Direct-current bus fractional order control method of transformer area interconnection device and related device

Abstract

The invention belongs to the technical field of power grid automation, and particularly relates to a direct-current bus fractional order control method of a transformer area interconnection device and a related device. According to the fractional order control method, the fractional order mathematical model of the AC-DC converter is established based on the topological structure of the AC-DC converter of the transformer area flexible interconnection equipment, the design of the fractional order current inner loop controller is carried out, and the accuracy and the stability of current inner loop tracking are improved. Based on a fractional order mathematical model of an AC-DC converter, an active disturbance rejection control strategy acts on control of a voltage outer loop so as to realize stable and accurate voltage tracking.

Description

Technical Field

[0001] The present invention belongs to the technical field of power grid automation, and in particular relates to a direct current bus fractional-order control method and a related device of a substation interconnection device. Background Art

[0002] The substation interconnection device is generally composed of two AC-DC converters in a back-to-back manner, including two AC interfaces and one DC bus interface. The DC bus interface can also be expanded to connect to DC devices such as photovoltaics, energy storage and charging piles. Under certain working conditions, the DC bus voltage needs to be dynamically adjusted to meet a wider range of DC voltage input. Therefore, stable, accurate and fast tracking and control of the DC bus is very important. Normally, the DC bus voltage of the substation interconnection device is controlled by an AC-DC converter.

[0003] Common methods include the dual closed-loop control method of DC voltage outer loop + current inner loop, and the accurate and effective control of DC bus voltage by adding feedforward and other methods. From the calculation of the dual closed-loop control parameters, it can be seen that this method is more suitable for the case where the DC bus voltage set value is a fixed value. When the DC bus set value voltage fluctuates over a large range, the stability, accuracy and speed of the dual closed-loop control still need to be improved. Summary of the invention

[0004] The purpose of the present invention is to provide a DC bus fractional-order control method and related devices for a station area interconnection device to solve the problems in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a DC bus fractional-order control method for a transformer interconnection device, comprising the following steps:

[0007] Step 1: determine the topology of the AC-DC converter of the flexible interconnection device in the substation, and construct a fractional-order mathematical model of the flexible interconnection device in the substation based on the topology;

[0008] Step 2, using the spatial state equation of the fractional-order mathematical model obtained in step 1 as the state equation of the continuous control object;

[0009] Step 3: Determine a fractional-order control strategy for dynamic transformation of the DC bus according to the state equation and operation requirements of the continuous control object; wherein the fractional-order control strategy includes a DC voltage outer loop and a power inner loop.

[0010] Furthermore, in the step of obtaining the pre-built fractional-order mathematical model of the flexible interconnection device in the substation, the fractional-order mathematical model of the flexible interconnection device in the substation is expressed in the three-phase stationary coordinate system abc as follows:

[0011]

[0012] Among them, L 1α1 represents the fractional inductance value of the filter inductor L1 on the first AC side, L 2α2 represents the fractional inductance value of the filter inductor L2 on the second AC side; C β represents the fractional capacitance value on the DC side; α1 and α2 are the order variables of the first and second fractional inductances on the AC side, respectively; β is the order variable of the fractional capacitance; i 1abc 、i 2abc are the three-phase inflow current of the first AC side and the three-phase outflow current of the second AC side respectively; u dc Indicates the voltage value across the DC capacitor; E abc is the three-phase voltage on the left side of the power grid; R1 and R2 are the equivalent resistances on the wires respectively; V abc is the three-phase voltage on the right side of the power grid; m iabc =Ts iabc , Subscript i = 1 or 2; s 1abc 、s 2abc Represent the three-phase switching functions of the first and second AC sides respectively.

[0013] Furthermore, the fractional-order mathematical model of the flexible interconnection device in the three-phase stationary coordinate system abc is transformed into a fractional-order 2 / 3 model, and the fractional-order mathematical model of the flexible interconnection device in the two-phase stationary coordinate system DQ is obtained:

[0014]

[0015] Among them, i 1DQ represents the D and Q components of the three-phase inflow current on the first AC side in the two-phase stationary coordinate system; i 2DQ represents the D and Q components of the three-phase outflow current on the second AC side in the two-phase stationary coordinate system; E DQ It represents the D and Q components of the three-phase voltage on the left side of the power grid in the two-phase stationary coordinate system; V DQ represents the D and Q components of the three-phase voltage on the right side of the power grid in the two-phase stationary coordinate system; s 1DQ 、s 2DQ Respectively represent the D and Q components of the three-phase switching functions of the first and second AC sides.

