CN111693216A - Cable water inflow detection method based on thermal parameter time change of filling layer material - Google Patents

Abstract

The invention discloses a method for detecting water ingress of a cable based on the time change of thermal parameters of a filling layer material. , the distance between two adjacent temperature detection points is D; in this embodiment, the size of the distance is 20cm, which is an appropriate size to ensure the accuracy of the detection results. S3. After the cable runs stably, record the temperature value of each temperature detection point; S4. Compare each temperature value with the standard temperature of the standard database, and judge whether the temperature value is relatively close to the cable position according to the comparison result. The invention can judge whether the cable enters water online, and can accurately determine the water inflow position, improve the reliability and timeliness of the cable water inflow monitoring, and has great social and economic benefits for ensuring the stability of the power grid operation and the reliable operation of the cable.

Description

A cable water ingress detection method based on the time change of thermal parameters of filling layer material

technical field

The invention relates to a cable detection technology, in particular to a cable water ingress detection method based on the time change of thermal parameters of a filling layer material.

Background technique

With the popularization of cable line construction and the wide application of power cables, cable-related faults occur more and more frequently, and line faults caused by cable water ingress are more common. In order to prevent the water from spreading after the cable enters the water, a filler layer is usually provided in the power cable. The filling layer is made of a material with water-swelling properties, which expands rapidly in the presence of water and diverts the water to diffuse along the longitudinal direction of the cable to achieve water-blocking.

At present, there is a lack of effective online detection methods for cable water ingress, and there is no clear indicator to characterize the cable water ingress. The research and development of a cable water ingress detection method to realize online timely and accurate monitoring has great social and economic benefits to ensure the stability of power grid operation and the reliable operation of cables.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art, and to provide a cable water ingress detection method based on the time change of the thermal parameters of the filling layer material. The cable water ingress detection method based on the time change of the thermal parameters of the filling layer material can detect whether the cable has entered the water online, and can locate the water ingress position to monitor the cable in real time.

The purpose of the present invention is achieved through the following technical solutions: this cable water ingress detection method based on the time change of the thermal parameters of the filling layer material comprises the following steps:

S1. A temperature sensor is built into the filling layer of the cable;

S2. Calibrate a plurality of temperature detection points along the axis of the cable, and the distance between two adjacent temperature detection points is D;

S3. After the cable runs stably, record the temperature value of each temperature detection point;

S4. Compare each temperature value with the standard temperature of the standard database, and judge whether the cable position relative to this temperature value is water infiltrated according to the comparison result.

In step S1, the temperature sensor is a distributed optical fiber temperature sensor, and the distributed optical fiber temperature sensor is distributed in a spiral or a straight line.

The standard temperature of the standard database in step S4 is obtained by collecting the normal cables under the condition of specific parameters, and the specific parameters include the running time of the cables, the humidity and the load on the cables.

The process of establishing the standard database is as follows:

Select a certain length of normal cable, mark the temperature measurement nodes at a certain distance along the axis of the cable, and sort the temperature measurement nodes;

After the cable runs normally, under certain parameters, the temperature values measured by each temperature measurement node will save the standard temperature data every 30s ~ 90s, and process the saved standard data every 1h ~ 3h to complete the standard temperature data. Curve and fitting, and then use the induction algorithm to systematically summarize the variation characteristics of standard temperature data under specific parameters to form a standard database.

The temperature values measured by each temperature measuring node save the standard temperature data every 60s, and process the saved standard data every 2h.

Described in step S4, the specific process that each temperature value is compared with the standard temperature of standard database is as follows:

Find the standard temperature of the temperature detection point corresponding to the temperature value in the standard database, the difference T between the standard temperature and the temperature value, if the difference T exceeds the threshold K, the cable at the temperature detection point corresponding to the temperature value will enter the water , where the threshold value is the difference in temperature characteristics of the filling layer material before and after the filling layer temperature measurement point is filled with water at this point.

Compared with the prior art, the present invention has the following advantages:

1. This cable water ingress detection method based on the time change of the thermal parameters of the filling layer material compares the temperature detected at the temperature detection point detected online with the pre-made standard database to determine whether the cable has entered water, and can accurately determine Inlet location.

2. This cable water inflow detection method based on the time change of thermal parameters of the filling layer material improves the reliability and timeliness of the cable water inflow monitoring, and has great social and economic benefits to ensure the stability of the power grid operation and the reliable operation of the cable.

Description of drawings

FIG. 1 is a flow chart of the method for detecting water ingress of a cable based on the time change of thermal parameters of the filling layer material according to the present invention.

FIG. 2 is an arrangement diagram of a distributed optical fiber temperature sensor according to Embodiment 1 of the present invention.

3 is an arrangement diagram of a distributed optical fiber temperature sensor according to Embodiment 2 of the present invention.

Among them, 1 is a cable, 2 is a filling layer, and 3 is a distributed optical fiber temperature sensor.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

Example 1

As shown in Figure 1, the cable water ingress detection method based on the time change of the thermal parameters of the filling layer material includes the following steps:

S1. A temperature sensor is built into the filling layer of the cable; the temperature and temperature sensor is a distributed optical fiber temperature sensor. As shown in FIG. 3 , the distributed optical fiber temperature sensor in this embodiment presents a spiral distribution.

S2, calibrate a plurality of temperature detection points along the axis direction of the cable, the distance between two adjacent temperature detection points is D, and at the same time, the temperature detection points are sorted along the axis direction of the cable; the size of the distance in this embodiment is 20cm, an appropriate size to ensure the accuracy of the test results.

