CN109581130B - Voltage curve similarity calculation method considering voltage adjustment measure influence - Google Patents

Abstract

The present invention provides a method for calculating the similarity of voltage curves considering the influence of voltage adjustment measures, which includes the following steps: A. Obtaining relevant data of distribution transformers. Name, distribution transformer address code, distribution transformer three-phase voltage; B. Preprocess the distribution transformer outlet voltage data obtained in step A; C. Identify the voltage mutation point according to the distribution transformer outlet voltage data preprocessed in step B, and analyze the voltage The curve is segmented; D. Calculate the similarity of the segmented curves according to the segmentation result of the voltage curve in step C; E. According to the similarity result of the segmented curve calculated in step D, comprehensively judge the similarity of the voltage curves of the two stations . Through the method proposed in the present invention, the similarity of the voltage curves when there are voltage adjustment measures can be calculated correctly.

Description

A voltage curve similarity calculation method considering the influence of voltage adjustment measures

technical field

The invention relates to the technical field of distribution transformer operation, in particular to a voltage curve similarity calculation method considering the influence of voltage adjustment measures.

Background technique

When the distribution network is running, in order to reduce the active network loss, balance the load, and improve the reliability, the network structure of the distribution network needs to be adjusted. After the network structure is adjusted, the relevant information in the electricity consumption information collection system may not be updated in time, usually through Manually verifying and updating relevant data is time-consuming and labor-intensive.

The applicant of this patent proposes a method for verifying and maintaining the topology of a distribution network (publication number: CN107508297A), which realizes automatic verification and maintenance of the topology of the distribution network by analyzing the similarity of the voltage curve at the outlet of the distribution transformer. is the correlation coefficient. However, the actual operation experience shows that some stations are equipped with voltage adjustment equipment. When it is put into use, the voltage at the outlet of the distribution transformer will rise or drop sharply. At this time, directly calculating the similarity of the voltage curves of the two stations will lead to the calculation result. Inaccurate.

The Chinese patent with publication number CN108564485A (name of invention: phase identification method for low-voltage station users based on voltage curve similarity analysis) proposes a low-voltage station user phase identification method based on the similarity analysis of voltage curves of smart meters. DTW distance to judge the similarity of the voltage curves. The Chinese patent with publication number CN104092481A (name of invention is: a method for distinguishing platform and phase by voltage characteristics), by comparing the similarity between the voltage curve of the undetermined node and the voltage curve recorded by the concentrator, to determine the node Whether it belongs to this station area, and the similarity calculation method is the correlation coefficient method. None of the above-mentioned patents relate to the calculation method of the similarity of the voltage curve which is affected by the voltage adjustment measures.

SUMMARY OF THE INVENTION

The present invention provides a method for calculating the similarity of voltage curves considering the influence of voltage adjustment measures, through which the similarity of voltage curves of two mesas with voltage adjustment measures can be calculated correctly.

The technical scheme adopted in the present invention is:

A voltage curve similarity calculation method considering the influence of voltage adjustment measures, comprising the following steps:

A. Acquisition of distribution transformer related data, the distribution transformer related data includes: the corresponding relationship between the 10kV line and the distribution transformer, the distribution transformer name, the distribution transformer address code, and the distribution transformer three-phase voltage;

B, preprocessing the distribution transformer outlet voltage data obtained in step A;

C, according to the distribution transformer outlet voltage data preprocessed in step B, identify the voltage mutation point, and segment the voltage curve;

D, according to the voltage curve segmentation result of step C, calculate the similarity of the segmented curve;

E. According to the similarity result of the segmented curves calculated in step D, comprehensively judge the similarity of the voltage curves of the two stations.

