Transient synchronization performance-based current limiting strategy generation method and system for network construction type equipment

Abstract

The invention discloses a transient synchronization performance-based current limiting strategy generation method and system for network construction type equipment, and belongs to the technical field of network construction type converter analysis and design. Comprising the following steps: considering a current amplitude limiting effect during a fault period, and constructing a transient synchronous model of a grid-connected system of the network construction type equipment; based on the transient synchronization model, determining the approximate estimation of the stability domain boundary of the grid-connected system of the network construction type equipment at an unstable equilibrium point through one-time linear estimation; based on the stability domain boundary approximate estimation, determining a limit clearing angle and limit clearing time when the network construction type equipment fails in combination with a fault trajectory of a grid-connected system of the network construction type equipment; and determining a current limiting strategy based on the limit cut-off angle and the limit cut-off time. The method can accurately guide the adjustment of the current amplitude limiting value of the network construction type equipment, improves the transient synchronization stability of the network construction type equipment, and solves a problem that there is no accurate current limiting quantitative adjustment strategy in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of grid-type converter analysis and design, and in particular to a method and system for generating a grid-type device current limiting strategy based on transient synchronization performance. Background Art

[0002] The statements in this section merely mention background art related to the present invention and do not necessarily constitute prior art.

[0003] It is extremely important to ensure the reliable consumption of large-scale new energy and the safe and stable operation of the power grid. At present, most of the operating new energy power generation systems adopt the grid-following control strategy, that is, they follow the grid based on the phase locked loop (PLL). They must rely on a strong AC grid to work properly and do not have the ability to actively support voltage and frequency. Large-scale access is prone to cause a series of instability problems. Different from traditional grid-following technology, the grid-building equipment can achieve self-synchronization and actively build voltage and frequency. By simulating the rotor characteristics of synchronous generators, it provides virtual inertia and damping for the system, improves the safe and stable operation margin of the power grid, and has become a frontier and hot spot of research.

[0004] However, unlike the higher overcurrent withstand voltage level of synchronous machines, the short-circuit current level of power electronic devices in grid-type equipment is lower. After overcurrent, current limiting or switching to grid-following control will be triggered. The dynamic response of the system is highly nonlinear, and the current limiting value has a great impact on its dynamic response. Existing relevant studies have shown that converters are more likely to cause power angle instability under current limiting conditions. The lower the current limiting, the more serious the power angle instability problem. However, the corresponding current limiting control is based on experience and intuitive judgment, and lacks precise quantitative adjustment strategies. Summary of the invention

[0005] In order to address the deficiencies in the prior art, the present invention provides a method, system, electronic device, computer storage medium and computer program product for generating a current limiting strategy for a networking type device based on transient synchronization performance, which analyzes and calculates the quantitative relationship between the networking type transient synchronization stability margin and the current limiting value, and guides the design and setting of the current limiting value for the networking type device.

[0006] In a first aspect, the present invention provides a method for generating a current limiting strategy for a networking device based on transient synchronization performance;

[0007] A method for generating a current limiting strategy for a networking device based on transient synchronization performance, comprising:

[0008] Considering the current limiting effect during faults, a transient synchronization model of the grid-connected system of grid-connected equipment is constructed;

[0009] Based on the transient synchronization model, an approximate estimate of the stability region boundary of the grid-connected system of the grid-connected equipment is determined by a linear estimation at an unstable equilibrium point;

[0010] Based on the approximate estimation of the boundary of the stability region and in combination with the fault trajectory of the grid-connected system of the grid-connected equipment, the limit resection angle and the limit resection time of the grid-connected equipment when the grid-connected equipment fails are determined; based on the limit resection angle and the limit resection time, the current limiting strategy is determined.

