Electric power system transient state active supporting capability characterization evaluation method and related device

Abstract

The invention relates to the technical field of electric power system evaluation, and discloses an electric power system transient active support capability representation evaluation method and a related device, the electric power system transient active support capability representation evaluation method comprises the following steps: collecting power data and frequency data of an electric power system; performing parameter identification on the power data and the frequency data based on an ARMAX power system model to obtain an inertia evaluation value; calculating the minimum safety inertia of the power system based on the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint of the power system; dividing the inertia interval into a high inertia interval, a low inertia interval and an insufficient inertia interval based on the minimum safety inertia; and determining the inertia state of the current power system based on the inertia evaluation value, and when the inertia evaluation value is in an inertia insufficient interval, performing inertia early warning. According to the method, the inertia distribution characteristics of the power system can be evaluated more meticulously, and the evaluation accuracy of the transient active supporting capability characterization is improved.

Description

Technical Field

[0001] The present invention relates to the field of power system technical evaluation, and in particular to a method for characterizing and evaluating the transient active support capability of a power system and a related device. Background Art

[0002] In the current power system architecture, with the dynamic changes in the penetration rate of new energy, control strategies and the working state of the system, the equivalent inertia of the power system is no longer a fixed value. Compared with the constant inertia of synchronous units, the equivalent inertia can better reveal the dynamic connection between system power imbalance and frequency change. In order to deeply analyze the joint impact of synchronous generators and new energy units on system inertia, it is necessary to rely on real-time measurement data of the power grid to accurately evaluate the equivalent inertia of the system.

[0003] In the current power system, in the field of inertia assessment of transient active power support capacity, current research focus is mostly on the inertia contribution of synchronous units, and it is impossible to analyze the inertia distribution characteristics of the power system, resulting in incomplete evaluation of the power system. Summary of the invention

[0004] In view of this, the present invention provides a method and related device for characterizing and evaluating the transient active support capability of an electric power system, so as to more carefully evaluate the inertia distribution characteristics of the electric power system and improve the accuracy of the characterization and evaluation of the transient active support capability.

[0005] In a first aspect, the present invention provides a method for characterizing and evaluating the transient active support capability of an electric power system, the method comprising: collecting power data and frequency data of the electric power system; performing parameter identification on the power data and frequency data based on an ARMAX electric power system model to obtain an inertia evaluation value; calculating the minimum safe inertia of the electric power system based on a frequency change rate safety threshold constraint and a frequency deviation safety threshold constraint of the electric power system; dividing the inertia interval into a high inertia interval, a low inertia interval and an insufficient inertia interval based on the minimum safe inertia; determining the inertia state of the current electric power system based on the inertia evaluation value, and performing an inertia warning when the inertia evaluation value is in the insufficient inertia interval.

[0006] In this implementation, the ARMAX parameter identification method is used to identify the system transfer function and obtain the inertia evaluation value. On this basis, the minimum safe inertia is determined based on the frequency change rate safety threshold constraint and frequency deviation safety threshold constraint of the power system, and the minimum safe inertia is used to characterize the safety boundary of the minimum frequency regulation capability of the power system and divide the inertia interval. Combined with the inertia evaluation value, the inertia distribution characteristics of the power system can be evaluated more intuitively and meticulously, and the accuracy of the transient active support capability characterization evaluation can be improved.

[0007] In an optional embodiment, parameter identification is performed on power data and frequency data based on an ARMAX power system identification model to obtain an inertia evaluation value, including: when the power system is in a stable frequency fluctuation state, dividing multiple data windows with a first preset time based on a sliding window technology; within the data window, calculating the first inertia value of the power data and frequency data based on the ARMAX power system identification model; and calculating the average value of the first inertia values ​​of multiple data windows to obtain an inertia evaluation value.

[0008] In an optional embodiment, parameter identification is performed on power data and frequency data based on an ARMAX power system identification model to obtain an inertia evaluation value, including: when the power system is in a power disturbance state, within a second preset time when the disturbance occurs, calculating a first inertia value of the power data and frequency data based on the ARMAX power system identification model; and using the first inertia value as the inertia evaluation value.

[0009] Inertia estimation methods based on measurement data mostly rely on large disturbance events, which makes it difficult to effectively monitor and warn the inertia of the power system in real time when the frequency fluctuates steadily. In this implementation method, inertia evaluation is performed in two scenarios, namely, steady-state frequency fluctuations and large disturbances. This can comprehensively consider steady-state frequency fluctuations and large disturbances to effectively monitor the power inertia.

