Power system oscillation risk assessment method, system, computer equipment and medium

Abstract

The present invention belongs to the field of electric power automation and discloses a power system oscillation risk assessment method, system, computer equipment, and medium. The method includes real-time monitoring of power system measurement data, determining whether subsynchronous / supersynchronous interharmonics exist in the power system based on the measurement data, obtaining the frequency, amplitude, and voltage-current angle difference of the subsynchronous / supersynchronous interharmonics, and combining the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in historical record data to obtain an oscillation risk assessment result for the subsynchronous / supersynchronous interharmonics; supplementing the frequency and amplitude of the subsynchronous / supersynchronous interharmonics with oscillation risk in the oscillation risk assessment result to the historical record data, and updating the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data. Oscillation risk assessment is performed based on real-time data and historical record data, improving the accuracy of the oscillation risk assessment result and reducing the false alarm rate.

Description

Technical Field

[0001] The present invention belongs to the field of electric power automation and relates to a method, system, computer equipment and medium for evaluating the risk of power system oscillation. Background Art

[0002] In recent years, the power system has undergone profound changes, entering an era of wide-area interconnection characterized by large-scale units, long distances, ultra-high voltage (UHV), AC / DC hybrids, and high penetration of renewable energy. The widespread application of power electronics technologies, such as UHV, rail transit, and renewable energy, has significantly altered the characteristics of the power system, with the "source-grid-load" model taking on a power-electronics-based character. Furthermore, with the development of new power systems, an increasing number of renewable energy sources will be connected to the power system, injecting a large amount of non-power-frequency electrical energy into the system, significantly increasing the probability of low-frequency oscillations and sub- and super-synchronous oscillations.

[0003] In addition, with the rapid development of new energy sources such as wind power, the subsynchronous oscillation problem caused by it and the AC and DC power grids is particularly prominent. Historical accident experience shows that the subsynchronous oscillation problem of the power system has a wide impact range and has endangered the safe and stable operation of the power system. Moreover, its inducing factors are uncertain, which has brought great obstacles to the formulation and implementation of suppression measures. Therefore, it is necessary to carry out subsynchronous / supersynchronous oscillation risk assessment of the power system.

[0004] Currently, the main methods for assessing subsynchronous and supersynchronous oscillation risks in power systems include short-circuit ratio-based assessments and impedance-based assessments. However, these assessment methods are all based on offline historical measurement data, using frequency sweeps to obtain impedance or modeling to obtain the resonant frequency. However, oscillation risk is related to power system operating parameters, and changes in these parameters, especially the resonant frequency, can lead to changes in the power system's operating mode. This results in inaccurate assessment results from existing oscillation risk assessment methods. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method, system, computer equipment and medium for power system oscillation risk assessment.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for assessing the oscillation risk of an electric power system, comprising: monitoring the measurement data of the electric power system in real time, and determining whether sub / supersynchronous oscillation interharmonics exist in the electric power system based on the measurement data; and when sub / supersynchronous oscillation interharmonics exist in the electric power system, obtaining the frequency, amplitude, and voltage-current angle difference of the sub / supersynchronous oscillation interharmonics; performing data trend calculation and logical judgment based on the frequency, amplitude, and voltage-current angle difference of the sub / supersynchronous oscillation interharmonics, and in combination with the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in historical record data to obtain an oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics; adding the frequency and amplitude of the sub / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment result to the historical record data, and updating the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data.

[0008] Optionally, when sub / super synchronous oscillation interharmonics exist in the power system, obtaining the frequency, amplitude and voltage-current angle difference of the sub / super synchronous oscillation interharmonics includes: obtaining each interharmonic of voltage or current excluding the fundamental wave; sorting each interharmonic in order of amplitude from large to small, and using the first N interharmonics in the sorting as sub / super synchronous oscillation interharmonics for evaluation; wherein N is a preset constant; obtaining the frequency, amplitude and voltage-current angle difference of each sub / super synchronous oscillation interharmonic.

[0009] Optionally, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is obtained by performing data trend calculation and logical judgment based on the frequency, amplitude and voltage-current angle difference of the sub / supersynchronous oscillation interharmonics, and combining the torsional vibration frequency, each oscillation risk frequency and the amplitude threshold of each oscillation risk frequency in the historical record data, including: obtaining the difference between the frequency of the sub / supersynchronous oscillation interharmonics and the torsional vibration frequency; when the difference is less than a preset difference threshold, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is the highest level oscillation risk; when the difference is not less than the preset difference threshold, judging whether there is an oscillation risk frequency with the same frequency as the sub / supersynchronous oscillation interharmonics in each oscillation risk frequency; when there is no oscillation risk frequency with the same frequency as the sub / supersynchronous oscillation interharmonics, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is the occurrence of a new oscillation risk; when there is an oscillation risk frequency with the same frequency as the sub / supersynchronous oscillation interharmonics, taking the same oscillation risk frequency as the target oscillation risk frequency; obtaining the sub / supersynchronous oscillation interharmonics according to the amplitude threshold of the target oscillation risk frequency. The amplitude assessment threshold value of the synchronous oscillation interharmonics is used, and the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is obtained through the following assessment logic: when conditions 1, 2, and 3 are met, the oscillation risk assessment result is a first-level oscillation risk; when condition 2 or condition 2 and 3 are met, the oscillation risk assessment result is a second-level oscillation risk; when conditions 1, 1, and 2, or condition 1 and 3 are met, the oscillation risk assessment result is a third-level oscillation risk; when only condition 3 is met, the oscillation risk assessment result is a fourth-level oscillation risk; when conditions 1, 2, and 3 are not met, the oscillation risk assessment result is no risk warning; among them, condition 1: the amplitude of the sub / supersynchronous oscillation interharmonic is greater than the amplitude assessment threshold value, and the duration is greater than the first preset time threshold; condition 2: the amplitude of the sub / supersynchronous oscillation interharmonic continues to amplify for a time greater than the second preset time threshold; condition 3: the sign of the cosθ value of the sub / supersynchronous oscillation interharmonic is consistent with the sign of the inflow bus, and the duration is greater than the third preset time threshold; among them, θ is the voltage and current angle difference.

