Power distribution network fault positioning method based on branch response data

Abstract

The invention belongs to the technical field of fault positioning, and provides a power distribution network fault positioning method based on branch response data. Comprising the following steps: step 1, detecting each fault response characteristic parameter in a power distribution network system according to a measurement sequence by using a detection unit and storing data; step 2, extracting response data strongly related to fault positioning, including extracting U / I response characteristic quantity of each branch and performing differential processing to obtain a U / I response parameter change rate function at two ends of each branch; the invention discloses a power distribution network fault positioning method based on branch response data by researching response characteristics of a power distribution network after a short-circuit fault. The fault response information of branches is extracted through a wide area measurement system, and the mapping correlation between various branch responses and short circuit faults at different fault positions is analyzed to obtain key response information. And a set of fault branch screening strategy is constructed, so that false fault areas which may cause misjudgment are effectively eliminated, and the effective response information density is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fault location and proposes a distribution network fault location method based on branch response data. Background Art

[0002] Damage to electrical equipment in the distribution network, extreme weather, and man-made accidents may all lead to short-circuit faults. Timely and reliable determination of the fault location is of great significance for reducing the economic losses caused by power outages and improving the reliability of the power grid. The present invention addresses the problem of timely determination of the fault location after a short-circuit fault occurs in the distribution network, and proposes an innovative fault location method. The method is based on branch response data and introduces the short-circuit current coefficient into the fault location formula. Combined with the wide-area measurement system, the key response data at both ends of the branch are efficiently extracted. A set of sophisticated fault branch screening strategies is established to effectively eliminate pseudo-fault areas that may cause misjudgment, thereby increasing the concentration of effective response information. This method significantly enhances the accuracy and universality of fault location, and can still ensure the accuracy of fault location even under different working conditions such as changes in branch parameters, complexity of fault types, and access to new energy. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a practical method for locating distribution network faults under different complex working conditions, which includes three parts: feature extraction, fault de-false detection and fault identification. In the feature extraction part, the key response information is obtained by adopting the electrical quantity data feature screening factor. In the fault de-false detection part, the branch current expression is simplified by combining the short-circuit current change characteristics at the moment of the fault. The key response information for fault de-false detection is formed by using the short-circuit current change rate signal at the head end of the branch, and the U / I response change rate function at the same end of the branch is defined. The fault de-false detection is completed based on the change rate characteristics of the fault branch. In the fault identification part, the short-circuit current distribution coefficient is introduced based on the key response information at both ends of the branch, and a proportional coefficient formula for the specific location where the short-circuit fault occurs is constructed, and finally the identification result of the fault location is output. It includes the following steps, and the following steps are performed in sequence:

[0004] 1) Extraction of key response data that is strongly related to fault location

[0005] Step 1: Using a typical power system as an example, construct an equivalent circuit diagram to simulate a short-circuit fault in an actual system. Using the PSCAD platform, build a simulation model, set a ground short-circuit fault stimulus, and obtain response data for various branches at different fault locations.

[0006] Step 2: Calculate the distance D of the j-th response data in the i-th state ij , and solve the average intra-class distance D of the j-th class response data j and the mean Q of the j-th response data in the i-th state ij ;

[0007] Step 3: Q ij The average inter-class distance D'j of the j-th response data in all state categories can be obtained. According to the intra-class distance of the j-th response data, the discrimination factor β of the j-th response data is defined. ab j and the j-th type response data feature screening factor β j ;

[0008] Step 4: Filter the factor β by analyzing the characteristics of various branch response data at different fault locations j , the correlation between each fault response and short-circuit fault mapping is obtained, and the voltage and current are evaluated as key response information;

[0009] 2) Establish a fault location method based on branch response information

[0010] Step 1: The voltage expression of the branch short-circuit point is:

[0011]

