CN113721115B - Single-phase grounding fault positioning method for neutral point flexible grounding power distribution network - Google Patents
Single-phase grounding fault positioning method for neutral point flexible grounding power distribution network Download PDFInfo
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Abstract
The invention discloses a single-phase earth fault positioning method of a neutral point flexible grounding distribution network, which comprises the steps of firstly, simulating faults of each line section in an off-line state, and solving the iteration interval of virtual fault nodes of each line section; secondly, acquiring negative sequence voltage amplitude values before and after connecting small resistors in parallel with a full-network fault measuring node, and negative sequence current and zero sequence current phases after connecting small resistors in parallel, and inputting characteristic quantities of a fault area into a trained positioning model to determine a fault section; and finally, calculating the negative sequence voltage calculation value of each voltage measurement node under different virtual fault nodes in the fault section, and calculating the fault probability by using the deviation between the negative sequence voltage measurement value and the calculation value, wherein the node with the highest probability is the fault position. The invention does not need to measure zero sequence voltage, does not need to synchronously measure the sequence current phase, has low sampling frequency, and better adapts to the operation characteristic of the flexible grounding power distribution network while less measurement equipment is arranged.
Description
Technical Field
The invention belongs to the technical field of power grid fault positioning, and particularly relates to a single-phase grounding fault positioning method for a neutral point flexible grounding power distribution network.
Background
With the deep development of informatization and intelligent engineering construction of the power distribution network in China, the fault positioning technology has important significance for quickly finding faults, quickly recovering normal system power supply time and reducing social and economic losses. Most of faults are single-phase earth faults, so that the accurate fault location of the power distribution network, particularly single-phase earth faults, can be realized, maintenance personnel can repair the faults in time conveniently, local insulation defects are found, occurrence of cascading faults and even power failure is avoided to the greatest extent, and the method has important significance for improving the power supply reliability and ensures safe and stable operation and economical operation of a power system.
The traditional power distribution network fault positioning method is mostly aimed at a grounding mode, a neutral point flexible grounding mode is adopted to generate a permanent single-phase grounding fault, two types of neutral point grounding modes coexist after the fault, and two typical characteristics can be directly generated. Although the neutral point is grounded by a small resistor, the fault characteristic quantity is obvious, the amplitude change is large, the equipment is easy to detect, and the characteristic that the phase of a fault line is changed by grounding input compensation capacitance of the arc suppression coil cannot be ignored. The existing positioning method utilizing transient information needs high-frequency sampling equipment, and needs to save fault and small-resistance input two abrupt waveform, and has certain limitation. In addition, after the small resistor is input, a larger zero-sequence current is generated, and the zero-sequence voltage is increased, but because the zero-sequence current and the zero-sequence voltage maximum value of the arc suppression coil are not at the fault point, the positioning cannot be realized by simply utilizing the distribution rule of the zero-sequence current or the zero-sequence voltage. Meanwhile, for complex power distribution network topology, the existing section positioning and accurate positioning method needs more measuring nodes, and is high in economic cost, data storage quantity and calculation quantity. Therefore, the fault locating method for the flexible neutral point grounding is researched by utilizing the limited measuring nodes under the power frequency and considering the small resistance and the arc suppression coil of the neutral point, and has important significance for the development, the safe and reliable operation of the power distribution network.
Disclosure of Invention
In order to solve the problems in the background technology, the invention provides a single-phase grounding fault positioning method for a neutral point flexible grounding power distribution network.
In order to achieve the technical purpose and achieve the technical effect, the invention is realized by the following technical scheme: a single-phase earth fault positioning method for a neutral point flexible grounding power distribution network is characterized by comprising the following steps:
step 1): in an offline state, simulating faults of each line section as characteristic quantity, inputting the characteristic quantity into a training model in a Support Vector Machine (SVM) fault section positioning model, and solving the iteration interval of virtual fault nodes of each line section;
Step 2): the method comprises the steps of obtaining negative sequence voltage amplitude values before and after connecting small resistors in parallel with a full-network fault measuring node, and negative sequence current and zero sequence current phase after connecting the small resistors in parallel;
Step 3): judging the region with the largest negative sequence voltage as a fault region, and then inputting the characteristic quantity of the fault region into the training model in the step 1) to determine a fault section;
Step 4): solving the negative sequence voltage calculation value of each voltage measurement node under different virtual fault nodes in the fault section;
step 5): and calculating fault probability by using the deviation between the measured value and the calculated value of the negative sequence voltage, and comparing the fault probability of each virtual fault node of the fault section, wherein the node with the highest probability is the fault position.