[0011] In some embodiments, the consideration of the current limiting effect during a fault and the construction of a transient synchronization model of a grid-connected system of a grid-connected device are specifically as follows: considering the change in the electromagnetic power output by the grid-connected device when the current limiting effect during a fault occurs, the output angle, output frequency, inertia control parameters, mechanical power reference value, current limiting value, grid-connected system voltage amplitude and damping control parameters of the grid-connected device are combined to establish a transient synchronization model of a grid-connected system of a grid-connected device.

[0012] In some embodiments, the slope of a linear estimate is expressed as:

[0013]

[0014] In the formula, D represents the damping control parameter of the network-building device, J represents the inertia control parameter of the network-building device, and I max Indicates the current limit value of the network-building equipment, U g0 Indicates the voltage amplitude of the grid-connected system.

[0015] In some embodiments, the limiting resection angle is expressed as:

[0016]

[0017] In the formula, δ max represents the limit resection angle, δ0 represents the stable equilibrium point of the network-type equipment before the fault, a represents the intermediate coefficient, K represents the slope of the linear estimation, δ u Indicates the unstable equilibrium point of the meshing device.

[0018] In some embodiments, the limiting resection angle is expressed as:

[0019]

[0020] In the formula, δ max represents the limit resection angle, δ0 represents the stable equilibrium point of the network-type equipment before the fault, a represents the intermediate coefficient, K represents the slope of the linear estimation, δ u Indicates the unstable equilibrium point of the meshing device.

[0021] In some embodiments, the current limiting strategy is determined based on the limit cut-off angle and the limit cut-off time as follows: based on the relationship between the limit cut-off angle and the limit cut-off time and the slope of the approximate estimate of the stability domain boundary, the current limiting value is adjusted to increase the limit cut-off angle and the limit cut-off time.

[0022] In a second aspect, the present invention provides a network-type device current limiting strategy generation system based on transient synchronization performance;

[0023] A network-building device current limiting strategy generation system based on transient synchronization performance, comprising:

[0024] The model building module is configured to: consider the current limiting effect during the fault period and build a transient synchronization model of the grid-connected system of the grid-connected equipment;

[0025] A stability domain boundary estimation module is configured to: determine an approximate estimate of a stability domain boundary of a grid-connected system of a grid-connected device through a linear estimation at an unstable equilibrium point based on the transient synchronization model;

[0026] The current limiting strategy generation module is configured to: determine the limit cut-off angle and limit cut-off time of the grid-connected device when the grid-connected device fails based on the approximate estimation of the stability domain boundary and the fault trajectory of the grid-connected device grid-connected system; determine the current limiting strategy based on the limit cut-off angle and limit cut-off time.

[0027] In a third aspect, the present invention provides an electronic device;

[0028] An electronic device comprises a memory, a processor and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method for generating a current limiting strategy for a networking device based on transient synchronization performance.

[0029] In a fourth aspect, the present invention provides a computer-readable storage medium;

[0030] A computer-readable storage medium stores a computer program / instruction thereon, which, when executed by a processor, implements the steps of the method for generating a current limiting strategy for a networking device based on transient synchronization performance.

[0031] In a fifth aspect, the present invention provides a computer program product;

[0032] A computer program product includes a computer program / instruction, which, when executed by a processor, implements the steps of the above-mentioned method for generating a current limiting strategy for a networking device based on transient synchronization performance. Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. The technical solution provided by the present invention is based on the estimation of the boundary of the stability domain and the analytical calculation of the fault limit removal angle / time, and quantitatively analyzes the relationship between the current limiting value of the network-building equipment and the transient synchronization stability performance, taking into account the current limiting effect and the damping effect, and the estimation of the fault limit and stability margin is more accurate, which can accurately guide the adjustment of the current limiting value and improve the transient synchronization stability of the system.

[0034] 2. The technical solution provided by the present invention takes into account the current limiting value of the grid-connected equipment when constructing the transient synchronization model of the grid-connected system of the grid-connected equipment, which is closer to practical applications and reduces the error with the actual situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings in the specification, which constitute a part of the present invention, 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 improper limitations on the present invention.

