Variable frequency transformer fault ride-through control method for adjusting voltage balance and related device

Abstract

The invention discloses a variable frequency transformer fault ride-through control method for adjusting voltage balance and a related device, and the method is applied to a fault ride-through circuit, and collects a power grid voltage, a stator winding parameter, a three-phase converter parameter, a capacitor voltage and a rotor phase angle; calculating a stator winding parameter and a three-phase converter positive sequence current direct-current component based on the acquired parameters; performing direct-current component calculation according to the parameters by adopting a preset voltage control equation to obtain positive-sequence and negative-sequence voltage reference value direct-current components of the three-phase converter; performing coordinate transformation on the obtained direct-current component according to a power grid voltage phase angle and a rotor phase angle to obtain a three-phase converter voltage vector reference value under a two-phase static coordinate system; and performing space vector modulation on the reference value to generate a control signal, and realizing variable frequency transformer fault ride-through control based on the control signal. The technical problems that in the prior art, at least two three-phase converters are needed to achieve power grid voltage unbalance adjustment and control, material consumption is large, and operation is complex are solved.

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 for adjusting voltage balance and a related device. Background Art

[0002] The power grid is an important framework of the energy Internet, and the interconnection of power grids will be an inevitable trend in the future development of power grids. The variable frequency transformer is a new type of power grid interconnection equipment. When the grid voltage on both sides of the variable frequency transformer is unbalanced, the current flowing through the variable frequency transformer will be unbalanced, which will cause the torque and power of the variable frequency transformer to fluctuate by twice the rotor rotation electrical angular velocity, twice the stator synchronous angular velocity, and twice the rotor synchronous angular velocity. The fluctuation of torque will reduce the mechanical life of the shaft, and the fluctuation of power will reduce the power quality of the power system.

[0003] Existing technologies usually require at least two three-phase converters to stabilize the DC capacitor voltage and solve the problem of unbalanced voltage on both sides of the power grid. From the perspective of consumable costs, this will undoubtedly consume more materials and be more expensive. From the perspective of the operating 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 adjusting voltage balance, which are used to solve the technical problems that the prior art requires at least two three-phase converters to achieve grid voltage imbalance regulation and control, and has obvious technical problems of large material consumption and complex operation.

[0005] In view of this, the first aspect of the present application provides a variable frequency transformer fault ride-through control method for adjusting voltage balance, the control method is applied in 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;

[0006] 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;

[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 end 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 comprises:

[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] Analyze and process 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 and the stator winding negative sequence DC component, wherein the stator winding negative sequence DC component includes a voltage DC component and a current DC component;

[0015] The capacitor voltage, the stator winding reactive power, the three-phase converter positive sequence current DC component and the stator winding negative sequence DC component are analyzed and processed by using a preset voltage control equation to obtain a three-phase converter positive sequence voltage reference value DC component and a three-phase converter negative sequence voltage reference value DC component, wherein the three-phase converter negative sequence voltage reference value DC component includes a first negative sequence component and a second negative sequence component;

[0016] Analyzing and processing the DC component of the positive-sequence voltage reference value of the three-phase converter and the DC component of the 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 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 grid voltage, the stator winding parameters, the three-phase converter parameters and the rotor phase angle are analyzed and processed to obtain the stator winding reactive power, the three-phase converter positive sequence current DC component and the stator winding negative sequence DC component, wherein the stator winding negative sequence DC component includes a voltage DC component and a current DC component, including:

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

[0020] According to the grid voltage, the stator winding parameters, the three-phase converter parameters and the rotor phase angle, three-phase stationary to two-phase stationary coordinate transformation, positive and negative sequence separation calculation, phase angle calculation and two-phase stationary to two-phase rotating coordinate transformation are respectively performed to obtain the positive sequence current DC component of the three-phase converter and the negative sequence DC component of the stator winding.

[0021] Preferably, the three-phase stationary to two-phase stationary coordinate transformation, positive and negative sequence separation calculation, phase angle calculation and two-phase stationary to two-phase rotating coordinate transformation are performed according to the grid voltage, the stator winding parameters, the three-phase converter parameters and the rotor phase angle to obtain the positive sequence current DC component of the three-phase converter and the negative sequence DC component of the stator winding, including:

[0022] Perform three-phase stationary to two-phase stationary coordinate transformation according to the grid voltage, the stator winding parameters and the three-phase converter parameters, respectively, to obtain a grid voltage vector, a stator winding vector and a three-phase converter vector, wherein the three-phase converter vector includes a three-phase converter voltage vector and a three-phase converter current vector;

[0023] Performing positive and negative sequence separation calculations on the grid voltage vector, the stator winding vector and the three-phase converter vector respectively, to obtain a grid positive and negative sequence voltage vector, a stator winding negative sequence vector and a three-phase converter positive sequence vector, wherein the three-phase converter positive sequence vector includes a voltage positive sequence vector and a current positive sequence vector;

[0024] Respectively calculating the phase angles of the positive and negative sequence voltage vectors of the power grid and the positive sequence vector of the three-phase converter to obtain the phase angle of the power grid voltage and the positive sequence voltage phase angle of the three-phase converter;

[0025] According to the grid voltage phase angle, the positive-sequence voltage phase angle of the three-phase converter and the rotor phase angle, the current positive-sequence vector of the three-phase converter positive-sequence vector and the stator winding negative-sequence vector are respectively transformed from two-phase static to two-phase rotating coordinates to obtain the three-phase converter positive-sequence current DC component and the stator winding negative-sequence DC component.