Further, in the step 1), the specific steps are as follows:
(a) Inputting fault characteristic quantity: and taking the amplitude of the parallel small-resistance front-rear negative-sequence voltage variation of the measuring node and the corrected projection scaling factor of the zero-sequence current in the negative sequence direction as input data, wherein the projection scaling factor is the ratio k of the difference between the zero-sequence current of each line and the projection of the zero-sequence current in the negative sequence direction to the zero-sequence current, and the expression is as follows:
In the method, in the process of the invention, For the zero sequence current of each line, I H.l is the projection quantity of the zero sequence current of each line in the negative sequence direction, and theta l is the phase difference between the negative sequence current and the zero sequence current of each line;
Since the impedance angle of the transformer and the bus and the impedance angle of the line are not completely equal, that is, the included angle θ between the zero sequence current and the negative sequence current of the fault line is not 0, the scaling factor k is not 0, and if the scaling factor threshold k set =0.1 is set, the corrected projection scaling factor J is:
wherein, when J is 0, the line is a fault line; when J is 1, the line is a non-fault line;
(b) Training a fault section positioning model: the fault characteristic quantity is used as training data, a Radial Basis Function (RBF) kernel function is used for training a fault section positioning model, and the section positioning accuracy of test data of the SVM fault section positioning model is tested;
(c) Solving the iteration interval of virtual fault nodes of each line section: simulating single-phase fault grounding in each line section, setting the fault initial phase angle to be 0 degrees, setting the fault resistance to be 100 omega, setting the positioning error ratio v to be 2%, and substituting the positioning error ratio v into the following formula to obtain the iteration distance delta L:
ΔL＝v％×LV1Vj
where Δl is the iteration spacing of the virtual failed node and L V1Vj is the length of the failed segment V1 Vj.
Further, in the step 3), the specific step of determining the fault area is:
(a) Fault area division: converting a large-scale power distribution network system into a small-scale fault area, and dividing the large-scale power distribution network system into three areas according to the number of measuring nodes and line sections: i, II and III, each area is provided with a statistical node;
(b) Judging a fault area: the statistical node calculates the maximum value of the negative sequence voltage after the parallel small resistors of the measurement nodes of the respective areas, compares and determines the maximum negative sequence voltage of the whole network, and the area where the statistical node of the maximum negative sequence voltage is located is judged to be a fault area. Further, in the step 4), the specific steps are as follows:
(a) Calculating the approximate correction negative sequence current variation of the fault point as the negative sequence current variation of the fault point, wherein the specific expression is as follows:
In the method, in the process of the invention, As the negative sequence current variation of fault point,/>For the approximate correction of the negative sequence current variation quantity of the fault point, pe is the negative sequence current measuring node closest to the fault section, Z T-Pe is the sum of the impedance from the main transformer to the measuring node Pe, and Y Pe-V1 is the sum of the line admittances from the measuring node Pe to the V1 node at the head end of the fault section;
(b) Injecting the same fault negative sequence current variable quantity into each virtual fault node of the fault section in sequence, solving a negative sequence node impedance matrix corresponding to each virtual fault node, and obtaining a corresponding negative sequence voltage calculated value variable quantity matrix.
Further, in the step 5), the specific steps are as follows:
(a) The deviation sigma of the negative sequence voltage calculation value and the measured value is calculated, and the expression is as follows:
σ＝|Uc-Um|
Wherein U c is a negative sequence voltage calculation value, and U m is a negative sequence voltage measurement value;
(b) Sequentially differencing the negative sequence voltage calculated value variation matrix obtained in the step 4) with the negative sequence voltage measured value variation, thereby obtaining a deviation matrix of each virtual fault node Vi, and defining the fault probability P as follows:
Where η Vi is the 2-norm of the deviation matrix of each virtual fault node Vi, η min and η max are the minimum and maximum values, respectively, of all the deviation matrices 2-norms;
(c) And sequentially solving the fault probability of each fault virtual node in the fault section, wherein the fault virtual node corresponding to the maximum probability is the fault node Vf, and the virtual node is the fault position.