[0010] In an optional embodiment, calculating the first inertia value of power data and frequency data based on the ARMAX power system identification model includes: obtaining a sampling interval; performing parameter identification on the power data and frequency data based on the ARMAX power system identification model according to the sampling interval to obtain a 2nd to 10th order discrete model of the power system; converting the discrete model of the power system into a continuous model of the power system; reducing the order of the continuous model of the power system to obtain a low-order model of the power system, and extracting the inertia time constant of each low-order model of the power system; calculating the average value of the inertia time constant to obtain the first inertia value.

[0011] In this implementation, the ARMAX parameter identification technology is combined to effectively identify the transfer function of the system, and obtain the key parts of the inertia response through model simplification, and then accurately calculate the inertia time constant, providing a basis for the subsequent calculation of the inertia evaluation value.

[0012] In an optional implementation, calculating the minimum safety inertia of the power system based on the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint of the power system includes: calculating the minimum first safety inertia based on the frequency change rate safety threshold constraint of the power system, wherein the frequency change rate safety threshold constraint of the power system is: in, is the first safety inertia, ΔP 0is the initial unbalanced power of the power system, Δf d is the frequency regulation dead zone of the power system, f 0 is the rated frequency of the power system, D is the damping coefficient of the power system, RoCoF max is the safety threshold of the frequency change rate of the power system; the minimum second safety inertia is calculated based on the frequency deviation safety threshold constraint of the power system, wherein the frequency deviation safety threshold constraint of the power system is: in, is the second safety inertia, Δf max is the safety threshold of the frequency deviation of the power system, R s is the power adjustment rate of the power system; take the maximum value of the minimum first safety inertia and the minimum second safety inertia to obtain the minimum safety inertia.

[0013] In this implementation, in order to quantify the frequency safety and stability risk of the power system after suffering an unbalanced power disturbance, the system inertia response is analyzed, and the minimum safe inertia under the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint is proposed as the inertia warning indicator, which can improve the accuracy of the inertia warning.

[0014] In an optional embodiment, the minimum safe inertia divides the inertia interval into a high inertia interval, a low inertia interval and an insufficient inertia interval, including: constructing an inertia safety margin index based on the minimum safe inertia; dividing the inertia area where the inertia safety margin is less than or equal to zero into an insufficient inertia interval; dividing the inertia area where the inertia safety margin is greater than zero and less than or equal to a first preset safety margin value into a low inertia interval; dividing the inertia area where the inertia safety margin is greater than the first preset safety margin value into a high inertia interval, wherein the first preset safety margin value is greater than zero.

[0015] In an optional implementation, determining the inertia state of the current power system using the inertia evaluation value includes: calculating the current inertia safety margin of the inertia evaluation value based on an inertia safety margin indicator; and calculating the current inertia safety margin to determine the inertia state of the current power system.

[0016] In this implementation, the inertia safety margin is introduced as an indicator for evaluating inertia. The safety warning helps power grid operators to understand the current inertia level of the system more intuitively and issue warnings in time when inertia is short, thereby effectively avoiding the risk of frequency instability.

[0017] In a second aspect, the present invention provides a device for characterizing and evaluating the transient active support capability of an electric power system, the device comprising: an acquisition module for acquiring power data and frequency data of the electric power system; an identification module for performing parameter identification on the power data and frequency data based on an ARMAX electric power system model to obtain an inertia evaluation value; a calculation module for calculating the minimum safe inertia of the electric power system based on a frequency change rate safety threshold constraint and a frequency deviation safety threshold constraint of the electric power system; a division module for dividing the inertia interval into a high inertia interval, a low inertia interval and an insufficient inertia interval based on the minimum safe inertia; and an evaluation module for determining the inertia state of the current electric power system based on the inertia evaluation value, and performing an inertia warning when the inertia evaluation value is in the insufficient inertia interval.

[0018] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the method for characterizing and evaluating the transient active support capability of a power system according to the first aspect or any corresponding embodiment thereof by executing the computer instructions.

[0019] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the method for characterizing and evaluating the transient active support capability of a power system according to the first aspect or any corresponding embodiment thereof.

[0020] In a fifth aspect, the present invention provides a computer program product, comprising computer instructions for causing a computer to execute the method for characterizing and evaluating the transient active support capability of a power system according to the first aspect or any corresponding embodiment thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a flow chart of a method for characterizing and evaluating the transient active support capability of a power system according to an embodiment of the present invention;

[0023] Figure 2 is a flow chart of another method for characterizing and evaluating the transient active support capability of a power system according to an embodiment of the present invention;

[0024] Figure 3is a schematic diagram of power during a frequency dynamic response process according to an embodiment of the present invention;

[0025] Figure 4 is a schematic diagram of inertia intervals according to an embodiment of the present invention;

[0026] Figure 5 is a structural block diagram of a device for characterizing and evaluating the transient active power support capability of a power system according to an embodiment of the present invention;

[0027] Figure 6 It is a structural schematic diagram of a computer device provided by an optional embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 described embodiments are 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0029] In modern power systems, transient support capability refers to the ability of power systems to quickly and effectively maintain system frequency and voltage stability and ensure continuous and reliable power supply after being subjected to sudden disturbances, such as load mutations and short circuit faults. This capability constitutes the core of power system resilience and is directly related to the safe and stable operation of the power grid and the quality of power supply.