[0036] Figure 1 A schematic flow chart of a method for generating a current limiting strategy for a networking device based on transient synchronization performance provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "include" and "have" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising 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.

[0039] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0040] Embodiment 1

[0041] The existing quantitative evaluation based on transient synchronization performance cannot determine the effect of the current limiting strategy on the transient synchronization of the grid-type equipment, and cannot provide a specific adjustment method for the current limiting value to enhance the stability of transient synchronization, and cannot quantitatively analyze the impact of the current limiting strategy on the transient synchronization of the grid-type equipment; therefore, in order to accurately provide the current limiting value of the grid-type converter under the action of current limiting, and to facilitate engineers to understand and apply in on-site engineering, the present invention provides a method for generating a current limiting strategy for grid-type equipment based on transient synchronization performance.

[0042] Next, combine Figure 1 A method for generating a current limiting strategy for a networking device based on transient synchronization performance disclosed in this embodiment is described in detail. The method for generating a current limiting strategy for a networking device based on transient synchronization performance comprises the following steps:

[0043] S1. Considering the current limiting effect during faults, a transient synchronization model of the grid-connected system of grid-connected equipment is constructed.

[0044] Specifically, considering the change of electromagnetic power output by the grid-forming equipment when the current limiting function is applied during the fault period, the transient synchronization model of the grid-forming equipment is established by combining the output angle, output frequency, inertia control parameters, mechanical power reference value, current limiting value, grid-connected system voltage amplitude and damping control parameters of the grid-forming equipment. The transient synchronization model is expressed as:

[0045]

[0046] In the formula, δ represents the output angle of the networking device, ω represents the output frequency of the networking device, represents the derivative of the output angle with respect to time, represents the derivative of the output frequency with respect to time, J represents the inertia control parameter of the network-type device, and P m Indicates the mechanical power reference value of the network-building equipment, I max Indicates the current limit value of the network-building equipment, U g0 represents the grid-connected system voltage amplitude of the grid-connected equipment, and D represents the damping control parameter of the grid-connected equipment.

[0047] In this embodiment, when constructing the transient synchronization model of the grid-connected system of the grid-connected equipment, the current limit value of the grid-connected equipment is taken into consideration, which is closer to the actual application and reduces the error with the actual situation.

[0048] Furthermore, in order to facilitate subsequent calculations, in this embodiment, coordinate transformation is performed on the transient synchronization model to move the unstable equilibrium point of the transient synchronization model to the origin.

[0049] Specifically, let y = δ - δ u ,but Transformed into:

[0050]

[0051] In the formula, δ u Indicates the unstable equilibrium point of the meshing device.

[0052] S2. Based on the transient synchronization model, the stable domain boundary of the networking device is approximated by a linear estimation at the unstable equilibrium point, which is used as an approximate estimate of the stable domain boundary.

[0053] Specifically, the slope of a linear estimate is expressed as:

[0054]

[0055] In the formula, D represents the damping control parameter of the network-building device, J represents the inertia control parameter of the network-building device, and I max Indicates the current limit value of the network-building equipment, U g0 Indicates the voltage amplitude of the grid-connected system.

[0056] Based on this, it can be known that the slope K of a linear estimation is related to the current limit value I max Directly proportional.

[0057] Furthermore, the approximate estimate of the stability region boundary of the grid-connected system of grid-connected devices is expressed as:

[0058] ω=K(δ-δ u ).

[0059] S3. Based on the approximate estimation of the boundary of the stable region and combined with the fault trajectory of the networking type equipment, the limit resection angle and limit resection time of the networking type equipment when it fails are determined.

