Method for determining temperature of cable core of directly-buried submarine cable based on humidity coefficient

Abstract

The invention provides a method for determining the temperature of a cable core of a directly-buried submarine cable based on a humidity coefficient. The method comprises the following steps: S1, measuring the air temperature; s2, measuring the surface temperature of the soil; s3, measuring the surface temperature of the submarine cable; s4, calculating the moisture content of the soil; s5, working current information of the cable is obtained; s6, calculating a humidity coefficient; and S7, calculating the cable core temperature of the submarine cable. According to the method, accurate calculation of the temperature of the cable core of the directly-buried laying submarine cable is achieved by calculating the humidity coefficient, the method is simple and efficient, monitoring of the temperature of the cable core of the submarine cable can be achieved, the utilization rate of the submarine cable is increased, the aging condition of submarine cable insulation is evaluated, and safe and stable operation of a submarine cable power supply system is ensured.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage cable insulation condition assessment, specifically relating to a method for determining the core temperature of a directly buried submarine cable based on the humidity coefficient. Background Technology

[0002] Cross-linked polyethylene (XLPE) possesses excellent heat resistance, insulation, and mechanical properties, and has become the primary insulation material for power cables. High-voltage submarine cables, as key equipment in offshore wind power transmission systems, play a crucial role in connecting wind turbine generators and the onshore power grid. Submarine cables are laid in various ways, with direct burial being the primary method for tidal flat sections. However, due to its inferior heat dissipation compared to subsea sections, direct burial is the weakest link in heat dissipation among all submarine cable laying methods.

[0003] The insulation aging condition of submarine cables is closely related to the core operating temperature. If the cable operates under high load for extended periods, the core operating temperature will remain at a high level, accelerating insulation aging. Conversely, if the cable operates under low load for extended periods, transmission efficiency will decrease, leading to increased cable costs and resource waste. Therefore, calculating the core operating temperature of submarine cables is crucial for assessing the internal insulation aging condition, timely replacement of severely aging cables, extending cable lifespan, and ensuring stable power supply from submarine cables.

[0004] Since temperature sensors cannot directly measure the core temperature of submarine cables, we can only indirectly calculate the core temperature by using the temperature of the cable's outer sheath and the magnitude of the cable's operating current. Furthermore, the ambient temperature and soil moisture content of the environment surrounding the cable can affect the calculation of the core temperature. Therefore, there is an urgent need for an accurate method to calculate the core temperature of submarine cables. This method would provide a basis for maintenance personnel to assess the cable's service performance and is of great significance for ensuring the safe and reliable operation of submarine cables and improving the utilization rate of equipment assets. Summary of the Invention

[0005] The main objective of this invention is to provide a method for determining the core temperature of a directly buried submarine cable based on the humidity coefficient, addressing the problems mentioned above.

[0006] Therefore, the above-mentioned objective of the present invention is achieved through the following technical solution:

[0007] A method for determining the core temperature of a directly buried submarine cable based on the humidity coefficient includes the following steps:

[0008] S1. Measure the air temperature: Measure the air temperature at the cable laying location multiple times at regular time intervals, and record the result as T. i The average of multiple air temperature measurements is taken as the air temperature T. a ;

[0009] S2. Measure soil surface temperature: Measure the soil surface temperature multiple times at regular time intervals, and record the result as T. k The average value of the soil surface temperature measured multiple times is taken as the soil surface temperature T. s ;

[0010] S3. Measure the surface temperature of the submarine cable: Measure the cable surface temperature multiple times at regular time intervals, and record the result as T. m The average of multiple measurements of the cable surface temperature is taken as the cable surface temperature T. b ;

[0011] S4. Calculate the soil moisture content: Randomly collect multiple soil samples of a certain amount near the cable laying location, and record their dry weight M. g Then, dehydration was performed, and the wet weight M of the sample was recorded. s Calculate the average soil moisture content δ;

[0012] S5. Obtain cable operating current information: Collect the cable operating current multiple times from the cable outlet at regular time intervals, and record it as I. k The average value of the recorded operating current is taken as the operating current I of the cable at this time.

