Method and system for multi-harmonic source responsibility allocation based on complex correlation coefficient

Abstract

The present disclosure relates to the technical field of power system harmonic analysis, and provides a multi-harmonic source responsibility division method and system based on complex correlation coefficient, which comprises: constructing a linear relationship between harmonic voltage at a point of common coupling and average active power of multiple users; obtaining a time sequence of the voltage at the point of common coupling and a time sequence of active power data of the multiple users, and according to the constructed linear relationship, a sliding analysis is used to screen a sub-sequence with a large complex correlation coefficient between the harmonic voltage and the average active power of each user; a harmonic responsibility division index is constructed and calculated by using the screened sub-sequence, and the change of the harmonic responsibility with time is obtained. According to the change of the complex correlation coefficient with time, a time period with a large background harmonic disturbance is found out, and the error problem caused by the fluctuation of the background harmonic responsibility is avoided. On the basis of considering the size of the user power and the background harmonic responsibility, the change of the harmonic responsibility with time is given by the harmonic responsibility division index, and the accuracy and precision of the division are improved.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of power system harmonic analysis, in particular, to a multi-harmonic source responsibility division method and system based on complex correlation coefficient. BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] With the wide access of new energy and a large number of distributed loads, the power quality problem of modern power system is becoming more and more serious. The traditional power quality analysis method mainly relies on the power grid physical model to analyze, locate and divide the responsibility of power quality transmission path, but the volatility of new energy and load, the two-way transmission of electric energy and other new features in the new type of power system make the traditional physical modeling and analysis become extremely complex. With the wide application of massive detection equipment such as online power quality monitoring terminal, portable power quality tester, power recorder, SCADA, PMU and smart meter, a large amount of data has been accumulated in the power system, and the power quality analysis method based on data analysis provides a new idea for solving the above problems,

[0004] The inventors found that the traditional harmonic responsibility division method cannot fully utilize the existing detection system data, cannot perform accurate long-time-scale responsibility division, and cannot exclude background harmonic interference. Especially, the existing harmonic responsibility division mostly uses harmonic voltage and harmonic current of the interference source branch to divide the harmonic responsibility, which has the disadvantage of needing to use special equipment to measure harmonic voltage and harmonic current of multiple users synchronously, and the engineering application is limited. SUMMARY

[0005] In order to solve the above problems, the present disclosure proposes a multi-harmonic source responsibility division method and system based on complex correlation coefficient, which can be used for responsibility division of harmonic voltage of multiple users to the power grid public connection point, and improves the accuracy of division.

[0006] In order to achieve the above purpose, the present disclosure adopts the following technical solutions:

[0007] One or more embodiments provide a multi-harmonic source responsibility division method based on complex correlation coefficient, including the following steps:

[0008] Divide the harmonic responsibility of the public connection point into user harmonic responsibility and background harmonic responsibility, and construct the linear relationship between the harmonic voltage at the public connection point and the average active power of multiple users;

[0009] The time sequence of the public connection point voltage and the time sequence of the multi-user active power data are acquired, and according to the constructed linear relationship, a sub-sequence in which the complex correlation coefficient of the harmonic voltage and the average active power of each user is greater than a set threshold is screened by using sliding analysis;

[0010] The harmonic responsibility division index is constructed and calculated by using the screened sub-sequence, and the change of the harmonic responsibility over time is obtained.

[0011] One or more embodiments provide a multi-harmonic source responsibility division system based on a complex correlation coefficient, comprising:

[0012] A first construction module configured to divide the harmonic responsibility at the public connection point into user harmonic responsibility and background harmonic responsibility, and to construct a linear relationship between the harmonic voltage at the public connection point and the average active power of a plurality of users;

[0013] A sub-sequence screening module configured to acquire the time sequence of the public connection point voltage and the time sequence of the multi-user active power data, and to screen a sub-sequence in which the complex correlation coefficient of the harmonic voltage and the average active power of each user is greater than a set threshold according to the constructed linear relationship;

[0014] A harmonic responsibility division module configured to construct and calculate a harmonic responsibility division index by using the screened sub-sequence, and to obtain the change of the harmonic responsibility over time.

