Phase-split power control method for three-phase voltage source converter based on negative sequence current injection

Abstract

The present application provides a three-phase voltage source converter split-phase power control method based on negative-sequence current injection, comprising: obtaining the three-phase grid voltage and three-phase grid current in the phasor domain of the three-phase voltage source converter; obtaining the power calculation formula of the three-phase voltage source converter; determining the target relationship; and controlling the operation of the three-phase voltage source converter using a first control method or a second control method according to the target relationship, wherein the first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the second control method is a control method for independently controlling the reactive power of each phase and the total active power. This method proposes a new three-phase voltage source converter split-phase power control strategy based on negative-sequence current injection by deriving and analyzing the mathematical relationship between the single-phase power in the phase domain and the positive and negative sequence components of the current, thereby realizing independent regulation of the average power of each phase and achieving the effect of fully compensating for the three-phase imbalance of the distribution network.

Description

Technical Field

[0001] The present application relates to the field of power control of three-phase voltage source converters, and specifically to a method for controlling the split-phase power of a three-phase voltage source converter based on negative-sequence current injection, a control device for the split-phase power of a three-phase voltage source converter based on negative-sequence current injection, a computer-readable storage medium, and an electronic device. Background Art

[0002] Three-phase imbalance is currently the most common power quality issue in distribution networks. The large-scale integration of distributed power sources and the use of numerous power electronic devices are exacerbating this imbalance. This can increase line losses and reduce the lifespan of equipment, making it essential to address this issue.

[0003] There are currently three common methods for managing three-phase imbalance problems in engineering applications. One is based on a phase-change switch method, which compensates by changing the load phase connection relationship according to the instantaneous phase power or current; the other is based on a capacitor-type reactive compensation device method, which adjusts and compensates by switching capacitors and reactors; and the other is based on a power electronic device method, which compensates for the active and reactive power between phases by adjusting the output power.

[0004] The above three existing methods for solving the three-phase imbalance problem have the following disadvantages:

[0005] 1. Three-phase imbalance control based on phase change switches. This method changes the load phase connection relationship according to the instantaneous phase power or current to achieve inter-phase transfer of three-phase load power to reduce the imbalance. However, this method requires a series of manual optimization of switching behavior and does not have the reactive power compensation function.

[0006] 2. Three-phase imbalance control is performed based on a capacitive reactive power compensation device. This method adjusts and compensates the capacitors and reactors by switching on and off according to the real-time three-phase imbalance. However, since the capacity of the capacitors is grouped and graded, this method cannot achieve complete compensation.

[0007] 3. Three-phase imbalance control using power electronic device compensation devices. This method compensates for interphase active and reactive power by adjusting output power or by compensating line parameters to achieve a set balanced voltage at the common coupling point. However, this method is limited by installation location and asset management, and its full effectiveness is limited, requiring additional investment costs. Summary of the Invention

[0008] The main purpose of the present application is to provide a method for controlling the split-phase power of a three-phase voltage source converter based on negative-sequence current injection, a control device for the split-phase power of a three-phase voltage source converter based on negative-sequence current injection, a computer-readable storage medium and an electronic device, so as to at least solve the problem that the existing three-phase imbalance control method cannot meet the requirements of independent regulation of active and reactive power of all phases, cannot achieve the effect of complete compensation, and consumes a lot of human resources and is costly.

[0009] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a method for controlling the phase power of a three-phase voltage source converter based on negative-sequence current injection is provided, comprising: obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory; obtaining a power calculation formula of the three-phase voltage source converter, the power calculation formula being used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter; determining a target relationship formula according to the three-phase grid voltage, the three-phase grid current and the power calculation formula, the target relationship formula characterizing the relationship between positive-sequence voltage, negative-sequence voltage, positive-sequence current, negative-sequence current, active power of each phase and reactive power of each phase; controlling the operation of the three-phase voltage source converter using a first control method or a second control method according to the target relationship formula, the first control method being a control method for independently controlling the active power of each phase and the total reactive power, and the second control method being a control method for independently controlling the reactive power of each phase and the total active power.

[0010] Optionally, according to the target relationship, a first control method is used to control the operation of the three-phase voltage source converter, including: determining a total reactive power calculation formula Q of the three-phase voltage source converter sum =Q a +Q b +Q c , where Q sum is the total reactive power, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase C; according to the total reactive power calculation formula and the target relationship formula, a first instruction value determination calculation formula is determined, and according to the first instruction value determination calculation formula, a first target instruction value is determined, the first target instruction value includes the positive and negative sequence current dq axis component instruction value, the active power instruction value of each phase and the total reactive power instruction value; the first target instruction value is used to control the operation of the three-phase voltage source converter.

[0011] Optionally, determining the first instruction value determination calculation formula according to the total reactive power calculation formula and the target relationship formula includes: determining the first instruction value determination calculation formula [idP ref i qP ref i dN ref i qN ref ] T =T P -1 ×[P a ref P b ref P c ref Q sum ref ] T , where i dP ref 、i qP ref 、i dN ref 、i qN ref are the dq axis component command values ​​of the positive and negative sequence current respectively; P a ref 、P b ref 、P c ref are the active power command values ​​of phases a, b, and c respectively; Q sum ref are the total reactive power command values ​​respectively.

[0012] Optionally, according to the target relationship, a second control method is used to control the operation of the three-phase voltage source converter, including: determining a total active power calculation formula P of the three-phase voltage source converter sum =P a +P b +P c , where P sum is the total active power, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase C; according to the total active power calculation formula and the target relationship formula, a second instruction value determination formula is determined, and according to the second instruction value determination formula, a second target instruction value is determined, and the second target instruction value includes the reactive power instruction value and the total active power instruction value of each phase; the second target instruction value is used to control the operation of the three-phase voltage source converter.

[0013] Optionally, determining the second instruction value determination calculation formula according to the total active power calculation formula and the target relationship formula includes: determining the second instruction value determination calculation formula [i dP ref i qP ref i dN ref i qN ref ]=T Q -1 [Q a ref Q b ref Q c ref P sum ref ], where Q a ref , Q b ref , Q c ref are the reactive power command values ​​of phases a, b, and c respectively; P sum ref are the total active power command values ​​respectively.

