Power system power deficiency estimation method and device, terminal equipment and storage medium

Abstract

The application discloses a power system power shortage estimation method and device, terminal equipment and a storage medium. The method comprises the following steps: constructing a local frequency variation model of a generator in a power system; sampling the local frequency of the generator in the power system to obtain a local frequency variation time sequence; extracting the coefficient of a linear component of the local frequency variation according to the local frequency variation model and the local frequency variation time sequence through least square fitting; and calculating a power system power shortage estimation value according to the coefficient of the linear component of the local frequency variation and the total inertia of the power system. The application can quickly estimate the power system power shortage without real-time communication.

Description

Technical Field

[0001] This invention relates to the field of power grid technology, and in particular to a method, apparatus, terminal equipment and storage medium for estimating power deficit in power systems. Background Technology

[0002] In recent years, new energy power generation has been vigorously developed due to its advantages such as cleanliness and renewability. With the increasing proportion of converter-interfaced generators (CIGs), the inertia level of the power grid is constantly decreasing, and frequency stability issues are becoming increasingly prominent. Converter-interfaced generators have the advantages of flexible control and rapid response. Utilizing this characteristic, the output of converter-interfaced generators can be quickly adjusted to reduce power deficit in the system, thereby reducing system frequency deviation and improving system frequency stability.

[0003] To achieve this control structure, it is necessary to quickly estimate the power deficit of the power system. Therefore, how to quickly estimate the power deficit of the power system is an urgent problem to be solved. Summary of the Invention

[0004] This invention provides a method, apparatus, terminal equipment, and storage medium for estimating power deficit in a power system, which can quickly estimate power deficit in a power system without real-time communication.

[0005] An embodiment of the present invention provides a method for estimating power deficit in a power system, comprising:

[0006] Construct a model of the local frequency variation of generators in a power system;

[0007] The local frequency of generators in the power system is sampled to obtain the time series of local frequency changes;

[0008] Based on the local frequency change model and the local frequency change time series, the coefficients of the linear component of the local frequency change are extracted by least squares fitting.

[0009] The estimated power deficit of the power system is calculated based on the coefficients of the linear component of the local frequency variation and the total inertia of the power system.

[0010] Furthermore, the local frequency change model is specifically as follows:

[0011]

[0012] Where Δωi is the frequency change of the i-th generator; P d For power deficit in the power system; H COI α is the total inertia of the power system; t is the sampling time; ik β k, These represent the amplitude, frequency, and phase angle corresponding to the k-th electromechanical mode obtained by linear combination; n is the number of generators in the power system; and the subscript i indicates the i-th generator.

[0013] Furthermore, based on the local frequency change model and the local frequency change time series, the coefficients of the linear component of the local frequency change are extracted by least squares fitting, including:

[0014] Based on the local frequency change model and the local frequency change time series, the following least squares fitting function is constructed:

[0015]

[0016] Solving the least squares fitting function yields the coefficients of the linear component of the local frequency change.

[0017] Where m is the number of sampling points for the generator's local frequency; y j t represents the local frequency change obtained at the j-th sampling point; j is the sampling time of the j-th sampling point; l is the coefficient of the linear component of the local frequency change to be determined.

[0018] Furthermore, the step of calculating the estimated power system power deficit based on the linear component of the local frequency change and the total inertia of the power system includes:

[0019] The estimated power deficit of the power system is calculated using the following formula:

[0020]

[0021] in, This is an estimated value for the power deficit in the power system.

[0022] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments;

[0023] One embodiment of the present invention provides a power system power deficit estimation device, including: a model building module, a sampling module, a coefficient calculation module, and a power deficit determination module;

[0024] The model building module is used to build a model of the local frequency variation of generators in a power system.

[0025] The sampling module is used to sample the local frequency of the generator in the power system to obtain the time series of local frequency changes.

[0026] The coefficient calculation module is used to extract the coefficients of the linear component of the local frequency change by least squares fitting based on the local frequency change model and the local frequency change time series.

