A grounding fault positioning method based on power distribution data linkage

Abstract

The application relates to a grounding fault positioning method based on power distribution data linkage. The Internet of Things technology is adopted, the characteristics of high grounding fault accuracy of a feeder terminal (FTU) and high coverage of a fault indicator are fully utilized, when a grounding fault occurs in a distribution network line, a collection unit of the fault indicator fuses zero sequence current recording data of a fault indicator collection unit and zero sequence voltage recording data of the feeder terminal (FTU), data linkage is judged, accurate judgment of the grounding fault is realized, and accurate positioning is realized, under the condition that no additional equipment investment is increased, the correctness of grounding fault identification is effectively improved, thereby, the operation cost is reduced, and the operation and maintenance efficiency of the distribution network is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power distribution automation, and particularly relates to a grounding fault positioning method based on power distribution data linkage. BACKGROUND

[0002] The main monitoring equipment of overhead lines of a power distribution network is a feeder terminal (FTU) and a fault indicator, both of which have advantages and disadvantages. The feeder terminal (FTU) has high collection accuracy and high accuracy in grounding fault judgment, but has low coverage. The fault indicator has high coverage, but has low collection accuracy and low accuracy in grounding fault judgment.

[0003] The existing defects are as follows: the main station grounding fault positioning algorithm has high requirements for waveform data quality and poor fault tolerance, especially for positioning of multiple grounding faults occurring at the same time; the fault indicator collection unit itself does not judge grounding faults, and there is no grounding fault indication, so it is difficult to patrol lines. SUMMARY

[0004] The present application aims to solve the problem that the traditional fault indicator can only collect electrical parameters of single-phase lines, which limits the single-phase grounding fault detection algorithm. The present application provides a grounding fault positioning method based on power distribution data linkage, which is based on Beidou / GPS time synchronization, edge computing and other technologies. Through low-cost modification of traditional feeder terminals (FTU) and fault indicators (including collection units and collection units), rapid and accurate judgment and positioning of grounding faults are realized.

[0005] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows: a grounding fault positioning method based on power distribution data linkage, comprising the following steps:

[0006] 1) Under normal operation of the feeder terminal (FTU) and the fault indicator, the network synchronization of the feeder terminal (FTU), the fault indicator collection unit and the fault indicator collection unit is realized based on accurate timing of Beidou / GPS;

[0007] 2) The feeder terminal (FTU) sets grounding fault recording start criteria, including zero sequence voltage start and zero sequence current start. When the grounding fault recording start is started, the feeder terminal (FTU) records the absolute time scale at the fault start time;

[0008] 3) The feeder terminal (FTU) sends the absolute time scale at the start time to the fault indicator collection unit. The fault indicator collection unit calls the fault recording data of the fault indicator collection unit before and after the start time, and synthesizes the zero sequence current I0. The fault recording data before and after the start time includes at least 4 cycles of recording data before the start time and 8 cycles of recording data after the start time;

[0009] 4) The feeder terminal FTU analyzes the fault waveform of the fault recording data through a corresponding algorithm, judges whether it is a ground fault, if it is a ground fault, broadcasts the zero sequence voltage waveform of the feeder terminal FTU to the fault indicator collection unit, and reports the result to the master station;

[0010] 5) After the fault indicator collection unit receives the zero sequence voltage waveform of the feeder terminal FTU, the zero sequence current I0 synthesized in step 3) is combined to start single-phase ground fault discrimination, if it is a ground fault, the result is reported to the master station, and the fault indicator collection unit is indicated by turning over or flashing;

[0011] 6) After the master station receives the ground information of the feeder terminal FTU, the accurate positioning of the fault position is realized according to the ground fault information of the fault indicator under the feeder terminal FTU.

[0012] In an embodiment of the application, the specific implementation mode of the full-network synchronization of the feeder terminal FTU, the fault indicator collection unit and the fault indicator collection unit based on the Beidou / GPS precise timing is:

[0013] (1) The feeder terminal FTU is provided with a Beidou / GPS module, and after obtaining the real-time time, the real-time time is sent to the fault indicator collection unit through LoRa wireless broadcast; or the feeder terminal FTU and the fault indicator collection unit are both provided with a Beidou / GPS module, and the real-time time of the feeder terminal FTU and the fault indicator collection unit is consistent;

[0014] (2) The fault indicator collection unit broadcasts the real-time time to the fault indicator collection unit every 5s, and the fault indicator collection unit saves the sampling position S A , S B , S C of itself immediately after receiving, and the sampling position includes the position in the sampling buffer and the timer count cnt value;

[0015] (3) After receiving the fault indicator collection unit, the A phase saves the position S A of itself, and also broadcasts S A to the BC phase;

[0016] (4) After receiving the broadcast of the A phase, the BC phase calculates the sampling position difference between itself and the A phase, only adjusts the sampling timer by 1us, and ensures that the synchronization accuracy of the three phases is within 20us.