[0016] Furthermore, the fractional-order mathematical model of the flexible interconnection device in the two-phase stationary coordinate system DQ is transformed into a dq transform to obtain the fractional-order mathematical model of the two-phase rotating coordinate system:

[0017]

[0018] Among them, i 1dqrepresents the d and q components of the three-phase inflow current on the first AC side in the two-phase stationary coordinate system; i 2dq represents the d and q components of the three-phase outflow current on the second AC side in the two-phase stationary coordinate system; s 1dq 、s 2dq Respectively represent the d and q components of the three-phase switching function of the first and second AC sides; ω is the grid voltage angular frequency; E dq represents the d and q components of the three-phase voltage on the left side of the power grid in the two-phase stationary coordinate system; V dq It represents the d and q components of the three-phase voltage on the right side of the power grid in the two-phase stationary coordinate system.

[0019] Furthermore, the inductance order of the fractional-order stage flexible interconnect device is α1=α2=0.85, and the capacitance order is β=0.95.

[0020] Furthermore, according to the state equation and operation requirements of the continuous control object, a fractional-order control strategy for the dynamic transformation of the DC bus is determined, including:

[0021] According to the active power reference value P * and reactive power reference value Q * , calculate the d-axis current reference value respectively D-axis current reference value The difference between the DC side voltage Udc and the DC side voltage reference value Udc* is used as the input of the DC side PI controller. λ The fractional-order controller outputs the active current command; the phase θ of the three-phase voltage on the AC side is extracted through the phase-locked loop circuit; the current on the AC side is transformed into dq based on the phase θ to obtain the d and q components of the three-phase current respectively; the d-axis component of the three-phase current is compared with the DC side PI λ The fractional-order controller outputs active current command or d-axis current reference value Difference is made between the q-axis component of the three-phase current and the d-axis current reference value Difference, the result of difference is input into the first PI λ Fractional-order controller, second PI λ Fractional Order Controller; First PI λ The output of the fractional-order controller is subtracted from the instantaneous value of the d-axis component of the three-phase current to obtain the first difference component, and the second PI λ The output result of the fractional-order controller is subtracted from the instantaneous value of the q-axis component of the three-phase current to obtain the second difference component. The two difference components are superimposed on the result of inverse dq transformation based on the phase θ, and the result of the inverse dq transformation is modulated by SVPWM as a switching instruction.

[0022] Furthermore, PI λ The transfer function of the fractional-order controller is:

[0023]

[0024] Where λ is the current loop integration order, K ip is the current loop proportionality coefficient, K ii is the current loop integral coefficient;

[0025] The open-loop transfer function of the inner current loop is:

[0026]

[0027] Among them, K PWM is the inverter bridge proportional gain, T i is the current signal sampling delay, L is the filter inductance, and R is the comprehensive equivalent resistance;

[0028] The open-loop transfer function of the voltage outer loop is:

[0029]

[0030] Where λ is the voltage loop integration order, T v is the voltage signal sampling delay, and C is the DC side filter capacitor.

[0031] A second aspect of the present invention provides a DC bus fractional-order control device for a substation interconnection device, comprising:

[0032] The first determination module is used to determine the topological structure of the AC-DC converter of the flexible interconnection device in the substation area, and to construct a fractional-order mathematical model of the flexible interconnection device in the substation area based on the topological structure;

[0033] A second determination module is used to determine that the spatial state equation of the fractional-order mathematical model is the state equation of the continuous control object;

[0034] The strategy formulation module is used to determine the fractional-order control strategy of the dynamic transformation of the DC bus according to the state equation and operation requirements of the continuous control object; wherein the fractional-order control strategy includes a DC voltage outer loop and a power inner loop.

[0035] According to a third aspect of the present invention, there is provided an electronic device, comprising a processor and a memory, wherein the processor is configured to execute a computer program stored in the memory to implement the DC bus fractional-order control method of the substation interconnection device as described above.

