A method and system for tracing source of distribution network line faults

Abstract

The invention relates to the technical field of distribution network, and specifically discloses a distribution network line fault tracing method and system, comprising the following steps: obtaining a voltage fluctuation degree at a main line end in a distribution network line based on three-phase voltage calculation to obtain a phase voltage fault analysis signal; calculating and obtaining a zero-sequence current change rate at time t; obtaining a fault troubleshooting signal; and then obtaining a power grid fault signal based on a negative-sequence current value; acquiring main line impedance data at a main line end, calculating and obtaining a main line fault point distance value and a branch voltage value, dividing the branch into sub-areas, and calculating a voltage deviation abnormality rate of each sub-area in the branch; comparing the voltage deviation abnormality rate with a voltage deviation abnormality rate threshold; obtaining a sub-area voltage abnormality signal; determining an abnormal line in the distribution network, improving the ability to analyze the cause of the fault, realizing the detection of multiple faults, and at the same time determining the precise position of the fault point in the branch, facilitating further maintenance and improving maintenance efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network, and in particular to a method and system for tracing the source of a distribution network line fault. Background Art

[0002] As the transmission unit of electric energy, the distribution network plays a vital role in the power grid. Its structure type is mostly radial and closely connected with the user side. With the rapid economic development, the demand for electricity is increasing, resulting in the expansion of the scale of the distribution network and the gradual increase in the failure rate. Based on this, the system is required to effectively locate the fault section in real time so that the staff can troubleshoot the fault as soon as possible, thereby reducing economic losses.

[0003] At present, the identification of fault sections in distribution networks is mainly based on current information. With the widespread application of feeder automation terminals, the fault section location method based on current information is direct in principle and easy to implement. So far, direct algorithms based on matrix analysis theory and indirect methods using artificial intelligence technology have been formed. Existing matrix algorithms are divided into the following two categories: one is based on the network base structure, and the other is based on the network shape structure;

[0004] However, in the process of transmitting three-phase voltage between the main line and the branch line, and in the process of analyzing the power grid fault, the above scheme cannot determine the abnormal fault problem based on different operating states. At the same time, when facing the abnormal operation of the branch line, the reaction time is long and the location of the fault point cannot be accurately calculated. Summary of the invention

[0005] The object of the present invention is to provide a method and system for tracing the source of a distribution network line fault, so as to solve the above-mentioned problems.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A method for tracing a fault in a power distribution network comprises the following steps:

[0008] Obtain the three-phase voltage of the main terminal voltage in the distribution network line at time t, and calculate the voltage fluctuation Uflut of the main terminal in the distribution network line based on the three-phase voltage;

[0009] Compare the voltage fluctuation Uflut at the main line with the preset value Upre; obtain the phase voltage fault analysis signal; calculate and obtain the zero-sequence current change rate VLi at time t t ; and the zero-sequence current change rate VLi t Compare with the ground fault change rate VLigz to obtain a fault troubleshooting signal;

[0010] Get the negative sequence current value FLi at time t t and the negative sequence current value FLi at the previous moment t-1t-1 ; The negative sequence current value FLi at time t t and the negative sequence current value FLi at time t-1 t-1 Make comparisons; obtain power grid fault signals;

[0011] Based on the power grid fault signal, the main line impedance data of the main line end is obtained, the main line fault point distance value DL and the branch voltage value ZU are calculated, and each branch connected to the main line is marked as i in sequence, i is 1, 2, 3..., and the distance value JD from the main line fault point to the branch and the main line connection point is obtained i The branch number i corresponding to the minimum value in ;

[0012] Based on the branch voltage value ZU, the branch is divided into sub-areas, and the sub-areas under the branch are marked as j; j is 1, 2, 3...; the voltage deviation abnormality rate Cub of each sub-area in the branch is calculated j ;

[0013] The voltage deviation abnormality rate Cub j Compare with voltage deviation abnormality rate threshold Cuby;

[0014] If the voltage deviation abnormality rate Cub j If it is less than or equal to the voltage deviation abnormal rate threshold Cuby, a sub-region voltage stability signal is generated;

[0015] If the voltage deviation abnormality rate Cub j If it is greater than the voltage deviation abnormal rate threshold Cuby, a sub-area voltage abnormality signal is generated; the abnormal line in the distribution network is determined to be the voltage abnormality in sub-area j in branch i.

