System strength evaluation method and device of power system, electronic equipment and medium

Abstract

This invention discloses a method, apparatus, electronic device, and medium for assessing the system strength of a power system, addressing the problems of high computational complexity, large errors, and limited application in large-scale real-world power grids in current related technologies. The power system comprises multiple grid-connected devices; each grid-connected device corresponds to one network-building device. The invention obtains the power system grid admittance matrix, the operating output and critical short-circuit ratio of each grid-connected device under current operating conditions, and the equivalent impedance of each network-building device. A matrix transformation based on node admittance correction is performed using the grid admittance matrix and each equivalent impedance to obtain the grid admittance matrix. The generalized operating short-circuit ratio is calculated based on the grid admittance matrix and each operating output. A generalized operating short-circuit ratio threshold is calculated based on each critical short-circuit ratio, considering the participation factors of multiple grid-connected devices on the generalized operating short-circuit ratio. The system strength is assessed based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

Description

Technical Field

[0001] This invention relates to the field of power system stability analysis technology, and in particular to a method, apparatus, electronic device and medium for assessing the system strength of a power system. Background Technology

[0002] Currently, the traditional power system, primarily reliant on fossil fuel consumption, is transforming into a new type of power system dominated by renewable energy sources. High proportions of renewable energy and power electronic equipment are its main characteristics. These renewable energy power electronic devices widely employ grid-connected control technology, offering flexible power regulation capabilities. However, compared to conventional synchronous generator units, they exhibit weaker disturbance rejection and support. As conventional synchronous generator units in renewable energy power systems are gradually replaced by power electronic equipment, the system's ability to resist voltage shifts or instability after disturbances (i.e., system voltage support strength, hereinafter referred to as "system strength") significantly decreases, seriously threatening the safe and stable operation of renewable energy power systems.

[0003] Therefore, exploring the use of grid-based control technology in power electronic equipment to provide active voltage support capability is a current focus of attention. However, the interactions between various types of power electronic equipment and between them and the power grid are complex, and the impact of equipment operation control characteristics on system voltage dynamic performance is unclear, making accurate assessment of system strength difficult. The risk of power system instability caused by inaccurate system strength assessment is increasing daily, posing a severe challenge to ensuring the safe and stable operation of new energy power systems. Currently, the short-circuit ratio of multiple new energy power plants or the generalized short-circuit ratio method is mainly used for strength assessment of new energy power systems containing grid-based power electronic equipment.

[0004] When using the short-circuit ratio method for multiple power plants in new energy sources to assess system strength, the cross-scale voltage support effect of grid-connected power electronic equipment cannot be considered, leading to significant calculation errors. Furthermore, its system strength threshold relies heavily on trial and error through numerous electromagnetic transient simulations, and the artificially introduced conservatism results in low economic efficiency. In addition, while this method is based on steady-state circuit equivalents and is computationally simple, it lacks a rigorous mathematical foundation and has a weak correlation with the stability of actual systems.

[0005] While the generalized short-circuit ratio method can accurately reflect the system stability boundary, it relies on broadband impedance measurement technology, resulting in high computational complexity. This makes it particularly difficult to apply efficiently when grid operation modes change frequently. Although it can demonstrate the dynamic support role of grid-connected equipment, its application in large-scale practical power grids is limited. Summary of the Invention

[0006] This invention provides a system strength assessment method, apparatus, electronic device, and medium for power systems, which solves or partially solves the technical problems of high computational complexity, large errors, and limited application in large-scale practical power grids in current related technologies.

[0007] This invention provides a method for assessing the system strength of a power system, wherein the power system comprises multiple grid-connected devices; each grid-connected device corresponds to one grid-building device; the method includes:

[0008] Obtain the grid admittance matrix of the power system, the operating output and critical short-circuit ratio of each of the grid-connected devices under the current operating conditions, and the equivalent impedance of each of the grid-connected devices;

[0009] The grid admittance matrix is ​​obtained by performing a matrix transformation based on node admittance correction using the grid admittance matrix and each of the equivalent impedances.

[0010] Based on the network admittance matrix and each of the operating outputs, the generalized operating short-circuit ratio is calculated.

[0011] Based on each of the aforementioned critical short-circuit ratios, and taking into account the participation factors of the multiple network-connected devices on the generalized operating short-circuit ratio, the generalized operating short-circuit ratio threshold is calculated.

[0012] The system strength of the power system is assessed based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

[0013] Optionally, the calculation process for the critical short-circuit ratio of each of the aforementioned network devices includes:

[0014] Construct an electromagnetic transient simulation model of the single-machine infinite bus system of the network-connected device;

[0015] The equivalent impedance of the grid-connected equipment is determined by adjusting the equivalent impedance of the single-machine infinite bus system based on the judgment of single-machine oscillation instability.

[0016] Different operating conditions are set based on the active power step change adjustment mechanism, and the critical short-circuit ratio of the grid-connected equipment under each operating condition is determined according to the equivalent impedance of the power grid.

[0017] Optionally, each of the network-type devices is installed at the grid-connected bus of the corresponding network-type device's single-unit infinite bus system; the calculation process for the equivalent impedance of each of the network-type devices includes:

[0018] For each of the operating conditions, the terminal voltage of the grid-connected equipment is kept constant. The grid-connected critical short-circuit ratio of the infinite system is determined by adjusting the equivalent impedance of the infinite system after grid connection based on the joint grid-connected oscillation instability judgment.

[0019] Based on the critical short-circuit ratio and the grid-connected critical short-circuit ratio, the combined equivalent impedance of the grid-type equipment under the operating conditions is calculated.

[0020] The average value is calculated based on the combined equivalent impedance under each of the aforementioned operating conditions to determine the equivalent impedance of the network-type equipment applicable to each of the aforementioned operating conditions.

[0021] Optionally, the step of performing a matrix transformation based on nodal admittance correction using the grid admittance matrix and each of the equivalent impedances to obtain the grid admittance matrix includes:

[0022] The set of nodes to which the grid-type equipment is connected is selected from the grid admittance matrix; each node in the set corresponds to one grid-type equipment.

[0023] Based on each of the equivalent impedances, the admittance of each node where the grid-type equipment is located in the grid admittance matrix is ​​corrected one by one to obtain a grid corrected admittance matrix that includes the equivalent impedance of the grid-type equipment.

[0024] The power grid correction admittance matrix is ​​divided into several sub-matrices according to the grid-connected bus and passive bus of the grid-type equipment.

[0025] Based on the aforementioned sub-matrices, a network admittance matrix that retains the network bus of the network-connected equipment is constructed through matrix transformation.

[0026] Optionally, the step of calculating the generalized operating short-circuit ratio based on the network admittance matrix and each of the operating outputs includes:

[0027] Based on the respective operating outputs, construct the grid-connected output matrix of the power system;

[0028] Based on the net admittance matrix and the net output matrix, an extended admittance matrix is ​​constructed.

