A method for judging extension access of a transformer area side

Abstract

A kind of method for judging extension access of transformer area side industry, comprising the following steps: (1) obtaining transformer area three-phase power data;(2) the missing sampling time and power data missing in the obtained data are filled, and outlier is removed;(3) calculate the smooth fitting curve corresponding to the total three-phase power data of transformer area;(4) calculate the smooth fitting curve corresponding to the three-phase power data of the user who intends to apply for access transformer area;(5) according to the smooth fitting curve corresponding to the total three-phase power data of transformer area before and after access, when the load rate is greater than or equal to 80%, the length of time is used to judge whether to allow user access transformer area.The present application uses smooth curve fitting technology, judges whether to allow user access from the overall operation influence of user access to transformer area, is conducive to the transformer of light load state to access more power users.In comparison with traditional method, it can solve the problem of idle resources to some extent, and improve the operation state and utilization of transformer.

Description

Technical Field

[0001] This invention belongs to the field of power technology and relates to business expansion application, specifically a method for judging business expansion application access on the transformer substation side. Background Technology

[0002] With the rapid development of the market economy, the demand for electricity has increased accordingly. Under this trend, the volume of power industry expansion application services has seen an unprecedented surge. Faced with this massive volume, the power industry application system faces severe challenges. my country's power industry expansion application system is still not mature enough, unable to meet the required speed for applications, resulting in low efficiency and seriously hindering the development of the power industry. Therefore, in order to solve the current problem of idle power resources and further increase the volume of expansion application services, research on power industry expansion connection is particularly necessary and crucial.

[0003] The business expansion and installation application process is the primary channel for electricity customers to establish contact with the power supply company, a crucial link in building their relationship, and an important means for power companies to conduct effective marketing. When power companies conduct marketing, most of their marketing data comes from the data provided by the business expansion and installation department. This department analyzes and summarizes customer information, then organizes and uploads it, achieving information sharing among various departments within the power supply company through this information processing method. Therefore, the business expansion and installation application process is of great significance; it serves as a window between customers and the power supply company, impacting the quality of power system operation and management, as well as the service quality and image of the power company.

[0004] Existing methods for judging the impact of new business expansion applications often employ a "one-size-fits-all" approach. This involves overlaying the three-phase power data curves of the prospective user onto the corresponding three-phase power data curves of the transformer substation. If the peak load of any phase in the overlaid curve exceeds 80% of the rated load, the application is deemed ineligible. However, in practice, this method has limitations. Occasionally, the peak load may exceed 80%, which is within the substation's capacity. The current method, using isolated data sampling points to judge the overall impact of user access on substation operation, is overly stringent, leading to low economic efficiency. According to a data report from a local power grid company, the average available capacity ratio of a certain substation in 2019 was 40.69%, indicating a large available capacity margin, a high proportion of light no-load, low economic efficiency, and underutilization of the substation's transformer operating efficiency. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for judging business expansion and installation access on the transformer substation side based on third-order Bézier curve fitting, in order to solve the problem of the existing "one-size-fits-all" judgment method.

[0006] The technical solution of this invention is: a method for judging the application for business expansion and access on the transformer substation side, comprising the following steps:

[0007] 1) Obtain the three-phase power data of the transformer area, including the total three-phase power data of the transformer area and the three-phase power data of existing users in various industries in the transformer area. The power data is sampled once per hour and the power data time length is one calendar year.

[0008] 2) Data preprocessing: fill in the missing sampling time and power data in the acquired data, and use the local outlier factor algorithm to check whether there are outliers in the preprocessed data and remove the outliers.

[0009] 3) Based on the data processed in step 2), calculate the smooth fitting curve corresponding to the total three-phase power data of the transformer area;

[0010] 4) Calculate the smoothed fitting curve corresponding to the three-phase power data of the user in the proposed access area;

[0011] 5) Determine whether to allow the user applying for access to the transformer area: Superimpose the smoothed fitting curves corresponding to the three-phase power data of the user applying for access to the transformer area onto the smoothed fitting curves corresponding to the total three-phase power data of the corresponding transformer area to obtain the smoothed fitting curves corresponding to the total three-phase power data of the transformer area before and after access. Calculate the duration of the smoothed fitting curves corresponding to the total three-phase power data of the transformer area before and after access: If the duration of the smoothed fitting curves corresponding to the total three-phase power data of the transformer area before and after access does not change, the user applying for access to the transformer area is allowed to access; otherwise, if the duration of the smoothed fitting curves corresponding to the total three-phase power data of the transformer area before and after access changes, access is not allowed.

