Real-time line loss calculation method based on high-voltage transmission network equivalent resistance and application

Abstract

The invention discloses a real-time line loss calculation method based on equivalent resistance of a high-voltage transmission network. The method comprises the following steps: firstly, establishing a group of equivalent resistance calculation models based on time sequence voltage and current data; and secondly, solving the model by adopting a least square method to obtain the equivalent resistance of the high-voltage power transmission network. And then, accurate identification of impedance parameters is realized by adopting a clustering method, and the line loss of a power transmission transformer region changes along with the power consumption condition of each node in real time, which is beneficial for a power supply company to screen the abnormal condition of the line loss. The invention provides a real-time line loss calculation method based on equivalent resistance of a high-voltage power transmission network, and aims to solve the problems that construction planning of the high-voltage power transmission network is imperfect, lines for balancing load distribution in operation are cut, recorded station and household topological relation information does not conform to reality, and theoretical line loss calculation of the power transmission network is difficult.

Description

Technical Field

[0001] The present invention relates to the field of energy, electricity and smart power transmission, and in particular to a real-time line loss calculation method based on equivalent resistance of a high-voltage transmission network and its application. Background Art

[0002] Line loss rate is an important economic indicator of power supply enterprises, and also an important indicator of the comprehensive management level of power supply enterprises. The line loss management level of power supply enterprises directly reflects the economic operation level and marketing management level of power grids. Reducing line loss is the eternal theme of power supply enterprises. However, due to various factors and complex on-site conditions, it is always difficult to reduce losses, which is also the difficulty of line loss management.

[0003] The voltage loss method assumes that the shape and power factor of each load curve are the same, and the line type needs to be known, so there are some errors. It is difficult to calculate the line loss of the high-voltage transmission network in detail and accurately. The loss rate method based on measured line loss requires that the selected typical station has no electricity theft and various tables are normal. The division of typical stations is difficult and the calculation accuracy is not high. The traditional equivalent resistance method requires the topology and component parameters of the high-voltage transmission network. Although the calculation accuracy is high, it is heavily dependent on the accuracy of the grid parameters and is difficult to calculate.

[0004] With the rapid development of artificial intelligence related methods, more and more researchers are applying neural networks, clustering and other methods to the calculation of transformer regional line losses. Summary of the invention

[0005] In view of this, in order to realize the dynamic calculation of the line loss of the high-voltage transmission network and solve the problem of the difficulty in calculating the theoretical line loss of the high-voltage transmission network, the present invention establishes a set of equivalent resistance calculation models based on time series voltage and current data, and adopts the least squares method to solve the problem, and obtains the equivalent resistance of the high-voltage transmission network. Finally, the clustering algorithm is used to improve the accuracy of the resistance parameters, and a real-time line loss calculation method based on the equivalent resistance of the high-voltage transmission network is designed. The technical scheme is as follows:

[0006] A real-time line loss calculation method based on equivalent resistance of a high-voltage transmission network, characterized by comprising:

[0007] Step 1: Establish a set of equivalent resistance calculation models based on time series voltage and current data;

[0008] Step 2: Use the least square method to solve the equivalent resistance calculation model to obtain the equivalent resistance of the high-voltage transmission network;

[0009] Step 3: Improve the accuracy of resistance parameters through clustering algorithm and design a real-time line loss calculation method based on the equivalent resistance of high-voltage transmission network.

[0010] Beneficial Effects

[0011] The present invention can obtain dynamic line loss that changes with time, and realize fine observation and evaluation of line loss in the transformer area; the basic data of the method has a high degree of fault tolerance, is suitable for actual engineering calculations, can provide accurate theoretical line loss reference values, meet the requirements of line loss analysis in the transformer field, and provide an effective basis for formulating loss reduction measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the high voltage transmission network-node equivalent circuit diagram;

[0013] Figure 2 It uses the DBSCAN algorithm to find the core object flow chart;

[0014] Figure 3 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0015] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0016] A real-time line loss calculation method based on equivalent resistance of a high-voltage transmission network comprises the following steps:

[0017] Step 1: Establish a set of equivalent resistance calculation models based on time series voltage and current data.

[0018] Due to the complex wiring between the high-voltage transmission network and each node, it is difficult to accurately measure the topology structure. Therefore, the structure between the high-voltage transmission network and each final node is equivalent to Figure 1 Assume that n nodes are connected under a certain platform, where node 0 represents the high voltage side of the transformer, and nodes 1, 2, 3, L, n represent the nodes connected under the transformer. For the convenience of formulation, the equivalent resistance is expressed in the form of resistance, G1, G2, G3, L, G n Represents the equivalent resistance of the circuit between the transmission transformer area and each node.