Further, the preprocessing of the distribution transformer outlet voltage data described in step B is specifically:

The production management system records the three-phase voltage value of the station area for one day, and records one point at a certain time, and the data of N points in total throughout the day. The voltage value of phase A is U _a1 , U _a2 ...... U _aN , and the voltage value of B phase is U a1 , U a2 ...... U aN U _b1 , U _b2 ...... U _bN , the C-phase voltage values are U _c1 , U _c2 ...... U _cN , the following formula is used to calculate the distribution transformer outlet voltage U _i without considering the influence of the three-phase load imbalance:

Among them, U _ai , U _bi , and U _ci are the three-phase voltages of A, B, and C at the i-th point respectively, i=1...N, and U _i is the distribution transformer outlet voltage at the i-th point without considering the influence of the three-phase load imbalance , U _i can be obtained by iterative method.

Further, the voltage mutation point identification method described in step C is:

1) Calculate the voltage difference at the corresponding moment of the two curves; the outlet voltage of the distribution transformer in platform 1 is U _T1i , and the outlet voltage of the distribution transformer in platform 2 is U _T2i , where i=1...96. The voltage difference U _1i at the corresponding moment of the two stations;

U _1i =U _T1i -U _T2i , i=1...96

2) Then calculate the variation of the voltage difference; the variation ΔU _1i of the voltage difference U _1i between the two platforms;

ΔU _1i =U _1(i+1) −U _1i , i=1...95

3) The normality test of the variation is carried out by Kolmogorov-Smirnov. If it obeys the normal distribution, it indicates that there is no mutation point; if it does not obey the normal distribution, it indicates that there is a mutation point;

4) Judge the abnormal point through the box diagram, and identify the position of the voltage mutation point.

Further, calculating the similarity of the segmented curve described in step D is specifically:

Suppose there are two mutation points, and the positions of the mutation points are k ₁ and k ₂ respectively. Since the voltage curve has a total of 96 points, the voltage curve can be divided into three segments according to the positions of the two mutation points [0,k ₁ ),[ k ₁ , k ₂ ), [k ₂ , 96], respectively calculate the similarity S ₁ , S ₂ , and S ₃ of the three voltage curves.

Further, step E comprehensively judges the similarity of the voltage curves of the two stations, specifically: comparing the similarity degrees S ₁ , S ₂ , and S ₃ of the segmental curves calculated in step D, and taking the maximum value as the voltage curves of the two stations similarity.

Based on the historical operation data of the distribution transformer outlet voltage, the invention identifies the mutation point of the outlet voltage curve of the station area with voltage adjustment measures, segments the voltage curve according to the position of the voltage mutation point, and calculates the similarity of the segmented curves, so as to ensure that there is a voltage Correctness of voltage curve similarity calculation when adjusting measures.

Description of drawings

1 is a schematic flowchart of a method for calculating the similarity of voltage curves considering the influence of voltage adjustment measures according to the present invention;

Fig. 2 is a typical two stage outlet voltage curve diagrams involved in the present invention (after preprocessing in step B);

Fig. 3 is the Q-Q diagram of the voltage mutation point detection involved in the present invention;

FIG. 4 is a box diagram of the voltage mutation point detection according to the present invention.

Detailed ways

The technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention.

1 is a schematic flowchart of a method for calculating the similarity of voltage curves considering the influence of voltage adjustment measures according to the present invention, and the method for calculating similarity of voltage curves considering the influence of voltage adjustment measures includes the following steps:

A. Acquisition of distribution transformer related data, the distribution transformer related data includes: the corresponding relationship between the 10kV line and the distribution transformer, the distribution transformer name, the distribution transformer address code, and the distribution transformer three-phase voltage;

B. Preprocess the distribution transformer outlet voltage data obtained in step A

The production management system records the three-phase voltage value of the station area for one day, and records one point at a certain time, with a total of N points of data throughout the day. The voltage value of phase A is U _a1 , U _a2 ...... U _aN , and the voltage value of B phase is U _b1 , U _b2 ...... U _bN , the C-phase voltage values are U _c1 , U _c2 ...... U _cN , the following formula is used to calculate the distribution transformer outlet voltage U _i without considering the influence of the unbalanced three-phase load:

Among them, U _ai , U _bi , and U _ci are the three-phase voltages of A, B, and C at the i-th point respectively, i=1...N, and U _i is the distribution transformer outlet voltage at the i-th point without considering the influence of the three-phase load imbalance , U _i can be obtained by iterative method.