[0026] Preferably, the analyzing and processing of the DC component of the positive-sequence voltage reference value of the three-phase converter and the DC component of the negative-sequence voltage reference value 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] According to the grid voltage phase angle, the DC component of the positive sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a positive sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0028] According to the grid voltage phase angle, a first negative-sequence component of the DC component of the negative-sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a first negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0029] According to the grid voltage phase angle and the rotor phase angle, a second negative sequence component of the DC component of the negative sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to two-phase stationary coordinate transformation to obtain a second negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0030] 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 and the second negative-sequence voltage vector reference value of the three-phase converter are summed up to obtain the voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system.

[0031] A second aspect of the present application provides a variable frequency transformer fault ride-through control device for adjusting voltage balance, the control device being applied in 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;

[0032] 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;

[0033] The rotor winding of the variable frequency transformer is connected to the second power grid;

[0034] The AC input terminal of the three-phase transformer is connected to the AC terminal of the three-phase converter;

[0035] The DC end of the three-phase converter is connected to the DC input end of the H-bridge converter and the DC capacitor;

[0036] The DC output end of the H-bridge converter is connected to the DC motor of the variable frequency transformer;

[0037] The control circuit is connected to the control signal input terminals of the three-phase converter and the H-bridge converter respectively;

[0038] The control device comprises:

[0039] A parameter acquisition unit, used 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 include voltage and current;

[0040] A first analysis unit is used to analyze and process 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 and the stator winding negative sequence DC component, wherein the stator winding negative sequence DC component includes a voltage DC component and a current DC component;

[0041] A second analysis unit is used to analyze and process the capacitor voltage, the stator winding reactive power, the three-phase converter positive sequence current DC component and the stator winding negative sequence DC component by using a preset voltage control equation to obtain a three-phase converter positive sequence voltage reference value DC component and a three-phase converter negative sequence voltage reference value DC component, wherein the three-phase converter negative sequence voltage reference value DC component includes a first negative sequence component and a second negative sequence component;

[0042] a third analysis unit, configured to analyze and process the DC component of the positive sequence voltage reference value of the three-phase converter and the DC component of the negative sequence voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, so as to obtain a voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0043] A modulation control unit is used to perform space vector modulation on the voltage vector reference value of the three-phase converter to generate a control signal for the switch of the three-phase converter, and implement fault ride-through control of the variable frequency transformer based on the control signal.

[0044] Preferably, the first analysis unit specifically includes:

[0045] A power calculation subunit, used to perform power calculation according to the stator winding parameters to obtain the stator winding reactive power;

[0046] The coordinate transformation subunit is used to perform three-phase static to two-phase static coordinate transformation, positive and negative sequence separation calculation, phase angle calculation and two-phase static to two-phase rotating coordinate transformation according to the grid voltage, the stator winding parameters, the three-phase converter parameters and the rotor phase angle, so as to obtain the positive sequence current DC component of the three-phase converter and the negative sequence DC component of the stator winding.

[0047] Preferably, the coordinate transformation subunit is specifically used for:

[0048] Perform three-phase stationary to two-phase stationary coordinate transformation according to the grid voltage, the stator winding parameters and the three-phase converter parameters, respectively, to obtain a grid voltage vector, a stator winding vector and a three-phase converter vector, wherein the three-phase converter vector includes a three-phase converter voltage vector and a three-phase converter current vector;

[0049] Performing positive and negative sequence separation calculations on the grid voltage vector, the stator winding vector and the three-phase converter vector respectively, to obtain a grid positive and negative sequence voltage vector, a stator winding negative sequence vector and a three-phase converter positive sequence vector, wherein the three-phase converter positive sequence vector includes a voltage positive sequence vector and a current positive sequence vector;

[0050] Respectively calculating the phase angles of the positive and negative sequence voltage vectors of the power grid and the positive sequence vector of the three-phase converter to obtain the phase angle of the power grid voltage and the positive sequence voltage phase angle of the three-phase converter;

[0051] According to the grid voltage phase angle, the positive-sequence voltage phase angle of the three-phase converter and the rotor phase angle, the current positive-sequence vector of the three-phase converter positive-sequence vector and the stator winding negative-sequence vector are respectively transformed from two-phase static to two-phase rotating coordinates to obtain the three-phase converter positive-sequence current DC component and the stator winding negative-sequence DC component.

