Active distribution network traveling wave fault location method under power electronic device disturbance

Abstract

The present invention provides an active distribution network traveling wave fault location method under the disturbance of power electronic devices. The method first uses the power electronic device of the substation to generate the traveling wave waveform under the active disturbance mode, and records the traveling wave waveform at the starting node and the end node of the distribution line; then uses the power electronic device at the end of the branch line to generate the traveling wave waveform under the active disturbance mode; then, extracts the time when the head of the above-mentioned active disturbance type downward wave arrives at the starting end and the end node of the distribution line, and calculates the distribution line parameters; once a fault occurs, records the fault transient traveling wave waveform obtained at the starting end and the end node of the distribution line, extracts the arrival time, and carries out the distribution line fault traveling wave section location and locates the fault position accordingly. The present invention avoids the influence of the missing or error of the distribution line parameters on the fault location, and improves the accuracy of the distribution line traveling wave fault location method.

Description

Technical Field

[0001] The invention relates to the technical field of distribution network relay protection, and in particular to an active distribution network traveling wave fault locating method under the disturbance of a power electronic device. Background Art

[0002] Once a distribution network with multiple branches and complex topology fails, it is difficult for operation and maintenance personnel to determine the fault location in time, which affects the troubleshooting and power supply restoration process of on-site operation and maintenance personnel, resulting in a decrease in power supply reliability. Therefore, reliable and accurate fault location technology is crucial for distribution network self-healing.

[0003] The traveling wave fault location method uses the time difference between the high-frequency transient traveling wave head generated by the fault and the traveling wave sensor to achieve fault location. It has high positioning accuracy and has been widely used in high-voltage transmission networks. Due to the large number of distribution line branches and complex topological structures, the length parameters of overhead lines and cable lines in the distribution lines are missing or have large errors. The fault line mode traveling wave will be refracted and reflected multiple times during transmission in the distribution line. The fault location result achieved by relying solely on the time difference between the traveling wave generated by the fault arriving at the starting node and the end node of the distribution line will have a very large deviation. Therefore, it is necessary to rely on new input signals to correct the distribution line fault traveling wave location and improve the accuracy of distribution network traveling wave fault location. Summary of the invention

[0004] The purpose of the present invention is to provide an active distribution network traveling wave fault location method under power electronic device disturbance in view of the above-mentioned problems existing in the prior art.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] An active distribution network traveling wave fault location method under power electronic device disturbance comprises the following steps:

[0007] Step A, using a controllable arc suppression coil at a substation grounding transformer or a power electronic device in a controllable capacitor compensator at a busbar to generate a traveling wave waveform under active disturbance mode, and recording the traveling wave waveform at the starting end node and the end node of the distribution line;

[0008] Step B, using the power electronic device in the controllable capacitor compensator at the distribution transformer at the end of the branch line to generate a traveling wave waveform under active disturbance mode, and recording the traveling wave waveform at the starting end node and the end node of the distribution line;

[0009] Step C, extracting the arrival time of the traveling wave head according to the traveling wave waveforms at the starting node and the end node of the distribution line obtained in step A and step B, and calculating the parameters of each section of the distribution line;

[0010] Step D: Once a fault occurs, the fault location is achieved through the arrival time of the traveling wave head recorded by the starting and ending nodes of the distribution line, and the parameters of each section of the distribution line obtained in step C.

[0011] In step A, the controllable arc suppression coil at the grounding transformer of the substation or the power electronic device in the controllable capacitor compensator at the busbar is used to generate a traveling wave waveform under active disturbance mode, and the traveling wave waveforms at the starting end node and the end node of the distribution line are recorded, as follows:

[0012] Step A1-1, adjusting the electronic device in the controllable arc suppression coil at the grounding transformer of the substation or the controllable capacitor compensator at the busbar to change the equivalent reactance at the substation;

[0013] Step A1-2, record the traveling wave waveform of the starting node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the starting node at the first mutation point time t 1,1 ;

[0014] Step A1-3, record the traveling wave waveform of the terminal node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the terminal node at the first mutation point time t 2,1 .

