is the electromagnetic torque twice the rotor frequency fluctuation component, Q s2ωr is the stator reactive power twice the rotor frequency fluctuation component, K p11 and K i11are the proportional coefficient and integral coefficient of the electromagnetic torque double rotor frequency fluctuation component controller, K p12 and K i12 are the proportional coefficient and integral coefficient of the stator reactive power double rotor frequency fluctuation component controller, and are the d-axis component and q-axis component of the fifth harmonic voltage reference value of the three-phase converter in series on the rotor side, T e6ωr is the electromagnetic torque six times the rotor frequency fluctuation component, Q s6ωr is the stator reactive power six times the rotor frequency fluctuation component, K p13 and K i13 are the proportional coefficient and integral coefficient of the first electromagnetic torque six times rotor frequency fluctuation component controller, K p14 and K i14 are the proportional coefficient and integral coefficient of the first stator reactive six-times rotor frequency fluctuation component controller, and are the d-axis component and q-axis component of the seventh harmonic voltage reference value of the three-phase converter in series on the rotor side, K p15 and K i15 are the proportional coefficient and integral coefficient of the second electromagnetic torque six times rotor frequency fluctuation component controller, K p16 and K i16 They are respectively the proportional coefficient and integral coefficient of the second stator reactive six times rotor frequency fluctuation component controller.

[0128] S32, determining a voltage reference value of the rotor side series three-phase converter in a two-phase rotor rotating coordinate system according to a DC component of a positive sequence voltage reference value of the rotor side series three-phase converter, a DC component of a negative sequence voltage reference value of the rotor side series three-phase converter, a DC component of a fifth harmonic voltage reference value of the rotor side series three-phase converter, and a DC component of a seventh harmonic voltage reference value of the rotor side series three-phase converter;

[0129] Specifically include:

[0130] Respectively perform two-phase rotation to two-phase stationary coordinate transformation on the positive-sequence voltage reference value DC component of the rotor-side series three-phase converter, the negative-sequence voltage reference value DC component of the rotor-side series three-phase converter, the fifth-order harmonic voltage reference value DC component of the rotor-side series three-phase converter, and the seventh-order harmonic voltage reference value DC component of the rotor-side series three-phase converter, to obtain the positive-sequence voltage reference value of the rotor-side series three-phase converter, the negative-sequence voltage reference value of the rotor-side series three-phase converter, the fifth-order harmonic voltage reference value of the rotor-side series three-phase converter, and the seventh-order harmonic voltage reference value of the rotor-side series three-phase converter in a two-phase rotor rotating coordinate system;

[0131] The sum of the positive sequence voltage reference value of the rotor side series three-phase converter, the negative sequence voltage reference value of the rotor side series three-phase converter, the fifth harmonic voltage reference value of the rotor side series three-phase converter and the seventh harmonic voltage reference value of the rotor side series three-phase converter is used as the voltage reference value of the rotor side series three-phase converter in the two-phase rotor rotating coordinate system.

[0132] S33, obtaining a control signal of a rotor-side series three-phase converter switch by performing space vector modulation on the rotor-side series three-phase converter voltage reference value; the control signal of the rotor-side series three-phase converter switch is used to suppress fluctuations of electromagnetic torque and stator reactive power of the variable frequency transformer caused by unbalanced rotor-side grid voltage and harmonic distortion;

[0133] A method for suppressing torque and reactive power fluctuations of a variable frequency transformer disclosed in an embodiment of the present invention is applied to a control system, a stator-side series three-phase converter and a rotor-side series three-phase converter; a variable calculation method applied to the control system comprises: obtaining a stator-side grid voltage, a stator voltage, a rotor-side grid voltage, a rotor voltage, a stator current, a rotor current, a pole pair number and an excitation inductance; based on the stator-side grid voltage, the stator voltage, the rotor-side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, obtaining a stator-side grid phase angle, a rotor-side grid phase angle, a stator-side grid positive sequence voltage DC component and a rotor-side grid positive sequence voltage DC component. , stator positive sequence voltage DC component, rotor side grid positive sequence voltage DC component, rotor positive sequence voltage DC component, stator positive sequence current DC component, rotor positive sequence current DC component, electromagnetic torque twice stator frequency fluctuation component, electromagnetic torque twice rotor frequency fluctuation component, electromagnetic torque six times stator frequency fluctuation component, electromagnetic torque six times rotor frequency fluctuation component, stator reactive power twice stator frequency fluctuation component, stator reactive power twice rotor frequency fluctuation component, stator reactive power six times stator frequency fluctuation component and stator reactive power six times rotor frequency fluctuation component; the control method applied to the stator side series three-phase converter, comprising: based on the phase angle of the stator side grid, the stator side grid positive sequence voltage The DC component, the stator positive sequence voltage DC component, the stator positive sequence current DC component, the electromagnetic torque twice stator frequency fluctuation component, the electromagnetic torque six times stator frequency fluctuation component, the stator reactive power twice stator frequency fluctuation component and the stator reactive power six times stator frequency fluctuation component are combined with the first preset voltage control calculation formula to calculate the positive sequence voltage reference value DC component of the stator side series three-phase converter, the negative sequence voltage reference value DC component of the stator side series three-phase converter, the fifth harmonic voltage reference value DC component of the stator side series three-phase converter and the seventh harmonic voltage reference value DC component of the stator side series three-phase converter; according to the positive sequence of the stator side series three-phase converter The voltage reference value DC component, the negative sequence voltage reference value DC component of the stator side series three-phase converter, the fifth harmonic voltage reference value DC component of the stator side series three-phase converter and the seventh harmonic voltage reference value DC component of the stator side series three-phase converter are used to determine the stator side series three-phase converter voltage reference value in a two-phase stator stationary coordinate system; by performing space vector modulation on the stator side series three-phase converter voltage reference value, a control signal of the stator side series three-phase converter switch is obtained; the control signal of the stator side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced stator side grid voltage and harmonic distortion;The control method applied to the rotor-side series three-phase converter includes: based on the rotor-side grid phase angle, the rotor-side grid positive-sequence voltage DC component, the rotor positive-sequence voltage DC component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times rotor frequency fluctuation component, the stator reactive power twice rotor frequency fluctuation component and the stator reactive power six times rotor frequency fluctuation component, in combination with a second preset voltage control calculation formula, calculating the rotor-side series three-phase converter positive-sequence voltage reference DC component, the rotor-side series three-phase converter negative-sequence voltage reference DC component, the rotor-side series three-phase converter fifth harmonic voltage reference DC component and the rotor-side series three-phase converter seventh harmonic voltage reference DC component; According to the DC component of the positive sequence voltage reference value of the rotor side series three-phase converter, the DC component of the negative sequence voltage reference value of the rotor side series three-phase converter, the DC component of the fifth harmonic voltage reference value of the rotor side series three-phase converter and the DC component of the seventh harmonic voltage reference value of the rotor side series three-phase converter, the voltage reference value of the rotor side series three-phase converter in the two-phase rotor rotating coordinate system is determined; by performing space vector modulation on the voltage reference value of the rotor side series three-phase converter, a control signal of the rotor side series three-phase converter switch is obtained; the control signal of the rotor side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced voltage and harmonic distortion of the rotor side grid. ;

