阅读说明：本技术 一种220千伏电缆动态增容系统及方法 (Dynamic capacity increasing system and method for 220 KV cable ) 是由 李响 岳灵平 金国亮 张鹏 李龙 陆利平 戴建华 俞伟勇 于 2021-08-16 设计创作，主要内容包括：本发明公开了一种220千伏电缆动态增容系统及方法,为了解决无法实时计算电缆导体温度和载流量,且没有改善电缆周围散热条件或增加强制降温措施的问题,包括：若干个光纤测温模块,用于检测电缆外表面温度和环境温度；若干个点伏光栅模块,用于测量排管口电缆温度；若干个热电偶模块,用于检测土壤温度；若干个护层电流模块,用于采集电缆的实时运行电流；若干个散热降温模块,用于改善电缆周围散热条件或增加强制降温措施；诊断分析模块,用于实时导体温度与载流量计算。本发明的有益效果是：通过本装置可以改善电缆周围散热条件或增加强制降温措施；通过本方法可以计算实时导体温度与载流量。(The invention discloses a 220 KV cable dynamic capacity increasing system and a method, aiming at solving the problems that the conductor temperature and the current-carrying capacity of a cable cannot be calculated in real time, and the heat dissipation condition around the cable is not improved or forced cooling measures are not added, and the method comprises the following steps: the optical fiber temperature measuring modules are used for detecting the temperature of the outer surface of the cable and the ambient temperature; the point volt grating modules are used for measuring the temperature of the cable at the pipe arranging opening; the thermocouple modules are used for detecting the soil temperature; the sheath current modules are used for collecting the real-time running current of the cable; the plurality of heat dissipation and cooling modules are used for improving the heat dissipation conditions around the cable or increasing forced cooling measures; and the diagnosis analysis module is used for calculating the conductor temperature and the current-carrying capacity in real time. The invention has the beneficial effects that: the device can improve the heat dissipation condition around the cable or increase the forced cooling measure; the method can be used for calculating the real-time conductor temperature and the current-carrying capacity.)

1. A 220 kv cable dynamic capacitance enhancement system, comprising:

the optical fiber temperature measuring modules (1) are used for detecting the temperature of the outer surface of the cable and the ambient temperature;

the point volt grating modules (2) are used for measuring the temperature of the cable at the pipe arranging opening;

the thermocouple modules (3) are used for detecting the soil temperature;

the sheath current modules (4) are used for collecting the real-time running current of the cable;

the heat dissipation and cooling modules (5) are used for improving the heat dissipation conditions around the cables or adding forced cooling measures;

and the diagnostic analysis module (6) is used for calculating the conductor temperature and the current-carrying capacity in real time.

2. The 220 kV cable dynamic capacity increasing system according to claim 1, wherein the plurality of fiber temperature measuring modules (1), the plurality of point volt grating modules (2), the plurality of thermocouple modules (3), the plurality of sheath current modules (4) and the plurality of heat dissipation and temperature reduction modules (5) are connected with the diagnostic analysis module (6).

3. The 220 KV cable dynamic capacity increasing system according to claim 1 or 2, wherein the plurality of heat dissipation and temperature reduction modules (5) comprise a plurality of low thermal resistance filling units (51) filled in the cable duct sections.

4. The 220 kV cable dynamic capacity increasing system according to claim 1 or 2, wherein the heat dissipation and temperature reduction modules (5) comprise a plurality of strong cold circulation units (52), each strong cold circulation unit (52) comprises a circulation pump (521), a cooling tank (522), a plurality of pipelines (523) arranged in a cable, and a temperature control mechanism (524) used for controlling the circulation pump (521), the circulation pump (521) and the temperature control mechanism (524) are arranged in the cooling tank (522), the circulation pump (521) is connected with two ends of the pipelines (523), and two ends of the pipelines (523) are provided with switch valve ports (525).