[0014] Optionally, obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory includes: obtaining the three-phase grid voltage in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory, wherein the three-phase grid voltage is expressed as in, are the grid voltage phasors of phases a, b, and c respectively; e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; according to the symmetrical component theory, the three-phase grid current in the phasor domain of the three-phase voltage source converter is obtained, wherein the three-phase grid current is expressed as in, are the grid current phasors of phases a, b, and c, respectively, i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

[0015] Optionally, determining the target relationship according to the three-phase grid voltage, the three-phase grid current and the power calculation formula includes: determining the target relationship according to the three-phase grid voltage, the three-phase grid current and the power calculation formula Among them, Pa is the active power of phase a, P b is the active power of phase b, P c is the active power of phase c, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase c, e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

[0016] According to another aspect of the present application, a control device for the phase power of a three-phase voltage source converter based on negative-sequence current injection is provided, comprising: a first acquisition unit, configured to acquire the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory; a second acquisition unit, configured to acquire a power calculation formula of the three-phase voltage source converter, wherein the power calculation formula is used to calculate the active power and the reactive power of the three-phase voltage source converter; a determination unit, configured to determine a target relationship formula based on the three-phase grid voltage, the three-phase grid current, and the power calculation formula, wherein the target relationship formula represents the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase, and the reactive power of each phase; and a control unit, configured to control the operation of the three-phase voltage source converter using a first control method or a second control method according to the target relationship formula, wherein the first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the second control method is a control method for independently controlling the reactive power of each phase and the total active power.

[0017] According to another aspect of the present application, a computer-readable storage medium is provided, which includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute any one of the methods for controlling the phase power of a three-phase voltage source converter based on negative-sequence current injection.

[0018] According to another aspect of the present application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include methods for executing any one of the control methods for the phase-splitting power of a three-phase voltage source converter based on negative-sequence current injection.

[0019] Applying the technical solution of the present application, the above-mentioned phase-split power control method of the three-phase voltage source converter based on negative-sequence current injection first obtains the three-phase grid voltage and three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory; then obtains the power calculation formula of the three-phase voltage source converter, and the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter; then, according to the three-phase grid voltage, the three-phase grid current and the power calculation formula, the target relationship formula is determined, and the target relationship formula characterizes the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase and the reactive power of each phase; finally, according to the target relationship formula, the first control method or the second control method is adopted to control the operation of the three-phase voltage source converter, the first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the second control method is a control method for independently controlling the reactive power of each phase and the total active power. This method derives and analyzes the mathematical relationship between single-phase power in the phase domain and the positive and negative sequence components of current, and proposes a new phase-splitting power control strategy for three-phase voltage source converter based on injecting negative sequence current, which realizes independent adjustment of the average power of each phase and achieves the effect of fully compensating for the three-phase imbalance of the distribution network. It solves the problems that the existing three-phase imbalance control methods cannot meet the requirements of independent adjustment of active and reactive power of all phases, cannot achieve the effect of full compensation, and consume large human resources and high costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings that constitute part of this application are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation on this application. In the drawings:

[0021] Figure 1 A hardware structure block diagram of a mobile terminal for executing a method for controlling split-phase power of a three-phase voltage source converter based on negative sequence current injection according to an embodiment of the present application is shown;

[0022] Figure 2 A schematic flow chart of a method for controlling split-phase power of a three-phase voltage source converter based on negative sequence current injection according to an embodiment of the present application is shown;

[0023] Figure 3 A framework diagram of a three-phase voltage source converter phase-splitting power control strategy provided according to an embodiment of the present application is shown;

[0024] Figure 4 A main circuit diagram of a simulation system model provided according to an embodiment of the present application is shown;

[0025] Figure 5A simulation result diagram of an SPTQ control scheme provided according to an embodiment of the present application is shown;

[0026] Figure 6 A structural block diagram of a three-phase voltage source converter split-phase power control device based on negative sequence current injection according to an embodiment of the present application is shown.

[0027] The above drawings include the following reference numerals:

[0028] 102. Processor; 104. Memory; 106. Transmission device; 108. Input / output device. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0030] In order to enable those skilled in the art to 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 drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] As introduced in the background technology, the existing method of three-phase imbalance control based on phase change switches requires a series of manual optimization of switching behaviors and does not have the reactive power compensation function; the method of three-phase imbalance control based on capacitor-type reactive compensation devices cannot achieve complete compensation because the capacity of capacitors is grouped and graded; the method of three-phase imbalance control based on power electronic device compensation devices is restricted by installation location and asset management, cannot fully play its role, and requires additional investment costs.

[0033] In order to solve the problems that the existing three-phase imbalance control methods cannot meet the requirements of independent regulation of active and reactive power in all phases, cannot achieve the effect of complete compensation, and consume large human resources and have high costs, the embodiments of the present application provide a control method for the phase-splitting power of a three-phase voltage source converter based on negative-sequence current injection, a control device for the phase-splitting power of a three-phase voltage source converter based on negative-sequence current injection, a computer-readable storage medium and an electronic device.

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0035] The method embodiments provided in the embodiments of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking running on a mobile terminal as an example, Figure 1 This is a hardware structure block diagram of a mobile terminal for a method of controlling the phase power of a three-phase voltage source converter based on negative sequence current injection according to an embodiment of the present invention. Figure 1 As shown, the mobile terminal may include one or more ( Figure 1 Only one is shown) a processor 102 (the processor 102 may include but is not limited to a microprocessor MCU or a programmable logic device FPGA and other processing devices) and a memory 104 for storing data, wherein the mobile terminal may also include a transmission device 106 and an input and output device 108 for communication functions. It will be understood by those skilled in the art that Figure 1 The structure shown is only for illustration and does not limit the structure of the mobile terminal. Figure 1 More or fewer components than shown, or with Figure 1 Different configurations shown.