[0030] Among them, transient support capability mainly includes three parts: one is frequency support capability, which measures the ability of the power system to maintain the system frequency within the specified range by adjusting the generator output or using energy storage devices when facing power imbalance; the second is voltage support capability, which focuses on the ability of the power system to quickly restore the voltage level after a disturbance to prevent voltage collapse; the third is power balance recovery capability, that is, the ability of the power system to quickly redistribute power to achieve a new stable state through scheduling and control strategies.

[0031] Among them, frequency support capability is a key link in evaluating the transient response characteristics of the power system, which is directly related to the instantaneous response speed and stability of the power system to load fluctuations.

[0032] Among them, inertia is an important physical basis for frequency support capability. Inertia refers to the kinetic energy stored in all rotating masses in the power system, among which the rotating masses are mainly generator rotors. Understandably, in the renewable energy power system, inertia also includes the inertia of new power sources such as wind and solar. This kinetic energy can be released when the system is disturbed, providing additional power support for the power system, slowing down the rate of frequency change, and providing time for real-time control measures.

[0033] Therefore, accurately assessing the inertia level of the power system is crucial to predicting and improving the system's transient active power support capability.

[0034] According to an embodiment of the present invention, an embodiment of a method for characterizing and evaluating the transient active support capability of a power system is provided, which mainly evaluates the inertia level of the power system. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that here.

[0035] In this embodiment, a method for characterizing and evaluating the transient active power support capability of a power system is provided. Figure 1 is a flow chart of a method for characterizing and evaluating the transient active support capability of a power system according to an embodiment of the present invention. It should be noted that if there are substantially the same results, this embodiment does not use Figure 1 The process sequence shown is limited. Figure 1 As shown, the process includes the following steps:

[0036] Step S101, collecting power data and frequency data of the power system.

[0037] Specifically, the operating status of the power system is obtained, the operating status of the power system is simulated using the PSASP simulation software, and the power data and frequency data of each area of ​​the power system are collected during the operation.

[0038] The operating state includes the frequency stable fluctuation state and the power disturbance state.

[0039] Specifically, in the daily operation of the power system, the frequency fluctuates slightly around the rated value of 50Hz. The stable frequency fluctuation state means that the frequency fluctuation range of the current power system is small, the maximum deviation of the frequency fluctuation does not exceed 0.05Hz, and the unit speed governor is not started. The power disturbance state means that the current power system is in a large disturbance state, the frequency fluctuation range is large, and the unit speed governor is operating.

[0040] The power data is the power change value, and the frequency data is the frequency change value.

[0041] It is understandable that when the operation state of the power system is different, the power change value and the frequency change value are different. For example, when the power system is in a state of stable frequency fluctuation, the power change value and the frequency change value are small, and when the power system is in a power disturbance state, the power change value and the frequency change value are large.

[0042] Step S102: Perform parameter identification on the power data and the frequency data based on the ARMAX power system identification model to obtain an inertia evaluation value.

[0043] Among them, the ARMAX model is a sub-regression moving average model, which is a time series prediction model used to describe the characteristics of time series data.

[0044] Taking power data as input and frequency data as output, ARMAX system identification technology is used to construct an ARMAX power system identification model from power data to frequency data; the frequency change rate after the step response of the ARMAX power system identification model is calculated; the frequency change rate after the step response is substituted into the swing equation to obtain the inertia time constant and obtain the inertia evaluation value.

[0045] Step S103, calculating the minimum safe inertia of the power system based on the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint of the power system.

[0046] The frequency change rate safety threshold constraint means that during the inertia response phase, the frequency change rate of the power system after the disturbance does not exceed the frequency change rate safety threshold.

[0047] Among them, the frequency deviation safety threshold constraint means that during the stage when inertia response and primary frequency regulation work together, the frequency change rate of the power system after the disturbance does not exceed the change rate safety threshold.

[0048] The safety inertia that satisfies the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint of the power system is calculated, and the minimum value of the safety inertia is taken to obtain the minimum safety inertia of the power system.

[0049] Step S104 , dividing the inertia interval into a high inertia interval, a low inertia interval and an insufficient inertia interval based on the minimum safe inertia.

[0050] Understandably, the minimum safe inertia is the bottom line of the power system inertia. When the inertia value of the power system is lower than the minimum safe inertia, it means that the current power system is difficult to maintain frequency stability and is prone to triggering the emergency defense line of the power grid. When the inertia value of the power system is higher than the minimum safe inertia, it means that the current power system is in a safe state. However, when the inertia value of the power system is higher than the minimum safe inertia but close to the minimum safe inertia, it means that although the current power system is in a safe state, it still has the risk of frequency instability.

