A power distribution network parameter estimation method and system based on mixed measurement values

Abstract

The application provides a power distribution network parameter estimation method and system based on mixed measurement values, comprising: obtaining voltage synchronous vectors and current synchronous vectors of a bus connected with a power supply and voltage amplitudes of other buses; obtaining power distribution network parameter estimation results according to the obtained voltage synchronous vectors, current synchronous vectors and voltage amplitudes and a preset mixed measurement value estimation model; the obtaining process of the mixed measurement value estimation model is: obtaining physical law equations of measurement parameters and estimation parameters in the power distribution network according to Kirchhoff's current law; separating real parts and imaginary parts of the physical law equations; establishing a model containing a phasor information matrix and an amplitude information matrix according to the separated equations; the application provides a new mixed measurement value model, which can achieve the purpose of accurately estimating parameters in the power distribution network, and on this basis, the installation of synchronous phasor measurement devices in lines can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of distribution network parameter estimation, and in particular relates to a distribution network parameter estimation method and system based on hybrid measurement values. Background Art

[0002] Distribution network parameters are typically provided by established databases. However, due to the effects of inclement weather, human factors, and the aging of the network, these parameters often differ significantly from known parameters. Since subsequent applications such as power flow calculations, line protection, and fault location require precise line parameters, these discrepancies can introduce significant errors.

[0003] The inventors of the present invention have found that the existing distribution network parameter estimation method has the following problems:

[0004] The impact of different bus types on measurement data and parameter estimation results is not considered, resulting in the inability of existing parameter estimation models to accurately estimate parameters in the distribution network. At the same time, when using existing distribution network parameter estimation, a large number of synchronized phasor measurement devices need to be installed in the line, resulting in high costs. The superposition of errors from multiple synchronized phasor measurement devices affects the accuracy of the estimation results. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a distribution network parameter estimation method and system based on hybrid measurement values. The present invention proposes a new hybrid measurement value model, which can achieve the purpose of accurately estimating parameters in the distribution network. On this basis, the installation of synchronized phasor measurement devices in the line can be reduced.

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

[0007] In a first aspect, the present invention provides a method for estimating distribution network parameters based on hybrid measurements, comprising:

[0008] Obtain the voltage synchronous vector and current synchronous vector of the bus connected to the power source, as well as the voltage amplitude of other types of buses;

[0009] The distribution network parameter estimation results are obtained based on the obtained voltage synchronous vector, current synchronous vector and voltage amplitude, as well as the preset hybrid measurement value estimation model;

[0010] The acquisition process of the hybrid measurement value estimation model is as follows: Kirchhoff's current law is used to obtain the physical law equations of the measurement parameters and estimated parameters in the distribution network; the real part and the imaginary part of the physical law equation are separated; and based on the separated equations, a model including the phasor information matrix and the amplitude information matrix is ​​established.

[0011] Furthermore, the physical law equation is: the product of the admittance matrix of the entire distribution network parameters and the bus voltage vector, and the equation of the equation of all bus current injection vectors.

[0012] Furthermore, the establishment of the phasor information matrix and the amplitude information matrix depends on indicators of other types of buses.

[0013] Furthermore, the phasor information matrix M Pha and the amplitude information matrix M Mag The establishment includes:

[0014] Build M Pha M Pha =[re(M Pha ) im(M Pha )], where M Pha Contains the real and imaginary parts of the voltage phasors on other types of buses;

[0015] Define the index g as the busbar number, and define the index k as M Pha and M Mag The row number of

[0016] Generate M Pha and M Mag for:

[0017]

[0018]

[0019] in,[·] j,k represents the jth row and kth column of its matrix; Represents the vector containing all bus voltages.

[0020] Furthermore, a new admittance matrix is ​​defined New bus current injection vector Among them, Y is the admittance matrix after decomposing the physical law equation, and I is the bus current injection vector after decomposing the physical law equation.

[0021] Furthermore, snapshots are used to uniquely identify the model solution, where each set of snapshots corresponds to a set of voltage and current measurements.