[0036] According to a fourth aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by a processor, the DC bus fractional-order control method of the substation interconnection device as described above is implemented.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] The present invention proposes a fractional-order control method for the DC bus of a substation interconnection device. Based on the topological structure of the AC-DC converter of the substation flexible interconnection device, a fractional-order mathematical model of the AC-DC converter is established, and a fractional-order current inner loop controller is designed to improve the accuracy and stability of the current inner loop tracking. Based on the fractional-order mathematical model of the AC-DC converter, the self-disturbance rejection control strategy is applied to the control of the voltage outer loop to achieve stable and accurate voltage tracking. The fractional-order control device, electronic device and computer-readable storage medium of the DC bus of a substation interconnection device provided by the present invention also solve the problems raised in the background technology section. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0040] Figure 1 It is a system structure diagram of a flexible interconnection device of a substation based on a fractional-order controller in an embodiment of the present invention;

[0041] Figure 2 It is a fractional-order control structure diagram of the flexible interconnection equipment system in the substation in an embodiment of the present invention;

[0042] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0043] Figure 4 for Figure 2 Enlarged view of point B in the middle;

[0044] Figure 5 This is a diagram of the current inner loop control structure in an embodiment of the present invention;

[0045] Figure 6 This is a structural diagram of a fractional-order voltage outer loop control in an embodiment of the present invention;

[0046] Figure 7 This is a structural block diagram of a DC bus fractional-order control device of a substation interconnection device according to an embodiment of the present invention;

[0047] Figure 8 The present invention is a structural block diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0049] The following detailed description is an exemplary description, which is intended to provide further detailed description of the present invention. Unless otherwise specified, all technical terms used in the present invention have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used in the present invention are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present invention.

[0050] Example 1

[0051] The DC bus fractional-order control method of the substation interconnection device proposed in the present invention is based on the substation flexible interconnection device. The substation flexible interconnection device is mainly composed of back-to-back AC-DC converters, including an AC circuit, a switching circuit and a DC link. Its topological structure is as follows: Figure 1 To simplify the analysis, the following assumptions are made for the AC-DC converter model:

[0052] (1) The power tube is an ideal component and realizes the full flow of energy in the working state;

[0053] (2) The three-phase circuit of the AC-DC converter is completely symmetrical and the parameters are consistent;

[0054] (3) The switching frequency of the power tube is much greater than the grid frequency, and the dead zone and transition process are not considered.

[0055] AC-DC converters are key devices for realizing flexible interconnection of substations. Inductors and capacitors are key components of AC-DC converters. Their performance directly determines the maximum transfer energy and the quality of the transferred energy. In order to describe the electrical characteristics of inductors and capacitors with fractional-order characteristics, a more accurate and flexible fractional-order model needs to be established.

[0056] A fractional-order control method for a DC bus of a transformer interconnection device according to an embodiment of the present invention comprises the following steps:

[0057] Step 1: Determine the topological structure of the AC-DC converter of the flexible interconnection device in the substation, and based on the topological structure, construct a fractional-order mathematical model of the flexible interconnection device in the substation; use the spatial state equation of the fractional-order mathematical model as the state equation of the continuous control object.

[0058] Specifically, for the flexible interconnection device in the substation, its circuit topology is analyzed, and a fractional-order mathematical model is established. The system structure of the flexible interconnection device in the substation based on the fractional-order controller is as follows: Figure 1 The fractional-order mathematical model of the flexible interconnection device in the three-phase stationary coordinate system abc is:

[0059]

[0060] Among them, α is the fractional inductor order variable, β is the fractional capacitor order variable; L1, L2 represent the filter inductor, L 1α1 Indicates the fractional inductance value of L1, i.e., the pseudo inductance value, L 2α2 represents the fractional inductance value of L2; i1 and i2 are the inflow currents on the feeder 1 side and feeder 2 side respectively; E abc is the voltage on the left side of the grid, V abc is the voltage on the right side of the power grid; R1 and R2 are the equivalent resistances on the wire; m iabc =Ts iabc Indicates the state of the switch tube. C β Indicates the fractional inductance value, i.e. pseudo inductance value, u dc represents the DC side voltage value, s1 and s2 represent the switching function.