[0027] The power deficit determination module is used to calculate the estimated power deficit of the power system based on the coefficient of the linear component of the local frequency change and the total inertia of the power system.

[0028] Furthermore, the local frequency change model constructed by the model building module is specifically as follows:

[0029]

[0030] Where Δωi is the frequency change of the i-th generator; P d For power deficit in the power system; H COI α is the total inertia of the power system; t is the sampling time; ik β k , These represent the amplitude, frequency, and phase angle corresponding to the k-th electromechanical mode obtained by linear combination; n is the number of generators in the power system; and the subscript i indicates the i-th generator.

[0031] Furthermore, the coefficient calculation module, based on the local frequency change model and the local frequency change time series, extracts the coefficients of the linear component of the local frequency change through least squares fitting, including:

[0032] Based on the local frequency change model and the local frequency change time series, the following least squares fitting function is constructed:

[0033]

[0034] Solving the least squares fitting function yields the coefficients of the linear component of the local frequency change.

[0035] Where m is the number of sampling points for the generator's local frequency; y j t represents the local frequency change obtained at the j-th sampling point; j is the sampling time of the j-th sampling point; l is the coefficient of the linear component of the local frequency change to be determined.

[0036] Furthermore, the power deficit determination module calculates an estimated power deficit value for the power system based on the linear component of the local frequency change and the total inertia of the power system, including:

[0037] The estimated power deficit of the power system is calculated using the following formula:

[0038]

[0039] in, This is an estimated value for the power deficit in the power system.

[0040] Based on the above method embodiments, the present invention provides corresponding terminal device embodiments;

[0041] One embodiment of the present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the power system power deficit estimation method according to any one of the present invention.

[0042] Based on the above method embodiments, the present invention provides corresponding storage medium embodiments;

[0043] One embodiment of the present invention provides a storage medium comprising a stored computer program, wherein, when the computer program is executed, it controls the device where the storage medium is located to execute the power system power deficit estimation method according to any one of the present invention.

[0044] The following beneficial effects can be achieved by implementing the embodiments of the present invention:

[0045] This invention provides a method, apparatus, terminal equipment, and storage medium for estimating power system power deficit. Power system power deficit can be obtained by multiplying the total system inertia by the power system COI frequency change rate. Given the total system inertia, power deficit estimation relies on the rapid calculation of the COI frequency change rate (ROCOF). In the initial stage of a power system disturbance, the linear component of the local frequency change is equal to the system COI frequency change. Therefore, the coefficient of the linear component of the local frequency change can be directly obtained as the power system COI frequency change rate, thereby calculating the power system power deficit. In this invention, the method solves for the coefficient of the linear component of the local frequency change based on a local frequency change model. Then, based on the coefficient of the linear component of the local frequency change and the total system inertia, the estimated power system power deficit is calculated. The entire process does not require real-time communication and can quickly estimate the power system COI frequency change rate to obtain the system power deficit. This is beneficial for fully utilizing the rapid power regulation capability of CIGs and improving system frequency stability. Attached Figure Description

[0046] Figure 1 This is a flowchart illustrating a power deficit estimation method for a power system according to an embodiment of the present invention.

[0047] Figure 2 This is a schematic diagram of a power system topology provided in an embodiment of the present invention.

[0048] Figure 3 The dynamic response process of generator No. 5 after generator No. 9 is disconnected from the power system.

[0049] Figure 4 The dynamic response process of generator No. 8 after a sudden increase of 4 p.u. in the active power of the load at node 15 of the power system.

[0050] Figure 5 This is a schematic diagram of the structure of a power system power deficit estimation device provided in an embodiment of the present invention. Detailed Implementation

[0051] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0052] like Figure 1 As shown, one embodiment of the present invention provides a method for estimating power deficit in a power system, comprising at least:

[0053] Step S101: Construct a model of the local frequency variation of generators in the power system.

[0054] Step S102: Sample the local frequency of the generator in the power system to obtain the time series of local frequency changes.

[0055] Step S103: Based on the local frequency change model and the local frequency change time series, extract the coefficients of the linear component of the local frequency change by least squares fitting.

