Networking type new energy power setting method and system based on phasor geometry

Abstract

The invention discloses a network construction type new energy power setting method and system based on phasor geometry, and belongs to the technical field of new energy grid-connected control. The method comprises the following steps: acquiring parameters during steady-state operation and parameters during a fault of the network construction type new energy, and constructing a power flow-based phasor geometric model on the basis of the parameters during the steady-state operation and the parameters during the fault; based on the phasor geometric model, establishing a phasor geometric diagram of the network construction type new energy during a fault period, and extracting a phasor geometric relationship in the phasor geometric diagram; and based on the geometrical relationship, constructing a power setting model, and based on the power setting model, setting the power during the fault period of the network construction type new energy. According to the method, the parameters after the network-forming type new energy fault can be effectively set.

Description

Technical Field

[0001] The present invention relates to the field of renewable energy grid-connected control technology, and more specifically, to a grid-connected renewable energy power setting method and system based on phasor geometry. Background Art

[0002] Traditional renewable energy sources use a grid-following control strategy. While these technologies exhibit current source characteristics (controlling the grid-connected current), they also have poor inertia and damping properties, resulting in insufficient grid inertia. To improve renewable energy's ability to support grid inertia, the current solution is to integrate these technologies using a grid-building control strategy. These technologies exhibit voltage source characteristics (controlling the grid-connected voltage).

[0003] During a grid fault, the fault current of connected renewable energy systems rises significantly. Since these systems rely on power electronic converters for grid connection, their ability to withstand overcurrent is poor. This can easily cause them to disconnect from the grid during a fault, potentially damaging connected equipment. However, guidelines for connecting renewable energy systems to the grid require that they maintain continuous operation within a certain voltage drop level and duration, demonstrating a certain level of fault ride-through capability. However, since grid-connected renewable energy systems struggle to control their grid current, fault ride-through control is challenging.

[0004] The current fault ride-through strategy for grid-connected renewable energy sources is to add a current control link to the inner loop of the grid-connected control system, achieving fault ride-through through current limiting or constant current control. However, this fault ride-through approach first requires modifications to the grid-connected control link, which introduces control delays and reduces control system stability. Secondly, the forced current limiting control strategy reduces the power angle stability of the grid-connected renewable energy sources. The constant current control strategy is essentially a grid-following control strategy, resulting in the grid-connected renewable energy sources being unable to support grid operation during a fault. Summary of the Invention

[0005] To address the above issues, the present invention proposes a grid-connected renewable energy power setting method based on phasor geometry, comprising:

[0006] Obtaining parameters of the grid-forming new energy during steady-state operation and parameters during a fault, and constructing a phasor geometric model based on power flow based on the parameters during steady-state operation and the parameters during a fault;

[0007] Based on the phasor geometry model, a phasor geometry diagram of the grid-type new energy during a fault period is established, and a phasor geometry relationship in the phasor geometry diagram is extracted;

[0008] Based on the geometric relationship, a power setting model is constructed, and based on the power setting model, the power during the grid-connected new energy fault is set.

[0009] Optional parameters of the grid-forming new energy during steady-state operation include: PCC point voltage, grid-forming converter output voltage, and line impedance, with PCC point voltage as orientation;

[0010] The parameters of the grid-connected new energy failure include: the voltage drop at the PCC point, which is oriented towards the PCC point voltage.

[0011] Optional, phasor geometry model, as follows:

[0012]

[0013] Among them, R s is the grid resistance, ρ is the resistance-to-inductance ratio, k is the grid strength, X s is the grid inductance.

[0014] Optional power setting model, including:

[0015]

[0016] Among them, P1 is the active power injected into the grid by the grid-forming new energy, k is the grid strength, U g1 is the grid voltage after the fault, δ is the power angle (the angle between the grid voltage and the PCC point voltage), α1 is the angle of grid voltage change after the fault, Q1 is the reactive power injected into the grid by the grid-forming renewable energy, and ρ is the resistance-inductance ratio.

[0017] On the other hand, the present invention also proposes a grid-type new energy power setting system based on phasor geometry, comprising:

[0018] An initialization unit is used to obtain parameters of the grid-forming new energy during steady-state operation and parameters during fault conditions, and to construct a phasor geometric model based on power flow based on the parameters during steady-state operation and the parameters during fault conditions;

[0019] a calculation unit, configured to establish a phasor geometry diagram of the grid-forming new energy during a fault period based on the phasor geometry model, and extract a phasor geometry relationship in the phasor geometry diagram;

[0020] The setting unit is used to construct a power setting model based on the geometric relationship, and to set the power during the grid-connected new energy fault based on the power setting model.

[0021] Optional parameters of the grid-forming new energy during steady-state operation include: PCC point voltage, grid-forming converter output voltage, and line impedance, with PCC point voltage as orientation;

[0022] The parameters of the grid-connected new energy failure include: the voltage drop at the PCC point, which is oriented towards the PCC point voltage.