[0036] The memory 104 can be used to store computer programs, such as application software programs and modules, such as the computer program corresponding to the method for controlling the split-phase power of a three-phase voltage source converter based on negative sequence current injection in an embodiment of the present invention. The processor 102 executes the computer program stored in the memory 104 to perform various functional applications and data processing, thereby implementing the above-mentioned method. The memory 104 may include high-speed random access memory and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include a memory remotely located relative to the processor 102, and such remote memory may be connected to the mobile terminal via a network. Examples of such networks include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof. The transmission device 106 is used to receive or transmit data via a network. Specific examples of such networks may include a wireless network provided by the mobile terminal's telecommunications provider. In one example, the transmission device 106 includes a network interface controller (NIC), which can be connected to other network devices via a base station to enable communication with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0037] In this embodiment, a method for controlling the phase power of a three-phase voltage source converter based on negative sequence current injection is provided, which runs on a mobile terminal, a computer terminal or a similar computing device. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0038] Figure 2 FIG. 1 is a flow chart of a method for controlling the phase power of a three-phase voltage source converter based on negative sequence current injection according to an embodiment of the present application. Figure 2 As shown, the method includes the following steps:

[0039] Step S201, obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory;

[0040] According to the symmetrical component theory, obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter includes the following steps:

[0041] In step S2011, according to the symmetrical component theory, the three-phase grid voltage in the phasor domain of the three-phase voltage source converter is obtained, wherein the three-phase grid voltage is expressed as formula (1):

[0042]

[0043] in, are the grid voltage phasors of phases a, b, and c respectively; e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively;

[0044] In step S2012, according to the symmetrical component theory, the three-phase grid current in the phasor domain of the three-phase voltage source converter is obtained, wherein the three-phase grid current is expressed as formula (2):

[0045]

[0046] in, are the grid current phasors of phases a, b, and c, respectively, i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

[0047] Specifically, this allows accurate determination of the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter.

[0048] Step S202, obtaining a power calculation formula of the three-phase voltage source converter, wherein the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter;

[0049] Specifically, the active power and reactive power of any phase x (x = a, b, c) can be calculated in the phase domain as Equation (3):

[0050]

[0051] Where, P x , Q x are the active power and reactive power of phase x respectively; the symbol “*” on the superscript represents the conjugate of the complex number (phasor).

[0052] Step S203: determining a target relationship equation based on the three-phase grid voltage, the three-phase grid current, and the power calculation equation, wherein the target relationship equation represents the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase, and the reactive power of each phase;

[0053] Substituting the grid voltage and grid current phasor expressions in equations (1) and (2) into equation (3), the correlation between the positive and negative sequence voltage / current and each phase power can be obtained, as shown in equation (4):

[0054]

[0055] Among them, considering that the negative sequence voltage component of the three-phase voltage source converter can usually be ignored during normal operation, and due to the effect of the phase-locked loop, e qP Usually close to zero, e qP 、e dN and e qN Set to zero, and determine the target relationship according to the three-phase grid voltage, the three-phase grid current and the power calculation formula, including: determining the target relationship (5) according to the three-phase grid voltage, the three-phase grid current and the power calculation formula:

[0056]

[0057] Among them, formula (5) is simplified from formula (4), P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase c, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase c, e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

[0058] Specifically, in this way, the power of the three-phase voltage source converter can be accurately calculated according to the target relationship.

[0059] The purpose of phase power control is to adjust the active and reactive power of each phase by injecting negative sequence current. However, from formula (5), we can see that the target component has 6 phase power components P a , Q a 、P b , Q b 、P c , Q c , the controllable amount is only i dP 、i qP 、i dN 、i qN4 components, and the coefficient matrix is ​​not rank-full and irreversible. Therefore, it is impossible to achieve independent regulation of active and reactive power in all phases, and the number of control targets needs to be reduced. Therefore, to solve this problem, the first control method (split-phase active power and total reactive power control scheme, referred to as SPTQ control scheme) and the second control method (split-phase reactive power and total active power control scheme, referred to as SQTP control scheme) are proposed to control the three-phase voltage source converter.

[0060] Step S204, according to the above-mentioned target relationship, adopt the first control method or the second control method to control the operation of the above-mentioned three-phase voltage source converter, the above-mentioned first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the above-mentioned second control method is a control method for independently controlling the reactive power of each phase and the total active power.

[0061] The first control method is used to control the operation of the three-phase voltage source converter according to the target relationship, including the following steps:

[0062] Step S301, determine the total reactive power calculation formula (6) of the three-phase voltage source converter:

[0063] Q sum =Q a +Q b +Q c (6)

[0064] Among them, Q sum is the total reactive power mentioned above, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase c;

[0065] Substituting formula (6) into formula (5) yields formula (7):

[0066]

[0067] Step S302: Determine a first command value determination formula based on the total reactive power calculation formula and the target relationship formula, and determine a first target command value based on the first command value determination formula, where the first target command value includes the positive and negative sequence current dq-axis component command values, the active power command value of each phase, and the total reactive power command value.

[0068] The first instruction value determination calculation formula is determined according to the total reactive power calculation formula and the target relationship formula, including: determining the first instruction value determination calculation formula (8) according to the total reactive power calculation formula and the target relationship formula:

[0069] [i dPref i qP ref i dN ref i qN ref ] T =T P -1 ×[P a ref P b ref P c ref Q sum ref ] T (8)

[0070] Among them, the required positive and negative sequence current dq axis component command value can be obtained by reversing equation (7), i dP ref 、i qP ref 、i dN ref 、i qN ref are the dq axis component command values ​​of the positive and negative sequence current respectively; P a ref 、P b ref 、P c ref are the active power command values ​​of phases a, b, and c respectively; Q sum ref are the total reactive power command values ​​respectively.

[0071] According to formula (8), formula (9) can be obtained:

[0072]

[0073] Specifically, in this way, the first instruction value determination calculation formula can be accurately determined, thereby ensuring the subsequent accurate determination of the positive and negative sequence current dq axis component instruction values, the active power instruction value of each phase, and the total reactive power instruction value.

[0074] Step S303: Use the first target command value to control the operation of the three-phase voltage source converter.

[0075] Specifically, this can automatically perform phase compensation based on the power imbalance without the need for human intervention and optimization, and has a reactive power regulation function.

[0076] The second control method is used to control the operation of the three-phase voltage source converter according to the target relationship, including the following steps:

[0077] Step S401, determine the total active power calculation formula (10) of the three-phase voltage source converter:

[0078] P sum =P a +P b +P c (10)

[0079] Among them, P sum is the total active power mentioned above, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase c;

[0080] Step S402: Determine a second command value determination formula based on the total active power calculation formula and the target relationship formula, and determine a second target command value based on the second command value determination formula, wherein the second target command value includes a reactive power command value and a total active power command value for each phase;

[0081] The method of determining the second instruction value determination formula according to the total active power calculation formula and the target relationship formula includes: determining the second instruction value determination formula (11) according to the total active power calculation formula and the target relationship formula:

[0082] [i dP ref i qP ref i dN ref i qN ref ]=T Q -1 [Q a ref Q b ref Q c ref P sum ref ] (11)

[0083] Among them, Q a ref , Q b ref , Q c ref are the reactive power command values ​​of phases a, b, and c respectively; P sum ref are the total active power command values ​​respectively.