[0015] An electronic device comprising a memory and a processor, and computer instructions stored on the memory and running on the processor, when the computer instructions are run by the processor, the steps of the above method are completed.

[0016] A computer readable storage medium for storing computer instructions, when the computer instructions are executed by a processor, the steps of the above method are completed.

[0017] Compared with the prior art, the beneficial effects of the present disclosure are:

[0018] In the present disclosure, the correlation between the average active power of a plurality of users and the harmonic voltage is analyzed and calculated based on a complex correlation coefficient, a time period in which the background harmonic disturbance is large is found out according to the size change of the complex correlation coefficient over time, and the error problem caused by the fluctuation of the background harmonic responsibility is avoided, on the basis of considering the size of the user power and the background harmonic responsibility, the harmonic responsibility division index is determined to give the change of the harmonic responsibility over time, and the accuracy and precision of the division are improved.

[0019] Moreover, the harmonic responsibility division is performed by using the public connection point harmonic voltage data and the user average active power data which are easily acquired in the power system, and the investment cost is reduced by avoiding the additional installation of synchronous measurement devices on the branch.

[0020] Advantages of the present disclosure and additional aspects will be more fully understood in view of the following detailed description, from the specific examples. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings, which form a part of the present disclosure, are intended to provide further understanding of the present disclosure and are incorporated herein in

[0022] Figure 1 is a flow chart of the method of dividing of embodiment 1 of the present disclosure;

[0023] Figure 2 is a time series plot of the 5th harmonic voltage containment ratio at the point of common coupling in the example of embodiment 1 of the present disclosure;

[0024] Figure 3 is a time series plot of the average active power of user 1 in the example of embodiment 1 of the present disclosure;

[0025] Figure 4 is a time series plot of the average active power of user 2 in the example of embodiment 1 of the present disclosure;

[0026] Figure 5 is a time series plot of the average active power of user 3 in the example of embodiment 1 of the present disclosure;

[0027] Figure 6 is a plot of the complex correlation coefficient of the point of common coupling and the average active power of users in the example of embodiment 1 of the present disclosure;

[0028] Figure 7 is a plot of the harmonic responsibility of each user in the example of embodiment 1 of the present disclosure. DETAILED DESCRIPTION

[0029] The present disclosure will be further described with reference to the drawings and examples.

[0030] It should be noted that the following detailed description is merely exemplary and is intended to provide further description of the present disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs.

[0031] It is to be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise, and it should also be understood that the terms "comprise" and / or "include" when used in this specification, specify the presence of stated features, steps, operations, devices, components and / or combinations thereof. It should be noted that the various embodiments in the present disclosure and the features in the embodiments can be combined with each other without conflict, and the embodiments will be described in detail below with reference to the accompanying drawings.

[0032] Embodiment 1

[0033] In the technical solutions disclosed in one or more embodiments, as shown in the drawings, a multi-harmonic source responsibility division method based on complex correlation coefficient includes the following steps: Figures 1-7

[0034] Step 1, dividing the harmonic responsibility at the point of common coupling into user harmonic responsibility and background harmonic responsibility, and constructing a linear relationship between the harmonic voltage at the point of common coupling and the average active power of multiple users;

[0035] Step 2, obtaining the voltage data at the point of common coupling and the active power data of multiple users, according to the constructed linear relationship, using complex correlation coefficient to perform sliding analysis on the sequence data, and screening out a subsequence in which the complex correlation coefficient between the harmonic voltage and the average active power of each user is greater than a set threshold, as a time period in which the background harmonic disturbance is small;

[0036] Step 3, using the screened subsequence to construct and calculate a harmonic responsibility division index, and obtaining the change of the harmonic responsibility over time.