[0061] Among them, L 1α1 represents the fractional inductance value of the filter inductor L1 on the first AC side, L 2α2 represents the fractional inductance value of the filter inductor L2 on the second AC side; C β represents the fractional capacitance value on the DC side; α1 and α2 are the order variables of the first and second fractional inductances on the AC side, respectively; β is the order variable of the fractional capacitance; i 1abc 、i 2abc are the three-phase inflow current of the first AC side and the three-phase outflow current of the second AC side respectively; u dc Indicates the voltage value across the DC capacitor; E abc is the three-phase voltage on the left side of the power grid; R1 and R2 are the equivalent resistances on the wires respectively; V abc is the three-phase voltage on the right side of the power grid; m iabc =Ts iabc , Subscript i = 1 or 2; s 1abc 、s 2abc Represent the three-phase switching functions of the first and second AC sides respectively.

[0062] By performing a fractional-order 2 / 3 transformation on the fractional-order mathematical model of the flexible interconnection device in the three-phase stationary coordinate system abc, the fractional-order mathematical model of the flexible interconnection device in the two-phase stationary coordinate system DQ can be obtained:

[0063]

[0064] Among them, i 1DQ represents the D and Q components of the three-phase inflow current on the first AC side in the two-phase stationary coordinate system; i 2DQ represents the D and Q components of the three-phase outflow current on the second AC side in the two-phase stationary coordinate system; E DQ It represents the D and Q components of the three-phase voltage on the left side of the power grid in the two-phase stationary coordinate system; VDQ represents the D and Q components of the three-phase voltage on the right side of the power grid in the two-phase stationary coordinate system; s 1DQ 、s 2DQ Respectively represent the D and Q components of the three-phase switching functions of the first and second AC sides.

[0065] The fractional-order mathematical model of the flexible interconnection device in the DQ lower stage of the two-phase stationary coordinate system is transformed into a dq transform to obtain the fractional-order mathematical model of the two-phase rotating coordinate system:

[0066]

[0067] Among them, i 1dq represents the d and q components of the three-phase inflow current on the first AC side in the two-phase stationary coordinate system; i 2dq represents the d and q components of the three-phase outflow current on the second AC side in the two-phase stationary coordinate system; s 1dq 、s 2dq Respectively represent the d and q components of the three-phase switching function of the first and second AC sides; ω is the grid voltage angular frequency; E dq represents the d and q components of the three-phase voltage on the left side of the power grid in the two-phase stationary coordinate system; V dq It represents the d and q components of the three-phase voltage on the right side of the power grid in the two-phase stationary coordinate system.

[0068] In order to ensure better dynamic characteristics of the busbar, the inductance order of the fractional-order flexible interconnection device is α=0.85, and the fractional-order capacitance order is β=0.95.

[0069] The above steps establish a fractional-order mathematical model of the flexible interconnection device in the substation, and can obtain a mathematical model that can accurately reflect the dynamic characteristics of the DC bus of the flexible interconnection device in the substation, as well as a two-phase rotating coordinate system model of the LC filter.

[0070] Step 2: Determine the fractional-order control strategy for the dynamic transformation of the DC bus according to the state equation and operation requirements of the continuous control object; wherein the fractional-order control strategy includes a DC voltage outer loop and a power inner loop.

[0071] Specifically, the fractional-order control structure diagram of the flexible interconnected equipment system in the substation is as follows: Figure 2 As shown, Figure 3 and Figure 4 They are Figure 2 The enlarged view of A and B in the figure. According to the active power reference value P * and reactive power reference value Q * , calculate the d-axis current reference value respectively D-axis current reference value The difference between the DC side voltage Udc and the DC side voltage reference value Udc* is used as the input of the DC side PI controller. λThe fractional-order controller outputs the active current command; the phase θ of the three-phase voltage on the AC side is extracted through the phase-locked loop circuit; the current on the AC side is transformed into dq based on the phase θ to obtain the d and q components of the three-phase current respectively; the d-axis component of the three-phase current is compared with the DC side PI λ The fractional-order controller outputs active current command or d-axis current reference value Difference is made between the q-axis component of the three-phase current and the d-axis current reference value Difference, the result of difference is input into the first PI λ Fractional-order controller, second PI λ Fractional Order Controller; First PI λ The output of the fractional-order controller is subtracted from the instantaneous value of the d-axis component of the three-phase current to obtain the first difference component, and the second PI λ The output result of the fractional-order controller is subtracted from the instantaneous value of the q-axis component of the three-phase current to obtain the second difference component. The two difference components are superimposed on the result of inverse dq transformation based on the phase θ, and the result of the inverse dq transformation is modulated by SVPWM as a switching instruction.