Compared with the prior art, the invention has the beneficial effects that:
The invention overcomes the defects of the prior method for positioning the section in the flexible grounding system, and provides a method for positioning the single-phase grounding fault of a neutral point flexible grounding power distribution network, the whole flow of which is shown in figure 1, which comprises the following steps: (1) In an off-line state, simulating faults of each line section as characteristic quantity, inputting the characteristic quantity into a training model in a fault section positioning model of a support vector machine, and solving the iteration interval of virtual fault nodes of each line section; (2) The method comprises the steps of obtaining negative sequence voltage amplitude values before and after connecting small resistors in parallel with a full-network fault measuring node, and negative sequence current and zero sequence current phase after connecting the small resistors in parallel; (3) Judging the region with the largest negative sequence voltage as a fault region, and then inputting the characteristic quantity of the fault region into the training model in the step 1) to determine a fault section; (4) Solving the negative sequence voltage calculation value of each voltage measurement node under different virtual fault nodes in the fault section; (5) And calculating fault probability by using the deviation between the measured value and the calculated value of the negative sequence voltage, and comparing the fault probability of each virtual fault node of the fault section, wherein the node with the highest probability is the fault position.
The invention considers that flexible grounding is the combination of two neutral point grounding modes of a small resistor and an arc suppression coil, analyzes the fault characteristics of the two neutral point grounding modes, takes the negative sequence voltage variation and the zero sequence current correction projection proportionality coefficient as the characteristic quantity of section positioning from the two aspects of amplitude and phase, utilizes the mode identification function of an SVM in the aspect of nonlinear classification, and provides an SVM section positioning algorithm based on the negative sequence voltage variation and zero sequence current projection, and realizes the accurate fault positioning based on the negative sequence voltage variation. According to the method, zero sequence currents are projected to the negative sequence direction, so that current measurement nodes do not need to use neutral point phases as references, synchronization is not needed between the current measurement nodes, the section positioning can be carried out by combining the negative sequence voltage amplitude variation quantity, fault information can be accurately used in multiple directions, the quantity of measurement equipment is reduced to the greatest extent by using limited measurement nodes, good economy is achieved, and meanwhile, the method can still detect the generated small negative sequence voltage variation quantity when special faults such as faults near zero crossing or high resistance faults of phase voltages exist through setting the iteration intervals of virtual fault nodes of each line section.
Drawings
FIG. 1 is a flow chart of a method for locating single-phase earth faults of a neutral-point flexible grounding power distribution network;
fig. 2 is a simulation model diagram of a neutral point flexible grounding power distribution network.
Detailed Description
The invention will be further described with reference to the accompanying drawings.
The invention provides a single-phase earth fault positioning method of a neutral point flexible grounding power distribution network, which comprises the following steps:
(1) In an off-line state, simulating faults of each line section as characteristic quantity, inputting the characteristic quantity into a training model in a support vector machine SVM fault section positioning model, and solving the iteration interval of virtual fault nodes of each line section, wherein the method comprises the following specific steps of:
(a) Inputting fault characteristic quantity: and taking the amplitude of the variation of the negative sequence voltage before and after the parallel small resistors of the measuring nodes and the corrected projection scaling factor of the zero sequence current in the negative sequence direction as input data. The projection proportionality coefficient is the ratio k of the zero sequence current of each line and the projection quantity difference of the zero sequence current in the negative sequence direction to the zero sequence current, and the expression is as follows:
In the method, in the process of the invention, For the zero sequence current of each line, I H.l is the projection quantity of the zero sequence current of each line in the negative sequence direction, and θ l is the phase difference between the negative sequence current and the zero sequence current of each line.
Considering that the impedance angle of the transformer and the bus and the impedance angle of the line cannot be completely equal, namely, the included angle θ between the zero sequence current and the negative sequence current of the fault line is not 0, so that the proportionality coefficient k is not 0, the invention sets a proportionality coefficient threshold value k set =0.1, and then the corrected projection proportionality coefficient J is:
wherein, when J is 0, the line is a fault line; and when J is 1, the line is a non-fault line.
(B) Training a fault section positioning model: and training the fault section positioning model by using the Radial Basis Function (RBF) kernel function by taking the fault characteristic quantity as training data, and testing the section positioning accuracy of the test data of the SVM fault section positioning model.
(C) Solving the iteration interval of virtual fault nodes of each line section: and simulating single-phase fault grounding in each line section, wherein the fault initial phase angle is 0 degrees, the fault resistance is 100 omega, setting the positioning error ratio v to be 2%, and substituting the positioning error ratio v into the following formula to obtain the iteration distance delta L.
