Broadband oscillation propagation path analysis method of alternating-current and direct-current hybrid system

Abstract

The invention relates to a broadband oscillation propagation path analysis method of an AC-DC hybrid system. The method comprises the following steps: acquiring voltage data and current data of a plurality of key nodes of the AC-DC hybrid system; according to the voltage data and the current data of the plurality of key nodes, determining an oscillation mode of the AC-DC hybrid system; calculating the oscillation power of each key node according to the voltage data and the current data of each key node; according to the current data of each key node and the oscillation power of each key node, determining and collecting an oscillation propagation path of the AC / DC hybrid system; and according to the oscillation propagation path of the AC / DC hybrid system, the oscillation mode of the AC / DC hybrid system and the oscillation power of each key node, calculating an AC / DC coupling propagation coefficient and AC / DC coupling propagation intensity of the AC / DC hybrid system, and determining whether AC / DC coupling propagation exists in the AC / DC hybrid system. And practical guidance can be provided for system operation and control.

Description

Technical Field

[0001] This application relates to the technical field of power system stability analysis, and particularly to a method for analyzing the broadband oscillation propagation path of an AC-DC hybrid system. Background Art

[0002] In recent years, with the large-scale development and utilization of new energy sources such as wind energy and solar energy, the engineering scenarios of their flexible DC transmission have increased day by day, forming a complex AC-DC hybrid system.

[0003] In such complex AC-DC hybrid systems, there are diverse power electronic converters. The interaction of converter controls may cause broadband oscillation problems, and the oscillations may propagate through AC-DC coupling, which poses a threat to the safe and stable operation of the power grid. However, in the prior art, there is a lack of an efficient and accurate oscillation propagation path analysis method applicable to complex AC-DC hybrid systems, and it is impossible to provide guidance for oscillation early warning of the AC-DC hybrid system and taking oscillation control measures. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide a method for analyzing the broadband oscillation propagation path of an AC-DC hybrid system, which can at least accurately identify the oscillation propagation path in the AC-DC hybrid system, quantify the coupling propagation intensity and propagation coefficient of the oscillation between the AC and DC regions, so as to provide practical guidance for system operation and control and improve the stability and reliability of the system.

[0005] In a first aspect, this application provides a method for analyzing the broadband oscillation propagation path of an AC-DC hybrid system, including: collecting voltage data and current data of multiple key nodes of the AC-DC hybrid system, where the multiple key nodes are new energy power station connection points, AC ports and / or DC ports of flexible DC converter stations; determining at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes; calculating the oscillation power of each key node according to the voltage data and current data of each key node; determining at least one oscillation propagation path of the collected AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node; calculating the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity of the collected AC-DC hybrid system according to at least one oscillation propagation path of the collected AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system and the oscillation power of each key node, and determining whether there is AC-DC coupling propagation in the AC-DC hybrid system.

[0006] In one embodiment, the step of determining at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes includes: filtering the voltage data and current data of the multiple key nodes with a band-stop filter having a center frequency of power frequency to remove the power frequency signals in the voltage data and current data of the multiple key nodes; performing frequency-domain analysis on the voltage data and current data of the multiple key nodes after filtering to determine the oscillation frequencies of the multiple key nodes; and determining at least one oscillation mode of the AC-DC hybrid system according to the coupling effect between the oscillation frequencies of the multiple key nodes.

[0007] In one embodiment, the multiple key nodes include multiple AC key nodes and multiple DC key nodes. The AC key nodes include first AC key nodes having only one frequency component in one oscillation mode and second AC key nodes having both a frequency component and its coupled frequency component in one oscillation mode.

[0008] Wherein, the oscillation power of each first key node is calculated by the following formula:

[0009] ;

[0010] Wherein, 、 are respectively the amplitude and phase angle of the oscillation voltage phasor of frequency fp, Ip, are respectively the amplitude and phase angle of the oscillation current phasor of frequency fp;

[0011] Wherein, the oscillation power of each second key node is calculated by the following formula:

[0012] ;

[0013] Wherein, 、 are respectively the amplitude and phase angle of the oscillation voltage phasor of frequency fpc, Ipc, are respectively the amplitude and phase angle of the oscillation current phasor of frequency fpc.

