A power system stability determination method, device, equipment and storage medium

Abstract

The application provides a power system stability determination method, device and equipment and a storage medium, is applied to the energy storage technical field, and the method comprises the following steps: constructing a power system stability determination model; obtaining a first parameter value, a second parameter value, a third parameter value and a fourth parameter value; solving the power system stability determination model according to the first parameter value, the second parameter value, the third parameter value and the fourth parameter value, determining a target energy storage installed capacity and a target energy storage duration of a new energy station; and determining the power system stability of the new energy station according to the target energy storage installed capacity and the target energy storage duration. The method constructs a power system stability determination model comprising a target function and constraint conditions for maximizing the income of a new energy station, determines the target energy storage installed capacity and the target energy storage duration of the new energy station, optimally configures the energy storage from the comprehensive perspective of the system and the new energy station, and improves the new energy utilization rate.

Description

Technical Field

[0001] This application relates to the field of stability determination, and in particular to a method, apparatus, equipment and storage medium for determining the stability of a power system. Background Technology

[0002] The maximum value of the Rate of Change of Frequency (RoCoF) under power disturbances is one of the important indicators for judging the frequency stability of a power system. Existing technologies analyze the maximum rate of change of frequency by constructing analytical models of the frequency response of "high-energy-consuming and high-distribution" power systems that include power generation equipment such as new energy sources, energy storage, and synchronous generators. However, existing frequency response models only analyze the system frequency change characteristics caused by a given active power disturbance, ignoring the influence of other factors, resulting in low accuracy in judging the support capacity and stability of the power system. Summary of the Invention

[0003] This application provides a method, apparatus, device, and storage medium for determining the stability of a power system, in order to solve the problem of low utilization rate of new energy sources in existing methods for determining the stability of a power system.

[0004] To solve the above-mentioned technical problems, this application is implemented as follows:

[0005] In a first aspect, embodiments of this application provide a method for determining the stability of a power system. The method includes:

[0006] When the power system receives a disturbance signal, the voltage increment and current increment of the power system, which includes converters and synchronous generators, are collected.

[0007] The maximum rate of change of frequency under power disturbance is determined based on the voltage increment, current increment, and objective function. The maximum rate of change of frequency under power disturbance is used to determine the stability of the power system.

[0008] The objective function is a function that aims to maximize the rate of change of frequency of the power system under power disturbance. The objective function is constructed based on the active oscillation mode frequency, the phase angle oscillation parameters of the converter port voltage, and the synchronous generator parameters. The active oscillation mode frequency is the power fluctuation frequency under the low-frequency oscillation phenomenon caused by the grid connection of the converter in the power system.

[0009] Optionally, the converter port voltage phase angle oscillation parameters include oscillation amplitude and initial phase; and / or,

[0010] The synchronous generator parameters include the synchronous generator output electromagnetic power, the synchronous generator power angle, the rotor inertia time constant, and the damping coefficient.

[0011] Optionally, the objective function is:

[0012]

[0013] P e =k1Δδ SG -k2Δθ inv

[0014] ω f =2πf P

[0015] Where M is the rotor inertia time constant, D is the damping coefficient, and Δθ inv σ is the disturbance of the phase angle of the converter output voltage. SSO Where A is the damping coefficient, A1 is the oscillation amplitude, and θ is the damping coefficient. inv δ is the phase angle of the converter output voltage. SG P represents the power angle of the synchronous generator power supply. e f represents the electromagnetic power output of the synchronous generator. P Indicates the frequency of the active oscillation mode. Indicates the initial phase.

[0016] Optionally, determining the maximum rate of change of frequency under power disturbance based on the voltage increment, current increment, and objective function includes:

[0017] The equivalent reactance curve and equivalent resistance curve of the power system are determined by an impedance identification algorithm based on the voltage and current increments.

[0018] The active power oscillation mode frequency, converter port voltage phase angle oscillation parameters, and synchronous generator parameters are determined based on the equivalent reactance curve and the equivalent resistance curve.

[0019] The maximum rate of change of frequency under power disturbance is determined based on the active oscillation mode frequency, converter port voltage phase angle oscillation parameters, synchronous generator parameters, and objective function.

[0020] Optionally, after determining the equivalent reactance curve and equivalent resistance curve of the power system using the impedance identification algorithm based on the voltage increment and current increment, the method further includes:

[0021] If the first condition is met, the power system is determined to be in a weakly damped state; wherein the first condition includes:

[0022] At least one of the equivalent reactance curve and the equivalent resistance curve has a zero-crossing point, and the frequency value of the zero-crossing point is within a first range, while the absolute value of the curve slope at the zero-crossing point is within a second range.

[0023] The frequency of the active oscillation mode is:

[0024] f P =50-f r

[0025] Among them, f P f represents the frequency of the active oscillation mode. r The frequency of at least one zero-crossing point in the equivalent reactance curve and the equivalent resistance curve.

[0026] Secondly, embodiments of this application also provide a power system stability determination device. This power system stability determination device includes:

[0027] The acquisition module is used to acquire the voltage increment and current increment of the power system, which includes converters and synchronous generators, when the power system receives a disturbance signal.

[0028] The determination module is used to determine the maximum rate of change of frequency under power disturbance based on the voltage increment, current increment and objective function, wherein the maximum rate of change of frequency under power disturbance is used to determine the stability of the power system;

[0029] The objective function is a function that aims to maximize the rate of change of frequency of the power system under power disturbance. The objective function is constructed based on the active oscillation mode frequency, the phase angle oscillation parameters of the converter port voltage, and the synchronous generator parameters. The active oscillation mode frequency is the power fluctuation frequency under the low-frequency oscillation phenomenon caused by the grid connection of the converter in the power system.

