CN107229004A - A kind of localization method of multi branch electric power lines road failure - Google Patents

Abstract

The invention discloses a fault location method for a multi-branch transmission line, which is characterized in that: the location method includes: (1) judging the branch where the fault is located according to the data returned by the spherical unit; The detection results sent back by the installed spherical unit calculate the location of the fault point; (3) Eliminate the influence of different wave velocities on fault location. The beneficial effect of the present invention is that the distributed fault location system realizes the precise location of multi-branch transmission line faults, and only needs to identify the most easily detectable fault initial traveling wave head to complete the fault location, which overcomes the problem of fault traveling waves in multi-branch power transmission. There is a complex refraction and reflection process in the line, which leads to difficulties or misidentification problems when the fault detection device recognizes the head of the traveling wave.

Description

A fault location method for multi-branch transmission lines

technical field

The invention belongs to electric power systems, in particular to a fault location method for multi-branch transmission lines.

Background technique

The high-voltage transmission line is the main artery of the power system, the link between the power plant and the end user, and is responsible for the important task of transmitting electric energy. At the same time, it is the most vulnerable and most prone to failure in the power system. With the sustained and rapid development of my country's power industry, the construction of a "strong smart grid" characterized by informatization, automation, and interaction has also begun to be implemented, which requires the grid to have self-healing capabilities, which requires a complex and flexible power network structure to restore power through other connections while isolating the fault. Therefore, the power system transmission network structure is becoming more and more complex. T-branch (single branch) or even multi-branch transmission lines such as 2-branch and 3-branch have become more and more common as the basic unit of complex power network structure, and will be more widely used.

In this case, the transmission line fault location technology that has been put into use is difficult to guarantee the positioning accuracy or even completely unable to achieve fault location when the transmission line has multiple branches. The reliability and accuracy of the traditional traveling wave ranging method are not affected by the line type, system operation mode, fault resistance and systems on both sides, but it is only applicable to a single line and cannot solve the fault location problem of multi-branch lines. Uncertainty in the value of wave velocity will also lead to a decrease in ranging accuracy.

Contents of the invention

In order to solve the above problems, the present invention provides a multi-branch transmission line fault location method, which solves the problem of multi-branch line fault location.

For realizing its purpose, the technical scheme that the present invention takes is:

A method for locating faults in multi-branch transmission lines, the key is: the locating method includes:

(1) Judging the branch where the fault is located according to the data sent back by the spherical unit;

(2) Calculate the location of the fault point according to the detection results sent back by the spherical unit installed on the line;

(3) Eliminate the influence of different wave speeds on fault location.

Preferably, the positioning method detects the initial traveling wave surge that the fault traveling wave arrives for the first time through the sphere unit installed on each transmission line, captures the first wave head of the fault traveling wave, and monitors the host according to the transmission network The fault branch can be judged when each spherical unit detects the fault traveling wave for the first time, and the line branch where the fault traveling wave is first detected is the line branch where the fault occurs.

Preferably, the location method uses a step-by-step recursive double-ended method to accurately locate the fault location.

Preferably, the positioning method realizes the real-time online measurement of the traveling wave velocity through the spherical unit installed on the power transmission line, and eliminates the influence of different wave velocity on fault location.

Preferably, the locating method adopts a distributed fault locating system, and the distributed fault locating system includes a power transmission line, a sphere unit and a monitoring host, and the sphere unit is installed on the power transmission line.

Preferably, the sphere unit is composed of an inductive power acquisition module, a power management circuit, a traveling wave acquisition module, a microprocessor, and a GSM remote communication module.

Preferably, the power supply of the sphere unit is provided by an inductive power-taking module and a power management circuit; the traveling wave acquisition module and the microprocessor complete the acquisition and processing of the fault traveling wave signal; the initial traveling wave obtained by the GSM remote communication module The time when the wave head reaches the spherical unit is sent to the monitoring host.

Preferably, the monitoring host determines the branch of the fault line according to the installation position of each spherical unit and the data transmitted by the fault traveling wave to each spherical unit, and calculates the fault line based on the time when the fault traveling wave is detected by the spherical unit on the fault branch. The exact location of the occurrence, and then send the positioning result to the mobile terminal.