[0017] Compared with the prior art, the application has the following beneficial effects:

[0018] 1. The comprehensive analysis and positioning is not dependent on the master station;

[0019] 2. The fault indicator collection unit has ground fault indication, which is convenient for line inspection;

[0020] 3. Without additional investment in equipment, the low-cost modification of traditional equipment can be realized by adding LoRa modules on the feeder terminal FTU and the fault indicator collection unit. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is the overall scheme diagram of the present application.

[0022] Figure 2 It is the feeder terminal FTU fault judgment logic diagram of the present application.

[0023] Figure 3 It is the fault indicator fault judgment logic diagram of the present application.

[0024] Figure 4 It is the three-phase synchronous fine adjustment schematic diagram. DETAILED DESCRIPTION

[0025] The technical scheme of the present application will be specifically described below in combination with the drawings.

[0026] In view of the problem that the traditional fault indicator can only collect single-phase line electrical parameters, and the single-phase grounding fault detection algorithm is limited, the edge-side cooperative advantages of the feeder terminal FTU and the fault indicator are comprehensively utilized, the fault research and judgment strategy based on the intelligent linkage of both is adopted, and the accurate research and positioning of the single-phase grounding fault are realized to the greatest extent. Figure 1 As shown in the figure, the present application applies the Beidou / GPS time service technology to ensure the time synchronization of the feeder terminal FTU and the fault indicator throughout the network. The zero sequence voltage data of the feeder terminal FTU and the zero sequence current data of the fault indicator collection unit are transmitted to the collection unit of the fault indicator, the ground fault is judged through the fault indicator collection unit, and the response speed and the accuracy of the single-phase grounding fault judgment are comprehensively improved.

[0027] The specific steps are as follows:

[0028] 1) Under the normal operation condition of the feeder terminal FTU and the fault indicator, the network synchronization of the FTU, the fault indicator collection unit and the fault indicator collection unit is realized based on the Beidou / GPS precise time service. The specific implementation is that the feeder terminal FTU is provided with a Beidou / GPS module, after obtaining the real-time time, the real-time time is sent to the fault indicator collection unit through LoRa wireless broadcast, and the fault indicator collection unit sends the real-time time to the fault indicator collection unit through micro-power wireless broadcast;

[0029] 2) The feeder terminal FTU sets the ground fault recording starting criterion, including zero sequence voltage starting and zero sequence current starting, when the ground fault recording starting is started, the FTU records the absolute time scale at the fault starting time;

[0030] 3) The feeder terminal FTU sends the absolute time scale of the recording wave starting moment to the fault indicator collection unit, the collection unit calls its own collection unit to collect the fault recording data (at least including the recording data of 4 cycles before the starting moment and 8 cycles after the starting moment) before and after the moment, and synthesizes the zero sequence current I0;

[0031] 4) After the feeder terminal FTU starts recording, the fault waveform is analyzed by a corresponding algorithm to determine whether it is a ground fault. If it is a ground fault, the zero sequence voltage waveform of the feeder terminal FTU is broadcast to the fault indicator collection unit, and the result is reported to the master station, as shown in Figure 2 ;

[0032] 5) After the fault indicator collection unit receives the zero sequence voltage waveform of the feeder terminal FTU, the zero sequence current I0 synthesized in step 3) is combined to start single-phase ground fault discrimination. If it is a ground fault, the result is reported to the master station, and the fault indicator collection unit is flipped or flashed, as shown in Figure 3 ;

[0033] 6) After the master station receives the ground information of the feeder FTU, the accurate positioning of the fault location is realized according to the ground fault information of the fault indicator of the feeder FTU, the maintenance efficiency is improved, and the maintenance cost is reduced.

[0034] The specific sampling calculation is as follows:

[0035] The Fourier algorithm is used to calculate the effective value of each cycle. It is noted that the increase of the sampling point number can improve the sampling accuracy, but the calculation speed will decrease. The accuracy and speed should be considered comprehensively, and the appropriate sampling point number should be selected.