[0012] Where: and is the short-circuit point voltage calculated from the response parameters at the left and right ends of the branch, are the bus voltages at the left and right ends of the branch, are the bus voltages at the left and right ends of the branch, is the impedance from the left bus to the fault point, and Z Q is the total branch impedance;

[0013] Step 2: Under the premise that the response data is accurately synchronized, the fault point voltages calculated from the response data on both sides of the branch are equal, that is:

[0014]

[0015] In a branch circuit where only impedance parameters are used to represent the equivalent circuit, when a short circuit fault occurs at a certain point in the branch circuit, the sum of the currents flowing into both sides of the branch circuit can be considered as the short circuit current at the fault point. F When the short-circuit current distribution coefficient C on both sides of the fault branch is L 、C R for:

[0016]

[0017] Step 3: The proportional coefficient k of the specific location where the short-circuit fault occurs can be obtained by using the short-circuit current distribution coefficient on both sides of the fault branch and the branch short-circuit point voltage expression:

[0018]

[0019] 3) Fault area de-falsification based on branch side response information

[0020] Step 1: At the moment of fault occurrence, the DC component of the short-circuit current is extremely small and can be ignored. Simplify the branch current expression to:

[0021]

[0022] Where I is the branch current, is the amplitude of the AC component of the short-circuit current; f is the system frequency; t is the fault time; θ is the initial phase;

[0023] Step 2: Use the short-circuit current change rate signal at the head end of the branch to form key response information and define the U / I response change rate function ξ(x, y) at the same end of the branch;

[0024]

[0025] Where: I1-I n is the current flowing into the n branch lines; U1-U n is the voltage at the same end; I Fai , U Fai is the current flowing into the fault branch line section and the voltage at the same end; ξ"(x,y) is the rate of change function corresponding to the fault branch;

[0026] Step 3: Calculate the change rate function value based on the key response information of n branches in the system. The change rate of the current flowing into the fault branch line is dI f / dt>0, the voltage response change rate at the same end is dU f / dt<0, and the U / I change rate of the fault branch is the largest. This rule is used to screen the fault branch.

[0027] 4) A distribution network fault location method based on branch response data

[0028] Step 1: Using the detection unit to detect each fault response characteristic parameter in the system in accordance with the measurement sequence and store the data;

[0029] Step 2: Extract the U / I response characteristic of each branch and perform differential processing to obtain the U / I response parameter change rate at both ends of each branch;

[0030] Step 3: Determine whether the fault branch screening index satisfies ξ"(x, y) to screen the fault branch;

[0031] Step 4: After accurately determining the faulty branch, screen and extract the U / I response parameters of both ends of the faulty branch and perform normalization on the data;

[0032] Step 5: Accurately locate the fault based on the specific parameters of the branch circuit so that the information can be fed back to the relevant maintenance personnel for the next step of troubleshooting.

[0033] The beneficial effects of the present application are as follows: the present application studies the response characteristics of the distribution network after a short-circuit fault and derives a distribution network fault location method based on branch response data. The fault response information of the branch is extracted through a wide-area measurement system, and the correlation between the various branch responses and the short-circuit fault mapping at different fault locations is analyzed to obtain key response information. A set of fault branch screening strategies is constructed to effectively eliminate pseudo-fault areas that may lead to misjudgment and improve the density of effective response information. The accuracy and applicability of fault location are significantly improved, and the present invention can also achieve precise positioning for different branches with changes in branch parameters, changes in fault types, and access to new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0035] Figure 1 This is the flow chart for locating faults in distribution network branches. DETAILED DESCRIPTION

[0036] The present invention provides a distribution network fault location method based on branch response data, such as Figure 1 As shown, the following steps are included:

[0037] 1) Extraction of key response data that is strongly related to fault location

[0038] Step 1: Using a typical power system as an example, construct an equivalent circuit diagram to simulate a short-circuit fault in an actual system. Using the PSCAD platform, build a simulation model, set a ground short-circuit fault stimulus, and obtain response data for various branches at different fault locations.