[0019] Figure 1 The voltage and current values ​​of each node in the data can be collected through the power consumption information collection system of the high-voltage transmission network. The collection frequency can generally reach one data point every 15 minutes. If research needs it, data can be recalled at any time. Assuming that the amount of data that can be collected in a day is t, and the collection time interval is uniform, the voltage value of each node i at time point t is (like It is represented by the voltage value of the first node at time point 1), and the current value of each node i is (like is represented by the current value of the first node at time point 1). At each moment, according to Kirchhoff's current law, the following equation can be listed:

[0020]

[0021] The system of equations can be written in the form of a matrix equation as follows:

[0022]

[0023] The equation can be simplified to UgG = I, where U and I are known quantities and G is the displacement quantity;

[0024] Step 2: Use the least squares method to solve the equivalent resistance calculation model and obtain the equivalent resistance of the high-voltage transmission network:

[0025] The equivalent resistance problem of solving the matrix equation can be transformed into solving the optimization problem:

[0026]

[0027] Since the values ​​of U and I in the matrix equation are obtained by the acquisition system, there will inevitably be some noise and errors, so the total least squares method is applicable to solving the matrix equation. Let U and I represent the error-free data that cannot be measured, and the actual measured data are:

[0028] U=U+E U ,I=I+E I

[0029] Among them, E U and E I Represent the measurement errors of voltage and current data respectively.

[0030] Correction matrices ΔU and ΔI are introduced to interfere with the original data matrices U and I, thereby jointly compensating for the errors or noises in matrices U and I:

[0031] U+ΔU=U+E U +ΔU→U

[0032] I+ΔI=I+E I +ΔI→I

[0033] By correcting the matrix, the influence of measurement error or noise on the matrix equation solution can be suppressed, thereby realizing the conversion from the matrix equation solution with error to the accurate equation solution, as shown in the following equation:

[0034]

[0035] In order to make the correction matrix as small as possible, the total least squares problem can be described as a constrained optimization problem as follows:

[0036]

[0037] st(U+ΔU)gG=I+ΔI

[0038] Since t is the number of measurement time points, t>n can be achieved by adjusting the acquisition frequency. That is, the above matrix equations are all overdetermined equations and are solved using the singular value decomposition (SVD) method.

[0039] The specific steps are as follows:

[0040] Input: U∈R t×n ,I∈R t ,α>0;

[0041] Output: ΔU∈R t×n ,ΔI∈R t ,G∈R t ;

[0042] Step 1: Calculate SVD[U,αI]=P∑Q H ,in,

[0043] Step 2: If σ n (U)>σ n+1 (where σ n (U) is the nth singular value of the matrix U), then the solution to the total least squares problem is given by:

[0044]

[0045]

[0046] Among them, p n+1 and q n+1 is the n+1 column of P and Q, Q ij is the (i,j) element of P.

[0047] Step 3: Improve the accuracy of resistance parameters through density-based clustering algorithm, and design a real-time line loss calculation method based on the equivalent resistance of high-voltage transmission network.

[0048] Since the voltage and current data collected at the transformer and each node side are changing every moment of every day, the calculated equivalent parameters are also changing. In order to improve the accuracy of the parameters, the present invention uses a large amount of historical data of the same date to calculate the equivalent resistance, and the date types include weekdays, Saturdays, Sundays, holidays, etc.

[0049] Firstly, the calculated equivalent resistance value is simplified into two dimensions. Then, the density-based spatial clustering of applications with noise (DBSCAN) is introduced to cluster the resistance parameter results. The parameter group corresponding to the core object in the set with the largest number of samples is selected as the equivalent resistance of the transmission transformer area.

[0050] The application process of DBSCAN algorithm is as follows Figure 2 shown.

[0051] The equivalent resistance between the transmission transformer area and each node is calculated by the DBSCAN algorithm. The equivalent resistance is R = 1 / G. By using the time series current values ​​measured at each node side, the line loss value of the transmission transformer area that changes with time can be calculated.

[0052] Assuming that the current values ​​at each node measured at time t are the average values ​​of the current period, the line loss at time t is (l j , l t represents line loss), and the daily line loss in the transmission transformer area is (Loss means daily line loss.) The line loss value is calculated based on the measured data and can be verified by statistical line loss. It will be more accurate as a line loss indicator in on-site evaluation.

[0053] This method can realize the dynamic calculation of line loss of high-voltage transmission network and identify the line loss of transmission transformer area in real time with the power consumption of each node. Therefore, we obtain a real-time line loss calculation method based on the equivalent resistance of high-voltage transmission network to solve the problem of difficulty in calculating theoretical line loss of transmission network.

[0054] In summary, in order to realize the dynamic calculation of the line loss of the high-voltage transmission network and solve the problem of the difficulty in calculating the theoretical line loss of the high-voltage transmission network, the present invention uses the time series voltage and current data collected from the distribution transformer area and the user side to establish a transmission network equivalent resistance calculation model. Considering the noise and error caused by the acquisition equipment and transmission, the total least squares method is used to solve the equation. A large number of data from the same day are used to calculate the equivalent resistance parameters of the transmission network, and a density-based clustering method is used to more accurately select the parameters of the core object, and a real-time line loss calculation method based on the equivalent resistance of the high-voltage transmission network is designed.

