CN112014693B - Cable partial discharge positioning method and system based on wave speed uncertainty - Google Patents

Abstract

The invention discloses a cable partial discharge positioning method and a system based on wave speed uncertainty, wherein the method comprises the following steps: substituting the estimated propagation velocity v of the signal into a calculation formula of a single-end method, simultaneously measuring the A and B ends of the cable by the single-end method, and recording the positioning result as X _A 、X _B (ii) a The positioning result X obtained by judgment _A 、X _B Whether the precision requirement lambda is met or not, if the precision requirement lambda is not met, calculating the compensation time d _ta 、d _tb And substituting the positioning result into a single-end calculation formula to obtain a positioning result X _A1 、X _B1 Repeatedly calculating until the precision requirement lambda is met, and outputting the corrected wave velocity v'; calculating the wave velocity modification part d _va 、d _vb And substituting the positioning result into a single-end calculation formula to obtain a positioning result X _A2 、X _B2 (ii) a Judging X again _A2 、X _B2 Whether the precision requirement lambda is met or not, if the precision requirement lambda is not met, calculating the compensation time d _ta 、d _tb And will compensate for the time d _ta 、d _tb Substituting into a single-end calculation formula to obtain a positioning result X _An 、X _Bn And repeating the calculation until the precision requirement is met.

Description

Cable Partial Discharge Location Method and System Based on Wave Velocity Uncertainty

technical field

The invention relates to a cable partial discharge location method and system based on wave velocity uncertainty, belonging to the technical field of cable partial discharge location detection.

Background technique

As the most convenient way to use energy in industrial production and residents' daily life in modern society, its demand is also increasing. Power cables are generally located in cable trenches or buried deep underground. Because they do not occupy the ground area and air area, the layout is more flexible, and compared with overhead lines, it has higher safety, power supply reliability, and better aesthetics. , has become more widely used in recent years.

However, most of the cables operate under harsh environmental conditions such as underground or cable trenches. The cables that were put into use in the early stage have also entered the later stages of their service life, and various insulation defects gradually appeared, which gradually led to insulation breakdown, bringing huge economic losses and Security risks. These insulation defects are the main cause of partial discharge activity. Through the location of the partial discharge source, the hidden defects of the cable can be found in time, the maintenance plan can be arranged reasonably, the operation status of the power cable can be grasped in time, and the stable operation of the power grid can be guaranteed.

Contents of the invention

The purpose of the present invention is to overcome the technical defects in the prior art and solve the current partial discharge location problem of power cables. The present invention proposes a cable partial discharge location detection method and system based on wave velocity uncertainty.

The present invention specifically adopts the following technical scheme: a cable partial discharge location method based on wave velocity uncertainty, comprising the following steps:

Step SS1: Estimate the propagation velocity of the partial discharge signal in the cable as v, substitute v into the calculation formula of the single-ended method, and use the single-ended method to measure at both ends of the cable A and B at the same time, and record the positioning results as X _A and X _B ;

Step SS2: Judging whether the positioning results X _A and X _B obtained in step SS1 meet the accuracy requirement λ, if they fail to meet the accuracy requirement λ, calculate the compensation time d _ta and d _tb , and substitute the compensation time d _ta and d _tb into the list Calculate the formula by end method, obtain the positioning results X _A1 and X _B1 , repeat the calculation step SS2 until the accuracy requirement λ is reached, output the corrected wave velocity v' and transfer to step SS3;

Step SS3: When the accuracy requirement λ is met, calculate the wave velocity modification parts d _va and d _vb , and substitute the wave speed modification parts d _va and d _vb into the calculation formula of the single-ended method to obtain positioning results X _A2 and X _B2 ;

Step SS4: Judging again whether X _A2 and X _B2 meet the accuracy requirement λ, if they fail to meet the accuracy requirement λ, calculate the compensation time d _ta , d _tb , and substitute the compensation time d _ta , d _tb into the calculation formula of the single-ended method, The positioning results X _An , X _Bn are obtained, and the calculation step SS4 is repeated until the accuracy requirement is met.

As a preferred embodiment, the step SS1 specifically includes:

Use the estimated propagation velocity v to measure at both ends of the cable at the same time using the single-ended method. The calculation formula of the single-ended method is:

Among them, t _a1 and t _a2 are the time when the first and second waves arrive at terminal A respectively, t _b1 and t _b2 are the time when the first and second waves arrive at terminal B respectively, v is the partial discharge signal in the cable Estimated propagation velocity; L indicates cable line length.

As a preferred embodiment, the step SS2 specifically includes:

The calculation formula for judging whether X _A and X _B meet the accuracy requirements is:

|X _A +X _B -L|<λ;

Among them, L represents the length of the cable line, and λ represents the accuracy.