5. The 220 KV cable dynamic capacity increasing system according to claim 1 or 2, wherein the plurality of heat dissipation and temperature reduction modules (5) comprise a plurality of low-thermal-resistance filling units (51) filled in cable sections and a plurality of forced cooling circulation units (52).

6. The 220 kV cable dynamic capacity increasing system according to claim 5, wherein the forced cooling circulation unit (52) comprises a circulation pump (521), a cooling tank (522), a plurality of pipelines (523) arranged in the cable, and a temperature control mechanism (524) for controlling the circulation pump (521), the circulation pump (521) and the temperature control mechanism (524) are arranged in the cooling tank (522), the circulation pump (521) is connected with two ends of the pipelines (523), and two ends of the pipelines (523) are provided with switch valve ports (525).

7. A dynamic capacity increasing method for 220 KV cables, which is suitable for the dynamic capacity increasing system for 220 KV cables according to any one of claims 1-6, and is characterized by comprising the following steps:

s1: acquiring basic data, temperature data and current data of a cable;

s2: establishing a calculation model to calculate the real-time conductor temperature and the current-carrying capacity;

s3: the method is used for predicting the change condition of the temperature of the cable core wire when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time when a certain emergency load is loaded.

8. The dynamic capacity-increasing method for the 220 KV cable according to claim 7, wherein the step S2 comprises the following steps:

s21: establishing a calculation model to calculate the real-time conductor temperature and the full load flow;

s22: calculating the short-time current-carrying capacity by adopting a calculation formula defined in the IEC-60287 standard;

s23: and outputting the real-time conductor temperature value and each flow carrying quantity value.

9. The dynamic capacity increasing method for 220 KV cable according to claim 8, wherein the step of calculating real-time conductor temperature and current-carrying capacity in step S21 includes the steps of:

s211: according to a thermodynamic model of IEC-60287, combining the cable surface temperature monitored by the optical fiber temperature measuring module in real time and the cable load current monitored by the sheath current module in real time to obtain an adjusted conductor temperature rise calculation formula;

s212: and (4) reversely deducing real-time running current by the formula through the adjusted conductor temperature rise, namely the current full-load current-carrying capacity of the cable.

10. The dynamic capacity increasing method for 220 kv cable according to claim 9, wherein the formula for calculating the adjusted conductor temperature rise in step S211 is as follows:

θ_c＝θ_o+W_d[0.5T₁+n(T₂+T₃)]+I²RT₁+nI²R(1+λ₁)T₂+nI²R(1+λ₁+λ₁)T₃

in the formula, theta_cIs the conductor temperature, θ_oIs the skin temperature, W_dDielectric loss per unit length of conductor insulation, T₁Is the thermal resistance per unit length between the conductor and the metal sheath, T₂Is the thermal resistance per unit length of the inner liner between the metal sleeve and the armor, T₃The thermal resistance per unit length of the current outer sheath, λ₁Is the ratio of the cable sheath loss to the total loss of all conductors, λ₁The ratio of the cable sheathing loss to the total loss of all conductors is defined as n, the number of conductors carrying a load in the cable.

Technical Field

The invention relates to the technical field of cables, in particular to a 220 kV cable dynamic capacity increasing system and a method.

Background

At present, the central city area of a large-scale urban power grid has large power load and short cable channel resources, part of heavy-load lines become obvious transmission bottlenecks, the transmission potential of the existing cable is excavated through cable capacity increase, and the method has important significance for relieving urban power supply pressure.

At present, IEC60287, IEC853 and JB/T10181.3-2000 standards commonly adopted in cable ampacity calculation are aimed at steady-state calculation and are not suitable for calculating dynamic load. Moreover, the current carrying capacity of the cable is determined during the design phase, and due to the complexity and uncertainty of the heat transfer environment of the cable, designers often make the most unfavorable assumption of heat dissipation to obtain a sufficiently safe current value. This value will be used by the dispatch department throughout the cable life cycle. The problems of over-conservative value and large error of the current-carrying capacity of the cable are caused, and the power transmission capacity of the cable cannot be fully exerted.