[0084] According to formula (11), formula (12) can be obtained:

[0085]

[0086] Specifically, in this way, the second command value determination calculation formula can be accurately determined, thereby ensuring the subsequent accurate determination of the reactive power command value and the total active power command value of each phase.

[0087] Step S403: Use the second target command value to control the operation of the three-phase voltage source converter.

[0088] Specifically, this can automatically perform phase compensation according to the power imbalance amount without the need for human intervention optimization, and has a reactive power regulation function to fully compensate for the three-phase power imbalance. The three-phase voltage source converter compensation device involved in the above embodiment is a common topology structure for AC / DC power conversion in the power grid, and has a certain installation scale, which can reduce a certain investment cost.

[0089] Figure 3 The control framework diagram of the three-phase voltage source converter of the SPTQ control scheme is shown in the figure. x ref is the x-phase active power command value (x=a, b, c), P Sx Indicates the x-phase active power at the transmitting end; P Savg P Sa 、P Sb 、P Sc The average value, P Savg =(P Sa +P Sb +P Sc ) / 3.

[0090] like Figure 3 As shown in Figure 1, the control system has a hierarchical structure consisting of measurement, outer loop, inner loop, and modulation. In the measurement phase, the AC side voltage and current of the three-phase voltage source converter are first measured. A series of data processing steps, including single-phase power measurement, separation of positive and negative sequence components, phase-locked loop, and Park transform, are then performed to ultimately obtain the dq-axis components of the voltage and current. These dq-axis components are then transferred to the control loop. The outer loop is responsible for phase-splitting power regulation and generates command values ​​for the dq-axis components of the positive and negative sequence currents. The ultimate goal of phase-splitting power regulation is to balance the three-phase load at the transmission end and achieve a balanced load across the entire feeder.

[0091] Taking active power balancing as an example, the power command value of each phase can be obtained through the following closed loop as shown in formula (13):

[0092] P x ref =G outer (s)(P Savg -P Sx )+P sumref / 3 (13)

[0093] Where G outer (s) represents the proportional-integral controller of the outer loop.

[0094] The inner loop control ensures that each controlled variable tracks its corresponding command value. Since negative sequence current is involved, a decoupled dual synchronous frame current control scheme is adopted to achieve independent control of the positive and negative sequence dq current components.

[0095] Among them, as shown in formula (14) and formula (15):

[0096]

[0097] Where, v dP ref 、v qP ref 、v dN ref 、v qN ref is the command value of the dq axis component of the three-phase voltage source converter side voltage; G inner (s) represents the proportional-integral controller of the inner loop.

[0098] According to equations (14) and (15), the inner loop outputs the reference voltage on the three-phase voltage source converter side, which is finally converted into the PWM control signal of the three-phase voltage source converter through the SPWM modulation algorithm.

[0099] The above-mentioned three-phase voltage source converter phase-split power control method based on negative-sequence current injection of the present application first obtains the three-phase grid voltage and three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory; then obtains the power calculation formula of the three-phase voltage source converter, and the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter; then, according to the three-phase grid voltage, the three-phase grid current and the power calculation formula, the target relationship formula is determined, and the target relationship formula characterizes the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase and the reactive power of each phase; finally, according to the target relationship formula, the first control method or the second control method is adopted to control the operation of the three-phase voltage source converter, the first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the second control method is a control method for independently controlling the reactive power of each phase and the total active power. This method derives and analyzes the mathematical relationship between single-phase power in the phase domain and the positive and negative sequence components of current, and proposes a new phase-splitting power control strategy for three-phase voltage source converter based on injecting negative sequence current, which realizes independent adjustment of the average power of each phase and achieves the effect of fully compensating for the three-phase imbalance of the distribution network. It solves the problems that the existing three-phase imbalance control methods cannot meet the requirements of independent adjustment of active and reactive power of all phases, cannot achieve the effect of full compensation, and consume large human resources and high costs.

[0100] In the above embodiment, the power information at the power grid transmitting end can be used to calculate the command values ​​of each current component by using the mathematical relationship between single-phase power and each current component, so as to control each phase of the three-phase voltage source converter to independently output different powers. Based on the power imbalance of each phase at the grid end, the three-phase voltage source converter can be independently controlled to output different powers to compensate for it, thereby achieving three-phase power balance on the grid side. The control method used is a negative sequence current injection control method, which has a simple control structure and does not require complex algorithms and solution processes. In addition, due to the high penetration level of the three-phase voltage source converter in the grid, no additional hardware investment is required.

[0101] Example

[0102] Build a three-phase unbalanced system model in Matlab Figure 4 As shown, the model includes a two-level three-phase inverter module (Two-Level Converter), the three-phase unbalanced load is composed of different inductors, and the inductance parameters of phases a, b, and c are L a =20mH, L b =25mH, L c =27mH, C is the capacitance, i a 、i b 、i c are the currents of phases a, b, and c respectively, and e a 、eb 、e c The AC power sources of phases a, b, and c are respectively, R and L are the resistance and inductance of the output filter circuit, R = 0.1Ω, L = 0.01H. The total active and reactive power reference values ​​of the three-phase voltage source converter are P sum ref =30kW, Q sum ref =0kW.

[0103] Taking the SPTQ control scheme as an example, the simulation results of the SPTQ control scheme are as follows: Figure 5 Initially, the three-phase voltage source converter operates in normal mode, and the proposed SPTQ strategy is switched in at t = 0.1s. It can be seen that the single-phase active power P at the grid side is Sa 、P Sb and P Sc Initially, due to the unbalanced three-phase load, the active power of each phase is unbalanced, but it converges quickly after the SPTQ strategy starts running and achieves three-phase power balance. In contrast, the three-phase voltage source converter initially has the same three-phase power P a 、P b 、P c , but they are controlled separately and independently. Due to the inconsistent active power imbalance of each phase at the transmitter, the three-phase voltage source converter outputs different single-phase active powers a, b, and c to achieve inter-phase active power compensation. The effectiveness of the SPTQ control strategy and the effectiveness of phase balance are verified. At the same time, throughout the simulation process, the total active power and reactive power remain constant (30kW, 0kVar), but a 100Hz ripple appears after t=0.2s. This is caused by the coupling between the injected negative-sequence current and the positive-sequence grid voltage. From the current tracking waveform, both the positive and negative sequence dq currents can track their step change commands within 0.06s. Considering the measurement delay of the sequence separation link, this is a performance that meets the requirements.