The beneficial effect of the present invention is that: the fault location method of the multi-branch transmission line realizes the precise location of the fault of the multi-branch transmission line, and only needs to identify the initial traveling wave head of the fault, which is the easiest to detect, to complete the fault location and overcome the fault traveling wave There are complex refraction and reflection processes in multi-branch transmission lines, which lead to difficulties or misidentification problems in the fault detection device when identifying the head of the traveling wave. At the same time, the distributed fault location system can realize the online measurement and compensation of the traveling wave velocity, and eliminate the influence of the uncertainty of the traveling wave velocity on the ranging accuracy. And its positioning accuracy is not affected by line type, system operation mode, and transition resistance.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is the schematic diagram of positioning system of the present invention;

Fig. 2 is the composition schematic diagram of spherical unit of the present invention;

Fig. 3 is a schematic diagram of a multi-branch transmission line network;

Fig. 4 is a schematic diagram of the circuit distribution of the sphere unit;

Figure 5 is a schematic diagram of the principle of the double-ended traveling wave method;

Fig. 6 is a schematic diagram of the structure of the PSCAD simulation circuit;

In the accompanying drawings, 1. the monitoring host, 2. the sphere unit, and 3. the mobile terminal.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In the following description, a lot of specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described here, and those skilled in the art can do it without departing from the meaning of the present invention. By analogy, the present invention is therefore not limited to the specific examples disclosed below.

As shown in Figure 1-6, a multi-branch transmission line fault location method solves the problem of multi-branch fault location.

For realizing its purpose, the technical scheme that the present invention takes is:

A method for locating faults in multi-branch transmission lines, the key is: the locating method includes:

(1) Judging the branch where the fault is located according to the data sent back by the spherical unit 2;

(2) Calculate the fault point position according to the detection result sent back by the spherical unit 2 installed on the line;

(3) Eliminate the influence of different wave speeds on fault location.

In the positioning method, the spherical unit 2 installed on each transmission line is used to detect the initial traveling wave surge that the fault traveling wave arrives for the first time, capture the first wave head of the fault traveling wave, and monitor the host computer 1 according to the The fault branch can be judged when each spherical unit detects the fault traveling wave time for the first time, and the line branch where the fault traveling wave is detected first is the line branch where the fault occurs.

The positioning method adopts the step-by-step recursive double-ended method to accurately locate the fault location.

The positioning method realizes real-time on-line measurement of traveling wave velocity through the spherical unit 2 installed on the transmission line, and eliminates the influence of different wave velocity on fault location.

The locating method adopts a distributed fault locating system, and the distributed fault locating system includes a power transmission line, a sphere unit 2 and a monitoring host 1, and the sphere unit 2 is installed on the power transmission line.

The sphere unit 2 is composed of an induction power acquisition module, a power management circuit, a traveling wave acquisition module, a microprocessor, and a GSM remote communication module.

The power supply of the sphere unit 2 is provided by an induction power-taking module and a power management circuit; the traveling wave acquisition module and the microprocessor complete the acquisition and processing of the fault traveling wave signal; the initial wave head of the traveling wave that the GSM remote communication module will obtain The time of arrival at the spherical unit 2 is sent to the monitoring host 1.

The monitoring host 1 judges the branch of the fault line according to the installation position of each spherical unit 2 and the data transmitted by the fault traveling wave to each spherical unit 2, and calculates the time when the fault traveling wave is detected by the spherical unit 2 on the fault branch. The exact location of the fault, and then send the positioning result to the mobile terminal.