[0072] The DC voltage outer loop uses the DC side voltage as input and the active current command as output. The minimum beat controller is used to observe the current of the power module as feedforward. The superimposed DC voltage closed loop is generated using PI λ The fractional-order controller obtains the control law of the flexible interconnection device and realizes the variable and precise control of the DC bus of the flexible interconnection device.

[0073] The power inner loop is divided into active power and reactive power loop.

[0074] The flexible interconnection equipment system in the substation adopts SVPWM modulation, and the current inner loop control structure is as follows Figure 5 As shown:

[0075] PI λ The transfer function of the fractional-order controller is:

[0076]

[0077] Where λ is the current loop integration order, K ip is the current loop proportionality coefficient, K ii is the current loop integration coefficient.

[0078] The open-loop transfer function of the inner current loop is:

[0079]

[0080] Among them, K PWM is the inverter bridge proportional gain, T i is the current signal sampling delay, L is the filter inductance, and R is the comprehensive equivalent resistance.

[0081] The fractional-order voltage outer loop control structure is as follows: Figure 6 As shown:

[0082] Bring in PI λ , the open-loop transfer function of the voltage outer loop is calculated as:

[0083]

[0084] Where λ is the voltage loop integration order, T v is the voltage signal sampling delay, and C is the DC side filter capacitor.

[0085] The fractional-order control method of a DC bus of a substation interconnection device proposed in the present invention can improve the control accuracy of the DC bus voltage.

[0086] Reference Figure 2 As shown, according to the active power reference value P * and reactive power reference value Q * , calculate the d-axis current reference value respectively D-axis current reference value The difference between the DC side voltage Udc and the DC side voltage reference value Udc* is used as the input of the DC side PI controller, and the DC side PI controller outputs an active current command; the phase θ and frequency f of the three-phase voltage on the AC side are extracted through the phase-locked loop circuit; the current on the AC side is transformed into dq based on the phase θ and frequency f to obtain the d and q components of the three-phase current respectively; the d-axis component of the three-phase current is compared with the active current command or d-axis current reference value output by the DC side PI controller Difference is made between the q-axis component of the three-phase current and the d-axis current reference value The difference is made, and the difference results are input into the first PI controller and the second PI controller respectively; the output result of the first PI controller is subtracted from the instantaneous value of the d-axis component of the three-phase current to obtain a first difference component, and the output result of the second PI controller is subtracted from the instantaneous value of the q-axis component of the three-phase current to obtain a second difference component, and the two difference components are superimposed on the result of inverse dq transformation based on the phase θ, and the result of the inverse dq transformation is modulated by SVPWM as a switching instruction.

[0087] Example 2

[0088] like Figure 7 As shown, based on the same inventive concept as the above embodiment, the present invention also provides a DC bus fractional-order control device of a substation interconnection device, comprising:

[0089] The first determination module is used to determine the topological structure of the AC-DC converter of the flexible interconnection device in the substation area, and to construct a fractional-order mathematical model of the flexible interconnection device in the substation area based on the topological structure;

[0090] A second determination module is used to determine that the spatial state equation of the fractional-order mathematical model is the state equation of the continuous control object;

[0091] The strategy formulation module is used to determine the fractional-order control strategy of the dynamic transformation of the DC bus according to the state equation and operation requirements of the continuous control object; wherein the fractional-order control strategy includes a DC voltage outer loop and a power inner loop.

[0092] Example 3

[0093] like Figure 8 As shown, the present invention also provides an electronic device 100 for implementing a DC bus fractional-order control method of a substation interconnection device in the above embodiment;

[0094] The electronic device 100 includes a memory 101 , at least one processor 102 , a computer program 103 stored in the memory 101 and executable on the at least one processor 102 , and at least one communication bus 104 .