[0056] Step S104: Calculate the estimated power deficit of the power system based on the coefficient of the linear component of the local frequency change and the total inertia of the power system.

[0057] For step S101, a mathematical model is specifically established for the initial COI of the multi-machine power system under disturbance and the frequency changes of each generator. The power system COI swing equation is as follows:

[0058]

[0059]

[0060]

[0061] Among them, H COI The total inertia of the power system; ωCOI H is the center frequency of the power system inertia. i Let ω be the inertia constant of the i-th generator; i The frequency of the i-th generator; P mi and P ei Let represent the mechanical power and electromagnetic power of the i-th generator, respectively; n is the number of generators in the power system.

[0062] For a very short period after the disturbance occurs, it can be assumed that the governor has not yet started, and the mechanical power of the generator can be considered constant. Therefore, (1) can be rewritten in the following form:

[0063]

[0064] Where Δ represents the change, P d This is for the power deficit in the power system.

[0065] Integrating both sides of equation (2) from time 0 to time t, we can obtain the model of the change in the COI frequency of the system:

[0066]

[0067] Taking the nth generator as the reference unit, the state equation of the n-generator system considering only the rotor dynamics is:

[0068]

[0069] x=[Δδ 1n …Δδ (n-1)n Δω 1n …Δω (n-1)n ] T

[0070]

[0071]

[0072]

[0073] Where, δ ij ω represents the power angle difference between generators i and j; ij E represents the frequency difference between generators i and j; i Let G be the internal electromotive force of the i-th generator; ij and B ij These are the transfer conductance and transfer susceptance between generators i and j, respectively; the subscript (0) indicates the initial steady-state operating point.

[0074] Matrix A has n-1 pairs of conjugate complex roots, corresponding to n-1 electromechanical modes of the system. According to the solution of equation (4), the difference between the frequency change of each generator and the frequency change of the reference generator can be expressed as a linear combination of n-1 electromechanical modes:

[0075]

[0076] Among them, a ik and b ik β is the amplitude corresponding to the k-th electromechanical mode obtained by linear combination. k The frequency corresponding to the k-th electromechanical mode is obtained by linear combination; the subscript i indicates the i-th generator.

[0077] Combining equations (5) and (3), we get:

[0078]

[0079] Adding equation (6) to equation (5), we obtain the expression for the frequency change of any generator (i.e., the local frequency change model of the generator in the power system described in this invention):

[0080]

[0081] Where, α ik β k , These represent the amplitude, frequency, and phase angle corresponding to the k-th electromechanical mode obtained by linear combination.

[0082] Furthermore, as can be seen from (7) and (3), in the initial stage of system disturbance, the linear component of the local frequency change is the same as the COI frequency change.

[0083] For step S102, the local frequency is sampled, and the number of sampling points is m, to obtain the time series of local frequency change {(t1,y1), (t2,y2), ..., (tm,ym)}, where yi represents the local frequency change obtained at the i-th sampling point;

[0084] For step S103, specifically, based on the sampled values ​​of S2, the linear component of the local frequency change is extracted using least squares fitting.

[0085] Specifically, according to equation (8), a least-squares fitting function is constructed, and the following optimization problem is solved to obtain the linear component lt of the local frequency change:

[0086]

[0087] For step S104, specifically, the estimated power deficit value of the power system. It is given by the following formula:

[0088]

[0089] Where l is the optimal solution obtained in S3.

[0090] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the present invention will be described below using examples from real-world scenarios.

[0091] Please see Figure 2 , Figure 2 This is a schematic diagram of the New England 39-node system under test. The system has a rated frequency of 60Hz and a base capacity of 100MVA.