When the present invention is used specifically,

When a ground fault occurs on a transmission line, traveling current and voltage waves will be generated from the fault point to both ends of the line. The fault transient traveling wave has a relatively wide frequency band, ranging from several kilohertz to hundreds of kilohertz, and will produce distortion when passing through high-voltage equipment such as ordinary transformers. Therefore, the sensor used to obtain an undistorted fault traveling wave signal must have sufficient bandwidth. The bandwidth of the Rogowski coil sensor can reach more than 1MHz, which can fully meet the bandwidth requirements of transient fault traveling wave sensing, and can sense transient fault traveling wave signals without distortion. The distributed sphere traveling wave detection unit used in this system is the sphere unit 2 (DFDU, Dis-tributed Fault Detection Unit on Transmission Line) as shown in Figure 2. Composed of power management circuits, it can provide stable and reliable power supply to the system. The Rogowski coil is used as a current sensor, and the obtained current signal is input to the signal conditioning circuit and then output to the A/D conversion sampling module. The current change rate di/dt is used as the input value of the sampling trigger module. When the input value is greater than the threshold dynamically set according to the transmission line current, the sampling module switches from the low-speed sampling mode to the high-speed sampling mode under normal conditions. The main control chip performs signal processing on the faulty traveling wave signal obtained under high-speed sampling, identifies the time when the traveling wave head reaches the detection point, and then sends the time to the monitoring host 1 through the GPS signal.

The fault location method of the multi-branch transmission line is realized by a dome unit 2 (DFDU) installed on the transmission line and a monitoring host 1 . The sphere unit 2DFDU is composed of an induction power acquisition module, a power management circuit, a traveling wave acquisition module, a microprocessor, and a GSM remote communication module. Among them, the induction power acquisition module and the power management circuit provide stable power for the sphere unit to ensure its continuous and stable operation; the traveling wave acquisition module and the microprocessor complete the acquisition and processing of the fault traveling wave signal, and finally the GSM remote communication module will obtain the The time when the initial wave head of the traveling wave reaches the spherical unit 2 is sent to the monitoring host 1 . The monitoring host 1 judges the branch of the fault line according to the installation position of each sphere unit 2 and the data transmitted by the fault traveling wave to each sphere unit 2, and calculates the occurrence of the fault through the time when the sphere unit 2 on the fault branch detects the fault traveling wave exact location. Then the positioning result is sent to the maintenance personnel's mobile terminal 3, providing guarantee for realizing rapid maintenance.

The key to solving multi-branch line fault location is to judge the branch where the fault is located. When a fault occurs, the first problem to be solved by the positioning system is to determine the branch where the fault is based on the data sent back from the spherical unit 2 . Taking the transmission network shown in Figure 3 as an example, the transmission line network includes 20 specific transmission lines, numbered 1 to 20. Each transmission line is equipped with several spherical units 2 according to the length of the transmission line. Taking No. 7 transmission line MN (M and N are the first and last nodes of No. 7 transmission line) as an example, its specific installation on the line As shown in Figure 4. Among them, the yellow sphere in Fig. 4 is the sphere unit 2 (DFDU), which is installed on each transmission line, and the distance between adjacent sphere units 2 is 10km-20km, and the installation number of each line is determined according to the length of the transmission line.

This technology uses the spherical unit 2 installed on each transmission line to detect the initial traveling wave surge when the fault traveling wave arrives for the first time, without considering the complex refraction and reflection of the traveling wave, as long as the first wave head of the fault traveling wave is captured, The initial traveling wave amplitude is large, and the wave head is easy to detect and identify. When a fault occurs on the line MN, the fault traveling wave will propagate from the fault point to the two ends M and N of the line. Therefore, the first to detect the fault traveling wave signal must be the spherical unit 2 installed on the line MN. Therefore, the monitoring host 1 can judge the fault branch according to the time when each spherical unit 2 in the transmission network detects the fault traveling wave for the first time, and the line branch where the fault traveling wave is first detected is the line branch where the fault occurs. .

After the line branch where the fault occurs in the multi-branch line is determined, the location of the fault point can be calculated according to the detection results sent back by the dome unit 2 (DFDU) installed on the line. Take the No. 7 transmission line MN in Figure 3 as an example. M and N are the first and last nodes of the No. 7 transmission line. As shown in Figure 4, there are n spherical units installed on the transmission line MN, numbered from n1 to nn, where n1 is located at the head end of the transmission line MN, and nn is located at the end of the transmission line MN. Take the line MN fault as an example for illustration:

1) The fault occurs between the node M and the installation point of n1 spherical unit 2. At this time, the fault traveling wave flows from the branch node to the line, and the four spherical units 2 around the node M must detect the fault before other spherical units 2 Traveling wave signal, from which it can be judged that the fault occurred at node M, and the fault location can be quickly determined.