[0012] Furthermore, the smoothed fitting curve is a third-order Bézier curve. The upper envelope of the three-phase power data is calculated, and the third-order Bézier curve is fitted based on the upper envelope result to obtain the third-order Bézier curve corresponding to the three-phase power data.

[0013] The present invention has the following beneficial effects:

[0014] (1) This invention proposes a new method for judging whether to allow user access for business expansion applications. It uses the duration of 80% load in the front and back office areas as the judgment condition. The method determines whether to allow user access based on the overall operational impact on the transformer substation, rather than on whether the substation experiences a load exceeding 80%. As long as the load in the back office area does not exceed the original load of the substation, even if it exceeds 80% for some periods, it is acceptable. This invention can comprehensively assess the impact of user access on the substation, unlike existing technologies that prohibit any overload. This invention can fully utilize the operating efficiency of the transformer substation and effectively utilize the available capacity of the substation.

[0015] (2) The curve fitting-based method for judging the application for expansion of transformer substations in this invention is particularly suitable for transformer substations under light load conditions, and can connect more electricity users as appropriate. Compared with traditional methods, it can solve the problem of idle resources to a certain extent and improve the operating status and utilization rate of transformers on the substation side. Attached Figure Description

[0016] Figure 1 This is a flowchart of the method for determining the application and access of a business expansion application on the transformer substation side according to the present invention.

[0017] Figure 2 This is a schematic diagram of the data preprocessing process in the method of the present invention.

[0018] Figure 3 This is a schematic diagram of a third-order Bézier curve.

[0019] Figure 4 This is a schematic diagram of the third-order Bezier curve of phase A in the access area of ​​a residential industrial user in an embodiment of the present invention.

[0020] Figure 5 This embodiment of the invention illustrates the changes in the load rates of phases A, B, and C before and after a residential user applies for access to a transformer substation. Detailed Implementation

[0021] This invention provides a method for determining the application for business expansion and access on the transformer substation side, the implementation steps of which are as follows:

[0022] 1. Data Acquisition

[0023] Acquire three-phase power data for the distribution area, including total three-phase power data for the area and three-phase power data for users in various industries. The power data is sampled once per hour, and the data period is one calendar year.

[0024] 2. Data Preprocessing

[0025] Missing sampling times and power data in the acquired data were imputed, and the effectiveness of the data imputation was verified using the local outlier factor algorithm. Outliers were removed. The data preprocessing workflow is as follows: Figure 2 As shown.

[0026] The missing three-phase power data in the transformer area is mainly divided into two categories: missing sampling time and missing power data. Missing sampling time is manifested as a missing sampling time corresponding to a certain phase power data, while missing power data is manifested as a certain phase power data being 0 at a certain moment. For missing sampling time, the method adopted is to manually fill in the time so that the sampling time for each day is 00:00, 01:00, ..., 23:00, for a total of 24 sampling moments. For missing power data, if the power data of a certain phase is missing at only one sampling moment, the average power data of the sampling point before and after the missing position is used to fill it in; if the power data of a certain phase is missing at m consecutive sampling moments, the power data of the m sampling points before the missing position is used to fill it in.

[0027] Meanwhile, to verify the effectiveness of missing data imputation in power data, the Local Outlier Factor (LOF) algorithm was used to identify outliers in the preprocessed data. The LEF algorithm is a density-based outlier detection algorithm suitable for high-dimensional data. Its core idea is that the density at an outlier should be lower than the density of other points in its neighborhood.

[0028] The Local Outlier Factor algorithm defines the k-distance: for a data point p, the k-th distance from other points in its neighborhood to p, arranged in ascending order, is denoted as the k-th distance. It also defines reachability distance: if the actual distance from other points in the neighborhood to p is less than the k-distance, then the distance from p to p is considered to be the k-distance; otherwise, it is the actual distance, denoted as rdist. The local reachability density lrd(p) is the reciprocal of the average reachability distance ∑rdist from p in the neighborhood.

[0029]

[0030] The local outlier factor lof(p) can be obtained from the local reachability density, where lof(p) is the mean of the local reachability density of each point in the neighborhood. Divide by the local reachability density lrd(p) at point p,

[0031]

[0032] The closer the lof(p) ratio is to 1, the more similar the density of the neighborhood points of p. Generally speaking, when lof(p) is greater than 3, point p is considered an outlier and is removed.

