A variable frequency transformer fault ride-through control method and related device for comprehensive regulation of grid voltage

Abstract

This application relates to the field of power grid control and discloses a variable frequency transformer fault ride-through control method and related device for comprehensively regulating power grid voltage. The method is applied to a fault ride-through circuit, collects stator winding parameters, three-phase converter parameters, capacitor voltage, and rotor phase angle; calculates stator winding reactive power, three-phase converter positive-sequence current, and stator winding DC component based on the collected parameters; analyzes the data based on the voltage control equation to obtain the DC component of the three-phase converter's positive and negative sequence voltage reference values ​​and odd harmonic voltage reference values; analyzes the DC component of the three-phase converter's positive and negative sequence voltage reference values ​​and the three-phase converter's odd harmonic voltage reference values ​​based on the grid voltage phase angle and rotor phase angle to obtain the three-phase converter voltage vector reference value; and performs space vector modulation on the voltage vector reference value. This method addresses the current technical problem of requiring at least two three-phase converters to achieve voltage imbalance and harmonic distortion fault ride-through control, which results in high material consumption and complex operation.

Description

Technical Field

[0001] The present application relates to the field of power grid control technology, and in particular to a variable frequency transformer fault ride-through control method and related devices for comprehensively regulating power grid voltage. Background Art

[0002] The power grid is a crucial backbone of the Energy Internet, and grid interconnection will be an inevitable trend in future grid development. A variable frequency transformer (VFT) is a new type of grid interconnection device. When the grid voltages on both sides of a VFT are unbalanced and harmonically distorted, the current flowing through the VFT will also be unbalanced and harmonically distorted. The interaction between these unbalanced and harmonically distorted voltages and currents can cause the VFT's electromagnetic torque, active power, and reactive power to fluctuate in the following ranges: twice the rotor's electrical angular velocity, six times the rotor's electrical angular velocity, twice the stator's synchronous angular velocity, twice the rotor's synchronous angular velocity, six times the stator's synchronous angular velocity minus twice the rotor's synchronous angular velocity, four times the stator's synchronous angular velocity, six times the rotor's synchronous angular velocity minus twice the stator's synchronous angular velocity, six times the stator's synchronous angular velocity, six times the rotor's synchronous angular velocity, eight times the stator's synchronous angular velocity, six times the stator's synchronous angular velocity plus twice the rotor's synchronous angular velocity, two times the stator's synchronous angular velocity plus six times the rotor's synchronous angular velocity, twelve times the stator's synchronous angular velocity, and six times the stator's synchronous angular velocity plus six times the rotor's synchronous angular velocity. Torque fluctuations will reduce the mechanical life of the shaft, and power fluctuations will reduce the power quality of the power system.

[0003] Existing technologies usually require the use of at least two three-phase converters to stabilize the DC capacitor voltage and solve the problems of unbalanced voltage and harmonic distortion on both sides of the power grid. From the perspective of consumables cost, this will undoubtedly consume more materials and be more expensive. From the perspective of the operation process, too many devices will increase the complexity of operation, reduce the actual control efficiency, and be unfavorable for application in actual scenarios. Summary of the Invention

[0004] The present application provides a variable frequency transformer fault ride-through control method and related devices for comprehensively regulating grid voltage, which are used to solve the technical problems that the existing technology requires at least two three-phase converters to achieve grid voltage imbalance and harmonic distortion fault ride-through regulation and control, and has obvious technical problems of large consumables and complex operation.

[0005] In view of this, a first aspect of the present application provides a variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage, wherein the control method is applied to a variable frequency transformer fault ride-through circuit, the circuit comprising: a first grid, a second grid, a three-phase transformer, a three-phase converter, a variable frequency transformer, an H-bridge converter, a DC capacitor, and a control circuit;

[0006] One end of the AC output terminal of the three-phase transformer is connected to the first power grid, and the other end is connected to the stator winding of the variable frequency transformer;

[0007] The rotor winding of the variable frequency transformer is connected to the second power grid;

[0008] The AC input terminal of the three-phase transformer is connected to the AC terminal of the three-phase converter;

[0009] The DC end of the three-phase converter is connected to the DC input end of the H-bridge converter and the DC capacitor;

[0010] The DC output terminal of the H-bridge converter is connected to the DC motor of the variable frequency transformer;

[0011] The control circuit is connected to the control signal input terminals of the three-phase converter and the H-bridge converter respectively;

[0012] The control method includes:

[0013] Collecting grid voltage, stator winding parameters, three-phase converter parameters, capacitor voltage, and rotor phase angle, wherein the grid voltage includes the voltage of the first grid and the second grid, and the stator winding parameters and the three-phase converter parameters both include voltage and current;

[0014] Analyzing and processing the grid voltage, the stator winding parameters, the three-phase converter parameters, and the rotor phase angle to obtain stator winding reactive power, a three-phase converter positive-sequence current DC component, a stator winding negative-sequence DC component, and a plurality of stator winding odd harmonic DC components;

[0015] Analyzing the capacitor voltage, the stator winding reactive power, the three-phase converter positive-sequence current DC component, the stator winding negative-sequence DC component, and the stator winding odd-numbered harmonic DC component based on a preset voltage control equation to obtain a three-phase converter positive- and negative-sequence voltage reference value DC component and a plurality of three-phase converter odd-numbered harmonic voltage reference value DC components;

[0016] Analyzing the DC components of the positive and negative sequence voltage reference values ​​and the DC components of the odd harmonic voltage reference values ​​of the three-phase converter according to the grid voltage phase angle and the rotor phase angle to obtain a voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0017] The three-phase converter voltage vector reference value is subjected to space vector modulation to generate a control signal for the three-phase converter switch, and variable frequency transformer fault ride-through control is implemented based on the control signal.

[0018] Preferably, the analyzing and processing of the grid voltage, the stator winding parameters, the three-phase converter parameters, and the rotor phase angle to obtain the stator winding reactive power, the three-phase converter positive-sequence current DC component, the stator winding negative-sequence DC component, and a plurality of stator winding odd-numbered harmonic DC components includes:

[0019] Performing power calculation according to the stator winding parameters to obtain the stator winding reactive power;

[0020] Performing phase-locked loop processing on the grid voltage and the voltage parameters of the three-phase converter parameters to obtain a grid voltage phase angle and a three-phase converter voltage phase angle;

[0021] Performing a three-phase stationary to two-phase rotating coordinate transformation on the current parameters of the three-phase converter parameters according to the voltage phase angle of the three-phase converter to obtain a DC component of the positive sequence current of the three-phase converter;

[0022] The stator winding parameters are subjected to three-phase stationary to two-phase rotating coordinate transformation and notch filter filtering according to the grid voltage phase angle and the rotor phase angle to obtain a stator winding negative sequence DC component and a plurality of stator winding odd harmonic DC components.