[0022] Furthermore, when solving the mixed measurement value estimation model, the Newton iteration method is used to solve it, and the Jacobian matrix in the iteration is solved by a numerical method.

[0023] In a second aspect, the present invention further provides a distribution network parameter estimation system based on hybrid measurement values, comprising a data acquisition module and a parameter estimation module;

[0024] The data acquisition module is configured to: acquire bus-related data, including voltage synchrophasors and current synchrophasors of the bus connected to the power source, and voltage amplitudes of other types of buses;

[0025] The parameter estimation module is configured to obtain distribution network parameter estimation results based on the obtained voltage synchronous vector, current synchronous vector and voltage amplitude, and a preset hybrid measurement value estimation model;

[0026] The acquisition process of the hybrid measurement value estimation model is as follows: Kirchhoff's current law is used to obtain the physical law equations of the measurement parameters and estimated parameters in the distribution network; the real part and the imaginary part of the physical law equation are separated; based on the separated equations, a model containing the phasor information matrix and the amplitude information matrix is ​​established; and a snapshot is used to uniquely identify the model solution.

[0027] In a third aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the distribution network parameter estimation method based on hybrid measurements described in the first aspect.

[0028] In a fourth aspect, the present invention also provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the method for estimating distribution network parameters based on hybrid measurements described in the first aspect are implemented.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention proposes a new hybrid measurement value model that can achieve the purpose of accurately estimating parameters in the distribution network. At the same time, during the estimation process, it is not necessary to perform excessive vector measurements on the second-class busbars. Instead, the voltage amplitude of the second-class busbars is obtained, which can reduce the installation of synchronized phasor measurement devices in the line. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings constituting a part of the description of this embodiment are used to provide a further understanding of this embodiment. The exemplary embodiments and descriptions of this embodiment are used to explain this embodiment and do not constitute improper limitations on this embodiment.

[0032] Figure 1 This is a flow chart of Example 1 of the present invention;

[0033] Figure 2 The test system of embodiment 1 of the present invention;

[0034] Figure 3 is the absolute error of the real part of the admittance matrix of Example 1 of the present invention;

[0035] Figure 4 is the absolute error of the imaginary part of the admittance matrix in embodiment 1 of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0038] Example 1:

[0039] This embodiment provides a method for estimating distribution network parameters based on hybrid measurements, including:

[0040] Obtain bus-related data, including the voltage and current synchrophasors of the bus connected to the power source, and the voltage amplitudes of other types of buses;

[0041] The distribution network parameter estimation results are obtained based on the obtained voltage synchronous vector, current synchronous vector and voltage amplitude, as well as the preset hybrid measurement value estimation model;

[0042] The acquisition process of the hybrid measurement value estimation model is as follows: Kirchhoff's current law is used to obtain the physical law equations of the measurement parameters and estimated parameters in the distribution network; the real part and the imaginary part of the physical law equation are separated; based on the separated equations, a model containing the phasor information matrix and the amplitude information matrix is ​​established; and a snapshot is used to uniquely identify the model solution.

[0043] Specifically, such as Figure 1 The method can be divided into constructing a mixed measurement value estimation model and solving the mixed measurement value estimation model.

[0044] In this embodiment, constructing the hybrid measurement value estimation model includes:

[0045] For a distribution network system with n buses, based on Kirchhoff's Current Law (KCL), the physical laws of the entire network can be described by the following equation:

[0046]

[0047] in, is the admittance matrix containing the parameters of the entire system, is a vector containing all bus voltages, is a vector containing all bus current injections.

[0048] Since the current injection vector The measured values ​​in equation (1) can generally be divided into the following two categories:

[0049] Category 1 (busbar connected to power supply): the required measurement values ​​are the phasor values ​​of voltage and power;

[0050] The second type (other types of buses): the measured value is the phasor value of the voltage.