[0030] Optionally, the converter port voltage phase angle oscillation parameters include oscillation amplitude and initial phase; and / or,

[0031] The synchronous generator parameters include the synchronous generator output electromagnetic power, the synchronous generator power angle, the rotor inertia time constant, and the damping coefficient.

[0032] Optionally, the objective function includes:

[0033]

[0034] P e =k1Δδ SG -k2Δθ inv

[0035] ω f =2πf P

[0036] Where M is the rotor inertia time constant, D is the damping coefficient, and Δθ inv σ is the disturbance of the phase angle of the converter output voltage. SSO Where A is the damping coefficient, A1 is the oscillation amplitude, and θ is the damping coefficient.inv δ is the phase angle of the converter output voltage. SG P represents the power angle of the synchronous generator power supply. e f represents the electromagnetic power output of the synchronous generator. P Indicates the frequency of the active oscillation mode. Indicates the initial phase.

[0037] Optionally, the determining module includes:

[0038] The first determining module is used to determine the equivalent reactance curve and equivalent resistance curve of the power system based on the voltage increment and current increment through an impedance identification algorithm.

[0039] The second determining module is used to determine the active oscillation mode frequency, converter port voltage phase angle oscillation parameters, and synchronous generator parameters based on the equivalent reactance curve and the equivalent resistance curve.

[0040] The third determining module is used to determine the maximum rate of change of frequency under power disturbance based on the active oscillation mode frequency, converter port voltage phase angle oscillation parameters, synchronous generator parameters, and objective function.

[0041] Optionally, the power system stability determination device can also be used for:

[0042] If the first condition is met, the power system is determined to be in a weakly damped state; wherein the first condition includes:

[0043] At least one of the equivalent reactance curve and the equivalent resistance curve has a zero-crossing point, and the frequency value of the zero-crossing point is within a first range, while the absolute value of the curve slope at the zero-crossing point is within a second range.

[0044] The frequency of the active oscillation mode is:

[0045] f P =50-f r

[0046] Among them, f P f represents the frequency of the active oscillation mode. r The frequency of at least one zero-crossing point in the equivalent reactance curve and the equivalent resistance curve.

[0047] Thirdly, embodiments of this application also provide an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the power system stability determination method described above.

[0048] Fourthly, embodiments of this application also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the power system stability determination method described above.

[0049] The power system stability determination method of this application embodiment includes constructing a power system stability determination model. The power system stability determination model includes collecting the voltage increment and current increment of the power system when the power system receives a disturbance signal. The power system includes a converter and a synchronous generator.

[0050] The maximum rate of change of frequency under power disturbance is determined based on the voltage increment, current increment, and objective function. The maximum rate of change of frequency under power disturbance is used to determine the stability of the power system.

[0051] The objective function is defined as maximizing the rate of frequency change of the power system under power disturbances. This objective function is constructed based on the active power oscillation mode frequency, converter port voltage phase angle oscillation parameters, and synchronous generator parameters. The active power oscillation mode frequency is the power fluctuation frequency caused by the low-frequency oscillation phenomenon resulting from the grid connection of the converter in the power system. This method, by collecting voltage and current increments of the power system and combining them with the objective function constructed based on multiple parameters, determines the maximum rate of frequency change under power disturbances. It also considers potential weakly damped states in the system. Compared to existing methods that only analyze the frequency change characteristics of a given active power disturbance, this method comprehensively considers the influence of converter low-frequency oscillations and frequency coupling characteristics on the rate of frequency change, enabling a more comprehensive assessment of power system stability and resulting in more accurate stability determinations. Attached Figure Description

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

[0053] Figure 1 This is a flowchart of the power system stability determination method provided in the embodiments of this application;

[0054] Figure 2 This is a structural diagram of a power system stability determination device provided in an embodiment of this application;

[0055] Figure 3 This is a structural diagram of an electronic device provided in an embodiment of this application;

[0056] Figure 4 This is a flowchart illustrating the calculation of the maximum frequency change rate under power disturbance provided in one embodiment of this application;

[0057] Figure 5 This is a structural diagram of a grid-connected control converter system according to an embodiment of this application;

[0058] Figure 6 This is a structural diagram of impedance identification for a "black / grey box" power device provided in one embodiment of this application;

[0059] Figure 7 This is an impedance frequency response curve provided in one embodiment of this application. Detailed Implementation

[0060] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0061] This application provides a method for determining the stability of a power system. See also... Figure 1 , Figure 1 This is a flowchart of the power system stability determination method provided in the embodiments of this application, such as... Figure 1 As shown, it includes the following steps:

[0062] Step 101: When the power system receives a disturbance signal, the voltage increment and current increment of the power system are collected. The power system includes converters and synchronous generators.

[0063] In this step, the aforementioned power system, during actual operation, is subject to various natural and human-induced disturbances, such as lightning strikes, short-circuit faults, sudden load changes, and sudden generator tripping. These real-world scenarios can be simulated by applying disturbance signals, allowing for observation and analysis of the power system's dynamic response under disturbance in a laboratory or simulation environment. The stability of the aforementioned power system refers to its ability to recover to its original operating state or transition to a new stable operating state after being disturbed. When the power system is affected by disturbance signals, the changes in parameters such as frequency, voltage, and power can be observed by real-time acquisition of voltage and current increments, thereby assessing the system's stability and providing a data foundation for subsequent analysis. This application does not specifically limit how the power system receives disturbance signals or the specific form of the disturbance signals. The disturbance signals can be caused by natural factors, such as lightning strikes, severe weather, or earthquakes; or they can be caused by human factors, such as those imposed by users or caused by sudden load changes. The type of disturbance signal can be a sudden rise or fall in voltage or current, or a fluctuation in voltage or current. This application does not specifically limit the type of disturbance signal.