C, according to the distribution transformer outlet voltage data preprocessed in step B, identify the voltage mutation point, and segment the voltage curve;

1) Calculate the voltage difference at the corresponding moment of the two curves; the outlet voltage of the distribution transformer in platform 1 is U _T1i , and the outlet voltage of the distribution transformer in platform 2 is U _T2i , where i=1...96. The voltage difference U _1i at the corresponding moment of the two stations;

U _1i =U _T1i -U _T2i , i=1...96

2) Then calculate the variation of the voltage difference; the variation ΔU _1i of the voltage difference U _1i of the two platforms;

ΔU _1i =U _1(i+1) −U _1i , i=1...95

3) The normality test of the variation is carried out by Kolmogorov-Smirnov. If it obeys the normal distribution, it indicates that there is no mutation point; if it does not obey the normal distribution, it indicates that there is a mutation point;

4) Judge the abnormal point through the box diagram, and identify the position of the voltage mutation point.

D, according to the voltage curve segmentation result of step C, calculate the similarity of the segmented curve

Suppose there are two mutation points, and the positions of the mutation points are k ₁ and k ₂ respectively. Since the voltage curve has a total of 96 points, the voltage curve can be divided into three segments according to the positions of the two mutation points [0,k ₁ ),[ k ₁ , k ₂ ), [k ₂ , 96], respectively calculate the similarity S ₁ , S ₂ , and S ₃ of the three voltage curves.

E. According to the similarity result of the segmented curves calculated in step D, comprehensively judge the similarity of the voltage curves of the two stations. Compare the similarities S ₁ , S ₂ , and S ₃ of the segmented curves calculated in step D, and take the maximum value as the similarity of the voltage curves of the two mesas.

The technical scheme and effect of the present invention are described in detail below with a specific embodiment:

In step A, the output voltage data of the distribution transformers in the two stations (Gongyou Immigration Xincuntai District and Xidaotai District) supplied by the 10kV Gongyouting line were obtained from the relevant system, as shown in the table below for the Xidaotai area. Distribution transformer outlet voltage value:

Table 1 The voltage value of the distribution transformer outlet in the lower platform area on June 1, 2018

In step B, the data of the distribution transformer outlet voltage is preprocessed, and the distribution transformer outlet voltage is calculated without considering the influence of the unbalanced three-phase load, as shown in Figure 2.

In step C, 1) _Calculate the voltage difference between the two _curves at the corresponding time; The voltage difference U _1i at the corresponding moment of the two stations;

U _1i =U _T1i -U _T2i , i=1...96

2) Then calculate the variation of the voltage difference; the variation ΔU _1i of the voltage difference U _1i of the two platforms;

ΔU _1i =U _1(i+1) −U _1i , i=1...95

3) The normality test of the variation is carried out by Kolmogorov-Smirnov, and the normality test of the variation of the voltage difference is carried out. The results are shown in the following table. It can be seen that the p value is 0<0.05, indicating the variation of the voltage difference. It does not obey the normal distribution, indicating that there is a sudden change in the outlet voltage of one of the two stations. The results of the Q-Q plot shown in Figure 3 also show that the normal distribution is not followed.

Table 2 Normality test results

4) Judge the abnormal point through the box diagram, and identify the position of the voltage mutation point. From the box plot shown in Figure 4, it is found that there are two mutation points, which are the 19th and 78th data points (corresponding to the 20th and 79th points of the original data). According to the position of the mutation point, the voltage curve is divided into Three paragraphs, of which 1-19 is the first paragraph, 20-78 is the second paragraph, and 79-96 is the third paragraph.

In step D, the positions of the two mutation points are k ₁ =20 and k ₂ =79 respectively. Therefore, according to the positions of the two mutation points, the voltage curve can be divided into three segments [0, 20), [20, 79), [79,96], the similarity S ₁ , S ₂ , and S ₃ of the three voltage curves are calculated respectively, and the similarity is represented by calculating the correlation coefficient.