ΔL＝v％×LV1Vj
Where Δl is the iteration spacing of the virtual failed node and L V1Vj is the length of the failed segment V1 Vj.
(2) The method comprises the steps of obtaining negative sequence voltage amplitude values before and after connecting small resistors in parallel with a full-network fault measuring node, and negative sequence current and zero sequence current phase after connecting the small resistors in parallel;
(3) And (3) judging the area with the largest negative sequence voltage as a fault area, and then inputting the characteristic quantity of the fault area into the training model in the step 1) to determine a fault section. The specific steps for judging the fault area are as follows:
(a) Fault area division: the invention converts a large-scale power distribution network system into a small-scale fault area. According to the number of measuring nodes and line sections, three areas (I, II, III) are divided, each of which is provided with a statistical node.
(B) Judging a fault area: the statistical node calculates the maximum value of the negative sequence voltage after the parallel small resistors of the measurement nodes of the respective areas, compares and determines the maximum negative sequence voltage of the whole network, and the area where the statistical node of the maximum negative sequence voltage is located is judged to be a fault area.
(4) The method comprises the following specific steps of obtaining negative sequence voltage calculation values of each voltage measurement node under different virtual fault nodes in a fault section:
(a) Calculating the approximate correction negative sequence current variation of the fault point as the negative sequence current variation of the fault point, wherein the specific expression is as follows:
In the method, in the process of the invention, As the negative sequence current variation of fault point,/>For the approximate correction of the fault point, pe is the negative sequence current measuring node closest to the fault section, Z T-Pe is the sum of the impedance of the main transformer to the measuring node Pe, and Y Pe-V1 is the sum of the line admittances of the measuring node Pe to the V1 node of the head end of the fault section.
(B) Injecting the same fault negative sequence current variable quantity into each virtual fault node of the fault section in sequence, solving a negative sequence node impedance matrix corresponding to each virtual fault node, and obtaining a corresponding negative sequence voltage calculated value variable quantity matrix.
(5) Calculating fault probability by using the deviation of the measured value and the calculated value of the negative sequence voltage, comparing the fault probability of each virtual fault node of the fault section, wherein the node with the highest probability is the fault position, and the specific steps are as follows:
(a) The deviation sigma of the negative sequence voltage calculation value and the measured value is calculated, and the expression is as follows:
σ＝|Uc-Um|
Where U c is the negative sequence voltage calculation and U m is the negative sequence voltage measurement.
(B) And (3) sequentially differencing the negative sequence voltage calculated value variation matrix obtained in the step (4) with the negative sequence voltage measured value variation, thereby obtaining a deviation matrix of each virtual fault node Vi. Defining the fault probability P as:
Where η Vi is the 2-norm of the deviation matrix for each virtual fault node Vi, η min and η max are the minimum and maximum, respectively, of all the deviation matrices 2-norms.
(C) And sequentially solving the fault probability of each fault virtual node in the fault section, wherein the fault virtual node corresponding to the maximum probability is the fault node Vf, and the virtual node is the fault position.
Simulation verification
In order to verify the reliability and effectiveness of the invention, an IEEE34 node standard model is improved, a neutral point flexible grounding distribution network simulation model is built as shown in fig. 2, so that the neutral point flexible grounding distribution network simulation model accords with a domestic distribution network system, and the neutral point flexible grounding distribution network simulation model comprises 1 generator, 34 nodes (comprising 28 load nodes) and 33 lines, namely 33 line sections, wherein the voltage level of a power grid is set to 10kV, T1 is a main transformer, the transformation ratio is 110/10.5kV, capacities 100MVA and T2 are grounding transformers, capacity 2MVA, parallel small resistance is 10 omega, the inductance value of an arc suppression coil is 0.1H, the active load is 3MW, and the line type is a cable overhead line mixed line. Taking a fault of 818-820 sections 2.6km from the head end 818 node as an example, the transition resistance R f is set to 1 omega, the fault initial phase angleThe fault time is set to 90 degrees, the fault time is set to 0.1s, the arc suppression coil is set to 0.1H, the parallel small resistor is 10 omega, the sampling frequency is 10kHz, the input time of the parallel small resistor is 0.16s, and the simulation time is 0.2s.