[0023] Optional, phasor geometry model, as follows:

[0024]

[0025] Among them, P1 is the active power injected into the grid by the grid-forming new energy, k is the grid strength, U g1 is the grid voltage after the fault, δ is the power angle (the angle between the grid voltage and the PCC point voltage), α1 is the angle of grid voltage change after the fault, Q1 is the reactive power injected into the grid by the grid-forming renewable energy, and ρ is the resistance-inductance ratio.

[0026] Optional power setting model, including:

[0027]

[0028] Among them, P1 is the active power injected into the grid by the grid-forming new energy, k is the grid strength, U g1 is the grid voltage after the fault, δ is the power angle (the angle between the grid voltage and the PCC point voltage), α1 is the angle of grid voltage change after the fault, Q1 is the reactive power injected into the grid by the grid-forming renewable energy, and ρ is the resistance-inductance ratio.

[0029] In yet another aspect, the present invention further provides a computing device comprising: one or more processors;

[0030] a processor for executing one or more programs;

[0031] When the one or more programs are executed by the one or more processors, the above-described method is implemented.

[0032] In another aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed, the method described above is implemented.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention provides a method for power setting of a grid-type renewable energy source based on phasor geometry, comprising: obtaining parameters of the grid-type renewable energy source during steady-state operation and during a fault; constructing a phasor geometry model based on power flow based on the steady-state operation parameters and the fault parameters; establishing a phasor geometry diagram of the grid-type renewable energy source during a fault period based on the phasor geometry model; extracting phasor geometry relationships in the phasor geometry diagram; constructing a power setting model based on the geometric relationships; and setting the power of the grid-type renewable energy source during a fault period based on the power setting model. The present invention can effectively set the parameters of the grid-type renewable energy source after a fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a flow chart of the method of the present invention;

[0036] Figure 2 Schematic diagram of grid-connected new energy sources according to the method of the present invention;

[0037] Figure 3 A phasor diagram during a power grid fault of the method of the present invention;

[0038] Figure 4 is a phasor relationship diagram of the method of the present invention;

[0039] Figure 5 It is a structural diagram of the system of the present invention. DETAILED DESCRIPTION

[0040] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0041] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0042] Example 1:

[0043] This invention proposes a grid-type new energy power setting method based on phasor geometry, such as Figure 1 Shown, including:

[0044] Step 1: Obtain parameters of the grid-forming new energy system during steady-state operation and parameters during a fault, and construct a phasor geometry model based on power flow based on the parameters during steady-state operation and the parameters during a fault;

[0045] Step 2: Based on the phasor geometry model, a phasor geometry diagram of the grid-type new energy during the fault period is established, and the phasor geometry relationship in the phasor geometry diagram is extracted;

[0046] Step 3: Based on the geometric relationship, a power setting model is constructed, and based on the power setting model, the power during the grid-connected new energy fault is set.

[0047] Among them, the parameters of the grid-type new energy during steady-state operation include: PCC point voltage, PCC point voltage, grid-type converter output terminal voltage and line impedance;

[0048] The parameters of the grid-connected new energy failure include: the voltage drop at the PCC point, which is oriented towards the PCC point voltage.

[0049] Among them, the phasor geometric model is as follows:

[0050]

[0051] Among them, R s is the grid resistance, ρ is the resistance-to-inductance ratio, k is the grid strength, X s is the grid inductance.

[0052] The power setting model includes:

[0053]

[0054] Among them, P1 is the active power injected into the grid by the grid-forming new energy, k is the grid strength, U g1 is the grid voltage after the fault, δ is the power angle (the angle between the grid voltage and the PCC point voltage), α1 is the angle of grid voltage change after the fault, Q1 is the reactive power injected into the grid by the grid-forming renewable energy, and ρ is the resistance-inductance ratio.

[0055] The present invention will be further described below with reference to specific cases:

[0056] Specific cases mainly include:

[0057] Phase model construction based on power flow:

[0058] Schematic diagram of grid-connected new energy Figure 2 As shown, in steady-state operation, the PCC point voltage is oriented and the PCC point voltage is U g ∠0, the output voltage of the grid-type converter is U s ∠δ,Z s is the line impedance. Under grid fault conditions, the voltage at the PCC point drops to U′ g ∠α.

[0059] By derivation, the expressions of active and reactive power are:

[0060]

[0061] right The endpoints are decomposed into coordinates to The starting point is the origin, and the end point coordinates are (x u ,y u), transform the active power expression into:

[0062]

[0063] Formula (3) is the algebraic equation of a circle, so it satisfies the active power transmission conditions of the grid-connected system. The end track line (abbreviated as U s -P trajectory line) is is the center of the circle, A circle with a radius of .