[0037] In this embodiment, the correlation between the average active power of multiple users and the harmonic voltage is analyzed and calculated based on the complex correlation coefficient, and the time period in which the background harmonic disturbance is large is found according to the size change of the complex correlation coefficient over time, thereby avoiding the error problem caused by the fluctuation of the background harmonic responsibility. On the basis of considering the size of the user power and the background harmonic responsibility, the harmonic responsibility division index is determined to give the change of the harmonic responsibility over time.

[0038] In some embodiments, the harmonic responsibility at the point of common coupling is divided as follows:

[0039] Step 11, according to the fact that the average active power of the fundamental wave is much greater than the average active power of the harmonic, the harmonic current is estimated by using the fundamental wave current, and the relationship between the average active power of the user and the harmonic current is obtained;

[0040] Step 12, according to the relationship between the average active power of the user and the harmonic current, the linear relationship between the harmonic voltage at the point of common coupling and the average active power of multiple users is obtained. ​

[0041] According to the superposition principle, the harmonic voltage at the point of common coupling (PCC) is the sum of the harmonic voltage contributions from the system side and the customer side, where the system side harmonic is the background harmonic, which can be expressed as:

[0042]

[0043] where U ih is the hth harmonic voltage of the i th customer, n represents the number of customers, and U0 is the background harmonic voltage.

[0044] Generally, the harmonic impedance of the customer side is much larger than that of the system side, and the flow direction of the harmonic current is from the customer side to the system side. The harmonic voltage at the PCC can be expressed as:

[0045]

[0046] where U PCCh is the hth harmonic voltage at the PCC, Z ih is the hth harmonic impedance of the i th customer, and I ih is the effective value of the hth harmonic current of the customer.

[0047] Considering that the average active power of the fundamental wave of the customer is much larger than the average active power of the harmonic, the power quality analysis estimates the harmonic current using the fundamental current, and the average active power of the customer is expressed as:

[0048]

[0049] where U i1 is the effective value of the fundamental voltage of the customer, I ih is the effective value of the hth harmonic current of the customer, and is the fundamental power factor angle.

[0050] The linear relationship between the harmonic voltage at the PCC and the average active power of the customer can be constructed as follows:

[0051]

[0052] where

[0053] It can be seen that the change rule of the harmonic voltage at the PCC and the average active power of the customer is that the larger the average active power of the nonlinear load, the larger the harmonic voltage at the PCC, and the relationship is linear.

[0054] In step 2, the sub-sequence with a high complex correlation coefficient of harmonic voltage and average active power of each user is screened, the time sequence data of the public connection point voltage and the time sequence data of the active power of multiple users are obtained, the time sequence data is divided into a plurality of sub-sequences by using the sliding analysis method, the complex correlation coefficient of the harmonic voltage sub-sequence and the average active power sub-sequence of each user in the corresponding time period is calculated, and the sub-sequence with a complex correlation coefficient greater than a set threshold is screened out. The specific method comprises the following steps:

[0055] (2-1) Obtain the harmonic voltage data U of the public connection point in a set time period pcc and the average active power data P of each user h to form a time sequence.

[0056] (2-2) Set a sliding window.

[0057] Specifically, the length of the sliding window is L, and the single moving distance is T. The length of T can be 1 / 4 of L.

[0058] (2-3) According to the linear relationship between the harmonic voltage at the public connection point and the average active power of the user, the harmonic voltage at the public connection point is used to regress the average active power of each user in a sliding window, and the following formula is obtained:

[0059]

[0060] Wherein, is the regression coefficient.

[0061] (2-4) According to the regression analysis result, the complex correlation coefficient of the harmonic voltage at the public connection point and the average active power of each user in the sliding window is calculated.