[0016] As a further solution of the present invention: the three-phase voltages are marked as XUmax, XUmid and XUmin respectively; wherein XUmax is the maximum value of the three-phase voltages, XUmid is the middle value of the three-phase voltages, and XUmin is the minimum value of the three-phase voltages; by The voltage fluctuation Uflut of the main terminal voltage in the distribution network is calculated.

[0017] As a further solution of the present invention: when the voltage fluctuation degree Uflut of a plurality of road terminals is less than or equal to the preset fluctuation value Upre, a circuit network voltage stability signal is generated;

[0018] When the voltage fluctuation Uflut at some terminals is greater than the preset fluctuation value Upre, a phase voltage fault analysis signal is generated.

[0019] As a further solution of the present invention: the zero-sequence current change rate VLi at time t is t The calculation method is:

[0020] The zero-sequence current value at time t is obtained through the zero-sequence current transformer and marked as LI t At the same time, the zero-sequence current value at the monitoring time point t-1 before time t is obtained and marked as LI t-1 ;

[0021] pass Calculate the zero-sequence current change rate VLi at time t t .

[0022] As a further solution of the present invention: if the zero-sequence current change rate VLi t Greater than or equal to the ground fault change rate VLigz; a low-voltage ground fault signal is generated, and a ground fault occurs in the line with a phase voltage of XUmin;

[0023] If the zero-sequence current change rate VLi t It is smaller than the ground fault change rate VLigz, and a fault troubleshooting signal is generated.

[0024] As a further solution of the present invention: the negative sequence current value FLi at time t is t and the negative sequence current value FLi at time t-1 t-1 Make comparisons;

[0025] If the negative sequence current value FLi at time t t Greater than the negative sequence current value FLi at time t-1 t-1 ; Generate a power grid fault signal;

[0026] Otherwise, a phase fault signal is generated.

[0027] As a further solution of the present invention: based on the phase fault signal, the phase wires of the three-phase voltage are marked, wherein the phase line corresponding to the maximum voltage XUmax in the three-phase voltage is marked as the A-phase wire, the phase line corresponding to the intermediate voltage XUmid is marked as the B-phase wire, and the phase line corresponding to the minimum voltage XUmin is marked as the C-phase wire;

[0028] Get the current values ​​of phase A, phase B, and phase C in the three-phase line at time t, and mark them as IA t , IB t and IC t， And obtain the current value stable value Ista; it should be noted that the current value stable value is the theoretical stable current value in the three-phase line;

[0029] pass Calculate and obtain the current fluctuation ratio IAflu of the A-phase wire;

[0030] Calculate and obtain the current fluctuation ratios IBflu and ICflu of the B-phase wire and the C-phase wire respectively;

[0031] Determine whether the current fluctuation ratio of the three-phase wire is within the safe fluctuation range [Iflu do , Iflu on ]Inside;

[0032] If the phase current fluctuation ratios IAflu, IBflu and ICflu in the three-phase power line are all in [Iflu do , Iflu on ], a normal phase connection signal is generated;

[0033] If the current fluctuation ratio of any phase in the three-phase wire is greater than the maximum safe fluctuation Iflu on , a phase-to-phase short-circuit signal is generated;

[0034] If the current fluctuation ratio of any phase in the three-phase wire is less than the minimum safe fluctuation value Iflu do , a phase-to-phase disconnection signal is generated.

[0035] As a further solution of the present invention: the trunk impedance data includes: a trunk resistance value GR, a trunk reactance value GX and a trunk length value GL;

[0036] The calculation method of the distance value DL of the trunk fault point is:

[0037] Obtain the impedance value of the trunk line through an impedance tester and mark it as Gzk;

[0038] Then pass Calculate and obtain the distance value DL of the main line fault point;

[0039] The branch voltage value ZU is calculated as follows:

[0040] Based on the minimum value XUmin of the three-phase voltage of the main line, the impedance value of the branch closest to the main line fault point is obtained and marked as ZX, and the main line impedance value Gzk is obtained at the same time;

[0041] pass The branch voltage value ZU of the branch i is obtained by calculation.