[0092] Please see Figure 3 , Figure 3 The frequency response of generator 5 after generator 9 is disconnected from the power system is shown. It can be seen that the fitted local frequency (dashed line) is very close to the actual local frequency (solid line). Furthermore, the linear component of the extracted local frequency (dotted-dash line) is almost identical to the COI frequency (double-dotted-dash line). This confirms that the proposed method achieves rapid estimation of the COI frequency with acceptable accuracy. The orange dashed line in the figure represents the COI frequency estimation curve obtained by approximating the COI frequency curve using the line connecting every two adjacent inflection points of the local frequency. It can be seen that, compared to the method proposed in this invention, this method has a larger deviation from the actual COI frequency. Moreover, the rapid power deficit estimation method proposed in this invention uses a time series sampling frequency of 1 kHz and a time window length of 0.4 seconds, while the second frequency inflection point of generator 5 occurs approximately 0.67 seconds after the system is disturbed. Therefore, the method proposed in this invention has a shorter processing time.

[0093] Table 1 shows the estimated power deficit after the power system disconnects generator No. 9. As shown in Table 1, the coefficients of the linear components of the frequencies of different generators are very close, verifying the correctness of the proposed method. Furthermore, the power deficit estimated from each generator is very close to the actual power deficit, with an error generally within 10%.

[0094] Table 1

[0095]

[0096] like Figure 4 As shown, Figure 4 The figure shows the dynamic response of generator No. 8 after a sudden increase of 4 p.u. in the active power of the load at node 15 of the power system. As can be seen from the figure, the fitted curve can well approximate the generator frequency curve, and the linear component extracted from the local frequency change almost coincides with the COI frequency curve.

[0097] As shown in Table 2, the system power deficit estimation results are based on the frequency information of each generator in the system after a sudden change in node 15 of the test system. As the table shows, the estimation error is within an acceptable range when the node load changes abruptly, proving that the power deficit estimation method for power systems provided by this invention has high application value.

[0098] Table 2

[0099]

[0100] Based on the above method embodiments, the present invention provides a corresponding apparatus embodiment;

[0101] One embodiment of the present invention provides a power system power deficit estimation device, including: a model building module, a sampling module, a coefficient calculation module, and a power deficit determination module;

[0102] The model building module is used to build a model of the local frequency variation of generators in a power system.

[0103] The sampling module is used to sample the local frequency of the generator in the power system to obtain the time series of local frequency changes.

[0104] The coefficient calculation module is used to extract the coefficients of the linear component of the local frequency change by least squares fitting based on the local frequency change model and the local frequency change time series.

[0105] The power deficit determination module is used to calculate the estimated power deficit of the power system based on the coefficient of the linear component of the local frequency change and the total inertia of the power system.

[0106] In a preferred embodiment, the local frequency change model constructed by the model building module is specifically as follows:

[0107]

[0108] Where Δωi is the frequency change of the i-th generator; P d For power deficit in the power system; H COI α is the total inertia of the power system; t is time; α ik β k , These represent the amplitude, frequency, and phase angle corresponding to the k-th electromechanical mode obtained by linear combination; n is the number of generators in the power system; and the subscript i indicates the i-th generator.

[0109] In a preferred embodiment, the coefficient calculation module extracts the coefficients of the linear component of the local frequency change by least squares fitting based on the local frequency change model and the local frequency change time series, including:

[0110] Based on the local frequency change model and the local frequency change time series, the following least squares fitting function is constructed:

[0111]

[0112] Solving the least squares fitting function yields the coefficients of the linear component of the local frequency change.

[0113] Where m is the number of sampling points for the generator's local frequency; y j t represents the local frequency change obtained at the j-th sampling point; j is the sampling time of the j-th sampling point; l is the coefficient of the linear component of the local frequency change to be determined.

[0114] In a preferred embodiment, the power deficit determination module calculates an estimated power deficit value for the power system based on the linear component of the local frequency change and the total inertia of the power system, including:

[0115] The estimated power deficit of the power system is calculated using the following formula:

[0116]

[0117] in, This is an estimated value for the power deficit in the power system.

[0118] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0119] Those skilled in the art will clearly understand that, for convenience and simplicity, the specific working process of the device described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0120] Based on the above method embodiments, the present invention provides corresponding terminal device embodiments;

[0121] One embodiment of the present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the power system power deficit estimation method according to any one of the present invention.