[0060] Specifically, when a three-phase short circuit or a grid voltage drop to zero occurs in a network-forming device, the system trajectory in the phase plane is δ = J / (2P m ω 2 )+δ0, combined with the approximate estimate of the stability region boundary ω=K(δ-δ u ), combining the above two formulas, we can get the limit cut-off angle of the system under the most serious fault, which is expressed as:

[0061]

[0062] In the formula, δ max represents the limit resection angle, δ0 represents the stable equilibrium point of the network-type equipment before the fault, a represents the intermediate coefficient, a=J / P m , K represents the slope of a linear estimate, δ u Indicates the unstable equilibrium point of the meshing device.

[0063] Furthermore, the limit removal time is expressed as:

[0064]

[0065] In the formula, a represents the intermediate coefficient, K represents the slope of the linear estimate, and δ u It represents the unstable equilibrium point of the networking device, and δ0 represents the stable equilibrium point of the networking device before the failure.

[0066] S4. Determine a current limiting strategy based on a limit cut-off angle and a limit cut-off time.

[0067] Specifically, based on the calculation formula of the limit resection angle, it can be clearly seen that δ max There is a quadratic function relationship between δ and K, then max The condition for taking the minimum point is:

[0068] aK 2 =1 / (δ0-1).

[0069] Here, the calculation formula of the limit resection angle is simplified to the following formula:

[0070]

[0071] Based on this, δ max There is a quadratic function relationship between As an independent variable x), the minimum value is taken at x = -b / 2a, and we get

[0072] If aK 2 >1 / (δ0-1),δ max with I max In this case, increasing the current limit value can increase the limit cut-off angle / time and improve the transient synchronization stability of the system.

[0073] If aK 2 <1 / (δ0-1), δ max with I max Inversely proportional to the current limit, increasing the current limit value will reduce the limit cut-off angle / time, thereby worsening the transient synchronization stability of the system; at this time, reduce the current limit value.

[0074] Furthermore, δ max with I max The quantitative relationship between them is expressed as:

[0075]

[0076] Based on this, the relationship between the current limit value and the limit cut-off angle is quantified, which can predict the change of the corresponding limit cut-off angle after the current limiting strategy is executed and improve the transient synchronization stability of the system.

[0077] Embodiment 2

[0078] This embodiment discloses a system for generating a current limiting strategy for a networking device based on transient synchronization performance, including:

[0079] The model building module is configured to: consider the current limiting effect during the fault period and build a transient synchronization model of the network-forming device;

[0080] A stable domain boundary estimation module is configured to: determine an approximate estimate of a stable domain boundary of a meshing device by a linear estimation at an unstable equilibrium point based on the transient synchronization model;

[0081] The current limiting strategy generation module is configured to: determine the limit resection angle and limit resection time of the networking type device when the networking type device fails based on the approximate estimation of the stability domain boundary and the fault trajectory of the networking type device; determine the current limiting strategy based on the limit resection angle and limit resection time.

[0082] It should be noted here that the above-mentioned model building module, stable domain boundary estimation module and current limiting strategy generation module correspond to the steps in Embodiment 1, and the above-mentioned modules and the corresponding steps implement the same examples and application scenarios, but are not limited to the contents disclosed in Embodiment 1. It should be noted that the above-mentioned modules, as part of the system, can be executed in a computer system such as a set of computer executable instructions.

[0083] Embodiment 3

[0084] Embodiment 3 of the present invention provides an electronic device, including a memory and a processor, and computer instructions stored in the memory and running on the processor. When the computer instructions are executed by the processor, the steps of the method for generating a current limiting strategy for a networking device based on transient synchronization performance are completed.

[0085] Embodiment 4

[0086] Embodiment 4 of the present invention provides a computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, the steps of the method for generating a current limiting strategy for a networking device based on transient synchronization performance are completed.

[0087] Embodiment 5

[0088] Embodiment 5 of the present invention provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the method for generating a current limiting strategy for a networking device based on transient synchronization performance.

[0089] 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.

[0090] 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.

[0091] These computer program instructions can also be loaded onto a computer or other programmable data processing device, and a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide 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.