[0104] The embodiment of the present application also provides a control device for the phase-splitting power of a three-phase voltage source converter based on negative-sequence current injection. It should be noted that the control device for the phase-splitting power of a three-phase voltage source converter based on negative-sequence current injection in the embodiment of the present application can be used to execute the control method for the phase-splitting power of a three-phase voltage source converter based on negative-sequence current injection provided in the embodiment of the present application. The device is used to implement the above-mentioned embodiments and preferred implementation methods, and those that have been explained will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and conceivable.

[0105] The following introduces a control device for the phase-splitting power of a three-phase voltage source converter based on negative-sequence current injection provided in an embodiment of the present application.

[0106] Figure 6 Schematic diagram of a three-phase voltage source converter phase power control device based on negative sequence current injection according to an embodiment of the present application. Figure 6 As shown, the device includes a first acquisition unit 10, a second acquisition unit 20, a determination unit 30 and a control unit 40, wherein the first acquisition unit 10 is used to obtain the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory; the second acquisition unit 20 is used to obtain the power calculation formula of the above-mentioned three-phase voltage source converter, and the above-mentioned power calculation formula is used to calculate the active power of the above-mentioned three-phase voltage source converter and the reactive power of the above-mentioned three-phase voltage source converter; the determination unit 30 is used to determine the target relationship formula according to the above-mentioned three-phase grid voltage, the above-mentioned three-phase grid current and the above-mentioned power calculation formula, and the above-mentioned target relationship formula represents the relationship between the positive sequence voltage, the negative sequence voltage, the positive sequence current, the negative sequence current, the active power of each phase and the reactive power of each phase; the control unit 40 is used to control the operation of the above-mentioned three-phase voltage source converter using the first control method or the second control method according to the above-mentioned target relationship formula, the above-mentioned first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the above-mentioned second control method is a control method for independently controlling the reactive power of each phase and the total active power.

[0107] The above-mentioned three-phase voltage source converter phase-splitting power control device based on negative-sequence current injection of the present application includes a first acquisition unit, a second acquisition unit, a determination unit and a control unit. The first acquisition unit is used to obtain the three-phase grid voltage and three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory; the second acquisition unit is used to obtain the power calculation formula of the three-phase voltage source converter, and the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter; the determination unit is used to determine the target relationship formula based on the three-phase grid voltage, the three-phase grid current and the power calculation formula, and the target relationship formula represents the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase and the reactive power of each phase; the control unit is used to control the operation of the three-phase voltage source converter using the first control method or the second control method according to the target relationship formula. The first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the second control method is a control method for independently controlling the reactive power of each phase and the total active power. By deriving and analyzing the mathematical relationship between single-phase power in the phase domain and the positive and negative sequence components of the current, the device proposes a new phase-splitting power control strategy for the three-phase voltage source converter based on the injection of negative sequence current, which realizes the independent adjustment of the average power of each phase and achieves the effect of fully compensating for the three-phase imbalance of the distribution network. It solves the problem that the existing three-phase imbalance control method cannot meet the requirements of independent adjustment of active and reactive power of all phases, cannot achieve the effect of full compensation, and consumes a lot of human resources and is costly.

[0108] In some embodiments, the control unit includes a first determining module, a second determining module and a first control module, wherein the first determining module is used to determine the total reactive power calculation formula Q of the three-phase voltage source converter. sum =Q a +Q b +Q c , where Q sum is the total reactive power mentioned above, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c The c-phase reactive power is calculated as follows: The second determination module is configured to determine a first command value determination formula based on the total reactive power calculation formula and the target relationship formula, and to determine a first target command value based on the first command value determination formula. The first target command value includes the dq-axis component command values ​​of the positive and negative sequence currents, the active power command values ​​of each phase, and the total reactive power command value. The first control module is configured to control the operation of the three-phase voltage source converter using the first target command value. This allows for automatic phase compensation based on power imbalance, eliminating the need for human intervention and optimization, and provides reactive power regulation.

[0109] In some examples, the second determining module includes a first determining submodule, the first determining submodule being configured to determine the first instruction value determining calculation formula [i dP ref i qP ref i dN ref i qN ref ] T =T P -1 ×[P a ref P b ref P c ref Q sum ref ] T , where i dP ref 、i qP ref 、i dN ref 、i qN ref are the dq axis component command values ​​of the positive and negative sequence current respectively; P a ref 、P b ref 、P c ref are the active power command values ​​of phases a, b, and c respectively; Q sum ref In this way, the first instruction value determination formula can be accurately determined, thereby ensuring the subsequent accurate determination of the positive and negative sequence current dq axis component instruction values, the active power instruction value of each phase, and the total reactive power instruction value.

[0110] In some examples, the control unit includes a third determination module, a fourth determination module and a second control module, wherein the third determination module is used to determine the total active power calculation formula P of the three-phase voltage source converter. sum =P a +P b +P c , where P sum is the total active power mentioned above, P a is the active power of phase a, P b is the active power of phase b, P cThe fourth determination module is configured to determine a second command value determination formula based on the total active power calculation formula and the target relationship formula, and to determine a second target command value based on the second command value determination formula. The second target command value includes reactive power command values ​​for each phase and a total active power command value. The second control module is configured to control the operation of the three-phase voltage source converter using the second target command value. This allows for automatic phase compensation based on power imbalance, eliminating the need for human intervention and optimization. Furthermore, the system provides reactive power regulation and fully compensates for three-phase power imbalance. Furthermore, the three-phase voltage source converter compensation device described in the above embodiment is a common topology for AC / DC power conversion in power grids and has a certain installed base, thus reducing investment costs.

[0111] In this embodiment, the fourth determination module includes a second determination submodule, which is used to determine the second instruction value determination calculation formula [i dP ref i qP ref i dN ref i qN ref ]=T Q -1 [Q a ref Q b ref Q c ref P sum ref ], where Q a ref , Q b ref , Q c ref are the reactive power command values ​​of phases a, b, and c respectively; P sum ref In this way, the second instruction value determination formula can be accurately determined, thereby ensuring the subsequent accurate determination of the reactive power instruction value and the total active power instruction value of each phase.

[0112] In an optional solution, the first acquisition unit includes a first acquisition module and a second acquisition module. The first acquisition module is used to obtain the three-phase grid voltage in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory, wherein the three-phase grid voltage is expressed as in, are the grid voltage phasors of phases a, b, and c respectively; e dP 、e qP 、edN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; the second acquisition module is used to obtain the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory, wherein the three-phase grid current is expressed as in, are the grid current phasors of phases a, b, and c, respectively, i dP 、i qP 、i dN 、i qN The dq components of the positive and negative sequence grid currents are represented respectively. In this way, the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter can be accurately determined.