[0134] Compared with the prior art, the present invention maintains the DC bus voltage stability through a parallel three-phase converter, and solves the problem of unbalanced grid voltage and harmonic distortion on both sides through two series three-phase converters, which can completely suppress the torque and reactive power fluctuations of the variable frequency transformer caused by the negative sequence component and harmonic component in the unbalanced and harmonically distorted grid voltage. At the same time, since the second-order filter used is greatly reduced, it is beneficial to improve the response speed and stability of the control system.

[0135] To facilitate those skilled in the art to understand the technical solution of the present invention, the data flow of a method for suppressing torque and reactive power fluctuations of a variable frequency transformer of the present invention is illustrated below.

[0136] It should be noted that the three examples mentioned in the examples of the present invention are all applied to Figure 4 A variable frequency transformer fault ride-through circuit is shown in FIG. Figure 4 , where 1 is the stator side power grid, 2 is the stator side series three-phase transformer, 3 is the variable frequency transformer, 31 is the doubly fed machine, 32 is the DC machine, 4 is the rotor side series three-phase transformer, 5 is the rotor side power grid, 6 is the rotor side series three-phase transformer, 7 is the H-bridge converter, 8 is the stator side series three-phase transformer, 9 is the filter inductor, 10 is the parallel three-phase converter, 11 is the DC capacitor, and 12 is the control circuit.

[0137] For example 1, see Figure 5 , Figure 5 The flow chart of the control system variable calculation method according to the present invention is as follows: First, the stator side grid voltage u is collected by using a voltage sensor. sgabc , stator voltage u sabc , rotor side grid voltage u rgabc and rotor voltage u rabc , using the current sensor to collect the stator current i sabc and rotor current i rabc Then the stator side grid voltage u is respectively sgabc and rotor side grid voltage u rgabc Processing, get the stator side grid phase angle θ sg and rotor side grid phase θ rg Then, the phase angle θ of the stator side grid is sg The stator side grid voltage u sgabc , stator voltage u sabc and the stator current i sabc Perform coordinate transformation from three-phase static to two-phase rotating to obtain the d-axis component of the stator side grid positive sequence voltage and the q-axis component The d-axis component of the stator positive sequence voltage and the q-axis component The d-axis component of the stator positive sequence current and the q-axis component And through the rotor side grid phase θ rg The rotor side grid voltage u rgabc , rotor voltage u rabc and rotor current i rabc Perform coordinate transformation from three-phase static to two-phase rotating to obtain the d-axis component of the rotor side grid positive sequence voltage and the q-axis component The d-axis component of the rotor positive sequence voltage and the q-axis component The d-axis component of the rotor positive sequence current and the q-axis component Finally, according to the d-axis component of the stator positive sequence current and the q-axis component The d-axis component of the rotor positive sequence current and the q-axis component Pole pair number p n and the magnetizing inductance L m Calculate the electromagnetic torque and get the electromagnetic torque T e And the corresponding electromagnetic torque twice the stator frequency fluctuation component T e2ωs , electromagnetic torque twice rotor frequency fluctuation component Te2ωr , electromagnetic torque six times stator frequency fluctuation component T e6ωs and electromagnetic torque six times rotor frequency fluctuation component T e6ωr ; and the d-axis component of the stator positive sequence voltage and the q-axis component The d-axis component of the stator positive sequence current and the q-axis component Calculate the stator reactive power and obtain the stator reactive power Q s and its corresponding stator reactive power twice the stator frequency fluctuation component Q s2ωs , stator reactive power twice the rotor frequency fluctuation component Q s2ωr , stator reactive power six times stator frequency fluctuation component Q s6ωs and the stator reactive power six times the rotor frequency fluctuation component Q s6ωr .

[0138] For example 2, see Figure 6 , Figure 6 The flowchart of the control method of the present invention applied to the stator side series three-phase converter is as follows: first, according to the d-axis component of the stator side grid positive sequence voltage The q-axis component of the positive sequence voltage of the stator side grid The d-axis component of the stator positive sequence voltage The q-axis component of the stator positive sequence voltage The q-axis component of the stator positive sequence current Reference value of stator positive sequence q-axis current The d-axis component of the positive sequence voltage reference value of the three-phase converter in series on the stator side is calculated and the q-axis component According to the electromagnetic torque twice the stator frequency fluctuation component T e2ωs , stator reactive power twice stator frequency fluctuation component Q s2ωs , calculate the d-axis component of the negative sequence voltage reference value of the stator side series three-phase converter and the q-axis component According to the electromagnetic torque six times stator frequency fluctuation component T e6ωs , stator reactive power six times stator frequency fluctuation component Q s6ωs , calculate the d-axis component of the fifth harmonic voltage reference value of the stator-side series three-phase converter and the q-axis component And the d-axis component of the seventh harmonic voltage reference value of the stator-side series three-phase converter and the q-axis component Then, according to the d-axis component of the positive sequence voltage reference value of the stator-side series three-phase converter and the q-axis component The d-axis component of the negative sequence voltage reference value of the three-phase converter in series on the stator side and the q-axis component D-axis component of the fifth harmonic voltage reference value of the stator-side series three-phase converter and the q-axis component And the d-axis component of the seventh harmonic voltage reference value of the stator-side series three-phase converter and the q-axis component Determine the voltage reference value of the stator-side series three-phase converter in the two-phase stator stationary coordinate system Finally, the stator side series three-phase converter voltage reference value After space vector modulation (SVPWM), control signals S1, S2, and S3 of the three-phase converter switches in series on the stator side are obtained. Thus, through the control signals, the fluctuation of the torque and power of the variable frequency transformer caused by the unbalanced voltage and harmonic distortion of the stator side grid is suppressed.