[0014] In one embodiment, the method further includes: if an oscillation mode has a frequency component on the DC side, calculating the oscillation power of each DC key node by the following formula:

[0015] ;

[0016] Wherein, 、 are respectively the amplitude and phase angle of the oscillation voltage phasor of frequency fdc, Idc, They are respectively the amplitude and phase angle of the oscillation current phasor with frequency fdc.

[0017] In one embodiment, at least one oscillation propagation path of the AC-DC hybrid system is determined according to the current data of each key node and the oscillation power of each key node, including:

[0018] S201: Determine multiple first-level key nodes with positive oscillation power from multiple key nodes according to the current reference direction, where the current reference direction is the current direction flowing out of the new energy power station or the flexible DC converter station;

[0019] S202: For each first-level key node, obtain the first-level branches connected to this first-level key node, and determine the key node at the other end of the first-level key branch as the secondary key node;

[0020] S203: For each secondary key node, obtain the secondary branches connected to this secondary key node, and determine whether the key node at the other end connected to this secondary key node is a third-level key node according to the oscillation power of this secondary key node;

[0021] S204: For each third-level key node, obtain the third-level branches connected to this third-level key node, and determine whether the key node at the other end connected to this third-level key node is another third-level node according to the oscillation frequency of this third-level key node;

[0022] S205: If it is determined whether the key node at the other end connected to this third-level key node is another third-level node, then continue to execute step S204 until all third-level nodes in the AC-DC hybrid system are determined;

[0023] S206: Determine at least one oscillation propagation path of the collected AC-DC hybrid system according to multiple first key nodes, multiple secondary key nodes and multiple third-level nodes.

[0024] In one embodiment, the AC-DC hybrid system includes multiple AC regions and multiple DC regions, and the first-level key nodes include first-level AC key nodes and first-level DC key nodes;

[0025] Among them, the AC-DC coupling propagation coefficient of the collected AC-DC hybrid system is calculated through the following steps:

[0026] Obtain the first-level AC key nodes in each AC region and the first-level DC key nodes in each DC region;

[0027] Determine a pair of AC region and DC region that adopt the same flexible DC converter station from the AC-DC hybrid system;

[0028] For each pair of AC regions and DC regions, calculate the AC-DC coupling propagation coefficient between each pair of AC regions and DC regions according to the oscillation power of each key node in the pair of AC regions and DC regions.

[0029] In one embodiment, the AC-DC coupling propagation coefficient between each pair of AC regions and DC regions is calculated by the following formula:

[0030] ;

[0031] where, and respectively represent the oscillation power output by the AC region node Ai and the DC region node Bj.

[0032] In one embodiment, the AC-DC coupling propagation intensity of the collected AC-DC hybrid system is calculated by the following steps:

[0033] For each AC region, if the AC region includes a VSC-HVDC converter station, it is determined that the oscillation propagates from the AC region to the DC region;

[0034] When the oscillation propagates from the AC region to the DC region, there is a negative correlation between the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity.

[0035] In one embodiment, the method includes:

[0036] For each DC region, if the DC region includes a VSC-HVDC converter station, it is determined that the oscillation propagates from the DC region to the AC region;

[0037] When the oscillation propagates from the DC region to the AC region, there is a positive correlation between the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity.

[0038] In one embodiment, the following steps are used to determine whether there is AC-DC coupling propagation in the AC-DC hybrid system:

[0039] Identify the oscillation modes in the AC region and the DC region, and determine whether each oscillation mode can be identified in both the AC region and the DC region;

[0040] For each oscillation mode, if the oscillation mode can be identified in both the AC region and the DC region, it is determined that the oscillation mode propagates through AC-DC coupling.