[0113] As an optional solution, the determination unit includes a determination subunit for determining the target relationship according to the three-phase grid voltage, the three-phase grid current and the power calculation formula. Among them, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase c, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase c, e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; i dP 、i qP 、i dN 、i qN Denote the dq components of the positive and negative sequence grid currents respectively. In this way, the power of the three-phase voltage source converter can be accurately calculated according to the target relationship.

[0114] The above-mentioned three-phase voltage source converter phase-splitting power control device based on negative-sequence current injection includes a processor and a memory. The first acquisition unit and other components are stored as program units in the memory, and the processor executes the program units stored in the memory to implement the corresponding functions. The above-mentioned modules are all located in the same processor; alternatively, the above-mentioned modules can be located in different processors in any combination.

[0115] The processor includes a core, which retrieves the corresponding program unit from the memory. One or more cores can be configured, and by adjusting the core parameters, the system addresses the problem that existing three-phase imbalance management methods cannot meet the requirements of independent regulation of active and reactive power on all phases, cannot achieve full compensation, and consume a lot of human resources and are costly.

[0116] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0117] An embodiment of the present invention provides a computer-readable storage medium, which includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute the above-mentioned method for controlling the phase power of the three-phase voltage source converter based on negative sequence current injection.

[0118] Specifically, a method for controlling the split-phase power of a three-phase voltage source converter based on negative sequence current injection includes:

[0119] Step S201, obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory;

[0120] Step S202, obtaining a power calculation formula of the three-phase voltage source converter, wherein the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter;

[0121] Step S203: determining a target relationship equation based on the three-phase grid voltage, the three-phase grid current, and the power calculation equation, wherein the target relationship equation represents the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase, and the reactive power of each phase;

[0122] Step S204, according to the above-mentioned target relationship, adopt the first control method or the second control method to control the operation of the above-mentioned three-phase voltage source converter, the above-mentioned first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the above-mentioned second control method is a control method for independently controlling the reactive power of each phase and the total active power.

[0123] An embodiment of the present invention provides a processor, which is used to run a program, wherein when the program is run, the method for controlling the phase power of a three-phase voltage source converter based on negative sequence current injection is executed.

[0124] Specifically, a method for controlling the split-phase power of a three-phase voltage source converter based on negative sequence current injection includes:

[0125] Step S201, obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory;

[0126] Step S202, obtaining a power calculation formula of the three-phase voltage source converter, wherein the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter;

[0127] Step S203: determining a target relationship equation based on the three-phase grid voltage, the three-phase grid current, and the power calculation equation, wherein the target relationship equation represents the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase, and the reactive power of each phase;

[0128] Step S204, according to the above-mentioned target relationship, adopt the first control method or the second control method to control the operation of the above-mentioned three-phase voltage source converter, the above-mentioned first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the above-mentioned second control method is a control method for independently controlling the reactive power of each phase and the total active power.

[0129] An embodiment of the present invention provides a device, comprising a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, at least the following steps are performed:

[0130] Step S201, obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory;

[0131] Step S202, obtaining a power calculation formula of the three-phase voltage source converter, wherein the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter;

[0132] Step S203: determining a target relationship equation based on the three-phase grid voltage, the three-phase grid current, and the power calculation equation, wherein the target relationship equation represents the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase, and the reactive power of each phase;

[0133] Step S204, according to the above-mentioned target relationship, adopt the first control method or the second control method to control the operation of the above-mentioned three-phase voltage source converter, the above-mentioned first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the above-mentioned second control method is a control method for independently controlling the reactive power of each phase and the total active power.

[0134] The devices in this article can be servers, PCs, PADs, mobile phones, etc.

[0135] Optionally, according to the target relationship, a first control method is used to control the operation of the three-phase voltage source converter, including: determining a total reactive power calculation formula Q of the three-phase voltage source converter sum =Qa +Q b +Q c , where Q sum is the total reactive power mentioned above, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase C; according to the above-mentioned total reactive power calculation formula and the above-mentioned target relationship formula, the first instruction value determination calculation formula is determined, and according to the above-mentioned first instruction value determination calculation formula, the first target instruction value is determined, and the above-mentioned first target instruction value includes the positive and negative sequence current dq axis component instruction value, the active power instruction value of each phase and the total reactive power instruction value; the above-mentioned first target instruction value is used to control the operation of the above-mentioned three-phase voltage source converter.

[0136] Optionally, determining the first instruction value determination calculation formula according to the above-mentioned total reactive power calculation formula and the above-mentioned target relationship formula includes: determining the first instruction value determination calculation formula [i dP ref i qP ref i dN ref i qN ref ] T =T P -1 ×[P a ref P b ref P c ref Q sum ref ] T , where i dP ref 、i qP ref 、i dN ref 、i qN ref are the dq axis component command values ​​of the positive and negative sequence current respectively; P a ref 、P b ref 、P c ref are the active power command values ​​of phases a, b, and c respectively; Q sum ref are the total reactive power command values ​​respectively.

[0137] Optionally, according to the target relationship, a second control method is used to control the operation of the three-phase voltage source converter, including: determining a total active power calculation formula P of the three-phase voltage source converter sum =P a +P b +P c , where P sum is the total active power mentioned above, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase C; according to the above-mentioned total active power calculation formula and the above-mentioned target relationship formula, the second instruction value determination calculation formula is determined, and according to the above-mentioned second instruction value determination calculation formula, the second target instruction value is determined, and the above-mentioned second target instruction value includes the reactive power instruction value of each phase and the total active power instruction value; the above-mentioned second target instruction value is used to control the operation of the above-mentioned three-phase voltage source converter.

[0138] Optionally, determining the second instruction value determination calculation formula according to the above total active power calculation formula and the above target relationship formula includes: determining the second instruction value determination calculation formula [i dP ref i qP ref i dN ref i qN ref ]=T Q -1 [Q a ref Q b ref Q c ref P sum ref ], where Q a ref , Q b ref , Q c ref are the reactive power command values ​​of phases a, b, and c respectively; P sum ref are the total active power command values ​​respectively.