[0052] Preferably, the third analysis unit is specifically used for:

[0053] According to the grid voltage phase angle, the DC component of the positive sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a positive sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0054] According to the grid voltage phase angle, a first negative-sequence component of the DC component of the negative-sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a first negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0055] According to the grid voltage phase angle and the rotor phase angle, a second negative sequence component of the DC component of the negative sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to two-phase stationary coordinate transformation to obtain a second negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0056] 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 and the second negative-sequence voltage vector reference value of the three-phase converter are summed up to obtain the voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system.

[0057] A third aspect provides a variable frequency transformer fault ride-through control device for adjusting voltage balance, the device comprising a processor and a memory;

[0058] The memory is used to store program code and transmit the program code to the processor;

[0059] The processor is used to execute the variable frequency transformer fault ride-through control method for adjusting voltage balance described in the first aspect according to the instructions in the program code.

[0060] A fourth aspect 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 fault ride-through control method for adjusting voltage balance described in the first aspect.

[0061] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:

[0062] In the present application, a variable frequency transformer fault ride-through control method for adjusting voltage balance is provided, and the method is applied in a variable frequency transformer fault ride-through circuit, and the circuit includes: 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 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.

[0063] The control method includes: collecting 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, and the stator winding parameters and the three-phase converter parameters include voltage and current; analyzing and processing 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, stator winding negative sequence DC component includes voltage DC component and current DC component; using a preset voltage control equation to calculate the capacitor voltage, stator winding reactive power, three-phase converter positive sequence current DC component and stator winding negative sequence DC component. The negative-sequence DC component is analyzed and processed to obtain a DC component of a positive-sequence voltage reference value of the three-phase converter and a DC component of a negative-sequence voltage reference value of the three-phase converter, wherein the DC component of the negative-sequence voltage reference value of the three-phase converter includes a first negative-sequence component and a second negative-sequence component; the DC component of the positive-sequence voltage reference value of the three-phase converter and the DC component of the negative-sequence voltage reference value of the three-phase converter are analyzed and processed according to a grid voltage phase angle and a rotor phase angle to obtain a 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 of a switch of the three-phase converter, and fault ride-through control of the variable frequency transformer is realized based on the control signal.

[0064] The variable frequency transformer fault ride-through control method for adjusting voltage balance provided by the present application is applied to the variable frequency transformer fault ride-through circuit. The fault ride-through circuit only needs to connect a three-phase converter in series to solve the DC capacitor voltage control problem and the problem of voltage imbalance on both sides of the power grid at the same time. Based on this circuit, a detailed and clear fault ride-through control method is designed. The control signal can still be accurately calculated without relying on more three-phase converters. While ensuring the reliability of the variable frequency transformer ride-through control, the circuit complexity can be reduced, large consumables and more complicated operations can be avoided, and the actual fault ride-through control requirements can be met. Therefore, the present application can achieve the prior art that requires at least two three-phase converters to achieve the regulation and control of the unbalanced power grid voltage, and there are obvious technical problems of large consumables and complex operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 A schematic diagram of a variable frequency transformer fault ride-through circuit applied to a variable frequency transformer fault ride-through control method for adjusting voltage balance provided in an embodiment of the present application;

[0066] Figure 2 A flow chart of a variable frequency transformer fault ride-through control method for adjusting voltage balance provided in an embodiment of the present application;

[0067] Figure 3 A schematic diagram of the overall calculation and analysis process of the variable frequency transformer fault ride-through control method for adjusting voltage balance provided in an embodiment of the present application;

[0068] Figure 4 A schematic structural diagram of a variable frequency transformer fault ride-through control device for adjusting voltage balance provided in an embodiment of the present application. DETAILED DESCRIPTION

[0069] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0070] For easier understanding, see Figure 1 , an embodiment of a variable frequency transformer fault ride-through control method for adjusting voltage balance provided in the present application includes: the method is applied in a variable frequency transformer fault ride-through circuit, the circuit includes: 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.

[0071] 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;

[0072] The rotor winding of the variable frequency transformer is connected to the second power grid;

[0073] The AC input terminal of the three-phase transformer is connected to the AC terminal of the three-phase converter;

[0074] The DC end of the three-phase converter is connected to the DC input end of the H-bridge converter and the DC capacitor;

[0075] The DC output end of the H-bridge converter is connected to the DC motor of the variable frequency transformer;

[0076] The control circuit is connected to the control signal input terminals of the three-phase converter and the H-bridge converter respectively.

[0077] 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 power grid (1) is connected to one end of the AC output end 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 prior art, the circuit design is simpler and clearer, which can reduce circuit complexity, reduce circuit design costs, and avoid complex operations caused by complex circuits.

