Online monitoring and positioning device and method for electricity stealing point of buried cable line

Abstract

The invention discloses an online monitoring and positioning device and method for an electricity stealing point of a buried cable line, and belongs to the technical field of daily operation and maintenance of underground cables commonly used in a power distribution network. The on-line monitoring and positioning method comprises the following steps: connecting a cable line with the on-line monitoring and positioning device, collecting and processing a feedback signal, and positioning an electricity stealing position. The online monitoring and positioning device comprises a controller, a host, a sine carrier module, a pulse width modulation module, a multiplier, an incident terminal, an incident signal coupler, a detection reference module, a feedback processing module, a mathematical calculation module, a receiving terminal and a receiving signal coupler. According to the method, the problem of electricity stealing in the line can be reflected more accurately and quickly, the position of the electricity stealing point can be judged more accurately and quickly in an iteration and comparison mode, accurate searching of the electricity stealing point of the buried cable line in practice is facilitated, and manual operation time and workload are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of daily operation and maintenance of underground cables commonly used in the distribution network, and particularly relates to an on-line monitoring and positioning device and method for power theft points of buried cable lines. Background Technique

[0002] In recent years, with the continuous acceleration of the urbanization process and the rapid development of the social economy, the electricity demand in China has been showing an increasing trend year by year. In cities, due to the need for urban appearance and management, more and more overhead lines have been converted into the form of buried cables. Currently, in the construction of new urban areas and the renovation of old urban areas in China, buried cable lines have become the first choice. However, this change has also brought many challenges to the actual management of cable lines, and the most significant one is the supervision and investigation of power theft problems. Since most of the cable lines in buried cable lines are buried underground, especially the long distance of low-voltage distribution network cable lines, it is impossible to place all lines in the cable underground pipe gallery, and a part of the lines must be directly buried underground, which brings convenience to power thieves, and supervision and search become very difficult. Power theft seriously damages the economic interests of power enterprises and the country, and also has an adverse impact on the normal electricity use of users. It is necessary to conduct scientific supervision and strong crackdown on this behavior.

[0003] However, due to the excessive length and complexity of the buried cable lines in the low-voltage distribution network, the power supply department currently lacks feasible detection and management means. Currently, the commonly used under-voltage method, under-current method, phase-shifting method, and intelligent meter metering, etc. all play a certain role, but the efficiency of anti-power theft is low, the limitations are large, the real-time performance is low, and there is a lack of good initiative and reliability, etc. Therefore, it is necessary to carry out corresponding research on this problem and study new technical solutions that can judge the power theft situation and location of buried cables in real time, quickly, and accurately. Summary of the Invention

[0004] The purpose of the invention is to overcome the deficiencies of the prior art and provide an on-line monitoring and positioning device and method for power theft points of buried cable lines, and solve the problems in the above background technique.

[0005] The purpose of the invention is realized as follows: An on-line monitoring and positioning method for power theft points of buried cable lines, which includes the following steps:

[0006] S1. Connect the cable line with the on-line monitoring and positioning device: including obtaining the detection signal A1(f,t) through the modulation and processing of a multiplier,

[0007] A1(f,t) = U p sin(2πft) × a n

[0008]

[0009] In the formula, the value of n is used to determine the period T c the number of symbols within, satisfying

[0010]

[0011] and taking n as 32 for matching the output frequency f; the detection signal A1(f,t) is injected into the core of the underground cable through the incident signal coupler;

[0012] S2. Perform feedback signal acquisition and processing, including: receiving the feedback signal of the core of the underground cable through the signal coupler and the receiving terminal, and the sampling frequency of the feedback signal is f1, f1≥10f; the waveform of the acquired feedback signal is expressed as A2(f,t),

[0013] A2(f,t) = (λ1t + λ2)U p sin(2πft)×a n

[0014] In the formula, (λ1t + λ2) is the distortion and attenuation situation of the feedback signal compared with the incident detection signal A1(f,t);

[0015] Perform reconstruction and restoration processing on the acquired feedback signal waveform A2(f,t) to reduce the influence of waveform distortion on the calculation result. The processed feedback signal A3(f,t) of the feedback processing module is

[0016]

[0017] Input the processed feedback signal A3(f,t) and the incident detection signal A1(f,t + μ) that has been delayed by μ time at this time into the mathematical calculation module simultaneously, and perform mathematical operations including cross-correlation estimation on them; the cross-correlation estimation operation is