[0139] Optionally, obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory includes: obtaining the three-phase grid voltage in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory, wherein the three-phase grid voltage is expressed as in, are the grid voltage phasors of phases a, b, and c respectively; edP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; according to the symmetrical component theory, the three-phase grid current in the phasor domain of the three-phase voltage source converter is obtained, where the three-phase grid current is expressed as in, are the grid current phasors of phases a, b, and c, respectively, i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

[0140] Optionally, determining the target relationship according to the three-phase grid voltage, the three-phase grid current and the power calculation formula includes: determining the target relationship according to the three-phase grid voltage, the three-phase grid current and the power calculation formula Among them, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase c, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase c, e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

[0141] The present application also provides a computer program product, which, when executed on a data processing device, is adapted to execute a program for initializing at least the following method steps:

[0142] Step S201, obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory;

[0143] Step S202, obtaining a power calculation formula of the three-phase voltage source converter, wherein the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter;

[0144] Step S203: determining a target relationship equation based on the three-phase grid voltage, the three-phase grid current, and the power calculation equation, wherein the target relationship equation represents the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase, and the reactive power of each phase;

[0145] Step S204, according to the above-mentioned target relationship, adopt the first control method or the second control method to control the operation of the above-mentioned three-phase voltage source converter, the above-mentioned first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the above-mentioned second control method is a control method for independently controlling the reactive power of each phase and the total active power.

[0146] Optionally, according to the target relationship, a first control method is used to control the operation of the three-phase voltage source converter, including: determining a total reactive power calculation formula Q of the three-phase voltage source converter sum =Q a +Q b +Q c , where Q sum is the total reactive power mentioned above, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase C; according to the above-mentioned total reactive power calculation formula and the above-mentioned target relationship formula, the first instruction value determination calculation formula is determined, and according to the above-mentioned first instruction value determination calculation formula, the first target instruction value is determined, and the above-mentioned first target instruction value includes the positive and negative sequence current dq axis component instruction value, the active power instruction value of each phase and the total reactive power instruction value; the above-mentioned first target instruction value is used to control the operation of the above-mentioned three-phase voltage source converter.

[0147] Optionally, determining the first instruction value determination calculation formula according to the above-mentioned total reactive power calculation formula and the above-mentioned target relationship formula includes: determining the first instruction value determination calculation formula [i dP ref i qP ref i dN ref i qN ref ] T =T P -1 ×[P a ref P b ref P c ref Q sum ref ] T , where i dPref 、i qP ref 、i dN ref 、i qN ref are the dq axis component command values ​​of the positive and negative sequence current respectively; P a ref 、P b ref 、P c ref are the active power command values ​​of phases a, b, and c respectively; Q sum ref are the total reactive power command values ​​respectively.

[0148] Optionally, according to the target relationship, a second control method is used to control the operation of the three-phase voltage source converter, including: determining a total active power calculation formula P of the three-phase voltage source converter sum =P a +P b +P c , where P sum is the total active power mentioned above, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase C; according to the above-mentioned total active power calculation formula and the above-mentioned target relationship formula, the second instruction value determination calculation formula is determined, and according to the above-mentioned second instruction value determination calculation formula, the second target instruction value is determined, and the above-mentioned second target instruction value includes the reactive power instruction value of each phase and the total active power instruction value; the above-mentioned second target instruction value is used to control the operation of the above-mentioned three-phase voltage source converter.

[0149] Optionally, determining the second instruction value determination calculation formula according to the above total active power calculation formula and the above target relationship formula includes: determining the second instruction value determination calculation formula [i dP ref i qP ref i dN ref i qN ref ]=T Q -1 [Q a ref Q b ref Q c ref P sum ref ], where Q a ref , Qb ref , Q c ref are the reactive power command values ​​of phases a, b, and c respectively; P sum ref are the total active power command values ​​respectively.

[0150] Optionally, obtaining the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory includes: obtaining the three-phase grid voltage in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory, wherein the three-phase grid voltage is expressed as in, are the grid voltage phasors of phases a, b, and c respectively; e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; according to the symmetrical component theory, the three-phase grid current in the phasor domain of the three-phase voltage source converter is obtained, where the three-phase grid current is expressed as in, are the grid current phasors of phases a, b, and c, respectively, i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

[0151] Optionally, determining the target relationship according to the three-phase grid voltage, the three-phase grid current and the power calculation formula includes: determining the target relationship according to the three-phase grid voltage, the three-phase grid current and the power calculation formula Among them, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase c, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase c, e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

[0152] Obviously, those skilled in the art will appreciate that the various modules or steps of the present invention described above can be implemented using a general-purpose computing device, can be centralized on a single computing device, or can be distributed across a network of multiple computing devices. They can be implemented using program code executable by the computing device, and thus, can be stored in a storage device and executed by the computing device. In some cases, the steps shown or described herein can be performed in a different order than that shown, or can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0153] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0154] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0155] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0156] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0157] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0158] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0159] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory media such as modulated data signals and carrier waves.

[0160] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0161] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0162] 1) The above-mentioned three-phase voltage source converter phase-split power control method based on negative-sequence current injection of the present application first obtains the three-phase grid voltage and three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory; then obtains the power calculation formula of the three-phase voltage source converter, and the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter; then, according to the three-phase grid voltage, the three-phase grid current and the power calculation formula, determines the target relationship formula, and the target relationship formula characterizes the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase and the reactive power of each phase; finally, according to the target relationship formula, the first control method or the second control method is adopted to control the operation of the three-phase voltage source converter, the first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the second control method is a control method for independently controlling the reactive power of each phase and the total active power. This method derives and analyzes the mathematical relationship between single-phase power in the phase domain and the positive and negative sequence components of current, and proposes a new phase-splitting power control strategy for three-phase voltage source converter based on injecting negative sequence current, which realizes independent adjustment of the average power of each phase and achieves the effect of fully compensating for the three-phase imbalance of the distribution network. It solves the problems that the existing three-phase imbalance control methods cannot meet the requirements of independent adjustment of active and reactive power of all phases, cannot achieve the effect of full compensation, and consume large human resources and high costs.