[0042] As a further solution of the present invention: the voltage deviation abnormality rate of the sub-region in the branch is calculated as follows:

[0043] Get the branch current value and mark it as ZI, and the sub-area voltage value QV of each sub-area j j And the sub-region resistance value R j ;

[0044] pass The theoretical voltage value of the sub-area is calculated and marked as LLU j ;

[0045] Theoretical voltage value LLU based on sub-area j ,pass Calculate voltage deviation CPU j ;

[0046] pass Calculate the sub-region voltage deviation mean CPUmean of the power grid under the branch;

[0047] Based on the sub-region voltage deviation mean CPUmean, Calculate the voltage deviation abnormality rate Cub of each sub-area in the branch sub-area j .

[0048] As a further solution of the present invention: a distribution network line fault tracing system, comprising:

[0049] Data acquisition module: used to obtain the three-phase voltage of the main terminal voltage in the distribution network line at time t, and calculate the voltage fluctuation Uflut of the main terminal voltage in the distribution network line based on the three-phase voltage;

[0050] Data processing module: used to compare the voltage fluctuation Uflut at the main circuit end with the preset fluctuation value Upre to obtain a phase voltage fault analysis signal;

[0051] Based on the phase voltage fault analysis signal, the zero-sequence current change rate VLi at time t is calculated t , and the zero-sequence current change rate VLi t Compare with the ground fault change rate VLigz to obtain a fault troubleshooting signal;

[0052] Signal troubleshooting module: Based on the fault troubleshooting signal, obtain the negative sequence current value FLi at time t t and the negative sequence current value FLi at the previous moment t-1 t-1 ; The negative sequence current value FLi at time t t and the negative sequence current value FLi at time t-1 t-1 Make comparisons; obtain power grid fault signals;

[0053] Fault location module: Based on the power grid fault signal, obtain the trunk impedance data at the trunk end, calculate the trunk fault point distance value DL and the branch voltage value ZU, mark each branch connected to the trunk as i in sequence, i is 1, 2, 3..., obtain the distance value JD from the trunk fault point to the branch and the trunk connection point i The branch number i corresponding to the minimum value in ;

[0054] Based on the branch voltage value ZU, the branch is divided into sub-areas, and the sub-areas under the branch are marked as j; j is 1, 2, 3...; the voltage deviation abnormality rate Cub of each sub-area in the branch is calculatedj ;

[0055] The voltage deviation abnormality rate Cub j Compare with voltage deviation abnormality rate threshold Cuby;

[0056] If the voltage deviation abnormality rate Cub j If it is less than or equal to the voltage deviation abnormal rate threshold Cuby, a sub-region voltage stability signal is generated;

[0057] If the voltage deviation abnormality rate Cub j If the voltage deviation is greater than the voltage deviation abnormal rate threshold Cuby, a sub-area voltage abnormality signal is generated; and the abnormal line in the distribution network is determined to be the voltage abnormality in sub-area j in branch i.

[0058] Beneficial effects of the present invention:

[0059] In the present invention, firstly, the zero-sequence current is analyzed based on the voltage fault analysis signal. When a ground fault occurs in the three-phase voltage, it will affect the abnormal change of the current. At this time, it will cause an abnormal increase in the zero-sequence current. Therefore, when the change rate of the zero-sequence current reaches the ground fault change rate, it indicates that a ground fault occurs in this state. At this time, the grounding of the distribution network trunk can be checked. It should be noted that since the zero-sequence current changes due to the abnormal voltage reduction, it can be preferentially detected whether the phase wire with the smallest voltage has a ground fault.

[0060] Then, different detection schemes are determined based on different fault types. When a fault occurs in the distribution network, the main fault point in the power grid is calculated based on the fault signal, and then the branch line closest to the fault point is analyzed; the branches in the distribution network are divided into sub-areas, and the voltage deviation in the sub-area is further calculated. When a large abnormal voltage deviation occurs, it means that a fault has occurred in the area and an abnormal signal is generated. At this time, the line fault point in the distribution network can be determined, and the fault in the distribution network can be repaired more accurately; the ability to analyze the cause of the fault is improved, and the detection of various faults is realized. At the same time, the precise location of the fault point in the branch can be determined, which is convenient for further maintenance and improves maintenance efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The present invention will be further described below in conjunction with the accompanying drawings.

