CN106482825B - A kind of filtering method of transmission line of electricity corona noise background interference - Google Patents

Abstract

The invention provides a method for filtering out the background interference of corona noise in transmission lines. The method is to arrange a number of noise measuring probes above the ground under the DC line to simultaneously measure the equivalent A sound level; and determine the noise in the measured environment. Spatial attenuation coefficient; based on the audible noise A sound level data obtained by synchronous measurement, the background noise level is calculated in real time according to the relative positional relationship between the noise probe and the line; and the background noise is subtracted from the measurement data containing the background noise to get Corona noise magnitude of transmission lines. The method proposed by the invention is simple and easy to implement, and can realize the real-time and synchronous elimination of background noise interference in the noise measurement process of the DC transmission line, which facilitates the testers to grasp the effective data quantity in the measurement data in time, and reduces the workload of subsequent data processing. It is of great significance for the study of corona noise characteristics and prediction methods of transmission lines.

Description

A method for filtering out the background interference of corona noise in transmission lines

technical field

The invention relates to a background noise filtering method, in particular to a filtering method for the background interference of corona noise of transmission lines.

Background technique

With the rapid development of society and economy, the people are paying more and more attention to environmental protection, especially the corona noise of DC transmission lines. There is a scientific and accurate prediction of the noise level after it is built and put into operation.

Due to the complex generation mechanism of corona noise in DC transmission lines, the prediction method is difficult to characterize as an accurate mathematical model. Generally, it is in the form of empirical formulas, that is, through experiments on different conductors, on the basis of statistical analysis of the measurement results. Combine the empirical formula. At present, the methods recommended by the US BPA (Bonneville Electric Power Authority) and EPRI (US Electric Power Research Institute) are widely used, and these methods are obtained through experimental tests. Therefore, in the transmission line audible noise test, ensuring the authenticity and validity of the test data is the most important prerequisite for the accuracy and effectiveness of the prediction method.

During the audible noise test, the interference of ambient background noise should be avoided as much as possible. However, due to the large geometric size of the transmission line, the test is basically based on outdoor test line segments and actual lines. However, the outdoor test inevitably encounters the problem of background noise interference. The noise test results include not only corona noise components, but also background noise components, such as wind noise, motor vehicle noise on the road, factory machine noise, and residential area. noise, etc. The existence of background noise seriously distorts the audible noise test results of transmission lines, and seriously affects the evaluation, prediction and correction of audible noise of transmission lines. Therefore, there is a need to find a way to filter out the background noise interference from transmission line audible noise measurements.

In terms of filtering technology of audible noise background interference in transmission lines, two methods are generally used at present. The first is to power off the test line segment or the actual line before the noise test, measure the background noise of the point to be measured, then boost the line to the test voltage, and subtract the background noise from the noise result to get the actual corona noise. However, this method is only suitable for areas with relatively constant background noise. If the background noise increases or decreases steadily as a whole during the experiment, it cannot be effectively filtered out. In addition, this method is also not suitable for the actual operation of the DC transmission line because the actual line is impossible to temporarily lose power. The second way is to place a noise test probe away from the test line segment or the actual line, and record the background noise in real time during the test. However, the disadvantage of this method is that in order to avoid the influence of corona noise on the background measurement, the background noise test probe must be arranged at a position far away from the transmission line, but whether the background noise level at this position and the background noise level under the line can be maintained Consistent, there are still uncertainties.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a method for filtering the background interference of corona noise in transmission lines. The method applies noise propagation theory to DC transmission lines, which is simple and easy to implement, and can realize real-time measurement of noise in DC transmission lines. The background noise interference is removed synchronously, which is convenient for testers to grasp the effective data quantity in the measurement data in time, and reduces the workload of subsequent data processing, while ensuring the authenticity and validity of the data, and improving the reliability of the transmission line operation.