[0013] S6. Calculate the humidity coefficient:

[0014]

[0015] In the formula, δ is the average moisture content, and T a T represents the average air temperature. s The average soil surface temperature;

[0016] S7. Calculate the core temperature of the submarine cable:

[0017]

[0018] In the formula, T c Temperature of the submarine cable core, in °C (T). b This represents the average cable surface temperature.

[0019] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0020] As a preferred technical solution of the present invention: the submarine cable is made of cross-linked polyethylene (XLPE).

[0021] As a preferred technical solution of the present invention: In step S1, the average air temperature T a The calculation formula is as follows:

[0022]

[0023] In the formula, T i The air temperature at the cable laying location is measured in a single instance, 1≤i≤5.

[0024] As a preferred embodiment of the present invention: In step S2, the average soil surface temperature T s The calculation formula is as follows:

[0025]

[0026] In the formula, T k The soil surface temperature is measured in a single measurement, 1 ≤ k ≤ 5.

[0027] As a preferred embodiment of the present invention: In step S3, the average cable surface temperature T b The calculation formula is as follows:

[0028]

[0029] In the formula, T m The cable surface temperature is measured in a single measurement, 1 ≤ m ≤ 5.

[0030] As a preferred embodiment of the present invention: In step S4, the formula for calculating the average soil moisture content δ is as follows:

[0031]

[0032] In the formula, M g For soil sample dry weight, 1 ≤ g ≤ 5, M s The wet weight of the soil sample is 1 ≤ s ≤ 5.

[0033] As a preferred embodiment of the present invention: In step S5, the formula for calculating the average cable operating current I is as follows:

[0034]

[0035] In the formula, I k The current is the cable operating current measured in a single measurement, 1≤k≤5.

[0036] Compared with the prior art, the present invention has the following beneficial effects: The present invention achieves accurate calculation of the core temperature of directly buried submarine cables by calculating the humidity coefficient. This method is simple and efficient, and can realize the monitoring of the core temperature of submarine cables, improve the utilization rate of submarine cables, assess the aging condition of submarine cable insulation, and ensure the safe and stable operation of submarine cable power supply systems. Attached Figure Description

[0037] Figure 1 A flowchart illustrating the method for determining the core temperature of a directly buried submarine cable based on the humidity coefficient provided by this invention. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0039] like Figure 1 As shown, a method for determining the core temperature of a directly buried submarine cable based on the humidity coefficient includes the following steps:

[0040] S1. Measure the air temperature: Measure the air temperature at the cable laying location multiple times at regular time intervals (30 seconds in this example), and record the result as T. i The average of multiple air temperature measurements is taken as the air temperature T. a The calculation formula is as follows:

[0041]

[0042] In the formula, T i The air temperature at the cable laying location is measured in a single instance, 1≤i≤5.

[0043] S2. Measure soil surface temperature: Measure the soil surface temperature multiple times at regular time intervals (30 seconds in this example), and record the result as T. k The average value of the soil surface temperature measured multiple times is taken as the soil surface temperature T. s The calculation formula is as follows:

[0044]

[0045] In the formula, T k The soil surface temperature is measured in a single measurement, 1 ≤ k ≤ 5.

[0046] S3. Measure the surface temperature of the submarine cable: Measure the cable surface temperature multiple times at regular time intervals (30 seconds in this example), and record the result as T. m The average of multiple measurements of the cable surface temperature is taken as the cable surface temperature T. b The calculation formula is as follows:

[0047]

[0048] In the formula, T m The cable surface temperature is measured in a single measurement, 1 ≤ m ≤ 5.

[0049] S4. Calculate the soil moisture content: Randomly collect multiple soil samples of a certain amount near the cable laying location, and record their dry weight M. g Then, dehydration was performed, and the wet weight M of the sample was recorded. s The average soil moisture content δ is calculated using the following formula:

[0050]

[0051] In the formula, M g For soil sample dry weight, 1 ≤ g ≤ 5, M s The wet weight of the soil sample is 1 ≤ s ≤ 5.