[0015] Step B: using the power electronic device in the controllable capacitor compensator at the distribution transformer at the end of the branch line to generate a traveling wave waveform under active disturbance mode, and recording the traveling wave waveform at the starting end node and the end node of the distribution line, as follows;

[0016] Step B1-1: Use branch line P m The power electronic device in the controllable capacitor compensator at the terminal distribution transformer changes the equivalent reactance at the substation at the end of the branch line. m A branch line connected to a node m on the line from the starting node to the terminal node of the distribution line;

[0017] Step B1-2, record the traveling wave waveform of the starting node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the starting node at the time corresponding to the first mutation point

[0018] Step B1-3, record the traveling wave waveform of the terminal node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the terminal node at the time corresponding to the first mutation point

[0019] Step B1-4, repeat B1-1 to B1-3 until the moment when the traveling waves generated by the disturbance at the end of all branch lines reach the starting end node and the end node of the distribution line is obtained.

[0020] Step C: extract the arrival time of the traveling wave head according to the traveling wave waveforms at the starting node and the end node of the distribution line obtained in step A and step B, and calculate the parameters of each section of the distribution line, as follows:

[0021] Step C1-1, divide the distribution line into sections according to branch nodes, overhead-cable connection points, etc., from the starting node to the end node of the distribution line, divided into n sections, the length of the i-th section is l i , of type x i , x i =0 represents overhead line, x i =1 represents a cable line, the starting node of the i-th section is numbered i-1, and its end node is i;

[0022] Step C1-2: According to the results of step A1-2 and step A1-3, the actual length from the starting node to the end node of the distribution line satisfies the following formula:

[0023]

[0024] Where: v a represents the speed of the fault traveling wave in the overhead line, v b Represents the speed of the fault traveling wave in the cable line;

[0025] Step C1-3: According to the results of step B1-2 and step B1-3, the parameters of each section from the starting node to the end node of the distribution line satisfy the following formula:

[0026]

[0027] Where: R L is a collection of branch line access nodes;

[0028] Step C1-4, jointly solve formula (1) and formula (2) established according to the disturbances at the ends of different distribution line branches to obtain the distribution line section parameters.

[0029] Step D: Once a fault occurs, the fault location is realized by using the arrival time of the traveling wave head recorded by the starting and ending nodes of the distribution line and the parameters of each section of the distribution line obtained in step C, as follows:

[0030] Step D1-1, record the fault transient traveling wave waveform obtained at the starting node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the starting node at the time t corresponding to the first mutation point 1,f ;

[0031] Step D1-2, record the fault transient traveling wave waveform obtained at the end node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the end node at the time t corresponding to the first mutation point 2,f ;

[0032] Step D1-3: locate the faulty traveling wave section of the distribution line. The faulty section k is determined by satisfying the following conditions. In actual application, the faulty section is searched and determined section by section:

[0033]

[0034] Step D1-4: Based on the determination of the fault section k, locate the fault location as the distance l from the starting node numbered i-1 of the fault section k. fk for:

[0035]

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention utilizes a controllable arc suppression coil at a substation grounding transformer or a power electronic device in a controllable capacitor compensator at a busbar and a power electronic device in a controllable capacitor compensator at a distribution transformer at the end of a branch line to generate a traveling wave waveform under active disturbance mode, and records the traveling wave waveforms at the starting and end nodes of the distribution line to determine the actual parameters of each section of the distribution line, thereby realizing high-precision traveling wave positioning of distribution line faults, and avoiding the influence of distribution line parameter loss or error on fault positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flow chart of a method for locating traveling wave faults in an active distribution network under disturbance of a power electronic device provided by an embodiment of the present invention;

[0039] Figure 2 The figure is a typical power distribution line topology diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] See also Figure 1 and Figure 2 The embodiment of the present invention provides an active distribution network traveling wave fault location method under power electronic device disturbance, comprising the following steps:

[0042] Step A, using a controllable arc suppression coil at a substation grounding transformer or a power electronic device in a controllable capacitor compensator at a busbar to generate a traveling wave waveform under active disturbance mode, and recording the traveling wave waveform at the starting end node and the end node of the distribution line;

[0043] Step B, using the power electronic device in the controllable capacitor compensator at the distribution transformer at the end of the branch line to generate a traveling wave waveform under active disturbance mode, and recording the traveling wave waveform at the starting end node and the end node of the distribution line;

[0044] Step C: based on the traveling wave waveforms at the starting and ending nodes of the distribution line obtained in steps A and B, extract the arrival time of the traveling wave head and calculate the parameters of each section of the distribution line.