[0078] See also Figure 2 , control methods include:

[0079] 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 the three-phase converter parameters include voltage and current.

[0080] It should be noted that, according to the variable frequency transformer fault ride-through circuit provided above, the voltages of the first power grid (1) and the second power grid (2) can be collected, that is, the power 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 .

[0081] 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 and stator winding negative sequence DC component, wherein the stator winding negative sequence DC component includes a voltage DC component and a current DC component.

[0082] Furthermore, step 102 includes:

[0083] Power calculation is performed according to the stator winding parameters to obtain the stator winding reactive power;

[0084] According to the grid voltage, stator winding parameters, three-phase converter parameters and rotor phase angle, three-phase stationary to two-phase stationary coordinate transformation, positive and negative sequence separation calculation, phase angle calculation and two-phase stationary to two-phase rotating coordinate transformation are performed respectively to obtain the positive sequence current DC component of the three-phase converter and the negative sequence DC component of the stator winding.

[0085] Further, according to the grid voltage, stator winding parameters, three-phase converter parameters and rotor phase angle, three-phase stationary to two-phase stationary coordinate transformation, positive and negative sequence separation calculation, phase angle calculation and two-phase stationary to two-phase rotating coordinate transformation are respectively performed to obtain the positive sequence current DC component of the three-phase converter and the negative sequence DC component of the stator winding, including:

[0086] According to the grid voltage, stator winding parameters and three-phase converter parameters, three-phase stationary to two-phase stationary coordinate transformation is performed to obtain a grid voltage vector, a stator winding vector and a three-phase converter vector, wherein the three-phase converter vector includes a three-phase converter voltage vector and a three-phase converter current vector;

[0087] The positive and negative sequence separation calculations are performed on the grid voltage vector, the stator winding vector and the three-phase converter vector respectively, so as to obtain the grid positive and negative sequence voltage vector, the stator winding negative sequence vector and the three-phase converter positive sequence vector, wherein the three-phase converter positive sequence vector includes the voltage positive sequence vector and the current positive sequence vector;

[0088] The phase angles of the positive and negative sequence voltage vectors of the power grid and the positive sequence vector of the three-phase converter are calculated respectively to obtain the phase angle of the power grid voltage and the positive sequence voltage phase angle of the three-phase converter;

[0089] According to the grid voltage phase angle, the positive-sequence voltage phase angle of the three-phase converter and the rotor phase angle, the current positive-sequence vector of the three-phase converter and the negative-sequence vector of the stator winding are transformed from two-phase static to two-phase rotating coordinates to obtain the positive-sequence current DC component of the three-phase converter and the negative-sequence DC component of the stator winding.

[0090] 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 reactive power of the stator winding . The first grid voltage , the second grid voltage , stator winding voltage , stator winding current , three-phase converter voltage and the three-phase converter current By performing three-phase stationary to two-phase stationary coordinate transformation respectively, the grid voltage vector, stator winding vector, and three-phase converter vector in the two-phase stationary coordinate system can be obtained. Among them, the grid voltage vector includes the first grid voltage vector and the second grid voltage vector ; The stator winding vector includes the stator winding voltage vector and the stator winding current vector ; The three-phase converter vector includes the three-phase converter voltage vector and the three-phase converter current vector .

[0091] The first grid voltage vector , the second grid voltage vector , stator winding voltage vector , stator winding current vector , three-phase converter voltage vector and the three-phase converter current vector The positive and negative sequence separation calculations are performed respectively to obtain the positive and negative sequence voltage vectors of the power grid, the negative sequence vectors of the stator winding and the positive sequence vectors of the three-phase converter in the two-phase stationary coordinate system. Among them, the positive and negative sequence voltage vectors of the power grid include the first positive sequence voltage vector 、The first grid negative sequence voltage vector and the second grid negative sequence voltage vector ; The stator winding negative sequence vector includes the stator winding negative sequence voltage vector and the stator winding negative sequence current vector ; The positive sequence vector of the three-phase converter includes the positive sequence voltage vector of the three-phase converter and the positive sequence current vector of the three-phase converter .

[0092] According to the first grid positive sequence voltage vector 、The first grid negative sequence voltage vector 、The second grid negative sequence voltage vector and the positive sequence voltage vector of the three-phase converter The phase angles are calculated respectively to obtain the grid voltage phase angle and the positive sequence voltage phase angle of the three-phase converter. The grid voltage phase angle includes the first grid positive sequence voltage phase angle , the first grid negative sequence voltage phase angle , the second grid negative sequence voltage phase angle ; The positive sequence voltage phase angle of the three-phase converter is expressed as .