[0023] Preferably, performing three-phase stationary to two-phase rotating coordinate transformation and notch filter filtering on the stator winding parameters according to the grid voltage phase angle and the rotor phase angle to obtain a stator winding negative-sequence DC component and a plurality of stator winding odd harmonic DC components includes:

[0024] Performing a three-phase stationary to two-phase rotating coordinate transformation and a notch filter filtering process of a first preset frequency on the voltage parameters of the stator winding parameters according to the grid voltage phase angle, to obtain a stator winding negative sequence voltage DC component and two stator winding odd harmonic voltage DC components;

[0025] According to the grid voltage phase angle, the current parameters of the stator winding parameters are transformed from three-phase static to two-phase rotating coordinates and filtered by a notch filter of a second preset frequency to obtain a stator winding negative sequence current DC component and two stator winding odd harmonic current DC components.

[0026] Preferably, the analyzing the DC components of the positive and negative sequence voltage reference values ​​and the DC components of the odd harmonic voltage reference values ​​of the three-phase converter according to the grid voltage phase angle and the rotor phase angle to obtain the voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system includes:

[0027] Performing a two-phase rotation to a two-phase stationary coordinate transformation on the positive-sequence component of the DC component of the positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a positive-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0028] Performing a two-phase rotation to a two-phase stationary coordinate transformation on a first negative-sequence component of a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a first negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0029] Performing a two-phase rotation to two-phase stationary coordinate transformation on the DC component of the odd harmonic voltage reference value of the three-phase converter according to the grid voltage phase angle, to obtain a first harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0030] performing a two-phase rotation to two-phase stationary coordinate transformation process on a second negative-sequence component of a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a second negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0031] Performing a two-phase rotation to two-phase stationary coordinate transformation on the DC component of the odd harmonic voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a second harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0032] The three-phase converter positive-sequence voltage vector reference value, the three-phase converter first negative-sequence voltage vector reference value, the three-phase converter first harmonic voltage vector reference value, the three-phase converter second negative-sequence voltage vector reference value, and the three-phase converter second harmonic voltage vector reference value are summed to obtain a three-phase converter voltage vector reference value in a two-phase stationary coordinate system.

[0033] A second aspect of the present application provides a variable frequency transformer fault ride-through control device for comprehensively regulating grid voltage, wherein the control device is applied to a variable frequency transformer fault ride-through circuit, the circuit comprising: a first grid, a second grid, a three-phase transformer, a three-phase converter, a variable frequency transformer, an H-bridge converter, a DC capacitor, and a control circuit;

[0034] One end of the AC output terminal of the three-phase transformer is connected to the first power grid, and the other end is connected to the stator winding of the variable frequency transformer;

[0035] The rotor winding of the variable frequency transformer is connected to the second power grid;

[0036] The AC input terminal of the three-phase transformer is connected to the AC terminal of the three-phase converter;

[0037] The DC end of the three-phase converter is connected to the DC input end of the H-bridge converter and the DC capacitor;

[0038] The DC output terminal of the H-bridge converter is connected to the DC motor of the variable frequency transformer;

[0039] The control circuit is connected to the control signal input terminals of the three-phase converter and the H-bridge converter respectively;

[0040] The control device comprises:

[0041] a parameter acquisition unit, configured to acquire grid voltage, stator winding parameters, three-phase converter parameters, capacitor voltage, and rotor phase angle, wherein the grid voltage includes the voltage of the first grid and the second grid, and the stator winding parameters and the three-phase converter parameters both include voltage and current;

[0042] a first analyzing unit, configured to analyze and process the grid voltage, the stator winding parameters, the three-phase converter parameters, and the rotor phase angle to obtain stator winding reactive power, a three-phase converter positive-sequence current DC component, a stator winding negative-sequence DC component, and a plurality of stator winding odd harmonic DC components;

[0043] a second analyzing unit, configured to analyze the capacitor voltage, the stator winding reactive power, the positive-sequence DC component of the three-phase converter current, the negative-sequence DC component of the stator winding, and the odd-numbered harmonic DC component of the stator winding based on a preset voltage control equation, to obtain a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter and a plurality of DC components of an odd-numbered harmonic voltage reference value of the three-phase converter;

[0044] a third analyzing unit, configured to analyze the DC components of the positive and negative sequence voltage reference values ​​and the DC components of the odd harmonic voltage reference values ​​of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0045] A modulation control unit is used to perform space vector modulation on the three-phase converter voltage vector reference value to generate a control signal for the three-phase converter switch, and implement variable frequency transformer fault ride-through control based on the control signal.

[0046] Preferably, the first analysis unit specifically includes:

[0047] A power calculation subunit, configured to perform power calculation based on the stator winding parameters to obtain the stator winding reactive power;

[0048] a phase angle calculation subunit, configured to perform phase-locked loop processing on the grid voltage and the voltage parameters of the three-phase converter parameters, respectively, to obtain a grid voltage phase angle and a three-phase converter voltage phase angle;

[0049] A positive sequence analysis subunit, configured to perform a three-phase stationary to two-phase rotating coordinate transformation on the current parameters of the three-phase converter parameters according to the voltage phase angle of the three-phase converter, to obtain a DC component of the positive sequence current of the three-phase converter;

[0050] The harmonic analysis subunit is used to perform three-phase static to two-phase rotating coordinate transformation and notch filter filtering on the stator winding parameters according to the grid voltage phase angle and the rotor phase angle, so as to obtain the stator winding negative sequence DC component and multiple stator winding odd harmonic DC components.

[0051] Preferably, the harmonic analysis subunit is specifically used to:

[0052] Performing a three-phase stationary to two-phase rotating coordinate transformation and a notch filter filtering process of a first preset frequency on the voltage parameters of the stator winding parameters according to the grid voltage phase angle, to obtain a stator winding negative sequence voltage DC component and two stator winding odd harmonic voltage DC components;

[0053] According to the grid voltage phase angle, the current parameters of the stator winding parameters are transformed from three-phase static to two-phase rotating coordinates and filtered by a notch filter of a second preset frequency to obtain a stator winding negative sequence current DC component and two stator winding odd harmonic current DC components.