[0018]

[0019] In the formula, S A (t) function is the cross-correlation operation for comparing the similarity of the waveforms of the incident detection signal A1(f,t + μ) and the feedback signal A3(f,t), performing convolution integral operation on the two waveforms, and the obtained S A value is a rational number between [-1, +1]. According to the size of the S A value, judge the power theft situation of the cable line;

[0020] When S A ∈[0,1], power theft occurs in the line. When S AWhen it is in the range of [-1, 0], insulation breakdown occurs in the line, resulting in a grounding fault, and power outage is required for maintenance; when S A = 0 or there is no result, there is no electricity theft in the line.

[0021] S3. Locate the electricity theft position, including:

[0022] Set the propagation speed of the detection signal in the cable core as v, v = 0.85v0, where v0 is the propagation speed of electromagnetic waves in vacuum, which is 3×10^8 m / s; the distance l from the electricity theft position point to the incident signal coupler is

[0023]

[0024] In the formula, μ is the delay time of the incident detection signal. Confirm the actual electricity theft situation according to the calculated distance l of the electricity theft point. If the value of the distance l is consistent with the total length of the entire line, it means that the result represents a branch at the end part, and only need to confirm whether there is a change in the branch; if the value of the distance l is less than the total length of the entire line, it means that there is indeed an electricity theft situation, and dig at this position to confirm.

[0025] An on-line monitoring and positioning device for electricity theft points of buried cable lines, including a controller, a host, a sine carrier module, a pulse width modulation module, a multiplier, an incident terminal, an incident signal coupler, a detection reference module, a feedback processing module, a mathematical calculation module, a receiving terminal and a receiving signal coupler;

[0026] The controller is connected to the sine carrier module, the pulse width modulation module and the mathematical calculation module through signal lines; the controller is used to send control instructions to the sine carrier module and the pulse width modulation module; the sine carrier module is used to output a sine signal with a frequency f of 10 MHz and a peak value U p of 3.3 V; the pulse width modulation module is used to output an m-sequence with a symbol duration of T n , an amplitude a n of ±1 V and an overall period of T c ;

[0027] The incident terminal, the incident signal coupler, the receiving terminal and the receiving signal coupler are all BNC-type terminals and are connected through signal shielding wires;

[0028] The incident signal coupler and the receiving signal coupler are sleeved on the underground cable in a non-contact manner.

[0029] Further, the value of T c of the m-sequence with an overall period of T n is in the range of [0.01T c - 0.5T ctake values between; the incident signal coupler and the received signal coupler are arranged at the end positions of the cable line.

[0030] Advantages of the present invention:

[0031] 1. The on-line monitoring and positioning device for the electricity stealing point of the buried cable line of the present invention can perform on-line monitoring of the electricity stealing situation of the buried cable line of the distribution network in a non-contact manner, and can more accurately and quickly reflect the electricity stealing problem in the line.

[0032] 2. The on-line monitoring and positioning method for the electricity stealing point of the buried cable line of the present invention can judge the position of the electricity stealing point more accurately and quickly through the way of iteration and comparison, which is helpful for accurately finding the electricity stealing point of the buried cable line in practice, and reducing the manual operation time and workload. Description of the drawings

[0033] Figure 1 is the schematic diagram of the implementation of the on-line monitoring and positioning device of the present invention;

[0034] Figure 2 is the flow chart of the on-line monitoring and positioning method of the present invention. Detailed implementation manners

[0035] The following further describes the present invention in detail with reference to the drawings. It should be noted that all the azimuth words such as up, down, front, back, left, and right appearing in the present invention do not limit the present invention, but are only for clearer description and explanation of the present invention.