The purpose of this invention is to realize through the following technical solutions:

A method for filtering out the background interference of corona noise in transmission lines, the method is used for filtering out the background interference of corona noise in HVDC transmission lines in real time; the method comprises the following steps:

Step 1. Arrange noise measurement probes on the ground below the transmission line in the measurement area;

Step 2. According to the attenuation characteristics of the corona noise in the space propagation process, determine the amount of noise attenuation in the environment without corona noise background interference;

Step 3. All the noise measurement probes perform equivalent continuous A sound level measurement synchronously in the live state of the transmission line, and obtain measurement results in groups;

Step 4. During the measurement of the equivalent continuous A sound level, judge each group of the measurement results according to the judgment principle;

If the measurement result satisfies the determination principle, keep the measurement result of this group;

If the measurement result does not satisfy the determination principle, delete the measurement result in this group, and return to step 3;

Step 5. Real-time analysis is carried out to the retained measurement result, and the corona noise background interference value of the measurement area is obtained;

Step 6. Filter out the background interference of corona noise in the measurement area, and obtain and store the actual corona noise level value of the transmission line.

Preferably, the step 1 includes:

On the ground below the transmission line in the measurement area, with the projection of the positive wire to the ground as the origin, the noise measurement probes are arranged along the vertical path of the transmission line to the measurement points on both sides thereof;

The noise measurement probe is an audible noise measurement probe, and the number of the noise measurement probe is 3 or more;

The position under the line of the positive wire is the required measurement point in the measurement points;

The straight-line distance between any one of the noise measurement probes and the origin is less than or equal to 50m.

Preferably, the step 2 includes:

2-1. Measure and record the straight-line distance from the sound source of the corona noise to where it propagates;

2-2. According to the linear distance from the sound source of the corona noise to its propagation to everywhere and the attenuation characteristics of the corona noise in the space propagation process, the corona noise in the background interference environment without corona noise is obtained. Noise attenuation Δ _AB propagating to any two locations A and B:

ΔAB = k(lg D _A -lg _{D B )} (1)

In the formula, D _A is the straight-line distance from the sound source of the corona noise to the position A, D _B is the straight-line distance from the sound source of the corona noise to the position B, and k is the air attenuation coefficient; Values range from 10 to 13.

Preferably, the step 3 includes:

All the noise measurement probes perform equivalent continuous A sound level measurements synchronously at the same time interval and measurement start and end time under the live state of the transmission line; the time interval is 1 to 10s; every other The measurement results obtained from the measurement of the time interval are all one set of the measurement results.

Preferably, the determination principle in the step 4 includes:

a. The noise test value at the origin is the largest, and as the distance from the positive wire increases, the measurement result gradually decreases;

b. The measurement results of the adjacent noise measurement probes satisfy the following relationship:

In the formula, 1 is the position number that is closer to the positive wire, 2 is the position number that is farther away from the positive wire, AN ₁ is the noise measurement result at position 1, AN ₂ is the noise measurement result at position 2, D1 and D2 sum are the direct distances from the positive lead wire for position ₁ and position ₂ , respectively.

Preferably, the step 5 includes:

5-1. Carry out real-time analysis and ΔAB on the measurement results of the reserved groups, and determine its corona noise _background interference value _ANback :

In the formula, AN _A and AN _B are the noise equivalent A sound level test results at any two positions A and B, respectively, and AN _back is the background noise value;

5-2. If the difference between the AN _backs at different positions is less than 3dB(A), the arithmetic mean of the AN _backs of the corona noise background interference values of all groups is obtained, which is the average voltage of the measurement area. Corona noise background interference value, otherwise, the measurement area should be further divided, and the corona noise background interference value should be calculated separately for each subdivided measurement area.

Preferably, the step 6 includes:

6-1. Filter out the background interference of corona noise in the measurement area, and obtain the _actual corona noise level value AN of the transmission line:

In the formula, AN _measures the noise measurement value of the current transmission line, the average background interference value of the measurement area is AN _average , and AN _is the actual corona noise level value;

6-2. Store the actual corona noise level value _ANreal of the transmission line.