[0054] Preferably, the third analysis unit is specifically used to:

[0055] Performing a two-phase rotation to a two-phase stationary coordinate transformation on the positive-sequence component of the DC component of the positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a positive-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0056] Performing a two-phase rotation to a two-phase stationary coordinate transformation on a first negative-sequence component of a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a first negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0057] Performing a two-phase rotation to two-phase stationary coordinate transformation on the DC component of the odd harmonic voltage reference value of the three-phase converter according to the grid voltage phase angle, to obtain a first harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0058] performing a two-phase rotation to two-phase stationary coordinate transformation process on a second negative-sequence component of a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a second negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0059] Performing a two-phase rotation to two-phase stationary coordinate transformation on the DC component of the odd harmonic voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a second harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0060] The three-phase converter positive-sequence voltage vector reference value, the three-phase converter first negative-sequence voltage vector reference value, the three-phase converter first harmonic voltage vector reference value, the three-phase converter second negative-sequence voltage vector reference value, and the three-phase converter second harmonic voltage vector reference value are summed to obtain a three-phase converter voltage vector reference value in a two-phase stationary coordinate system.

[0061] A third aspect of the present application provides a variable frequency transformer fault ride-through control device for comprehensively regulating grid voltage, the device comprising a processor and a memory;

[0062] The memory is used to store program code and transmit the program code to the processor;

[0063] The processor is used to execute the variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage according to the instructions in the program code described in the first aspect.

[0064] In a fourth aspect, the present application provides a computer-readable storage medium for storing program code, wherein the program code is used to execute the variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage as described in the first aspect.

[0065] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0066] In the present application, a variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage is provided. The control method is applied in a variable frequency transformer fault ride-through circuit, and the circuit includes: a first grid, a second grid, a three-phase transformer, a three-phase converter, a variable frequency transformer, an H-bridge converter, a DC capacitor and a control circuit; one end of the AC output end of the three-phase transformer is connected to the first grid, and the other end is connected to the stator winding of the variable frequency transformer; the rotor winding of the variable frequency transformer is connected to the second grid; the AC input end of the three-phase transformer is connected to the AC end of the three-phase converter; the DC end of the three-phase converter is connected to the DC input end and the DC capacitor of the H-bridge converter; the DC output end of the H-bridge converter is connected to the DC motor of the variable frequency transformer; and the control circuit is respectively connected to the control signal input ends of the three-phase converter and the H-bridge converter.

[0067] Control methods include:

[0068] Collect grid voltage, stator winding parameters, three-phase converter parameters, capacitor voltage and rotor phase angle, the grid voltage includes the voltage of the first grid and the second grid, the stator winding parameters and the three-phase converter parameters include voltage and current; analyze and process the grid voltage, stator winding parameters, three-phase converter parameters and rotor phase angle to obtain stator winding reactive power, three-phase converter positive sequence current DC component, stator winding negative sequence DC component and multiple stator winding odd harmonic DC components; based on the preset voltage control equation, the capacitor voltage, stator winding reactive power, three-phase converter positive sequence current DC component, stator winding negative sequence DC component and multiple stator winding odd harmonic DC components are obtained. The positive-sequence DC components and the odd-harmonic DC components of the stator winding are analyzed to obtain the DC components of the positive-negative sequence voltage reference values ​​of the three-phase converter and the DC components of multiple odd-harmonic voltage reference values ​​of the three-phase converter; the positive-negative sequence DC components and the DC components of the odd-harmonic voltage reference values ​​of the three-phase converter are analyzed according to the grid voltage phase angle and the rotor phase angle to obtain the voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; the voltage vector reference value of the three-phase converter is space-vector modulated to generate a control signal for the three-phase converter switch, and the fault ride-through control of the variable frequency transformer is realized based on the control signal.

[0069] The present application provides a variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage, which is applied to a variable frequency transformer fault ride-through circuit. This fault ride-through circuit only requires a three-phase converter in series to simultaneously solve the DC capacitor voltage control problem and the problem of unbalanced grid voltage and harmonic distortion on both sides. Based on this circuit, a detailed and clear fault ride-through control method is designed. It can still accurately calculate the control signal without relying on more three-phase converters. While ensuring the reliability of the variable frequency transformer ride-through control, it can also reduce circuit complexity, avoid large consumables and more complex operations, and meet actual fault ride-through control requirements. Therefore, the present application can solve the technical problem that the existing technology requires at least two three-phase converters to achieve the regulation and control of grid voltage imbalance and harmonic distortion fault ride-through, which has obvious large consumables and complex operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 A schematic diagram of an application scenario of a variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage provided in an embodiment of the present application;

[0071] Figure 2 A flow chart of a variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage provided in an embodiment of the present application;

[0072] Figure 3 A schematic diagram of the overall calculation and analysis process of the variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage provided in an embodiment of the present application;

[0073] Figure 4 A schematic structural diagram of a variable frequency transformer fault ride-through control device for comprehensively regulating grid voltage provided in an embodiment of the present application. DETAILED DESCRIPTION

[0074] In order to help those skilled in the art better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments 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 those skilled in the art without creative work are within the scope of protection of this application.

[0075] For easier understanding, see Figure 1 , the present application provides an embodiment of a variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage. The control method is applied in a variable frequency transformer fault ride-through circuit, and the circuit includes: a first grid, a second grid, a three-phase transformer, a three-phase converter, a variable frequency transformer, an H-bridge converter, a DC capacitor and a control circuit.

[0076] One end of the AC output terminal of the three-phase transformer is connected to the first power grid, and the other end is connected to the stator winding of the variable frequency transformer;

[0077] The rotor winding of the variable frequency transformer is connected to the second power grid;

[0078] The AC input terminal of the three-phase transformer is connected to the AC terminal of the three-phase converter;

[0079] The DC end of the three-phase converter is connected to the DC input end and the DC capacitor of the H-bridge converter; the DC output end of the H-bridge converter is connected to the DC motor of the variable frequency transformer;

[0080] The control circuit is connected to the control signal input terminals of the three-phase converter and the H-bridge converter respectively.

[0081] It should be noted that Figure 1 The variable frequency transformer 5 includes a stator winding 51, a rotor winding 52 and a DC motor 53; the first grid 1 is connected to one end of the AC output terminal of the three-phase transformer 3. It can be found that Figure 1 The proposed variable frequency transformer fault ride-through circuit only requires a three-phase converter 4 to be connected in series to achieve fault ride-through. Compared with the existing technology, the circuit design is simpler and clearer, which can reduce circuit complexity and circuit design costs, and can also avoid complex operations caused by complex circuits. In addition, the control circuit 8 is respectively connected to the control signal input terminals of the three-phase converter 4 and the H-bridge converter 6.