[0041] In a second aspect, the present application also provides a wide-frequency oscillation propagation path analysis device for an AC-DC hybrid system, including a data acquisition module, an oscillation mode determination module, an oscillation power determination module, an oscillation propagation path determination module, and a coupling data calculation module,

[0042] A data acquisition module for acquiring voltage data and current data of multiple key nodes of an AC-DC hybrid system, where the multiple key nodes are the grid connection points of new energy power stations, AC ports and / or DC ports of flexible DC converter stations;

[0043] An oscillation mode determination module for determining at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes;

[0044] An oscillation power determination module for calculating the oscillation power of each key node according to the voltage data and current data of each key node;

[0045] An oscillation propagation path determination module for determining at least one oscillation propagation path of the acquired AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node;

[0046] A coupling data calculation module for calculating the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity of the acquired AC-DC hybrid system according to at least one oscillation propagation path of the acquired AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system, and the oscillation power of each key node, and determining whether there is AC-DC coupling propagation in the AC-DC hybrid system.

[0047] In a third aspect, the present application also provides a computer device, including a memory and a processor, where the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0048] Acquiring voltage data and current data of multiple key nodes of an AC-DC hybrid system, where the multiple key nodes are the grid connection points of new energy power stations, AC ports and / or DC ports of flexible DC converter stations;

[0049] Determining at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes;

[0050] Calculating the oscillation power of each key node according to the voltage data and current data of each key node;

[0051] Determining at least one oscillation propagation path of the acquired AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node;

[0052] Calculating the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity of the acquired AC-DC hybrid system according to at least one oscillation propagation path of the acquired AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system, and the oscillation power of each key node, and determining whether there is AC-DC coupling propagation in the AC-DC hybrid system.

[0053] Fourthly, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0054] Collect voltage data and current data of multiple key nodes of the AC-DC hybrid system, where the multiple key nodes are the grid connection points of new energy power stations, AC ports and / or DC ports of flexible DC converter stations;

[0055] Determine at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes;

[0056] Calculate the oscillation power of each key node according to the voltage data and current data of each key node;

[0057] Determine at least one oscillation propagation path of the collected AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node;

[0058] Calculate the AC-DC coupling propagation coefficient and AC-DC coupling propagation intensity of the collected AC-DC hybrid system, and determine whether there is AC-DC coupling propagation in the AC-DC hybrid system according to at least one oscillation propagation path of the collected AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system, and the oscillation power of each key node.

[0059] Fifthly, the present application also provides a computer program product, including a computer program. When the computer program is executed by a processor, the following steps are implemented:

[0060] Collect voltage data and current data of multiple key nodes of the AC-DC hybrid system, where the multiple key nodes are the grid connection points of new energy power stations, AC ports and / or DC ports of flexible DC converter stations;

[0061] Determine at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes;

[0062] Calculate the oscillation power of each key node according to the voltage data and current data of each key node;

[0063] Determine at least one oscillation propagation path of the collected AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node;

[0064] Calculate the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity of the AC-DC hybrid system according to at least one oscillation propagation path of the AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system, and the oscillation power of each key node, and determine whether there is AC-DC coupling propagation in the AC-DC hybrid system.

[0065] The above method for analyzing the broadband oscillation propagation path of the AC-DC hybrid system can at least accurately identify the oscillation propagation path in the AC-DC hybrid system, quantify the coupling propagation intensity and propagation coefficient of the oscillation between the AC and DC regions, thereby providing practical guidance for system operation and control, and improving the stability and reliability of the system. Brief Description of the Drawings

[0066] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description in the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0067] Figure 1 It is a schematic flowchart of a method for analyzing the broadband oscillation propagation path of an AC-DC hybrid system in one embodiment;

[0068] Figure 2 It is a schematic flowchart of a method for analyzing the broadband oscillation propagation path of an AC-DC hybrid system in another embodiment;

[0069] Figure 3 It is a structural block diagram of a device for analyzing the broadband oscillation propagation path of an AC-DC hybrid system in one embodiment;

[0070] Figure 4 It is an internal structure diagram of a computer device in one embodiment.