[0093] According to the negative sequence voltage phase angle of the first power grid , the second grid negative sequence voltage phase angle , three-phase converter positive sequence voltage phase angle and rotor phase angle The positive sequence current vector of the three-phase converter , stator winding negative sequence voltage vector and the stator winding negative sequence current vector The coordinate transformation from two-phase static to two-phase rotating is performed respectively to obtain the positive sequence current DC component of the three-phase converter in the stator positive sequence synchronous rotating coordinate system. And the stator winding negative sequence DC component. Among them, the stator winding negative sequence DC component includes the stator winding negative sequence voltage DC component and the DC component of the stator winding negative sequence current .

[0094] Step 103, using a preset voltage control equation to analyze and process the capacitor voltage, stator winding reactive power, three-phase converter positive-sequence current DC component and stator winding negative-sequence DC component, to obtain the three-phase converter positive-sequence voltage reference value DC component and the three-phase converter negative-sequence voltage reference value DC component, the three-phase converter negative-sequence voltage reference value DC component includes a first negative-sequence component and a second negative-sequence component.

[0095] The preset voltage control equation of this embodiment is expressed as:

[0096]

[0097] in, represents the Laplace operator, is the DC capacitor voltage reference value; is the stator winding reactive power reference value; and They 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 They 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 They 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 They are the d-axis component and q-axis component of the DC component of the negative sequence voltage of the stator winding 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 They are the d-axis component and q-axis component of the DC component of the negative sequence current of the stator winding 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 proportional coefficient and integral coefficient of the DC capacitor voltage controller respectively; and They are the proportional coefficient and integral coefficient of the stator winding reactive power controller respectively; and They are the proportional coefficient and integral coefficient of the d-axis positive sequence current controller of the three-phase converter; and They are the proportional coefficient and integral coefficient of the q-axis positive sequence current controller of the three-phase converter; and They are the proportional coefficient and integral coefficient of the stator winding d-axis negative sequence voltage controller; and They are the proportional coefficient and integral coefficient of the q-axis negative sequence voltage controller of the stator winding respectively; and They are the proportional coefficient and integral coefficient of the stator winding d-axis negative sequence current controller; and They are the proportional coefficient and integral coefficient of the q-axis negative-sequence current controller of the stator winding respectively.

[0098] The DC capacitor voltage , stator winding reactive power , DC component of positive sequence current of three-phase converter and the DC component of the stator winding negative sequence voltage and the DC component of the stator winding negative sequence current By calculating and analyzing according to the preset voltage control equation, the DC component of the positive sequence voltage reference value of the three-phase converter can be obtained. And the three-phase converter negative sequence voltage reference value DC component. Among them, the three-phase converter negative sequence voltage reference value DC component can be divided into the three-phase converter first negative sequence voltage reference value DC component and the DC component of the second negative sequence voltage reference value of the three-phase converter .

[0099] Step 104: Analyze and process the DC component of the positive-sequence voltage reference value of the three-phase converter and the DC component of the 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 voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system.

[0100] Furthermore, step 104 includes:

[0101] According to the grid voltage phase angle, the DC component of the positive sequence voltage reference value of the three-phase converter is rotated by two phases to a two-phase stationary coordinate system to obtain the positive sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0102] According to the grid voltage phase angle, the first negative sequence component of the DC component of the negative sequence voltage reference value of the three-phase converter is subjected to two-phase rotation to a 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;

[0103] According to the grid voltage phase angle and the rotor phase angle, the second negative sequence component of the DC component of the negative sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a second negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0104] 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 and the second negative sequence voltage vector reference value of the three-phase converter are summed up and calculated to obtain the voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system.

[0105] It should be noted that according to the positive sequence voltage phase angle of the first power grid The DC component of the positive sequence voltage reference value of the three-phase converter can be By performing a two-phase rotating to two-phase stationary coordinate transformation, the positive sequence voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system can be obtained. .

[0106] According to the negative sequence voltage phase angle of the first power grid The DC component of the first negative sequence voltage reference value of the three-phase converter can be Perform a 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 According to the negative sequence voltage phase angle of the second power grid 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. .

[0107] The positive sequence voltage vector reference value of the three-phase converter , three-phase converter first negative sequence voltage vector reference value and the second negative sequence voltage vector reference value of the three-phase converter Perform sum calculation to obtain the voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system .

[0108] Step 105: Perform space vector modulation on the voltage vector reference value of the three-phase converter to generate a control signal for the switch of the three-phase converter, and implement variable frequency transformer fault ride-through control based on the control signal.

[0109] For the overall calculation and analysis process of the variable frequency transformer fault ride-through control of 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.