2) The fault occurs between node N and the installation point of nn number spherical unit 2. At this time, the fault traveling wave flows from the branch node to the line, and the four spherical units 2 around node N must detect the fault earlier than other spherical units 2 Traveling wave signal, from which it can be judged that the fault occurred at node N, and the fault location can also be quickly determined.

In the above two cases, the fault occurs at the nodes at the first and last ends of the line, and the fault traveling wave can be detected first by the spherical unit 2 around a certain node to quickly determine the fault location at the node.

3) The fault occurs between the installation point of the n _j sphere unit and the 2 installation point of the n _j+1 sphere unit.

In this case, according to the criterion that the spherical unit 2 on the line first detects the fault traveling wave signal, the system can determine that the branch line is a fault-occurring branch. Then, according to the data sent back by the n spherical units 2 on the line, the fault position is precisely located by using the step-by-step recursive double-ended method.

The fault traveling wave propagates from the fault point to the left and right ends respectively, among which the n1~n _j spherical unit 2 detects the fault traveling wave signal propagating to the left, and the n _j ~n _j+1 spherical unit 2 detects the fault traveling wave signal traveling to the right The transmitted fault traveling wave signal is then used to calculate the precise location of the fault by using the absolute time difference between the initial fault traveling wave generated at the fault point and arriving at each spherical unit 2 . The specific method of the traditional double-ended traveling wave method is shown in Figure 5.

Let the moment when the fault initial traveling wave u _FM propagating from the fault point F to the M side arrive at the detection point n _p (1≤p≤j) is t _Fp ; the fault initial traveling wave u _FN propagating from the fault point F to the N side reaches The moment of detecting point n _q (j+1≤q≤n) is t _Fq ; the propagation speed of traveling wave is v, and the distance between two adjacent spherical units 2 is L, then:

In the formula, l _Fp is the distance from the fault point F to the spherical unit n _p on the left side of the fault point, and l _Fq is the distance from the fault point F to the spherical unit n _q on the right side of the fault point. Therefore, it can be obtained from the above equation that the distance from the fault point F to the spherical units n _p and n _q on the left and right sides is:

Where Δt _p,q =t _Fp -t _Fq , Δt _q,p =t _Fq -t _Fp .

The present invention adopts the step-by-step recursive double-ended method, and the time when the fault traveling wave is detected by the first nearest monitoring point on the left side of the fault point is respectively compared with the first, second, ..., nth closest monitoring points on the right side of the fault point. The time difference between the time when the fault traveling wave is detected at the fault point, the time when the second closest monitoring point on the left side of the fault point detects the fault traveling wave is different from the time when the fault traveling wave is detected by the monitoring point closest to the right side of the fault point. Points detect the time of the fault traveling wave, and so on, until the time when the farthest monitoring point on the left side of the fault point detects the fault traveling wave is respectively the first closest, the second closest, ..., the nth closest to the right of the fault point The time difference when the fault traveling wave is detected at the monitoring point is completed, and then the fault location is completed with the above time difference, and the location is normalized and averaged and converted into the distance from the first closest monitoring point on the left side of the fault. This step-by-step recursive double-ended method eliminates the influence of a single monitoring point measurement error or error on the positioning result, and maximizes the accuracy of double-ended positioning.

Taking the fault occurring between the installation point of n _j sphere unit and the installation point of n _j+1 sphere unit 2 as an example, the time when the fault traveling wave is detected by the n _j monitoring point closest to the left of the fault point is respectively The first, second, ..., nth closest monitoring point on the right side of the fault point detects the time difference of the fault traveling wave, and performs fault location.