[0036] As Figure 1-2 shown, this embodiment discloses an on-line monitoring and positioning device and method for the electricity stealing point of a buried cable line, including the following content:

[0037] The first step: Connect the cable line to the on-line monitoring and positioning device;

[0038] 1.1 The on-line monitoring and positioning device includes a controller 1, a host 2, a sine carrier wave module 13, a pulse width modulation module 11, a multiplier 12, an incident terminal 9, an incident signal coupler 8, a detection reference module 3, a feedback processing module 5, a mathematical calculation module 4, a receiving terminal 6, and a received signal coupler 7, and monitors the electricity stealing point of the cable line in a non-contact manner. Among them, the controller 1 is connected to the sine carrier wave module 13, the pulse width modulation module 11, and the mathematical calculation module 4 through signal lines. The incident terminal 9, the incident signal coupler 8, the receiving terminal 6, and the received signal coupler 7 are all BNC type terminals and are connected through signal shielding wires; the incident signal coupler 8 and the received signal coupler 7 are sleeved on the underground cable 10 in a non-contact manner, and it is recommended to be placed at the end positions of the cable line;

[0039] 1.2 Send control instructions from controller 1 to sine carrier module 13 and pulse width modulation module 11. Sine carrier module 13 outputs a sine signal with a frequency f of 10 MHz and a peak value U p of 3.3 V, and pulse width modulation module 11 outputs an m-sequence with a symbol duration of T n , an amplitude a n of ±1 V, and an overall period of T c . Here, the value of T n will be selected within [0.01T c , 0.5T c . After modulation and processing by multiplier 12, the detected signal A1(f, t) will be obtained.

[0040] A1(f, t) = U p sin(2πft) × a n

[0041]

[0042] In the formula, the value of n determines the number of symbols within period T c and satisfies

[0043]

[0044] Here, n is taken as 32 to match the output frequency f; the detected signal A1(f, t) is injected into the core of underground cable 10 through incident signal coupler 8.

[0045] Step 2: Feedback signal acquisition and processing;

[0046] 2.1 After performing the first step operation, receiving signal coupler 7 and receiving terminal 6 start to receive the signals fed back by the core of underground cable 10. The sampling frequency of the feedback signal is f1, f1 ≥ 10f; the waveform of the collected feedback signal is represented as A2(f, t).

[0047] A2(f, t) = (λ1t + λ2)U p sin(2πft) × a n

[0048] In the formula, (λ1t + λ2) characterizes the distortion and attenuation of the feedback signal compared to the incident detected signal A1(f, t). The parameters in (λ1t + λ2) will fluctuate due to differences in actual cables. During the actual acquisition of the feedback signal, the difference in the expression can be ignored, and the directly collected waveform can be directly used as the representation of the feedback signal A2(f, t).

[0049] 2.2 Reconstruct and restore the collected feedback signal A2(f,t) to minimize the impact of waveform distortion on the calculation results. In the feedback processing module 5, the processed feedback signal A3(f,t) is obtained as follows

[0050]

[0051] 2.3 Input the processed feedback signal A3(f,t) and the incident detection signal A1(f,t+μ) that has been delayed by μ time at this time into the mathematical calculation module 4 simultaneously, and perform mathematical operations including cross-correlation estimation on them. Here, the operation method can be changed according to actual needs. In this invention, only the cross-correlation estimation operation is used as an example for illustration, as follows

[0052]

[0053] In the formula, S A (t) function is the cross-correlation operation for comparing the similarity of the waveforms of the incident detection signal A1(f,t+μ) and the feedback signal A3(f,t). The convolution integral operation is performed on the two waveforms, and the obtained S A value is a rational number between [-1, +1]. According to the magnitude of the S A value, judge the power theft situation of the cable line;

[0054] 2.4 When S A ∈[0, 1], power theft may have occurred in the line, and the specific location and exact situation need to be further analyzed; when S A ∈[-1, 0], the probability of power theft in the line is low, but there may have been insulation damage, resulting in a ground fault, and power outage is required for maintenance; when S A = 0 or there is no result, there is no power theft or other problems in the line.

[0055] The third step: Locate the power theft position;

[0056] 3.1 According to the results of step 2.4, for the power theft problem in the case of S A ∈[0, 1], further discrimination and analysis are carried out. Define the propagation speed of the detection signal in the cable core as v, then v = 0.85v0, where v0 is the propagation speed of electromagnetic waves in a vacuum, approximately 3e8 m / s; then the distance l of the power theft position point from the incident signal coupler 8 is

[0057]

[0058] In the formula, μ is the delay time of the incident detection signal;

[0059] 3.2 Confirm the actual power theft situation according to the calculated distance l of the power theft point. If the value of the distance l is consistent with the total length of the entire line, it indicates that the result represents a branch at the end part, and only the change of the branch needs to be confirmed; if the value of the distance l is less than the total length of the entire line, it indicates that there is indeed a power theft situation. Excavate at this position for final confirmation to achieve on-line monitoring and positioning of the power theft point of the buried cable line.