[0045] Step D: Once a fault occurs, the fault location is achieved through the arrival time of the traveling wave head recorded by the starting and ending nodes of the distribution line, and the parameters of each section of the distribution line obtained in step C.

[0046] In step A, the controllable arc suppression coil at the grounding transformer of the substation or the power electronic device in the controllable capacitor compensator at the busbar is used to generate a traveling wave waveform under active disturbance mode, and the traveling wave waveforms at the starting end node and the end node of the distribution line are recorded, as follows:

[0047] Step A1-1, adjusting the controllable arc suppression coil at the substation grounding transformer or the electronic device in the controllable capacitor compensator at the busbar to change the equivalent reactance at the substation.

[0048] Step A1-2, record the traveling wave waveform of the starting node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the starting node at the first mutation point time t 1,1 .

[0049] Step A1-3, record the traveling wave waveform of the terminal node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the terminal node at the first mutation point time t 2,1 .

[0050] Step B: using the power electronic device in the controllable capacitor compensator at the distribution transformer at the end of the branch line to generate a traveling wave waveform under active disturbance mode, and recording the traveling wave waveform at the starting end node and the end node of the distribution line, as follows;

[0051] Step B1-1: Use branch line P m The power electronic device in the controllable capacitor compensator at the terminal distribution transformer changes the equivalent reactance at the substation at the end of the branch line. m It is a branch line connected to node m on the line from the starting node to the terminal node of the distribution line.

[0052] Step B1-2, record the traveling wave waveform of the starting node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the starting node at the time corresponding to the first mutation point

[0053] Step B1-3, record the traveling wave waveform of the terminal node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the terminal node at the time corresponding to the first mutation point

[0054] Step B1-4, repeat B1-1 to B1-3 until the moment when the traveling waves generated by the disturbance at the end of all branch lines reach the starting end node and the end node of the distribution line is obtained.

[0055] Step C: According to the traveling wave waveforms at the starting and ending nodes of the distribution line obtained in step A and step B, the arrival time of the traveling wave head is extracted, and the parameters of each section of the distribution line are calculated, as follows:

[0056] Step C1-1: Divide the distribution line into sections according to branch nodes, overhead-cable connection points, etc., from the starting node to the end node of the distribution line, and divide it into n sections. The length of the i-th section is l i , of type x i , x i =0 represents overhead line, x i =1 represents a cable line, the starting node of the i-th section is numbered i-1, and its end node is i.

[0057] Step C1-2: According to the results of step A1-2 and step A1-3, the actual length from the starting node to the end node of the distribution line satisfies the following formula:

[0058]

[0059] Where: v a represents the speed of the fault traveling wave in the overhead line, v b Represents the speed of the fault traveling wave in the cable line.

[0060] Step C1-3: According to the results of step B1-2 and step B1-3, the parameters of each section from the starting node to the end node of the distribution line satisfy the following formula:

[0061]

[0062] Where: R L It is the collection of branch line access nodes.

[0063] Step C1-4, jointly solve formula (1) and formula (2) established according to the disturbances at the ends of different distribution line branches, and solve to obtain the length parameters of the cables and overhead lines in the distribution line section.

[0064] Step D: Once a fault occurs, the fault location is achieved through the arrival time of the traveling wave head recorded by the starting and ending nodes of the distribution line, and the length parameters of the cables and overhead lines in each section of the distribution line obtained in step C, as follows:

[0065] Step D1-1, record the fault transient traveling wave waveform obtained at the starting node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the starting node at the time t corresponding to the first mutation point 1,f .

[0066] Step D1-2, record the fault transient traveling wave waveform obtained at the end node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the end node at the time t corresponding to the first mutation point 2,f .