[0082] See also Figure 2, control methods include:

[0083] Step 101: Collect grid voltage, stator winding parameters, three-phase converter parameters, capacitor voltage, and rotor phase angle. The grid voltage includes the voltage of the first grid and the second grid. The stator winding parameters and three-phase converter parameters both include voltage and current.

[0084] According to the variable frequency transformer fault ride-through circuit provided above, the voltages of the first grid 1 and the second grid 2 can be collected, that is, the grid voltages can be expressed as 、 ; The stator winding parameters specifically include the stator winding voltage and stator winding current ; The three-phase converter parameters specifically include the three-phase converter voltage and the three-phase converter current ; The capacitor voltage is the voltage of the DC capacitor 7, expressed as ; The rotor phase angle is expressed as .

[0085] Step 102: Analyze and process the grid voltage, stator winding parameters, three-phase converter parameters, and rotor phase angle to obtain stator winding reactive power, three-phase converter positive-sequence current DC component, stator winding negative-sequence DC component, and multiple stator winding odd harmonic DC components.

[0086] Furthermore, step 102 includes:

[0087] Perform power calculation based on stator winding parameters to obtain stator winding reactive power;

[0088] The grid voltage and the voltage parameters of the three-phase converter parameters are subjected to phase-locked loop processing respectively to obtain the grid voltage phase angle and the three-phase converter voltage phase angle;

[0089] Performing three-phase stationary to two-phase rotating coordinate transformation on the current parameters of the three-phase converter parameters according to the voltage phase angle of the three-phase converter to obtain the DC component of the positive sequence current of the three-phase converter;

[0090] According to the grid voltage phase angle and the rotor phase angle, the stator winding parameters are transformed from three-phase static to two-phase rotating coordinates and filtered by a notch filter to obtain the stator winding negative sequence DC component and multiple stator winding odd harmonic DC components.

[0091] Furthermore, the stator winding parameters are transformed from three-phase static to two-phase rotating coordinates and filtered by a notch filter according to the grid voltage phase angle and the rotor phase angle to obtain the stator winding negative sequence DC component and multiple stator winding odd harmonic DC components, including:

[0092] Performing three-phase stationary to two-phase rotating coordinate transformation and notch filter filtering of a first preset frequency on voltage parameters of the stator winding parameters according to the grid voltage phase angle, to obtain a stator winding negative sequence voltage DC component and two stator winding odd harmonic voltage DC components;

[0093] According to the grid voltage phase angle, the current parameters of the stator winding parameters are transformed from three-phase static to two-phase rotating coordinates and filtered by a notch filter of a second preset frequency to obtain the stator winding negative sequence current DC component and two stator winding odd harmonic current DC components.

[0094] It should be noted that according to the stator winding voltage and stator winding current The power calculation can be performed directly to obtain the reactive power of the stator winding, that is, the stator winding reactive power . And the first grid voltage , the second grid voltage and the three-phase converter voltage Through phase-locked loop processing, the first grid voltage phase angle can be obtained , the second grid voltage phase angle and the three-phase converter voltage phase angle That is, the grid voltage phase angle includes the voltage phase angle of the first grid and the second grid. Then, according to the voltage phase angle of the three-phase converter The three-phase converter current can be By transforming the three-phase stationary to two-phase rotating coordinates, the DC component of the positive sequence current of the three-phase converter in the stator positive sequence synchronous rotating coordinate system can be obtained. .

[0095] According to the first grid voltage phase angle Stator winding voltage After the three-phase stationary to two-phase rotating coordinate transformation, the first frequency values ​​in the first preset frequency are respectively 、 、 The stator winding negative sequence voltage DC component in the stator negative sequence synchronous rotating coordinate system can be obtained by filtering with a notch filter. According to the first grid voltage phase angle Stator winding voltage After the three-phase stationary to two-phase rotating coordinate transformation, the second frequency values ​​in the first preset frequency are respectively 、 、 The fifth harmonic voltage DC component of the stator winding in the stator fifth harmonic synchronous rotating coordinate system can be obtained by filtering with a notch filter. According to the first grid voltage phase angle Stator winding voltage After the three-phase stationary to two-phase rotating coordinate transformation, the third frequency value in the first preset frequency is respectively 、 、 The stator winding seventh harmonic voltage DC component in the stator seventh harmonic synchronous rotating coordinate system can be obtained by filtering with a notch filter. .

[0096] According to the second grid voltage phase angle and rotor phase angle Stator winding current After the three-phase stationary to two-phase rotating coordinate transformation, the first frequency values ​​in the second preset frequency are respectively 、 、 The negative sequence current DC component of the stator winding in the rotor negative sequence synchronous rotating coordinate system can be obtained by filtering the notch filter. According to the second grid voltage phase angle and rotor phase angle Stator winding current After the three-phase stationary to two-phase rotating coordinate transformation, the second frequency values ​​in the second preset frequency are respectively 、 、 The fifth harmonic current DC component of the stator winding in the rotor fifth harmonic synchronous rotating coordinate system can be obtained by filtering with a notch filter. According to the second grid voltage phase angle and rotor phase angle Stator winding current After the three-phase stationary to two-phase rotating coordinate transformation, the third frequency value in the second preset frequency is respectively 、 、 The seventh harmonic current DC component of the stator winding in the rotor seventh harmonic synchronous rotating coordinate system can be obtained by filtering with a notch filter. .

[0097] Step 103: Analyze the capacitor voltage, stator winding reactive power, three-phase converter positive-sequence current DC component, stator winding negative-sequence DC component, and stator winding odd-numbered harmonic DC component based on a preset voltage control equation to obtain the three-phase converter positive- and negative-sequence voltage reference value DC components and multiple three-phase converter odd-numbered harmonic voltage reference value DC components.