[0029] The minimum eigenvalue of the extended admittance matrix is ​​solved, and the obtained minimum eigenvalue is used as the generalized operating short-circuit ratio when considering the supporting role of grid-type equipment in the power system.

[0030] Optionally, the step of calculating the generalized operating short-circuit ratio threshold based on each of the critical short-circuit ratios, while simultaneously considering the participation factors of the multiple network-connected devices on the generalized operating short-circuit ratio, includes:

[0031] Based on the extended admittance matrix and the generalized operating short-circuit ratio, determine the normalized left and right eigenvectors of the extended admittance matrix corresponding to the generalized operating short-circuit ratio;

[0032] Based on the left feature vector and the right feature vector, the participation factor of each of the network-connected devices in the generalized operating short-circuit ratio is determined;

[0033] The generalized operating short-circuit ratio threshold of the power system is obtained by weighted summation of the critical short-circuit ratio of each grid-connected device and the corresponding participation factor.

[0034] Optionally, the method further includes:

[0035] The stability margin of the power system is calculated based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

[0036] When the stability margin is less than or equal to a preset stability margin threshold, an early warning signal is generated;

[0037] Based on the equivalent impedance of each of the network-type devices, the devices are sorted in ascending order of equivalent impedance value to obtain a sequence table of network-type devices with high to low priority for deployment.

[0038] Based on the participation factor of each of the network-connected devices for the generalized operating short-circuit ratio, the devices are sorted in descending order of participation factor value to obtain a power reduction order table of network-connected devices from high to low priority in reducing power output.

[0039] The warning signal, the commissioning sequence table, and the output reduction sequence table are pushed to the system display interface so that maintenance personnel can make decisions based on the commissioning sequence table and the output reduction sequence table to commission network-type equipment according to the corresponding priority, and / or reduce the operating output of network-type equipment.

[0040] The present invention also provides a system strength assessment device for a power system, wherein the power system includes multiple grid-connected devices; each grid-connected device corresponds to one grid-building device; the device includes:

[0041] The data acquisition unit is used to acquire the grid admittance matrix of the power system, the operating output and critical short-circuit ratio of each of the grid-connected devices under the current operating conditions, and the equivalent impedance of each of the grid-connected devices.

[0042] The matrix transformation unit is used to perform a matrix transformation based on node admittance correction according to the grid admittance matrix and each of the equivalent impedances to obtain the grid admittance matrix.

[0043] The generalized operating short-circuit ratio calculation unit is used to calculate the generalized operating short-circuit ratio based on the network admittance matrix and each of the operating outputs;

[0044] The generalized operating short-circuit ratio threshold calculation unit is used to calculate the generalized operating short-circuit ratio threshold based on each of the critical short-circuit ratios, while also considering the participation factors of the multiple network-connected devices on the generalized operating short-circuit ratio.

[0045] The system strength assessment unit is used to assess the system strength of the power system based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

[0046] The present invention also provides an electronic device, the device comprising a processor and a memory:

[0047] The memory is used to store program code and transmit the program code to the processor;

[0048] The processor is used to execute the system strength assessment method for the power system as described above, according to the instructions in the program code.

[0049] The present invention also provides a computer-readable storage medium for storing program code for performing the system strength assessment method for a power system as described in any of the preceding claims.

[0050] As can be seen from the above technical solutions, the present invention has the following advantages:

[0051] A method for assessing the system strength of a power system is provided. The power system comprises multiple grid-connected devices; each grid-connected device corresponds to one grid-connected device. For the system assessment process, firstly, the grid admittance matrix of the power system, the operating output and critical short-circuit ratio of each grid-connected device under the current operating conditions, and the equivalent impedance of each grid-connected device are obtained as the basis for subsequent calculations. The grid admittance matrix of the power system is based on large-scale electromechanical transient simulation, while the relevant data for grid-connected and grid-connected devices are obtained through small-scale electromagnetic transient simulation. Thus, by employing a hybrid approach of large-scale electromechanical transient simulation and small-scale electromagnetic transient simulation, the strength of a new energy power system containing grid-connected devices can be rapidly assessed. This method eliminates the need for repeated trial-and-error of strength thresholds using large-scale full electromagnetic transient simulation and the use of broadband impedance measurements, thereby reducing the required computational resources and complexity. Next, a matrix transformation based on nodal admittance correction is performed using the grid admittance matrix and each equivalent impedance to obtain the grid-connected admittance matrix. This allows the voltage support effect of grid-connected equipment on multiple operating conditions of the system to be considered in subsequent index calculations. Then, based on the grid-connected admittance matrix and each operating output, the generalized operating short-circuit ratio is calculated. This comprehensively considers the operating output of grid-connected equipment, taking into account the voltage support effect of grid-connected equipment on multiple operating conditions of the system. The generalized operating short-circuit ratio is calculated and used as an index for evaluating the strength of new energy power systems containing grid-connected equipment, making this index closely related to power system stability. Next, based on each critical short-circuit ratio and considering the participation factors of multiple grid-connected equipment on the generalized operating short-circuit ratio, the generalized operating short-circuit ratio threshold is calculated. Finally, the system strength of the power system is evaluated based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold. By comprehensively considering the critical short-circuit ratio of grid-connected equipment in the power system and the actual participation factors of each grid-connected equipment in supporting system strength, the generalized operating short-circuit ratio threshold, which serves as the system stability boundary, can be accurately calculated, enabling the system strength assessment results to accurately reflect the stability of new energy power systems containing grid-connected equipment. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A flowchart illustrating the steps of a system strength assessment method for a power system;

[0054] Figure 2 A schematic diagram of the topology for the electromagnetic transient simulation model of a single-machine infinite bus system for network-type equipment;

[0055] Figure 3 This is a block diagram illustrating the implementation principle of the rapid strength assessment method for new energy power systems based on hybrid drive of electromechanical transient and electromagnetic transient simulation proposed in this embodiment of the invention.

[0056] Figure 4 A schematic diagram of the overall process of a system strength assessment method for a power system;

[0057] Figure 5 This is a structural block diagram of a system strength assessment device for a power system. Detailed Implementation

[0058] This invention provides a system strength assessment method, apparatus, electronic device, and medium for power systems, which solves or partially solves the technical problems of high computational complexity, large errors, and limited application in large-scale practical power grids in current related technologies.