[0064] Since converters and synchronous generators are important components in a power system, changes in their operating status will be reflected in changes in voltage and current. Therefore, it is necessary to collect relevant data on a power system that includes converters and synchronous generators in order to obtain dynamic information of the system under disturbances.

[0065] Step 102: Determine the maximum rate of change of frequency under power disturbance based on the voltage increment, current increment, and objective function. The maximum rate of change of frequency under power disturbance is used to determine the stability of the power system.

[0066] The objective function includes an objective function that aims to maximize the rate of change of frequency of the power system under power disturbance. The objective function is constructed based on the active oscillation mode frequency, the phase angle oscillation parameters of the converter port voltage, and the synchronous generator parameters. The active oscillation mode frequency is the power fluctuation frequency under the low-frequency oscillation phenomenon caused by the grid connection of the converter in the power system.

[0067] In this step, the voltage and current increments mentioned above can be understood as the changes in voltage and current values ​​of the power system before and after a disturbance. For example, assuming the voltage at a node is 10kV during normal operation and becomes 9.8kV after a disturbance, the voltage increment is 0.2kV. The maximum rate of change of frequency under power disturbance is determined by collecting the voltage and current increments and combining them with a specific objective function. When the active power of the system is unbalanced, it will cause a change in the system frequency. If the generating power is less than the load power, the system frequency will decrease; conversely, the system frequency will increase. The frequency change rate mentioned above can be understood as the rate of change of the system frequency over time. When the system is subjected to a large disturbance, the frequency change rate may be very large. For example, in the event of a sudden generator trip, the system frequency may drop rapidly, and the frequency change rate may reach a few tenths of a hertz per second or even higher.

[0068] The aforementioned maximum rate of frequency change can be understood as follows: if the maximum rate of frequency change under power disturbance is less than this threshold, it indicates that the frequency change of the system is within a controllable range after being subjected to power disturbance. The system can maintain stable operation through its own adjustment mechanisms, such as generator speed governor adjustment or automatic load adjustment, and can be judged to have good stability. Conversely, if the maximum rate of frequency change exceeds the threshold, it means that the system frequency change is too drastic, which may cause some equipment in the system, such as generators or loads, to malfunction, or even trigger a chain reaction leading to system collapse, and the system stability is judged to be poor.

[0069] Furthermore, the maximum rate of change of frequency under power disturbances can also reflect the system's ability to overcome inertia and adjust its frequency instantly when subjected to a disturbance. If the system has greater inertia and stronger adjustment capability, its rate of change of frequency will be relatively smaller when subjected to power disturbances; conversely, its rate of change of frequency will be larger. Therefore, in some alternative implementations, the system's inertia and adjustment capability can be determined by the maximum rate of change of frequency, thereby judging the system's stability. For example, a power system mainly composed of large synchronous generators has greater rotor inertia, and its maximum rate of change of frequency is relatively smaller when subjected to the same power disturbance, indicating that the system has good stability; while a system containing a large number of distributed power sources and power electronic devices has relatively smaller inertia, and its maximum rate of change of frequency may be larger, indicating relatively poor stability.

[0070] In some optional implementations, the trend of the maximum rate of change of frequency under power disturbance over time can also be observed. If the maximum rate of change of frequency gradually decreases after the disturbance occurs, it indicates that the system's regulation mechanism is functioning effectively, suppressing frequency changes, and the system shows a tendency to recover stability, indicating good system stability. Conversely, if the maximum rate of change of frequency continues to increase or remains at a high level, it indicates that the system's regulation capability is insufficient and unable to control frequency changes, and the system may gradually lose stability. For example, in a power system containing multiple generators and loads, after a power disturbance, the initial maximum rate of change of frequency is 0.4 Hz / s, but as time progresses, this value gradually decreases to 0.1 Hz / s, indicating that the system is recovering stability; if the maximum rate of change of frequency continues to increase from 0.4 Hz / s to 0.6 Hz / s, it indicates that the system stability is deteriorating.

[0071] The objective function is designed to maximize the rate of change of power system frequency under power disturbances. Its foundation includes the active power oscillation mode frequency, which is the power fluctuation frequency triggered by low-frequency oscillations caused by converter grid connection. This frequency reflects the low-frequency oscillation characteristics of the system, which leads to frequency fluctuations. Severe oscillations may cause the rate of change of frequency to exceed the allowable range, affecting the frequency stability of the power system.

[0072] The aforementioned converter port voltage phase angle oscillation parameters reflect the oscillation characteristics of the converter output voltage phase angle; the aforementioned synchronous generator parameters describe the operating state and characteristics of the synchronous generator. By constructing an objective function by integrating these parameters, the influence of various factors in the system on the frequency change rate can be considered more comprehensively. The determined maximum frequency change rate under power disturbances can then be used to accurately determine the stability of the power system. In some other optional implementations, the maximum frequency change rate under power disturbances can be combined with other power system stability indicators, such as voltage stability indicators or power angle stability indicators, for comprehensive judgment. When the maximum frequency change rate is within the normal range, but the voltage fluctuates significantly or the generator power angle shows signs of instability, the system cannot still be determined to be stable. Only when all indicators meet the stability requirements can the power system be determined to have high stability.

[0073] To determine the maximum rate of frequency change under power disturbance based on the voltage increment, current increment, and objective function, a specific function model can be constructed. The aforementioned parameters are input, and the objective function is solved to obtain the maximum rate of frequency change under power disturbance. In some other optional implementations, the objective function can be pre-calculated through extensive simulation experiments or actual tests for different combinations of voltage and current increments, yielding the corresponding maximum rate of frequency change under power disturbance, and these data are then compiled into a table. In practical applications, after obtaining real-time voltage and current increments, the maximum rate of frequency change corresponding to the closest combination is found in the table as an approximate result.