[0098] The preset voltage control equation of this embodiment is:

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113]

[0114]

[0115] in, represents the Laplace operator, is the DC capacitor voltage reference value; is the stator winding reactive power reference value; and are the d-axis component and q-axis component of the DC component of the positive sequence current reference value of the three-phase converter respectively; and are the d-axis component and q-axis component of the DC component of the positive sequence current of the three-phase converter respectively; and are the d-axis component and q-axis component of the DC component of the positive sequence voltage reference value of the three-phase converter respectively; and are the d-axis component and q-axis component of the DC component of the stator winding negative sequence voltage respectively; and are respectively the d-axis component and the q-axis component of the DC component of the first negative sequence voltage reference value of the three-phase converter; and are the d-axis component and q-axis component of the stator winding fifth harmonic voltage DC component respectively; and are the d-axis component and q-axis component of the DC component of the first and fifth harmonic voltage reference values ​​of the three-phase converter respectively; and are the d-axis component and q-axis component of the DC component of the seventh harmonic voltage of the stator winding respectively; and are the d-axis component and q-axis component of the DC component of the first and seventh harmonic voltage reference values ​​of the three-phase converter respectively; and are the d-axis component and q-axis component of the DC component of the stator winding negative sequence current respectively; and are respectively the d-axis component and the q-axis component of the DC component of the second negative sequence voltage reference value of the three-phase converter; and are the d-axis component and q-axis component of the stator winding fifth harmonic current DC component respectively; and are the d-axis component and q-axis component of the DC component of the second and fifth harmonic voltage reference values ​​of the three-phase converter respectively; and are the d-axis component and q-axis component of the seventh harmonic current DC component of the stator winding respectively; and are the d-axis component and q-axis component of the DC component of the second and seventh harmonic voltage reference values ​​of the three-phase converter respectively; and are the proportional coefficient and integral coefficient of the DC capacitor voltage controller respectively; and are the proportional coefficient and integral coefficient of the stator winding reactive power controller respectively; and are the proportional coefficient and integral coefficient of the d-axis component controller of the positive sequence current of the three-phase converter respectively; and are the proportional coefficient and integral coefficient of the q-axis component controller of the positive sequence current of the three-phase converter respectively; and are the proportional coefficient and integral coefficient of the stator winding negative sequence voltage d-axis component controller respectively; and are the proportional coefficient and integral coefficient of the q-axis component controller of the stator winding negative sequence voltage respectively; and are the proportional coefficient and integral coefficient of the stator winding fifth harmonic voltage d-axis component controller respectively; and are the proportional coefficient and integral coefficient of the q-axis component controller of the fifth harmonic voltage of the stator winding respectively; and are the proportional coefficient and integral coefficient of the stator winding seventh harmonic voltage d-axis component controller respectively; and are the proportional coefficient and integral coefficient of the q-axis component controller of the seventh harmonic voltage of the stator winding respectively; and are the proportional coefficient and integral coefficient of the stator winding negative sequence current d-axis component controller respectively; and are the proportional coefficient and integral coefficient of the q-axis component controller of the stator winding negative sequence current respectively; and are the proportional coefficient and integral coefficient of the stator winding fifth harmonic current d-axis component controller respectively; and are the proportional coefficient and integral coefficient of the q-axis component controller of the fifth harmonic current of the stator winding respectively; and are the proportional coefficient and integral coefficient of the stator winding seventh harmonic current d-axis component controller respectively; and They are the proportional coefficient and integral coefficient of the q-axis component controller of the seventh harmonic current of the stator winding.

[0116] According to the preset voltage control equation, the capacitor voltage can be , stator winding reactive power , DC component of positive sequence current of three-phase converter , DC component of stator winding negative sequence voltage , stator winding fifth harmonic voltage DC component , stator winding seventh harmonic voltage DC component , DC component of stator winding negative sequence current , stator winding fifth harmonic current DC component and the seventh harmonic current DC component of the stator winding By analyzing, we can get the DC component of the positive sequence voltage reference value of the three-phase converter , the DC component of the first negative sequence voltage reference value of the three-phase converter , DC component of the first and fifth harmonic voltage reference values ​​of the three-phase converter , DC component of the first and seventh harmonic voltage reference values ​​of the three-phase converter , DC component of the second negative sequence voltage reference value of the three-phase converter , DC component of the second and fifth harmonic voltage reference values ​​of the three-phase converter , DC component of the second and seventh harmonic voltage reference values ​​of the three-phase converter .

[0117] Step 104 : Analyze the DC components of the positive and negative sequence voltage reference values ​​and the DC components of the odd harmonic voltage reference values ​​of the three-phase converter according to the grid voltage phase angle and the rotor phase angle to obtain a voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system.

[0118] Furthermore, step 104 includes:

[0119] According to the grid voltage phase angle, the positive sequence component in the DC component of the positive and negative sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation process to obtain the positive sequence voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system;

[0120] Performing a two-phase rotation to a two-phase stationary coordinate transformation on the first negative sequence component of the DC component of the positive and negative sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a first negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0121] According to the grid voltage phase angle, the DC component of the odd harmonic voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation process to obtain the first harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0122] Performing a two-phase rotation to two-phase stationary coordinate transformation on the second negative sequence component of the DC component of the positive and negative sequence voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, thereby obtaining a second negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0123] According to the grid voltage phase angle and the rotor phase angle, the DC component of the odd harmonic voltage reference value of the three-phase converter is transformed from a two-phase rotation to a two-phase stationary coordinate system to obtain the second harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0124] The three-phase converter voltage vector reference value in a two-phase stationary coordinate system is obtained by summing the positive-sequence voltage vector reference value of the three-phase converter, the first negative-sequence voltage vector reference value of the three-phase converter, the first harmonic voltage vector reference value of the three-phase converter, the second negative-sequence voltage vector reference value of the three-phase converter, and the second harmonic voltage vector reference value of the three-phase converter.

[0125] It should be noted that, according to the first grid voltage phase angle The DC component of the positive sequence voltage reference value of the three-phase converter can be Perform two-phase rotation to two-phase stationary coordinate transformation to obtain the positive sequence voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system According to the first grid voltage phase angle The DC component of the first negative sequence voltage reference value of the three-phase converter can also be Perform two-phase rotation to two-phase stationary coordinate transformation to obtain the first negative sequence voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system .

[0126] If the first grid voltage phase angle is used The DC component of the first and fifth harmonic voltage reference values ​​of the three-phase converter By performing two-phase rotating to two-phase stationary coordinate transformation, the first and fifth harmonic voltage vector reference values ​​of the three-phase converter can be obtained. If the first grid voltage phase angle is used The DC component of the first and seventh harmonic voltage reference values ​​of the three-phase converter By performing two-phase rotating to two-phase stationary coordinate transformation, the first and seventh harmonic voltage vector reference values ​​of the three-phase converter can be obtained. .

[0127] According to the second grid voltage phase angle and rotor phase angle The DC component of the second negative sequence voltage reference value of the three-phase converter can be Perform two-phase rotation to two-phase stationary coordinate transformation to obtain the second negative sequence voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system. .