By calculating the average value from the above formula, the distance between the fault point and the monitoring point _nj can be obtained as:

By analogy, the distance between the fault point and other n1~nj-1 monitoring points on the left is:

According to the installation position of each monitoring point on the transmission line, the above distances can be converted into the distance from the fault point to the nearest detection point nj on the left side of the monitoring point and normalized:

Finally, the distance between the fault point and other monitoring points n ₁ ~ n _j-1 on the left side is brought into Equation (6), and the distance between the fault point and the first closest monitoring point n _j on the left side of the fault can be obtained, that is, the final location result:

It can be seen from formula (7) that the determination of the final fault point requires the use of traveling wave velocity. According to the analysis of traveling wave transmission theory, the wave speed of traveling wave propagating in the transmission line Among them, L and C are the inductance and capacitance values of the wire per unit length, respectively. Therefore, the wave speed of traveling wave transmission is different in different transmission lines. Even for the same line, the parameters of the transmission line may be different at different times, so the wave velocity is actually an uncertain quantity. In actual engineering use, a value close to the speed of light is generally selected according to different transmission line voltage levels to approximate the wave speed, and the value is 0.936c (110kV) to 0.987c (500kV), but the inaccuracy of the value will lead to fault location. reduction in precision.

In this paper, the distributed detection technology is used to realize the real-time online measurement of the traveling wave speed through the spherical unit installed on the transmission line, which can effectively eliminate the influence of different wave speeds. Taking the transmission line MN in Figure 4 as an example, when a fault occurs between detection units n _j and n _j+1 , except for n _j and n _j+1 , other adjacent detection units on the line The time difference Δt of traveling wave transmission is proportional to its installation interval, and the installation interval ΔL is a fixed value, then the actual wave velocity v=ΔL/Δt. In this way, n-2 groups of wave velocity measurements can be obtained. In order to improve measurement accuracy and reliability, the n-2 groups of measurement results are averaged to obtain:

The wave speed is the actual propagation speed of the fault traveling wave on the line when the fault occurs. Bringing this wave velocity value into Equation (7) can obtain a high-precision positioning result that is not affected by wave velocity changes.

The present invention selects a 230kV transmission line structure with four branches for simulation verification. The schematic diagram is shown in FIG. As shown in Figure 6, the transmission line model has four lines in total, and the lengths of line 1, line 2, line 3, and line 4 are 45km, 15km, 30km, and 30km, respectively. Numbers 1 to 12 are the distributed sphere detection units installed on the transmission line. They are installed from the head end of the line. The installation intervals of the sphere units on the same line are the same, all of which are 15km. Among them, the sphere detection units 1 to 4 are installed on the line 1; Sphere detection units 5 and 6 are installed on line 2; sphere detection units 7 to 9 are installed on line 3; sphere detection units 10 to 12 are installed on line 4, and the fault point is located at detection point 2 on line 1 At 10km on the right, the fault occurred 0.02s after the system was started, and the fault lasted for 0.02s. The data sampling rate of the distributed detection unit is 10MHz when a fault occurs, and the time for the fault traveling wave to reach each detection point is shown in Table 1.

It can be seen from Table 1 that detection points 2 and 3 detect the fault initial traveling wave first, so it can be judged that the fault occurred on line 1 and the fault interval is between detection point 2 and detection point 3. According to the propagation time difference between detection point 1 and detection point 2, detection point 3 and detection point 4 in the non-fault interval of line 1, the fault traveling wave can be calculated by substituting into formula (8) Real-time wave speed propagating on this line. Then, using the step-by-step recursive double-ended method, the wave velocity and the time when the fault initial traveling wave arrives at the four detection points 1, 2, 3, and 4 on the fault line are brought into the ranging formula (7) to calculate, which can be calculated The measured distance between the fault location and the detection point 2 is 9.975km, the deviation is only 0.025km, and the positioning accuracy is high. Therefore, this method uses distributed detection units to realize real-time measurement of wave velocity during faults, which eliminates the positioning error caused by the uncertainty of wave velocity, and improves the reliability and accuracy of the positioning results combined with the step-by-step recursive double-ended method.