[0074] In addition, in some alternative implementations, a neural network model can be constructed as the specific form of the objective function, with voltage and current increments as nodes in the input layer and the maximum rate of change of frequency under power disturbances as nodes in the output layer. The neural network is trained using a large amount of historical data, allowing it to learn the complex nonlinear relationship between voltage and current increments and the maximum rate of change of frequency. In practical applications, by inputting real-time voltage and current increments into the trained neural network, the corresponding maximum rate of change of frequency can be obtained, thereby determining the stability of the power system.

[0075] The carrier device for the aforementioned objective function can be a server cluster, a cloud computing platform, a dedicated AI training workstation, etc. The deployment device for the objective function can be an industrial gateway, an edge server, a smart substation terminal, a mobile phone, a tablet computer, a laptop computer, a personal digital assistant (PDA), a mobile internet device (MID), or a smartwatch, etc.

[0076] The maximum rate of change of frequency under the aforementioned power disturbance is used to determine the stability of the power system. The specific determination method is not specifically limited in the embodiments of this application. In some optional embodiments, the stability of the system can be determined by directly comparing the measured maximum rate of change of frequency of the power system with the threshold by setting a safety threshold for the maximum rate of change of frequency. For example, the safety threshold can be set based on power system design specifications or simulation analysis. If the measured maximum rate of change of frequency of the power system is less than the upper limit of the threshold and greater than the lower limit of the threshold, the system is determined to be stable; otherwise, an early warning is triggered.

[0077] In some other alternative implementations, the time series of the maximum rate of change of the power system frequency can be continuously recorded (e.g., sampling points within 10 seconds). The trend of the maximum rate of change of the power system frequency can be predicted using exponential smoothing or neural networks. If the absolute value of the maximum rate of change of the power system frequency gradually decreases and the trend prediction converges, the system is determined to be stable; if the trend diverges (e.g., σ<0) or continues to increase, the power system is determined to be unstable.

[0078] In the power system stability determination method of this application embodiment, the voltage and current increments of the power system are collected, and the maximum rate of frequency change under power disturbance is determined by combining the objective function constructed based on multiple parameters. Considering the possible weak damping state of the system, compared with the existing method that only analyzes the frequency change characteristics of the system caused by a given active disturbance, this method comprehensively considers the influence of converter low-frequency oscillation and frequency coupling characteristics on the rate of frequency change, and can more comprehensively determine the stability of the power system, making the determination result of power system stability more accurate.

[0079] Optionally, the converter port voltage phase angle oscillation parameters include oscillation amplitude and initial phase; and / or,

[0080] The synchronous generator parameters include the synchronous generator output electromagnetic power, the synchronous generator power angle, the rotor inertia time constant, and the damping coefficient.

[0081] In the power system stability determination method of this application embodiment, the above-mentioned oscillation amplitude can be understood as the maximum deviation of the converter port voltage phase angle from its steady-state value during oscillation. It describes the severity of the voltage phase angle oscillation; the larger the amplitude, the more severe the phase angle oscillation. The above-mentioned initial phase can be understood as the phase of the converter port voltage phase angle oscillation starting moment relative to the reference moment. It determines the starting position of the oscillation; different initial phases will result in different starting points of the oscillation on the time axis. The above-mentioned synchronous generator output electromagnetic power can be understood as the electrical power output to the power system after the synchronous generator converts mechanical energy into electrical energy through the principle of electromagnetic induction, which can reflect the generator's power generation capacity. The above-mentioned synchronous generator power angle can be understood as the angle between the rotor magnetic field axis and the stator magnetic field axis of the synchronous generator. The above-mentioned rotor inertia time constant represents the time required for the generator rotor to accelerate from rest to rated speed under rated power. The larger the inertia time constant, the greater the rotor inertia, and the slower the rotor speed changes when subjected to external disturbances. The damping coefficient is a parameter describing the damping effect of the synchronous generator on oscillations during operation. It represents the generator's ability to suppress rotor oscillations after being disturbed. The larger the damping coefficient, the stronger the generator's ability to suppress oscillations.

[0082] In some alternative implementations, the aforementioned oscillation amplitude and initial phase can be obtained by acquiring and processing voltage signals using voltage sensors and phase measurement devices installed at the converter ports to calculate the oscillation amplitude and initial phase. The parameters for the synchronous generator's output electromagnetic power, synchronous generator power angle, rotor inertia time constant, and damping coefficient can be obtained by retrieving the synchronous generator's equipment parameters.

[0083] In the power system stability determination method of this application embodiment, by comprehensively considering the converter port voltage phase angle oscillation parameters and synchronous generator parameters, the stability and dynamic performance of the power system can be determined more accurately. Furthermore, based on the more accurate power system stability determination results, system oscillations can be suppressed more effectively, the occurrence of system faults can be reduced, and the safe, reliable, and efficient operation of the power system can be ensured.

[0084] Optionally, the objective function includes:

[0085]

[0086] P e =k1Δδ SG -k2Δθ inv

[0087] ω f =2πf P

[0088] Where M is the rotor inertia time constant, D is the damping coefficient, and Δθ inv σ is the disturbance of the phase angle of the converter output voltage. SSO Where A is the damping coefficient, A1 is the oscillation amplitude, and θ is the damping coefficient. inv δ is the phase angle of the converter output voltage. SG P represents the power angle of the synchronous generator power supply. e f represents the electromagnetic power output of the synchronous generator. P Indicates the frequency of the active oscillation mode. Indicates the initial phase.