[0010] Optionally, the frequency and amplitude of the sub / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment result are added to the historical record data, and the torsional vibration frequency, each oscillation risk frequency and the amplitude threshold of each oscillation risk frequency in the historical record data are updated, including: obtaining the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency, and taking the average of the torsional vibration frequency and the frequency of the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency as the new torsional vibration frequency; traversing each oscillation risk frequency: obtaining the target sub / supersynchronous oscillation interharmonic of the current oscillation risk frequency, and taking the average of the amplitude threshold of the current oscillation risk frequency and the amplitude of the target sub / supersynchronous oscillation interharmonic of the current oscillation risk frequency as the new amplitude threshold of the current oscillation risk frequency; eliminating the torsional vibration in the sub / supersynchronous oscillation interharmonic The target sub / supersynchronous oscillation interharmonic of the frequency and the target sub / supersynchronous oscillation interharmonic of each oscillation risk frequency are used to obtain the remaining sub / supersynchronous oscillation interharmonics; and when the remaining sub / supersynchronous oscillation interharmonics are not empty, each remaining sub / supersynchronous oscillation interharmonic is traversed: the current remaining sub / supersynchronous oscillation interharmonic is used as the oscillation risk frequency, and the amplitude of the current remaining sub / supersynchronous oscillation interharmonic is used as the amplitude threshold of the current oscillation risk frequency; wherein, the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with the torsional vibration frequency less than a first preset difference threshold; the target sub / supersynchronous oscillation interharmonic of each oscillation risk frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with each oscillation risk frequency less than a second preset threshold.

[0011] Optionally, the torsional vibration frequency is set to the complementary frequency of the torsional vibration frequency of the generator shaft system within a preset range of the power system during initialization; and the historical record data is the historical record data under the current load level of the power system.

[0012] Optionally, it also includes: obtaining and recording the duration of sub / supersynchronous oscillation interharmonics with oscillation risks in the oscillation risk assessment results, the final form of oscillation, and long-wave recording data within the duration of sub / supersynchronous oscillation interharmonics.

[0013] According to a second aspect of the present invention, a power system oscillation risk assessment system is provided, comprising: a data acquisition module for monitoring the measurement data of the power system in real time, and determining whether there are sub / supersynchronous oscillation interharmonics in the power system based on the measurement data; and when there are sub / supersynchronous oscillation interharmonics in the power system, obtaining the frequency, amplitude and voltage-current angle difference of the sub / supersynchronous oscillation interharmonics; an oscillation risk assessment module for performing data trend calculation and logical judgment based on the frequency, amplitude and voltage-current angle difference of the sub / supersynchronous oscillation interharmonics, and in combination with the torsional vibration frequency, each oscillation risk frequency and the amplitude threshold of each oscillation risk frequency in the historical record data, to obtain an oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics; and a data update module for adding the frequency and amplitude of the sub / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment result to the historical record data, and updating the torsional vibration frequency, each oscillation risk frequency and the amplitude threshold of each oscillation risk frequency in the historical record data.

[0014] Optionally, the oscillation risk assessment module is specifically used to: obtain the difference between the frequency of the sub / supersynchronous oscillation interharmonic and the torsional vibration frequency; when the difference is less than a preset difference threshold, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonic is the highest level oscillation risk; when the difference is not less than the preset difference threshold, determine whether there is an oscillation risk frequency with the same frequency as the sub / supersynchronous oscillation interharmonic among each oscillation risk frequency; when there is no oscillation risk frequency with the same frequency as the sub / supersynchronous oscillation interharmonic, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonic is the occurrence of a new oscillation risk; when there is an oscillation risk frequency with the same frequency as the sub / supersynchronous oscillation interharmonic, use the same oscillation risk frequency as the target oscillation risk frequency; according to the amplitude threshold of the target oscillation risk frequency, obtain the amplitude assessment threshold value of the sub / supersynchronous oscillation interharmonic, and obtain the oscillation risk assessment of the sub / supersynchronous oscillation interharmonic through the following assessment logic Results: When conditions 1, 2 and 3 are met, the oscillation risk assessment result is a first-level oscillation risk; when condition 2 or condition 2 and condition 3 are met, the oscillation risk assessment result is a second-level oscillation risk; when conditions 1, 1 and 2 or condition 1 and condition 3 are met, the oscillation risk assessment result is a third-level oscillation risk; when only condition 3 is met, the oscillation risk assessment result is a fourth-level oscillation risk; when conditions 1, 2 and 3 are not met, the oscillation risk assessment result is no risk warning; among them, condition 1: the amplitude of the sub / supersynchronous oscillation interharmonic is greater than the amplitude assessment threshold value, and the duration is greater than the first preset time threshold; condition 2: the amplitude of the sub / supersynchronous oscillation interharmonic continues to amplify for a time greater than the second preset time threshold; condition 3: the sign of the cosθ value of the sub / supersynchronous oscillation interharmonic is consistent with the sign of the bus flowing into it, and the duration is greater than the third preset time threshold; among them, θ is the voltage and current angle difference.