[0064] Similarly, the reactive power expression (2) can be transformed into:

[0065]

[0066] with U s -P trajectory is similar, meeting the reactive power transmission conditions of the grid-connected system The end track line (abbreviated as U s -Q trajectory) is is the center of the circle, A circle with a radius of .

[0067] After considering the relationship between the grid-connected voltage of the grid-connected new energy and the power flow, the mathematical expression is simplified. The relationship between the grid-connected voltage of the grid-connected new energy and the active power can be simplified to a straight line, and the relationship between the grid-connected voltage of the grid-connected new energy and the reactive power is a circle. The specific expressions are shown in (5)(6) respectively.

[0068]

[0069] The resistance-inductance ratio ρ and the grid strength k are used to represent the resistive and inductive components of the grid impedance, as shown in formula (7).

[0070]

[0071] PCC point voltage U g As the reference voltage (x-axis), a rectangular coordinate system is established. The voltage at the outlet of the grid-type converter is U s , the phasor between the two voltage phasor endpoints is the transmission line impedance X g The product of the reactive power trajectory and the transmission current Is. The center of the reactive power trajectory circle is point O. As the voltage changes, the trajectory of the reactive power trajectory center changes along the AO ray. The radius of the reactive power trajectory circle can be calculated using Equation (6). The active power trajectory is a straight line parallel to the x-axis, and its height can be calculated using Equation (5).

[0072] The intersection of the active power trajectory and the reactive power trajectory is point C. The vector between intersection C and origin A is the port voltage of the grid-connected converter. The AB vector is the voltage at point PCC, and the BC vector is the product of the transmission line impedance and the grid-connected current.

[0073] The phasor diagram during power grid fault is as follows Figure 3 As shown in Figure 2. After a grid fault, the voltage at the PCC point drops slightly. The inertia of the active power synchronization link causes the power angle to increase, generating unbalanced power and, consequently, increasing system current. While the fault persists, the power synchronization link reduces active power and increases reactive power, restoring the power angle to a steady-state level.

[0074] Power setting strategy based on phasor geometry:

[0075] from Figure 3 Extract the phasor relationship, such as Figure 4 shown.

[0076] Under rated conditions, U g0 =1∠0°, the center of the reactive control circle O is (0.5, 0.5ρ), and the radius r0 is Active power control line y0=P0X g After a short circuit occurs in the power grid, the voltage drops to U g1 At the moment of the fault, the output voltage of the grid-type converter remains unchanged, but the phase angle is no longer maintained at δ. The grid-type converter enters the low voltage ride-through control phase, where the control goal is to maintain a constant grid output voltage.

[0077] After the voltage drops, the center of the reactive trajectory circle switches from point O to point O1, and the coordinates are (U g1 / 2,ρU g1 / 2), the converter output voltage meets the power angle stability condition under low voltage ride-through control. At this time, the output voltage of the grid-type converter is U s1 ∠(δ-α1), and Us1 is equal to Us0, then the terminal voltage can be further expressed as U s0 ∠(δ-α1)

[0078] The coordinates of point C1 are (U s1 cos(δ-α1),U s1 Substituting the value of Us1, we get the coordinates (cos(δ-α1), sin(δ-α1)). Draw a perpendicular line to AB through point C1, intersecting it at point E1. Draw a perpendicular line C1E1 through point O1, intersecting it at point D1.

[0079] From the geometric relationship, we can get:

[0080]

[0081] The length of O1C1 is the radius r1 of the reactive trajectory circle, which can be obtained from the geometric relationship:

[0082]

[0083] From equation (8) and equation (6), we can get the equation relationship:

[0084]

[0085] From formula (5) and the coordinates of point C1, we can get:

[0086]

[0087] Therefore, in order to achieve fault ride-through of grid-connected new energy, the power reference value that needs to be adjusted is:

[0088]

[0089] The present invention can be applied to grid-type new energy fault ride-through control to achieve precise regulation and control of active and reactive power in the event of a fault, thereby improving control accuracy and achieving better fault ride-through effects.

[0090] Example 2:

[0091] The present invention also proposes a grid-type new energy power setting system 200 based on phasor geometry, such as Figure 5 Shown, including:

[0092] The initialization unit 201 is used to obtain parameters of the grid-forming new energy during steady-state operation and parameters during fault conditions, and to construct a phasor geometric model based on power flow based on the parameters during steady-state operation and parameters during fault conditions;

[0093] A calculation unit 202 is configured to establish a phasor geometry diagram of the grid-type new energy during a fault period based on the phasor geometry model, and extract phasor geometric relationships in the phasor geometry diagram;

[0094] The setting unit 203 is used to build a power setting model based on the geometric relationship, and set the power during the grid-connected new energy fault based on the power setting model.