[0089] In the power system stability determination method of this application embodiment, the objective function is specifically constructed as shown in the above formula. The objective function aims to maximize the rate of frequency change under power disturbance. By obtaining the known oscillation amplitude and initial phase, the electromagnetic power output of the synchronous generator, the power angle of the synchronous generator power supply, the rotor inertia time constant and damping coefficient, the characteristics of the synchronous generator and the converter are comprehensively considered. Through the analysis of parameters such as frequency and power, the stability of the power system under disturbance can be accurately evaluated, thus providing a guarantee for the safe operation of the system.

[0090] In some alternative implementations, in the weakly damped mode, σSSO If the value is less than or close to 0, the variable on the right-hand side of the objective function above can be simplified to:

[0091]

[0092] The particular solution of the objective function can be expressed in the following form:

[0093]

[0094] Where, σ SSO A1 is the damping coefficient, and A2 is the oscillation amplitude. Indicates the initial phase, A2, Represents the coefficients of the second-order differential equation and the oscillation amplitude A1ω f and A2 is a constant that determines the frequency change rate of the power system under the power disturbance.

[0095] In some optional implementations, control strategies can be tailored based on the calculation results of the objective function, such as adjusting generator operating parameters and optimizing converter control algorithms, to improve the system's anti-interference capability and stability. Furthermore, in other optional implementations, the aforementioned objective function can also be used in the planning and design phases of power systems. Using this objective function, simulation analyses can be performed on different system configurations and parameters, thereby further optimizing the power system design based on the stability determination results derived from the objective function, ultimately improving system performance and reliability.

[0096] In the power system stability determination method of this application embodiment, by establishing an objective function that couples the inertial response and damping characteristics of the power system with the low-frequency oscillation of the converter, the system comprehensively reflects the multi-physics coupling characteristics of the system while accurately quantifying the impact of low-frequency oscillation on frequency stability. This allows for more accurate acquisition of the maximum frequency change rate of the power system under power disturbance, thereby enabling more accurate quantitative analysis and determination of the frequency stability of the power system under power disturbance.

[0097] Optionally, determining the maximum rate of change of frequency under power disturbance based on the voltage increment, current increment, and objective function includes:

[0098] The equivalent reactance curve and equivalent resistance curve of the power system are determined by an impedance identification algorithm based on the voltage and current increments.

[0099] The active power oscillation mode frequency, converter port voltage phase angle oscillation parameters, and synchronous generator parameters are determined based on the equivalent reactance curve and the equivalent resistance curve.

[0100] The maximum rate of change of frequency under power disturbance is determined based on the active oscillation mode frequency, converter port voltage phase angle oscillation parameters, synchronous generator parameters, and objective function.

[0101] In the power system stability determination method of this application embodiment, an external characteristic measurement method based on small disturbance injection can be used to obtain the equipment impedance model, thereby obtaining the equivalent reactance curve and equivalent resistance curve of the power system. For example, a disturbance voltage (or current) of a specific frequency can be injected at the equipment port, and the voltage and current increments at the port can be measured and recorded simultaneously. This treats the power system as a black box or gray box, and the impedance frequency characteristic curve is obtained through external characteristic measurement. (Refer to...) Figure 4 .

[0102] The aforementioned active oscillation mode frequency can be understood as the power fluctuation frequency under the low-frequency oscillation phenomenon caused by converter grid connection in the power system. The determination of the maximum frequency change rate under power disturbance based on the aforementioned active oscillation mode frequency, converter port voltage phase angle oscillation parameters, synchronous generator parameters and objective function can be understood as inputting the obtained parameters into the constructed objective function. The particular solution of the objective function is the maximum frequency change rate under power disturbance.

[0103] In this implementation, by injecting a wideband disturbance signal and measuring the voltage or current increment, the impedance identification algorithm can obtain the equivalent reactance and equivalent resistance curves of the power system at different frequencies. These curves intuitively reflect the system's response capability to disturbances at specific frequencies. By analyzing the curve characteristics, the frequency and damping characteristics of the dominant oscillation mode can be quickly identified, providing a quantitative basis for subsequently determining the active power oscillation mode frequency, converter port voltage phase angle oscillation parameters, and synchronous generator parameters. For example, the converter port voltage phase angle oscillation parameters can be accurately obtained by using a Simulink linearized model combined with curve characteristics. Furthermore, the impedance identification algorithm supports online monitoring and can update the equivalent reactance / resistance curves and related parameters in real time, adapting to changes in the power system's operating conditions.

[0104] In the power system stability determination method of this application embodiment, the equivalent reactance curve and equivalent resistance curve of the power system are determined by an impedance identification algorithm; the active power oscillation mode frequency, converter port voltage phase angle oscillation parameters, and synchronous generator parameters are determined based on the equivalent reactance curve and the equivalent resistance curve, directly linking the low-frequency oscillation of the converter with the dynamic characteristics of the synchronous generator, and intuitively identifying potential oscillation risks through the impedance curve, thereby achieving the observability of the oscillation mode, quantifying the contribution of converter oscillation to the rate of frequency change, and making the determination of power system stability more accurate.

[0105] Optionally, after determining the equivalent reactance curve and equivalent resistance curve of the power system using the impedance identification algorithm based on the voltage increment and current increment, the method further includes:

[0106] If the first condition is met, the power system is determined to be in a weakly damped state; wherein the first condition includes:

[0107] At least one of the equivalent reactance curve and the equivalent resistance curve has a zero-crossing point, and the frequency value of the zero-crossing point is within a first range, while the absolute value of the curve slope at the zero-crossing point is within a second range.