[0033] 3. Calculate the third-order Bézier curve corresponding to the total three-phase power data of the transformer area.

[0034] The smoothing and fitting curves in this invention serve two purposes: data smoothing and data fitting. Because the collected data is collected hourly, curve fitting is used to obtain more fitting points for more accurate duration calculations. After data fitting, points can be obtained every half hour or 15 minutes. Data smoothing and fitting allow for a more accurate acquisition of the user load curve, thus better calculating the duration when the load reaches 80% in subsequent steps, resulting in more accurate calculations. This invention preferentially uses third-order Bézier curves.

[0035] The upper envelope of the total three-phase power data of the transformer area is calculated, and the third-order Bezier curve is fitted based on the upper envelope result to obtain the third-order Bezier curve corresponding to the total three-phase power data of the transformer area before connection.

[0036] Third-order Bézier curves, such as Figure 3 The four control points are P0(A0,B0), P1(A1,B1), P2(A2,B2), and P3(A3,B3). The mathematical expression for a third-order Bézier curve is:

[0037]

[0038] A third-order Bézier curve P(τ)=(x(τ),y(τ)) can be expressed in the form P(τ)=(x(τ),y(τ)), where x(τ) and y(τ) are respectively:

[0039] x(τ)=A0(1-τ) 3 +3A1(1-τ) 2 τ+3A2(1-τ)τ 2 +3A3τ 3 (4)

[0040] y(τ)=B0(1-τ) 3 +3B1(1-τ) 2 τ+3B2(1-τ)τ 2 +3B3τ 3 (5)

[0041] The curvature of the curve at any point is:

[0042]

[0043] Tangents at both ends:

[0044]

[0045]

[0046] Since Bézier curves are divided into multiple Bézier curve segments, adjacent Bézier curves are connected. Assume that two adjacent Bézier curves P(τ) and U(τ) are connected at point L, then...

[0047] P(L)=U(L),…,P (n) (L)=U (n) (L) (9)

[0048] The above formula is the existing technology for third-order Bézier curves and will not be described in detail here.

[0049] 4. Calculate the third-order Bézier curves corresponding to the three-phase power data of the users in the proposed access area.

[0050] If the user intends to access a transformer substation, and any of its subordinate users fall into the same category as the user in question, then the three-phase power data of these users within the same substation are extracted. The average three-phase power data at the corresponding time point is calculated, and an upper envelope calculation is performed on the average three-phase power data. Based on the upper envelope result, a third-order Bézier curve is fitted to obtain the third-order Bézier curve corresponding to the three-phase power data of the user in question. If the user intends to access a transformer substation, and none of its subordinate users fall into the same category as the user in question, then the three-phase power data of all users within a 5-kilometer radius of the transformer substation within the same substation are extracted. The average three-phase power data at the corresponding time point is calculated, and an upper envelope calculation is performed on the average three-phase power data. Based on the upper envelope result, a third-order Bézier curve is fitted to obtain the third-order Bézier curve corresponding to the three-phase power data of the user in question.

[0051] 5. Determine whether the user applying for access to the distribution area is allowed to access the distribution area.

[0052] The third-order Bézier curves corresponding to the three-phase power data of the user applying for access are superimposed onto the third-order Bézier curves corresponding to the total three-phase power data of the corresponding phase of the transformer area to obtain the third-order Bézier curves corresponding to the total three-phase power data of the back-end area. The duration of the third-order Bézier curves corresponding to the total three-phase power data of the back-end area before and after access is calculated as greater than or equal to 80% load rate. If the duration of the third-order Bézier curves corresponding to the three-phase power data of the back-end area does not change after access, access is allowed. Otherwise, if the duration of the third-order Bézier curves corresponding to the three-phase power data of any phase changes, access is not allowed.

[0053] Figure 4 As an example, the third-order Bézier curves of each phase A of the access area applied for by a residential industry user are shown.

[0054] Figure 5 Changes in the load rates of phases A, B, and C before and after a residential user applied for access to a transformer substation. Based on... Figure 5 It is known that the connection of residential users did not affect the duration of the load rate of 80% or higher, therefore, residential users are allowed to connect to the proposed transformer area.

[0055] This invention determines the load status of the user access front-end and back-end areas by calculating load duration changes, rather than using load changes at a single point in time as the basis for judgment. Bezier curves are an aid to data processing and are beneficial to data accuracy. Other alternative means with the same function can be used without departing from the design concept of this invention, and all of them are within the protection scope of this invention.