It can be seen from the above technical solutions that the present invention provides a method for filtering out the background interference of corona noise in transmission lines. The method is to arrange a number of noise measurement probes above the ground under the DC line to synchronously perform equivalent A sound determine the spatial attenuation coefficient of noise in the measured environment; based on the audible noise A sound level data obtained by synchronous measurement, according to the relative positional relationship between the noise probe and the line, the background noise level is calculated in real time; The background noise is subtracted from the measured data of , and the corona noise of the transmission line is obtained. The method proposed by the invention is simple and easy to implement, and can realize the real-time and synchronous elimination of background noise interference in the noise measurement process of the DC transmission line, which facilitates the testers to grasp the effective data quantity in the measurement data in time, and reduces the workload of subsequent data processing. At the same time, the authenticity and validity of the data are ensured, and the reliability of the transmission line operation is improved.

Compared with the closest prior art, the technical solution provided by the present invention has the following excellent effects:

1. In the technical solution provided by the present invention, by arranging a number of noise measurement probes above the ground under the DC line, the equivalent A sound level measurement is performed synchronously; the noise spatial attenuation coefficient in the measured environment is determined; based on the synchronous measurement, According to the audible noise A sound level data, the background noise level is calculated in real time according to the relative position relationship between the noise probe and the line; and the background noise is subtracted from the measurement data containing the background noise to obtain the corona noise of the transmission line; It solves the problem that the current common method cannot realize real-time filtering of background noise interference in the process of audible noise measurement of transmission lines, especially when the environmental background noise continues to exist stably, the method is also applicable, and the method of the invention is more practical than other methods in practical use. The method is more accurate and simple.

2. The technical solution provided by the present invention is simple and easy to implement, and can realize the real-time and synchronous elimination of background noise interference during the noise measurement process of the DC transmission line, which is convenient for testers to grasp the effective data quantity in the measurement data in time, and reduces the subsequent data. The workload of processing, while ensuring the authenticity and validity of the data, improves the reliability of the transmission line operation.

3. The technical solution provided by the present invention is widely used and has significant social and economic benefits.

Description of drawings

Fig. 1 is the flow chart of the filtering method of a kind of transmission line corona noise background interference of the present invention;

Fig. 2 is the schematic flow chart of step 2 in the filtering method of the present invention;

Fig. 3 is the schematic flow chart of step 5 in the filtering method of the present invention;

Fig. 4 is the schematic flow chart of step 6 in the filtering method of the present invention;

5 is a schematic diagram of the arrangement position of the noise measurement probe in the application example of the filtering method of the present invention;

6 is a schematic diagram of audible noise raw data measured within a period of time in an application example of the filtering method of the present invention;

7 is a schematic diagram of corona noise data after filtering out the background in the application example of the filtering method of the present invention;

FIG. 8 is a schematic diagram showing the comparison of corona noise data under the positive wire before and after background filtering in an application example of the filtering method of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

As shown in FIG. 1 , the present invention provides a method for filtering out the background interference of corona noise in transmission lines. The method is used to filter out the background interference of corona noise in HVDC transmission lines in real time; the method includes the following steps:

Step 1. Arrange noise measurement probes on the ground below the transmission line in the measurement area;

Step 2. According to the attenuation characteristics of corona noise in the process of space propagation, determine the noise attenuation in the environment without corona noise background interference;

Step 3. All the noise measurement probes are in the live state of the transmission line to perform the equivalent continuous A sound level measurement synchronously, and obtain the measurement results in groups;

Step 4. During the equivalent continuous A sound level measurement, judge each group of measurement results according to the judgment principle;

If the measurement results meet the judgment principle, the group of measurement results will be retained;

If the measurement results do not meet the judgment principle, delete the group of measurement results and return to step 3;

Step 5. Perform real-time analysis on the retained measurement results to obtain the corona noise background interference value in the measurement area;

Step 6. Filter out the background interference of corona noise in the measurement area, and obtain and store the actual corona noise level value of the transmission line.