[0095] Among them, the parameters of the grid-type new energy during steady-state operation include: PCC point voltage, PCC point voltage, grid-type converter output terminal voltage and line impedance;

[0096] The parameters of the grid-connected new energy failure include: the voltage drop at the PCC point, which is oriented towards the PCC point voltage.

[0097] Among them, the phasor geometric model is as follows:

[0098]

[0099] Among them, R s is the grid resistance, ρ is the resistance-to-inductance ratio, k is the grid strength, Xs is the grid inductance.

[0100] The power setting model includes:

[0101]

[0102] Among them, P1 is the active power injected into the grid by the grid-forming new energy, k is the grid strength, U g1 is the grid voltage after the fault, δ is the power angle (the angle between the grid voltage and the PCC point voltage), α1 is the angle of grid voltage change after the fault, Q1 is the reactive power injected into the grid by the grid-forming renewable energy, and ρ is the resistance-inductance ratio.

[0103] The present invention can effectively adjust parameters of a grid-connected new energy source after a fault occurs.

[0104] Example 3:

[0105] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the method in the above embodiment.

[0106] Example 4:

[0107] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space that stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of the method in the above embodiment.

[0108] It will be understood by those skilled in the art that the 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. Furthermore, 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. The solutions in the embodiments of the present invention may be implemented in various computer languages, for example, the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0109] 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 flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, 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 flowcharts and / or block diagrams. 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.

[0110] 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.

[0111] 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 The steps for the function specified in one or more boxes.

[0112] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0113] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A grid-type renewable energy power setting method based on phasor geometry, characterized in that: include: Obtaining parameters of the grid-forming new energy during steady-state operation and parameters during a fault, and constructing a phasor geometric model based on power flow based on the parameters during steady-state operation and the parameters during a fault; Based on the phasor geometry model, a phasor geometry diagram of the grid-type new energy during a fault period is established, and a phasor geometry relationship in the phasor geometry diagram is extracted; Based on the geometric relationship, a power setting model is constructed, and based on the power setting model, the power during the grid-connected new energy fault is set.

2. The grid-connected new energy power setting method according to claim 1, characterized in that: The parameters of the grid-type new energy during steady-state operation include: PCC point voltage, PCC point voltage, grid-type converter output terminal voltage and line impedance; The parameters of the grid-connected new energy failure include: the voltage drop at the PCC point, which is oriented towards the PCC point voltage.

3. The grid-connected new energy power setting method according to claim 1, characterized in that: The phasor geometric model is as follows: Among them, R s is the grid resistance, ρ is the resistance-to-inductance ratio, k is the grid strength, X s is the grid inductance.

4. The grid-connected new energy power setting method according to claim 1, characterized in that: The power setting model includes: Among them, P1 is the active power injected into the grid by the grid-forming new energy, k is the grid strength, U g1 is the grid voltage after the fault, δ is the power angle, α1 is the angle of grid voltage change after the fault, Q1 is the reactive power injected into the grid by the grid-forming renewable energy, and ρ is the resistance-inductance ratio.

5. A grid-type new energy power setting system based on phasor geometry, characterized in that: include: An initialization unit is used to obtain parameters of the grid-forming new energy during steady-state operation and parameters during fault conditions, and to construct a phasor geometric model based on power flow based on the parameters during steady-state operation and the parameters during fault conditions; a calculation unit, configured to establish a phasor geometry diagram of the grid-forming new energy during a fault period based on the phasor geometry model, and extract a phasor geometry relationship in the phasor geometry diagram; The setting unit is used to construct a power setting model based on the geometric relationship, and to set the power during the grid-connected new energy fault based on the power setting model.

6. The grid-connected new energy power setting system according to claim 5, characterized in that: The parameters of the grid-type new energy during steady-state operation include: PCC point voltage, PCC point voltage, grid-type converter output terminal voltage and line impedance; The parameters of the grid-connected new energy failure include: the voltage drop at the PCC point, which is oriented towards the PCC point voltage.

7. The grid-connected new energy power setting system according to claim 5, characterized in that: The phasor geometric model is as follows: Among them, R s is the grid resistance, ρ is the resistance-to-inductance ratio, k is the grid strength, X s is the grid inductance.

8. The grid-connected new energy power setting system according to claim 5, characterized in that: The power setting model includes: Among them, P1 is the active power injected into the grid by the grid-forming new energy, k is the grid strength, U g1 is the grid voltage after the fault, δ is the power angle, α1 is the angle of grid voltage change after the fault, Q1 is the reactive power injected into the grid by the grid-forming renewable energy, and ρ is the resistance-inductance ratio.

9. A computer device, characterized in that: include: one or more processors; a processor for executing one or more programs; When the one or more programs are executed by the one or more processors, the method according to any one of claims 1 to 4 is implemented.

10. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the computer program is executed, the method according to any one of claims 1 to 4 is implemented.

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