[0051] From equation (1) and the division of the two types of measurements, it can be seen that if equation (1) is used to To estimate the voltage phasor values ​​of the second-class busbars, synchronized phasor measurement devices must be installed on them. However, in practical distribution networks, it is not possible to install synchronized phasor measurement devices on all buses. To reduce the installation of synchronized phasor measurement devices and avoid measuring the phase angle of the voltage on the second-class busbars, this embodiment proposes the following new definitions to facilitate the establishment of a hybrid measurement model and ultimately achieve accurate parameter estimation.

[0052] Category 1 (busbar connected to power supply): the required measurement values ​​are the phasor values ​​of voltage and power;

[0053] The second type (other types of buses): the value to be measured is the voltage amplitude.

[0054] As can be seen from the above new definition, the real and imaginary parts of the voltage phasor of the second-class bus are both unknown, and the only information that can be obtained is the voltage amplitude on the second-class bus. In this regard, this embodiment proposes an estimation model for mixed measurement values ​​and introduces how to use this model for parameter estimation.

[0055] First, separate the real and imaginary parts of equation (1) and establish the equivalent equation (2) as follows:

[0056] Y·V=I (2)

[0057] in, re(·) represents the real part of its matrix, and im(·) represents the imaginary part of its matrix.

[0058] On the basis of equation (2), in order to avoid measuring the voltage phase angle on the second type of bus, in this embodiment, equation (2) is re-modeled; for the convenience of modeling, the “phasor information matrix” is defined as: Define the "amplitude information matrix" as: p represents the number of the second type of busbars in the system, such as Figure 2 As shown, in this embodiment, a 14-bus system is adopted, and p=9.

[0059] It is worth noting that and Depends on the indicators of the second type of busbar; for example, Figure 2 The indicator definitions of the 14-bus system are shown in Table 1:

[0060] Table 1.14-bus system indicators of the second type of bus

[0061] The second type busbar label 4 5 7 9 10 11 12 13 14 <![CDATA[M Pha , M Mag Line number of ]]> 1 2 3 4 5 6 7 8 9

[0062] As shown in Table 1, after the labels are established, M Pha and M Mag It can be established by following the steps below:

[0063] Step 1: Build M Pha M Pha =[re(M Pha )im(M Pha )], where M Pha Contains the real and imaginary parts of the voltage phasor on the second type bus;

[0064] Step 2: Define the index g as the busbar number and define the index k as M Pha and M Mag The row number of

[0065] Step 3: Generate M using formula (3) Pha and M Mag

[0066]

[0067] in,[·] j,k represents the jth row and kth column of its matrix.

[0068] Then, when M Pha and M Mag After the construction is completed, the final model determination process is:

[0069] definition in and

[0070] According to the new definition, equation (2) can be written as equation (4),

[0071] Y Pha V = I Mag (4)

[0072] Since the number of unknowns in equation (4) is much greater than the number of measured values, in order to make equation (4) have a unique solution, in this embodiment, the use of snapshots is introduced; wherein each set of snapshots corresponds to a set of voltage and current measurement values; by collecting multiple sets of snapshots in a short period of time, equation (5) can be obtained,

[0073]

[0074] Where m is the number of snapshots, (·) (h) Indicates the h-th snapshot.

[0075] To simplify the notation, the equivalent equation of equation (5) is,

[0076] Y sp ·V sp =I sp (6)

[0077] in, is a block diagonal matrix,

[0078] In this embodiment, solving the mixed measurement value estimation model includes:

[0079] like Figure 2 As shown, in this embodiment, the parameter estimation of the 14-bus system is taken as an example to solve equation (6). First, rearranging equation (6) can obtain equation (7),

[0080] y=U(x) (7)

[0081] Where y = I sp is the measurement vector, x is the state vector to be estimated, which includes the admittance matrix Y bus and the real and imaginary parts of the voltage on the second type bus.