[0067] Step D1-3: locate the faulty traveling wave section of the distribution line. The faulty section k is determined by satisfying the following conditions. In practical applications, it can be searched and determined section by section:

[0068]

[0069] Step D1-4: Based on the determination of the fault section k, locate the fault location as the distance l from the starting node numbered i-1 of the fault section k. fk for:

[0070]

[0071] The following is a specific example:

[0072] Active distribution network traveling wave fault location method under power electronic device disturbance, according to Figure 1 The steps given are to troubleshoot, Figure 2 A typical distribution line topology diagram is given.

[0073] (1) Figure 2 A disturbance signal is applied to the substation of the distribution network shown in the figure, and the traveling wave waveforms of the starting node 0 and the terminal node 3 of the distribution line are recorded, and the arrival time t of the traveling wave at the starting node 0 is obtained. 1,1 = 15 hours, 1 minute, 30 seconds, 45 microseconds, and the arrival time of the traveling wave at the end node 3 is t 2,1 =15 hours, 1 minute, 30 seconds, 166.8 microseconds.

[0074] (2) Figure 2 A disturbance signal is applied at the end of the branch line P1 of the distribution network shown in the figure, and the traveling wave waveforms of the starting node 0 and the end node 3 of the distribution line are recorded to obtain the arrival time of the traveling wave at the starting node 0. Get the arrival time of the traveling wave at the end node 3

[0075] (3) Figure 2 A disturbance signal is applied at the end of the P2 branch line of the distribution network shown in the figure, and the traveling wave waveforms of the starting node 0 and the end node 3 of the distribution line are recorded to obtain the arrival time of the traveling wave at the starting node 0. Get the arrival time of the traveling wave at the end node 3

[0076] (4) The distribution line section 1 is an overhead line, x1 = 0; section 2 is a cable line, x2 = 1; section 3 is an overhead line, x3 = 0; the speed of the traveling wave of the overhead line is v a =2.95·10 8 m / s, cable line traveling wave velocity v b =2.9·10 8 m / s. According to the arrival time of the traveling wave waveform obtained under the above active disturbance formula at the starting node and the end node of the distribution line, the following formula can be obtained:

[0077]

[0078]

[0079]

[0080] Combining the above formulas, we can calculate that the length of the overhead line in section 1 is l1 = 15.6 km, the length of the cable line in section 2 is l2 = 8.5 km, and the length of the overhead line in section 3 is l3 = 11.7 km. Figure 2 The distribution line parameters given above are subject to error.

[0081] (5) After a fault occurs, the arrival time of the fault traveling wave at the starting node of the distribution line is t 1,f = 16 hours, 9 minutes, 80 seconds, 80.9 microseconds. The arrival time of the fault wave at the end node of the distribution line is t 2,f = 16 hours, 9 minutes, 80 seconds, 67.3 microseconds. Based on this, the fault section k = 2, and the distance between the fault location and the end point 1 of section 2 is l fk =4.3km.

[0082] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An active distribution network traveling wave fault location method under power electronic device disturbance, characterized in that The following steps are involved: Step A, using a controllable arc suppression coil at a substation grounding transformer or a power electronic device in a controllable capacitor compensator at a busbar to generate a traveling wave waveform under active disturbance mode, and recording the traveling wave waveform at the starting end node and the end node of the distribution line; Step B, using the power electronic device in the controllable capacitor compensator at the distribution transformer at the end of the branch line to generate a traveling wave waveform under active disturbance mode, and recording the traveling wave waveform at the starting end node and the end node of the distribution line; Step C, extracting the arrival time of the traveling wave head according to the traveling wave waveforms at the starting node and the end node of the distribution line obtained in step A and step B, and calculating the parameters of each section of the distribution line; Step D: Once a fault occurs, the fault location is achieved through the arrival time of the traveling wave head recorded by the starting and ending nodes of the distribution line, and the parameters of each section of the distribution line obtained in step C; Step D specifically includes: Step D1-1, record the fault transient traveling wave waveform obtained at the starting node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the starting node traveling wave waveform at the first mutation point corresponding to the time t 1,f ; Step D1-2, record the fault transient traveling wave waveform obtained at the end node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the end node at the time t corresponding to the first mutation point 2,f ; Step D1-3: locate the faulty traveling wave section of the distribution line. The faulty section k is determined by satisfying the following conditions. In practical applications, it can be searched and determined section by section: Step D1-4: Based on the determination of the fault section k, locate the fault location as the distance l from the starting node numbered i-1 of the fault section k. fk for:

2. The method for locating traveling wave faults in an active distribution network under disturbance of a power electronic device according to claim 1, characterized in that: In step A, the controllable arc suppression coil at the grounding transformer of the substation or the power electronic device in the controllable capacitor compensator at the busbar is used to generate a traveling wave waveform under active disturbance mode, and the traveling wave waveforms at the starting end node and the end node of the distribution line are recorded, as follows: Step A1-1, adjusting the electronic device in the controllable arc suppression coil at the grounding transformer of the substation or the controllable capacitor compensator at the busbar to change the equivalent reactance at the substation; Step A1-2, record the traveling wave waveform of the starting node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the starting node at the first mutation point time t 1,1 ; Step A1-3, record the traveling wave waveform of the terminal node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the terminal node at the first mutation point time t 2,1 .

3. The method for locating traveling wave faults in an active distribution network under disturbance of a power electronic device according to claim 2, characterized in that: Step B: using the power electronic device in the controllable capacitor compensator at the distribution transformer at the end of the branch line to generate a traveling wave waveform under active disturbance mode, and recording the traveling wave waveform at the starting end node and the end node of the distribution line, as follows; Step B1-1: Use branch line P m The power electronic device in the controllable capacitor compensator at the terminal distribution transformer changes the equivalent reactance at the substation at the end of the branch line. m A branch line connected to a node m on the line from the starting node to the terminal node of the distribution line; Step B1-2, record the traveling wave waveform of the starting node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the starting node at the time corresponding to the first mutation point Step B1-3, record the traveling wave waveform of the terminal node of the distribution line, perform differential derivative on the traveling wave waveform, and use the maximum value of the derivative to obtain the traveling wave waveform of the terminal node at the time corresponding to the first mutation point Step B1-4, repeat B1-1 to B1-3 until the moment when the traveling waves generated by the disturbance at the end of all branch lines reach the starting end node and the end node of the distribution line is obtained.

4. The method for locating traveling wave faults in an active distribution network under disturbance of a power electronic device according to claim 3, characterized in that: In step C, according to the traveling wave waveforms at the starting and ending nodes of the distribution line obtained in steps A and B, the arrival time of the traveling wave head is extracted, and the parameters of each section of the distribution line are calculated, which are specifically as follows: Step C1-1: Divide the distribution line into sections according to branch nodes and overhead-cable connection points. From the starting node to the end node of the distribution line, it is divided into n sections, and the length of the i-th section is l i , of type x i , x i =0 represents overhead line, x i =1 represents a cable line, the starting node of the i-th section is numbered i-1, and its end node is i; Step C1-2: According to the results of step A1-2 and step A1-3, the actual length from the starting node to the end node of the distribution line satisfies the following formula: Where: v a represents the speed of the fault traveling wave in the overhead line, v b represents the speed of the fault traveling wave in the cable line, t 1,1 represents the time when the active disturbance downlink wave of the substation reaches the starting node of the distribution line, t 1,1 Represents the time when the active disturbance downlink wave of the substation reaches the terminal node of the distribution line; Step C1-3: According to the results of step B1-2 and step B1-3, the parameters of each section from the starting node to the end node of the distribution line satisfy the following formula: Where: R L is the set of branch line access nodes, Represents the branch line P connected to node m m The moment when the terminal active disturbance downward wave reaches the starting node of the distribution line, Represents the branch line P connected to node m m The moment when the terminal active disturbance downward wave reaches the terminal node of the distribution line; Step C1-4, jointly solve formula (1) and formula (2) established according to the disturbances at the ends of different distribution line branches to obtain the distribution line section parameters.

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