[0110] The variable frequency transformer fault ride-through control method for adjusting voltage balance provided in the embodiment of the present application is applied to the variable frequency transformer fault ride-through circuit. The fault ride-through circuit only needs to connect a three-phase converter in series to solve the DC capacitor voltage control problem and the problem of unbalanced voltage on both sides of the power grid at the same time. Based on this circuit, a detailed and clear fault ride-through control method is designed. The control signal can still be accurately calculated without relying on more three-phase converters. While ensuring the reliability of the variable frequency transformer ride-through control, the circuit complexity can be reduced, large consumables and more complex operations can be avoided, and the actual fault ride-through control requirements can be met. Therefore, the embodiment of the present application can achieve the regulation and control of the unbalanced power grid voltage in the prior art, which requires at least two three-phase converters, and has obvious technical problems of large consumables and complex operations.

[0111] For easier understanding, see Figure 4 , the present application provides an embodiment of a variable frequency transformer fault ride-through control device for adjusting voltage balance, the control device is applied in 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;

[0112] 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;

[0113] The rotor winding of the variable frequency transformer is connected to the second power grid;

[0114] The AC input terminal of the three-phase transformer is connected to the AC terminal of the three-phase converter;

[0115] The DC end of the three-phase converter is connected to the DC input end of the H-bridge converter and the DC capacitor;

[0116] The DC output end of the H-bridge converter is connected to the DC motor of the variable frequency transformer;

[0117] The control circuit is connected to the control signal input terminals of the three-phase converter and the H-bridge converter respectively;

[0118] The control device includes:

[0119] The parameter acquisition unit 201 is used to acquire the 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, and the stator winding parameters and the three-phase converter parameters include voltage and current;

[0120] The first analysis unit 202 is used to analyze and process the grid voltage, stator winding parameters, three-phase converter parameters and rotor phase angle to obtain the stator winding reactive power, the three-phase converter positive sequence current DC component and the stator winding negative sequence DC component, where the stator winding negative sequence DC component includes a voltage DC component and a current DC component;

[0121] The second analysis unit 203 is used to analyze and process the capacitor voltage, the stator winding reactive power, the three-phase converter positive sequence current DC component and the stator winding negative sequence DC component by using a preset voltage control equation to obtain the three-phase converter positive sequence voltage reference value DC component and the three-phase converter negative sequence voltage reference value DC component, wherein the three-phase converter negative sequence voltage reference value DC component includes a first negative sequence component and a second negative sequence component;

[0122] The third analysis unit 204 is used to analyze and process the DC component of the positive sequence voltage reference value of the three-phase converter and the DC component of the negative sequence voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, and obtain the voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system;

[0123] The modulation control unit 205 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.

[0124] Furthermore, the first analysis unit 202 specifically includes:

[0125] The power calculation subunit 2021 is used to perform power calculation according to the stator winding parameters to obtain the stator winding reactive power;

[0126] The coordinate transformation subunit 2022 is used to perform three-phase static to two-phase static coordinate transformation, positive and negative sequence separation calculation, phase angle calculation and two-phase static to two-phase rotating coordinate transformation according to the grid voltage, stator winding parameters, three-phase converter parameters and rotor phase angle, so as to obtain the positive sequence current DC component of the three-phase converter and the negative sequence DC component of the stator winding.

[0127] Furthermore, the coordinate transformation subunit 2022 is specifically used for:

[0128] According to the grid voltage, stator winding parameters and three-phase converter parameters, three-phase stationary to two-phase stationary coordinate transformation is performed to obtain a grid voltage vector, a stator winding vector and a three-phase converter vector, wherein the three-phase converter vector includes a three-phase converter voltage vector and a three-phase converter current vector;

[0129] The positive and negative sequence separation calculations are performed on the grid voltage vector, the stator winding vector and the three-phase converter vector respectively, so as to obtain the grid positive and negative sequence voltage vector, the stator winding negative sequence vector and the three-phase converter positive sequence vector, wherein the three-phase converter positive sequence vector includes the voltage positive sequence vector and the current positive sequence vector;

[0130] The phase angles of the positive and negative sequence voltage vectors of the power grid and the positive sequence vector of the three-phase converter are calculated respectively to obtain the phase angle of the power grid voltage and the positive sequence voltage phase angle of the three-phase converter;

[0131] According to the grid voltage phase angle, the positive-sequence voltage phase angle of the three-phase converter and the rotor phase angle, the current positive-sequence vector of the three-phase converter and the negative-sequence vector of the stator winding are transformed from two-phase static to two-phase rotating coordinates to obtain the positive-sequence current DC component of the three-phase converter and the negative-sequence DC component of the stator winding.

[0132] Further, the third analysis unit 204 is specifically configured to:

[0133] According to the grid voltage phase angle, the DC component of the positive sequence voltage reference value of the three-phase converter is rotated by two phases to a two-phase stationary coordinate system to obtain the positive sequence voltage vector reference value of the three-phase converter in the two-phase stationary coordinate system;

[0134] According to the grid voltage phase angle, the first negative sequence component of the DC component of the negative sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a first negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system;

[0135] According to the grid voltage phase angle and the rotor phase angle, the second negative sequence component of the DC component of the negative sequence voltage reference value of the three-phase converter is subjected to a coordinate transformation from two-phase rotation to two-phase static, so as to obtain the second negative sequence voltage vector reference value of the three-phase converter in the two-phase static coordinate system;

[0136] 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 and the second negative sequence voltage vector reference value of the three-phase converter are summed up and calculated to obtain the voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system.