[0071] Reference Signs and Descriptions:

[0072] 10. Data acquisition module; 20. Oscillation mode determination module; 30. Oscillation power determination module; 40. Oscillation propagation path determination module; 50. Coupling data calculation module. Detailed Description of the Embodiments

[0073] In order to make the purpose, technical solutions and advantages of the present application clearer, the following further details the present application with reference to the drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0074] The entity recognition method in multi-turn question answering provided by the embodiments of the present application can be applied to various personal computers, laptop computers, smart phones, tablet computers, Internet of Things devices, and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart in-vehicle devices, projection devices, etc. The portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. The head-mounted devices can be virtual reality (VR) devices, augmented reality (AR) devices, smart glasses, etc.

[0075] Please refer to Figure 1 , in an exemplary embodiment, a method for analyzing the broadband oscillation propagation path of an AC-DC hybrid system is provided, including:

[0076] Step S101, collecting voltage data and current data of multiple key nodes of the AC-DC hybrid system.

[0077] Among them, the multiple key nodes are the grid connection points of new energy power stations, the AC ports and / or DC ports of flexible DC converter stations.

[0078] Here, these key nodes play important roles in electrical connection and energy exchange in the system and are key observation points for oscillation phenomena.

[0079] Step S102, determining at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes.

[0080] Specifically, determining at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes includes: filtering the voltage data and current data of the multiple key nodes with a band-stop filter centered at the power frequency to remove the power frequency signals in the voltage data and current data of the multiple key nodes; performing frequency-domain analysis on the filtered voltage data and current data of the multiple key nodes to determine the oscillation frequencies of the multiple key nodes; and determining at least one oscillation mode of the AC-DC hybrid system according to the coupling effect between the oscillation frequencies of the multiple key nodes.

[0081] Here, filtering is performed through a band-stop filter centered at the power frequency to remove the power frequency signals and retain the oscillation-related signals.

[0082] Here, for frequency-domain analysis of the filtered node voltage and current signals, a fast Fourier transform (FFT) algorithm based on windowed interpolation can be used. Set an amplitude threshold, search for all maximum points in the frequency-domain transformation result whose amplitudes are greater than the threshold, and record the frequency of each maximum point as an oscillation frequency.

[0083] Optionally, the oscillation frequencies of all key nodes can be taken as the union to form a complete set of oscillation frequencies.

[0084] Here, due to the control action of the converter, there is sometimes an obvious frequency coupling effect in the system oscillation frequency, which is manifested as follows: when oscillation occurs, there will be a dominant oscillation component with frequency fp and a coupled oscillation component with frequency fpc in the AC side voltage and current of the system, where fpc = |2fn – fp| and fn is the power frequency; at the same time, an oscillation component with frequency fdc =|fn – fp| may appear on the DC side of the system. The oscillation frequencies of fp and fpc on the AC side and the oscillation frequency of fdc on the DC side are regarded as the same oscillation mode.

[0085] Specifically, if there is the above-mentioned coupling relationship between two or more of the oscillation frequencies, they are regarded as the same oscillation mode; for the oscillation frequencies that have no coupling with other oscillation frequencies, it is considered that this frequency corresponds to an independent oscillation mode, indicating that the frequency coupling effect in the system is not obvious at this time.

[0086] Step S103, calculate the oscillation power of each key node according to the voltage data and current data of each key node.

[0087] Specifically, the multiple key nodes include multiple AC key nodes and multiple DC key nodes. The AC key nodes include first AC key nodes with only one frequency component in one oscillation mode and second AC key nodes with both a frequency component and its coupled frequency component in one oscillation mode.

[0088] Among them, the oscillation power of each first key node is calculated by the following formula:

[0089] ;

[0090] Among them, , are respectively the amplitude and phase angle of the oscillation voltage phasor of frequency fp, Ip, are respectively the amplitude and phase angle of the oscillation current phasor of frequency fp;

[0091] Among them, the oscillation power of each second key node is calculated by the following formula:

[0092] ;

[0093] Among them, , are respectively the amplitude and phase angle of the oscillation voltage phasor of frequency fpc, Ipc, are respectively the amplitude and phase angle of the oscillation current phasor of frequency fpc.