Table 3 Correlation coefficient segment calculation results

Calculation results Correlation coefficient overall 0.077 first paragraph 0.76 second paragraph 0.90 third paragraph 0.93

In step E, according to the calculation result of step D, in the segment similarity, the similarity of the third segment is at most 0.93, so the similarity of the two curves is 0.93.

If the method proposed in the present invention is not used to calculate the similarity of the voltage outlet curves of the two stations, the directly calculated similarity of the voltage outlet curves of the two stations is 0.077, and the calculation result is inaccurate, and the method proposed by the present invention is used to calculate The result is accurate.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, All should be covered within the protection scope of the present invention.

Claims (4)

1. a voltage curve similarity calculation method considering the influence of voltage adjustment measures, is characterized in that, comprises the following steps: A. Acquisition of distribution transformer related data, the distribution transformer related data includes: the corresponding relationship between the 10kV line and the distribution transformer, the distribution transformer name, the distribution transformer address code, and the distribution transformer three-phase voltage; B, preprocessing the distribution transformer outlet voltage data obtained in step A; C, according to the distribution transformer outlet voltage data preprocessed in step B, identify the voltage mutation point, and segment the voltage curve; D, according to the voltage curve segmentation result of step C, calculate the similarity of the segmented curve; E, according to the segmental curve similarity result calculated in step D, comprehensively judge the similarity of the voltage curves of the two platforms; The identification voltage mutation point described in step C is specifically: 1) Calculate the voltage difference at the time corresponding to the two curves; the outlet voltage of the distribution transformer in platform 1 is U _T1i , and the outlet voltage of the distribution transformer in platform 2 is U _T2i , where i=1...96, the two platforms correspond to The voltage difference U _1i at the moment: U _1i =U _T1i -U _T2i , i=1...96 2) Then calculate the variation of the voltage difference; the variation of the voltage difference U _1i between the two platforms ΔU _1i : ΔU _1i =U _1(i+1) −U _1i , i=1...95 3) The normality test of the variation is carried out by Kolmogorov-Smirnov. If it obeys the normal distribution, it indicates that there is no mutation point; if it does not obey the normal distribution, it indicates that there is a mutation point; 4) Judge the abnormal point through the box diagram, and identify the position of the voltage mutation point. 2. The voltage curve similarity calculation method considering the influence of voltage adjustment measures as claimed in claim 1, is characterized in that: described in step B, the distribution transformer outlet voltage data obtained in step A is preprocessed, specifically: The production management system records the three-phase voltage value of the station area for one day, and records one point at a certain time, and the data of N points in total throughout the day. The voltage value of phase A is U _a1 , U _a2 ...... U _aN , and the voltage value of B phase is U a1 , U a2 ...... U aN U _b1 , U _b2 ...... U _bN , the C-phase voltage values are U _c1 , U _c2 ...... U _cN , the following formula is used to calculate the distribution transformer outlet voltage U _i without considering the influence of the three-phase load imbalance:

Among them, U _ai , U _bi , and U _ci are the three-phase voltages of A, B, and C at the i-th point respectively, i=1...N, and U _i is the distribution transformer outlet voltage at the i-th point without considering the influence of the three-phase load imbalance , U _i can be obtained by iterative method. 3. The voltage curve similarity calculation method considering the influence of voltage adjustment measures as claimed in claim 1, is characterized in that: the similarity of the calculation segmented curve described in step D is specifically: Suppose there are two mutation points, and the positions of the mutation points are k ₁ and k ₂ respectively. Since the voltage curve has a total of 96 points, the voltage curve is divided into three segments according to the positions of the two mutation points [0, k ₁ ), [k ₁ , k ₂ ), [k ₂ , 96], the similarity S ₁ , S ₂ , and S ₃ of the three voltage curves are calculated respectively. 4. the voltage curve similarity calculation method considering the influence of voltage adjustment measures as claimed in claim 3, it is characterized in that: step E comprehensively judges the similarity of two platform voltage curves, specifically: compare the segment calculated by step D Curve similarity S ₁ , S ₂ , S ₃ , take the maximum value as the voltage curve similarity of the two mesas.

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