[0137] The present application also provides a variable frequency transformer fault ride-through control device for adjusting voltage balance, the device comprising a processor and a memory;

[0138] The memory is used to store the program code and transmit the program code to the processor;

[0139] The processor is used to execute the variable frequency transformer fault ride-through control method for adjusting voltage balance in the above method embodiment according to the instructions in the program code.

[0140] 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 adjusting voltage balance in the above method embodiment.

[0141] In the several embodiments provided in the present 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 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.

[0142] 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.

[0143] In addition, each functional unit in each embodiment of the present application 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.

[0144] 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 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 computer software product is stored in a storage medium, including a number of 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 in English: Read-Only Memory, English abbreviation: ROM), random access memory (full name in English: Random Access Memory, English abbreviation: RAM), disk or optical disk and other media that can store program codes.

[0145] 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned 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 adjusting voltage balance, characterized in that: The control method is applied in 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 end 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 comprises: 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; Analyze and process 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 and the stator winding negative sequence DC component, wherein the stator winding negative sequence DC component includes a voltage DC component and a current DC component; The capacitor voltage, the stator winding reactive power, the three-phase converter positive sequence current DC component and the stator winding negative sequence DC component are analyzed and processed by using a preset voltage control equation to obtain a three-phase converter positive sequence voltage reference value DC component and a three-phase converter negative sequence voltage reference value DC component, wherein the three-phase converter negative sequence voltage reference value DC component includes a first negative sequence component and a second negative sequence component; Analyzing and processing the DC component of the positive-sequence voltage reference value of the three-phase converter and the DC component of the 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 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 variable frequency transformer fault ride-through control method for adjusting voltage balance according to claim 1, characterized in that: The grid voltage, the stator winding parameters, the three-phase converter parameters and the rotor phase angle are analyzed and processed to obtain the stator winding reactive power, the three-phase converter positive sequence current DC component and the stator winding negative sequence DC component, wherein the stator winding negative sequence DC component includes a voltage DC component and a current DC component, including: Performing power calculation according to the stator winding parameters to obtain the stator winding reactive power; According to the grid voltage, the stator winding parameters, the three-phase converter parameters and the rotor phase angle, three-phase stationary to two-phase stationary coordinate transformation, positive and negative sequence separation calculation, phase angle calculation and two-phase stationary to two-phase rotating coordinate transformation are respectively performed to obtain the positive sequence current DC component of the three-phase converter and the negative sequence DC component of the stator winding.

3. The variable frequency transformer fault ride-through control method for adjusting voltage balance according to claim 2, characterized in that: The method of performing three-phase stationary to two-phase stationary coordinate transformation, positive and negative sequence separation calculation, phase angle calculation and two-phase stationary to two-phase rotating coordinate transformation processing according to the grid voltage, the stator winding parameters, the three-phase converter parameters and the rotor phase angle to obtain the positive sequence current DC component of the three-phase converter and the negative sequence DC component of the stator winding includes: Perform three-phase stationary to two-phase stationary coordinate transformation according to the grid voltage, the stator winding parameters and the three-phase converter parameters, respectively, to obtain a grid voltage vector, a stator winding vector and a three-phase converter vector, wherein the three-phase converter vector includes a three-phase converter voltage vector and a three-phase converter current vector; Performing positive and negative sequence separation calculations on the grid voltage vector, the stator winding vector and the three-phase converter vector respectively, to obtain a grid positive and negative sequence voltage vector, a stator winding negative sequence vector and a three-phase converter positive sequence vector, wherein the three-phase converter positive sequence vector includes a voltage positive sequence vector and a current positive sequence vector; Respectively calculating the phase angles of the positive and negative sequence voltage vectors of the power grid and the positive sequence vector of the three-phase converter to obtain the phase angle of the power grid voltage and the positive sequence voltage phase angle of the three-phase converter; According to the grid voltage phase angle, the positive-sequence voltage phase angle of the three-phase converter and the rotor phase angle, the current positive-sequence vector of the three-phase converter positive-sequence vector and the stator winding negative-sequence vector are respectively transformed from two-phase static to two-phase rotating coordinates to obtain the three-phase converter positive-sequence current DC component and the stator winding negative-sequence DC component.