[0092] The description of each embodiment in the above embodiments has different emphases. For parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for generating a current limiting strategy for networking devices based on transient synchronization performance, characterized in that: include: Considering the current limiting effect during faults, a transient synchronization model of the grid-connected system of grid-connected equipment is constructed; Based on the transient synchronization model, an approximate estimate of the stability region boundary of the grid-connected system of the grid-connected equipment is determined by a linear estimation at an unstable equilibrium point; Based on the approximate estimation of the boundary of the stability region and in combination with the fault trajectory of the grid-connected system of the grid-connected equipment, the limit cut-off angle and the limit cut-off time of the grid-connected equipment when the grid-connected equipment fails are determined; based on the limit cut-off angle and the limit cut-off time, the current limiting strategy is determined.

2. The method for generating a current limiting strategy for a networking device based on transient synchronization performance according to claim 1, characterized in that: The method of considering the current limiting effect during a fault and constructing a transient synchronization model of the grid-connected system of the grid-connected equipment is specifically as follows: considering the change in the electromagnetic power output by the grid-connected equipment when the current limiting effect during a fault occurs, combining the output angle, output frequency, inertia control parameters, mechanical power reference value, current limiting value, grid-connected system voltage amplitude and damping control parameters of the grid-connected equipment, to establish a transient synchronization model of the grid-connected system of the grid-connected equipment.

3. The method for generating a current limiting strategy for a networking device based on transient synchronization performance according to claim 1, characterized in that: The slope of a linear estimate is expressed as: In the formula, D represents the damping control parameter of the network-building device, J represents the inertia control parameter of the network-building device, and I max Indicates the current limit value of the network-building equipment, U g0 Indicates the voltage amplitude of the grid-connected system.

4. The method for generating a current limiting strategy for a networking device based on transient synchronization performance according to claim 1, characterized in that: The limiting resection angle is expressed as: In the formula, δ max represents the limit resection angle, δ0 represents the stable equilibrium point of the network-type equipment before the fault, a represents the intermediate coefficient, K represents the slope of the linear estimation, δ u Indicates the unstable equilibrium point of the meshing device.

5. The method for generating a current limiting strategy for a networking device based on transient synchronization performance according to claim 1, characterized in that: The limit removal time is expressed as: In the formula, a represents the intermediate coefficient, K represents the slope of the linear estimate, and δ u It represents the unstable equilibrium point of the networking device, and δ0 represents the stable equilibrium point of the networking device before the failure.

6. The method for generating a current limiting strategy for networking devices based on transient synchronization performance according to claim 1, characterized in that: The current limiting strategy is determined based on the limit cut-off angle and the limit cut-off time. Specifically, the current limiting value is adjusted based on the relationship between the limit cut-off angle and the limit cut-off time and the slope of the approximate estimation of the stability domain boundary to increase the limit cut-off angle and the limit cut-off time.

7. A network-type device current limiting strategy generation system based on transient synchronization performance, characterized in that: include: The model building module is configured to: consider the current limiting effect during the fault period and build a transient synchronization model of the grid-connected system of the grid-connected equipment; A stability domain boundary estimation module is configured to: determine an approximate estimate of a stability domain boundary of a grid-connected system of a grid-connected device through a linear estimation at an unstable equilibrium point based on the transient synchronization model; The current limiting strategy generation module is configured to: determine the limit resection angle and limit resection time of the networking type device when the networking type device fails based on the approximate estimation of the stability domain boundary and the fault trajectory of the networking type device; determine the current limiting strategy based on the limit resection angle and limit resection time.

8. An electronic device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method for generating a current limiting strategy for a networking device based on transient synchronization performance as described in any one of claims 1-6.

9. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instruction is executed by a processor, the steps of the method for generating a current limiting strategy for a networking device based on transient synchronization performance as described in any one of claims 1 to 6 are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instruction is executed by a processor, the steps of the method for generating a current limiting strategy for a networking device based on transient synchronization performance as described in any one of claims 1 to 6 are implemented.

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