[0062] The complex correlation coefficient is the covariance of the harmonic voltage time sequence in the sliding window and the regression sequence, divided by the product of the standard deviation of the time sequence data in the sliding window and the standard deviation of the regression sequence data. The formula is as follows:

[0063]

[0064] Wherein, is the mean of the U PCCh sequence, is the mean of the P sequence.

[0065] The complex correlation coefficient used in this embodiment can accurately calculate the correlation between one variable and multiple variables, and can more accurately analyze and calculate the correlation between the average active power of multiple users and the harmonic voltage, and then calculate the harmonic responsibility of each user.

[0066] (2-5) Move the sliding window one unit length T, repeat steps (2-3) and (2-4) until the sliding window covers the entire time series.

[0067] (2-6) Screen out the sub-sequence with the complex correlation coefficient greater than the set threshold value, and the number of sub-sequences is M. In this embodiment, the threshold value of the complex correlation coefficient can be set to 0.9.

[0068] In this embodiment, the harmonic responsibility is divided by using the public connection point voltage data and the user active power data, and the user active power data can be obtained from the existing electric meter of each user, so that the additional installation of synchronous measurement devices at each user or each branch is avoided, and the practicability is higher.

[0069] The greater the complex correlation coefficient is, the greater the correlation between the public connection point harmonic voltage and the user active power is, and the smaller the background harmonic disturbance is. In order to exclude the influence of the background harmonic, in the sliding analysis, the sub-sequence with the complex correlation coefficient between the harmonic voltage and the average active power of each user greater than the set threshold value is screened out for harmonic responsibility division.

[0070] The correlation between a single harmonic interference source and the harmonic voltage cannot exclude the influence of the background harmonic disturbance, in this embodiment, the correlation between the average active power of multiple users and the harmonic voltage is analyzed and calculated based on the complex correlation coefficient, and according to the size change of the complex correlation coefficient over time, the time period with small background harmonic disturbance can be found, and the error problem caused by the fluctuation of the background harmonic responsibility is avoided.

[0071] In step 3, the harmonic responsibility division index is constructed and calculated according to the remaining sub-sequences after screening, and the specific method includes:

[0072] (3-1) According to the complex correlation coefficient, the background harmonic responsibility is determined, and the sub-sequence with large background harmonic responsibility is screened out;

[0073] The dynamic background harmonic responsibility of the kth sub-sequence in the corresponding time period after screening is:

[0074] H 0,k =1-R k (7)

[0075] Wherein, k ∈ (1, 2, …, M), R k is the complex correlation coefficient between the hth harmonic voltage at the public connection point and the average active power of each user in the kth sub-sequence.

[0076] (3-2) In the screened sub-sequence, according to the average active power of each sub-sequence and the corresponding regression coefficient, the harmonic responsibility of each time period of the user is determined.

[0077] The harmonic responsibility A k,i of the user i in the kth time period is calculated according to the following formula:

[0078]

[0079] where P k,i represents the average active power of the i-th user in the k-th sub-sequence, is the regression coefficient of the i-th user active power in the k-th sub-sequence obtained by formula (5).

[0080] To illustrate the effect of the method of the embodiment, a specific example is given for illustration.

[0081] The power quality detection data of a 10kV bus of a 110kV substation and the users connected to the bus are obtained for analysis. The actual monitoring data includes 10kV bus harmonic voltage data of the power quality monitoring system and average active power data of each user in the power utilization information acquisition system, and the data time length is 2d. The 5th harmonic voltage data is selected as the analysis object, and the data interval is 3min. For example, Figure 2 is the time series of the 5th harmonic voltage containing rate of the point of common coupling. Figures 3-5 The average active power time series of three users are provided respectively.

[0082] In order to select waveforms with high similarity, the length unit L of the sliding window is set to 10 and the sliding distance unit T is set to 4 in this example.

[0083] In the sliding window, the average active power sequence of each user is regressed by using the harmonic voltage sequence of the point of common coupling, and the complex correlation coefficient is calculated according to formula (6). The complex correlation coefficient of the point of common coupling and the average active power of the user is shown in Figure 6 .