[0015] In a third aspect of the present invention, a computer device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned power system oscillation risk assessment method when executing the computer program.

[0016] According to a fourth aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above-mentioned power system oscillation risk assessment method are implemented.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The power system oscillation risk assessment method of the present invention obtains measurement data from the monitored power system to obtain the frequency, amplitude, and voltage / current angle difference of the sub / supersynchronous interharmonics in real time when sub / supersynchronous interharmonics are present. The method then evaluates the sub / supersynchronous interharmonics by combining the torsional vibration frequency, various oscillation risk frequencies, and amplitude thresholds of each oscillation risk frequency in the historical data to obtain an oscillation risk assessment result. Simultaneously, the frequency and amplitude of the sub / supersynchronous interharmonics with oscillation risk are added to the historical data, enabling dynamic updating of the torsional vibration frequency, various oscillation risk frequencies, and amplitude thresholds of each oscillation risk frequency in the historical data to assist in the next oscillation risk assessment. By combining the historical data with real-time data for oscillation risk assessment and continuously optimizing the historical data with real-time data, the method eliminates the problem of inaccurate assessment results caused by changes in the resonance point due to changes in the power system operating mode, compared to current offline methods of obtaining impedance through frequency sweeping or resonant point frequency through modeling. This method can effectively improve the accuracy of oscillation risk assessment results and reduce the false alarm rate of oscillation risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of a method for assessing power system oscillation risk according to an embodiment of the present invention.

[0020] Figure 2 This is a structural block diagram of a power system oscillation risk assessment system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0022] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0023] The present invention is described in further detail below with reference to the accompanying drawings:

[0024] See also Figure 1 In one embodiment of the present invention, a method for assessing the risk of power system oscillations is provided. This method combines historical record data with real-time measurement data to perform oscillation risk assessment. Compared with existing offline assessment methods, this method can effectively improve the accuracy of the assessment results and avoid false alarms. Specifically, the method for assessing the risk of power system oscillations includes the following steps:

[0025] S1: Monitor the measurement data of the power system in real time, and determine whether there are sub-synchronous / super-synchronous oscillation interharmonics in the power system based on the measurement data; and when sub-synchronous / super-synchronous oscillation interharmonics exist in the power system, obtain the frequency, amplitude, and voltage-current angle difference of the sub-synchronous / super-synchronous oscillation interharmonics.

[0026] S2: Based on the frequency, amplitude, and voltage-current angle difference of the subsynchronous / supersynchronous oscillation interharmonics, and combined with the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical data, data trend calculation and logical judgment are performed to obtain the oscillation risk assessment results of the subsynchronous / supersynchronous oscillation interharmonics.

[0027] S3: Add the frequency and amplitude of the sub / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment results to the historical record data, and update the torsional vibration frequency, each oscillation risk frequency and the amplitude threshold of each oscillation risk frequency in the historical record data.

[0028] In summary, the power system oscillation risk assessment method of the present invention obtains measurement data from the monitored power system to obtain the frequency, amplitude, and voltage-current angle difference of the sub- / super-synchronous interharmonics in real time when sub- / super-synchronous interharmonics are present. The frequency and amplitude of the sub- / super-synchronous interharmonics presenting oscillation risk are then combined with the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data to evaluate the sub- / super-synchronous interharmonics and obtain an oscillation risk assessment result. Simultaneously, the frequency and amplitude of the sub- / super-synchronous interharmonics presenting oscillation risk are added to the historical record data to dynamically update the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data to assist in the next oscillation risk assessment. By combining the historical record data with real-time data for oscillation risk assessment and continuously optimizing the historical record data with real-time data, compared to the current offline method of obtaining impedance through frequency sweeping or obtaining the resonance point frequency through modeling, the method eliminates the situation in which the resonance point changes caused by changes in the power system operating mode, thereby effectively improving the accuracy of the oscillation risk assessment results and reducing the false alarm rate of oscillation risk.

[0029] In one possible implementation, real-time monitoring of power system measurement data is typically achieved using a broadband measurement device. This device can measure electrical quantities in the power system over a wide frequency range of 0 to 2500 Hz, promptly capturing sub- and super-synchronous interharmonic signals in voltage and current. Specifically, sub- and super-synchronous frequencies are defined as 2.5 to 45 Hz and 55 to 97.5 Hz.

[0030] Specifically, determining whether subsynchronous / supersynchronous interharmonics exist in the power system based on the measured data includes: obtaining voltage or current in the measured data; obtaining interharmonic spectrum components of the voltage or current using a spectrum analysis algorithm; determining that subsynchronous / supersynchronous interharmonics exist in the power system when the interharmonic spectrum components of the voltage or current are greater than a dead zone in the power system; otherwise, determining that subsynchronous / supersynchronous interharmonics do not exist in the power system. The spectrum analysis algorithm may be a fast Fourier transform algorithm or a Prony algorithm.

[0031] In one possible embodiment, when sub / super synchronous oscillation interharmonics exist in the power system, obtaining the frequency, amplitude, and voltage / current angle difference of the sub / super synchronous oscillation interharmonics includes: obtaining each interharmonic of the voltage or current excluding the fundamental wave; sorting the interharmonics in descending order of amplitude, and using the top N interharmonics in the sorting as the sub / super synchronous oscillation interharmonics for evaluation; wherein N is a preset constant; and obtaining the frequency, amplitude, and voltage / current angle difference of each sub / super synchronous oscillation interharmonic.