[0139] For example three, see Figure 7 , Figure 7 The flowchart of the control method of the present invention applied to the rotor side series three-phase converter is shown as follows: first, according to the d-axis component of the rotor side grid positive sequence voltage The q-axis component of the positive sequence voltage of the rotor side grid The d-axis component of the rotor positive sequence voltage The q-axis component of the rotor positive sequence voltage The d-axis component of the positive sequence voltage reference value of the three-phase converter in series on the rotor side is calculated and the q-axis component According to the electromagnetic torque double rotor frequency fluctuation component Stator reactive power six times stator frequency fluctuation component The d-axis component of the negative sequence voltage reference value of the three-phase converter in series on the rotor side is calculated and the q-axis component According to the six times rotor frequency fluctuation component of electromagnetic torque Stator reactive power six times stator frequency fluctuation component The d-axis component of the fifth harmonic voltage reference value of the three-phase converter in series on the rotor side is calculated and the q-axis component And the d-axis component of the seventh harmonic voltage reference value of the rotor-side series three-phase converter and the q-axis component Then, according to the d-axis component of the positive sequence voltage reference value of the three-phase converter in series on the rotor side and the q-axis component The d-axis component of the negative sequence voltage reference value of the three-phase converter in series connection on the rotor side and the q-axis component D-axis component of the fifth harmonic voltage reference value of the three-phase converter in series connection on the rotor side and the q-axis component And the d-axis component of the seventh harmonic voltage reference value of the rotor-side series three-phase converter and the q-axis component Determine the voltage reference value of the three-phase converter in series on the rotor side in the two-phase rotor rotating coordinate system Finally, the rotor side is connected in series with the three-phase converter voltage reference value After space vector modulation (SVPWM), control signals S4, S5, and S6 of the three-phase converter switches in series on the rotor side are obtained, so that the fluctuation of the torque and power of the variable frequency transformer caused by the harmonic distortion of the rotor side grid voltage can be suppressed through the control signals.

[0140] See also Figure 8 , shows a structural block diagram of an embodiment of a variable frequency transformer torque and reactive power fluctuation suppression device of the present invention, the device comprising:

[0141] The variable calculation device applied to the control system comprises:

[0142] The first acquisition module 201 is used to acquire the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current, the rotor current, the number of pole pairs and the excitation inductance;

[0143] The parameter determination module 202 is used to obtain the stator side grid phase angle, the rotor side grid phase angle, the stator side grid positive sequence voltage DC component, the stator positive sequence voltage DC component, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the stator positive sequence current DC component, the rotor positive sequence current DC component, the electromagnetic torque twice the stator frequency fluctuation component, the electromagnetic torque twice the rotor frequency fluctuation component, the electromagnetic torque six times the stator frequency fluctuation component, the electromagnetic torque six times the rotor frequency fluctuation component, the stator reactive power twice the stator frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, the stator reactive power six times the stator frequency fluctuation component, and the stator reactive power six times the rotor frequency fluctuation component based on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance;

[0144] The control device applied to the stator-side series three-phase converter comprises:

[0145] The first parameter determination module 301 is used to calculate the positive sequence voltage reference value DC component of the stator side series three-phase converter, the negative sequence voltage reference value DC component of the stator side series three-phase converter, the fifth harmonic voltage reference value DC component of the stator side series three-phase converter, and the seventh harmonic voltage reference value DC component of the stator side series three-phase converter based on the phase angle of the stator side power grid, the positive sequence voltage DC component of the stator side power grid, the stator positive sequence voltage DC component, the stator positive sequence current DC component, the electromagnetic torque twice the stator frequency fluctuation component, the electromagnetic torque six times the stator frequency fluctuation component, the stator reactive power twice the stator frequency fluctuation component, and the stator reactive power six times the stator frequency fluctuation component, in combination with a first preset voltage control calculation formula;

[0146] The first reference value determination module 302 is used to determine the voltage reference value of the stator side series three-phase converter in a two-phase stator stationary coordinate system according to the DC component of the positive sequence voltage reference value of the stator side series three-phase converter, the DC component of the negative sequence voltage reference value of the stator side series three-phase converter, the DC component of the fifth harmonic voltage reference value of the stator side series three-phase converter, and the DC component of the seventh harmonic voltage reference value of the stator side series three-phase converter;

[0147] The first control signal determination module 303 is used to obtain a control signal of a stator-side series three-phase converter switch by performing space vector modulation on the stator-side series three-phase converter voltage reference value; the control signal of the stator-side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced stator-side grid voltage and harmonic distortion;

[0148] The control device applied to the rotor-side series three-phase converter comprises:

[0149] The second parameter determination module 401 is used to calculate the positive sequence voltage reference value DC component of the rotor side series three-phase converter, the negative sequence voltage reference value DC component of the rotor side series three-phase converter, the fifth harmonic voltage reference value DC component of the rotor side series three-phase converter, and the seventh harmonic voltage reference value DC component of the rotor side series three-phase converter based on the rotor side grid phase angle, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times rotor frequency fluctuation component, the stator reactive power twice rotor frequency fluctuation component, and the stator reactive power six times rotor frequency fluctuation component, in combination with a second preset voltage control calculation formula;

[0150] The second reference value determination module 402 is used to determine the rotor side series three-phase converter voltage reference value in the two-phase rotor rotating coordinate system according to the rotor side series three-phase converter positive sequence voltage reference value DC component, the rotor side series three-phase converter negative sequence voltage reference value DC component, the rotor side series three-phase converter fifth harmonic voltage reference value DC component and the rotor side series three-phase converter seventh harmonic voltage reference value DC component;

[0151] The second control signal determination module 403 is used to obtain a control signal of the rotor side series three-phase converter switch by performing space vector modulation on the rotor side series three-phase converter voltage reference value; the control signal of the rotor side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced rotor side grid voltage and harmonic distortion.

[0152] In an optional embodiment, the parameter determination module 202 includes:

[0153] A phase angle determination submodule, used for processing the stator side grid voltage and the rotor side grid voltage respectively through a digital phase-locked loop to obtain the stator side grid phase angle and the rotor side grid phase angle;

[0154] The DC component determination submodule is used to perform coordinate transformation on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current and the rotor current based on the stator side grid phase angle and the rotor side grid phase angle, respectively, to obtain the stator side grid positive sequence voltage DC component, the stator positive sequence voltage DC component, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the stator positive sequence current DC component and the rotor positive sequence current DC component.