At present, the technical means and related research of the dynamic capacity increase of the high-voltage cable line are not perfect, the practice and application cases of the dynamic capacity increase of the cable are few in China, and the method is applied to cities such as Shanghai, Guangzhou and the like. And correcting the current-carrying capacity calculation parameters of the cable according to the actually measured parameters of the region by taking the temperature of the conductor of the cable not exceeding the allowable temperature as a limiting condition, and predicting the short-term and long-term allowable current-carrying capacity of the cable line in real time. And the predicted current-carrying capacity is used as a capacity control value of the cable line, so that the dynamic capacity increase of the cable line is realized.

The other method is to improve the heat dissipation condition around the cable or add a forced cooling measure to reduce the operating temperature of the cable so as to improve the current-carrying capacity. The method mainly comprises the steps of filling a medium with a high heat conductivity coefficient in a calandria, filling a special cooling medium in an electric pipeline, laying a cooling pipeline outside a cable in parallel and the like, and only the first type has application.

The patent document in China discloses a quasi-dynamic capacity-increasing method based on a cable heat transfer model, and the publication number CN104330659B of the method comprises the following steps: 1) according to the working condition of the whole cable, a data acquisition system is established in the bottleneck cable section for carrying out data measurement on the same day; 2) according to the data of the bottleneck cable section measured by the data acquisition system on the same day, establishing and updating a cable heat transfer model of the bottleneck cable section on the next day by taking the day as a unit; 3) and estimating the current-carrying capacity of the cable to be subjected to capacity increase in the bottleneck cable section on the next day according to the cable heat transfer model of the bottleneck cable section on the next day, so as to realize the capacity increase of the cable. The disadvantages are as follows: the conductor temperature and the current-carrying capacity of the cable cannot be calculated in real time, and the heat dissipation condition around the cable is not improved or forced cooling measures are not added.

Disclosure of Invention

The invention mainly aims to solve the problems that the temperature and the current-carrying capacity of a cable conductor cannot be calculated in real time, and the heat dissipation condition around the cable is not improved or forced cooling measures are not added, and provides a 220 kV cable dynamic capacity increasing system and a method, which can calculate the temperature and the current-carrying capacity of the cable conductor in real time and have the functions of improving the heat dissipation condition around the cable or adding the forced cooling measures.

In order to achieve the purpose, the invention adopts the following technical scheme:

a 220 kv cable dynamic capacitance enhancement system, comprising:

the optical fiber temperature measuring modules are used for detecting the temperature of the outer surface of the cable and the ambient temperature;

the point volt grating modules are used for measuring the temperature of the cable at the pipe arranging opening;

the thermocouple modules are used for detecting the soil temperature;

the sheath current modules are used for collecting the real-time running current of the cable;

the plurality of heat dissipation and cooling modules are used for improving the heat dissipation conditions around the cable or increasing forced cooling measures;

and the diagnosis analysis module is used for calculating the conductor temperature and the current-carrying capacity in real time.

The optical fiber temperature measurement module is a temperature measurement optical fiber, the outer surface of the cable is subjected to temperature measurement in an optical fiber temperature measurement mode, and the two-loop cable line is wound with the temperature measurement optical fiber in a full-line mode. As the optical fiber in the calandria cannot be tightly attached to the surface of the cable, the cable at the calandria port is provided with the dot-shaped grating module for temperature measurement. The environment temperature adopts the mode of optical fiber temperature measurement and a thermocouple, the thermocouple module is buried in the soil of the pipe arrangement section for temperature measurement, and the temperature measurement optical fiber is laid on the wall of the cable trench, namely the optical fiber temperature measurement module.

The real-time load current of the power cable is another key factor for calculating the current-carrying capacity, the real-time current value in the cable conductor is obtained through the sheath current module, and the real-time calculation of the current-carrying capacity of the cable is carried out by combining the optical fiber temperature measurement module.