[0059] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0060] To enable those skilled in the art to better understand the technical solutions provided in the embodiments of the present invention, some of the technical features involved in the solutions are briefly described first:

[0061] Grid-forming devices, also known as grid-connected power electronic equipment, refer to devices in a power system that can actively maintain grid voltage and frequency stability and possess grid support capabilities. Grid-forming devices include grid-connected energy storage, grid-connected reactive power compensation, static synchronous condensers, grid-connected photovoltaic systems, and grid-connected wind turbines. These devices typically possess strong inertia and damping characteristics; their grid connection helps improve system strength and provides necessary voltage and frequency regulation functions within the grid.

[0062] Grid-following devices, also known as grid-connected power electronic devices, are those that rely on the grid voltage and frequency to operate and do not possess the ability to actively maintain grid stability. Grid-following devices include grid-connected renewable energy sources and grid-connected energy storage. When these devices are connected to the grid, they consume system power and typically passively adapt to grid conditions, following changes in grid voltage and frequency.

[0063] As an example, the complex interactions between various types of power electronic equipment and between them and the power grid, coupled with the unclear impact of equipment operation and control characteristics on system voltage dynamics, make accurate assessment of system strength difficult. The risk of power system instability due to inaccurate system strength assessments is increasing daily, posing a severe challenge to ensuring the safe and stable operation of new energy power systems. Currently, the short-circuit ratio of multiple new energy power plants or the generalized short-circuit ratio method is mainly used for strength assessment of new energy power systems containing grid-type power electronic equipment.

[0064] When using the short-circuit ratio method for multiple power plants in new energy sources to assess system strength, the cross-scale voltage support effect of grid-connected power electronic equipment cannot be considered, leading to significant calculation errors. Furthermore, its system strength threshold relies heavily on trial and error through numerous electromagnetic transient simulations, and the artificially introduced conservatism results in low economic efficiency. In addition, while this method is based on steady-state circuit equivalents and is computationally simple, it lacks a rigorous mathematical foundation and has a weak correlation with the stability of actual systems.

[0065] While the generalized short-circuit ratio method can accurately reflect the system stability boundary, it relies on broadband impedance measurement technology, resulting in high computational complexity. This makes it particularly difficult to apply efficiently when grid operation modes change frequently. Although it can demonstrate the dynamic support role of grid-connected equipment, its application in large-scale practical power grids is limited.

[0066] Therefore, one of the core inventive points of this invention is: in order to overcome the shortcomings of the current short-circuit ratio method for multiple new energy power plants and the generalized short-circuit ratio method, a rapid system strength assessment method based on electromechanical transient-electromagnetic transient simulation hybrid drive is proposed for new energy power systems with grid-type power electronic equipment. The implementation approach includes: For a large-scale new energy power system with grid-connected power electronic equipment, firstly, a series of small-scale two-machine systems (grid-connected and grid-connected) are constructed in an electromagnetic transient simulation environment to quickly test the critical short-circuit ratio of various types of grid-connected equipment (to characterize their tolerance to weak power grids) and the equivalent impedance of various types of grid-connected equipment (to characterize their support capacity for weak power grids); secondly, based on electromechanical electromagnetic transient simulation, the generalized short-circuit ratio of the current grid-connected power electronic equipment and the participation factor of the equipment in the generalized short-circuit ratio are quickly calculated; then, the critical short-circuit ratio of each grid-connected equipment is weighted using the participation factor of the generalized short-circuit ratio to obtain the system strength threshold; finally, by comparing the generalized short-circuit ratio and the system strength threshold, it is determined whether the current system strength meets the standard, and a certain stability margin is taken for engineering applications.

[0067] Reference Figure 1This document illustrates a flowchart of a system strength assessment method for a power system provided by an embodiment of the present invention. The power system includes multiple grid-connected devices, each corresponding to one grid-connected device. The method mainly includes an equipment electromagnetic transient simulation stage, a power grid electromechanical transient simulation stage, and a system strength assessment stage. Specifically, the method may include the following steps:

[0068] Step 101: Obtain the grid admittance matrix of the power system, the operating output and critical short-circuit ratio of each of the grid-connected devices under the current operating conditions, and the equivalent impedance of each of the grid-connected devices;

[0069] In practical applications, it is first necessary to obtain the grid admittance matrix of the power system, the operating output and critical short-circuit ratio of each grid-connected device under the current operating conditions, and the equivalent impedance of each grid-connected device, as the basic data for subsequent calculations.

[0070] In some embodiments, the calculation process for the critical short-circuit ratio of each grid-connected device may specifically include: constructing an electromagnetic transient simulation model of the single-machine infinite bus system of the grid-connected device; determining the equivalent impedance of the grid-connected device by adjusting the equivalent impedance of the single-machine infinite bus system based on the judgment of single-machine oscillation instability; setting different operating conditions based on the active power step change adjustment mechanism, and determining the critical short-circuit ratio of the grid-connected device under each operating condition according to the equivalent impedance of the grid.

[0071] Specifically, the first step is modeling grid-connected and grid-building equipment. For a large-scale renewable energy power system containing grid-building power electronic equipment, individual electromagnetic transient simulation models of each grid-connected device (grid-connected renewable energy, grid-connected energy storage, grid-connected reactive power compensation, etc.) and each grid-building device (grid-building energy storage, grid-building reactive power compensation, grid-building renewable energy, etc.) within the system are collected. Simultaneously, the operating modes and typical operating conditions and output of the renewable energy and other grid-connected equipment are determined.

[0072] For the critical short-circuit ratio test of grid-connected devices, an electromagnetic transient simulation model of the individual infinite bus system of each grid-connected device is built in an electromagnetic transient environment (using a commonly used simulation software platform). For each grid-connected device, the equivalent impedance of the grid in the corresponding individual infinite bus system is adjusted until the individual infinite bus system exhibits oscillation and instability. At this point, the equivalent impedance of the grid can be obtained. for:

[0073] ;

[0074] in, The equivalent resistance of the power grid; It is the equivalent reactance of the power grid.

[0075] The critical short-circuit ratio of the network-type equipment can be obtained through testing. :

[0076] ;

[0077] in, For grid short-circuit capacity; To contribute to the network-type equipment.

[0078] Based on the above testing principle, this embodiment of the invention obtains the critical short-circuit ratio of the network-connected equipment under different operating conditions through multiple tests under all possible operating conditions. Specifically, a step change in active power is set. The interval is set to 0.1 pu. This applies to different active power levels. Adjusting the equivalent impedance of the single-unit infinite bus system power grid under different operating conditions (i.e., different operating conditions) During this process, it is necessary to ensure that the terminal voltage of the grid-connected equipment remains at the rated value. When oscillation and instability occur, the operating condition should be determined. The critical short-circuit ratio of the following network devices for:

[0079] ;

[0080] In the formula, This represents the power consumption (operating condition) converted to the current network-connected equipment operating power. The power grid impedance is as follows.