[0155] In an optional embodiment, the parameter determination module 202 further includes:

[0156] A first fluctuation component determination submodule is used to obtain the electromagnetic torque twice stator frequency fluctuation component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times stator frequency fluctuation component and the electromagnetic torque six times rotor frequency fluctuation component based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance;

[0157] The second fluctuation component determination submodule is used to obtain the stator reactive power twice the stator frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, the stator reactive power six times the stator frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component based on the stator positive-sequence voltage DC component and the stator positive-sequence current DC component.

[0158] In an optional embodiment, the DC component determination submodule includes:

[0159] A first DC component determination unit is used to perform a three-phase stationary to two-phase rotating coordinate transformation on the stator side grid voltage, the stator voltage and the stator current based on the stator side grid phase angle to obtain the stator side grid positive sequence voltage DC component, the stator positive sequence voltage DC component and the stator positive sequence current DC component;

[0160] The second DC component determination unit is used to perform a three-phase stationary to two-phase rotating coordinate transformation on the rotor side grid voltage, the rotor voltage and the rotor current based on the rotor side grid phase angle to obtain the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component and the rotor positive sequence current DC component.

[0161] In an optional embodiment, the first fluctuation component determination submodule includes:

[0162] An electromagnetic torque determination unit, configured to calculate the electromagnetic torque based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance in combination with an electromagnetic torque calculation formula;

[0163] A first fluctuation component determination unit is used to obtain the electromagnetic torque twice stator frequency fluctuation component based on the electromagnetic torque through a bandpass filter of a first preset center frequency;

[0164] A second fluctuation component determination unit is used to obtain the electromagnetic torque double rotor frequency fluctuation component based on the electromagnetic torque through a bandpass filter of a second preset center frequency;

[0165] A third fluctuation component determination unit is used to obtain, based on the electromagnetic torque, a six-times stator frequency fluctuation component of the electromagnetic torque through a bandpass filter of a third preset center frequency;

[0166] The fourth fluctuation component determination unit is used to obtain the six-fold rotor frequency fluctuation component of the electromagnetic torque based on the electromagnetic torque through a bandpass filter with a fourth preset center frequency.

[0167] In an optional embodiment, the second fluctuation component determination submodule includes:

[0168] A stator reactive power determination unit, configured to calculate the stator reactive power based on the stator positive sequence voltage DC component and the stator positive sequence current DC component in combination with a reactive power calculation formula;

[0169] a fifth fluctuation component determination unit, configured to obtain, based on the stator reactive power, a fluctuation component of twice the stator frequency of the stator reactive power through a bandpass filter of the first preset center frequency;

[0170] a sixth fluctuation component determination unit, configured to obtain, based on the stator reactive power, a fluctuation component of twice the rotor frequency of the stator reactive power through a bandpass filter of the second preset center frequency;

[0171] a seventh fluctuation component determination unit, configured to obtain, based on the stator reactive power, a fluctuation component of six times the stator frequency through a bandpass filter of the third preset center frequency;

[0172] The eighth fluctuation component determination unit is used to obtain the stator reactive power six times rotor frequency fluctuation component based on the stator reactive power through a bandpass filter of the fourth preset center frequency.

[0173] In an optional embodiment, the electromagnetic torque calculation formula is specifically:

[0174]

[0175] Among them, T e is the electromagnetic torque, p n is the pole pair number, L m is the magnetizing inductance, and are the d-axis component and q-axis component of the stator positive sequence current respectively, and They are the d-axis component and q-axis component of the rotor positive sequence current respectively;

[0176] The reactive power calculation formula is specifically:

[0177]

[0178] Among them, Q s is the stator reactive power, and They are the d-axis component and q-axis component of the stator positive sequence voltage respectively.

[0179] In an optional embodiment, the first preset voltage control calculation formula is:

[0180]

[0181] Where s is the Laplace operator, and are the d-axis component and q-axis component of the positive sequence voltage reference value of the three-phase converter in series on the stator side, and are the reference value and actual value of the stator positive sequence q-axis current, respectively. and are the d-axis component and q-axis component of the stator side grid positive sequence voltage, respectively. and are the d-axis component and q-axis component of the stator positive sequence voltage, respectively, K p1 and K i1 are the proportional coefficient and integral coefficient of the stator reactive power controller, K p2 and K i2 are the proportional coefficient and integral coefficient of the stator q-axis voltage controller, respectively. and are the d-axis component and q-axis component of the negative sequence voltage reference value of the three-phase series converter on the stator side, T e2ωs is the electromagnetic torque twice the stator frequency fluctuation component, Q s2ωs K is the stator reactive power twice the stator frequency fluctuation component, p3 and K i3 are the proportional coefficient and integral coefficient of the electromagnetic torque twice stator frequency fluctuation component controller, K p4 and K i4 are the proportional coefficient and integral coefficient of the stator reactive power twice stator frequency fluctuation component controller, and are the d-axis component and q-axis component of the fifth harmonic voltage reference value of the three-phase series converter on the stator side, T e6ωs is the electromagnetic torque six times the stator frequency fluctuation component, Q s6ωs is the stator reactive power six times the stator frequency fluctuation component, K p5 and K i5 are the proportional coefficient and integral coefficient of the first electromagnetic torque six times stator frequency fluctuation component controller, K p6 and K i6 are the proportional coefficient and integral coefficient of the first stator reactive six times stator frequency fluctuation component controller, and are the d-axis component and q-axis component of the seventh harmonic voltage reference value of the three-phase converter in series on the stator side, K p7 and K i7 are the proportional coefficient and integral coefficient of the controller of the second electromagnetic torque six times the stator frequency fluctuation component, K p8 and K i8 They are respectively the proportional coefficient and integral coefficient of the second stator reactive power six times stator frequency fluctuation component controller.