[0032] Specifically, the interharmonics are screened according to their amplitudes, and the dominant components among all interharmonics are selected and used as sub / supersynchronous oscillation interharmonics for subsequent analysis, thereby avoiding the influence of small-amplitude interharmonics, speeding up the oscillation risk assessment, and effectively preventing frequent warnings.

[0033] In a possible embodiment, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is obtained by performing data trend calculation and logical judgment based on the frequency, amplitude, and voltage-current angle difference of the sub / supersynchronous oscillation interharmonics, and in combination with the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data, including: obtaining the difference between the frequency of the sub / supersynchronous oscillation interharmonics and the torsional vibration frequency; when the difference is less than a preset difference threshold, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is the highest level oscillation risk; when the difference is not less than the preset difference threshold, determining whether there is an oscillation risk frequency with the same frequency as the sub / supersynchronous oscillation interharmonics among the oscillation risk frequencies; when there is no oscillation risk frequency with the same frequency as the sub / supersynchronous oscillation interharmonics, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is the presence of New oscillation risk; when there is an oscillation risk frequency that is the same as the frequency of the sub / supersynchronous oscillation interharmonic, the same oscillation risk frequency is used as the target oscillation risk frequency; according to the amplitude threshold of the target oscillation risk frequency, the amplitude assessment threshold value of the sub / supersynchronous oscillation interharmonic is obtained, and the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonic is obtained through the following assessment logic: when conditions 1, 2 and 3 are met, the oscillation risk assessment result is a first-level oscillation risk; when condition 2 or condition 2 and condition 3 are met, the oscillation risk assessment result is a second-level oscillation risk; when conditions 1, 1 and 2 or condition 1 and 3 are met, the oscillation risk assessment result is a third-level oscillation risk; when only condition 3 is met, the oscillation risk assessment result is a fourth-level oscillation risk; when conditions 1, 2 and 3 are not met, the oscillation risk assessment result is no risk warning.

[0034] Among them, condition 1: the amplitude of the sub / supersynchronous oscillation interharmonic is greater than the amplitude assessment threshold value, and the duration is greater than the first preset time threshold; condition 2: the amplitude of the sub / supersynchronous oscillation interharmonic continues to amplify for a time greater than the second preset time threshold; condition 3: the sign of the cosθ value of the sub / supersynchronous oscillation interharmonic is consistent with the sign of the inflow bus, and the duration is greater than the third preset time threshold; wherein θ is the voltage and current angle difference.

[0035] Specifically, when conducting an oscillation risk assessment of sub / supersynchronous oscillation interharmonics, the torsional vibration risk is considered first, because after the torsional vibration risk occurs, the subsequent impact is wide-ranging and deep-going. Therefore, the difference between the frequency of the sub / supersynchronous oscillation interharmonics and the torsional vibration frequency is first obtained, and then it is determined whether the difference is less than the preset difference threshold to determine whether a torsional vibration risk has occurred. The torsional vibration frequency of the generator shaft system of the surrounding power plants is fully considered, and the risk assessment logic is optimized for this, independent of other judgment logics, so as to promptly discover the risk of torsional vibration of the generators of the surrounding power plants. Among them, the preset difference threshold is generally based on the actual topology of the power system and is set according to manual experience. Optionally, when the torsional vibration frequency is initialized, it can be set to the complementary frequency of the torsional vibration frequency of the generator shaft system within the preset range of the power system.

[0036] Specifically, when the difference is not less than a preset difference threshold, it is determined whether the frequency of the current sub- / super-synchronous interharmonic exists in the historical record data. If the frequency of the current sub- / super-synchronous interharmonic does not exist in the historical record data, that is, there is no oscillation risk frequency identical to the frequency of the sub- / super-synchronous interharmonic among the oscillation risk frequencies, then it is considered that a new interharmonic has appeared, and the oscillation risk assessment result for the current sub- / super-synchronous interharmonic is directly given, i.e., a new oscillation risk has appeared.

[0037] If the frequency of the current sub / supersynchronous interharmonic is present in the historical data, that is, if there is an oscillation risk frequency identical to the frequency of the sub / supersynchronous interharmonic among the oscillation risk frequencies, then the same oscillation risk frequency is first used as the target oscillation risk frequency. A specific oscillation risk assessment is then performed based on the preset oscillation risk assessment logic. The amplitude assessment threshold for the sub / supersynchronous interharmonic is derived based on the amplitude threshold of the target oscillation risk frequency. This target oscillation risk frequency amplitude threshold can then be used directly as the amplitude assessment threshold for the current sub / supersynchronous interharmonic.

[0038] In this embodiment, the oscillation risk assessment logic is as follows: when conditions 1, 2, and 3 are met, the oscillation risk assessment result is a first-level oscillation risk; when condition 2, or conditions 2 and 3 are met, the oscillation risk assessment result is a second-level oscillation risk; when conditions 1, 1, and 2, or conditions 1 and 3 are met, the oscillation risk assessment result is a third-level oscillation risk; when only condition 3 is met, the oscillation risk assessment result is a fourth-level oscillation risk; and when conditions 1, 2, and 3 are all unmet, the oscillation risk assessment result is no risk warning. This oscillation risk assessment logic fully considers the amplitude, amplitude variation, and impedance of the subsynchronous / supersynchronous oscillation interharmonics, and adopts a judgment logic that combines these three factors to ensure the accuracy of the assessment results. At the same time, a hierarchical method is used for oscillation risk assessment to fully characterize the oscillation risk situation.