[0081] For the equivalent impedance testing of network-type equipment, in an electromagnetic transient simulation environment, the network-type equipment under test is installed at the grid-connected bus of the corresponding network-type equipment's single-unit infinite bus system. In other words, each network-type equipment is installed at the grid-connected bus of the corresponding network-type equipment's single-unit infinite bus system. A simplified schematic diagram is shown below. Figure 2 As shown.

[0082] In conjunction with the preceding discussion, an electromagnetic transient simulation model of the individual infinite bus system of each grid-connected device is built in an electromagnetic transient environment. By adjusting the equivalent impedance of the grid in the individual infinite bus system until the system exhibits oscillation and instability, this model can be used to test the critical short-circuit ratio of the individual grid-connected device. A grid-connected device is then installed at the grid-connected bus of the individual infinite bus system. Based on the condition that the critical short-circuit ratio of the grid-connected device remains constant, the equivalent impedance of the voltage source of this grid-connected device can be tested.

[0083] Based on the foregoing discussion, in some embodiments, the calculation process for the equivalent impedance of each grid-connected device may specifically include: for each operating condition, keeping the terminal voltage of the grid-connected device constant, adjusting the equivalent impedance of the grid-connected infinite system based on the joint grid-connected oscillation instability judgment to determine the grid-connected critical short-circuit ratio of the infinite system; based on the critical short-circuit ratio and the grid-connected critical short-circuit ratio, back-calculating the joint equivalent impedance of the grid-connected device under the operating condition; and calculating the average value of the joint equivalent impedance under each operating condition to determine the equivalent impedance of the grid-connected device applicable to each operating condition.

[0084] Specifically, under any operating condition of a certain network-connected device Based on the condition that the critical short-circuit ratio of the grid-connected equipment remains unchanged, the equivalent impedance of the grid in the single-unit infinite bus system is adjusted until the grid-connected equipment exhibits oscillation and instability when connected to the infinite bus system. This yields the critical short-circuit ratio of the equipment at the grid connection bus of the grid-connected equipment. It will decrease to:

[0085] ;

[0086] In the formula, This indicates the power converted to the current operating power of the network-type equipment. The combined equivalent impedance of the power grid and grid-connected equipment. Combined with the critical short-circuit ratio of the grid-connected equipment calculated previously. The equivalent impedance modulus of the network-type equipment under this operating condition can be calculated. for:

[0087] ;

[0088] Based on this, in all possible operating conditions of the network-connected equipment The equivalent impedance modulus of the network-type equipment can be obtained through multiple tests and related calculations. Similarly, a step change in active power can be set. The interval is set to 0.1 pu. This applies to different active power levels. Adjusting the equivalent impedance of the infinite power grid system connected to the grid with grid-type equipment. During this process, ensure that the terminal voltage of the grid-connected equipment remains at its rated value. If grid-connected oscillation and instability occur, then determine the equivalent impedance of the grid-connected equipment under this operating condition. After multiple measurements and averaging, the equivalent impedance modulus of this type of network equipment, applicable to all typical operating conditions of the network equipment, can be obtained. for:

[0089] ;

[0090] The method for calculating the equivalent impedance of the aforementioned grid-type equipment is one of the key inventive points that distinguishes this invention from other conventional techniques. The calculation method provided in this embodiment does not rely on methods such as broadband impedance scanning, but can be obtained using a black-box model of the grid-type equipment. Furthermore, the equivalent impedance modulus of all grid-type equipment within the system, including grid-type reactive power compensation, grid-type energy storage, and grid-type new energy, can be calculated one by one using the above method.

[0091] For the grid admittance matrix of the power system In the electromechanical transient simulation model of the power grid, by reading the current operating mode information, performing network topology analysis on the power grid line model, and converting the interconnecting line reactances between each bus to per-unit values, the full-order power grid admittance matrix containing all buses can be obtained. .

[0092] Step 102: Perform a matrix transformation based on node admittance correction according to the grid admittance matrix and each of the equivalent impedances to obtain the grid admittance matrix;

[0093] This step involves performing a matrix transformation based on node admittance correction using the grid admittance matrix and various equivalent impedances to obtain the grid-connected admittance matrix. In some embodiments, the specific implementation process of this step may include: selecting a set of nodes connected to the grid-connected equipment from the grid admittance matrix; each node in the node set corresponds to one grid-connected equipment; correcting the admittance of each node containing the grid-connected equipment in the grid admittance matrix based on various equivalent impedances to obtain a grid-corrected admittance matrix containing the equivalent impedances of the grid-connected equipment; dividing the grid-corrected admittance matrix into blocks according to the grid-connected bus and passive bus of the grid-connected equipment to obtain several block sub-matrices; and constructing a grid-connected admittance matrix that retains the grid-connected bus of the grid-connected equipment through matrix transformation based on several block sub-matrices.

[0094] Specifically, in obtaining the full-order grid admittance matrix including all buses... Based on this, the set of nodes for grid-connected equipment can be selected. The diagonal elements of the grid admittance matrix corresponding to each node are then corrected as follows:

[0095] ;

[0096] This allows us to obtain the grid-corrected admittance matrix, which includes the equivalent impedance of grid-connected equipment. .

[0097] In the electromechanical transient simulation model of the power grid, the current operating mode information is read, network topology analysis is performed on the power grid model, n grid-connected buses for renewable energy, energy storage, and other equipment are selected, and the updated power grid admittance matrix is ​​then analyzed. Perform the following processing: elementary row / column transformations to modify the power grid corrected admittance matrix. Based on the grid-connected busbar and passive busbar of the network-type equipment, the following sections are defined:

[0098] ;

[0099] in, It includes the interconnection susceptance relationship between grid-connected new energy, energy storage and other equipment and their grid-connected busbars; for The block submatrix is ​​calculated using the following formula, retaining the grid admittance matrix of the grid-connected bus for grid-connected new energy, energy storage, and other equipment. :

[0100] ;

[0101] To correspond with the previously mentioned grid admittance matrix To differentiate, embodiments of the present invention will retain the grid admittance matrix of the grid-connected bus for grid-connected new energy, energy storage, and other equipment. Defined as the network admittance matrix.

[0102] Step 103: Calculate the generalized operating short-circuit ratio based on the network admittance matrix and each of the operating outputs;

[0103] This step calculates the generalized operating short-circuit ratio based on the grid admittance matrix and each of the operating outputs. In some embodiments, the specific implementation process of this step may include: constructing a grid output matrix of the power system based on each operating output; constructing an extended admittance matrix based on the grid admittance matrix and the grid output matrix; solving for the minimum eigenvalue of the extended admittance matrix, and using the obtained minimum eigenvalue as the generalized operating short-circuit ratio of the power system considering the supporting role of grid-connected equipment.

[0104] Specifically, in the electromechanical transient simulation model of the power grid, by reading the current operating mode information and based on the operating output of each grid-connected device, an output matrix for grid-connected devices such as new energy sources can be established. :

[0105] ;

[0106] in, For the first The operating output of new energy and other grid-connected equipment.