[0055] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A real-time line loss calculation method based on the equivalent resistance of a high-voltage transmission network, characterized in that: include: Step 1: Establish a set of equivalent resistance calculation models based on time series voltage and current data; Step 2: Use the least square method to solve the equivalent resistance calculation model to obtain the equivalent resistance of the high-voltage transmission network; Step 3: Improve the accuracy of resistance parameters through clustering algorithm and design a real-time line loss calculation method based on the equivalent resistance of high-voltage transmission network.

2. The real-time line loss calculation method based on the equivalent resistance of the high-voltage transmission network according to claim 1 is characterized in that: The step 1 includes the following contents: Assume that n nodes are connected under a certain platform, wherein each node 0 represents the high voltage side of the transformer, each node 1, 2, 3, L, n represents each node connected under the transformer, and n represents a node; G1, G2, G3, L, G n represents the equivalent resistance of the circuit between the transmission transformer area and each node; the voltage and current values ​​of each node are collected by the power consumption information collection system of the high-voltage transmission network; assuming that the amount of data that can be collected in one day is t, and the collection time interval is uniform, then the voltage value of each node i at time point t is The current value of each node i is At each moment, according to Kirchhoff's current law, the following equation is listed: The system of equations can be written in the form of a matrix equation as follows: The equation simplifies to UgG=I, where U and I are known quantities and G is the displacement quantity.

3. The real-time line loss calculation method based on the equivalent resistance of the high-voltage transmission network according to claim 2 is characterized in that: The step 2 includes the following contents: The equivalent resistance problem of solving the matrix equation is transformed into solving the optimization problem: Assume that U and I represent the error-free data that cannot be measured, and the actual measured data are: U=U+E U ,I=I+E I Among them, E U and E I Represent the measurement errors of voltage and current data respectively; Correction matrices ΔU and ΔI are introduced to interfere with the original data matrices U and I, thereby jointly compensating for the errors or noises in matrices U and I: U+ΔU=U+E U +ΔU→U I+ΔI=I+E I +ΔI→I By correcting the matrix, the influence of measurement error or noise on the matrix equation solution is suppressed, thereby realizing the conversion from the matrix equation solution with error to the accurate equation solution, as shown in the following equation: In order to make the correction matrix as small as possible, the total least squares problem is described as a constrained optimization problem as follows: st(U+ΔU)gG=I+ΔI Since t is the number of measurement time points, t>n is achieved by adjusting the acquisition frequency, that is, the above matrix equations are all overdetermined equations and are solved using the singular value decomposition (SVD) method.

4. The real-time line loss calculation method based on the equivalent resistance of the high-voltage transmission network according to claim 3 is characterized in that: The singular value decomposition method solution step includes the following contents: Input: U∈R t×n ,I∈R t ,α>0; Output: ΔU∈R t×n ,ΔI∈R t ,G∈R t ; Step 1: Calculate SVD[U,αI]=P∑Q H ,in, Wherein, SVD[U,αI] is a U×αI matrix, P is an orthogonal matrix of U×U, ∑ is a non-negative diagonal matrix of U×αI, Q is an orthogonal matrix of αI×αI, P is a left singular quantity, ∑ is a singular value, Q is a right singular quantity, diag represents a diagonal matrix, and α is a parameter; Step 2: If σ n (U)>σ n+1 , where σ n (U) is the nth singular value of the matrix U, then the solution to the total least squares problem is given by: Among them, p n+1 and q n+1 is the n+1 column of P and Q, Q ij is the (i,j) element of P.

5. The real-time line loss calculation method based on the equivalent resistance of the high-voltage transmission network according to claim 1 is characterized in that: The step 3 includes the following contents: The calculated equivalent resistance value is simplified into two dimensions, and then the density-based spatial clustering DBSCAN with noise is introduced to cluster the resistance parameter results, and the parameter group corresponding to the core object in the set with the largest number of samples is selected as the equivalent resistance of the transmission transformer area.

6. The real-time line loss calculation method based on the equivalent resistance of the high-voltage transmission network according to claim 5 is characterized in that: The DBSCAN algorithm for spatial clustering with noise includes the following contents: The equivalent resistance between the transmission transformer area and each node is calculated by the DBSCAN algorithm; the equivalent resistance is R = 1 / G, and the line loss value of the transmission transformer area that changes with time is calculated by using the time series current values ​​measured at each node side; Assuming that the current values ​​at each node measured at time t are the average values ​​of the current period, the line loss at time t is l j , l t Represents line loss. The daily line loss in the transmission transformer area is Loss means daily loss; The line loss value is calculated based on the measured data and verified using statistical line loss.

7. A non-volatile storage medium, characterized in that: The non-volatile storage medium includes a stored program, wherein when the program is executed, the device where the non-volatile storage medium is located is controlled to execute the method according to any one of claims 1 to 6.

8. An electronic device, characterized in that: It comprises a processor and a memory; the memory stores computer-readable instructions, and the processor is used to execute the computer-readable instructions, wherein the computer-readable instructions execute the method described in any one of claims 1 to 6 when executed.

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