[0095] The memory 101 can be used to store a computer program 103. The processor 102 implements the steps of a DC bus fractional-order control method of a substation interconnection device in Example 1 by running or executing the computer program stored in the memory 101 and calling the data stored in the memory 101.

[0096] The memory 101 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data (such as audio data) created according to the use of the electronic device 100, etc. In addition, the memory 101 may include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other non-volatile solid-state storage devices.

[0097] At least one processor 102 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor 102 may be a microprocessor or any conventional processor, etc. The processor 102 is the control center of the electronic device 100, and uses various interfaces and lines to connect various parts of the entire electronic device 100.

[0098] The memory 101 in the electronic device 100 stores a plurality of instructions to implement a DC bus fractional-order control method for a substation interconnection device, and the processor 102 can execute the plurality of instructions to implement:

[0099] Obtain a pre-built fractional-order mathematical model of a flexible interconnection device in a substation;

[0100] Determine the operational requirements of the flexible interconnection device in the substation area;

[0101] According to the fractional-order mathematical model and operation requirements of the substation flexible interconnection device, a fractional-order control strategy for dynamic transformation of the DC bus is determined; wherein the fractional-order control strategy for dynamic transformation of the DC bus includes a DC voltage outer loop and a power inner loop.

[0102] Example 4

[0103] If the module / unit integrated in the electronic device 100 is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. Computer-readable media may include: any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory and read-only memory (ROM, Read-Only Memory).

[0104] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0105] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks 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 processes in the flowchart and / or block diagram. 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.

[0106] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate 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 A function specified in one or more boxes.

[0107] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0108] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A DC bus fractional-order control method for a substation interconnection device, characterized in that: The steps include: Determine the topological structure of the AC-DC converter of the flexible interconnection device in the substation area, and construct a fractional-order mathematical model of the flexible interconnection device in the substation area based on the topological structure; Determine the spatial state equation of the fractional-order mathematical model as the state equation of the continuous control object; According to the state equation and operation requirements of the continuous control object, a fractional-order control strategy for the dynamic transformation of the DC bus is determined; wherein the fractional-order control strategy includes a DC voltage outer loop and a power inner loop.

2. The DC bus fractional-order control method of the substation interconnection device according to claim 1 is characterized in that: In the step of obtaining the pre-built fractional-order mathematical model of the flexible interconnection device in the substation, the fractional-order mathematical model of the flexible interconnection device in the substation is expressed in the three-phase stationary coordinate system abc as follows: Among them, L 1α1 represents the fractional inductance value of the filter inductor L1 on the first AC side, L 2α2 represents the fractional inductance value of the filter inductor L2 on the second AC side; C β represents the fractional capacitance value on the DC side; α1 and α2 are the order variables of the first and second fractional inductances on the AC side, respectively; β is the order variable of the fractional capacitance; i 1abc 、i 2abc are the three-phase inflow current of the first AC side and the three-phase outflow current of the second AC side respectively; u dc Indicates the voltage value across the DC capacitor; E abc is the three-phase voltage on the left side of the power grid; R1 and R2 are the equivalent resistances on the wires respectively; V abc is the three-phase voltage on the right side of the power grid; m iabc =Ts iabc , Subscript i = 1 or 2; s 1abc 、s 2abc Represent the three-phase switching functions of the first and second AC sides respectively.

3. The DC bus fractional-order control method of the substation interconnection device according to claim 2 is characterized in that: The fractional-order mathematical model of the flexible interconnection device in the three-phase stationary coordinate system abc is transformed into a fractional-order 2 / 3 model, and the fractional-order mathematical model of the flexible interconnection device in the two-phase stationary coordinate system DQ is obtained: Among them, i 1DQ represents the D and Q components of the three-phase inflow current on the first AC side in the two-phase stationary coordinate system; i 2DQ represents the D and Q components of the three-phase outflow current on the second AC side in the two-phase stationary coordinate system; E DQ It represents the D and Q components of the three-phase voltage on the left side of the power grid in the two-phase stationary coordinate system; V DQ represents the D and Q components of the three-phase voltage on the right side of the power grid in the two-phase stationary coordinate system; s 1DQ 、s 2DQ Respectively represent the D and Q components of the three-phase switching functions of the first and second AC sides.