[0182] In an optional embodiment, the second preset voltage control calculation formula is:

[0183]

[0184] in, and are the d-axis component and q-axis component of the positive sequence voltage reference value of the three-phase converter in series on the rotor side, and are the d-axis component and q-axis component of the rotor-side grid positive sequence voltage, respectively. and are the d-axis component and q-axis component of the rotor positive sequence voltage, respectively, K p9 and K i9 are the proportional coefficient and integral coefficient of the rotor d-axis voltage controller, K p10 and K i10 are the proportional coefficient and integral coefficient of the rotor q-axis voltage controller, respectively. and are the d-axis component and q-axis component of the negative sequence voltage reference value of the three-phase converter in series on the rotor side, T e2ωr is the electromagnetic torque twice the rotor frequency fluctuation component, Q s2ωr is the stator reactive power twice the rotor frequency fluctuation component, K p11 and K i11 are the proportional coefficient and integral coefficient of the electromagnetic torque double rotor frequency fluctuation component controller, K p12 and K i12 are the proportional coefficient and integral coefficient of the stator reactive power double rotor frequency fluctuation component controller, and are the d-axis component and q-axis component of the fifth harmonic voltage reference value of the three-phase converter in series on the rotor side, T e6ωr is the electromagnetic torque six times the rotor frequency fluctuation component, Q s6ωr is the stator reactive power six times the rotor frequency fluctuation component, K p13 and K i13 are the proportional coefficient and integral coefficient of the first electromagnetic torque six times rotor frequency fluctuation component controller, K p14 and K i14 are the proportional coefficient and integral coefficient of the first stator reactive six-times rotor frequency fluctuation component controller, and are the d-axis component and q-axis component of the seventh harmonic voltage reference value of the three-phase converter in series on the rotor side, K p15 and K i15 are the proportional coefficient and integral coefficient of the second electromagnetic torque six times rotor frequency fluctuation component controller, K p16 and K i16 They are respectively the proportional coefficient and integral coefficient of the second stator reactive six times rotor frequency fluctuation component controller.

[0185] In an optional embodiment, the first reference value determination module 302 includes:

[0186] The first reference value determination submodule is used to perform two-phase rotation to two-phase stationary coordinate transformation on the positive-sequence voltage reference value DC component of the stator-side series three-phase converter, the negative-sequence voltage reference value DC component of the stator-side series three-phase converter, the fifth harmonic voltage reference value DC component of the stator-side series three-phase converter, and the seventh harmonic voltage reference value DC component of the stator-side series three-phase converter, respectively, to obtain the positive-sequence voltage reference value of the stator-side series three-phase converter, the negative-sequence voltage reference value of the stator-side series three-phase converter, the fifth harmonic voltage reference value of the stator-side series three-phase converter, and the seventh harmonic voltage reference value of the stator-side series three-phase converter in a two-phase stator stationary coordinate system;

[0187] The second reference value determination submodule is used to use the sum of the positive sequence voltage reference value of the stator side series three-phase converter, the negative sequence voltage reference value of the stator side series three-phase converter, the fifth harmonic voltage reference value of the stator side series three-phase converter and the seventh harmonic voltage reference value of the stator side series three-phase converter as the voltage reference value of the stator side series three-phase converter.

[0188] In an optional embodiment, the second reference value determination module 402 includes:

[0189] The third reference value determination submodule is used to perform two-phase rotation to two-phase stationary coordinate transformation on the positive-sequence voltage reference value DC component of the rotor-side series three-phase converter, the negative-sequence voltage reference value DC component of the rotor-side series three-phase converter, the fifth harmonic voltage reference value DC component of the rotor-side series three-phase converter, and the seventh harmonic voltage reference value DC component of the rotor-side series three-phase converter, respectively, to obtain the positive-sequence voltage reference value of the rotor-side series three-phase converter, the negative-sequence voltage reference value of the rotor-side series three-phase converter, the fifth harmonic voltage reference value of the rotor-side series three-phase converter, and the seventh harmonic voltage reference value of the rotor-side series three-phase converter in a two-phase rotor rotating coordinate system;

[0190] The fourth reference value determination submodule is used to use the sum of the positive sequence voltage reference value of the rotor side series three-phase converter, the negative sequence voltage reference value of the rotor side series three-phase converter, the fifth harmonic voltage reference value of the rotor side series three-phase converter and the seventh harmonic voltage reference value of the rotor side series three-phase converter as the voltage reference value of the rotor side series three-phase converter in the two-phase rotor rotating coordinate system.

[0191] An embodiment of the present invention also provides an electronic device, including a memory and a processor, wherein the memory stores an analysis machine program, and when the analysis machine program is executed by the processor, the processor executes the steps of the variable frequency transformer torque and reactive power fluctuation suppression method as described in any of the above embodiments.

[0192] An embodiment of the present invention further provides an analysis machine readable storage medium on which an analysis machine program is stored. When the analysis machine program is executed by the processor, the method for suppressing torque and reactive power fluctuations of a variable frequency transformer as described in any of the above embodiments is implemented.

[0193] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0194] In the several embodiments provided in the present application, it should be understood that the methods, devices, electronic devices and storage media disclosed in the present invention can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0195] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0196] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0197] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium that can be read by an analyzer. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product. The analyzer software product is stored in a readable storage medium, including several instructions to enable an analyzer device (which can be a personal analyzer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned readable storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0198] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for suppressing torque and reactive power fluctuations of a variable frequency transformer, characterized in that: Applied to control systems, stator-side series three-phase converters and rotor-side series three-phase converters; The variable calculation method applied to the control system includes: Obtain the stator side grid voltage, stator voltage, rotor side grid voltage, rotor voltage, stator current, rotor current, pole pair number and excitation inductance; Based on the stator-side grid voltage, the stator voltage, the rotor-side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, a stator-side grid phase angle, a rotor-side grid phase angle, a stator-side grid positive-sequence voltage DC component, a stator positive-sequence voltage DC component, a rotor-side grid positive-sequence voltage DC component, a rotor positive-sequence voltage DC component, a stator positive-sequence current DC component, a rotor positive-sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power twice rotor frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component and a stator reactive power six times rotor frequency fluctuation component are obtained; The control method applied to the stator-side series three-phase converter comprises: Based on the phase angle of the stator-side power grid, the DC component of the stator-side power grid positive-sequence voltage, the DC component of the stator positive-sequence voltage, the DC component of the stator positive-sequence current, the electromagnetic torque twice the stator frequency fluctuation component, the electromagnetic torque six times the stator frequency fluctuation component, the stator reactive power twice the stator frequency fluctuation component, and the stator reactive power six times the stator frequency fluctuation component, in combination with a first preset voltage control calculation formula, a DC component of a positive-sequence voltage reference value of a stator-side series three-phase converter, a DC component of a negative-sequence voltage reference value of a stator-side series three-phase converter, a DC component of a fifth harmonic voltage reference value of a stator-side series three-phase converter, and a DC component of a seventh harmonic voltage reference value of a stator-side series three-phase converter are calculated; Determine the voltage reference value of the stator side series three-phase converter in a two-phase stator stationary coordinate system according to the DC component of the positive sequence voltage reference value of the stator side series three-phase converter, the DC component of the negative sequence voltage reference value of the stator side series three-phase converter, the DC component of the fifth harmonic voltage reference value of the stator side series three-phase converter, and the DC component of the seventh harmonic voltage reference value of the stator side series three-phase converter; By performing space vector modulation on the voltage reference value of the stator-side series three-phase converter, a control signal of the stator-side series three-phase converter switch is obtained; the control signal of the stator-side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced voltage and harmonic distortion of the stator-side power grid; The control method applied to the rotor-side series three-phase converter comprises: Based on the rotor-side grid phase angle, the rotor-side grid positive-sequence voltage DC component, the rotor positive-sequence voltage DC component, the electromagnetic torque twice the rotor frequency fluctuation component, the electromagnetic torque six times the rotor frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component, in combination with a second preset voltage control calculation formula, a rotor-side series three-phase converter positive-sequence voltage reference value DC component, a rotor-side series three-phase converter negative-sequence voltage reference value DC component, a rotor-side series three-phase converter fifth harmonic voltage reference value DC component and a rotor-side series three-phase converter seventh harmonic voltage reference value DC component are calculated; Determine the voltage reference value of the rotor side series three-phase converter in a two-phase rotor rotating coordinate system according to the DC component of the positive sequence voltage reference value of the rotor side series three-phase converter, the DC component of the negative sequence voltage reference value of the rotor side series three-phase converter, the DC component of the fifth harmonic voltage reference value of the rotor side series three-phase converter, and the DC component of the seventh harmonic voltage reference value of the rotor side series three-phase converter; By performing space vector modulation on the voltage reference value of the three-phase converter in series on the rotor side, a control signal of the three-phase converter switch in series on the rotor side is obtained; the control signal of the three-phase converter switch in series on the rotor side is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced voltage and harmonic distortion of the rotor side grid.