Step 1, including:

At the ground below the transmission line in the measurement area, take the projection of the positive wire to the ground as the origin, and arrange the noise measurement probes along the vertical path of the transmission line to the measurement points on both sides of it;

Noise measurement probes are audible noise measurement probes, and the number of noise measurement probes is 3 or more;

The position under the line of the positive wire is the required measurement point in the measurement point;

The straight-line distance between any noise measuring probe and the origin is less than or equal to 50m.

As shown in Figure 2, step 2 includes:

2-1. Measure and record the straight-line distance from the source of corona noise to where it spreads;

2-2. According to the straight-line distance from the sound source of corona noise to its propagation and the attenuation characteristics of corona noise in the process of space propagation, it is obtained that the corona noise in the background interference-free environment of corona noise propagates to any two Noise attenuation ΔAB at positions A and _B :

ΔAB = k(lg D _A -lg _{D B )} (1)

In the formula, D _A is the straight-line distance from the sound source of the corona noise to the position A, D _B is the straight-line distance from the sound source of the corona noise to the position B, and k is the air attenuation coefficient; among them, the value range of k is 10 ~13.

Step 3, including:

All noise measurement probes are in the live state of the transmission line, and at the same time interval and measurement start and end time, synchronously carry out the equivalent continuous A sound level measurement; the time interval is 1 to 10s; the measurement results obtained by measuring every other time interval All are a set of measurement results.

Judgment principles in step 4, including:

a. The noise test value at the origin is the largest, and as the distance from the positive wire increases, the measurement result gradually decreases;

b. The measurement results of adjacent noise measurement probes satisfy the following relationship:

In the formula, 1 is the position number that is closer to the positive wire, 2 is the position number that is farther away from the positive wire, AN ₁ is the noise measurement result at position 1, AN ₂ is the noise measurement result at position 2, D1 and D2 sum are the direct distances from the positive lead wire for position ₁ and position ₂ , respectively.

As shown in Figure 3, step 5 includes:

5-1. Perform real-time analysis and Δ _AB on the remaining measurement results of each group to determine the corona noise background interference value AN _back :

In the formula, AN _A and AN _B are the noise equivalent A sound level test results at any two positions A and B, respectively, and AN _back is the background noise value;

5-2. If the difference between the AN _backs at different positions is less than 3dB(A), the arithmetic mean of the corona noise background interference values AN _back of all groups is obtained, which is the average corona noise background interference of the measurement area. Otherwise, the measurement area should be further divided, and the corona noise background interference value should be calculated separately for each subdivided measurement area.

As shown in Figure 4, step 6 includes:

6-1. Filter out the background interference of corona noise in the measurement area, and obtain the _actual corona noise level value AN of the transmission line:

In the formula, AN _measures the noise measurement value of the current transmission line, the average background interference value of the measurement area is AN _average , and AN _is the actual corona noise level value;

6-2. Store the actual corona noise level value AN _real of the transmission line.

The present invention provides an application example of a method for filtering out the background interference of corona noise in transmission lines, which can accurately separate the environmental background noise from the corona noise of DC lines in real time, so as to obtain a method for filtering out the DC transmission lines; this application example The specific steps are:

As shown in Figure 5, a specified number of audible noise measurement probes are arranged at the ground below the DC line. It is recommended to take the projection of the positive wire to the ground as the origin, and arrange the noise measurement probes on both sides of the vertical line path. The number of probes should be 3 or more. ±20m, ±30m..., in order to ensure that the farthest noise measuring probe can monitor the corona noise value, the farthest noise measuring probe should not be more than 50m away from the origin.

(2) Using the attenuation characteristics of corona noise in the process of space propagation, determine the noise attenuation in an ideal environment. Corona Noise Attenuation Satisfaction

ΔAB = k(lg D _A -lg _{D B )} (1)

In the formula, D _A is the direct distance from the sound source to point A, D _B is the direct distance from the sound source to point B, and k is the air attenuation coefficient. For different air conditions, the value of k is different, generally obtained through experiments, the recommended value range of the present invention is 10-13.