[0084] The sliding window moves back by 4 sampling points, and the complex correlation coefficient calculation is repeated. Until the whole time sequence is covered by the sliding window. The sub-sequences with complex correlation coefficient greater than 0.9 are selected.

[0085] In each sub-sequence, the index A k is calculated, and the proportion of each user in the total harmonic of all analysis users can be calculated according to formulas (8) and (9). As shown in Figure 7 , the proportion of harmonic responsibility of different users in different time periods can be obtained, and the harmonic responsibility can be more finely divided.

[0086] The traditional harmonic responsibility division method has the following limitations: first, the engineering application is limited, and it is difficult to obtain harmonic current data of each interference source; second, the background harmonic responsibility is not considered, and the change of the harmonic responsibility over time cannot be analyzed. The harmonic responsibility division index of the embodiment considers the user power size and the background harmonic responsibility to determine the harmonic responsibility of each time period of the user, gives the change of the harmonic responsibility over time, and improves the accuracy and accuracy of the harmonic responsibility division.

[0087] Embodiment 2

[0088] Based on embodiment 1, the multi-harmonic source responsibility division system based on complex correlation coefficient is provided in the embodiment, which comprises:

[0089] The first construction module is configured to divide the point of common coupling harmonic responsibility into user harmonic responsibility and background harmonic responsibility, and construct the linear relationship between the harmonic voltage at the point of common coupling and the average active power of the plurality of users;

[0090] The sub-sequence screening module is configured to obtain the point of common coupling voltage time sequence and the plurality of user active power data time sequences, and screen the sub-sequences with the complex correlation coefficient between the harmonic voltage and the average active power of each user greater than the set threshold according to the constructed linear relationship;

[0091] The harmonic responsibility division module is configured to construct and calculate the harmonic responsibility division index using the screened sub-sequences, and obtain the change of the harmonic responsibility over time.

[0092] It should be noted that each module in the embodiment corresponds to each step in embodiment 1, and the specific implementation process is the same, which will not be repeated here.

[0093] Embodiment 3

[0094] The embodiment provides an electronic device, which comprises a memory and a processor, and computer instructions stored in the memory and running on the processor, when the computer instructions are run by the processor, the steps of the method of embodiment 1 are completed.

[0095] Embodiment 4

[0096] The embodiment provides a computer readable storage medium for storing computer instructions, when the computer instructions are executed by the processor, the steps of the method of embodiment 1 are completed.

[0097] The above only describes the preferred embodiments of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

[0098] Although the specific embodiments of the present disclosure are described above with reference to the drawings, the description is not a limitation to the scope of protection of the present disclosure, and those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present disclosure without creative labor are still within the scope of protection of the present disclosure.

Claims

1. A method for multi-harmonic source responsibility allocation based on complex correlation coefficient, characterized in that, The method comprises the following steps: The harmonic responsibility at the point of common coupling is divided into user harmonic responsibility and background harmonic responsibility, and a linear relationship between the harmonic voltage at the point of common coupling and the average active power of multiple users is constructed; The time sequence of the voltage at the point of common coupling and the time sequence of the active power data of multiple users are obtained, and according to the constructed linear relationship, a sliding analysis is used to screen the sub-sequences in which the complex correlation coefficient between the harmonic voltage and the average active power of each user is greater than a set threshold value; The method for calculating the complex correlation coefficient between the harmonic voltage at the point of common coupling and the average active power of each user in each sliding window comprises the following steps: According to the linear relationship between the harmonic voltage at the point of common coupling and the average active power of each user, the harmonic voltage at the point of common coupling is used to regress the average active power of each user in a sliding window; According to the regression analysis result, the complex correlation coefficient between the harmonic voltage at the point of common coupling and the average active power of each user in the sliding window is calculated; The complex correlation coefficient is the quotient of the covariance between the time sequence of the harmonic voltage in the sliding window and the regression sequence, divided by the product of the standard deviation of the time sequence data in the sliding window and the standard deviation of the regression sequence data; The complex correlation coefficient can accurately calculate the correlation between one variable and multiple variables, and can more accurately analyze and calculate the correlation between the average active power of multiple users and the harmonic voltage, and then calculate the harmonic responsibility of each user. The harmonic responsibility division index is constructed and calculated by using the screened sub-sequences, and the change of the harmonic responsibility over time is obtained.