2. The variable frequency transformer torque and reactive power fluctuation suppression method according to claim 1, characterized in that: Based on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, a stator side grid phase angle, a rotor side grid phase angle, a stator side grid positive sequence voltage DC component, a stator positive sequence voltage DC component, a rotor side grid positive sequence voltage DC component, a rotor positive sequence voltage DC component, a stator positive sequence current DC component, a rotor positive sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power twice rotor frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component and a stator reactive power six times rotor frequency fluctuation component are obtained, including: The stator side grid voltage and the rotor side grid voltage are processed respectively by a digital phase-locked loop to obtain the stator side grid phase angle and the rotor side grid phase angle; Based on the stator side grid phase angle and the rotor side grid phase angle, coordinate transformation is performed on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current and the rotor current to obtain the stator side grid positive sequence voltage DC component, the stator positive sequence voltage DC component, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the stator positive sequence current DC component and the rotor positive sequence current DC component.

3. The variable frequency transformer torque and reactive power fluctuation suppression method according to claim 2, characterized in that: Based on the stator-side grid voltage, the stator voltage, the rotor-side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, a stator-side grid phase angle, a rotor-side grid phase angle, a stator-side grid positive-sequence voltage DC component, a stator positive-sequence voltage DC component, a rotor-side grid positive-sequence voltage DC component, a rotor positive-sequence voltage DC component, a stator positive-sequence current DC component, a rotor positive-sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power twice rotor frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component and a stator reactive power six times rotor frequency fluctuation component are obtained, and further comprising: Based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance, the electromagnetic torque twice stator frequency fluctuation component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times stator frequency fluctuation component and the electromagnetic torque six times rotor frequency fluctuation component are obtained; Based on the stator positive-sequence voltage DC component and the stator positive-sequence current DC component, the stator reactive power twice the stator frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, the stator reactive power six times the stator frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component are obtained.

4. The method for suppressing torque and reactive power fluctuations of a variable frequency transformer according to claim 2, characterized in that: Based on the stator side grid phase angle and the rotor side grid phase angle, coordinate transformation is performed on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current, and the rotor current to obtain the stator side grid positive sequence voltage DC component, the stator positive sequence voltage DC component, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the stator positive sequence current DC component, and the rotor positive sequence current DC component, including: Based on the phase angle of the stator-side power grid, the stator voltage and the stator current are transformed from three-phase static to two-phase rotating coordinates to obtain the stator-side power grid positive-sequence voltage DC component, the stator positive-sequence voltage DC component and the stator positive-sequence current DC component; Based on the rotor-side grid phase angle, the rotor-side grid voltage, the rotor voltage and the rotor current are transformed from three-phase static to two-phase rotating coordinates to obtain the rotor-side grid positive-sequence voltage DC component, the rotor positive-sequence voltage DC component and the rotor positive-sequence current DC component.

5. The variable frequency transformer torque and reactive power fluctuation suppression method according to claim 3, characterized in that: Based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance, the electromagnetic torque twice stator frequency fluctuation component, the electromagnetic torque twice rotor frequency fluctuation component, the electromagnetic torque six times stator frequency fluctuation component and the electromagnetic torque six times rotor frequency fluctuation component are obtained, including: The electromagnetic torque is calculated based on the stator positive sequence current DC component, the rotor positive sequence current DC component, the pole pair number and the excitation inductance in combination with an electromagnetic torque calculation formula; Based on the electromagnetic torque, a double stator frequency fluctuation component of the electromagnetic torque is obtained by passing it through a bandpass filter of a first preset center frequency; Based on the electromagnetic torque, a double rotor frequency fluctuation component of the electromagnetic torque is obtained through a bandpass filter of a second preset center frequency; Based on the electromagnetic torque, a six-fold stator frequency fluctuation component of the electromagnetic torque is obtained by passing it through a bandpass filter of a third preset center frequency; Based on the electromagnetic torque, a six-fold rotor frequency fluctuation component of the electromagnetic torque is obtained through a bandpass filter with a fourth preset center frequency.

6. The variable frequency transformer torque and reactive power fluctuation suppression method according to claim 5, characterized in that: Based on the stator positive sequence voltage DC component and the stator positive sequence current DC component, the stator reactive power twice the stator frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, the stator reactive power six times the stator frequency fluctuation component and the stator reactive power six times the rotor frequency fluctuation component are obtained, including: Based on the stator positive sequence voltage DC component and the stator positive sequence current DC component, in combination with the stator reactive power calculation formula, the stator reactive power is calculated; Based on the stator reactive power, a stator reactive power fluctuation component of twice the stator frequency is obtained by passing the stator reactive power through a bandpass filter of the first preset center frequency; Based on the stator reactive power, a twice rotor frequency fluctuation component of the stator reactive power is obtained through a bandpass filter of the second preset center frequency; Based on the stator reactive power, a six-fold stator frequency fluctuation component of the stator reactive power is obtained through a bandpass filter of the third preset center frequency; Based on the stator reactive power, the stator reactive power six times rotor frequency fluctuation component is obtained through the bandpass filter of the fourth preset center frequency.