[0163] 2) The above-mentioned three-phase voltage source converter phase-split power control device based on negative-sequence current injection of the present application includes a first acquisition unit, a second acquisition unit, a determination unit and a control unit. The first acquisition unit is used to obtain the three-phase grid voltage and three-phase grid current in the phasor domain of the three-phase voltage source converter according to the symmetrical component theory; the second acquisition unit is used to obtain the power calculation formula of the three-phase voltage source converter, and the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter; the determination unit is used to determine the target relationship formula based on the three-phase grid voltage, the three-phase grid current and the power calculation formula, and the target relationship formula represents the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase and the reactive power of each phase; the control unit is used to control the operation of the three-phase voltage source converter using the first control method or the second control method according to the target relationship formula. The first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the second control method is a control method for independently controlling the reactive power of each phase and the total active power. By deriving and analyzing the mathematical relationship between single-phase power in the phase domain and the positive and negative sequence components of the current, the device proposes a new phase-splitting power control strategy for the three-phase voltage source converter based on the injection of negative sequence current, which realizes the independent adjustment of the average power of each phase and achieves the effect of fully compensating for the three-phase imbalance of the distribution network. It solves the problem that the existing three-phase imbalance control method cannot meet the requirements of independent adjustment of active and reactive power of all phases, cannot achieve the effect of full compensation, and consumes a lot of human resources and is costly.

[0164] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for controlling the phase power of a three-phase voltage source converter based on negative sequence current injection, characterized in that: include: According to the symmetrical component theory, the three-phase grid voltage and the three-phase grid current in the phasor domain of the three-phase voltage source converter are obtained; Obtaining a power calculation formula for the three-phase voltage source converter, wherein the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter; Determine a target relationship formula based on the three-phase grid voltage, the three-phase grid current, and the power calculation formula, wherein the target relationship formula represents the relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase, and the reactive power of each phase; Controlling the operation of the three-phase voltage source converter using a first control method or a second control method according to the target relationship, wherein the first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the second control method is a control method for independently controlling the reactive power of each phase and the total active power; Determining a target relationship according to the three-phase grid voltage, the three-phase grid current, and the power calculation formula includes: Among them, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase c, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase c, e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

2. The control method according to claim 1, characterized in that: Controlling the operation of the three-phase voltage source converter using a first control method according to the target relationship includes: Determine the total reactive power calculation formula Q of the three-phase voltage source converter sum =Q a +Q b +Q c , where Q sum is the total reactive power, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase c; Determining a first command value determination formula based on the total reactive power calculation formula and the target relationship formula, and determining a first target command value based on the first command value determination formula, wherein the first target command value includes a positive and negative sequence current dq axis component command value, an active power command value of each phase, and a total reactive power command value; The operation of the three-phase voltage source converter is controlled by using the first target command value.

3. The control method according to claim 2, characterized in that: Determining a first instruction value determination formula based on the total reactive power calculation formula and the target relationship formula includes: According to the total reactive power calculation formula and the target relationship formula, the first command value determination calculation formula [i dP ref i qP ref i dN ref i qN ref ] T =T P -1 ×[P a ref P b ref P c ref Q sum ref ] T , where i dP ref 、i qP ref 、i dN ref 、i qN ref are the dq axis component command values ​​of the positive and negative sequence current respectively; P a ref 、P b ref 、P c ref are the active power command values ​​of phases a, b, and c respectively; Q sum ref are the total reactive power command values, 4. The control method according to claim 1, wherein: Controlling the operation of the three-phase voltage source converter using a second control method according to the target relationship includes: Determine the total active power calculation formula P of the three-phase voltage source converter sum =P a +P b +P c Among them, P sum is the total active power, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase c; Determining a second command value determination formula based on the total active power calculation formula and the target relationship formula, and determining a second target command value based on the second command value determination formula, wherein the second target command value includes a reactive power command value and a total active power command value for each phase; The second target command value is used to control the operation of the three-phase voltage source converter.

5. The control method according to claim 4, characterized in that: Determining a second instruction value determination formula based on the total active power calculation formula and the target relationship formula includes: According to the total active power calculation formula and the target relationship formula, the second command value determination calculation formula [i dP ref i qP ref i dN ref i qN ref ]=T Q -1 [Q a ref Q b ref Q c ref P sum ref ], where Q a ref , Q b ref , Q c ref are the reactive power command values ​​of phases a, b, and c respectively; P sum ref are the total active power command values, 6. The control method according to claim 1, characterized in that: According to the symmetrical component theory, the three-phase grid voltage and three-phase grid current in the phasor domain of the three-phase voltage source converter are obtained, including: According to the symmetrical component theory, the three-phase grid voltage in the phasor domain of the three-phase voltage source converter is obtained, where the three-phase grid voltage is expressed as Among them, e a 、e b 、e c are the grid voltage phasors of phases a, b, and c respectively; e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; According to the symmetrical component theory, the three-phase grid current in the phasor domain of the three-phase voltage source converter is obtained, wherein the three-phase grid current is expressed as Among them, i a 、i b 、i c are the grid current phasors of phases a, b, and c, respectively, i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

7. A control device for phase-splitting power of a three-phase voltage source converter based on negative sequence current injection, characterized in that: include: A first acquisition unit is configured to acquire a three-phase grid voltage and a three-phase grid current in a phasor domain of a three-phase voltage source converter according to a symmetrical component theory; a second acquiring unit, configured to acquire a power calculation formula of the three-phase voltage source converter, wherein the power calculation formula is used to calculate the active power of the three-phase voltage source converter and the reactive power of the three-phase voltage source converter; a determining unit, configured to determine a target relationship equation based on the three-phase grid voltage, the three-phase grid current, and the power calculation equation, wherein the target relationship equation represents a relationship between the positive-sequence voltage, the negative-sequence voltage, the positive-sequence current, the negative-sequence current, the active power of each phase, and the reactive power of each phase; a control unit, configured to control the operation of the three-phase voltage source converter using a first control method or a second control method according to the target relationship, wherein the first control method is a control method for independently controlling the active power of each phase and the total reactive power, and the second control method is a control method for independently controlling the reactive power of each phase and the total active power; The determining unit includes a determining subunit for determining the target relationship according to the three-phase grid voltage, the three-phase grid current and the power calculation formula. Among them, P a is the active power of phase a, P b is the active power of phase b, P c is the active power of phase c, Q a is the reactive power of phase a, Q b is the reactive power of phase b, Q c is the reactive power of phase c, e dP 、e qP 、e dN 、e qN Represent the dq components of the positive and negative sequence grid voltages respectively; i dP 、i qP 、i dN 、i qN Represent the dq components of the positive and negative sequence grid currents respectively.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium includes a stored program, wherein, when the program is running, the device where the computer-readable storage medium is located is controlled to execute the method for controlling the phase power of a three-phase voltage source converter based on negative sequence current injection as described in any one of claims 1 to 6.

9. An electronic device, characterized in that: include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and are configured to be executed by the one or more processors, and the one or more programs include a method for controlling the phase power of a three-phase voltage source converter based on negative sequence current injection according to any one of claims 1 to 6.

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