2. The method of claim 1, wherein: The harmonic voltage at the point of common coupling is the sum of the contribution of the system side harmonic voltage and the user side harmonic voltage, wherein the system side harmonic is the background harmonic.

3. The complex correlation coefficient based multi-harmonic source apportionment method as claimed in claim 1, wherein, The method for constructing the linear relationship between the harmonic voltage at the point of common coupling and the average active power of multiple users comprises: According to the fact that the average active power of the fundamental wave of a user is much greater than the average active power of the harmonic, the harmonic current is estimated by using the fundamental wave current, and the relationship between the average active power of the user and the harmonic current is obtained; According to the relationship between the average active power of the user and the harmonic current, the linear relationship between the harmonic voltage at the point of common coupling and the average active power of multiple users is obtained.

4. The method for dividing the responsibility of multiple harmonic sources based on the complex correlation coefficient according to claim 1, wherein: The sub-sequences with high complex correlation coefficient between the harmonic voltage and the average active power of each user are screened out, and the specific method comprises: The harmonic voltage data at the point of common coupling and the average active power data of each user in a set time period are obtained to form time sequences; A sliding window is set, and the complex correlation coefficient between the harmonic voltage at the point of common coupling and the average active power of each user in the sliding window is calculated until the sliding window covers the entire time sequence; The sub-sequences with complex correlation coefficient greater than a set threshold value are screened out.

5. The method for dividing the responsibility of multiple harmonic sources based on the complex correlation coefficient according to claim 1, wherein: The length of the sliding window is set to L , and the single moving distance is T , T The length of the sliding window can be 1 / 4 of L .

6. The method for dividing the responsibility of multiple harmonic sources based on the complex correlation coefficient according to claim 1, wherein: The method for constructing and calculating the harmonic responsibility division index according to the remaining sub-sequences after screening comprises: The background harmonic responsibility is determined according to the complex correlation coefficient, and the sub-sequences with large background harmonic responsibility are screened out. Among the screened subsequences, the harmonic responsibility of each user in each time period is determined according to the average active power of each subsequence and the corresponding regression coefficient.

7. A multi-harmonic source responsibility allocation system based on complex correlation coefficient using the method as claimed in claim 1, characterized in that, The method comprises the following steps: A first constructing module is configured to divide the harmonic responsibility of the point of common coupling into the harmonic responsibility of the user and the harmonic responsibility of the background, and to construct a linear relationship between the harmonic voltage at the point of common coupling and the average active power of the plurality of users; A subsequence screening module is configured to obtain a time sequence of the voltage at the point of common coupling and a time sequence of the active power data of the plurality of users, and to screen, according to the constructed linear relationship, a subsequence in which the complex correlation coefficient between the harmonic voltage and the average active power of each user is greater than a set threshold value by using sliding analysis; A harmonic responsibility dividing module is configured to construct and calculate a harmonic responsibility dividing index by using the screened subsequence, and to obtain the change of the harmonic responsibility over time.

8. An electronic device, comprising: The computer program product comprises a memory and a processor, and computer instructions stored in the memory and run on the processor, and when the computer instructions are run by the processor, the steps of the method in any one of claims 1-6 are completed.

9. A computer-readable storage medium, characterized in that, The computer program product is used for storing computer instructions, and when the computer instructions are executed by the processor, the steps of the method in any one of claims 1-6 are completed.

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