[0060] The above is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and its concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for online monitoring and positioning of electricity theft points in buried cable lines, characterized in that: The following steps are involved: S1, the cable line is connected to the online monitoring and positioning device: including obtaining the detection signal A1 (f, t) through modulation and processing of the multiplier, A1(f,t)=U p sin(2πft)×a n In the formula, the value of n is used to determine the period T c The number of code elements in satisfies And n is taken as 32 to match the output frequency f; the detection signal A1 (f, t) is injected into the cable core of the underground cable through the incident signal coupler; S2, collecting and processing feedback signals; S3. Locate the location of the electricity theft.

2. The method for online monitoring and locating electricity theft points of underground cable lines according to claim 1 is characterized in that: The feedback signal collection and processing includes: receiving the feedback signal of the underground cable core through the signal coupler and the receiving terminal, and the sampling frequency of the feedback signal is f1, f1≥10f; the collected feedback signal waveform is represented by A2(f,t), A2(f,t)=(λ1t+λ2)U p sin(2πft)×a n Where (λ1t+λ2) is the distortion and attenuation of the feedback signal compared to the incident detection signal A1(f,t); The collected feedback signal waveform A2(f, t) is reconstructed and restored to reduce the influence of waveform distortion on the calculation results. The feedback signal A3(f, t) after processing by the feedback processing module is: The processed feedback signal A3 (f, t) and the incident detection signal A1 (f, t+μ) which has been delayed by μ time are simultaneously input into the mathematical calculation module, and mathematical operations including cross-correlation estimation are performed on them; the cross-correlation estimation operation is, In the formula, S A The (t) function is a cross-correlation operation to compare the similarity between the incident detection signal A1 (f, t + μ) and the feedback signal A3 (f, t), and a convolution integral operation is performed on the two waveforms. The obtained S A The value is a rational number between [-1, +1], according to S A The value can be used to determine the power theft situation of the cable line; When S A ∈[0,1], power theft occurs in the line. When S A ∈[-1,0], insulation damage occurs in the line, resulting in a ground fault, requiring power outage for maintenance; when S A =0 or no result, there is no power theft in the line.

3. The method for online monitoring and positioning of electricity theft points in underground cable lines according to claim 1 is characterized in that: The method of locating the electricity theft location includes: The propagation speed of the detection signal in the cable core is set to v, v = 0.85v0, where v0 is the propagation speed of electromagnetic waves in a vacuum, which is 3e8 m / s; the distance l from the power theft location to the incident signal coupler is, Where μ is the delay time of the incident detection signal. The actual electricity theft is confirmed based on the calculated distance l of the electricity theft point. If the value of the distance l is consistent with the total length of the entire line, it means that the result indicates that there is a branch at the end, and it is only necessary to confirm whether the branch has changed. If the value of the distance l is less than the total length of the entire line, it means that electricity theft does exist, and excavation is carried out at this location to confirm it.

4. An online monitoring and positioning device for electricity theft points in buried cable lines, characterized in that: It includes a controller, a host, a sine carrier module, a pulse width modulation module, a multiplier, an incident terminal, an incident signal coupler, a detection reference module, a feedback processing module, a mathematical calculation module, a receiving terminal and a receiving signal coupler; The controller is connected to the sine carrier module, pulse width modulation module and mathematical calculation module through a signal line; the controller is used to send control instructions to the sine carrier module and the pulse width modulation module; the sine carrier module is used to output a frequency f of 10MHz and a peak value U p The pulse width modulation module is used to output a 3.3V sinusoidal signal with a duration of T n , amplitude a n is ±1V and the overall period is T c m-sequence; The incident terminal, incident signal coupler, receiving terminal, and receiving signal coupler are all BNC type terminals and are connected through a signal shielding line; The incident signal coupler and the receiving signal coupler are sleeved on the underground cable in a non-contact manner.

5. The device for online monitoring and positioning of electricity theft points in underground cable lines according to claim 4 is characterized in that: The overall period is T c The m-sequence T n The value of [0.01T c -0.5T c ] to take values; the incident signal coupler and the receiving signal coupler are arranged at the end positions of the cable line.

Images