[0062] Figure 1 It is a schematic flow chart of the method of the present invention;

[0063] Figure 2 It is a system block diagram of the present invention. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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. Embodiment 1

[0065] See also Figure 1 As shown, the present invention is a method for tracing the source of a distribution network line fault, comprising the following steps:

[0066] Step 01: Take the monitoring period T as a monitoring period, obtain the three-phase voltages in the main terminal voltage of the distribution network line at time t, mark them as X1, X2 and X3 respectively, and take the maximum value, middle value and minimum value of the three-phase voltage as XUmax, XUmid and XUmin respectively; among which XUmax is the maximum value of the three-phase voltage, XUmid is the middle value of the three-phase voltage, and XUmin is the minimum value of the three-phase voltage;

[0067] Based on the three-phase voltage, The voltage fluctuation Uflut at the trunk end of the distribution network is calculated;

[0068] Step 02: Compare the voltage fluctuation Uflut at the trunk terminal with the preset fluctuation value Upre;

[0069] If the voltage fluctuation degree Uflut at the trunk line end is less than or equal to the preset fluctuation value Upre, a circuit network voltage stability signal is generated, indicating that the current trunk line is normal and has no faults.

[0070] If the voltage fluctuation Uflut at the trunk line is greater than the preset fluctuation value Upre, a phase voltage fault analysis signal is generated; the phase voltage fault analysis signal indicates that the current trunk line has a fault or a risk of a fault.

[0071] Based on the voltage fluctuations between the three-phase voltages in the power grid, the analysis signal of the distribution network line fault is obtained. When there is a fault or fault risk in the main line, further circuit fault analysis is performed on the faulty main line in the distribution network to obtain more accurate abnormalities and fault problem points;

[0072] Step 03: Based on the phase voltage fault analysis signal, the zero-sequence current value at time t is obtained through the zero-sequence current transformer and marked as LI t At the same time, the zero-sequence current value at the monitoring time point t-1 before time t is obtained and marked as LI t-1 ;

[0073] pass Calculate the zero-sequence current change rate VLi at time t t ; and the zero-sequence current change rate VLi t Compare with the ground fault change rate VLigz;

[0074] If the zero-sequence current change rate VLi t If the voltage is greater than or equal to the ground fault change rate VLigz, a low-voltage ground fault signal is generated. At this time, a ground fault occurs in the line with a phase voltage of XUmin.

[0075] If the zero-sequence current change rate VLi t It is smaller than the ground fault change rate VLigz, generating a fault troubleshooting signal;

[0076] First, based on the voltage fault analysis signal, the zero-sequence current is analyzed. When a ground fault occurs in the three-phase voltage, it will affect the abnormal change of the current. At this time, it will cause an abnormal increase in the zero-sequence current. Therefore, when the change rate of the zero-sequence current reaches the ground fault change rate, it indicates that a ground fault occurs in this state. At this time, the grounding of the distribution network trunk can be checked. It should be noted that since the zero-sequence current changes due to the abnormal voltage reduction, it is possible to preferentially detect whether the phase wire with the smallest voltage has a ground fault.

[0077] Step 04: Based on the fault troubleshooting signal, obtain the negative sequence current value at time t through the negative sequence current transformer and mark it as FLi t At the same time, the negative sequence current value at the monitoring time point t-1 before time t is obtained and marked as FLi t-1 ;

[0078] Then the negative sequence current value FLi at time t is t and the negative sequence current value FLi at time t-1 t-1 Make comparisons;

[0079] If the negative sequence current value FLi at time t t Greater than the negative sequence current value FLi at time t-1 t-1 ; Generate a power grid fault signal; Execute step 06;

[0080] Otherwise, a phase fault signal is generated; step 05 is executed; it should be noted that when a phase voltage in the three-phase voltage is abnormal, the current in the phase wire will also change. When the current in the phase wire changes abnormally, it is necessary to further confirm whether there is a short circuit or a circuit break in the three-phase line;

[0081] Therefore, it is necessary to monitor the phase current in the three-phase line to determine whether there is a short circuit or open circuit;

[0082] Step 05: Based on the phase fault signal, the phase wires of the three-phase voltage are marked, wherein the phase line corresponding to the maximum voltage XUmax in the three-phase voltage is marked as the A-phase wire, the phase line corresponding to the intermediate voltage XUmid is marked as the B-phase wire, and the phase line corresponding to the minimum voltage XUmin is marked as the C-phase wire;

[0083] Get the current values ​​of phase A, phase B and phase C in the three-phase line at the monitoring time point t, and mark them as IA respectively t , IB t and IC t, , and obtain the current value stable value Ista; the current value stable value is the rated value during the operation of the three-phase line;