(3) In the live state of the DC transmission line, all noise measurement probes are synchronously measured for the equivalent continuous A sound level. The measurement start and end times of the measurement probes at different positions should be kept synchronized, the sampling time should be uniformly set to 1s, and the measurement mode should be equivalent continuous A sound level.

(4) In the test, each group of audible noise measurement results is preprocessed to determine whether the test data is valid. If valid, the group of data is retained, and if invalid, the shuffled data is deleted.

The judgment principle of valid data should meet the following two requirements.

1) The noise test value at the position below the positive wire (origin) is the largest, and with the increase of the distance from the positive wire, the noise test result gradually decreases;

2) The noise results of two adjacent measuring points should satisfy the following relationship

In the formula, 1 is the position number that is closer to the positive wire, 2 is the position number that is farther away from the positive wire, AN ₁ is the noise measurement result at position 1, AN ₂ is the noise measurement result at position 2, D1 and D2 sum are the direct distances from the positive lead wire for position ₁ and position ₂ , respectively.

(5) Real-time analysis of the pre-processed effective test results to determine the level of background noise interference;

The background noise AN _back can be determined by substituting the noise results at two positions in the valid data into the following equation.

In the formula, AN _A and AN _B are the noise equivalent A sound level test results at positions A and B, respectively, and AN _back is the background noise value.

The audible noise value at any two positions can be obtained by formula (2) to obtain a background noise value. When there are many noise measuring probes, there will be multiple background noise values. When the environmental noise at different positions does not change much, it is also The average background noise value of a certain area can be obtained by arithmetic averaging. When the environmental noise levels at different locations are quite different, the measurement area should be subdivided, and the corona noise background interference value should be determined separately for each subdivision measurement area.

(6) The background interference value is subtracted from the current audible noise measurement value to obtain the actual corona noise level of the transmission line and store it. The specific processing method is

In the formula, the measured value is AN _measurement , the background value is AN _back , and the actual corona noise value is AN _real .

As shown in Figures 6 to 8, the effect of the present invention is illustrated by taking the measurement results of the audible noise of the UHVDC test line segment of the State Grid Corporation in Changping, Beijing as an example:

The wire type of the UHV DC test line segment is 4×500mm ² , and the height of the wire to the ground is 15m. Taking the projection of the positive wire to the ground as the origin, three noise measuring probes are arranged at 0m, +20m and -20m respectively, as shown in Figure 2 shown. The height of the noise measurement probe is 1.5m, and the microphones are all pointed to the positive polarity wire. During the noise test, the start and end times are synchronized, the sampling time is uniformly set to 1s, and the measurement mode is equivalent continuous A sound level.

In a quiet time period, apply a higher voltage to the positive-polarity wire, so that the corona noise can be clearly identified and is more than 10dB(A) greater than the background noise. By measuring the audible noise at different locations, combined with theoretical calculations, the noise attenuation coefficient k is 10.9.

A voltage of ±600kV is applied bipolarly to the DC test line segment, and the audible noise measurement probes at three positions below the line perform audible noise measurement synchronously. Fig. 6 is the time-dependent curve of audible noise at different positions within a certain period of time, Fig. 7 is the time-dependent curve of corona noise after background filtering is performed on the original data according to the method of the present invention, and Fig. 8 is the background Comparison of corona noise data before and after filtering out the positive wire. It can be seen from the figure that the real-time filtering method of audible noise background interference proposed by the present invention can effectively filter out the influence of environmental noise superimposed on corona noise. Compared with the original test data, after filtering out the background noise, The corona noise is generally reduced by 0.5~3dB(A), and the effect of filtering out background noise is obvious.

The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify or equivalently replace the specific embodiments of the present invention. , and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are all within the protection scope of the claims of the present invention for which the application is pending.