[0128] If the second grid voltage phase angle is used and rotor phase angle The DC component of the second and fifth harmonic voltage reference values ​​of the three-phase converter By performing two-phase rotating to two-phase stationary coordinate transformation, the second and fifth harmonic voltage vector reference values ​​of the three-phase converter can be obtained. If the second grid voltage phase angle is used and rotor phase angle The DC component of the second and seventh harmonic voltage reference values ​​of the three-phase converter By performing two-phase rotating to two-phase stationary coordinate transformation, the second and seventh harmonic voltage vector reference values ​​of the three-phase converter can be obtained. .

[0129] The positive sequence voltage vector reference value of the three-phase converter , three-phase converter first negative sequence voltage vector reference value , three-phase converter first and fifth harmonic voltage vector reference values , three-phase converter first and seventh harmonic voltage vector reference values , the second negative sequence voltage vector reference value of the three-phase converter , the second and fifth harmonic voltage vector reference values ​​of the three-phase converter , the second and seventh harmonic voltage vector reference values ​​of the three-phase converter By summing, we can get the voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system .

[0130] Step 105 : Perform space vector modulation on the three-phase converter voltage vector reference value to generate a control signal for the three-phase converter switch, and implement variable frequency transformer fault ride-through control based on the control signal.

[0131] For the overall calculation and analysis process of the variable frequency transformer fault ride-through control in this embodiment, please refer to Figure 3 , the calculated three-phase converter voltage vector reference value The control signal of the three-phase converter switch can be obtained through space vector modulation SVPWM 、 、 ; Based on the control signal, the fault ride-through control of the variable frequency transformer can be realized.

[0132] The embodiments of the present application provide a variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage, which is applied to a variable frequency transformer fault ride-through circuit. This fault ride-through circuit only requires a series connection of a three-phase converter to simultaneously solve the DC capacitor voltage control problem and the problem of unbalanced grid voltage and harmonic distortion on both sides. Based on this circuit, a detailed and clear fault ride-through control method is designed. This method can still accurately calculate the control signal without relying on more three-phase converters. While ensuring the reliability of the variable frequency transformer ride-through control, it can also reduce circuit complexity, avoid large consumables and more complex operations, and meet actual fault ride-through control requirements. Therefore, the embodiments of the present application can solve the technical problems of the prior art that require at least two three-phase converters to achieve regulation and control of grid voltage imbalance and harmonic distortion fault ride-through, which obviously has large consumables and complex operations.

[0133] For easier understanding, see Figure 4 , the present application provides an embodiment of a variable frequency transformer fault ride-through control device for comprehensively regulating grid voltage, the control device being applied in a variable frequency transformer fault ride-through circuit, the circuit comprising: a first grid, a second grid, a three-phase transformer, a three-phase converter, a variable frequency transformer, an H-bridge converter, a DC capacitor, and a control circuit;

[0134] One end of the AC output terminal of the three-phase transformer is connected to the first power grid, and the other end is connected to the stator winding of the variable frequency transformer;

[0135] The rotor winding of the variable frequency transformer is connected to the second power grid;

[0136] The AC input terminal of the three-phase transformer is connected to the AC terminal of the three-phase converter;

[0137] The DC terminal of the three-phase converter is connected to the DC input terminal of the H-bridge converter and the DC capacitor;

[0138] The DC output terminal of the H-bridge converter is connected to the DC motor of the variable frequency transformer;

[0139] The control circuit is connected to the control signal input terminals of the three-phase converter and the H-bridge converter respectively;

[0140] The control device includes:

[0141] A parameter acquisition unit, configured to acquire grid voltage, stator winding parameters, three-phase converter parameters, capacitor voltage, and rotor phase angle, wherein the grid voltage includes the voltage of the first grid and the second grid, and the stator winding parameters and three-phase converter parameters include voltage and current;

[0142] The first analysis unit is used to analyze and process the grid voltage, stator winding parameters, three-phase converter parameters and rotor phase angle to obtain stator winding reactive power, three-phase converter positive sequence current DC component, stator winding negative sequence DC component and multiple stator winding odd harmonic DC components;

[0143] a second analyzing unit, configured to analyze the capacitor voltage, the stator winding reactive power, the three-phase converter positive-sequence current DC component, the stator winding negative-sequence DC component, and the stator winding odd-numbered harmonic DC component based on a preset voltage control equation, and obtain the three-phase converter positive-sequence and negative-sequence voltage reference value DC components and a plurality of three-phase converter odd-numbered harmonic voltage reference value DC components;

[0144] a third analyzing unit, configured to analyze the DC components of the positive and negative sequence voltage reference values ​​and the DC components of the odd harmonic voltage reference values ​​of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0145] The modulation control unit is used to perform space vector modulation on the voltage vector reference value of the three-phase converter, generate a control signal for the three-phase converter switch, and implement fault ride-through control of the variable frequency transformer based on the control signal.

[0146] Furthermore, the first analysis unit specifically includes:

[0147] The power calculation subunit is used to perform power calculation according to the stator winding parameters to obtain the stator winding reactive power;

[0148] A phase angle calculation subunit, configured to perform phase-locked loop processing on the grid voltage and the voltage parameters of the three-phase converter parameters to obtain the grid voltage phase angle and the three-phase converter voltage phase angle;

[0149] A positive sequence analysis subunit is used to perform a three-phase static to two-phase rotating coordinate transformation on the current parameters of the three-phase converter parameters according to the voltage phase angle of the three-phase converter to obtain a DC component of the positive sequence current of the three-phase converter;

[0150] The harmonic analysis subunit is used to perform three-phase static to two-phase rotating coordinate transformation and notch filter filtering on the stator winding parameters according to the grid voltage phase angle and the rotor phase angle, so as to obtain the stator winding negative sequence DC component and multiple stator winding odd harmonic DC components.

[0151] Furthermore, the harmonic analysis subunit is specifically used to:

[0152] Performing three-phase stationary to two-phase rotating coordinate transformation and notch filter filtering of a first preset frequency on voltage parameters of the stator winding parameters according to the grid voltage phase angle, to obtain a stator winding negative sequence voltage DC component and two stator winding odd harmonic voltage DC components;

[0153] According to the grid voltage phase angle, the current parameters of the stator winding parameters are transformed from three-phase static to two-phase rotating coordinates and filtered by a notch filter of a second preset frequency to obtain the stator winding negative sequence current DC component and two stator winding odd harmonic current DC components.