[0108] The frequency of the active oscillation mode is:

[0109] f P =50-f r

[0110] Among them, f P f represents the frequency of the active oscillation mode. r The frequency of at least one zero-crossing point in the equivalent reactance curve and the equivalent resistance curve.

[0111] In the power system stability determination method of this application embodiment, the zero-crossing point of the equivalent reactance or resistance curve indicates that the reactance or resistance of the system is zero at that frequency, which can correspond to the inherent oscillation mode of the system. The first range can be understood as focusing on low-frequency oscillations near the power frequency. This range is closely related to the subsynchronous oscillations or inter-synchronous oscillations caused by converter grid connection, avoiding misjudgment of other high-frequency interferences. The specific selection of the first range is not specifically limited in this application embodiment. For example, the first range can be a range close to 50Hz, such as [49, 51], which can be the first range. The second range is also not limited in this application embodiment, and can be any range that is not close to infinity.

[0112] In some alternative implementations, when impedance analysis determines that a low-frequency oscillation mode exists in the system, the phase angle of the converter output voltage exhibits the following oscillation pattern:

[0113]

[0114] Where Δθ inv For θ inv The disturbance amount, A1 is the oscillation amplitude, σ SSO For damping, ω f =2πf P , This is the initial phase. Variable A1, This can be obtained using Simulink linearization tools;

[0115]

[0116] Furthermore, the equation for the output electromagnetic power of the synchronous machine is as follows:

[0117] P e =E SG EB SG sin(δ SG -δ)+E SG E inv B inv sin(δ SG -θ inv )

[0118] Among them, E SG E, E inv These represent the voltage amplitudes at the synchronous machine nodes, the infinite bus, and the converter ports, respectively. B SG and B inv These are the admittances between the synchronous machine and the infinite bus, and between the converter and the synchronous machine, respectively. θ inv δ is the phase angle of the converter output voltage. SG δ and δ represent the power angles of the synchronous machine and the infinite power supply, respectively.

[0119] The equation of motion for the synchronous machine rotor is:

[0120]

[0121] Where M is the rotor inertia time constant, and D is the damping coefficient. Substituting these values ​​into the above synchronous machine output electromagnetic power equation, the synchronous machine rotor motion equation can be transformed into:

[0122]

[0123] in:

[0124] k1 = EE SG B SG cosδ SG0 +E SG E inv B inv cos(δ SG0 -θ inv0 )

[0125] k2=E SG E inv B inv cos(δ SG0 -θ inv0 )

[0126] Therefore, the objective function is:

[0127]

[0128] P e =k1Δδ SG -k2Δθ inv

[0129] ω f =2πf P

[0130] Where M is the rotor inertia time constant, D is the damping coefficient, and Δθ inv σ is the disturbance of the phase angle of the converter output voltage. SSO Where A is the damping coefficient, A1 is the oscillation amplitude, and θ is the damping coefficient. inv δ is the phase angle of the converter output voltage. SG P represents the power angle of the synchronous generator power supply. e f represents the electromagnetic power output of the synchronous generator. P Indicates the frequency of the active oscillation mode. Indicates the initial phase.

[0131] In this implementation, the method of determining the weakly damped state of the power system based on equivalent reactance and equivalent resistance curves and calculating the active power oscillation mode frequency can accurately capture weak damping characteristics. Because the operating conditions of power systems are complex and variable in actual operation, low-frequency oscillations may gradually intensify imperceptibly. By monitoring the equivalent reactance and equivalent resistance curves in real time, once the first condition is met, it can be promptly determined that the system is in a weakly damped state, and potential oscillation risks can be detected in advance. Furthermore, accurately calculating the active power oscillation mode frequency allows the model to more accurately simulate the system's oscillation behavior, providing a deeper understanding of the system's oscillation situation and offering crucial basis for subsequent power system stability analysis.

[0132] In the power system stability determination method of this application embodiment, specifically, a three-phase disturbance voltage u with appropriate amplitude (capable of inducing measurable oscillations but not enough to change the operating point or induce unfavorable nonlinearity) is injected between the AC power grid and the target power equipment. ha u hb and u hc See also Figure 6 The impedance-frequency characteristic curve of the converter in the frequency band of interest is obtained.

[0133] When specific converter control parameters are used, the impedance-frequency characteristic curve of the resulting device (e.g., Figure 5 As shown in the figure, the near-power frequency oscillation mode frequency is 48.5 / 51.5Hz. At this frequency, the equivalent resistance is >0, indicating a weakly damped oscillation mode, with the oscillation component gradually decaying. σ SSO The phase oscillation frequency is calculated using the formula and is found to be 50-48.5=1.5Hz.

[0134] In Simulink Figure 5 The target system is modeled linearly, and the active power reference value P of the converter is set. ref A small perturbation (e.g., a step of 0.1 pu) is generated, and the following parameters are obtained: oscillation amplitude A1, initial phase angle. Obtain the synchronous machine parameters: rotor inertia time constant M and damping coefficient D. Based on the existing synchronous machine and AC system parameters, calculate k1 and k2, and then solve the objective function to obtain the maximum rate of frequency change under power disturbance. Based on the obtained maximum rate of frequency change under power disturbance, further determine the stability of the current power system.

[0135] See Figure 2 , Figure 2 This is a structural diagram of a power system stability determination device provided in another embodiment of this application.

[0136] like Figure 2 As shown, the power system stability determination device 200 includes:

[0137] The acquisition module 201 is used to acquire the voltage increment and current increment of the power system when the power system receives a disturbance signal. The power system includes a converter and a synchronous generator.