As a preferred embodiment, the calculation formula of the compensation time in the step SS2 is:

Among them, d _ta is the compensation time of terminal A, d _tb is the compensation time of terminal B, and L indicates the length of the cable line.

As a preferred embodiment, the calculation formulas of the positioning results X _A1 and X _B1 in the step SS2 are:

Among them, d _ta is the compensation time of terminal A, d _tb is the compensation time of terminal B, and L indicates the length of the cable line.

As a preferred embodiment, the calculation formulas of the wave velocity modification parts d _va and d _vb in step SS3 are:

Among them, v _a and v _b are the corresponding wave velocities of the signals at both ends of A and B respectively; d _va is the modified part of the wave speed at the A end of the cable, and d _vb is the modified part of the wave speed at the B end of the cable.

As a preferred embodiment, the calculation formulas of the positioning results X _A2 and X _B2 in the step SS3 are:

Among them, v is the estimated propagation velocity of the partial discharge signal in the cable, t _a1 and t _a2 are the time when the first and second waves arrive at terminal A respectively, and t _b1 and t _b2 are the arrival times of the first and second waves respectively The time at terminal B, v is the estimated propagation velocity of the partial discharge signal in the cable.

As a preferred embodiment, the calculation formulas of the positioning results _XAn and _XBn in the step SS4 are:

Among them, v' is the corrected wave velocity.

The present invention also proposes a cable partial discharge location system based on wave velocity uncertainty, including:

The positioning result acquisition module is used to execute: estimate the propagation velocity of the partial discharge signal in the cable as v, substitute v into the calculation formula of the single-ended method, and use the single-ended method to measure at both ends of the cable A and B at the same time, record the positioning result as X _A , X _B ;

The compensation time generation module is used to perform: judging whether the positioning results X _A and X _B obtained by the positioning result acquisition module meet the accuracy requirement λ, if the accuracy requirement λ cannot be met, then calculate the compensation time d _ta , d _tb , and Substitute the compensation time d _ta and d _tb into the calculation formula of the single-ended method to obtain the positioning results X _A1 and X _B1 , repeat the calculation until the accuracy requirement λ is met, and output the corrected wave velocity v';

The wave velocity compensation generation module is used to execute: when the accuracy requirement λ is met, calculate the wave velocity modification parts d _va and d _vb , and substitute the wave speed modification parts d _va and d _vb into the calculation formula of the single-ended method to obtain the positioning results X _A2 , X _B2 ;

The positioning result generation module is used to perform: judge again whether X _A2 and X _B2 meet the accuracy requirement λ, if they fail to meet the accuracy requirement λ, calculate the compensation time d _ta and d _tb , and substitute the compensation time d _ta and d _tb into Single-ended method calculation formula, obtain positioning results X _An , X _Bn , repeat the calculation until the accuracy requirement is met.

Beneficial effects achieved by the present invention: first, the present invention aims at how to solve the technical problem of current power cable partial discharge location, and proposes a cable partial discharge location detection method and system based on wave velocity uncertainty, which avoids traditional location In the algorithm, the problem that the wave velocity of the partial discharge signal of the cable is selected improperly causes a large positioning error, which avoids the synchronization problem existing in the positioning of the double-ended method; secondly, the present invention uses the arrival time of the first and last partial discharge signals to correct the wave velocity, And using the corrected wave velocity, combined with the principle of single-ended distance measurement, to complete the positioning detection; third, the simulation results show that the method of the present invention has low complexity in principle and can quickly and reliably determine the fault point.

Description of drawings

Fig. 1 is a topological flow chart of the cable partial discharge location method based on wave velocity uncertainty of the present invention.

Fig. 2 is a schematic diagram of the circuit topology of the distribution network equipped with distributed measuring points in the embodiment of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solution of the present invention more clearly, but not to limit the protection scope of the present invention.

Embodiment 1: As shown in FIG. 1 , the present invention proposes a cable partial discharge location detection method based on wave velocity uncertainty, which includes the following four steps.

Step (1): Estimate the propagation velocity of the partial discharge signal in the cable as v, substitute v into the calculation formula of the single-ended method, and use the single-ended method to measure at both ends at the same time, record the positioning results as X _A and X _B :

Among them, t _a1 , t _a2 , t _b1 , t _b2 are the time when the first and second waves arrive at both ends of A and B respectively, and v is the estimated propagation velocity of the partial discharge signal in the cable.