[0094] Specifically, the method further includes: if an oscillation mode has a frequency component on the DC side, calculating the oscillation power of each DC critical node through the following formula:

[0095] ;

[0096] wherein, , are respectively the amplitude and phase angle of the oscillation voltage phasor of the frequency fdc, and Idc, are respectively the amplitude and phase angle of the oscillation current phasor of the frequency fdc.

[0097] Step S104, determining at least one oscillation propagation path of the collected AC-DC hybrid system according to the current data of each critical node and the oscillation power of each critical node.

[0098] Specifically, please refer to Figure 2 , determining at least one oscillation propagation path of the AC-DC hybrid system according to the current data of each critical node and the oscillation power of each critical node, including:

[0099] S201: According to the current reference direction, determining multiple primary critical nodes with positive oscillation power from multiple critical nodes, where the current reference direction is the current direction flowing out of the new energy power station or the flexible DC converter station.

[0100] S202: For each primary critical node, obtaining the primary branch connected to this primary critical node, and determining the critical node at the other end of the primary critical branch as the secondary critical node.

[0101] S203: For each secondary critical node, obtaining the secondary branch connected to this secondary critical node, and determining whether the critical node at the other end connected to this secondary critical node is a tertiary critical node according to the oscillation power of this secondary critical node.

[0102] S204: For each tertiary critical node, obtaining the tertiary branch connected to this tertiary critical node, and determining whether the critical node at the other end connected to this tertiary critical node is another tertiary node according to the oscillation frequency of this tertiary critical node.

[0103] S205 (not shown in the figure): If it is determined whether the critical node at the other end connected to this tertiary critical node is another tertiary node, then continue to execute step S204 until all tertiary nodes in the collected AC-DC hybrid system are determined.

[0104] S206: Determining at least one oscillation propagation path of the collected AC-DC hybrid system according to multiple first critical nodes, multiple secondary critical nodes and multiple tertiary nodes.

[0105] Specifically, the steps of determining whether the key node at the other end connected to the secondary key node is a tertiary key node or determining whether the key node at the other end connected to the tertiary key node is another tertiary node include: If the oscillating power flowing from the secondary node or the tertiary node to a certain branch is positive and greater than a preset threshold, then the node at the other end of this branch is used as the tertiary node for oscillating propagation.

[0106] Here, the preset threshold can be adjusted according to the specific situation of the system to ensure an accurate oscillating propagation path.

[0107] Furthermore, by sorting the oscillating powers of the primary nodes of oscillating propagation, the dominant equipment of the oscillation can be identified, thereby providing guidance for taking effective oscillation control.

[0108] Step S105, calculate the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity of the collected AC-DC hybrid system according to at least one oscillating propagation path of the collected AC-DC hybrid system, at least one oscillating mode of the AC-DC hybrid system, and the oscillating power of each key node, and determine whether there is AC-DC coupling propagation in the AC-DC hybrid system.

[0109] Specifically, the AC-DC hybrid system includes multiple AC regions and multiple DC regions, and the primary key nodes include primary AC key nodes and primary DC key nodes.

[0110] Among them, the AC-DC coupling propagation coefficient of the collected AC-DC hybrid system is calculated through the following steps: Obtain the primary AC key nodes in each AC region and the primary DC key nodes in each DC region; Determine a pair of AC region and DC region that use the same flexible DC converter station from the AC-DC hybrid system; For each pair of AC region and DC region, calculate the AC-DC coupling propagation coefficient between each pair of AC region and DC region according to the oscillating power of each key node in this pair of AC region and DC region.

[0111] Among them, the AC-DC coupling propagation coefficient between each pair of AC region and DC region is calculated through the following formula:

[0112] ;

[0113] Among them, and respectively represent the oscillating powers output by the AC region node Ai and the DC region node Bj.