[0138] The determination module 202 is used to determine the maximum rate of change of frequency under power disturbance based on the voltage increment, current increment and objective function, wherein the maximum rate of change of frequency under power disturbance is used to determine the stability of the power system;

[0139] The objective function is a function that aims to maximize the rate of change of frequency of the power system under power disturbance. The objective function is constructed based on the active oscillation mode frequency, the phase angle oscillation parameters of the converter port voltage, and the synchronous generator parameters. The active oscillation mode frequency is the power fluctuation frequency under the low-frequency oscillation phenomenon caused by the grid connection of the converter in the power system.

[0140] Optionally, the converter port voltage phase angle oscillation parameters include oscillation amplitude and initial phase; and / or,

[0141] The synchronous generator parameters include the synchronous generator output electromagnetic power, the synchronous generator power angle, the rotor inertia time constant, and the damping coefficient.

[0142] Optionally, the objective function includes:

[0143]

[0144] P e =k1Δδ SG -k2Δθ inv

[0145] ω f =2πf P

[0146] Where M is the rotor inertia time constant, D is the damping coefficient, and Δθ inv σ is the disturbance of the phase angle of the converter output voltage. SSO Where A is the damping coefficient, A1 is the oscillation amplitude, and θ is the damping coefficient. inv δ is the phase angle of the converter output voltage. SG P represents the power angle of the synchronous generator power supply. e f represents the electromagnetic power output of the synchronous generator. P Indicates the frequency of the active oscillation mode. Indicates the initial phase.

[0147] Optionally, the determining module includes:

[0148] The first determining module is used to determine the equivalent reactance curve and equivalent resistance curve of the power system based on the voltage increment and current increment through an impedance identification algorithm.

[0149] The second determining module is used to determine the active oscillation mode frequency, converter port voltage phase angle oscillation parameters, and synchronous generator parameters based on the equivalent reactance curve and the equivalent resistance curve.

[0150] The third determining module is used to determine the maximum rate of change of frequency under power disturbance based on the active oscillation mode frequency, converter port voltage phase angle oscillation parameters, synchronous generator parameters, and objective function.

[0151] Optionally, the power system stability determination device can also be used for:

[0152] If the first condition is met, the power system is determined to be in a weakly damped state; wherein the first condition includes:

[0153] At least one of the equivalent reactance curve and the equivalent resistance curve has a zero-crossing point, and the frequency value of the zero-crossing point is within a first range, while the absolute value of the curve slope at the zero-crossing point is within a second range.

[0154] The frequency of the active oscillation mode is:

[0155] f P =50-f r

[0156] Among them, f P f represents the frequency of the active oscillation mode. r The frequency of at least one zero-crossing point in the equivalent reactance curve and the equivalent resistance curve.

[0157] See Figure 3 , Figure 3 This is a structural diagram of an electronic device provided in another embodiment of this application, such as... Figure 3 As shown, the electronic device includes: a processor 301, a communication interface 302, a communication bus 304, and a memory 303, wherein the processor 301, the communication interface 302, and the memory 303 interact with each other through the communication bus 304.

[0158] The memory 303 is used to store computer programs; the processor 301 is used to collect the voltage increment and current increment of the power system when the power system receives a disturbance signal, the power system including a converter and a synchronous generator.

[0159] The maximum rate of change of frequency under power disturbance is determined based on the voltage increment, current increment, and objective function. The maximum rate of change of frequency under power disturbance is used to determine the stability of the power system.

[0160] The objective function is a function that aims to maximize the rate of change of frequency of the power system under power disturbance. The objective function is constructed based on the active oscillation mode frequency, the phase angle oscillation parameters of the converter port voltage, and the synchronous generator parameters. The active oscillation mode frequency is the power fluctuation frequency under the low-frequency oscillation phenomenon caused by the grid connection of the converter in the power system.

[0161] Optionally, the converter port voltage phase angle oscillation parameters include oscillation amplitude and initial phase; and / or,

[0162] The synchronous generator parameters include the synchronous generator output electromagnetic power, the synchronous generator power angle, the rotor inertia time constant, and the damping coefficient.

[0163] Optionally, the objective function is:

[0164]

[0165] P e =k1Δδ SG -k2Δθ inv

[0166] ω f =2πf P

[0167] Where M is the rotor inertia time constant, D is the damping coefficient, and Δθ inv σ is the disturbance of the phase angle of the converter output voltage. SSO Where A is the damping coefficient, A1 is the oscillation amplitude, and θ is the damping coefficient. inv δ is the phase angle of the converter output voltage. SG P represents the power angle of the synchronous generator power supply. ef represents the electromagnetic power output of the synchronous generator. P Indicates the frequency of the active oscillation mode. Indicates the initial phase.

[0168] Optionally, determining the maximum rate of change of frequency under power disturbance based on the voltage increment, current increment, and objective function includes:

[0169] The equivalent reactance curve and equivalent resistance curve of the power system are determined by an impedance identification algorithm based on the voltage and current increments.

[0170] The active power oscillation mode frequency, converter port voltage phase angle oscillation parameters, and synchronous generator parameters are determined based on the equivalent reactance curve and the equivalent resistance curve.

[0171] The maximum rate of change of frequency under power disturbance is determined based on the active oscillation mode frequency, converter port voltage phase angle oscillation parameters, synchronous generator parameters, and objective function.

[0172] Optionally, after determining the equivalent reactance curve and equivalent resistance curve of the power system using the impedance identification algorithm based on the voltage increment and current increment, the method further includes:

[0173] If the first condition is met, the power system is determined to be in a weakly damped state; wherein the first condition includes:

[0174] At least one of the equivalent reactance curve and the equivalent resistance curve has a zero-crossing point, and the frequency value of the zero-crossing point is within a first range, while the absolute value of the curve slope at the zero-crossing point is within a second range.