The diagnosis and analysis module calculates the real-time conductor temperature and the current-carrying capacity in a mode of establishing a calculation model, and predicts the change condition of the cable core wire temperature when the cable is loaded with any dynamic current-carrying capacity and the sustainable maximum time when a certain emergency load is loaded.

Preferably, the plurality of optical fiber temperature measuring modules, the plurality of point voltage grating modules, the plurality of thermocouple modules, the plurality of sheath current modules and the plurality of heat dissipation and cooling modules are all connected with the diagnosis and analysis module.

Through above-mentioned various detection module with heat dissipation cooling module with the diagnosis analysis module is connected, is convenient for the data that various modules were gathered are received to the diagnosis analysis module to through calculation analysis back, the prediction cable is when loading arbitrary dynamic current-carrying capacity the change condition of cable core wire temperature and load the sustainable longest time of a certain emergency load.

Preferably, the plurality of heat dissipation and temperature reduction modules comprise a plurality of low-thermal-resistance filling units filled in the cable duct sections.

And filling a low-thermal-resistance filling unit in the cable duct bank section with smaller current-carrying capacity, wherein the low-thermal-resistance filling unit is a low-thermal-resistance filling agent and is used for improving the heat dissipation condition and improving the current-carrying capacity. The cable pipe section is about 5 meters, the aperture of the calandria is large, the filling construction is easy to implement, the low-thermal-resistance filling agent is not solidified and hardened after filling, the service life of the material is more than 10 years, and the cleaning and the replacement are convenient after the material is invalid.

Preferably, the heat dissipation and cooling modules comprise a plurality of strong cooling circulation units, each strong cooling circulation unit comprises a circulation pump, a cooling tank, a plurality of pipelines arranged in the cable and a temperature control mechanism used for controlling the circulation pump, the circulation pump and the temperature control mechanism are arranged in the cooling tank, the circulation pump is connected with two ends of the pipelines, and two ends of the pipelines are provided with switch valve ports.

The pipelines are arranged in parallel at the top of each row pipe section, and can be arranged at the top of each row pipe section in parallel, so that the environmental temperature of the cables of the row pipe sections can be controlled conveniently. And judging whether each row pipe section exceeds a set temperature threshold value or not through the temperature control mechanism, starting the circulating pump through the temperature control mechanism if the row pipe section exceeds the temperature threshold value, circulating the cooling liquid in the cooling tank, reducing the environmental temperature of the cable through forced circulation, and improving the current-carrying capacity.

The switch valve port is used for controlling the circulation of cooling liquid, and the environmental temperature of cables of a plurality of row pipe sections can be controlled in a diversified mode. If a certain pipe section is in fault, the pipe section with the fault can be prevented from being fed by cooling liquid only by closing the switch valve port.

Preferably, the plurality of heat dissipation and temperature reduction modules comprise a plurality of low-thermal-resistance filling units filled in the cable duct sections and a plurality of strong cooling circulation units.

The heat dissipation and cooling module can be combined with the advantages of the low-thermal-resistance filling unit and the forced cooling circulation unit and arranged in the cable duct bank section, so that the heat dissipation condition around the cable can be effectively improved or the forced cooling is increased.

Preferably, the forced cooling circulation unit comprises a circulation pump, a cooling tank, a plurality of pipelines arranged in the cable and a temperature control mechanism for controlling the circulation pump, the circulation pump and the temperature control mechanism are arranged in the cooling tank, the circulation pump is connected with two ends of the pipelines, and two ends of the pipelines are provided with switch valve ports.

The pipelines are arranged in parallel at the top of each row pipe section, and can be arranged at the top of each row pipe section in parallel, so that the environmental temperature of the cables of the row pipe sections can be controlled conveniently. And judging whether each row pipe section exceeds a set temperature threshold value or not through the temperature control mechanism, starting the circulating pump through the temperature control mechanism if the row pipe section exceeds the temperature threshold value, circulating the cooling liquid in the cooling tank, reducing the environmental temperature of the cable through forced circulation, and improving the current-carrying capacity.