[0084] pass Calculate and obtain the current fluctuation ratio IAflu of the A-phase wire;

[0085] pass Calculate and obtain the current fluctuation ratio IBflu of the B-phase wire;

[0086] pass Calculate and obtain the current fluctuation ratio ICflu of the C phase wire;

[0087] Determine whether the current fluctuation ratio of the three-phase line is within the safe fluctuation range [Iflu do , Iflu on It should be noted that when there is a short circuit or open circuit in the phase circuit, the current fluctuation may increase or decrease. When the phase circuit current increases, the current fluctuation ratio is greater than zero. Therefore, the maximum safe fluctuation Iflu on It should be a preset value greater than 0; when the phase circuit current decreases, the current fluctuation ratio is less than zero, and when the current decreases to zero, the maximum current fluctuation ratio of the phase circuit is -1. Therefore, the minimum safe fluctuation value Iflu do It should be greater than -1 and less than 0; at this time, the current fluctuation ratio in the three-phase line is judged;

[0088] If the current fluctuation ratios of the three-phase line IAflu, IBflu and ICflu are all in [Iflu do , Iflu on ], a normal phase connection signal is generated;

[0089] If the current fluctuation ratio of any phase line is greater than the maximum safe fluctuation value Iflu on , a short-circuit signal between phases is generated; it should be noted that during operation, a short circuit between phases may occur between two phases or three phases, which will cause an increase in the current of the phase wires. At this time, a short-circuit detection of the three-phase wires is required;

[0090] If the current fluctuation ratio of any phase line is less than the minimum safe fluctuation value Iflu do , then a phase-to-phase circuit break signal is generated; during the circuit operation process, when a phase line is broken, the current in the broken phase circuit will decrease or become 0. At this time, it is necessary to detect the abnormal phase circuit;

[0091] It should be noted that short circuit and open circuit are different in nature in three-phase circuits, and the two mixed faults will not occur in three-phase circuits. Mixed faults in three-phase circuits are not considered.

[0092] Step 06: Based on the power grid fault signal, obtain the trunk impedance data of the trunk end, wherein the trunk impedance data includes: trunk resistance value, trunk reactance value and trunk length value (i.e., trunk total length value);

[0093] The trunk resistance value is marked as GR, the trunk reactance value is marked as GX, and the trunk length value is marked as GL;

[0094] Obtain the impedance value of the trunk line through an impedance tester and mark it as Gzk;

[0095] Then pass Calculate and obtain the distance value DL of the main line fault point;

[0096] Based on the distance value DL of the main road fault point, the main road fault point is located to determine the branch road closest to the main road fault point;

[0097] Specifically, the branches connected to the trunk in the distribution network are numbered and marked as i, where i is 1, 2, 3, etc. At the same time, the distance value between each branch and the trunk connection point and the trunk measurement endpoint is obtained and marked as ZD i ;

[0098] pass Calculate the distance JD between the main road fault point and the branch road connection point i ; Get the distance JD between the main road fault point and the branch and main road connection point i The branch number i corresponding to the minimum value in ;

[0099] Then, the minimum value XUmin of the three-phase voltage of the main line is obtained, and the impedance value of the branch closest to the main line fault point is obtained and marked as ZX, and the main line impedance value Gzk is obtained at the same time;

[0100] pass Calculate and obtain the branch voltage value ZU of the branch i;

[0101] Based on the branch voltage value ZU, the power grid under the branch is divided into sub-areas, and the sub-areas under the branch are marked as j; where j is 1, 2, 3, ...;

[0102] The branch current value is obtained through the current sensor and marked as ZI; the sub-region voltage value of each sub-region j is obtained through the voltage sensor and marked as QV j ; At the same time, obtain the resistance value of each sub-area under the branch and mark it as R j ;

[0103] pass The theoretical voltage value of the sub-area is calculated and marked as LLU j ;

[0104] Theoretical voltage value LLU based on sub-area j ,pass Calculate voltage deviation CPU j ;

[0105] pass Calculate the sub-region voltage deviation mean CPUmean of the power grid under the branch;

[0106] Based on the sub-region voltage deviation mean CPUmean, Calculate the voltage deviation abnormality rate Cub of each sub-area in the branch sub-area j ;

[0107] The voltage deviation abnormality rate Cub j Compare with voltage deviation abnormality rate threshold Cuby;