4. The variable frequency transformer fault ride-through control method for adjusting voltage balance according to claim 1, characterized in that: The analyzing and processing the DC component of the positive sequence voltage reference value of the three-phase converter and the DC component of the negative sequence voltage reference value 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: According to the grid voltage phase angle, the DC component of the positive sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a positive sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; According to the grid voltage phase angle, a first negative-sequence component of the DC component of the negative-sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a first negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; According to the grid voltage phase angle and the rotor phase angle, a second negative sequence component of the DC component of the negative sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to two-phase stationary coordinate transformation to obtain a second negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; 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 and the second negative-sequence voltage vector reference value of the three-phase converter are summed up to obtain the voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system.

5. A variable frequency transformer fault ride-through control device for adjusting voltage balance, characterized in that: The control device is applied in 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 end 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, used 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 include voltage and current; A first analysis unit is used to analyze and process 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 and the stator winding negative sequence DC component, wherein the stator winding negative sequence DC component includes a voltage DC component and a current DC component; A second analysis unit is used to analyze and process the capacitor voltage, the stator winding reactive power, the three-phase converter positive sequence current DC component and the stator winding negative sequence DC component by using a preset voltage control equation to obtain a three-phase converter positive sequence voltage reference value DC component and a three-phase converter negative sequence voltage reference value DC component, wherein the three-phase converter negative sequence voltage reference value DC component includes a first negative sequence component and a second negative sequence component; a third analysis unit, configured to analyze and process the DC component of the positive sequence voltage reference value of the three-phase converter and the DC component of the negative sequence voltage reference value of the three-phase converter according to the grid voltage phase angle and the rotor phase angle, so as 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 voltage vector reference value of the three-phase converter to generate a control signal for the switch of the three-phase converter, and implement fault ride-through control of the variable frequency transformer based on the control signal.

6. The variable frequency transformer fault ride-through control device for adjusting voltage balance according to claim 5, characterized in that: The first analysis unit specifically includes: A power calculation subunit, used to perform power calculation according to the stator winding parameters to obtain the stator winding reactive power; The coordinate transformation subunit is used to perform three-phase static to two-phase static coordinate transformation, positive and negative sequence separation calculation, phase angle calculation and two-phase static to two-phase rotating coordinate transformation according to the grid voltage, the stator winding parameters, the three-phase converter parameters and the rotor phase angle, so as to obtain the positive sequence current DC component of the three-phase converter and the negative sequence DC component of the stator winding.

7. The variable frequency transformer fault ride-through control device for adjusting voltage balance according to claim 6, characterized in that: The coordinate transformation subunit is specifically used for: Perform three-phase stationary to two-phase stationary coordinate transformation according to the grid voltage, the stator winding parameters and the three-phase converter parameters, respectively, to obtain a grid voltage vector, a stator winding vector and a three-phase converter vector, wherein the three-phase converter vector includes a three-phase converter voltage vector and a three-phase converter current vector; Performing positive and negative sequence separation calculations on the grid voltage vector, the stator winding vector and the three-phase converter vector respectively, to obtain a grid positive and negative sequence voltage vector, a stator winding negative sequence vector and a three-phase converter positive sequence vector, wherein the three-phase converter positive sequence vector includes a voltage positive sequence vector and a current positive sequence vector; Respectively calculating the phase angles of the positive and negative sequence voltage vectors of the power grid and the positive sequence vector of the three-phase converter to obtain the phase angle of the power grid voltage and the positive sequence voltage phase angle of the three-phase converter; According to the grid voltage phase angle, the positive-sequence voltage phase angle of the three-phase converter and the rotor phase angle, the current positive-sequence vector of the three-phase converter positive-sequence vector and the stator winding negative-sequence vector are respectively transformed from two-phase static to two-phase rotating coordinates to obtain the three-phase converter positive-sequence current DC component and the stator winding negative-sequence DC component.

8. The variable frequency transformer fault ride-through control device for adjusting voltage balance according to claim 5, characterized in that: The third analysis unit is specifically used for: According to the grid voltage phase angle, the DC component of the positive sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a positive sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; According to the grid voltage phase angle, a first negative-sequence component of the DC component of the negative-sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to a two-phase stationary coordinate transformation to obtain a first negative-sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; According to the grid voltage phase angle and the rotor phase angle, a second negative sequence component of the DC component of the negative sequence voltage reference value of the three-phase converter is subjected to a two-phase rotation to two-phase stationary coordinate transformation to obtain a second negative sequence voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system; 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 and the second negative-sequence voltage vector reference value of the three-phase converter are summed up to obtain the voltage vector reference value of the three-phase converter in a two-phase stationary coordinate system.

9. A variable frequency transformer fault ride-through control device for adjusting voltage balance, characterized in that: The device comprises a processor and a memory; The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the variable frequency transformer fault ride-through control method for adjusting voltage balance according to the instructions in the program code as described in any one of claims 1-4.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and the program codes are used to execute the variable frequency transformer fault ride-through control method for adjusting voltage balance according to any one of claims 1 to 4.

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