Step (2): Judging whether X _A and X _B meet the precision requirements, if they fail to meet the precision requirements |X _A +X _B -L|<λ, calculate the compensation time d _ta and d _tb , and substitute them into the single-ended method Calculate the formula to get the positioning results X _A1 and X _B1 , and repeat the calculation until the accuracy requirements are met:

Step (3): When the accuracy requirements are met, calculate the wave velocity modification parts d _va and d _vb , and substitute them into the calculation formula of the single-ended method to obtain the positioning results X _A2 and X _B2 :

Among them, v _a and v _b are respectively the corresponding wave velocities of the signals at both ends.

Step (4): Judging again whether X _A2 and X _B2 meet the accuracy requirements. If they fail to meet the accuracy requirements, calculate the compensation time d _ta and d _tb , and substitute them into the calculation formula of the single-ended method to obtain the positioning results X _An and X _Bn . Repeat the calculation until the accuracy requirement is met.

Among them, v' is the corrected wave velocity.

Embodiment 2: The present invention also proposes a cable partial discharge location system based on wave velocity uncertainty, including:

The positioning result acquisition module is used to execute: estimate the propagation velocity of the partial discharge signal in the cable as v, substitute v into the calculation formula of the single-ended method, and use the single-ended method to measure at both ends of the cable A and B at the same time, record the positioning result as X _A , X _B ;

The compensation time generation module is used to perform: judging whether the positioning results X _A and X _B obtained by the positioning result acquisition module meet the accuracy requirement λ, if the accuracy requirement λ cannot be met, then calculate the compensation time d _ta , d _tb , and Substitute the compensation time d _ta and d _tb into the calculation formula of the single-ended method to obtain the positioning results X _A1 and X _B1 , repeat the calculation until the accuracy requirement λ is met, and output the corrected wave velocity v';

The wave velocity compensation generation module is used to execute: when the accuracy requirement λ is met, calculate the wave velocity modification parts d _va and d _vb , and substitute the wave speed modification parts d _va and d _vb into the calculation formula of the single-ended method to obtain the positioning results X _A2 , X _B2 ;

The positioning result generation module is used to perform: judge again whether X _A2 and X _B2 meet the accuracy requirement λ, if they fail to meet the accuracy requirement λ, calculate the compensation time d _ta and d _tb , and substitute the compensation time d _ta and d _tb into Single-ended method calculation formula, obtain positioning results X _An , X _Bn , repeat the calculation until the accuracy requirement is met.

In order to verify the improved single-ended partial discharge location method, the model shown in Figure 2 was built on PSCAD for simulation. The cable model is 64/110kV YJQ03-Z, and its geometric parameters are shown in Table 1. The total length of the cable is 1500m. The cables are cross-connected every 500m, and the metal shielding layers of the cables are grounded after three-phase connection. In the simulation model, the cable lengths are A1=250m, A2=250m, B1=100m, B2=400m, D1=500m. Set the location of the partial discharge source to be 600m from the left end and 900m from the right end.

Table 1

Table 2 shows the comparison of the results of different partial discharge location methods when the empirically estimated propagation velocity v=1.6×108m/s. The accuracy of the partial discharge source location method based on wave velocity uncertainty is much higher than that of the single-ended method and the double-ended method , the error is always within 0.5%.

Table 2

The above is only a preferred embodiment of the present invention, and it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and modifications can also be made. It should also be regarded as the protection scope of the present invention.

Claims (3)

1. The cable partial discharge positioning method based on the wave speed uncertainty is characterized by comprising the following steps of:

step SS1: estimating the propagation speed of partial discharge signal in cable as v, substituting v into single-end methodCalculating formula, measuring at both ends A and B of cable by single-end method, and recording positioning result as X _A 、X _B ；

Step SS2: judging the positioning result X obtained in the step SS1 _A 、X _B Whether the precision requirement lambda is met or not, if the precision requirement lambda is not met, calculating the compensation time d _ta 、d _tb And will compensate for the time d _ta 、d _tb Substituting into a single-end calculation formula to obtain a positioning result X _A1 、X _B1 Repeating the step SS2 until the precision requirement lambda is reached, outputting the corrected wave velocity v', and transferring to the step SS3;

and step SS3: when the precision requirement lambda is met, calculating the wave speed modification part d _va 、d _vb And modifying the wave velocity by a portion d _va 、d _vb Substituting into a single-end calculation formula to obtain a positioning result X _A2 、X _B2 ；