[0107] In the system strength assessment phase, the Generalized Operating Short Circuit Ratio (gOSCR), which takes into account the supporting role of network-type equipment, can be calculated using the following formula:

[0108] ;

[0109] in, To find the minimum eigenvalue of a matrix, the mature inverse power algorithm can be used. and They represent the extended admittance matrices respectively. Corresponding to the generalized operating short-circuit ratio The normalized left and right eigenvectors satisfy .

[0110] The aforementioned generalized operating short-circuit ratio calculation method is one of the key inventive features that distinguishes this invention from other conventional techniques. This indicator takes into account the voltage support provided by network-type equipment under multiple operating conditions of the system, and is obtained through a hybrid approach combining large-scale electromechanical transient simulation and small-scale electromagnetic transient simulation, making the calculation simple.

[0111] Step 104: Calculate the generalized operating short-circuit ratio threshold based on each of the critical short-circuit ratios and considering the participation factors of the multiple network-connected devices on the generalized operating short-circuit ratio.

[0112] This step calculates the generalized operating short-circuit ratio (GSR) threshold based on each critical short-circuit ratio and considering the participation factors of multiple grid-connected devices on the GSR. In some embodiments, the specific implementation process of this step may include: determining the normalized left and right eigenvectors of the extended admittance matrix corresponding to the GSR based on the extended admittance matrix and the GSR; determining the participation factors of each grid-connected device on the GSR based on the left and right eigenvectors; and obtaining the GSR threshold of the power system by performing a weighted summation calculation based on the critical short-circuit ratio of each grid-connected device and its corresponding participation factor.

[0113] Specifically, this invention calculates the threshold of the generalized operating short-circuit ratio (Critical gOSCR, CgOSCR) of the system strength index using the following formula:

[0114] ;

[0115] in, To match the generalized operating short-circuit ratio of network-type equipment Participating factors; and They are respectively and The Each element. Indicates the first The critical short-circuit ratio of grid-connected new energy and energy storage equipment under current operating conditions is obtained from the relevant steps of the aforementioned electromagnetic transient simulation model test.

[0116] The aforementioned method for calculating the generalized operating short-circuit ratio threshold is also one of the key inventive points that distinguishes this invention from other conventional techniques. Specifically, the use of electromagnetic transient simulation models for both grid-connected and grid-connected equipment allows for the consideration of cross-scale control effects of various types of power electronic equipment. In conjunction with the overall scheme, this embodiment of the invention employs a hybrid approach of large-scale electromechanical transient simulation and small-scale electromagnetic transient simulation. This not only reduces the complexity of system strength assessment and significantly simplifies the analysis process, but also enables targeted and accurate acquisition of system strength and its thresholds, thereby achieving rapid assessment of the strength of new energy power systems containing grid-connected power electronic equipment.

[0117] In other words, this invention eliminates the need for repeated trial-and-error strength threshold adjustments using full electromagnetic transient simulations and the use of broadband impedance measurements, thereby reducing the required computational resources and complexity. This is because conventional techniques, in order to analyze the strength or stability margin of a system, involve large-scale electromagnetic transient simulations of the "entire system," resulting in a large computational load. However, the technical solution provided by this invention can actually be divided into two stages. Stage 1: Small-scale electromagnetic transient simulation of a single-machine infinite bus system connected to a network / networked device (the computational scale and burden are far less than those for simulating the entire large system); Stage 2: The "entire system" only needs to undergo large-scale electromechanical transient simulation (and electromechanical transient calculations are far less complex than electromagnetic transient calculations). Therefore, overall, compared to conventional methods, the technical solution provided by this invention significantly reduces both overall computational resources and complexity.

[0118] Step 105: Evaluate the system strength of the power system based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

[0119] Based on the generalized operating short-circuit ratio and its threshold calculated in the preceding steps, the system strength of the power system can be assessed, and the assessment results obtained. Specifically, the most convenient method is to directly compare the generalized operating short-circuit ratio with its threshold. When the generalized operating short-circuit ratio is greater than the threshold, it indicates that the system is currently in a stable state. In particular, when the generalized operating short-circuit ratio is greater than the threshold and the difference is significant, it indicates that the system is currently in a stable state with a certain stability margin. When the generalized operating short-circuit ratio equals the threshold, it indicates that the system is currently in a critical stability boundary state. In another, less likely case, if the generalized operating short-circuit ratio is less than the threshold, it indicates that the system is currently in an unstable state. To restore the system to a stable operating state as quickly as possible, certain measures need to be taken (such as considering disconnecting some load equipment, appropriately activating grid-connected equipment, reducing the output of grid-connected equipment, etc., which can be set by those skilled in the art according to the actual situation).

[0120] The technical solution of this invention can not only quickly assess the strength level of new energy power systems, but also, based on the assessment results, solve another key problem, namely, determining whether the current strength meets the safety and stability margin requirements of the power system.

[0121] Furthermore, embodiments of the present invention provide a rapid assessment of the stability margin of new energy power systems containing multiple types of grid-connected equipment based on system strength. Based on the calculation results, reference solutions for remedial measures when the system strength is insufficient are provided. Stability margin It can be calculated using the following formula:

[0122] ;

[0123] Based on the preceding discussion, when This indicates that the system is stable and has a certain stability margin; when This indicates that the system is at the critical stability boundary.

[0124] It should be noted that "a stability margin greater than 0 indicates that the system is stable and has a certain stability margin" represents the situation under ideal operating conditions. However, in reality, due to inevitable deviations between simulation models and their analysis methods and actual power grid operating scenarios, such as model uncertainties, a margin can be reserved to ensure the usability of the analysis results. Without a margin, even a slight change in the operating mode could cause the real power grid to fall into the instability region. Therefore, this embodiment of the invention sets a stability margin of 20% as a risk indication threshold for determining whether to adopt remedial measures (a margin of less than 20% is considered a rather "tight" margin range for the safe and stable operation of the power grid).

[0125] Specifically, setting This serves as a critical risk indicator for systems with low stability that require remedial measures. Once the stability margin value exceeds or equals 20%, the system will automatically generate an early warning signal and instruct grid-connected equipment, such as new energy sources, to reduce their output and prioritize the operation of grid-connected equipment that is on standby.

[0126] Specifically, the equivalent impedances of the network devices within the system, obtained from the aforementioned steps, can be sorted from smallest to largest. ( (Number of network-type devices that can be put into operation within the system), indicating equivalent impedance. Smaller grid-connecting devices are prioritized for operation (i.e., devices with equivalent impedance values ​​from smallest to largest are prioritized for deployment from highest to lowest). Based on the participation factors of new energy and other grid-connecting devices obtained in the preceding steps, they are sorted from largest to smallest. The system indicates that new energy grid-connected equipment with a larger participation factor should reduce its output first (i.e., from the largest to the smallest participation factor value, the corresponding equipment should reduce its output first).