The switch valve port is used for controlling the circulation of cooling liquid, and the environmental temperature of cables of a plurality of row pipe sections can be controlled in a diversified mode. If a certain pipe section is in fault, the pipe section with the fault can be prevented from being fed by cooling liquid only by closing the switch valve port.

A dynamic capacity increasing method for a 220 kV cable comprises the following steps:

s1: acquiring basic data, temperature data and current data of a cable;

s2: establishing a calculation model to calculate the real-time conductor temperature and the current-carrying capacity;

s3: the method is used for predicting the change condition of the temperature of the cable core wire when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time when a certain emergency load is loaded.

The cable basic data comprises the dielectric loss of conductor insulation unit length, the thermal resistance of unit length between a conductor and a metal sleeve, the thermal resistance of unit length of an inner liner between the metal sleeve and an armor, the thermal resistance of unit length of a current outer protective layer, the ratio of the cable metal sleeve loss to the total loss of all conductors, the ratio of the cable armor loss to the total loss of all conductors and the like, and the real-time conductor temperature and the current-carrying capacity can be conveniently calculated by a subsequent calculation model.

The temperature data comprise the temperature of the outer surface of the cable and the ambient temperature detected by the optical fiber temperature measuring module, the temperature of the pipe arranging port cable measured by the point voltage grating module, the temperature of soil detected by the thermocouple module and the like, and the real-time conductor temperature and the current-carrying capacity can be conveniently calculated by a subsequent calculation model.

By the method, the conductor temperature and the current-carrying capacity of the cable can be calculated in real time, and the change condition of the cable core wire temperature when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time for loading a certain emergency load can be predicted.

Preferably, step S2 includes the steps of:

s21: establishing a calculation model to calculate the real-time conductor temperature and the full load flow;

s22: calculating the short-time current-carrying capacity by adopting a calculation formula defined in the IEC-60287 standard;

s23: and outputting the real-time conductor temperature value and each flow carrying quantity value.

Preferably, the step of calculating the real-time conductor temperature and the current carrying capacity in step S21 includes the following steps:

s211: according to a thermodynamic model of IEC-60287, combining the cable surface temperature monitored by the optical fiber temperature measuring module in real time and the cable load current monitored by the sheath current module in real time to obtain an adjusted conductor temperature rise calculation formula;

s212: and (4) reversely deducing real-time running current by the formula through the adjusted conductor temperature rise, namely the current full-load current-carrying capacity of the cable.

Preferably, the adjusted conductor temperature rise calculation formula in step S211 is as follows:

θ_c＝θ_o+W_d[0.5T₁+n(T₂+T₃)]+I²RT₁+nI²R(1+λ₁)T₂+nI²R(1+λ₁+λ₁)T₃

in the formula, theta_cIs the conductor temperature, θ_oIs the skin temperature, W_dDielectric loss per unit length of conductor insulation, T₁Is the thermal resistance per unit length between the conductor and the metal sheath, T₂Is the thermal resistance per unit length of the inner liner between the metal sleeve and the armor, T₃The thermal resistance per unit length of the current outer sheath, λ₁Is the ratio of the cable sheath loss to the total loss of all conductors, λ₁The ratio of the cable sheathing loss to the total loss of all conductors is defined as n, the number of conductors carrying a load in the cable.

The real-time running current formula is reversely deduced through the adjusted conductor temperature rise calculation formula, and the formula is as follows:

in the formula, T₄Is the thermal resistance per unit length between the cable surface and the surrounding medium.

The resulting value is the current 100% full capacity ampacity of the cable.

In step S22, the short-time ampacity is calculated by using a calculation formula defined in the IEC-60287 standard, where the calculation formula is specifically as follows:

wherein x is the cable preload coefficient, I_nFor rated current (calculated using full load ampacity), t is short time load run time, and τ is the wire thermal time constant.

The invention has the beneficial effects that:

(1) the device can improve the heat dissipation condition around the cable or increase the forced cooling measure.