Simulation results in the results of fault region I negative sequence voltage measurement nodes 810, 822 and 826, the result of negative sequence current measurement node 816-2 nearest to fault region 818-820, with an amplitude variation of 168.9A, calculated to obtain a corrected injected negative sequence current169.1A. And using the information of the four measurement nodes to accurately locate faults based on the negative sequence voltage variation. The iteration spacing of sections 818-820 has been obtained in an offline state of 110m, i.e. starting from the head end of the section, one virtual fault node is set per interval 110m, and the last virtual fault node is set at the end of the section. The total length of the 818-820 section is 3.5km, and 32 virtual fault nodes are arranged. To verify the effect of the fault distance, which refers to the distance of the fault point from the line head end 818 node, on the fault accurate positioning method, single phase earth faults were set at different locations in the line sections 818-820, with the remaining conditions unchanged, as shown in table 1 below.
TABLE 1 accurate positioning results at different failure distances
As a result, it was found that 10 different sets of fault distances simulate that the positioning error does not exceed 50m. And other simulation verification proves that the fault accurate positioning method is not influenced by the fault distance, the fault initial phase angle and the fault resistance, and the positioning error is less than or equal to 64m.
While the invention has been described in detail in the foregoing general description and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that modifications and improvements can be made thereto. Accordingly, such modifications or improvements may be made without departing from the spirit of the invention and are intended to be within the scope of the invention as claimed.
Claims (4)
1. A single-phase earth fault positioning method for a neutral point flexible grounding power distribution network is characterized by comprising the following steps:
step 1): in an offline state, simulating faults of each line section as characteristic quantity, inputting the characteristic quantity into a training model in a Support Vector Machine (SVM) fault section positioning model, and solving the iteration interval of virtual fault nodes of each line section;
Step 2): the method comprises the steps of obtaining negative sequence voltage amplitude values before and after connecting small resistors in parallel with a full-network fault measuring node, and negative sequence current and zero sequence current phase after connecting the small resistors in parallel;
Step 3): judging the region with the largest negative sequence voltage as a fault region, and then inputting the characteristic quantity of the fault region into the training model in the step 1) to determine a fault section;
Step 4): solving the negative sequence voltage calculation value of each voltage measurement node under different virtual fault nodes in the fault section;
Step 5): calculating fault probability by using the deviation of the negative sequence voltage measured value and the calculated value, and comparing the fault probability of each virtual fault node of the fault section, wherein the node with the highest probability is the fault position;
the specific steps of the step 1) are as follows:
(a) Inputting fault characteristic quantity: and taking the amplitude of the parallel small-resistance front-rear negative-sequence voltage variation of the measuring node and the corrected projection scaling factor of the zero-sequence current in the negative sequence direction as input data, wherein the projection scaling factor is the ratio k of the difference between the zero-sequence current of each line and the projection of the zero-sequence current in the negative sequence direction to the zero-sequence current, and the expression is as follows:
Wherein I (0) l is the zero sequence current of each line, I H.l is the projection quantity of the zero sequence current of each line in the negative sequence direction, and theta l is the phase difference between the negative sequence current and the zero sequence current of each line;
Since the impedance angle of the transformer and the bus and the impedance angle of the line are not completely equal, that is, the included angle θ between the zero sequence current and the negative sequence current of the fault line is not 0, the scaling factor k is not 0, and if the scaling factor threshold k set =0.1 is set, the corrected projection scaling factor J is:
wherein, when J is 0, the line is a fault line; when J is 1, the line is a non-fault line;
(b) Training a fault section positioning model: the fault characteristic quantity is used as training data, a Radial Basis Function (RBF) kernel function is used for training a fault section positioning model, and the section positioning accuracy of test data of the SVM fault section positioning model is tested;
(c) Solving the iteration interval of virtual fault nodes of each line section: simulating single-phase fault grounding in each line section, setting the fault initial phase angle to be 0 degrees, setting the fault resistance to be 100 omega, setting the positioning error ratio v to be 2%, and substituting the positioning error ratio v into the following formula to obtain the iteration distance delta L:
ΔL＝v％×LV1Vj
where Δl is the iteration spacing of the virtual failed node and L V1Vj is the length of the failed segment V1 Vj.