[0051] Among them, the high inertia interval is the interval where the frequency is in a stable state, the low inertia interval is the interval where the frequency is close to an unbalanced state, and the insufficient inertia interval is the interval where the frequency is in an unbalanced state.

[0052] Specifically, the interval where the inertia is less than or equal to the minimum safe inertia is first divided into the insufficient inertia interval, and the interval where the inertia is greater than the minimum safe inertia is further divided into the high inertia interval and the low inertia interval. The interval within a certain range less than the minimum safe inertia is divided into the low inertia interval, and the rest of the interval is divided into the high inertia interval.

[0053] Step S105 , determining the inertia state of the current power system based on the inertia evaluation value, and issuing an inertia warning when the inertia evaluation value is in an inertia shortage interval.

[0054] The current inertia evaluation value is evaluated based on the inertia interval division result. The inertia evaluation value is compared with the high inertia interval, the low inertia interval and the insufficient inertia interval to determine the inertia interval in which the current power system inertia state is located.

[0055] Specifically, when the inertia evaluation value is less than or equal to the minimum safe inertia, the inertia state of the current power system is in an insufficient inertia state, and an inertia shortage warning is issued to adjust the operation data of the power system in time. When the inertia evaluation value is greater than the minimum safe inertia and is within a certain range of the minimum safe inertia, the inertia state of the current power system is in a low inertia state, and a low inertia warning is issued to pay attention to the operation of the power system, and if necessary, the operation data of the power system is adjusted so that the inertia state of the power system is in a high inertia state.

[0056] The method for characterizing and evaluating the transient active support capability of a power system provided in this embodiment uses the ARMAX parameter identification method to identify the system transfer function and obtain an inertia evaluation value. On this basis, the minimum safe inertia is determined based on the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint of the power system, and the minimum safe inertia is used to characterize the safety boundary of the minimum frequency regulation capability of the power system and divide the inertia interval. Combined with the inertia evaluation value, the inertia distribution characteristics of the power system can be evaluated more intuitively and meticulously, and the accuracy of the characterization and evaluation of the transient active support capability can be improved.

[0057] In this embodiment, a method for characterizing and evaluating the transient active power support capability of a power system is provided. Figure 2 is a flow chart of another method for characterizing and evaluating the transient active support capability of a power system according to an embodiment of the present invention. It should be noted that if there are substantially the same results, this embodiment does not use Figure 2 The process sequence shown is limited. Figure 2 As shown, the process includes the following steps:

[0058] Step S201: collecting power data and frequency data of each power system.

[0059] For details, please see Figure 1 Step S101 of the illustrated embodiment will not be described in detail here.

[0060] Step S202: Perform parameter identification on the power data and the frequency data based on the ARMAX power system model to obtain an inertia evaluation value.

[0061] In one implementation, the power system is in a state of stable frequency fluctuation. Based on the sliding window technology, multiple data windows are divided by a first preset time, and within the data windows, the first inertia values ​​of power data and frequency data are calculated based on the ARMAX power system model, and the first inertia values ​​of multiple data windows are averaged to obtain an inertia evaluation value.

[0062] Among them, the method for calculating the first inertia value includes: obtaining the sampling interval time in each data window, taking the power data as input and the frequency data as output according to the sampling interval time, using ARMAX system identification technology to construct an ARMAX power system identification model from power data to frequency data, performing parameter identification based on the ARMAX power system model, and reducing the order of the system frequency response transfer function obtained by ARMAX technology identification, thereby obtaining the inertia time constant of the power system and obtaining the first inertia value.

[0063] Specifically, based on the ARMAX power system model, parameter identification is performed to obtain the 2nd to 10th order discrete power system models, which are converted into continuous power system models to obtain a high-order continuous model of the regional frequency response model transfer function. Specifically, the discrete-time ARMAX power system model is converted into a continuous-time model using the d2c function in Matlab.

[0064] The continuous model of the power system is reduced to obtain a low-order model of the power system. Specifically, the model is converted into a balanced state space model, and unimportant states are identified and deleted under the state space model to form a descending system. The system is converted from the state space representation after reduction to a continuous time transfer function to obtain a low-order transfer function model that reflects the inertia transfer link of the system, and the inertia time constant of each low-order model of the power system is extracted, and the average value of the inertia time constant of each order model is calculated to obtain the first inertia value in the data window. Specifically, the ssdata, balreal, modred and ss2tf functions in Matlab are used to complete the above method.

[0065] In a specific example, a sliding window technique is used, with every 10 seconds as a data window, a data sampling interval of 0.01 seconds, and an inertia evaluation updated once a second.