[0039] Step 2: Calculate the distance D of the j-th response data in the i-th state ij , and solve the average intra-class distance D of the j-th class response data j and the mean Q of the j-th response data in the i-th state ij ;

[0040] Step 3: Q ij The average inter-class distance D'j of the j-th response data in all state categories can be obtained. According to the intra-class distance of the j-th response data, the discrimination factor β of the j-th response data is defined. ab j and the j-th type response data feature screening factor β j ;

[0041] Step 4: Filter the factor β by analyzing the characteristics of various branch response data at different fault locations j , the correlation between each fault response and short-circuit fault mapping is obtained, and the voltage and current are evaluated as key response information;

[0042] 2) Establish a fault location method based on branch response information

[0043] Step 1: The voltage expression of the branch short-circuit point is:

[0044]

[0045] Where: and is the short-circuit point voltage calculated from the response parameters at the left and right ends of the branch, are the bus voltages at the left and right ends of the branch, are the bus voltages at the left and right ends of the branch, is the impedance from the left bus to the fault point, and Z Q is the total branch impedance;

[0046] Step 2: Under the premise that the response data is accurately synchronized, the fault point voltages calculated from the response data on both sides of the branch are equal, that is:

[0047]

[0048] In a branch circuit where only impedance parameters are used to represent the equivalent circuit, when a short circuit fault occurs at a certain point in the branch circuit, the sum of the currents flowing into both sides of the branch circuit can be considered as the short circuit current at the fault point. F When the short-circuit current distribution coefficient C on both sides of the fault branch is L 、C R for:

[0049]

[0050] Step 3: The proportional coefficient k of the specific location where the short-circuit fault occurs can be obtained by using the short-circuit current distribution coefficient on both sides of the fault branch and the branch short-circuit point voltage expression:

[0051]

[0052] 3) Fault area de-falsification based on branch side response information

[0053] Step 1: At the moment of fault occurrence, the DC component of the short-circuit current is extremely small and can be ignored. Simplify the branch current expression to:

[0054]

[0055] Where I is the branch current, is the amplitude of the AC component of the short-circuit current; f is the system frequency; t is the fault time; θ is the initial phase;

[0056] Step 2: Use the short-circuit current change rate signal at the head end of the branch to form key response information and define the U / I response change rate function ξ(x, y) at the same end of the branch;

[0057]

[0058] Where: I1-I n is the current flowing into the n branch lines; U1-U n is the voltage at the same end; I Fai , U Fai is the current flowing into the fault branch line section and the voltage at the same end; ξ"(x,y) is the rate of change function corresponding to the fault branch;

[0059] Step 3: Calculate the change rate function value based on the key response information of n branches in the system. The change rate of the current flowing into the fault branch line is dI f / dt>0, the voltage response change rate at the same end is dU f / dt<0, and the U / I change rate of the fault branch is the largest. This rule is used to screen the fault branch.

[0060] 4) A distribution network fault location method based on branch response data

[0061] Step 1: Using the detection unit to detect each fault response characteristic parameter in the system in accordance with the measurement sequence and store the data;

[0062] Step 2: Extract the U / I response characteristic of each branch and perform differential processing to obtain the U / I response parameter change rate at both ends of each branch;

[0063] Step 3: Determine whether the fault branch screening index satisfies ξ"(x, y) to screen the fault branch;

[0064] Step 4: After accurately determining the faulty branch, screen and extract the U / I response parameters of both ends of the faulty branch and perform normalization on the data;

[0065] Step 5: Accurately locate the fault based on the specific parameters of the branch circuit so that the information can be fed back to the relevant maintenance personnel for the next step of troubleshooting.

[0066] It should be understood by those skilled in the art that the above embodiments are merely for the purpose of illustrating the present invention clearly, and are not intended to limit the scope of the present invention. For those skilled in the art, other changes or modifications may be made based on the above invention, and these changes or modifications are still within the scope of the present invention.