S3. After the cable runs stably, record the temperature value of each temperature detection point;

S4. Compare each temperature value with the standard temperature of the standard database, and judge whether the cable position relative to this temperature value is water infiltrated according to the comparison result.

Specifically, the filling layer of the cable has the characteristics of water absorption and expansion. After the filling layer absorbs water and expands, its thermal parameters will change within a certain period of time. Distributed optical fiber temperature sensors are installed in the filling layer, and the temperature changes of the filling layer are monitored by the distributed optical fiber temperature sensor, and then the detected temperature is compared with the standard temperature of the standard database to judge whether the cable enters the water and the position of the water entering. .

The specific process of comparing each temperature value with the standard temperature of the standard database is as follows: find the standard temperature of the temperature detection point corresponding to the temperature value in the standard database, the difference T between the standard temperature and the temperature value, and if the difference T exceeds the threshold K , the cable at the temperature detection point corresponding to the temperature value enters water, and the threshold value is the difference in temperature characteristics of the filling layer material before and after the temperature measurement point of the filling layer enters the water at this point. In this comparison process, the standard temperature in the standard database is compared with the temperature value detected by the temperature detection point under the parameters of the same environment temperature, humidity, load on the cable, and cable running time to obtain the standard temperature and the detected temperature. The difference T between the values, to see whether the difference exceeds the threshold K, so as to determine whether water enters the cable corresponding to the temperature detection point here.

The standard temperature of the standard database in step S4 is obtained by collecting the normal cables under the condition of specific parameters, and the specific parameters include the running time of the cables, the humidity and the load on the cables.

The process of establishing the standard database is as follows:

Select a certain length of normal cable, mark the temperature measurement nodes at a certain distance along the axis of the cable, and sort the temperature measurement nodes;

After the cable runs normally, under certain parameters, the temperature values measured by each temperature measurement node will save the standard temperature data every 30s ~ 90s, and process the saved standard data every 1h ~ 3h to complete the standard temperature data. Curve and fitting, and then use the induction algorithm to systematically summarize the variation characteristics of standard temperature data under specific parameters to form a standard database. Specifically, the temperature values measured by each temperature measurement node save the standard temperature data every 60s, and process the saved standard data every 2h, and the distance between two adjacent temperature measurement nodes is 0.5m.

Example 2

The cable water ingress detection method based on the time change of the thermal parameters of the filling layer material is the same as the embodiment 1 except for the following technical features: As shown in FIG. 2 , the distributed optical fiber temperature sensor is distributed in a spiral or a straight line. This distribution method is convenient for the arrangement of the distributed optical fiber temperature sensor, the operation is convenient, and the temperature of the temperature detection point can also be accurately detected.

The above-mentioned specific embodiments are the preferred embodiments of the present invention, and do not limit the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solutions of the present invention are included in the protection scope of the present invention. within.

Claims (6)

1. A cable water inlet detection method based on thermal parameter time change of a filling layer material is characterized by comprising the following steps: the method comprises the following steps:

s1, placing a temperature sensor in the filling layer of the cable;

s2, calibrating a plurality of temperature detection points along the axial direction of the cable, wherein the distance between every two adjacent temperature detection points is D;

s3, recording the temperature value of each temperature detection point after the cable runs stably;

and S4, comparing each temperature value with the standard temperature of the standard database, and judging whether the cable position where the temperature value is relative is water or not according to the comparison result.

2. The method for detecting the water inflow of the cable based on the time change of the thermal parameters of the filling layer material according to claim 1, wherein the method comprises the following steps: in step S1, the temperature sensor is a distributed optical fiber temperature sensor, and the distributed optical fiber temperature sensor is distributed spirally or linearly.

3. The method for detecting the water inflow of the cable based on the time change of the thermal parameters of the filling layer material according to claim 1, wherein the method comprises the following steps: the standard temperature of the standard database in step S4 is obtained by collecting the normal cable under the condition of specific parameters including the cable running time, humidity and the load on the cable.

4. The method for detecting the water inflow of the cable based on the time change of the thermal parameters of the filling layer material according to claim 3, wherein the method comprises the following steps: the standard database is established specifically as follows:

selecting a cable with a certain normal length, marking temperature measurement nodes according to a certain distance along the axial direction of the cable, and sequencing the temperature measurement nodes;

after the cable normally runs, under specific parameters, the temperature values measured by each temperature measuring node are stored once every 30-90 s for standard temperature data, the stored standard data are processed every 1-3 h to complete the curve and fitting of the standard temperature data, and then the change characteristics of the standard temperature data under the specific parameters are summarized by using an induction algorithm system to form a standard database.

5. The method for detecting the water inflow of the cable based on the time change of the thermal parameters of the filling layer material according to claim 4, wherein the method comprises the following steps: and storing the standard temperature data once every 60s by the temperature value measured by each temperature measuring node, and processing the stored standard data every 2 h.

6. The method for detecting the water inflow of the cable based on the time change of the thermal parameters of the filling layer material according to claim 1, wherein the method comprises the following steps: in step S4, the specific process of comparing each temperature value with the standard temperature of the standard database is as follows:

and finding a standard temperature of a temperature detection point corresponding to the temperature value in a standard database, and finding a difference value T between the standard temperature and the temperature value, wherein if the difference value T exceeds a threshold value K, the cable water enters the temperature detection point corresponding to the temperature value, and the threshold value is the temperature characteristic change difference of the filling layer material before and after the filling layer temperature measurement point enters the water at the point.

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