[0036] The current is a periodic function and can be expressed as:

[0037]

[0038] In the formula, ω represents the fundamental angular frequency, a n and b n are the sine and cosine amplitudes of each harmonic respectively,

[0039] According to the Fourier series principle, a n and b n are respectively:

[0040]

[0041]

[0042] Therefore, the n-th harmonic component can be expressed as:

[0043] i n (t) = b ncos(nωt) + a n sin(nωt)

[0044] Accordingly, the effective value of the n-th harmonic component can be obtained:

[0045]

[0046] The specific three-phase synchronization algorithm is as follows:

[0047] 1) The feeder terminal FTU is provided with a Beidou / GPS module, acquires real-time time, and sends it to the fault indicator collection unit through LoRa wireless broadcast, and the fault indicator collection unit sends it to the fault indicator collection unit through micro-power wireless broadcast; or the feeder terminal FTU and the fault indicator collection unit are provided with Beidou / GPS modules, so that the time of the feeder terminal FTU and the fault indicator collection unit is almost consistent, with an error of 1us;

[0048] 2) The fault indicator collection unit broadcasts its own time to the collection unit every 5s, and the collection unit saves its own sampling position S A , S B , S C , including the position in the sampling buffer and the timer count cnt value;

[0049] 3) After receiving the fault indicator collection unit, the A phase saves its own position S A , and broadcasts S A to the BC phase;

[0050] 4) After receiving the broadcast of A, the BC phase calculates the sampling position difference between itself and the A phase, and only adjusts the sampling timer by 1us, to ensure that the three-phase synchronization accuracy is within 20us.

[0051] The synchronization adjustment is as follows:

[0052] Suppose the timer is set to 78us by default, and one cnt is 1us.

[0053] The sampling position of A is the 100th point in the buffer, and the timer count cnt is 50,

[0054] S A is represented as 100+50(cnt), and

[0055] S B is represented as 125+47(cnt), and the sampling position difference with A is 25 points, which is 3 cnts less

[0056] S C is represented as 90+53(cnt), and the sampling position difference with A is 10 points, which is 3 cnts more

[0057] Timer fine tuning as shown in Figure 4

[0058] B is 3 cnt slower than A, adjust timer to 79us, 3 times to chase A; C is 3 cnt faster than A, adjust timer to 77us, 3 times to wait for A; in this way, after 3 sampling points, ABC achieves sampling synchronization, and BC timer is adjusted back to 78us.

[0059] The above is the preferred embodiment of the present application, any change made according to the technical solution of the present application, as long as the function generated does not exceed the scope of the technical solution of the present application, belongs to the protection scope of the present application.​

Claims

1. A ground fault location method based on power distribution data linkage, characterized in that, Includes the following steps: 1) Under normal operating conditions, the feeder terminal unit (FTU) and fault indicator are synchronized across the entire network based on precise timing via BeiDou / GPS. 2) The feeder terminal unit (FTU) is set with ground fault recording start criteria, including zero-sequence voltage start and zero-sequence current start. When ground fault recording is started, the feeder terminal unit (FTU) records the absolute time stamp of the fault start time. 3) The feeder terminal unit (FTU) sends the absolute time stamp of the startup time to the fault indicator collection unit. The fault indicator collection unit summons the fault waveform data before and after the startup time from its affiliated fault indicator acquisition unit and synthesizes the zero-sequence current I0. The fault waveform data before and after the startup time includes at least the waveform data of the first 4 cycles and the last 8 cycles. 4) The feeder terminal unit (FTU) analyzes the fault waveform of the fault recording data using the corresponding algorithm to determine whether it is a ground fault. If it is a ground fault, the zero-sequence voltage waveform of the feeder terminal unit is broadcast to the fault indicator collection unit and the result is reported to the main station. 5) After receiving the zero-sequence voltage waveform from the feeder terminal FTU, the fault indicator collection unit, combined with the zero-sequence current I0 synthesized in step 3), initiates single-phase ground fault detection. If it is a ground fault, the result is reported to the main station, and the fault indicator collection unit is indicated by flipping the label or flashing the light. 6) After receiving the grounding information from the feeder terminal unit (FTU), the master station then uses the grounding fault information from the fault indicator under the feeder terminal unit (FTU) to accurately locate the fault location. The specific implementation method for achieving full network synchronization of feeder terminal (FTU), fault indicator aggregation unit, and fault indicator acquisition unit based on BeiDou / GPS precise timing is as follows: (1) The feeder terminal (FTU) is equipped with a Beidou / GPS module. After obtaining the real-time time, it is sent to the fault indicator collection unit via LoRa wireless broadcast; or both the feeder terminal (FTU) and the fault indicator collection unit are equipped with Beidou / GPS modules, and the real-time time of the feeder terminal (FTU) and the fault indicator collection unit is consistent. (2) The fault indicator collection unit broadcasts the real-time time to its affiliated fault indicator acquisition unit every 5 seconds. Upon receiving the data, the fault indicator acquisition unit immediately saves its own sampling position S. A S B S C The sampling location includes the position in the sampling buffer and the timer count cnt value; (3) After receiving the fault indicator collection unit, phase A saves its own position S A In addition, there is S A Broadcast to the BC phase; (4) After receiving the broadcast from phase A, phase BC calculates the difference between its own sampling position and phase A, and only performs fine-tuning of the sampling timer, ±1us, to ensure that the three-phase synchronization accuracy is within 20us.

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