[0066] In another implementation, the power system is in a power disturbance state. A sampling interval is obtained, and within a second preset time after the disturbance occurs, a first inertia value of power data and frequency data is calculated based on the ARMAX power system model according to the sampling interval, and the first inertia value is used as the inertia evaluation value.

[0067] The method for calculating the first inertia value is the same as the above implementation, and will not be described again here.

[0068] In a specific example, the evaluation is performed before a frequency regulation action, that is, within 250 milliseconds after the disturbance. The power system is in the inertia response stage at this stage. The data sampling interval is 0.01 seconds, and the inertia evaluation is updated once per second.

[0069] Among them, the existing inertia estimation methods based on measurement data mostly rely on large disturbance events, which makes it difficult to effectively monitor and warn the inertia of the power system in real time when the frequency fluctuates steadily. In this implementation, inertia evaluation is performed in two scenarios, namely, steady-state frequency fluctuation and large disturbance. It can comprehensively monitor the steady-state frequency fluctuation and large disturbance to effectively monitor the power inertia. Combined with ARMAX parameter identification technology, it can effectively identify the transfer function of the system, and obtain the key part of the inertia response through model simplification, and then accurately calculate the inertia time constant, providing a basis for the calculation of subsequent inertia evaluation values.

[0070] Step S203, calculating the minimum safe inertia of the power system based on the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint of the power system.

[0071] The minimum safe inertia under the frequency change rate safety threshold constraint of the power system and the minimum safe inertia under the frequency deviation safety threshold constraint are calculated respectively, and the maximum value of the two minimum safe inertias is taken to obtain the minimum safe inertia of the power system.

[0072] Specifically, the above step S203 includes:

[0073] Step S2031, calculating the minimum first safety inertia based on the frequency change rate safety threshold constraint of the power system.

[0074] See also Figure 3 , Figure 3 FIG. 1 is a schematic diagram of power during the frequency dynamic response process according to an embodiment of the present invention. Figure 3 As shown, the first stage is the inertia response stage t 0 ~t d The second stage is the stage of inertia response and primary frequency modulation. d ~t nadir . Figure 3The relationship curves between time and frequency, time and inertia corresponding active power, and time and primary frequency modulation active power are shown in Fig. 0 ~t d , solve the minimum first safety inertia of the power system considering the frequency change rate safety threshold constraint. The frequency change rate of the power system after the disturbance does not exceed the change rate safety threshold as the constraint condition. At this stage, the frequency deviation does not exceed the governor action dead zone, and the unit primary frequency regulation function does not act.

[0075] The frequency dynamic process at the initial stage of disturbance is analyzed based on the generator rotor motion equation, as shown in the following formula:

[0076]

[0077] Among them, ΔP(t) is the total unbalanced power of the power system, Δf(t) is the frequency deviation of the power system after the disturbance, and f 0 is the rated frequency of the power system, and D is the damping coefficient of the power system.

[0078] Integrate both sides of the generator rotor motion equation simultaneously, and the inertia time constant of the power system is expressed as:

[0079]

[0080] Assume that the frequency change rate of the power system after the disturbance does not exceed the frequency change rate safety threshold RoCoF max , the above formula is further simplified to obtain the first safety inertia required by the power system in the first stage, which satisfies the following formula:

[0081]

[0082] in, is the first safety inertia, ΔP 0 is the initial unbalanced power of the power system, Δf d It is the frequency regulation dead zone of the power system.

[0083] According to the above formula, take the minimum value of the first safety inertia to obtain the minimum first safety inertia.

[0084] Step S2032, calculating the minimum second safety inertia based on the frequency deviation safety threshold constraint of the power system.

[0085] Continue reading Figure 3 , the stage of inertia response and primary frequency modulation acting together t d ~t nadir, solve the minimum second safety inertia considering the frequency deviation safety threshold constraint of the power system. The frequency change rate of the power system after the disturbance does not exceed the safety threshold of the change rate as a constraint. At this stage, the frequency deviation of the power system exceeds the dead zone of the speed regulator, and the speed regulator participates in the primary frequency regulation.

[0086] Assuming that the active output of the speed regulator is linear at this stage, the power adjustment rate of the power system is R s , speed regulator action time t d The time t when the frequency reaches the lowest point nadir Satisfy the following formula:

[0087]

[0088] Based on the above linear assumptions, we can integrate the equations to get:

[0089]

[0090]

[0091]

[0092] Substituting the above formula into The second safety inertia of the power system can be obtained as:

[0093]

[0094] Set the speed regulator action time t d The time t when the frequency reaches the lowest point nadir Substituting into the above formula, the lowest frequency deviation is obtained as:

[0095]

[0096] When the power system faces an N-1 fault shock, the system inertia response and primary frequency regulation work together, and the frequency deviation of the power system will be strictly controlled within the safety threshold Δf of the frequency deviation of the power system. max To ensure that the store system meets the frequency deviation requirements, Δf max Substituting the above formula, the second safety inertia required by the second-stage power system is calculated to satisfy the following formula:

[0097]

[0098] in, is the second safety inertia.