[0039] In addition, the above-mentioned oscillation risk assessment process also adopts a progressive assessment logic, that is, when the frequency of sub / supersynchronous oscillation interharmonics appears for the first time, the assessment result is given directly; when it appears again subsequently, the oscillation risk assessment logic judgment combined with the historical record data is carried out. This ensures that the sub / supersynchronous oscillation interharmonic risk situation that appears for the first time is promptly informed to the control personnel, and a judgment is made based on subsequent developments.

[0040] Optionally, the historical data is historical data under the current load level of the power system. Specifically, 10% can be used as the boundary between different load levels. By further refining the feature granularity based on the load level, it is helpful to statistically analyze the operating regularity characteristics and further improve the accuracy of the oscillation risk assessment results.

[0041] In a possible embodiment, the frequency and amplitude of the sub / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment result are added to the historical record data, and the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data are updated, including: obtaining the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency, and taking the average of the torsional vibration frequency and the frequency of the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency as the new torsional vibration frequency; traversing each oscillation risk frequency: obtaining the target sub / supersynchronous oscillation interharmonic of the current oscillation risk frequency, and taking the amplitude threshold of the current oscillation risk .... The average of the amplitudes of the target sub / supersynchronous interharmonics of the current oscillation risk frequency is used as the new amplitude threshold of the current oscillation risk frequency; the target sub / supersynchronous interharmonics of the torsional vibration frequency and the target sub / supersynchronous interharmonics of each oscillation risk frequency in the sub / supersynchronous interharmonics are eliminated to obtain the remaining sub / supersynchronous interharmonics; and when the remaining sub / supersynchronous interharmonics are not empty, each remaining sub / supersynchronous interharmonic is traversed: the current remaining sub / supersynchronous interharmonic is used as the oscillation risk frequency, and the amplitude of the current remaining sub / supersynchronous interharmonic is used as the amplitude threshold of the current oscillation risk frequency.

[0042] Among them, the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with the torsional vibration frequency less than a first preset difference threshold; the target sub / supersynchronous oscillation interharmonic of each oscillation risk frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with each oscillation risk frequency less than a second preset threshold.

[0043] Specifically, after obtaining the oscillation risk assessment results of each sub / supersynchronous oscillation interharmonic, the frequency and amplitude of the sub / supersynchronous oscillation interharmonic with oscillation risk are obtained, and based on this, the data in the historical record data is modified to ensure that the historical record data can change dynamically to be close to the real-time operation of the power system.

[0044] Among them, the average of the torsional vibration frequency and the frequency of the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency is used as the new torsional vibration frequency, and the average of the amplitude threshold of the current oscillation risk frequency and the amplitude of the target sub / supersynchronous oscillation interharmonic of the current oscillation risk frequency is used as the new amplitude threshold of the current oscillation risk frequency. Both are updated from an averaging perspective, and the average frequency or average amplitude is used as the next judgment threshold, which can effectively adapt to the real-time situation of the power system, thereby optimizing the evaluation logic and effectively avoiding frequent early warnings and false alarms.

[0045] In a possible embodiment, the power system oscillation risk assessment method further includes: obtaining and recording the duration of sub / super synchronous oscillation interharmonics with oscillation risk, the final form of oscillation, and the long recording data within the duration of sub / super synchronous oscillation interharmonics in the oscillation risk assessment results.

[0046] Specifically, by recording relevant information about subsynchronous / supersynchronous oscillation interharmonics that pose an oscillation risk, such as duration, final oscillation form, and long-duration waveform data within the duration of the subsynchronous / supersynchronous oscillation interharmonics, it facilitates in-depth analysis of subsequent oscillation risks and can also set different oscillation risk suppression strategies for different levels of oscillation risk assessment results. For example, when a subsynchronous / supersynchronous oscillation risk exists, the power system's output level is first calculated and determined. If the output level falls below a certain set value, the generator is disconnected; grid connection is then resumed after the subsynchronous / supersynchronous oscillation risk disappears.

[0047] The following are device embodiments of the present invention, which can be used to implement the method embodiments of the present invention. For details not disclosed in the device embodiments, please refer to the method embodiments of the present invention.

[0048] See also Figure 2 In another embodiment of the present invention, a power system oscillation risk assessment system is provided, which can be used to implement the above-mentioned power system oscillation risk assessment method. Specifically, the power system oscillation risk assessment system includes a data acquisition module, an oscillation risk assessment module and a data update module.

[0049] Among them, the data acquisition module is used to monitor the measurement data of the power system in real time, and determine whether there are sub / supersynchronous oscillation interharmonics in the power system based on the measurement data; and when there are sub / supersynchronous oscillation interharmonics in the power system, obtain the frequency, amplitude and voltage-current angle difference of the sub / supersynchronous oscillation interharmonics; the oscillation risk assessment module is used to perform data trend calculation and logical judgment based on the frequency, amplitude and voltage-current angle difference of the sub / supersynchronous oscillation interharmonics, and combined with the torsional vibration frequency, each oscillation risk frequency and the amplitude threshold of each oscillation risk frequency in the historical record data to obtain the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics; the data update module is used to add the frequency and amplitude of the sub / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment result to the historical record data, and update the torsional vibration frequency, each oscillation risk frequency and the amplitude threshold of each oscillation risk frequency in the historical record data.