[0052] S5. Obtain cable operating current information: At certain time intervals (10 seconds in this embodiment), collect the cable operating current multiple times from the cable outlet end, and record it as I. k The average value of the recorded operating currents is taken as the operating current I of the cable at this time. The calculation formula is as follows:

[0053]

[0054] In the formula, I k The current is the cable operating current measured in a single measurement, 1≤k≤5.

[0055] S6. Calculate the humidity coefficient:

[0056]

[0057] In the formula, δ is the average moisture content, and T a T represents the average air temperature. s The average soil surface temperature;

[0058] S7. Calculate the core temperature of the submarine cable:

[0059] T c =κ(T) b +1.824×10 -5 I 2 );

[0060] In the formula, T c Temperature of the submarine cable core, in °C (T). b This represents the average cable surface temperature.

[0061] The submarine cable is made of cross-linked polyethylene (XLPE).

[0062] The technical solution of the present invention has been described in conjunction with the specific experimental procedures shown in the accompanying drawings. However, the scope of protection of the present invention is not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions resulting from such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for determining the core temperature of a directly buried submarine cable based on the humidity coefficient, characterized in that, Includes the following steps: S1. Measure the air temperature: Measure the air temperature at the cable laying location multiple times at regular time intervals, and record the result as T. i The average of multiple air temperature measurements is taken as the air temperature T. a ; S2. Measure soil surface temperature: Measure the soil surface temperature multiple times at regular time intervals, and record the result as T. k The average value of the soil surface temperature measured multiple times is taken as the soil surface temperature T. s ; S3. Measure the surface temperature of the submarine cable: Measure the cable surface temperature multiple times at regular time intervals, and record the result as T. m The average of multiple measurements of the cable surface temperature is taken as the cable surface temperature T. b ; S4. Calculate the soil moisture content: Randomly collect multiple soil samples of a certain amount near the cable laying location, and record their dry weight M. g Then, dehydration was performed, and the wet weight M of the sample was recorded. s Calculate the average soil moisture content δ; S5. Obtain cable operating current information: Collect the cable operating current multiple times from the cable outlet at regular time intervals, and record it as I. k The average value of the recorded operating current is taken as the operating current I of the cable at this time. S6. Calculate the humidity coefficient: In the formula, δ is the average moisture content, and T a T represents the average air temperature. s The average soil surface temperature; S7. Calculate the core temperature of the submarine cable: T c =κ(T b +1.824×10 -5 I 2 ); In the formula, T c Temperature of the submarine cable core, in °C (T). b This represents the average cable surface temperature.

2. The method according to claim 1, characterized in that: The submarine cable is made of cross-linked polyethylene (XLPE).

3. The method according to claim 1, characterized in that: In step S1, the average air temperature T a The calculation formula is as follows: In the formula, T i The air temperature at the cable laying location is measured in a single instance, 1≤i≤5.

4. The method according to claim 1, characterized in that: In step S2, the average soil surface temperature T s The calculation formula is as follows: In the formula, T k The soil surface temperature is measured in a single measurement, 1 ≤ k ≤ 5.

5. The method according to claim 1, characterized in that: In step S3, the average cable surface temperature T b The calculation formula is as follows: In the formula, T m The cable surface temperature is measured in a single measurement, 1 ≤ m ≤ 5.

6. The method according to claim 1, characterized in that: In step S4, the formula for calculating the average soil moisture content δ is as follows: In the formula, M g For soil sample dry weight, 1 ≤ g ≤ 5, M s The wet weight of the soil sample is 1 ≤ s ≤ 5.

7. The method according to claim 1, characterized in that: In step S5, the formula for calculating the average cable operating current I is as follows: In the formula, I k The current is the cable operating current measured in a single measurement, 1≤k≤5.

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