(2) By the method, the conductor temperature and the current-carrying capacity are calculated in real time, and the change condition of the cable core wire temperature when the cable is loaded with any dynamic current-carrying capacity and the sustainable longest time for loading a certain emergency load are predicted.

Drawings

Fig. 1 is a schematic structural diagram of a first embodiment of the apparatus.

FIG. 2 is a schematic structural diagram of a second embodiment of the present device

FIG. 3 is a schematic structural diagram of a third embodiment of the present device

Fig. 4 is a schematic structural view of the forced cooling circulation unit.

FIG. 5 is a schematic flow diagram of the present method.

Illustration of the drawings: the system comprises a 1-optical fiber temperature measuring module, a 2-point voltage grating module, a 3-thermocouple module, a 4-sheath current module, a 5-heat dissipation and cooling module, a 6-diagnostic analysis module, a 51-low thermal resistance filling unit, a 52-strong cooling circulation unit, a 521-circulating pump, a 522-cooling box, a 523-pipeline, a 524-temperature control mechanism and a 525-switch valve port.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

The first embodiment is as follows:

as shown in fig. 1, a 220 kv cable dynamic capacity increasing system includes:

the optical fiber temperature measuring modules 1 are used for detecting the temperature of the outer surface of the cable and the ambient temperature;

the point-to-point grid modules 2 are used for measuring the temperature of the cable at the pipe arranging opening;

the thermocouple modules 3 are used for detecting the soil temperature;

the sheath current modules 4 are used for collecting the real-time running current of the cable;

the plurality of heat dissipation and cooling modules 5 are used for improving the heat dissipation conditions around the cable or adding forced cooling measures;

and the diagnostic analysis module 6 is used for calculating the conductor temperature and the current-carrying capacity in real time.

The optical fiber temperature measurement module is a temperature measurement optical fiber, the outer surface of the cable is subjected to temperature measurement in an optical fiber temperature measurement mode, and the two-circuit cable line is wound with the temperature measurement optical fiber in a full-line mode. As the optical fiber in the calandria cannot be tightly attached to the surface of the cable, the cable at the calandria port is provided with the dot-shaped grating module for temperature measurement. The environment temperature adopts the mode of optical fiber temperature measurement and thermocouple, the thermocouple module is buried in the soil of the calandria section for temperature measurement, and the temperature measurement optical fiber is laid on the cable trench wall, namely the optical fiber temperature measurement module.

The real-time load current of the power cable is another key factor for calculating the current-carrying capacity, the real-time current value in the cable conductor is obtained through the sheath current module, and the real-time calculation of the current-carrying capacity of the cable is carried out by combining the optical fiber temperature measuring module.

The diagnosis and analysis module calculates the real-time conductor temperature and the current-carrying capacity in a mode of establishing a calculation model, and predicts the change condition of the cable core wire temperature when the cable is loaded with any dynamic current-carrying capacity and the sustainable maximum time when a certain emergency load is loaded.

The plurality of optical fiber temperature measuring modules, the plurality of point voltage grating modules, the plurality of thermocouple modules, the plurality of sheath current modules and the plurality of heat dissipation and cooling modules are all connected with the diagnosis and analysis module.

The detection module and the heat dissipation and cooling module are connected with the diagnosis and analysis module, so that the diagnosis and analysis module can receive data acquired by the modules, and after calculation and analysis, the change condition of the temperature of the cable core wire when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time for loading a certain emergency load can be predicted.

The plurality of heat dissipation and temperature reduction modules comprise a plurality of low thermal resistance filling units 51 filled in the cable duct sections.

And a low-thermal-resistance filling unit is filled in the cable duct bank section with smaller current-carrying capacity, and the low-thermal-resistance filling unit is a low-thermal-resistance filling agent and is used for improving the heat dissipation condition and improving the current-carrying capacity. The cable pipe section is about 5 meters, the aperture of the calandria is large, the filling construction is easy to implement, the low-thermal-resistance filling agent is not solidified and hardened after filling, the service life of the material is more than 10 years, and the cleaning and the replacement are convenient after the material is invalid.