[0050] In one possible embodiment, when sub / super synchronous oscillation interharmonics exist in the power system, obtaining the frequency, amplitude, and voltage / current angle difference of the sub / super synchronous oscillation interharmonics includes: obtaining each interharmonic of the voltage or current excluding the fundamental wave; sorting the interharmonics in descending order of amplitude, and using the top N interharmonics in the sorting as the sub / super synchronous oscillation interharmonics for evaluation; wherein N is a preset constant; and obtaining the frequency, amplitude, and voltage / current angle difference of each sub / super synchronous oscillation interharmonic.

[0051] In a possible embodiment, the oscillation risk assessment module is specifically used to: obtain the difference between the frequency of the sub / supersynchronous oscillation interharmonic and the torsional vibration frequency; when the difference is less than a preset difference threshold, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonic is the highest level oscillation risk; when the difference is not less than the preset difference threshold, determine whether there is an oscillation risk frequency that is the same as the frequency of the sub / supersynchronous oscillation interharmonic among the oscillation risk frequencies; when there is no oscillation risk frequency that is the same as the frequency of the sub / supersynchronous oscillation interharmonic, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonic is the occurrence of a new oscillation risk; when there is an oscillation risk frequency that is the same as the frequency of the sub / supersynchronous oscillation interharmonic, the same oscillation risk frequency is considered as the occurrence of a new oscillation risk. is the target oscillation risk frequency; according to the amplitude threshold of the target oscillation risk frequency, the amplitude assessment threshold value of the sub / supersynchronous oscillation interharmonics is obtained, and the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is obtained through the following assessment logic: when conditions 1, 2 and 3 are met, the oscillation risk assessment result is a first-level oscillation risk; when condition 2 or condition 2 and condition 3 are met, the oscillation risk assessment result is a second-level oscillation risk; when conditions 1, 1 and 2 or condition 1 and 3 are met, the oscillation risk assessment result is a third-level oscillation risk; when only condition 3 is met, the oscillation risk assessment result is a fourth-level oscillation risk; when conditions 1, 2 and 3 are not met, the oscillation risk assessment result is no risk warning.

[0052] Among them, condition 1: the amplitude of the sub / supersynchronous oscillation interharmonic is greater than the amplitude assessment threshold value, and the duration is greater than the first preset time threshold; condition 2: the amplitude of the sub / supersynchronous oscillation interharmonic continues to amplify for a time greater than the second preset time threshold; condition 3: the sign of the cosθ value of the sub / supersynchronous oscillation interharmonic is consistent with the sign of the inflow bus, and the duration is greater than the third preset time threshold; wherein θ is the voltage and current angle difference.

[0053] In one possible implementation, the data update module is specifically configured to: obtain a target sub- / super-synchronous interharmonic of the torsional vibration frequency, and use the average of the torsional vibration frequency and the frequency of the target sub- / super-synchronous interharmonic of the torsional vibration frequency as the new torsional vibration frequency; traverse each oscillation risk frequency: obtain a target sub- / super-synchronous interharmonic of the current oscillation risk frequency, and use the average of the amplitude threshold of the current oscillation risk frequency and the amplitude of the target sub- / super-synchronous interharmonic of the current oscillation risk frequency as the new amplitude threshold of the current oscillation risk frequency; eliminate the target sub- / super-synchronous interharmonic of the torsional vibration frequency and the target sub- / super-synchronous interharmonic of each oscillation risk frequency from the sub- / super-synchronous interharmonic to obtain the remaining sub- / super-synchronous interharmonics; and when the remaining sub- / super-synchronous interharmonics is not empty, traverse each remaining sub- / super-synchronous interharmonic: use the current remaining sub- / super-synchronous interharmonic as the oscillation risk frequency, and use the amplitude of the current remaining sub- / super-synchronous interharmonic as the amplitude threshold of the current oscillation risk frequency.

[0054] Among them, the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with the torsional vibration frequency less than a first preset difference threshold; the target sub / supersynchronous oscillation interharmonic of each oscillation risk frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with each oscillation risk frequency less than a second preset threshold.

[0055] In a possible implementation, the torsional vibration frequency is set to the complementary frequency of the torsional vibration frequency of the generator shaft system within a preset range of the power system during initialization; and the historical record data is historical record data under the current load level of the power system.

[0056] In a possible embodiment, a data recording module is further included to obtain and record the duration of sub / supersynchronous oscillation interharmonics with oscillation risk, the final form of oscillation, and the long-wave recording data within the duration of sub / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment results.

[0057] All relevant contents of each step involved in the embodiment of the aforementioned power system oscillation risk assessment method can be referred to the functional description of the corresponding functional modules of the power system oscillation risk assessment system in the embodiment of the present invention, and will not be repeated here.

[0058] The module division in the embodiments of the present invention is illustrative and represents only one logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional modules in various embodiments of the present invention may be integrated into a single processor, exist physically as separate modules, or two or more modules may be integrated into a single module. The integrated modules may be implemented in either hardware or software functional modules.

[0059] In another embodiment of the present invention, a computer device is provided, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function; the processor described in the embodiment of the present invention can be used for the operation of the power system oscillation risk assessment method.

[0060] In another embodiment of the present invention, a storage medium is provided, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a computer device, used to store programs and data. It is understood that the computer-readable storage medium herein may include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides storage space, which stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for being loaded and executed by a processor. These instructions may be one or more computer programs (including program code). It should be noted that the computer-readable storage medium herein may be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage device. The processor may load and execute the one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the power system oscillation risk assessment method described in the above embodiment.