[0127] Based on two priority order tables automatically calculated by the system, maintenance personnel can select to deploy corresponding grid-connecting equipment according to priority, or select grid-connecting equipment with reduced output according to priority, or simultaneously implement both schemes depending on the actual situation. Specifically, maintenance personnel can also adopt an automatic remedial scheme of first deploying all grid-connecting equipment, and then reducing the output of grid-connecting equipment if the strength requirement is still not met. When pushing information, the system can also provide suggestions on prioritizing this implementation scheme for maintenance personnel to choose whether to execute. When maintenance personnel confirm the implementation, the system can automatically execute the scheme of prioritizing the deployment of grid-connecting equipment, followed by reducing the output of grid-connecting equipment. After each remedial measure is implemented, the system continuously calculates the stability margin of the new energy power system containing multiple types of grid-connecting equipment until the higher system strength requirement is met, i.e., greater than 20%.

[0128] Taking the commissioning of grid-type equipment as an example, the grid-type equipment is arranged in order of its equivalent impedance from smallest to largest (the smaller the equivalent impedance, the stronger the voltage support capability of the grid-type equipment, and the better the improvement of stability margin). The equipment is then put into operation in sequence as a remedy, and the stability margin of the new energy power system containing multiple types of grid-type equipment is calculated on a rolling basis until the system strength requirement is met (i.e., greater than 20%).

[0129] Therefore, in the specific implementation, after calculating the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold, the stability margin of the power system can be calculated based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold. When the stability margin is less than or equal to the preset stability margin threshold, an early warning signal is generated. Based on the equivalent impedance of each grid-connected device, they are sorted in ascending order of equivalent impedance value to obtain an operation sequence table of grid-connected devices with high to low priority. Based on the participation factor of each grid-connected device in the generalized operating short-circuit ratio, they are sorted in descending order of participation factor value to obtain a power reduction sequence table of grid-connected devices with high to low priority. The early warning signal, the operation sequence table, and the power reduction sequence table are pushed to the system display interface so that operation and maintenance personnel can make decisions based on the operation sequence table and the power reduction sequence table to put grid-connected devices into operation according to the corresponding priority, and / or reduce the operating output of grid-connected devices.

[0130] The aforementioned system strength assessment method and remedial measures based on stability margin are also key inventive points that distinguish this invention from other conventional technical means. On one hand, the embodiments of this invention use the generalized operating short-circuit ratio as the strength assessment index for new energy power systems containing grid-connected power electronic equipment, making this index closely related to power system stability. This allows the system strength assessment results to reflect the stability and stability margin of the new energy power system containing grid-connected power electronic equipment. On the other hand, a risk indication mechanism for remedial measures when system strength is low is set. When the stability margin is small, the system will automatically generate an early warning signal and instruct grid-connected equipment such as new energy sources to reduce output and prioritize the commissioning of grid-connected equipment in dispatch reserves.

[0131] Based on the content described in the preceding embodiments, Figure 3 The diagram illustrates the implementation principle of the rapid strength assessment method for new energy power systems based on hybrid drive of electromechanical transient and electromagnetic transient simulation proposed in this embodiment of the invention.

[0132] It should be noted that the grid-connected equipment in the embodiments of the present invention may include grid-connected new energy, grid-connected energy storage, grid-connected reactive power compensation, and other power electronic equipment that adopts grid-connected control. The grid-building equipment may include grid-building energy storage, grid-building reactive power compensation, grid-building new energy, and other power electronic equipment that adopts grid-building control. It is understood that the present invention does not impose any limitations on these aspects.

[0133] In this embodiment of the invention, a rapid system strength assessment method based on a hybrid driving approach of electromechanical transient and electromagnetic transient simulation is proposed for new energy power systems containing grid-type power electronic equipment. On one hand, by employing electromagnetic transient simulation models of grid-connected and grid-type equipment, the cross-scale control dynamics of various grid-connected and grid-type equipment can be considered, resulting in more accurate system strength calculations. On the other hand, a hybrid driving approach combining large-scale electromechanical transient simulation and small-scale electromagnetic transient simulation enables rapid assessment of the strength of new energy power systems containing grid-type equipment. This method eliminates the need for repeated trial-and-error strength threshold calculations using large-scale full electromagnetic transient simulations and avoids the use of broadband impedance measurements, thus reducing the required computational resources and complexity. In other words, this embodiment of the invention can consider the cross-scale voltage support effects of various grid-type equipment on new energy power systems through small-scale electromagnetic transient simulations, making the calculation of system strength indicators convenient and low-complexity, and suitable for use in actual large-scale power grids. Simultaneously, the generalized operating short-circuit ratio is used as the strength assessment indicator for new energy power systems containing grid-type equipment, ensuring a close relationship between this indicator and power system stability. This allows the system strength assessment results to accurately reflect the stability, stability boundary, and stability margin of new energy power systems containing grid-connected equipment. Furthermore, this invention also constructs a risk indication mechanism for remedial measures when system strength is low. By judging the situation through a risk critical threshold and combining it with automatically generated early warning signals, it prioritizes instructing grid-connected equipment such as new energy sources to reduce output and prioritizing the commissioning of grid-connected equipment in dispatch reserves. This provides operation and maintenance personnel with reference-based risk remediation solutions, helping them to make effective decisions and implement remedial measures.

[0134] For better illustration, refer to Figure 4 This diagram illustrates the overall flow of a power system strength assessment method according to an embodiment of the present invention. It should be noted that this embodiment only provides a brief description of the general flow of power system strength assessment. The specific implementation process of each step can be understood by referring to the relevant content in the foregoing embodiments, and will not be elaborated upon here. It is understood that the present invention does not impose any limitations on this.

[0135] Step 401: Obtain the grid admittance matrix of the power system, and obtain the operating output and critical short-circuit ratio of each grid-connected device under the current operating conditions, as well as the equivalent impedance of each grid-connected device through testing;

[0136] Step 402: Perform a matrix transformation based on node admittance correction according to the grid admittance matrix and each equivalent impedance to obtain the grid admittance matrix, and calculate the generalized operating short-circuit ratio based on the grid admittance matrix and each operating output.

[0137] Step 403: Based on each critical short-circuit ratio, and considering the participation factors of multiple network-connected devices on the generalized operating short-circuit ratio, calculate the generalized operating short-circuit ratio threshold.

[0138] Step 404: Calculate the stability margin of the power system based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold, and automatically generate an early warning signal when the stability margin is less than or equal to the preset stability margin threshold.