[0114] Specifically, the AC-DC coupling propagation intensity of the collected AC-DC hybrid system is calculated through the following steps: For each AC region, if the flexible DC converter station is included in the AC region, it is determined that the oscillation propagates from the AC region to the DC region; when the oscillation propagates from the AC region to the DC region, there is a negative correlation between the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity.

[0115] Specifically, the method includes: For each DC region, if the flexible DC converter station is included in the DC region, it is determined that the oscillation propagates from the DC region to the AC region; when the oscillation propagates from the DC region to the AC region, there is a positive correlation between the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity.

[0116] As an example, when the oscillation is transmitted from the DC side to the AC side of the flexible DC converter station, the smaller the KCP, the greater the coupling propagation intensity of the oscillation between the above AC and DC regions; when the oscillation is transmitted from the AC side to the DC side of the flexible DC converter station, the greater the KCP, the greater the coupling propagation intensity of the oscillation between the above AC and DC regions.

[0117] Specifically, the following steps are used to determine whether there is AC-DC coupling propagation in the AC-DC hybrid system: Identify the oscillation modes in the AC region and the DC region, and determine whether each oscillation mode can be identified in both the AC region and the DC region; for each oscillation mode, if the oscillation mode can be identified in both the AC region and the DC region, it is determined that the oscillation mode propagates through AC-DC coupling.

[0118] It should be understood that although the steps in the flowcharts involved in the above embodiments are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise clearly stated in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover, at least some of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least some of the steps or stages in other steps or other steps.

[0119] Based on the same inventive concept, an embodiment of the present application further provides an analysis device for the broadband oscillation propagation path of an AC-DC hybrid system for implementing the above-mentioned analysis method of the broadband oscillation propagation path of the AC-DC hybrid system. The solution provided by this device to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the analysis device for the broadband oscillation propagation path of the AC-DC hybrid system provided below can refer to the limitations on the analysis method of the broadband oscillation propagation path of the AC-DC hybrid system in the above text, and will not be repeated here.

[0120] Please refer to Figure 3 , in an exemplary embodiment, an analysis device for the broadband oscillation propagation path of an AC-DC hybrid system is provided, including: a data acquisition module 10, an oscillation mode determination module 20, an oscillation power determination module 30, an oscillation propagation path determination module 40, and a coupling data calculation module 50. The data acquisition module is configured to acquire voltage data and current data of multiple key nodes of the AC-DC hybrid system, and the multiple key nodes are new energy power station connection points, AC ports and / or DC ports of flexible DC converter stations; the oscillation mode determination module is configured to determine at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes; the oscillation power determination module is configured to calculate the oscillation power of each key node according to the voltage data and current data of each key node; the oscillation propagation path determination module is configured to determine at least one oscillation propagation path of the acquired AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node; the coupling data calculation module is configured to calculate the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity of the acquired AC-DC hybrid system according to at least one oscillation propagation path of the acquired AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system, and the oscillation power of each key node, and determine whether there is AC-DC coupling propagation in the AC-DC hybrid system.

[0121] Each module in the above analysis device for the broadband oscillation propagation path of the AC-DC hybrid system can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor of the computer device in hardware form or be independent of it, or can be stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above modules.

[0122] In an exemplary embodiment, a computer device is provided, which may be a terminal. The computer device includes a processor, a memory, an input / output interface, a communication interface, a display unit, and an input device. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface, the display unit, and the input device are connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with external terminals in a wired or wireless manner, and the wireless manner can be implemented through WIFI, a mobile cellular network, near field communication (NFC), or other technologies. When the computer program is executed by the processor, it implements a method for analyzing the broadband oscillation propagation path of an AC-DC hybrid system. The display unit of the computer device is used to form a visually visible picture, which may be a display screen, a projection device, or a virtual reality imaging device. The display screen may be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device may be a touch layer covered on the display screen, or a button, a trackball, or a touchpad provided on the housing of the computer device, or an external keyboard, touchpad, or mouse, etc.