7. The variable frequency transformer torque and reactive power fluctuation suppression method according to claim 6, characterized in that: The electromagnetic torque calculation formula is specifically: Among them, T e is the electromagnetic torque, p n is the pole pair number, L m is the magnetizing inductance, and are the d-axis component and q-axis component of the stator positive sequence current respectively, and They are the d-axis component and q-axis component of the rotor positive sequence current respectively; The stator reactive power calculation formula is specifically: Among them, Q s is the stator reactive power, and They are the d-axis component and q-axis component of the stator positive sequence voltage respectively.

8. The variable frequency transformer torque and reactive power fluctuation suppression method according to claim 1, characterized in that: The first preset voltage control calculation formula is: Where s is the Laplace operator, and are the d-axis component and q-axis component of the positive sequence voltage reference value of the three-phase converter in series on the stator side, and are the reference value and actual value of the stator positive sequence q-axis current, respectively. and are the d-axis component and q-axis component of the stator side grid positive sequence voltage, respectively. and are the d-axis component and q-axis component of the stator positive sequence voltage, respectively, K p1 and K i1 are the proportional coefficient and integral coefficient of the stator reactive power controller, K p2 and K i2 are the proportional coefficient and integral coefficient of the stator q-axis voltage controller, respectively. and are the d-axis component and q-axis component of the negative sequence voltage reference value of the three-phase series converter on the stator side, T e2ωs is the electromagnetic torque twice the stator frequency fluctuation component, Q s2ωs K is the stator reactive power twice the stator frequency fluctuation component, p3 and K i3 are the proportional coefficient and integral coefficient of the electromagnetic torque twice stator frequency fluctuation component controller, K p4 and K i4 are the proportional coefficient and integral coefficient of the stator reactive power twice stator frequency fluctuation component controller, and are the d-axis component and q-axis component of the fifth harmonic voltage reference value of the three-phase series converter on the stator side, T e6ωs is the electromagnetic torque six times the stator frequency fluctuation component, Q s6ωs is the stator reactive power six times the stator frequency fluctuation component, K p5 and K i5 are the proportional coefficient and integral coefficient of the first electromagnetic torque six times stator frequency fluctuation component controller, K p6 and K i6 are the proportional coefficient and integral coefficient of the first stator reactive six times stator frequency fluctuation component controller, and are the d-axis component and q-axis component of the seventh harmonic voltage reference value of the three-phase converter in series on the stator side, K p7 and K i7 are the proportional coefficient and integral coefficient of the controller of the second electromagnetic torque six times the stator frequency fluctuation component, K p8 and K i8 They are respectively the proportional coefficient and integral coefficient of the second stator reactive power six times stator frequency fluctuation component controller.

9. The method for suppressing torque and reactive power fluctuations of a variable frequency transformer according to claim 8, characterized in that: The second preset voltage control calculation formula is: in, and are the d-axis component and q-axis component of the positive sequence voltage reference value of the three-phase converter in series on the rotor side, and are the d-axis component and q-axis component of the rotor-side grid positive sequence voltage, respectively. and are the d-axis component and q-axis component of the rotor positive sequence voltage, respectively, K p9 and K i9 are the proportional coefficient and integral coefficient of the rotor d-axis voltage controller, K p10 and K i10 are the proportional coefficient and integral coefficient of the rotor q-axis voltage controller, respectively. and are the d-axis component and q-axis component of the negative sequence voltage reference value of the three-phase converter in series on the rotor side, T e2ωr is the electromagnetic torque twice the rotor frequency fluctuation component, Q s2ωr is the stator reactive power twice the rotor frequency fluctuation component, K p11 and K i11 are the proportional coefficient and integral coefficient of the electromagnetic torque double rotor frequency fluctuation component controller, K p12 and K i12 are the proportional coefficient and integral coefficient of the stator reactive power double rotor frequency fluctuation component controller, and are the d-axis component and q-axis component of the fifth harmonic voltage reference value of the three-phase converter in series on the rotor side, T e6ωr is the electromagnetic torque six times the rotor frequency fluctuation component, Q s6ωr is the stator reactive power six times the rotor frequency fluctuation component, K p13 and K i13 are the proportional coefficient and integral coefficient of the first electromagnetic torque six times rotor frequency fluctuation component controller, K p14 and K i14 are the proportional coefficient and integral coefficient of the first stator reactive six-times rotor frequency fluctuation component controller, and are the d-axis component and q-axis component of the seventh harmonic voltage reference value of the three-phase converter in series on the rotor side, K p15 and K i15 are the proportional coefficient and integral coefficient of the second electromagnetic torque six times rotor frequency fluctuation component controller, K p16 and K i16 They are respectively the proportional coefficient and integral coefficient of the second stator reactive six times rotor frequency fluctuation component controller.

10. The variable frequency transformer torque and reactive power fluctuation suppression method according to claim 1, characterized in that: Determining the voltage reference value of the stator side series three-phase converter in a two-phase stator stationary coordinate system according to the DC component of the positive sequence voltage reference value of the stator side series three-phase converter, the DC component of the negative sequence voltage reference value of the stator side series three-phase converter, the DC component of the fifth harmonic voltage reference value of the stator side series three-phase converter, and the DC component of the seventh harmonic voltage reference value of the stator side series three-phase converter, includes: Respectively perform two-phase rotation to two-phase stationary coordinate transformation on the positive-sequence voltage reference value DC component of the stator-side series three-phase converter, the negative-sequence voltage reference value DC component of the stator-side series three-phase converter, the fifth-order harmonic voltage reference value DC component of the stator-side series three-phase converter, and the seventh-order harmonic voltage reference value DC component of the stator-side series three-phase converter, to obtain the positive-sequence voltage reference value of the stator-side series three-phase converter, the negative-sequence voltage reference value of the stator-side series three-phase converter, the fifth-order harmonic voltage reference value of the stator-side series three-phase converter, and the seventh-order harmonic voltage reference value of the stator-side series three-phase converter in a two-phase stator stationary coordinate system; The sum of the positive sequence voltage reference value of the stator side series three-phase converter, the negative sequence voltage reference value of the stator side series three-phase converter, the fifth harmonic voltage reference value of the stator side series three-phase converter and the seventh harmonic voltage reference value of the stator side series three-phase converter is used as the voltage reference value of the stator side series three-phase converter.