[0099] Step S2033, taking the maximum value of the minimum first safety inertia and the minimum second safety inertia to obtain the minimum safety inertia.

[0100] Considering the entire frequency regulation dynamic process, the maximum values ​​of the minimum first safety inertia and the minimum second safety inertia are calculated, and the minimum safety inertia of the power system is obtained as:

[0101]

[0102] In this implementation, in order to quantify the frequency safety and stability risk of the power system after suffering an unbalanced power disturbance, the system inertia response is analyzed, and the minimum safe inertia under the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint is proposed as the inertia warning indicator, which can improve the accuracy of the inertia warning.

[0103] Step S204 : dividing the inertia interval into a high inertia interval, a low inertia interval and an insufficient inertia interval based on the minimum safe inertia.

[0104] Specifically, the above step S204 includes:

[0105] Step S2041, constructing an inertia safety margin index based on the minimum safety inertia.

[0106] In order to quantify the frequency safety and stability risk of the power system after suffering an unbalanced power disturbance, the inertia safety margin index is defined based on the minimum safe inertia and analyzed from the perspective of system inertia response, comparing the distance between the current system inertia and its safety boundary:

[0107]

[0108] Among them, ISM is the inertia safety margin index, H sys is the inertia value of the power system.

[0109] Step S2042: classify the inertia region where the inertia safety margin is less than or equal to zero as an inertia shortage region.

[0110] The inertia interval where the inertia safety margin is less than or equal to zero, that is, the inertia interval where the inertia value is less than the minimum safe inertia, is divided into the insufficient inertia interval.

[0111] Step S2043: classify the inertia interval in which the inertia safety margin is greater than zero and less than or equal to the first preset safety margin value as a low inertia interval.

[0112] An inertia interval in which the inertia safety margin is greater than zero and less than or equal to a first preset safety margin value, that is, an inertia interval within a certain range in which the inertia value is greater than the minimum safety inertia and less than the minimum safety inertia, is divided into a low inertia interval.

[0113] Step S2044: divide the inertia region where the inertia safety margin is greater than the first preset safety margin value into a high inertia interval.

[0114] An inertia region where the inertia safety margin is greater than a first preset safety margin value, that is, an inertia interval within a certain range where the inertia value is greater than the minimum safe inertia, is divided into a high inertia interval.

[0115] The first preset safety margin value is greater than zero. The first preset safety margin value may be determined according to provincial or regional power grids.

[0116] See also Figure 4 , Figure 4 Schematic diagram of inertia interval according to an embodiment of the present invention. Figure 4 As shown, the three intervals from top to bottom are the high inertia interval, the low inertia interval and the insufficient inertia interval.

[0117] Step S205 , determining the inertia state of the current power system based on the inertia evaluation value, and issuing an inertia warning when the inertia evaluation value is in an inertia shortage interval.

[0118] The current inertia safety margin of the inertia evaluation value is calculated based on the inertia safety margin indicator, and the current inertia safety margin is calculated to determine the inertia state of the current power system.

[0119] When the power system encounters disturbances in a low inertia or critical inertia state, it is difficult for the system to maintain frequency stability, and it is easy to trigger the emergency defense line of the power grid. Specifically, if the current inertia safety margin is less than or equal to zero, the inertia state of the current power system is in an insufficient inertia state, and an inertia shortage warning is issued to adjust the operating data of the power system in time. If the current inertia safety margin is greater than zero and less than or equal to the first preset safety margin value, the inertia state of the current power system is in a low inertia state, and a low inertia warning is issued to pay attention to the operation of the power system, and if necessary, adjust the operating data of the power system so that the inertia state of the power system is in a high inertia state.

[0120] Among them, the inertia level is obtained based on the current flow section assessment. Once the load and other conditions of the power system change, resulting in the adjustment of the power system operation state, the inertia level of the power system will also fluctuate, and the inertia of each inertia partition will also be adjusted accordingly. When the power system is operating at a low inertia level, if the operating state changes, it is necessary to redefine the inertia boundaries for safe and stable operation of the system and its partitions.

[0121] Furthermore, the output power of the new energy unit is related to the external system state, such as voltage and other operating conditions. When the system operating state changes, the output power of the unit will also change, which will affect the equivalent inertia of the power system. In order to analyze the impact of the new energy unit on the system inertia, the impact coefficient Q of the new energy unit is defined as follows:

[0122]

[0123] Among them, Hsys Represents the effective inertia of the system, H g Indicates the inertia provided by the synchronous unit. The greater the impact of the new energy unit on the system inertia, the greater the value of parameter Q.