[0123] Those skilled in the art can understand that Figure 4 the structure shown in is only a block diagram of some structures related to the solution of this application, and does not constitute a limitation on the computer device to which the solution of this application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0124] In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, the following steps are implemented:

[0125] Collect voltage data and current data of multiple key nodes of the AC-DC hybrid system, where the multiple key nodes are new energy power station connection points, AC ports and / or DC ports of a flexible DC converter station;

[0126] Determine at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes;

[0127] Calculate the oscillation power of each key node according to the voltage data and current data of each key node;

[0128] Determine at least one oscillation propagation path of the collected AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node;

[0129] Calculate the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity of the collected AC-DC hybrid system according to at least one oscillation propagation path of the collected AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system, and the oscillation power of each key node, and determine whether there is AC-DC coupling propagation in the AC-DC hybrid system.

[0130] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0131] Collect voltage data and current data of multiple key nodes of the AC-DC hybrid system, where the multiple key nodes are new energy power station connection points, AC ports and / or DC ports of flexible DC converter stations;

[0132] Determine at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes;

[0133] Calculate the oscillation power of each key node according to the voltage data and current data of each key node;

[0134] Determine at least one oscillation propagation path of the collected AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node;

[0135] Calculate the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity of the collected AC-DC hybrid system according to at least one oscillation propagation path of the collected AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system, and the oscillation power of each key node, and determine whether there is AC-DC coupling propagation in the AC-DC hybrid system.

[0136] In one embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the following steps are implemented:

[0137] Collect voltage data and current data of multiple key nodes of the AC-DC hybrid system, where the multiple key nodes are new energy power station connection points, AC ports and / or DC ports of flexible DC converter stations;

[0138] Determine at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes;

[0139] Calculate the oscillation power of each key node according to the voltage data and current data of each key node;

[0140] Determine at least one oscillation propagation path of the collected AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node;

[0141] Calculate the AC-DC coupling propagation coefficient and AC-DC coupling propagation intensity of the collected AC-DC hybrid system according to at least one oscillation propagation path of the collected AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system and the oscillation power of each key node, and determine whether there is AC-DC coupling propagation in the AC-DC hybrid system.

[0142] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, data processing logics based on quantum computing, artificial intelligence (AI) processors, etc., without limitation.

[0143] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope recorded in the present application.

[0144] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for analyzing the broadband oscillation propagation path of an AC-DC hybrid system, characterized in that, The method includes: Collecting voltage data and current data of multiple key nodes of an AC-DC hybrid system, where the multiple key nodes are the grid connection points of new energy power stations, the AC ports and / or DC ports of flexible DC converter stations; Determining at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes; Calculating the oscillation power of each key node according to the voltage data and current data of each key node; Determining at least one oscillation propagation path of the collected AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node; Calculating the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity of the collected AC-DC hybrid system, and determining whether there is AC-DC coupling propagation in the AC-DC hybrid system according to at least one oscillation propagation path of the collected AC-DC hybrid system, at least one oscillation mode of the AC-DC hybrid system, and the oscillation power of each key node.

2. The method according to claim 1, characterized in that Determining at least one oscillation mode of the AC-DC hybrid system according to the voltage data and current data of the multiple key nodes includes: Filtering the voltage data and current data of the multiple key nodes with a band-stop filter centered at the power frequency to remove the power frequency signals in the voltage data and current data of the multiple key nodes; Performing frequency-domain analysis on the voltage data and current data of the multiple key nodes after filtering to determine the oscillation frequencies of the multiple key nodes; Determining at least one oscillation mode of the AC-DC hybrid system according to the coupling effect between the oscillation frequencies of the multiple key nodes.