[0082] For a 14-bus system, assuming a snapshot time of 4, there are 140 unknowns that need to be estimated. The relationship between all unknowns and x is shown in Table 2:

[0083] Table 2. Relationship between unknowns and x vectors

[0084]

[0085] Then, in order to systematically solve the vector x in equation (7), the following optimization problem is established:

[0086]

[0087] Equation (8) can be solved by Newton's iteration method, and the iterative steps are as follows:

[0088] x ψ+1 =x ψ -(H T H) -1 H T (x ψ )·(U(x)-y) (9)

[0089] where, is the Jacobian matrix of U(x).

[0090] In this embodiment, the Jacobian matrix is solved using numerical method, and the specific formula is:

[0091] H = [G(x ψ + Δx) - G(x ψ - Δx)] / (2Δx) (10)

[0092] where Δx is a small perturbation.

[0093] Finally, in this embodiment, a 9-bus test system is built in the simulation software PSCAD, and the sample is as shown in Figure 2 The tested system has a total of 5 buses with generators, 11 loads, 20 branches and 3 transformers; the available measurement values are as shown in Figure 2 In order to improve the redundancy of the problem, in this embodiment, five groups of snapshots are used.

[0094] In order to verify the performance of the application, the following two metrics are used for judgment:

[0095] Metric 1: by comparing the estimated value and the true value;

[0096] Metric 2: define the absolute error of the real part and the imaginary part as

[0097]

[0098]

[0099] where ReAM Error(%) = 0 and Im AM Error(%) = 0 represent a perfect estimate;

[0100] The results of the true value and the estimated value of the parameter estimation are shown in Table 3 and Table 4, and the absolute errors of the real part and the imaginary part of the admittance matrix are shown in Figure 3 and Figure 4 .

[0101] Table 3 Comparison of true value and estimated value of result 1

[0102]

[0103] Table 4 Comparison of true value and estimated value of result 2

[0104]

[0105]

[0106] It can be seen that the parameter estimation method in this embodiment can obtain accurate system parameters.

[0107] Example 2:

[0108] This embodiment provides a distribution network parameter estimation system based on hybrid measurement values, including a data acquisition module and a parameter estimation module;

[0109] The data acquisition module is configured to: acquire bus-related data, including voltage synchrophasors and current synchrophasors of the bus connected to the power source, and voltage amplitudes of other types of buses;

[0110] The parameter estimation module is configured to obtain distribution network parameter estimation results based on the obtained voltage synchronous vector, current synchronous vector and voltage amplitude, and a preset hybrid measurement value estimation model;

[0111] The acquisition process of the hybrid measurement value estimation model is as follows: Kirchhoff's current law is used to obtain the physical law equations of the measurement parameters and estimated parameters in the distribution network; the real part and the imaginary part of the physical law equation are separated; based on the separated equations, a model containing the phasor information matrix and the amplitude information matrix is ​​established; and a snapshot is used to uniquely identify the model solution.

[0112] Example 3:

[0113] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the steps of the method for estimating distribution network parameters based on hybrid measurements described in Embodiment 1 are implemented.

[0114] Example 4:

[0115] This embodiment provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the method for estimating distribution network parameters based on hybrid measurements described in Embodiment 1 are implemented.

[0116] The above description is merely a preferred embodiment of this embodiment and is not intended to limit this embodiment. Those skilled in the art will readily appreciate that this embodiment may be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this embodiment shall be within the scope of protection of this embodiment.