As shown in fig. 5, a dynamic capacity increasing method for a 220 kv cable includes the following steps:

s1: acquiring basic data, temperature data and current data of a cable;

s2: establishing a calculation model to calculate the real-time conductor temperature and the current-carrying capacity;

s3: the method is used for predicting the change condition of the temperature of the cable core wire when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time when a certain emergency load is loaded.

The basic data of the cable comprises the dielectric loss of the conductor insulation in unit length, the thermal resistance of the conductor and the metal sleeve in unit length, the thermal resistance of the inner liner between the metal sleeve and the armor in unit length, the thermal resistance of the current outer protective layer in unit length, the ratio of the cable metal sleeve loss to the total loss of all conductors, the ratio of the cable armor loss to the total loss of all conductors and the like, and the real-time conductor temperature and the current-carrying capacity can be conveniently calculated by a subsequent calculation model.

The temperature data comprise the temperature of the outer surface of the cable and the ambient temperature detected by the optical fiber temperature measuring module, the temperature of the cable at the pipe discharging port measured by the point voltage grating module, the temperature of soil detected by the thermocouple module and the like, and the real-time conductor temperature and the current-carrying capacity can be conveniently calculated by a subsequent calculation model.

By the method, the conductor temperature and the current-carrying capacity of the cable can be calculated in real time, and the change condition of the cable core wire temperature when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time for loading a certain emergency load can be predicted.

Step S2 includes the following steps:

s21: establishing a calculation model to calculate the real-time conductor temperature and the full load flow;

s22: calculating the short-time current-carrying capacity by adopting a calculation formula defined in the IEC-60287 standard;

s23: and outputting the real-time conductor temperature value and each flow carrying quantity value.

Calculating the real-time conductor temperature and the current capacity in the step S21 includes the following steps:

s211: according to a thermodynamic model of IEC-60287, combining the cable surface temperature monitored by the optical fiber temperature measuring module in real time and the cable load current monitored by the sheath current module in real time to obtain an adjusted conductor temperature rise calculation formula;

s212: and (4) reversely deducing real-time running current by the formula through the adjusted conductor temperature rise, namely the current full-load current-carrying capacity of the cable.

The calculation formula of the adjusted conductor temperature rise in step S211 is as follows:

θ_c＝θ_o+W_d[0.5T₁+n(T₂+T₃)]+I²RT₁+nI²R(1+λ₁)T₂+nI²R(1+λ₁+λ₁)T₃

in the formula, theta_cIs the conductor temperature, θ_oIs the skin temperature, W_dDielectric loss per unit length of conductor insulation, T₁Is the thermal resistance per unit length between the conductor and the metal sheath, T₂Is the thermal resistance per unit length of the inner liner between the metal sleeve and the armor, T₃The thermal resistance per unit length of the current outer sheath, λ₁For cable metal sheath losses relative to total losses of all conductorsRatio of (A) to (B)₁The ratio of the cable sheathing loss to the total loss of all conductors is defined as n, the number of conductors carrying a load in the cable.

The real-time running current formula is reversely deduced through the adjusted conductor temperature rise calculation formula, and the formula is specifically as follows:

in the formula, T₄Is the thermal resistance per unit length between the cable surface and the surrounding medium.

The resulting value is the current 100% full capacity ampacity of the cable.

In step S22, a calculation formula defined in the IEC-60287 standard is used to calculate the short-term ampacity, and the calculation formula is specifically as follows:

wherein x is the cable preload coefficient, I_nFor rated current (calculated using full load ampacity), t is short time load run time, and τ is the wire thermal time constant.