[0108] If the voltage deviation abnormality rate Cub j When the voltage deviation abnormality rate is less than or equal to the voltage deviation abnormality rate threshold Cuby, a sub-region voltage stability signal is generated;

[0109] If the voltage deviation abnormality rate Cub j When it is greater than the voltage deviation abnormal rate threshold Cuby, a sub-region voltage abnormality signal is generated;

[0110] It should be noted that since the input voltage in the power grid branch, i.e., the branch voltage, is the same, and the branch current is also the same, therefore, in the calculation process, as long as the voltage deviation of each branch is calculated, it can be obtained that a certain branch sub-area has a fault;

[0111] At this time, it can be determined that the abnormal line in the distribution network is the abnormal voltage in sub-area j of branch i; then the fault can be repaired;

[0112] It should be noted that if the sub-areas of the power grid under the branch all generate sub-area voltage stability signals, then the next branch is detected, and the next branch may be the next branch closest to the fault point;

[0113] First, a fault analysis is performed on the type of main line fault in the power grid, and then different detection schemes are determined based on different fault types. When a fault occurs in the distribution network, the main line fault point in the power grid is calculated based on the fault signal, and then the branch line closest to the fault point is analyzed; the branch in the distribution network is then divided into sub-areas, and the voltage deviation in the sub-area can be further calculated. When a large abnormal voltage deviation occurs, it means that a fault has occurred in the area and an abnormal signal is generated. At this time, the line fault point in the distribution network can be determined, and the fault in the distribution network can be repaired more accurately; the ability to analyze the cause of the fault is improved, and the detection of multiple faults is realized. At the same time, the precise location of the fault point in the branch can be determined, which is convenient for further maintenance and improves maintenance efficiency. Embodiment 2

[0114] Reference Figure 2 As shown, a distribution network line fault tracing system includes:

[0115] Data acquisition module: used to obtain the three-phase voltage of the main terminal voltage in the distribution network line at time t, and calculate the voltage fluctuation Uflut of the main terminal voltage in the distribution network line based on the three-phase voltage;

[0116] Data processing module: used to compare the voltage fluctuation Uflut at the main circuit end with the preset fluctuation value Upre to obtain a phase voltage fault analysis signal;

[0117] Based on the phase voltage fault analysis signal, the zero-sequence current change rate VLi at time t is calculated t , and the zero-sequence current change rate VLi t Compare with the ground fault change rate VLigz to obtain a fault troubleshooting signal;

[0118] Signal troubleshooting module: Based on the fault troubleshooting signal, obtain the negative sequence current value FLi at time t t and the negative sequence current value FLi at the previous moment t-1 t-1 ; The negative sequence current value FLi at time t t and the negative sequence current value FLi at time t-1 t-1 Make comparisons; obtain power grid fault signals;

[0119] Fault location module: Based on the power grid fault signal, obtain the trunk impedance data at the trunk end, calculate the trunk fault point distance value DL and the branch voltage value ZU, mark each branch connected to the trunk as i in sequence, i is 1, 2, 3..., obtain the distance value JD from the trunk fault point to the branch and the trunk connection point i The branch number i corresponding to the minimum value in ;

[0120] Based on the branch voltage value ZU, the branch is divided into sub-areas, and the sub-areas under the branch are marked as j; j is 1, 2, 3...; the voltage deviation abnormality rate Cub of each sub-area in the branch is calculated j ;

[0121] The voltage deviation abnormality rate Cub j Compare with voltage deviation abnormality rate threshold Cuby;

[0122] If the voltage deviation abnormality rate Cub j If it is less than or equal to the voltage deviation abnormal rate threshold Cuby, a sub-region voltage stability signal is generated;

[0123] If the voltage deviation abnormality rate Cub j If the voltage deviation is greater than the voltage deviation abnormal rate threshold Cuby, a sub-area voltage abnormality signal is generated; and the abnormal line in the distribution network is determined to be the voltage abnormality in sub-area j in branch i.