[0124] This influence coefficient is used to measure the contribution of new energy units to the system inertia level. In power systems with different penetration rates of new energy, the results of the inertia evaluation method of the present invention and the inertia evaluation method directly calculated by the swing equation are compared. It is found that when there is no wind power access, the results of the two evaluation methods are similar, and both are slightly different from the theoretical inertia of the system; when a high proportion of wind power is connected, the evaluation results of the two methods are different from the theoretical inertia of the system, but the error of the proposed method is smaller. At this time, the influence coefficient Q of the new energy unit is used to measure its impact on the system inertia level. When wind power is connected, the Q value becomes larger. At this time, when a disturbance occurs, the terminal voltage of the wind turbine also changes, and the power output to the system through the converter will also change, which will affect the inertia response of the system. Therefore, using system measurement data for inertia evaluation can better take into account the inertia response of the new energy unit to the system.

[0125] The transient active support capability characterization and evaluation method of the power system provided in this embodiment performs inertia evaluation in two scenarios: steady-state frequency fluctuation and large disturbance. It can comprehensively consider steady-state frequency fluctuation and large disturbance to effectively monitor power inertia. Combined with ARMAX parameter identification technology, it can effectively identify the transfer function of the system, and obtain the key part of the inertia response through model simplification, and then accurately calculate the inertia time constant, providing a basis for the calculation of subsequent inertia evaluation values; introducing inertia safety margin as an indicator for evaluating inertia, safety warnings can more intuitively help power grid operators understand the current inertia level of the system, and issue warnings in time when inertia is short, thereby effectively avoiding the risk of frequency instability.

[0126] In this embodiment, a device for characterizing and evaluating the transient active support capacity of a power system is also provided, and the device is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware for a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0127] This embodiment provides a device for characterizing and evaluating the transient active power support capability of a power system. Figure 5 As shown, Figure 5 1 is a structural block diagram of a device for characterizing and evaluating the transient active power support capability of a power system according to an embodiment of the present invention, wherein the device for characterizing and evaluating the transient active power support capability of a power system comprises:

[0128] The acquisition module 501 is used to acquire power data and frequency data of the power system.

[0129] The identification module 502 is used to perform parameter identification on the power data and the frequency data based on the ARMAX power system model to obtain an inertia evaluation value.

[0130] The calculation module 503 is used to calculate the minimum safe inertia of the power system based on the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint of the power system.

[0131] The division module 504 is used to divide the inertia interval into a high inertia interval, a low inertia interval and an insufficient inertia interval based on the minimum safe inertia.

[0132] The evaluation module 505 is used to determine the inertia state of the current power system based on the inertia evaluation value, and to issue an inertia warning when the inertia evaluation value is in an inertia shortage interval.

[0133] The further functional description of each of the above modules is the same as that of the above corresponding embodiments and will not be repeated here.

[0134] The transient active support capability characterization and evaluation device of the power system in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0135] The embodiment of the present invention also provides a computer device having the above Figure 5 The device shown is for characterizing and evaluating the transient active support capability of a power system.

[0136] See also Figure 6 , Figure 6 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Figure 6As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 6 A processor 10 is taken as an example.

[0137] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0138] The memory 20 stores instructions executable by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiment.

[0139] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0140] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0141] The computer device also includes an input device 30 and an output device 40. The processor 10, the memory 20, the input device 30 and the output device 40 may be connected via a bus or other means. Figure 6 The example of connecting through bus is taken in the following.

[0142] The input device 30 can receive input digital or character information, and generate key signal input related to the user settings and function control of the computer device, such as a touch screen, a keypad, a mouse, a track pad, a touch pad, an indicator bar, one or more mouse buttons, a trackball, a joystick, etc. The output device 40 may include a display device, an auxiliary lighting device (e.g., an LED) and a tactile feedback device (e.g., a vibration motor), etc. The above-mentioned display device includes but is not limited to a liquid crystal display, a light emitting diode, a display and a plasma display. In some optional embodiments, the display device can be a touch screen.

[0143] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0144] A part of the present invention may be applied as a computer program product, such as a computer program instruction, which, when executed by a computer, can call or provide the method and / or technical solution according to the present invention through the operation of the computer. Those skilled in the art should understand that the existence of the computer program instruction in a computer-readable medium includes, but is not limited to, a source file, an executable file, an installation package file, etc., and accordingly, the way in which the computer program instruction is executed by the computer includes, but is not limited to: the computer directly executes the instruction, or the computer compiles the instruction and then executes the corresponding compiled program, or the computer reads and executes the instruction, or the computer reads and installs the instruction and then executes the corresponding installed program. Here, the computer-readable medium may be any available computer-readable storage medium or communication medium accessible to the computer.