3. The method according to claim 1, wherein The multiple key nodes include multiple AC key nodes and multiple DC key nodes. The AC key nodes include first AC key nodes with only one frequency component in one oscillation mode and second AC key nodes with both a frequency component and its coupled frequency component in one oscillation mode; Among them, the oscillation power of each first key node is calculated by the following formula: ； wherein, and are the amplitude and phase angle of the oscillation voltage phasor at the frequency fp, and Ip and are the amplitude and phase angle of the oscillation current phasor at the frequency fp; Among them, the oscillation power of each second key node is calculated by the following formula: ； Among them, and are the amplitude and phase angle of the oscillation voltage phasor of the frequency fpc, respectively. Ipc and are the amplitude and phase angle of the oscillation current phasor of the frequency fpc, respectively.

4. The method according to claim 3, characterized in that The method further includes: if an oscillation mode has a frequency component on the DC side, calculating the oscillation power of each DC key node by the following formula: ； Among them, , are respectively the amplitude and phase angle of the oscillation voltage phasor of the frequency fdc, and Idc, are respectively the amplitude and phase angle of the oscillation current phasor of the frequency fdc.

5. The method according to claim 4, wherein Determining at least one oscillation propagation path of the AC-DC hybrid system according to the current data of each key node and the oscillation power of each key node includes: S201: Determining multiple primary key nodes with positive oscillation power from the multiple key nodes according to the current reference direction, where the current reference direction is the current direction flowing out of the new energy power station or the flexible DC converter station; S202: For each primary key node, obtaining the primary branch connected to the primary key node, and determining the key node at the other end of the primary key branch as the secondary key node; S203: For each secondary key node, obtaining the secondary branch connected to the secondary key node, and determining whether the key node at the other end connected to the secondary key node is a tertiary key node according to the oscillation power of the secondary key node; S204: For each third-level key node, obtain the third-level branches connected to this third-level key node, and based on the oscillation frequency of this third-level key node, determine whether the key node at the other end connected to this third-level key node is another third-level node; S205: If it is determined whether the key node at the other end connected to this third-level key node is another third-level node, then continue to execute step S204 until it is determined that all third-level nodes in the AC-DC hybrid system are collected; S206: Based on multiple first-level key nodes, multiple secondary key nodes, and multiple third-level nodes, determine at least one oscillation propagation path of the collected AC-DC hybrid system.

6. The method according to claim 1, characterized in that The AC-DC hybrid system includes multiple AC regions and multiple DC regions, and the first-level key nodes include first-level AC key nodes and first-level DC key nodes; Among them, the AC-DC coupling propagation coefficient of the collected AC-DC hybrid system is calculated through the following steps: Obtain the first-level AC key nodes in each AC region and the first-level DC key nodes in each DC region; Determine a pair of AC region and DC region that use the same flexible DC converter station from the AC-DC hybrid system; For each pair of AC region and DC region, calculate the AC-DC coupling propagation coefficient between each pair of AC region and DC region according to the oscillation power of each key node in this pair of AC region and DC region.

7. The method according to claim 6, characterized in that The AC-DC coupling propagation coefficient between each pair of AC region and DC region is calculated through the following formula: ； Among them, and respectively represent the oscillating power output by the AC regional node Ai and the DC regional node Bj.

8. The method according to claim 7, wherein The AC-DC coupling propagation intensity of the collected AC-DC hybrid system is calculated through the following steps: For each AC region, if this AC region includes a flexible DC converter station, then determine that the oscillation propagates from the AC region to the DC region; When the oscillation propagates from the AC region to the DC region, there is a negative correlation between the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity.

9. The method according to claim 8, wherein The method includes: For each DC region, if this DC region includes a flexible DC converter station, then determine that the oscillation propagates from the DC region to the AC region; When the oscillation propagates from the DC region to the AC region, there is a positive correlation between the AC-DC coupling propagation coefficient and the AC-DC coupling propagation intensity.

10. The method according to claim 6, characterized in that The following steps are used to determine whether there is AC-DC coupling propagation in the AC-DC hybrid system: Identify the oscillation modes in the AC region and the DC region, and determine whether each oscillation mode can be identified in both the AC region and the DC region; For each oscillation mode, if this oscillation mode can be identified in both the AC region and the DC region, then determine that this oscillation mode propagates through AC-DC coupling.

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