[0124] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for tracing the source of a distribution network line fault, characterized in that: The following steps are involved: Obtain the three-phase voltage of the main terminal voltage in the distribution network line at the monitoring time point t, and calculate the voltage fluctuation Uflut of the main terminal in the distribution network line based on the three-phase voltage; Then compare the voltage fluctuation Uflut at the trunk end with the preset fluctuation value Upre; Obtaining phase voltage fault analysis signal; Calculate the zero-sequence current change rate VLi at the monitoring time point t t ; and the zero-sequence current change rate VLi t Compare with the ground fault change rate VLigz to obtain a fault troubleshooting signal; Based on the fault troubleshooting signal, obtain the negative sequence current value FLi at the monitoring time point t t and the negative sequence current value FLi at the previous monitoring time point t-1 t-1 ; Monitor the negative sequence current value FLi at time point t t The negative sequence current value FLi at the monitoring time point t-1 t-1 Make comparisons; obtain power grid fault signals; Based on the power grid fault signal, the main line impedance data of the main line end is obtained, the main line fault point distance value DL and the branch voltage value ZU are calculated, and the branches connected to the main line are marked as i in sequence, i is 1, 2, 3..., and the distance value JD from the main line fault point to the branch and the main line connection point is obtained i The branch number i corresponding to the minimum value in ; The trunk impedance data includes: trunk resistance value GR, trunk reactance value GX and trunk length value GL; The calculation method of the distance value DL of the trunk fault point is: Obtain the impedance value of the trunk line through an impedance tester and mark it as Gzk; Then pass Calculate and obtain the distance value DL of the main line fault point; The branch voltage value ZU is calculated as follows: Based on the minimum value XUmin of the three-phase voltage of the main line, the impedance value of the branch closest to the main line fault point is obtained and marked as ZX, and the main line impedance value Gzk is obtained at the same time; pass Calculate and obtain the branch voltage value ZU of branch i; Then, based on the branch voltage value ZU, the branch is divided into sub-areas, and the sub-areas under the branch are marked as j; j is 1, 2, 3, etc.; the voltage deviation abnormality rate Cub of each sub-area in the branch is calculated j ; The calculation method of the voltage deviation abnormality rate of the sub-area in the branch is: Get the branch current value and mark it as ZI and the sub-area voltage value QV of each sub-area j j And the sub-region resistance value R j ; pass The theoretical voltage value of the sub-area is calculated and marked as LLU j ; Theoretical voltage value LLU based on sub-area j ,pass Calculate voltage deviation CPU j ; pass Calculate the sub-region voltage deviation mean CPUmean of the power grid under the branch; Based on the sub-region voltage deviation mean CPUmean; Calculate the voltage deviation abnormality rate Cub of each sub-area in the branch sub-area j ; The voltage deviation abnormality rate Cub j Compare with the voltage deviation abnormal threshold Cuby; If the voltage deviation abnormality rate Cub j Less than or equal to the voltage deviation abnormal threshold Cuby; generating a sub-region voltage stability signal; If the voltage deviation abnormality rate Cub j Greater than the voltage deviation abnormal threshold Cuby; generating a sub-area voltage abnormality signal; determining the abnormal line in the distribution network as the voltage abnormality in sub-area j in branch i.

2. A method for tracing the source of a distribution network line fault according to claim 1, characterized in that: The three-phase voltages are marked as XUmax, XUmid and XUmin respectively; wherein XUmax is the maximum value of the three-phase voltages, XUmid is the middle value of the three-phase voltages, and XUmin is the minimum value of the three-phase voltages; pass The voltage fluctuation Uflut at the trunk end of the distribution network is calculated.

3. A method for tracing the source of a distribution network line fault according to claim 1, characterized in that: When comparing the voltage fluctuation Uflut at the trunk terminal with the preset fluctuation value Upre; When the voltage fluctuation Uflut of several road terminals is less than or equal to the fluctuation safety value Upre, a circuit network voltage stability signal is generated; When the voltage fluctuation Uflut at some terminals is greater than the fluctuation safety value Upre, a phase voltage fault analysis signal is generated.

4. A method for tracing the source of a distribution network line fault according to claim 1, characterized in that: The zero-sequence current change rate VLi at the monitoring time point t t The calculation method is: The zero-sequence current value at the monitoring time point t is obtained through the zero-sequence current transformer and marked as LI t At the same time, the zero-sequence current value at the monitoring time point t-1 of the monitoring cycle T before the monitoring time point t is obtained and marked as LI t-1 ; pass Calculate the zero-sequence current change rate VLi at the monitoring time point t t .