[0122] The terminal device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0123] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0124] The memory can be used to store the computer program. The processor implements various functions of the terminal device by running or executing the computer program stored in the memory and calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function, etc.; the data storage area may store data created based on the use of the mobile phone, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0125] Based on the above method embodiments, the present invention provides corresponding storage medium embodiments;

[0126] One embodiment of the present invention provides a storage medium comprising a stored computer program, wherein, when the computer program is executed, it controls the device where the storage medium is located to execute the power system power deficit estimation method according to any one of the present invention.

[0127] The storage medium is a computer-readable storage medium, and the computer program is stored in the computer-readable storage medium. When executed by a processor, the computer program can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0128] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for estimating power deficit in a power system, characterized in that, include: A model of local frequency variation of generators in a power system is constructed; wherein, the local frequency variation model is specifically: ; Let be the frequency change of the i-th generator; P d This is due to the power deficit in the power system. H COI The total inertia of the power system is t; the sampling time is t. , , These represent the amplitude, frequency, and phase angle corresponding to the k-th electromechanical mode obtained by linear combination; n This represents the number of generators in the power system; the subscript i indicates the i-th generator. The local frequency of generators in the power system is sampled to obtain the time series of local frequency changes; Based on the local frequency change model and the local frequency change time series, the coefficients of the linear component of the local frequency change are extracted by least squares fitting. The estimated power deficit of the power system is calculated using the following formula based on the coefficients of the linear component of the local frequency variation and the total inertia of the power system: ;in, This is an estimated value for the power deficit in the power system; These are the coefficients of the linear component of the local frequency variation.

2. The power system power deficit estimation method as described in claim 1, characterized in that, Based on the local frequency change model and the local frequency change time series, the coefficients of the linear component of the local frequency change are extracted by least squares fitting, including: Based on the local frequency change model and the local frequency change time series, the following least squares fitting function is constructed: ； Solving the least squares fitting function yields the coefficients of the linear component of the local frequency change. Where m is the number of sampling points for the local frequency of the generator; This represents the local frequency change obtained at the j-th sampling point; The sampling time is the sampling time for the j-th sampling point.

3. A power system power deficit estimation device, characterized in that, include: The module includes a model building module, a sampling module, a coefficient calculation module, and a power deficit determination module. The model building module is used to build a local frequency variation model of generators in a power system; wherein, the local frequency variation model specifically includes: ; Let be the frequency change of the i-th generator; P d This is due to the power deficit in the power system. H COI The total inertia of the power system is t; the sampling time is t. , , These represent the amplitude, frequency, and phase angle corresponding to the k-th electromechanical mode obtained by linear combination; n This represents the number of generators in the power system; the subscript i indicates the i-th generator. The sampling module is used to sample the local frequency of the generator in the power system to obtain the time series of local frequency changes. The coefficient calculation module is used to extract the coefficients of the linear component of the local frequency change by least squares fitting based on the local frequency change model and the local frequency change time series. The power deficit determination module is used to calculate the estimated power deficit of the power system based on the coefficient of the linear component of the local frequency change and the total inertia of the power system using the following formula: ;in, This is an estimated value for the power deficit in the power system; These are the coefficients of the linear component of the local frequency variation.

4. The power system power deficit estimation device as described in claim 3, characterized in that, The coefficient calculation module, based on the local frequency change model and the local frequency change time series, extracts the coefficients of the linear component of the local frequency change through least squares fitting, including: Based on the local frequency change model and the local frequency change time series, the following least squares fitting function is constructed: ； Solving the least squares fitting function yields the coefficients of the linear component of the local frequency change. Where m is the number of sampling points for the local frequency of the generator; This represents the local frequency change obtained at the j-th sampling point; The sampling time is the sampling time for the j-th sampling point.

5. A terminal device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the power system power deficit estimation method as described in any one of claims 1 to 2.

6. A storage medium, characterized in that, The storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device where the storage medium is located to perform the power system power deficit estimation method as described in any one of claims 1 to 2.

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