Claims

1. A distribution network fault location method based on branch response data, characterized in that ,Using branch real-time response data to realize fault location includes the following steps: Step 1: Using the detection unit to detect each fault response characteristic parameter in the distribution network system in accordance with the measurement sequence and store the data; Step 2: extracting response data that is strongly correlated with fault location, including extracting the U / I response characteristic of each branch and performing differential processing to obtain the U / I response parameter change rate function at both ends of each branch; Step 3: Based on the branch response information fault location judgment method, determine whether the U / I response change rate functions of the n faulty branches meet the U / I change rate function ξ"(x,y) corresponding to the faulty branch to screen the faulty branch; Step 4: After accurately determining the faulty branch, screen and extract the U / I response parameters at both ends of the faulty branch, normalize the data, and accurately locate the fault based on the specific parameters of the branch.

2. The distribution network fault location method based on branch response data according to claim 1, characterized in that: Extracting response data that is strongly relevant to fault location includes the following steps: 1) Build a simulation model based on the PSCAD platform, set the ground short circuit fault excitation, and obtain the response data of various branches under different fault locations; 2) Calculate the distance D of the j-th response data in the i-th state ij , and solve the average intra-class distance D of the j-th class response data j and the mean Q of the j-th response data in the i-th state ij ; 3) By the mean Q ij The average inter-class distance D'j of the j-th response data in all state categories can be obtained. According to the intra-class distance of the j-th response data, the discrimination factor β of the j-th response data is defined. ab j and the j-th type response data feature screening factor β j ; 4) By analyzing the characteristic screening factor β of various branch response data at different fault locations j , the correlation between each fault response and short-circuit fault mapping is obtained, and the voltage or current is evaluated as the key response information.

3. The distribution network fault location method based on branch response data according to claim 1, characterized in that: Fault location methods based on branch response information include: (1) The voltage expression of the branch short-circuit point is: Where: and is the short-circuit point voltage calculated from the response parameters at the left and right ends of the branch, are the bus voltages at the left and right ends of the branch, are the bus voltages at the left and right ends of the branch, is the impedance from the left bus to the fault point, and Z Q is the total branch impedance; (2) Under the premise that the response data is accurate, the fault point voltage calculated from the response data on both sides of the branch is equal, that is: In a branch circuit where only impedance parameters are used to represent the equivalent circuit, when a short circuit fault occurs at a certain point in the branch circuit, the sum of the currents flowing into both sides of the branch circuit can be considered as the short circuit current at the fault point. F When the short-circuit current distribution coefficient C on both sides of the fault branch is L 、C R for: (3) The proportional coefficient k of the specific location where the short-circuit fault occurs can be obtained by the short-circuit current distribution coefficient on both sides of the fault branch and the voltage expression of the branch short-circuit point:

4. The distribution network fault location method based on branch response data according to claim 3 is characterized in that ,,Determining whether the fault branch index satisfies the change rate function ξ"(x,y) corresponding to the fault branch to screen the fault branch includes the following steps: a. Based on the fact that the DC component of the short-circuit current is extremely small and negligible at the moment of fault occurrence, the branch current expression is simplified to: Where I is the branch current, is the amplitude of the AC component of the short-circuit current; f is the system frequency; t is the fault time; θ is the initial phase; b. Use the short-circuit current change rate signal at the head end of the branch to form key response information and define the U / I response change rate function ξ(x, y) at the same end of the branch; Where: I1-I n is the current flowing into the n branch lines; U1-U n is the voltage at the same end; I Fai , U Fai is the current flowing into the fault branch line section and the voltage at the same end; ξ"(x,y) is the rate of change function corresponding to the fault branch; c. Calculate the change rate function value based on the key response information of n branches in the system. The change rate of the current flowing into the fault branch line is dI f / dt>0, the voltage response change rate at the same end is dU f / dt<0, and the U / I change rate of the fault branch is the largest. This rule is used to screen the fault branch.

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