[0154] Furthermore, the third analysis unit is specifically configured to:

[0155] According to the grid voltage phase angle, the positive sequence component in the DC component of the positive and negative sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation process to obtain the positive sequence voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system;

[0156] Performing a two-phase rotation to a two-phase stationary coordinate transformation on the first negative sequence component of the DC component of the positive and negative sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a first negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0157] According to the grid voltage phase angle, a two-phase rotation to two-phase stationary coordinate transformation is performed on the DC component of the odd harmonic voltage reference value of the three-phase converter to obtain a first harmonic voltage vector reference value of the three-phase converter;

[0158] Performing a two-phase rotation to two-phase stationary coordinate transformation on the second negative sequence component of the DC component of the positive and negative sequence voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, thereby obtaining a second negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0159] According to the grid voltage phase angle and the rotor phase angle, the DC component of the odd harmonic voltage reference value of the three-phase converter is transformed from two-phase rotation to two-phase stationary coordinates to obtain the second harmonic voltage vector reference value of the three-phase converter;

[0160] The three-phase converter voltage vector reference value in a two-phase stationary coordinate system is obtained by summing the positive-sequence voltage vector reference value of the three-phase converter, the first negative-sequence voltage vector reference value of the three-phase converter, the first harmonic voltage vector reference value of the three-phase converter, the second negative-sequence voltage vector reference value of the three-phase converter, and the second harmonic voltage vector reference value of the three-phase converter.

[0161] The present application also provides a variable frequency transformer fault ride-through control device for comprehensively regulating grid voltage, the device including a processor and a memory;

[0162] The memory is used to store program codes and transmit the program codes to the processor;

[0163] The processor is used to execute the variable frequency transformer fault ride-through control method for comprehensively regulating the grid voltage in the above method embodiment according to the instructions in the program code.

[0164] The present application also provides a computer-readable storage medium, which is used to store program code, and the program code is used to execute the variable frequency transformer fault ride-through control method for comprehensively regulating the grid voltage in the above method embodiment.

[0165] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, 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.

[0166] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0167] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0168] 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 computer-readable storage medium. Based on this understanding, the technical solution of the present application, 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 computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the method described in each embodiment of the present application through a computer device (which can be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (full name: Read-Only Memory, English abbreviation: ROM), random access memory (full name: Random Access Memory, English abbreviation: RAM), disk or optical disk, and other media that can store program code.

[0169] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some of the technical features therein. 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 application.

Claims

1. A variable frequency transformer fault ride-through control method for comprehensive grid voltage regulation, characterized in that: The control method is applied to a variable frequency transformer fault ride-through circuit, the circuit comprising: a first power grid, a second power grid, a three-phase transformer, a three-phase converter, a variable frequency transformer, an H-bridge converter, a DC capacitor, and a control circuit; One end of the AC output end of the three-phase transformer is connected to the first power grid, and the other end is connected to the stator winding of the variable frequency transformer; The rotor winding of the variable frequency transformer is connected to the second power grid; The AC input terminal of the three-phase transformer is connected to the AC terminal of the three-phase converter; The DC end of the three-phase converter is connected to the DC input end of the H-bridge converter and the DC capacitor; The DC output terminal of the H-bridge converter is connected to the DC motor of the variable frequency transformer; The control circuit is connected to the control signal input terminals of the three-phase converter and the H-bridge converter respectively; The control method includes: Collecting grid voltage, stator winding parameters, three-phase converter parameters, capacitor voltage, and rotor phase angle, wherein the grid voltage includes the voltage of the first grid and the second grid, and the stator winding parameters and the three-phase converter parameters both include voltage and current; Analyzing and processing the grid voltage, the stator winding parameters, the three-phase converter parameters, and the rotor phase angle to obtain stator winding reactive power, a three-phase converter positive-sequence current DC component, a stator winding negative-sequence DC component, and a plurality of stator winding odd harmonic DC components; Analyzing the capacitor voltage, the stator winding reactive power, the three-phase converter positive-sequence current DC component, the stator winding negative-sequence DC component, and the stator winding odd-numbered harmonic DC component based on a preset voltage control equation to obtain a three-phase converter positive- and negative-sequence voltage reference value DC component and a plurality of three-phase converter odd-numbered harmonic voltage reference value DC components; Analyzing the DC components of the positive and negative sequence voltage reference values ​​and the DC components of the odd harmonic voltage reference values ​​of the three-phase converter according to the grid voltage phase angle and the rotor phase angle to obtain a voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system, including: Performing a two-phase rotation to a two-phase stationary coordinate transformation on the positive-sequence component of the DC component of the positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a positive-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; Performing a two-phase rotation to a two-phase stationary coordinate transformation on a first negative-sequence component of a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a first negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; Performing a two-phase rotation to two-phase stationary coordinate transformation on the DC component of the odd harmonic voltage reference value of the three-phase converter according to the grid voltage phase angle, to obtain a first harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; performing a two-phase rotation to two-phase stationary coordinate transformation process on a second negative-sequence component of a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a second negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; Performing a two-phase rotation to two-phase stationary coordinate transformation on the DC component of the odd harmonic voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a second harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; summing the positive-sequence voltage vector reference value of the three-phase converter, the first negative-sequence voltage vector reference value of the three-phase converter, the first harmonic voltage vector reference value of the three-phase converter, the second negative-sequence voltage vector reference value of the three-phase converter, and the second harmonic voltage vector reference value of the three-phase converter to obtain a voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; The three-phase converter voltage vector reference value is subjected to space vector modulation to generate a control signal for the three-phase converter switch, and variable frequency transformer fault ride-through control is implemented based on the control signal.

2. The method for controlling fault ride-through of a variable frequency transformer for comprehensively regulating grid voltage according to claim 1, characterized in that: The analyzing and processing of the grid voltage, the stator winding parameters, the three-phase converter parameters, and the rotor phase angle to obtain the stator winding reactive power, the three-phase converter positive sequence current DC component, the stator winding negative sequence DC component, and a plurality of stator winding odd harmonic DC components includes: Performing power calculation according to the stator winding parameters to obtain stator winding reactive power; Performing phase-locked loop processing on the grid voltage and the voltage parameters of the three-phase converter parameters to obtain a grid voltage phase angle and a three-phase converter voltage phase angle; Performing a three-phase stationary to two-phase rotating coordinate transformation on the current parameters of the three-phase converter parameters according to the voltage phase angle of the three-phase converter to obtain a DC component of the positive sequence current of the three-phase converter; The stator winding parameters are subjected to three-phase stationary to two-phase rotating coordinate transformation and notch filter filtering according to the grid voltage phase angle and the rotor phase angle to obtain a stator winding negative sequence DC component and a plurality of stator winding odd harmonic DC components.