Claims

1. A method for estimating distribution network parameters based on hybrid measurements, characterized in that: include: Obtain the voltage synchronous vector and current synchronous vector of the bus connected to the power source, as well as the voltage amplitude of other types of buses; The distribution network parameter estimation results are obtained based on the obtained voltage synchronous vector, current synchronous vector and voltage amplitude, as well as the preset hybrid measurement value estimation model; The acquisition process of the hybrid measurement value estimation model is as follows: for a distribution network system with n buses, the physical law equations of the measurement parameters and estimated parameters in the distribution network are obtained based on Kirchhoff's current law, specifically: ;in, is the admittance matrix containing the parameters of the entire system, is a vector containing all bus voltages, is a vector containing all bus current injections; Separate the real and imaginary parts of the physical law equation and establish an equivalent equation, specifically: ,in, , , , represents the real part of its matrix, represents the imaginary part of its matrix; The equivalent equation is remodeled and the phasor information matrix is ​​defined as: , the amplitude information matrix is: , where p represents the number of other types of buses in the system; The phasor information matrix and the amplitude information matrix The establishment includes: Build for ,in, Contains the real and imaginary parts of the voltage phasors on other types of buses; Defining Metrics g Define the index for the busbar number k for and The row number of generate and for: in, represents the vector containing all bus voltages; After the phasor information matrix and amplitude information matrix are established, define the new admittance matrix , the new bus current injection vector ,in, is the admittance matrix after decomposing the physical law equation, It is the bus current injection vector after decomposing the physical law equation.

2. A method for estimating distribution network parameters based on hybrid measurements according to claim 1, characterized in that: The new admittance matrix and The new bus current injection vector relationship is: ,in, ; Using snapshot implementation The solution is unique; the hybrid measurement value estimation model is solved using the new admittance matrix and the new bus current injection vector.

3. A method for estimating distribution network parameters based on hybrid measurements according to claim 2, characterized in that: The snapshot is used to achieve The solution is unique, specifically: each set of snapshots corresponds to a set of voltage and current measurements, obtained by collecting multiple sets of snapshots in a short period of time: ,in, m is the number of snapshots, , , , Indicates the h Second snapshot; The equivalent equation of the above equation is: ;in, is a block diagonal matrix, , .

4. A method for estimating distribution network parameters based on hybrid measurements according to claim 3, characterized in that: The hybrid measurement value estimation model is solved by using the new admittance matrix and the new bus current injection vector, specifically: According to the equation After sorting, we get ,in, is the measurement vector, x is the state vector to be estimated, which includes the admittance matrix and the real and imaginary parts of the voltage on the second type busbar; solve the equation Vectors in x , set up the optimization problem: ; The optimization problem is solved by Newton iteration method, and its iterative steps are: ,in, for Jacobian matrix; use numerical method to solve the Jacobian matrix, the specific formula is: ,in For a tiny disturbance.

5. A distribution network parameter estimation system based on hybrid measurement values, characterized in that: Including data acquisition module and parameter estimation module; The data acquisition module is configured to: acquire bus-related data, including voltage synchrophasors and current synchrophasors of the bus connected to the power source, and voltage amplitudes of other types of buses; The parameter estimation module is configured to obtain distribution network parameter estimation results based on the obtained voltage synchronous vector, current synchronous vector and voltage amplitude, and a preset hybrid measurement value estimation model; The acquisition process of the hybrid measurement value estimation model is as follows: for a distribution network system with n buses, the physical law equations of the measurement parameters and estimated parameters in the distribution network are obtained based on Kirchhoff's current law, specifically: ;in, is the admittance matrix containing the parameters of the entire system, is a vector containing all bus voltages, is a vector containing all bus current injections; Separate the real and imaginary parts of the physical law equation and establish an equivalent equation, specifically: ,in, , , , represents the real part of its matrix, represents the imaginary part of its matrix; The equivalent equation is remodeled and the phasor information matrix is ​​defined as: , the phasor information matrix is: , where p represents the number of other types of buses in the system; The phasor information matrix and the amplitude information matrix The establishment includes: Build for ,in, Contains the real and imaginary parts of the voltage phasors on other types of buses; Defining Metrics g Define the index for the busbar number k for and The row number of generate and for: in, represents the vector containing all bus voltages; After the phasor information matrix and amplitude information matrix are established, define the new admittance matrix , the new bus current injection vector ,in, is the admittance matrix after decomposing the physical law equation, It is the bus current injection vector after decomposing the physical law equation.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method for estimating distribution network parameters based on hybrid measurements as described in any one of claims 1 to 4 are implemented.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the distribution network parameter estimation method based on hybrid measurements are implemented as described in any one of claims 1 to 4.

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