2. The method for locating single-phase earth faults of a neutral point flexible grounding power distribution network according to claim 1 is characterized by comprising the following steps: in the step 3), the specific steps of determining the fault area are as follows:
(a) Fault area division: converting a large-scale power distribution network system into a small-scale fault area, and dividing the large-scale power distribution network system into three areas according to the number of measuring nodes and line sections: i, II and III, each area is provided with a statistical node;
(b) Judging a fault area: the statistical node calculates the maximum value of the negative sequence voltage after the parallel small resistors of the measurement nodes of the respective areas, compares and determines the maximum negative sequence voltage of the whole network, and the area where the statistical node of the maximum negative sequence voltage is located is judged to be a fault area.
3. The method for locating single-phase earth faults of a neutral point flexible grounding power distribution network according to claim 1 is characterized by comprising the following steps: in the step 4), the specific steps are as follows:
(a) Calculating the approximate correction negative sequence current variation of the fault point as the negative sequence current variation of the fault point, wherein the specific expression is as follows:
wherein delta I (2) f is the negative sequence current variation of the fault point, delta I (2) co is the approximate correction negative sequence current variation of the fault point, pe is the negative sequence current measurement node closest to the fault section, Z T-Pe is the sum of the impedances of the main transformer and the measurement node Pe, and Y Pe-V1 is the sum of the line admittances of the measurement node Pe and the V1 node at the head end of the fault section;
(b) Injecting the same fault negative sequence current variable quantity into each virtual fault node of the fault section in sequence, solving a negative sequence node impedance matrix corresponding to each virtual fault node, and obtaining a corresponding negative sequence voltage calculated value variable quantity matrix.
4. The method for locating single-phase earth faults of a neutral point flexible grounding power distribution network according to claim 1 is characterized by comprising the following steps: in the step 5), the specific steps are as follows:
(a) The deviation sigma of the negative sequence voltage calculation value and the measured value is calculated, and the expression is as follows:
σ＝|Uc-Um|
Wherein U c is a negative sequence voltage calculation value, and U m is a negative sequence voltage measurement value;
(b) Sequentially differencing the negative sequence voltage calculated value variation matrix obtained in the step 4) with the negative sequence voltage measured value variation, thereby obtaining a deviation matrix of each virtual fault node Vi, and defining the fault probability P as follows:
Where η Vi is the 2-norm of the deviation matrix of each virtual fault node Vi, η min and η max are the minimum and maximum values, respectively, of all the deviation matrices 2-norms;
(c) And sequentially solving the fault probability of each fault virtual node in the fault section, wherein the fault virtual node corresponding to the maximum probability is the fault node Vf, and the virtual node is the fault position.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105067948A (en) * | 2015-07-15 | 2015-11-18 | 山东泰景电力科技有限公司 | Small-current grounding line selection device and single-phase grounding detection method |
| CN108899879A (en) * | 2018-07-25 | 2018-11-27 | 国网湖北省电力有限公司电力科学研究院 | Small resistance grounding system earthing protecting method based on zero-sequence current projection coefficient |
| CN112557812A (en) * | 2020-11-24 | 2021-03-26 | 山东理工大学 | Small current ground fault positioning method and system based on Hausdorff distance |
| CN113078611A (en) * | 2021-03-29 | 2021-07-06 | 太原理工大学 | Small resistance grounding system fault protection method based on zero sequence current projection component ratio |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| EP1992954B1 (en) * | 2007-05-18 | 2017-12-13 | ABB Schweiz AG | Method for determining location of phase-to-earth fault |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105067948A (en) * | 2015-07-15 | 2015-11-18 | 山东泰景电力科技有限公司 | Small-current grounding line selection device and single-phase grounding detection method |
| CN108899879A (en) * | 2018-07-25 | 2018-11-27 | 国网湖北省电力有限公司电力科学研究院 | Small resistance grounding system earthing protecting method based on zero-sequence current projection coefficient |
| CN112557812A (en) * | 2020-11-24 | 2021-03-26 | 山东理工大学 | Small current ground fault positioning method and system based on Hausdorff distance |
| CN113078611A (en) * | 2021-03-29 | 2021-07-06 | 太原理工大学 | Small resistance grounding system fault protection method based on zero sequence current projection component ratio |
Non-Patent Citations (2)
| Title |
|---|
| Accurate Fault Location Principle By Means Of Projection Operator for Distributed Parameter Transmission Lines;Ha HengXu;《2006 International Conference on Power System Technology》;第1-5页 * |
| 基于零序电流与电压相位差变化的灵活接地系统故障选线方法;李建蕊;《电网技术》;第45卷(第12期);第4847-4855页 * |
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