Claims

1. A method for judging the application for service expansion and access on the transformer substation side, characterized in that: Includes the following steps: 1) Obtain the three-phase power data of the transformer area, including the total three-phase power data of the transformer area and the three-phase power data of existing users in various industries in the transformer area. The power data is sampled once per hour and the power data time length is one calendar year. 2) Data preprocessing: fill in the missing sampling time and power data in the acquired data, and use the local outlier factor algorithm to check whether there are outliers in the preprocessed data and remove the outliers. 3) Based on the data processed in step 2), calculate the smooth fitting curve corresponding to the total three-phase power data of the transformer area; 4) Calculate the smoothed fitting curve corresponding to the three-phase power data of the user in the proposed access area; 5) Determine whether to allow the user applying for access to the transformer area: Superimpose the smoothed fitting curves corresponding to the three-phase power data of the user applying for access to the transformer area onto the smoothed fitting curves corresponding to the total three-phase power data of the corresponding transformer area to obtain the smoothed fitting curves corresponding to the total three-phase power data of the transformer area before and after access. Calculate the duration of the smoothed fitting curves corresponding to the total three-phase power data of the transformer area before and after access: If the duration of the smoothed fitting curves corresponding to the total three-phase power data of the transformer area before and after access does not change, the user applying for access to the transformer area is allowed to access; otherwise, if the duration of the smoothed fitting curves corresponding to the total three-phase power data of the transformer area before and after access changes, access is not allowed.

2. The method for judging the application for business expansion and access on the transformer substation side according to claim 1, characterized in that: The smoothed fitting curve is a third-order Bezier curve. The upper envelope of the three-phase power data is calculated, and the third-order Bezier curve is fitted based on the upper envelope result to obtain the third-order Bezier curve corresponding to the three-phase power data.

3. A method for determining the application for service expansion and access on the transformer substation side according to claim 1 or 2, characterized in that: In step 2), if the sampling time is missing, time padding is performed so that the sampling time of each day is the hour, for a total of 24 sampling times. If the power data is missing, if the power data of a certain phase is missing at only 1 sampling time, the average value of the power data of the sampling points before and after the missing position is used to fill the missing data. If the power data of a certain phase is missing at m consecutive sampling times, the power data of the m sampling points before the missing position is used to fill the missing data.

4. A method for determining the application for business expansion and access on the transformer substation side according to claim 1 or 2, characterized in that: The local outlier factor algorithm in step 2) specifically handles the following: Define distance k: for a data point p, within its neighborhood, the kth largest distance from other points to p, arranged in ascending order, is denoted as distance k; Define reachability distance: if the actual distance from other points in the neighborhood to p is less than distance k, then the distance from that point to p is considered to be distance k; otherwise, it is its actual distance, denoted as rdist; The local reachability density lrd(p) is the reciprocal of the average reachability distance ∑rdist within the neighborhood to point p. The local outlier factor lof(p) is calculated from the local reachability density, where lof(p) is the mean of the local reachability density of each point in the neighborhood. Divide by the local reachability density lrd(p) at point p: The closer the lof(p) ratio is to 1, the more similar the density of the neighborhood points of p. When lof(p) is greater than 3, p is considered an outlier and is removed.

5. A method for determining the application for service expansion and access on the transformer substation side according to claim 1 or 2, characterized in that: In step 4), if the user applying for access to the transformer substation has users of the same category as the user applying for access to the transformer substation, then the three-phase power data of the users of the same category under the transformer substation are extracted, and the average value of the three-phase power data at the corresponding time point is calculated. The upper envelope of the average value of the three-phase power data is calculated, and a third-order Bézier curve is fitted based on the upper envelope result, which is used as the third-order Bézier curve corresponding to the three-phase power data of the user applying for access to the transformer substation. If the user applying for access to the transformer substation does not have users of the same category as the user applying for access to the transformer substation, then the three-phase power data of all users of the same category under the transformer substation within a 5-kilometer radius of the transformer substation are extracted, and the average value of the three-phase power data at the corresponding time point is calculated. The upper envelope of the average value of the three-phase power data is calculated, and a third-order Bézier curve is fitted based on the upper envelope result, which is used as the third-order Bézier curve corresponding to the three-phase power data of the user applying for access to the transformer substation.

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