[0061] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0062] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0063] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0064] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for assessing power system oscillation risk, characterized in that: include: Monitor the measurement data of the power system in real time and determine whether there are sub-synchronous / super-synchronous oscillation interharmonics in the power system based on the measurement data; and when sub / super synchronous oscillation interharmonics exist in the power system, obtaining the frequency, amplitude, and voltage / current angle difference of the sub / super synchronous oscillation interharmonics; Based on the frequency, amplitude, and voltage-current angle difference of the subsynchronous / supersynchronous oscillation interharmonics, and combined with the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical data, data trend calculation and logical judgment are performed to obtain the oscillation risk assessment results of the subsynchronous / supersynchronous oscillation interharmonics; The frequencies and amplitudes of the subsynchronous / supersynchronous oscillation interharmonics with oscillation risks in the oscillation risk assessment results are added to the historical record data, and the torsional vibration frequencies, the oscillation risk frequencies, and the amplitude thresholds of the oscillation risk frequencies in the historical record data are updated; The method of adding the frequency and amplitude of the subsynchronous / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment result to the historical record data, and updating the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data includes: Obtaining a target subharmonic / supersynchronous oscillation interharmonic of the torsional vibration frequency, and taking an average of the torsional vibration frequency and the frequency of the target subharmonic / supersynchronous oscillation interharmonic of the torsional vibration frequency as a new torsional vibration frequency; Traverse each oscillation risk frequency: obtain the target sub- / supersynchronous oscillation interharmonic of the current oscillation risk frequency, and use the average of the amplitude threshold of the current oscillation risk frequency and the amplitude of the target sub- / supersynchronous oscillation interharmonic of the current oscillation risk frequency as the new amplitude threshold of the current oscillation risk frequency; Eliminating the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency and the target sub / supersynchronous oscillation interharmonic of each oscillation risk frequency from the sub / supersynchronous oscillation interharmonics to obtain the remaining sub / supersynchronous oscillation interharmonics; and when the remaining sub / supersynchronous oscillation interharmonics are not empty, traversing each remaining sub / supersynchronous oscillation interharmonic: using the current remaining sub / supersynchronous oscillation interharmonic as the oscillation risk frequency, and using the amplitude of the current remaining sub / supersynchronous oscillation interharmonic as the amplitude threshold of the current oscillation risk frequency; Among them, the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with the torsional vibration frequency less than a first preset difference threshold; the target sub / supersynchronous oscillation interharmonic of each oscillation risk frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with each oscillation risk frequency less than a second preset threshold.

2. The power system oscillation risk assessment method according to claim 1, characterized in that: When subsynchronous / supersynchronous oscillation interharmonics exist in the power system, obtaining the frequency, amplitude, and voltage / current angle difference of the subsynchronous / supersynchronous oscillation interharmonics includes: Obtain the interharmonics of voltage or current except the fundamental wave; Sort the interharmonics in descending order of amplitude, and use the top N interharmonics as subsynchronous / supersynchronous oscillation interharmonics for evaluation; where N is a preset constant; Obtain the frequency, amplitude, and voltage and current angle difference of each sub / supersynchronous oscillation interharmonic.

3. The power system oscillation risk assessment method according to claim 1, characterized in that: The oscillation risk assessment results of sub / supersynchronous oscillation interharmonics are obtained by performing data trend calculation and logical judgment based on the frequency, amplitude, and voltage / current angle difference of the sub / supersynchronous oscillation interharmonics, and combining the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data, including: Obtaining the difference between the frequency of the sub / supersynchronous oscillation interharmonic and the torsional vibration frequency; When the difference is less than the preset difference threshold, the oscillation risk assessment result of the subsynchronous / supersynchronous oscillation interharmonic is the highest level oscillation risk; when the difference is not less than the preset difference threshold, it is determined whether there is an oscillation risk frequency in each oscillation risk frequency that is the same as the frequency of the subsynchronous / supersynchronous oscillation interharmonic; When there is no oscillation risk frequency identical to the frequency of the sub / supersynchronous oscillation interharmonic, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonic is the emergence of a new oscillation risk; when there is an oscillation risk frequency identical to the frequency of the sub / supersynchronous oscillation interharmonic, the identical oscillation risk frequency is used as the target oscillation risk frequency. According to the amplitude threshold of the target oscillation risk frequency, the amplitude assessment threshold of the sub / supersynchronous oscillation interharmonics is obtained, and the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is obtained through the following assessment logic: When conditions 1, 2, and 3 are met, the oscillation risk assessment result is a first-level oscillation risk; when condition 2 or condition 2 and 3 are met, the oscillation risk assessment result is a second-level oscillation risk; when conditions 1, 1, and 2 or condition 1 and 3 are met, the oscillation risk assessment result is a third-level oscillation risk; when only condition 3 is met, the oscillation risk assessment result is a fourth-level oscillation risk; when conditions 1, 2, and 3 are all unmet, the oscillation risk assessment result is no risk warning; Among them, condition 1: the amplitude of the sub / supersynchronous oscillation interharmonic is greater than the amplitude assessment threshold value, and the duration is greater than the first preset time threshold; condition 2: the amplitude of the sub / supersynchronous oscillation interharmonic continues to amplify for a time greater than the second preset time threshold; condition 3: the sign of the cosθ value of the sub / supersynchronous oscillation interharmonic is consistent with the sign of the inflow bus, and the duration is greater than the third preset time threshold; wherein θ is the voltage and current angle difference.