[0145] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for characterizing and evaluating the transient active support capability of a power system, characterized in that: The method comprises: Collect power data and frequency data of the power system; Perform parameter identification on the power data and the frequency data based on an ARMAX power system model to obtain an inertia evaluation value; Calculating the minimum safe inertia of the power system based on a frequency change rate safety threshold constraint and a frequency deviation safety threshold constraint of the power system; Based on the minimum safe inertia, the inertia interval is divided into a high inertia interval, a low inertia interval and an insufficient inertia interval; The inertia state of the current power system is determined based on the inertia evaluation value, and an inertia warning is performed when the inertia evaluation value is in the inertia shortage interval.

2. The method for characterizing and evaluating the transient active support capability of a power system according to claim 1, characterized in that: The performing parameter identification on the power data and the frequency data based on the ARMAX power system identification model to obtain the inertia evaluation value includes: When the power system is in a state of stable frequency fluctuation, a plurality of data windows are divided according to a first preset time based on a sliding window technology; In the data window, calculating a first inertia value of the power data and the frequency data based on the ARMAX power system identification model; An average value of the first inertia values ​​of a plurality of data windows is calculated to obtain the inertia evaluation value.

3. The method for characterizing and evaluating the transient active power support capability of a power system according to claim 1, characterized in that: The performing parameter identification on the power data and the frequency data based on the ARMAX power system identification model to obtain the inertia evaluation value includes: When the power system is in a power disturbance state, within a second preset time when the disturbance occurs, calculating the first inertia value of the power data and the frequency data based on the ARMAX power system identification model; The first inertia value is used as the inertia estimation value.

4. The method for characterizing and evaluating the transient active support capability of a power system according to claim 2 or 3, characterized in that: The calculating the first inertia value of the power data and the frequency data based on the ARMAX power system identification model comprises: Get the sampling interval time; According to the sampling interval, based on the ARMAX power system identification model, parameter identification is performed on the power data and the frequency data to obtain a 2nd to 10th order power system discrete model; Converting the power system discrete model into a power system continuous model; Performing order reduction processing on the continuous model of the power system to obtain a low-order model of the power system, and extracting the inertia time constant of each low-order model of the power system; An average value of the inertia time constant is calculated to obtain the first inertia value.

5. The method for characterizing and evaluating the transient active power support capability of a power system according to claim 1, characterized in that: The calculating of the minimum safe inertia of the power system based on the frequency change rate safety threshold constraint and the frequency deviation safety threshold constraint of the power system comprises: The minimum first safety inertia is calculated based on the frequency change rate safety threshold constraint of the power system, wherein the frequency change rate safety threshold constraint of the power system is: Among them, the is the first safety inertia, ΔP0 is the initial unbalanced power of the power system, and Δf d is the frequency regulation dead zone of the power system, f0 is the rated frequency of the power system, D is the damping coefficient of the power system, and RoCoF max is a safety threshold value of the frequency change rate of the power system; The minimum second safety inertia is calculated based on the frequency deviation safety threshold constraint of the power system, wherein the frequency deviation safety threshold constraint of the power system is: Among them, the is the second safety inertia, the Δf max is the safety threshold of the frequency deviation of the power system, the R s is the power adjustment rate of the power system; The minimum safety inertia is obtained by taking the maximum value of the minimum first safety inertia and the minimum second safety inertia.

6. The method for characterizing and evaluating the transient active power support capability of a power system according to claim 1, characterized in that: The dividing the inertia interval into a high inertia interval, a low inertia interval and an insufficient inertia interval based on the minimum safe inertia comprises: constructing an inertia safety margin index based on the minimum safe inertia; dividing an inertia region where the inertia safety margin is less than or equal to zero as the insufficient inertia interval; dividing an inertia region in which the inertia safety margin is greater than zero and less than or equal to a first preset safety margin value into the low inertia interval; An inertia region in which the inertia safety margin is greater than a first preset safety margin value is divided into the high inertia interval, wherein the first preset safety margin value is greater than zero.

7. The method for characterizing and evaluating the transient active power support capability of a power system according to claim 6, characterized in that: Determining the inertia state of the current power system based on the inertia evaluation value includes: Calculating a current inertia safety margin of the inertia evaluation value based on an inertia safety margin indicator; The current inertia safety margin is calculated to determine the current inertia state of the electric power system.

8. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the method for characterizing and evaluating the transient active support capability of a power system according to any one of claims 1 to 7 by executing the computer instructions.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the method for characterizing and evaluating the transient active support capability of a power system according to any one of claims 1 to 7.

10. A computer program product, characterized in that It comprises computer instructions, and the computer instructions are used to enable a computer to execute the method for characterizing and evaluating the transient active support capability of a power system according to any one of claims 1 to 7.

Images