[0175] The frequency of the active oscillation mode is:

[0176] f P =50-f r

[0177] Among them, f P f represents the frequency of the active oscillation mode. r The frequency of at least one zero-crossing point in the equivalent reactance curve and the equivalent resistance curve.

[0178] The communication bus 304 mentioned in the above electronic device can be a Peripheral Component Interconnect (PCT) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus 304 can be divided into an address bus, a data bus, a control bus, etc. For ease of identification, it is represented by only one thick line in the figure, but this does not indicate that there is only one bus or one type of data.

[0179] Communication interface 302 is used for communication between the aforementioned terminal and other devices.

[0180] The memory 303 may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory 303 may also be at least one storage device located remotely from the aforementioned processor 301. The aforementioned processor 301 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0181] This application also provides a computer-readable storage medium storing a computer program. When executed by a processor, this computer program implements the various processes of the above-described power system stability determination method embodiments and achieves the same technical effects. To avoid repetition, it will not be described again here. The computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0182] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0183] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0184] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for determining the stability of a power system, characterized in that, The method includes: When the power system receives a disturbance signal, the voltage increment and current increment of the power system, which includes converters and synchronous generators, are collected. The maximum rate of change of frequency under power disturbance is determined based on the voltage increment, current increment, and objective function. The maximum rate of change of frequency under power disturbance is used to determine the stability of the power system. The objective function is a function that aims to maximize the rate of change of frequency of the power system under power disturbance. The objective function is constructed based on the active oscillation mode frequency, the phase angle oscillation parameters of the converter port voltage, and the synchronous generator parameters. The active oscillation mode frequency is the power fluctuation frequency under the low-frequency oscillation phenomenon caused by the grid connection of the converter in the power system.

2. The method according to claim 1, characterized in that, The converter port voltage phase angle oscillation parameters include the oscillation amplitude and the initial phase; and / or, The synchronous generator parameters include the synchronous generator output electromagnetic power, the synchronous generator power angle, the rotor inertia time constant, and the damping coefficient.

3. The method according to claim 2, characterized in that, The objective function is: P e =k1Δδ SG -k2Δθ inv oh f =2πf P Where M is the rotor inertia time constant, D is the damping coefficient, and Δθ inv σ is the disturbance of the phase angle of the converter output voltage. SSO Where A is the damping coefficient, A1 is the oscillation amplitude, and θ is the damping coefficient. inv δ is the phase angle of the converter output voltage. SG P represents the power angle of the synchronous generator power supply. e f represents the electromagnetic power output of the synchronous generator. P Indicates the frequency of the active oscillation mode. Indicates the initial phase.

4. The method according to any one of claims 1 to 3, characterized in that, The step of determining the maximum rate of change of frequency under power disturbance based on the voltage increment, current increment, and objective function includes: The equivalent reactance curve and equivalent resistance curve of the power system are determined by an impedance identification algorithm based on the voltage and current increments. The active power oscillation mode frequency, converter port voltage phase angle oscillation parameters, and synchronous generator parameters are determined based on the equivalent reactance curve and the equivalent resistance curve. The maximum rate of change of frequency under power disturbance is determined based on the active oscillation mode frequency, converter port voltage phase angle oscillation parameters, synchronous generator parameters, and objective function.

5. The method according to claim 4, characterized in that, After determining the equivalent reactance curve and equivalent resistance curve of the power system using the impedance identification algorithm based on the voltage increment and current increment, the method further includes: If the first condition is met, the power system is determined to be in a weakly damped state; wherein the first condition includes: At least one of the equivalent reactance curve and the equivalent resistance curve has a zero-crossing point, and the frequency value of the zero-crossing point is within a first range, while the absolute value of the curve slope at the zero-crossing point is within a second range. The frequency of the active oscillation mode is: f P =50-f r Among them, f P f represents the frequency of the active oscillation mode. r The frequency of at least one zero-crossing point in the equivalent reactance curve and the equivalent resistance curve.

6. A power system stability determination device, characterized in that, The device includes: The acquisition module is used to acquire the voltage increment and current increment of the power system, which includes converters and synchronous generators, when the power system receives a disturbance signal. The determination module is used to determine the maximum rate of change of frequency under power disturbance based on the voltage increment, current increment and objective function, wherein the maximum rate of change of frequency under power disturbance is used to determine the stability of the power system; The objective function is a function that aims to maximize the rate of change of frequency of the power system under power disturbance. The objective function is constructed based on the active oscillation mode frequency, the phase angle oscillation parameters of the converter port voltage, and the synchronous generator parameters. The active oscillation mode frequency is the power fluctuation frequency under the low-frequency oscillation phenomenon caused by the grid connection of the converter in the power system.

7. The apparatus according to claim 6, characterized in that, The converter port voltage phase angle oscillation parameters include the oscillation amplitude and the initial phase; and / or, The synchronous generator parameters include the synchronous generator output electromagnetic power, the synchronous generator power angle, the rotor inertia time constant, and the damping coefficient.

8. The apparatus according to claim 6, characterized in that, The objective function is: P e =k1Δδ SG -k2Δθ inv oh f =2πf P Where M is the rotor inertia time constant, D is the damping coefficient, and Δθ inv σ is the disturbance of the phase angle of the converter output voltage. SSO Where A is the damping coefficient, A1 is the oscillation amplitude, and θ is the damping coefficient. inv δ is the phase angle of the converter output voltage. SG P represents the power angle of the synchronous generator power supply. e f represents the electromagnetic power output of the synchronous generator. P Indicates the frequency of the active oscillation mode. Indicates the initial phase.

9. An electronic device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the computer program is executed by the processor, it implements the steps of the power system stability determination method as described in any one of claims 1 to 5.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the power system stability determination method as described in any one of claims 1 to 5.

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