4. The power system oscillation risk assessment method according to claim 1, characterized in that: The torsional vibration frequency is set to the complementary frequency of the torsional vibration frequency of the generator shaft system within the preset range of the power system during initialization; the historical record data is the historical record data under the current load level of the power system.

5. The power system oscillation risk assessment method according to claim 1, characterized in that: Also includes: Obtain and record the duration of sub / supersynchronous oscillation interharmonics with oscillation risk, the final oscillation form, and the long-wave recording data within the duration of sub / supersynchronous oscillation interharmonics in the oscillation risk assessment results.

6. A power system oscillation risk assessment system, characterized in that: include: A data acquisition module is used to monitor the measurement data of the power system in real time and determine whether there are subsynchronous / supersynchronous oscillation interharmonics in the power system based on the measurement data; and when sub / super synchronous oscillation interharmonics exist in the power system, obtaining the frequency, amplitude, and voltage / current angle difference of the sub / super synchronous oscillation interharmonics; The oscillation risk assessment module is used to calculate the frequency, amplitude, and voltage-current angle difference of the subsynchronous / supersynchronous oscillation interharmonics, and to combine the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data to perform data trend calculation and logical judgment to obtain the oscillation risk assessment result of the subsynchronous / supersynchronous oscillation interharmonics; A data update module is used to add the frequency and amplitude of the subsynchronous / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment results to the historical record data, and to update the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data; The method of adding the frequency and amplitude of the subsynchronous / supersynchronous oscillation interharmonics with oscillation risk in the oscillation risk assessment result to the historical record data, and updating the torsional vibration frequency, each oscillation risk frequency, and the amplitude threshold of each oscillation risk frequency in the historical record data includes: Obtaining a target subharmonic / supersynchronous oscillation interharmonic of the torsional vibration frequency, and taking an average of the torsional vibration frequency and the frequency of the target subharmonic / supersynchronous oscillation interharmonic of the torsional vibration frequency as a new torsional vibration frequency; Traverse each oscillation risk frequency: obtain the target sub- / supersynchronous oscillation interharmonic of the current oscillation risk frequency, and use the average of the amplitude threshold of the current oscillation risk frequency and the amplitude of the target sub- / supersynchronous oscillation interharmonic of the current oscillation risk frequency as the new amplitude threshold of the current oscillation risk frequency; Eliminating the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency and the target sub / supersynchronous oscillation interharmonic of each oscillation risk frequency from the sub / supersynchronous oscillation interharmonics to obtain the remaining sub / supersynchronous oscillation interharmonics; and when the remaining sub / supersynchronous oscillation interharmonics are not empty, traversing each remaining sub / supersynchronous oscillation interharmonic: using the current remaining sub / supersynchronous oscillation interharmonic as the oscillation risk frequency, and using the amplitude of the current remaining sub / supersynchronous oscillation interharmonic as the amplitude threshold of the current oscillation risk frequency; Among them, the target sub / supersynchronous oscillation interharmonic of the torsional vibration frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with the torsional vibration frequency less than a first preset difference threshold; the target sub / supersynchronous oscillation interharmonic of each oscillation risk frequency is the sub / supersynchronous oscillation interharmonic whose frequency has a difference with each oscillation risk frequency less than a second preset threshold.

7. The power system oscillation risk assessment system according to claim 6, characterized in that: The oscillation risk assessment module is specifically used to: Obtaining the difference between the frequency of the sub / supersynchronous oscillation interharmonic and the torsional vibration frequency; When the difference is less than the preset difference threshold, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonic is the highest level oscillation risk; When the difference is not less than a preset difference threshold, determining whether there is an oscillation risk frequency in each oscillation risk frequency that is the same as the frequency of the subsynchronous / supersynchronous oscillation interharmonic; When there is no oscillation risk frequency identical to the frequency of the sub / supersynchronous oscillation interharmonic, the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonic is the emergence of a new oscillation risk; when there is an oscillation risk frequency identical to the frequency of the sub / supersynchronous oscillation interharmonic, the identical oscillation risk frequency is used as the target oscillation risk frequency. According to the amplitude threshold of the target oscillation risk frequency, the amplitude assessment threshold of the sub / supersynchronous oscillation interharmonics is obtained, and the oscillation risk assessment result of the sub / supersynchronous oscillation interharmonics is obtained through the following assessment logic: When conditions 1, 2, and 3 are met, the oscillation risk assessment result is level 1 oscillation risk; When condition 2 or condition 2 and condition 3 are met, the oscillation risk assessment result is level 2 oscillation risk; When condition 1, condition 1 and condition 2, or condition 1 and condition 3 are met, the oscillation risk assessment result is level 3 oscillation risk; When only condition 3 is met, the oscillation risk assessment result is level 4 oscillation risk; When conditions 1, 2, and 3 are all unsatisfied, the oscillation risk assessment result is no risk warning; Among them, condition 1: the amplitude of the sub / supersynchronous oscillation interharmonic is greater than the amplitude assessment threshold value, and the duration is greater than the first preset time threshold; condition 2: the amplitude of the sub / supersynchronous oscillation interharmonic continues to amplify for a time greater than the second preset time threshold; condition 3: the sign of the cosθ value of the sub / supersynchronous oscillation interharmonic is consistent with the sign of the inflow bus, and the duration is greater than the third preset time threshold; wherein θ is the voltage and current angle difference.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the power system oscillation risk assessment method according to any one of claims 1 to 5 are implemented.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the power system oscillation risk assessment method according to any one of claims 1 to 5 are implemented.

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