Claims (2)

1. a kind of filtering method of transmission line of electricity corona noise background interference, the method for filtering out D.C. high voltage transmission in real time Corona noise background interference in route；It is characterized in that, described method includes following steps:

At ground of the step 1. below the transmission line of electricity in measured zone, arrangement noise testing probe；

Attenuation characteristic of the step 2. according to the corona noise during spatial determines that corona free noise background interferes ring Noise attenuation in border；

All the noise testing probe is synchronous to carry out equivalent continuous A sound under the electriferous state of the transmission line of electricity for step 3. Grade measurement, and obtain the measurement result as unit of group；

Step 4. the equivalent continuous A sound level measurement carry out in, according to decision principle judge every group described in measurement result；

If the measurement result meets the decision principle, retain the group measurement result；

If the measurement result is unsatisfactory for the decision principle, the group measurement result, and return step 3 are deleted；

The measurement result that step 5. pair retains is analyzed in real time, obtains the corona noise background interference of the measured zone Value；

Step 6. filters out the corona noise background interference of the measured zone, obtains and store the practical corona of the transmission line of electricity Noise level value；

The step 1, comprising:

At the ground below transmission line of electricity in measured zone, origin is projected as over the ground with positive wire, along the power transmission line The vertical-path on road arranges the noise testing probe to the measurement point of its two sides；

Noise testing probe is that audibly noise testing is popped one's head in, and the quantity of noise testing probe for 3 or 3 with On；

Position under the line of the positive wire be in the measurement point must measuring point；

The linear distance of any one described noise testing probe and the origin, which is respectively less than, is equal to 50m；

The step 2, comprising:

2-1. measures and records the sound source of the corona noise and travels to linear distance everywhere to it；

2-2. travels to linear distance everywhere and corona noise in spatial mistake to it according to the sound source of the corona noise Attenuation characteristic in journey, obtain the corona noise in corona free noise background interference environment propagate to position A at any two, The noise attenuation △ of B_AB:

△_AB=k (lgD_A-lgD_B) (1)

In formula, D_AFor linear distance of the sound source to position A of the corona noise, D_BFor the corona noise sound source to position B Linear distance, k is air attenuation coefficient；Wherein, the value range of k is 10~13；

The step 3, comprising:

All noise testings probe is under the electriferous state of the transmission line of electricity, at the same time and measurement start-stop It is time, synchronous to carry out equivalent continuous A sound level measurement；The time interval is 1 to 10s；Every the survey of a time interval The measurement result measured is measurement result described in one group；

The decision principle in the step 4, comprising:

A. the noise testing value at the origin is maximum, and with the increase away from positive wire distance, the measurement result is gradually Reduce；

B. the measurement result of adjacent noise testing probe meets following relationship:

In formula, 1 is the Position Number being closer away from positive wire, and 2 be the Position Number away from positive wire distance remotely, AN₁ For the noise measurement at position 1, AN₂For the noise measurement at position 2, D₁And D₂Respectively position 1 and position 2 Direct range away from positive wire；

The step 5, comprising:

5-1. passes through △_AB, the measurement result described in each group of reservation analyzed in real time, determines its corona noise background interference values AN_Back:

In formula, AN_A、AN_BNoise equivalent A sound level test result at respectively any two positions A, B, AN_BackFor corona noise background Interference value；

If the AN at 5-2. different location_BackDifference when being respectively less than 3dB (A), it is dry to acquire the corona noise background being all grouped Disturb value AN_BackArithmetic mean number, the average corona noise background interference values AN of the as described measured zone_{It is average}, otherwise, reply is surveyed Region is further is divided for amount, individually seeks corona noise background interference values to measured zone after each subdivision.

2. the method as described in claim 1, which is characterized in that the step 6, comprising:

6-1. filters out the corona noise background interference of the measured zone, obtains the practical corona noise level of the transmission line of electricity Value AN_{It is real}:

In formula, AN_{It surveys}The noise measurement of current transmission line of electricity, the average corona noise background interference values of the measured zone are AN_{It is average}, AN_{It is real}For practical corona noise level value；

6-2. stores the practical corona noise level value AN of the transmission line of electricity_{It is real}。