[0139] Step 405: Sort the network-type equipment in ascending order of equivalent impedance value to obtain a sequence table of network-type equipment commissioning priority from high to low.

[0140] Step 406: Sort each grid-connected device in descending order of its participation factor value for the generalized operating short-circuit ratio to obtain a power reduction order table for grid-connected devices from high to low priority in reducing power output.

[0141] Step 407: Push the warning signal, the order of operation and the order of output reduction to the system display interface so that the operation and maintenance personnel can make decisions based on the order of operation and the order of output reduction to put network-type equipment into operation according to the corresponding priority, and / or reduce the operating output of network-type equipment.

[0142] Reference Figure 5 The diagram illustrates a structural block diagram of a power system strength assessment device according to an embodiment of the present invention. The power system includes multiple grid-connected devices; each grid-connected device corresponds to one grid-building device; the device may specifically include:

[0143] The data acquisition unit 501 is used to acquire the grid admittance matrix of the power system, the operating output and critical short-circuit ratio of each of the grid-connected devices under the current operating conditions, and the equivalent impedance of each of the grid-connected devices.

[0144] The matrix transformation unit 502 is used to perform a matrix transformation based on node admittance correction according to the grid admittance matrix and each of the equivalent impedances to obtain the grid admittance matrix.

[0145] The generalized operating short-circuit ratio calculation unit 503 is used to calculate the generalized operating short-circuit ratio based on the network admittance matrix and each of the operating outputs;

[0146] The generalized operating short-circuit ratio threshold calculation unit 504 is used to calculate the generalized operating short-circuit ratio threshold based on each of the critical short-circuit ratios, while also considering the participation factors of the multiple network-connected devices on the generalized operating short-circuit ratio.

[0147] The system strength assessment unit 505 is used to assess the system strength of the power system based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

[0148] In one optional embodiment, the device further includes a critical short-circuit ratio calculation unit; the critical short-circuit ratio calculation unit is specifically used for:

[0149] Construct an electromagnetic transient simulation model of the single-machine infinite bus system of the network-connected device;

[0150] The equivalent impedance of the grid-connected equipment is determined by adjusting the equivalent impedance of the single-machine infinite bus system based on the judgment of single-machine oscillation instability.

[0151] Different operating conditions are set based on the active power step change adjustment mechanism, and the critical short-circuit ratio of the grid-connected equipment under each operating condition is determined according to the equivalent impedance of the power grid.

[0152] In one optional embodiment, each of the network-type devices is installed at the grid-connected bus of the corresponding network-type device's single-unit infinite bus system; the device further includes an equivalent impedance calculation unit; the equivalent impedance calculation unit is specifically used for:

[0153] For each of the operating conditions, the terminal voltage of the grid-connected equipment is kept constant. The grid-connected critical short-circuit ratio of the infinite system is determined by adjusting the equivalent impedance of the infinite system after grid connection based on the joint grid-connected oscillation instability judgment.

[0154] Based on the critical short-circuit ratio and the grid-connected critical short-circuit ratio, the combined equivalent impedance of the grid-type equipment under the operating conditions is calculated.

[0155] The average value is calculated based on the combined equivalent impedance under each of the aforementioned operating conditions to determine the equivalent impedance of the network-type equipment applicable to each of the aforementioned operating conditions.

[0156] In one optional embodiment, the matrix transformation unit 502 includes:

[0157] A node set filtering unit is used to filter out the node set to which the grid-type equipment is connected from the power grid admittance matrix; each node in the node set corresponds to one grid-type equipment.

[0158] The node admittance correction unit is used to correct the admittance of each node where the network-type equipment is located in the power grid admittance matrix based on each of the equivalent impedances, so as to obtain a power grid corrected admittance matrix that includes the equivalent impedances of the network-type equipment.

[0159] The matrix partitioning unit is used to partition the power grid correction admittance matrix into several sub-matrices according to the grid-connected bus and passive bus of the grid-type equipment.

[0160] The network admittance matrix construction unit is used to construct a network admittance matrix that retains the grid-connected bus of the network-connected equipment based on the several block sub-matrices through matrix transformation.

[0161] In one optional embodiment, the generalized operating short-circuit ratio calculation unit 503 includes:

[0162] A grid-connected power output matrix construction unit is used to construct the grid-connected power output matrix of the power system based on each of the operating power outputs;

[0163] An extended admittance matrix construction unit is used to construct an extended admittance matrix based on the wire mesh admittance matrix and the wire mesh output matrix.

[0164] The minimum eigenvalue solving unit is used to solve the minimum eigenvalue of the extended admittance matrix, and the obtained minimum eigenvalue is used as the generalized operating short-circuit ratio when the power system considers the supporting role of grid-type equipment.

[0165] In one alternative embodiment, the generalized operating short-circuit ratio threshold calculation unit 504 includes:

[0166] The normalized eigenvector determination unit is used to determine the normalized left and right eigenvectors of the extended admittance matrix corresponding to the generalized operating short-circuit ratio based on the extended admittance matrix and the generalized operating short-circuit ratio.

[0167] The participation factor determination unit is used to determine the participation factor of each of the network-connected devices for the generalized operating short-circuit ratio based on the left feature vector and the right feature vector.

[0168] The weighted summation calculation unit is used to perform weighted summation calculation based on the critical short-circuit ratio of each of the grid-connected devices and the corresponding participation factor to obtain the generalized operating short-circuit ratio threshold of the power system.

[0169] In one alternative embodiment, the device further includes:

[0170] The stability margin calculation unit is used to calculate the stability margin of the power system based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

[0171] The early warning signal generation unit is used to generate an early warning signal when the stability margin is less than or equal to a preset stability margin threshold.

[0172] The unit for constructing the order of operation is used to sort the network-type equipment in ascending order of equivalent impedance based on the equivalent impedance of each equipment, and obtain an order of operation of network-type equipment in descending order of priority.

[0173] The power reduction order table construction unit is used to sort the participation factors of each of the network-connected devices for the generalized operating short-circuit ratio in descending order of participation factor values ​​to obtain a power reduction order table of network-connected devices with high to low power reduction priority.

[0174] The information push unit is used to push the warning signal, the operation sequence table, and the output reduction sequence table to the system display interface, so that operation and maintenance personnel can make decisions based on the operation sequence table and the output reduction sequence table to put network-type equipment into operation according to the corresponding priority, and / or reduce the operating output of network-type equipment.

[0175] As the device embodiment is basically similar to the method embodiment, it is described in a relatively simple way. For relevant details, please refer to the description of the method embodiment above.

[0176] This invention also provides an electronic device, which includes a processor and a memory:

[0177] The memory is used to store program code and transfer the program code to the processor;

[0178] The processor is used to execute the system strength assessment method for a power system according to the instructions in the program code of any embodiment of the present invention.