3. The variable frequency transformer fault ride-through control method for comprehensive grid voltage regulation according to claim 2, characterized in that: The step of performing three-phase stationary to two-phase rotating coordinate transformation and notch filter filtering on the stator winding parameters according to the grid voltage phase angle and the rotor phase angle to obtain a stator winding negative sequence DC component and a plurality of stator winding odd harmonic DC components includes: Performing a three-phase stationary to two-phase rotating coordinate transformation and a notch filter filtering process of a first preset frequency on the voltage parameters of the stator winding parameters according to the grid voltage phase angle, to obtain a stator winding negative sequence voltage DC component and two stator winding odd harmonic voltage DC components; According to the grid voltage phase angle, the current parameters of the stator winding parameters are transformed from three-phase static to two-phase rotating coordinates and filtered by a notch filter of a second preset frequency to obtain a stator winding negative sequence current DC component and two stator winding odd harmonic current DC components.

4. A variable frequency transformer fault ride-through control device for comprehensive grid voltage regulation, characterized in that: The control device is applied to a variable frequency transformer fault ride-through circuit, the circuit comprising: a first power grid, a second power grid, a three-phase transformer, a three-phase converter, a variable frequency transformer, an H-bridge converter, a DC capacitor and a control circuit; One end of the AC output end of the three-phase transformer is connected to the first power grid, and the other end is connected to the stator winding of the variable frequency transformer; The rotor winding of the variable frequency transformer is connected to the second power grid; The AC input terminal of the three-phase transformer is connected to the AC terminal of the three-phase converter; The DC end of the three-phase converter is connected to the DC input end of the H-bridge converter and the DC capacitor; The DC output terminal of the H-bridge converter is connected to the DC motor of the variable frequency transformer; The control circuit is connected to the control signal input terminals of the three-phase converter and the H-bridge converter respectively; The control device comprises: a parameter acquisition unit, configured to acquire grid voltage, stator winding parameters, three-phase converter parameters, capacitor voltage, and rotor phase angle, wherein the grid voltage includes the voltage of the first grid and the second grid, and the stator winding parameters and the three-phase converter parameters both include voltage and current; a first analyzing unit, configured to analyze and process the grid voltage, the stator winding parameters, the three-phase converter parameters, and the rotor phase angle to obtain stator winding reactive power, a three-phase converter positive-sequence current DC component, a stator winding negative-sequence DC component, and a plurality of stator winding odd harmonic DC components; a second analyzing unit, configured to analyze the capacitor voltage, the stator winding reactive power, the positive-sequence DC component of the three-phase converter current, the negative-sequence DC component of the stator winding, and the odd-numbered harmonic DC component of the stator winding based on a preset voltage control equation, to obtain a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter and a plurality of DC components of an odd-numbered harmonic voltage reference value of the three-phase converter; A third analysis unit is configured to analyze the DC components of the positive and negative sequence voltage reference values ​​and the DC components of the odd harmonic voltage reference values ​​of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system. The third analysis unit is specifically configured to: Performing a two-phase rotation to a two-phase stationary coordinate transformation on the positive-sequence component of the DC component of the positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a positive-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; Performing a two-phase rotation to a two-phase stationary coordinate transformation on a first negative-sequence component of a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle, thereby obtaining a first negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; Performing a two-phase rotation to two-phase stationary coordinate transformation on the DC component of the odd harmonic voltage reference value of the three-phase converter according to the grid voltage phase angle, to obtain a first harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; performing a two-phase rotation to two-phase stationary coordinate transformation process on a second negative-sequence component of a DC component of a positive- and negative-sequence voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a second negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; Performing a two-phase rotation to two-phase stationary coordinate transformation on the DC component of the odd harmonic voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, to obtain a second harmonic voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; summing the positive-sequence voltage vector reference value of the three-phase converter, the first negative-sequence voltage vector reference value of the three-phase converter, the first harmonic voltage vector reference value of the three-phase converter, the second negative-sequence voltage vector reference value of the three-phase converter, and the second harmonic voltage vector reference value of the three-phase converter to obtain a voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; A modulation control unit is used to perform space vector modulation on the three-phase converter voltage vector reference value to generate a control signal for the three-phase converter switch, and implement variable frequency transformer fault ride-through control based on the control signal.

5. The variable frequency transformer fault ride-through control device for comprehensive grid voltage regulation according to claim 4, characterized in that: The first analysis unit specifically includes: A power calculation subunit, configured to perform power calculation based on the stator winding parameters to obtain the stator winding reactive power; a phase angle calculation subunit, configured to perform phase-locked loop processing on the grid voltage and the voltage parameters of the three-phase converter parameters, respectively, to obtain a grid voltage phase angle and a three-phase converter voltage phase angle; A positive sequence analysis subunit, configured to perform a three-phase stationary to two-phase rotating coordinate transformation on the current parameters of the three-phase converter parameters according to the voltage phase angle of the three-phase converter, to obtain a DC component of the positive sequence current of the three-phase converter; The harmonic analysis subunit is used to perform three-phase static to two-phase rotating coordinate transformation and notch filter filtering on the stator winding parameters according to the grid voltage phase angle and the rotor phase angle, so as to obtain the stator winding negative sequence DC component and multiple stator winding odd harmonic DC components.

6. The variable frequency transformer fault ride-through control device for comprehensive grid voltage regulation according to claim 5, characterized in that: The harmonic analysis subunit is specifically used for: Performing a three-phase stationary to two-phase rotating coordinate transformation and a notch filter filtering process of a first preset frequency on the voltage parameters of the stator winding parameters according to the grid voltage phase angle, to obtain a stator winding negative sequence voltage DC component and two stator winding odd harmonic voltage DC components; According to the grid voltage phase angle, the current parameters of the stator winding parameters are transformed from three-phase static to two-phase rotating coordinates and filtered by a notch filter of a second preset frequency to obtain a stator winding negative sequence current DC component and two stator winding odd harmonic current DC components.

7. A variable frequency transformer fault ride-through control device for comprehensive grid voltage regulation, characterized in that: The device includes a processor and a memory; The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage according to any one of claims 1 to 3 according to the instructions in the program code.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium is used to store program code, and the program code is used to execute the variable frequency transformer fault ride-through control method for comprehensively regulating grid voltage according to any one of claims 1 to 3.

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