11. The method for suppressing torque and reactive power fluctuations of a variable frequency transformer according to claim 1, characterized in that: Determining the voltage reference value of the rotor side series three-phase converter in a two-phase rotor rotating coordinate system according to the positive sequence voltage reference value DC component of the rotor side series three-phase converter, the negative sequence voltage reference value DC component of the rotor side series three-phase converter, the fifth harmonic voltage reference value DC component of the rotor side series three-phase converter, and the seventh harmonic voltage reference value DC component of the rotor side series three-phase converter, includes: Respectively perform two-phase rotation to two-phase stationary coordinate transformation on the positive-sequence voltage reference value DC component of the rotor-side series three-phase converter, the negative-sequence voltage reference value DC component of the rotor-side series three-phase converter, the fifth-order harmonic voltage reference value DC component of the rotor-side series three-phase converter, and the seventh-order harmonic voltage reference value DC component of the rotor-side series three-phase converter, to obtain the positive-sequence voltage reference value of the rotor-side series three-phase converter, the negative-sequence voltage reference value of the rotor-side series three-phase converter, the fifth-order harmonic voltage reference value of the rotor-side series three-phase converter, and the seventh-order harmonic voltage reference value of the rotor-side series three-phase converter in a two-phase rotor rotating coordinate system; The sum of the positive sequence voltage reference value of the rotor side series three-phase converter, the negative sequence voltage reference value of the rotor side series three-phase converter, the fifth harmonic voltage reference value of the rotor side series three-phase converter and the seventh harmonic voltage reference value of the rotor side series three-phase converter is used as the voltage reference value of the rotor side series three-phase converter in the two-phase rotor rotating coordinate system.

12. A variable frequency transformer torque and reactive power fluctuation suppression device, characterized in that: include: A variable calculation device used in a control system, comprising: A first acquisition module is used to acquire a stator side grid voltage, a stator voltage, a rotor side grid voltage, a rotor voltage, a stator current, a rotor current, a pole pair number and an excitation inductance; a parameter determination module, for obtaining, based on the stator side grid voltage, the stator voltage, the rotor side grid voltage, the rotor voltage, the stator current, the rotor current, the pole pair number and the excitation inductance, a stator side grid phase angle, a rotor side grid phase angle, a stator side grid positive sequence voltage DC component, a stator positive sequence voltage DC component, a rotor side grid positive sequence voltage DC component, a rotor positive sequence voltage DC component, a stator positive sequence current DC component, a rotor positive sequence current DC component, an electromagnetic torque twice stator frequency fluctuation component, an electromagnetic torque twice rotor frequency fluctuation component, an electromagnetic torque six times stator frequency fluctuation component, an electromagnetic torque six times rotor frequency fluctuation component, a stator reactive power twice stator frequency fluctuation component, a stator reactive power twice rotor frequency fluctuation component, a stator reactive power six times stator frequency fluctuation component and a stator reactive power six times rotor frequency fluctuation component; A control device for a stator-side series three-phase converter, comprising: A first parameter determination module is used to calculate the positive sequence voltage reference value DC component of the stator side series three-phase converter, the negative sequence voltage reference value DC component of the stator side series three-phase converter, the fifth harmonic voltage reference value DC component of the stator side series three-phase converter, and the seventh harmonic voltage reference value DC component of the stator side series three-phase converter based on the phase angle of the stator side power grid, the positive sequence voltage DC component of the stator side power grid, the stator positive sequence voltage DC component, the stator positive sequence current DC component, the electromagnetic torque twice the stator frequency fluctuation component, the electromagnetic torque six times the stator frequency fluctuation component, the stator reactive power twice the stator frequency fluctuation component, and the stator reactive power six times the stator frequency fluctuation component, in combination with a first preset voltage control calculation formula; A first reference value determination module is used to determine the stator side series three-phase converter voltage reference value in a two-phase stator stationary coordinate system according to the stator side series three-phase converter positive sequence voltage reference value DC component, the stator side series three-phase converter negative sequence voltage reference value DC component, the stator side series three-phase converter fifth harmonic voltage reference value DC component and the stator side series three-phase converter seventh harmonic voltage reference value DC component; A first control signal determination module is used to obtain a control signal of a stator-side series three-phase converter switch by performing space vector modulation on the stator-side series three-phase converter voltage reference value; the control signal of the stator-side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced stator-side grid voltage and harmonic distortion; A control device for a rotor-side series three-phase converter, comprising: A second parameter determination module is used to calculate the positive sequence voltage reference value DC component of the rotor side series three-phase converter, the negative sequence voltage reference value DC component of the rotor side series three-phase converter, the fifth harmonic voltage reference value DC component of the rotor side series three-phase converter, and the seventh harmonic voltage reference value DC component of the rotor side series three-phase converter based on the rotor side grid phase angle, the rotor side grid positive sequence voltage DC component, the rotor positive sequence voltage DC component, the electromagnetic torque twice the rotor frequency fluctuation component, the electromagnetic torque six times the rotor frequency fluctuation component, the stator reactive power twice the rotor frequency fluctuation component, and the stator reactive power six times the rotor frequency fluctuation component, in combination with a second preset voltage control calculation formula; A second reference value determination module is used to determine the rotor side series three-phase converter voltage reference value in a two-phase rotor rotating coordinate system according to the rotor side series three-phase converter positive sequence voltage reference value DC component, the rotor side series three-phase converter negative sequence voltage reference value DC component, the rotor side series three-phase converter fifth harmonic voltage reference value DC component and the rotor side series three-phase converter seventh harmonic voltage reference value DC component; The second control signal determination module is used to obtain a control signal of the rotor side series three-phase converter switch by performing space vector modulation on the rotor side series three-phase converter voltage reference value; the control signal of the rotor side series three-phase converter switch is used to suppress the fluctuation of the electromagnetic torque and stator reactive power of the variable frequency transformer caused by the unbalanced rotor side grid voltage and harmonic distortion.

13. An electronic device, characterized in that: The method comprises a processor and a memory, wherein the memory stores computer-readable instructions, and when the computer-readable instructions are executed by the processor, the method according to any one of claims 1 to 11 is executed.

14. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, the method according to any one of claims 1 to 11 is executed.

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