5. A method for tracing the source of a distribution network line fault according to claim 1 or 4, characterized in that: The zero-sequence current change rate VLi t When compared with the ground fault change rate VLigz, if the zero-sequence current change rate VLi t Greater than or equal to the ground fault change rate VLigz; a low voltage ground fault signal is generated; that is, a ground fault occurs in the line with a phase voltage of XUmin; If the zero-sequence current change rate VLi t Less than the ground fault change rate VLigz; Generates troubleshooting signals.

6. A method for tracing the source of a distribution network line fault according to claim 1, characterized in that: The negative sequence current value FLi at the monitoring time point t t The negative sequence current value FLi at the monitoring time point t-1 t-1 Make comparisons; If the negative sequence current value FLi at the monitoring time point t t Greater than the negative sequence current value FLi at the monitoring time point t-1 t-1 ; Generate a power grid fault signal; Otherwise, a phase fault signal is generated.

7. A method for tracing the source of a distribution network line fault according to claim 6, characterized in that: If a phase fault signal is generated, the phase wires of the three-phase voltage are marked, wherein the phase line corresponding to the maximum voltage XUmax in the three-phase voltage is marked as the A phase wire, the phase line corresponding to the intermediate voltage XUmid is marked as the B phase wire, and the phase line corresponding to the minimum voltage XUmin is marked as the C phase wire; Get the current values ​​of phase A, phase B and phase C in the three-phase line at the monitoring time point t, and mark them as IA respectively t , IB t and IC t ; pass The current fluctuation ratio IAflu of the A-phase electric wire is calculated; wherein Ista is the stable value of the current value; Then calculate and obtain the current fluctuation ratios IBflu and ICflu of the B-phase wire and the C-phase wire respectively; Determine whether the current fluctuation ratio of the three-phase power line is within the safe fluctuation range [Iflu do , Iflu on ]Inside; If the current fluctuation ratios of the three-phase wires IAflu, IBflu and ICflu are all within the range of [Iflu do , Iflu on ], a normal phase connection signal is generated; If the current fluctuation ratio of any phase in the three-phase wire is greater than the maximum safe fluctuation Iflu on , a phase-to-phase short-circuit signal is generated; If the current fluctuation ratio of any phase in the three-phase wire is less than the minimum safe fluctuation value Iflu do , a phase-to-phase disconnection signal is generated.

8. A distribution network line fault tracing system, characterized in that: The system is used to execute the distribution network line fault tracing method as described in any one of claims 1 to 7 above, comprising: Data acquisition module: used to obtain the three-phase voltage in the main terminal voltage of the distribution network line at the monitoring time point t, and calculate the voltage fluctuation Uflut of the main terminal of the distribution network line based on the three-phase voltage; Data processing module: used to compare the voltage fluctuation Uflut at the main circuit end with the preset value Upre; obtain the phase voltage fault analysis signal; calculate the zero-sequence current change rate VLi at the monitoring time point t t ; and the zero-sequence current change rate VLi t Compare with the ground fault change rate VLigz to obtain a fault troubleshooting signal; Signal troubleshooting module: Based on the fault troubleshooting signal, obtain the negative sequence current value FLi at the monitoring time point t t and the negative sequence current value FLi at the previous monitoring time point t-1 t-1 ; Monitor the negative sequence current value FLi at time point t t The negative sequence current value FLi at the monitoring time point t-1 t-1 Make comparisons; obtain power grid fault signals; Fault location module: Based on the power grid fault signal, obtain the trunk impedance data at the trunk end, calculate the trunk fault point distance value DL and the branch voltage value ZU, mark the branches connected to the trunk as i in sequence, i is 1, 2, 3..., and obtain the distance value JD from the trunk fault point to the branch and the trunk connection point i The branch number i corresponding to the minimum value in ; Based on the branch voltage value ZU, the branch is divided into sub-areas, and the sub-areas under the branch are marked as j; j is 1, 2, 3...; the voltage deviation abnormality rate Cub of each sub-area in the branch is calculated j ; The voltage deviation abnormality rate Cub j Compare with the voltage deviation abnormal threshold Cuby; If the voltage deviation abnormality rate Cub j Less than or equal to the voltage deviation abnormal threshold Cuby; generating a sub-region voltage stability signal; If the voltage deviation abnormality rate Cub j Greater than the voltage deviation abnormal threshold Cuby; generating a sub-area voltage abnormality signal; determining the abnormal line in the distribution network as the voltage abnormality in sub-area j in branch i.

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