And step SS4: judging X again _A2 、X _B2 Whether the precision requirement lambda is met or not, if the precision requirement lambda is not met, calculating the compensation time d _ta 、d _tb And will compensate for the time d _ta 、d _tb Substituting into a single-end calculation formula to obtain a positioning result X _An 、X _Bn Repeating the calculating step SS4 until the precision requirement is met;

the step SS1 specifically includes:

and measuring the propagation velocity v at two ends of the cable by using a single-end method, wherein the calculation formula of the single-end method is as follows:

wherein, t _a1 、t _a2 The times of arrival of the first and second wave heads at the A terminal, t _b1 、t _b2 Respectively a first and a second wave headThe time of arrival at the B end, v is the estimated propagation speed of the partial discharge signal in the cable; l represents a cable run length;

the calculation formula of the compensation time in the step SS2 is as follows:

wherein, d _ta For A-terminal compensation of time, d _tb Compensating time for the B end, wherein L represents the length of a cable line;

positioning result X in the step SS2 _A1 And X _B1 The calculation formula of (2) is as follows:

wherein, d _ta For the A-terminal, compensate for the time, d _tb Compensating time for the B end, wherein L represents the length of a cable line;

the wave velocity modification section d in the step SS3 _va And d _vb The calculation formula of (2) is as follows:

wherein v is _a 、v _b Are respectively A and BSignals at two ends correspond to wave velocity; d _va Modifying the wave speed for the A end of the cable and d _vb A wave speed modification part at the B end of the cable;

positioning result X in the step SS3 _A2 And X _B2 The calculation formula of (2) is as follows:

where v is the estimated propagation velocity of the partial discharge signal in the cable, t _a1 、t _a2 The times of arrival of the first and second wave heads at the A terminal, t _b1 、t _b2 The time of the first wave head and the time of the second wave head reaching the B end are respectively;

positioning result X in the step SS4 _An And X _Bn The calculation formula of (2) is as follows:

wherein v' is the corrected wave velocity.

2. The method for locating partial discharge of cable according to claim 1, wherein the step SS2 specifically includes:

judgment of X _A 、X _B The calculation formula of whether the accuracy requirement is met is as follows:

|X _A +X _B -L|＜λ；

where L represents the cable run length and λ represents the accuracy.

3. Cable partial discharge positioning system based on wave speed uncertainty, characterized in that includes:

a positioning result obtaining module for executing: estimating the propagation velocity of partial discharge signal in cable as v, substituting v into single-end method calculation formula, measuring at two ends of cable A and B by using single-end method, recording positioning result as X _A 、X _B ；

A compensation time generation module to perform: judging the positioning result X obtained by the positioning result acquisition module _A 、X _B Whether the precision requirement lambda is met or not, if the precision requirement lambda is not met, the compensation time d is calculated _ta 、d _tb And will compensate for the time d _ta 、d _tb Substituting into a single-end calculation formula to obtain a positioning result X _A1 、X _B1 Repeatedly calculating until the precision requirement lambda is met, and outputting the corrected wave velocity v';

a wave velocity compensation generation module to perform: when the precision requirement lambda is met, calculating the wave speed modification part d _va 、d _vb And modifying the wave velocity by a portion d _va 、d _vb Substituting into a single-end calculation formula to obtain a positioning result X _A2 、X _B2 ；

A positioning result generation module for performing: judge X again _A2 、X _B2 Whether the precision requirement lambda is met or not, if the precision requirement lambda is not met, calculating the compensation time d _ta 、d _tb And will compensate for the time d _ta 、d _tb Substituting into a single-end calculation formula to obtain a positioning result X _An 、X _Bn Repeating the calculation until the precision requirement is met;

and measuring the propagation velocity v at two ends of the cable by using a single-end method, wherein the calculation formula of the single-end method is as follows:

wherein, t _a1 、t _a2 The times of arrival of the first and second wave heads at the A terminal, t _b1 、t _b2 Respectively the time of the first wave head and the second wave head to reach the end B, and v is the estimated propagation speed of the partial discharge signal in the cable; l represents a cable run length;

the formula for calculating the compensation time is as follows:

wherein, d _ta For the A-terminal, compensate for the time, d _tb Compensating time for the B end, wherein L represents the length of a cable line;

positioning result X _A1 And X _B1 The calculation formula of (c) is:

wherein d is _ta For A-terminal compensation of time, d _tb Compensating time for the B end, wherein L represents the length of a cable line;

wave velocity modifying section d _va And d _vb The calculation formula of (2) is as follows:

wherein v is _a 、v _b Respectively corresponding wave velocity of signals at the two ends A and B; d _va Modifying the wave speed for the A end of the cable and d _vb A wave speed modification part at the B end of the cable;

positioning result X _A2 And X _B2 The calculation formula of (c) is:

where v is the estimated propagation velocity of the partial discharge signal in the cable, t _a1 、t _a2 The times of arrival of the first and second wave heads at the A terminal, t _b1 、t _b2 The time of the first wave head and the time of the second wave head reaching the B end are respectively;

positioning result X _An And X _Bn The calculation formula of (2) is as follows:

wherein v' is the corrected wave velocity.

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