[0179] This invention also provides a computer-readable storage medium for storing program code for executing the power system strength assessment method of any embodiment of this invention.

[0180] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0181] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this invention are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0182] In the embodiments provided by this invention, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0183] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0184] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0185] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0186] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for assessing the system strength of a power system, characterized in that, The power system includes multiple grid-connected devices; Each of the aforementioned network-type devices corresponds to one network-type device; the method includes: Obtain the grid admittance matrix of the power system, the operating output and critical short-circuit ratio of each of the grid-connected devices under the current operating conditions, and the equivalent impedance of each of the grid-connected devices; The grid admittance matrix is ​​obtained by performing a matrix transformation based on node admittance correction using the grid admittance matrix and each of the equivalent impedances. Based on the network admittance matrix and each of the operating outputs, the generalized operating short-circuit ratio is calculated. Based on each of the aforementioned critical short-circuit ratios, and taking into account the participation factors of the multiple network-connected devices on the generalized operating short-circuit ratio, the generalized operating short-circuit ratio threshold is calculated. The system strength of the power system is assessed based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

2. The system strength assessment method for power systems according to claim 1, characterized in that, The calculation process for the critical short-circuit ratio of each of the aforementioned network devices includes: Construct an electromagnetic transient simulation model of the single-machine infinite bus system of the network-connected device; The equivalent impedance of the grid-connected equipment is determined by adjusting the equivalent impedance of the single-machine infinite bus system based on the judgment of single-machine oscillation instability. Different operating conditions are set based on the active power step change adjustment mechanism, and the critical short-circuit ratio of the grid-connected equipment under each operating condition is determined according to the equivalent impedance of the power grid.

3. The system strength assessment method for power systems according to claim 2, characterized in that, Each of the aforementioned network-type devices is installed at the grid-connected bus of the corresponding network-type device's single-unit infinite bus system; The calculation process for the equivalent impedance of each of the aforementioned network-type devices includes: For each of the operating conditions, the terminal voltage of the grid-connected equipment is kept constant. The grid-connected critical short-circuit ratio of the infinite system is determined by adjusting the equivalent impedance of the infinite system after grid connection based on the joint grid-connected oscillation instability judgment. Based on the critical short-circuit ratio and the grid-connected critical short-circuit ratio, the combined equivalent impedance of the grid-type equipment under the operating conditions is calculated. The average value is calculated based on the combined equivalent impedance under each of the aforementioned operating conditions to determine the equivalent impedance of the network-type equipment applicable to each of the aforementioned operating conditions.

4. The system strength assessment method for power systems according to claim 1, characterized in that, The step of performing a matrix transformation based on nodal admittance correction using the grid admittance matrix and each of the equivalent impedances to obtain the grid admittance matrix includes: The set of nodes to which the grid-type equipment is connected is selected from the grid admittance matrix; each node in the set corresponds to one grid-type equipment. Based on each of the equivalent impedances, the admittance of each node where the network-type equipment is located in the power grid admittance matrix is ​​corrected one by one to obtain a power grid corrected admittance matrix that includes the equivalent impedances of the network-type equipment. The power grid correction admittance matrix is ​​divided into several sub-matrices according to the grid-connected bus and passive bus of the grid-type equipment. Based on the aforementioned sub-matrices, a network admittance matrix that retains the network bus of the network-connected equipment is constructed through matrix transformation.

5. The system strength assessment method for power systems according to claim 1, characterized in that, The calculation of the generalized operating short-circuit ratio based on the network admittance matrix and each of the operating outputs includes: Based on the respective operating outputs, construct the grid-connected output matrix of the power system; Based on the net admittance matrix and the net output matrix, an extended admittance matrix is ​​constructed. The minimum eigenvalue of the extended admittance matrix is ​​solved, and the obtained minimum eigenvalue is used as the generalized operating short-circuit ratio when considering the supporting role of grid-type equipment in the power system.

6. The system strength assessment method for a power system according to claim 5, characterized in that, The step of calculating the generalized operating short-circuit ratio threshold based on each of the critical short-circuit ratios, while simultaneously considering the participation factors of the multiple network-connected devices on the generalized operating short-circuit ratio, includes: Based on the extended admittance matrix and the generalized operating short-circuit ratio, determine the normalized left and right eigenvectors of the extended admittance matrix corresponding to the generalized operating short-circuit ratio; Based on the left feature vector and the right feature vector, the participation factor of each of the network-connected devices in the generalized operating short-circuit ratio is determined; The generalized operating short-circuit ratio threshold of the power system is obtained by weighted summation of the critical short-circuit ratio of each grid-connected device and the corresponding participation factor.

7. The system strength assessment method for a power system according to any one of claims 1 to 6, characterized in that, Also includes: The stability margin of the power system is calculated based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold. When the stability margin is less than or equal to a preset stability margin threshold, an early warning signal is generated; Based on the equivalent impedance of each of the network-type devices, the devices are sorted in ascending order of equivalent impedance value to obtain a sequence table of network-type devices with high to low priority for deployment. Based on the participation factor of each of the network-connected devices for the generalized operating short-circuit ratio, the devices are sorted in descending order of participation factor value to obtain a power reduction order table of network-connected devices from high to low priority in reducing power output. The warning signal, the commissioning sequence table, and the output reduction sequence table are pushed to the system display interface so that maintenance personnel can make decisions based on the commissioning sequence table and the output reduction sequence table to commission network-type equipment according to the corresponding priority, and / or reduce the operating output of network-type equipment.

8. A system strength assessment device for a power system, characterized in that, The power system includes multiple grid-connected devices; Each of the aforementioned network-type devices corresponds to one network-type device; the device includes: The data acquisition unit is used to acquire the grid admittance matrix of the power system, the operating output and critical short-circuit ratio of each of the grid-connected devices under the current operating conditions, and the equivalent impedance of each of the grid-connected devices. The matrix transformation unit is used to perform a matrix transformation based on node admittance correction according to the grid admittance matrix and each of the equivalent impedances to obtain the grid admittance matrix. The generalized operating short-circuit ratio calculation unit is used to calculate the generalized operating short-circuit ratio based on the network admittance matrix and each of the operating outputs; The generalized operating short-circuit ratio threshold calculation unit is used to calculate the generalized operating short-circuit ratio threshold based on each of the critical short-circuit ratios, while also considering the participation factors of the multiple network-connected devices on the generalized operating short-circuit ratio. The system strength assessment unit is used to assess the system strength of the power system based on the generalized operating short-circuit ratio and the generalized operating short-circuit ratio threshold.

9. An electronic device, characterized in that, The device includes a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the system strength assessment method for the power system according to any one of claims 1-7, based on the instructions in the program code.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store program code for executing the system strength assessment method for the power system according to any one of claims 1-7.

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