In the present invention, the initial traveling wave of the fault is detected by the spherical unit 2 installed on the power transmission line, and then the position of the fault point is analyzed and calculated according to the detection result and the installation position of the spherical unit 2, and the distributed spherical detection unit 2 only monitors the initial fault line wave arrival time, that is, the first arriving fault traveling wave signal. The initial traveling wave has the highest signal strength, is easy to monitor, and successfully eliminates the traveling wave measurement and identification error caused by the complex refraction and reflection of the traveling wave. Using the step-by-step recursive double-ended method, through the joint calculation of multiple detection point data, the accuracy and reliability of the positioning results are improved, the positioning error caused by the uncertainty of the wave velocity is eliminated, and the positioning accuracy is improved. At the same time, the positioning accuracy is not affected by The influence of line type, system operation mode and transition resistance.

The distributed fault location system realizes the precise location of multi-branch transmission line faults. It only needs to identify the initial traveling wave head of the fault, which is the easiest to detect, to complete the fault location, which overcomes the complex folding of fault traveling waves in multi-branch transmission lines. , The reflection process leads to the difficulty or misidentification of the fault detection device when identifying the head of the traveling wave. At the same time, the distributed fault location system can realize the online measurement and compensation of the traveling wave velocity, and eliminate the influence of the uncertainty of the traveling wave velocity on the ranging accuracy. And its positioning accuracy is not affected by line type, system operation mode, and transition resistance.

The above are only preferred embodiments of the present invention, and anyone who makes some simple modifications, deformations and equivalent replacements to the present invention according to the content of the present invention falls within the protection scope of the present invention.

Claims (8)

1. a kind of localization method of multi branch electric power lines road failure, it is characterised in that：Described localization method includes：

(1) data passed back according to spheroid unit (2) judge the branch road of guilty culprit；

(2) testing result beamed back according to the spheroid unit (2) installed on circuit calculates position of failure point；

(3) the different influences to fault location of velocity of wave are eliminated.

2. a kind of localization method of multi branch electric power lines road failure according to claim 1, it is characterised in that：Described determines Position method detects the initial row wave that fault traveling wave is reached first by the spheroid unit (2) being installed on each bar transmission line of electricity Gush, catch first wave head of fault traveling wave, monitoring host computer (1) detects event first according to each spheroid unit in the power transmission network The barrier traveling wave time can judge fault branch, and lines branch where the spheroid unit (2) of fault traveling wave is detected at first i.e. The lines branch occurred for failure.

3. a kind of localization method of multi branch electric power lines road failure according to claim 2, it is characterised in that：Described determines Position method is accurately positioned abort situation using recurrence both-end method step by step.

4. a kind of localization method of multi branch electric power lines road failure according to claim 3, it is characterised in that：Described determines Position method realizes the real-time online measuring of traveling wave speed by the spheroid unit being installed on transmission line of electricity, eliminates velocity of wave different Influence to fault location.

5. a kind of localization method of multi branch electric power lines road failure according to claim 4, it is characterised in that：The positioning Method uses distributed fault alignment system, and the distributed fault alignment system includes transmission line of electricity, spheroid unit (2) and prison Main frame (1) is controlled, and the spheroid unit (2) is arranged on transmission line of electricity.

6. a kind of localization method of multi branch electric power lines road failure according to claim 5, it is characterised in that：The spheroid Unit (2) includes sensing electricity-fetching module, electric power management circuit, traveling wave acquisition module, microprocessor, GSM remote communication module groups Into.

7. a kind of localization method of multi branch electric power lines road failure according to claim 6, it is characterised in that：The spheroid The power supply of unit (2) is provided by sensing electricity-fetching module and electric power management circuit；The traveling wave acquisition module and microprocessor are completed The acquisition and processing of fault traveling wave signal；The initial wave head of the traveling wave of acquisition is reached spheroid unit (2) by GSM remote communication modules Time is sent to monitoring host computer (1).

8. a kind of localization method of multi branch electric power lines road failure according to claim 7, it is characterised in that：The monitoring Main frame (1) reaches the data judgement that each spheroid unit (2) is transmitted according to the installation site and fault traveling wave of each spheroid unit (2) Be out of order lines branch, and the Time Calculation for detecting fault traveling wave by the spheroid unit (2) on the fault branch is out of order Positioning result, is then sent on mobile terminal (3) by the accurate location of generation.