4. The DC bus fractional-order control method of the substation interconnection device according to claim 3 is characterized in that: The fractional-order mathematical model of the flexible interconnection device in the DQ lower stage of the two-phase stationary coordinate system is transformed into a dq transform to obtain the fractional-order mathematical model of the two-phase rotating coordinate system: Among them, i 1dq represents the d and q components of the three-phase inflow current on the first AC side in the two-phase stationary coordinate system; i 2dq represents the d and q components of the three-phase outflow current on the second AC side in the two-phase stationary coordinate system; s 1dq 、s 2dq Respectively represent the d and q components of the three-phase switching function of the first and second AC sides; ω is the grid voltage angular frequency; E dq represents the d and q components of the three-phase voltage on the left side of the power grid in the two-phase stationary coordinate system; V dq It represents the d and q components of the three-phase voltage on the right side of the power grid in the two-phase stationary coordinate system.

5. The DC bus fractional-order control method of the substation interconnection device according to claim 4 is characterized in that: The inductance order of the fractional-order stage flexible interconnect device is α1=α2=0.85, and the capacitance order is β=0.

95.

6. The DC bus fractional-order control method of the substation interconnection device according to claim 1, characterized in that: According to the state equation and operation requirements of the continuous control object, the fractional-order control strategy for the dynamic transformation of the DC bus is determined, including: According to the active power reference value P * and reactive power reference value Q * , calculate the d-axis current reference value respectively D-axis current reference value The difference between the DC side voltage Udc and the DC side voltage reference value Udc* is used as the input of the DC side PI controller. λ The fractional-order controller outputs the active current command; the phase θ of the three-phase voltage on the AC side is extracted through the phase-locked loop circuit; the current on the AC side is transformed into dq based on the phase θ to obtain the d and q components of the three-phase current respectively; the d-axis component of the three-phase current is compared with the DC side PI λ The fractional-order controller outputs active current command or d-axis current reference value Difference is made between the q-axis component of the three-phase current and the d-axis current reference value Difference, the result of difference is input into the first PI λ Fractional-order controller, second PI λ Fractional Order Controller; First PI λ The output of the fractional-order controller is subtracted from the instantaneous value of the d-axis component of the three-phase current to obtain the first difference component, and the second PI λ The output result of the fractional-order controller is subtracted from the instantaneous value of the q-axis component of the three-phase current to obtain the second difference component. The two difference components are superimposed on the result of inverse dq transformation based on the phase θ, and the result of the inverse dq transformation is modulated by SVPWM as a switching instruction.

7. The DC bus fractional-order control method of the substation interconnection device according to claim 6 is characterized in that: PI λ The transfer function of the fractional-order controller is: Where λ is the current loop integration order, K ip is the current loop proportionality coefficient, K ii is the current loop integral coefficient; The open-loop transfer function of the inner current loop is: Among them, K PWM is the inverter bridge proportional gain, T i is the current signal sampling delay, L is the filter inductance, and R is the comprehensive equivalent resistance; The open-loop transfer function of the voltage outer loop is: Where λ is the voltage loop integration order, T v is the voltage signal sampling delay, and C is the DC side filter capacitor.

8. A DC bus fractional-order control device for a substation interconnection device, characterized in that: include: The first determination module is used to determine the topological structure of the AC-DC converter of the flexible interconnection device in the substation area, and to construct a fractional-order mathematical model of the flexible interconnection device in the substation area based on the topological structure; A second determination module is used to determine that the spatial state equation of the fractional-order mathematical model is the state equation of the continuous control object; The strategy formulation module is used to determine the fractional-order control strategy of the dynamic transformation of the DC bus according to the state equation and operation requirements of the continuous control object; wherein the fractional-order control strategy includes a DC voltage outer loop and a power inner loop.

9. An electronic device, characterized in that: It comprises a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the DC bus fractional-order control method of the substation interconnection device as claimed in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one instruction, and when the at least one instruction is executed by the processor, the DC bus fractional-order control method of the substation interconnection device according to any one of claims 1 to 7 is implemented.

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