Example two:

as shown in fig. 2 and 4, a 220 kv cable dynamic capacity increasing system includes:

the optical fiber temperature measuring modules 1 are used for detecting the temperature of the outer surface of the cable and the ambient temperature;

the point-to-point grid modules 2 are used for measuring the temperature of the cable at the pipe arranging opening;

the thermocouple modules 3 are used for detecting the soil temperature;

the sheath current modules 4 are used for collecting the real-time running current of the cable;

the plurality of heat dissipation and cooling modules 5 are used for improving the heat dissipation conditions around the cable or adding forced cooling measures;

and the diagnostic analysis module 6 is used for calculating the conductor temperature and the current-carrying capacity in real time.

The optical fiber temperature measurement module is a temperature measurement optical fiber, the outer surface of the cable is subjected to temperature measurement in an optical fiber temperature measurement mode, and the two-circuit cable line is wound with the temperature measurement optical fiber in a full-line mode. As the optical fiber in the calandria cannot be tightly attached to the surface of the cable, the cable at the calandria port is provided with the dot-shaped grating module for temperature measurement. The environment temperature adopts the mode of optical fiber temperature measurement and thermocouple, the thermocouple module is buried in the soil of the calandria section for temperature measurement, and the temperature measurement optical fiber is laid on the cable trench wall, namely the optical fiber temperature measurement module.

The real-time load current of the power cable is another key factor for calculating the current-carrying capacity, the real-time current value in the cable conductor is obtained through the sheath current module, and the real-time calculation of the current-carrying capacity of the cable is carried out by combining the optical fiber temperature measuring module.

The diagnosis and analysis module calculates the real-time conductor temperature and the current-carrying capacity in a mode of establishing a calculation model, and predicts the change condition of the cable core wire temperature when the cable is loaded with any dynamic current-carrying capacity and the sustainable maximum time when a certain emergency load is loaded.

The plurality of optical fiber temperature measuring modules, the plurality of point voltage grating modules, the plurality of thermocouple modules, the plurality of sheath current modules and the plurality of heat dissipation and cooling modules are all connected with the diagnosis and analysis module.

The detection module and the heat dissipation and cooling module are connected with the diagnosis and analysis module, so that the diagnosis and analysis module can receive data acquired by the modules, and after calculation and analysis, the change condition of the temperature of the cable core wire when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time for loading a certain emergency load can be predicted.

The plurality of heat dissipation and cooling modules comprise a plurality of forced cooling circulation units 52, each forced cooling circulation unit comprises a circulation pump 521, a cooling box 522, a plurality of pipelines 523 arranged in a cable and a temperature control mechanism 524 used for controlling the circulation pump, the circulation pump and the temperature control mechanism are arranged in the cooling box, the circulation pump is connected with the two ends of the pipelines, and the two ends of each pipeline are provided with a switch valve port 525.

The pipeline is arranged in parallel at the top of each row pipe section, and the pipeline can be arranged in parallel at the top of each row pipe section, so that the environmental temperature of the cables of the row pipe sections can be controlled conveniently. Whether each row pipe section exceeds a set temperature threshold value is judged through the temperature control mechanism, if the temperature control mechanism starts the circulating pump when the temperature threshold value is exceeded, the cooling liquid in the cooling box circulates, the environmental temperature of the cable is reduced through forced circulation, and the carrying capacity is improved.

The switch valve port is used for controlling the circulation of cooling liquid, and the environmental temperature of cables of a plurality of row pipe sections can be controlled in a diversified mode. If a certain pipe section is in fault, the pipe section with the fault can be prevented from being fed by cooling liquid only by closing the switch valve port.

As shown in fig. 5, a dynamic capacity increasing method for a 220 kv cable includes the following steps:

s1: acquiring basic data, temperature data and current data of a cable;

s2: establishing a calculation model to calculate the real-time conductor temperature and the current-carrying capacity;

s3: the method is used for predicting the change condition of the temperature of the cable core wire when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time when a certain emergency load is loaded.

The basic data of the cable comprises the dielectric loss of the conductor insulation in unit length, the thermal resistance of the conductor and the metal sleeve in unit length, the thermal resistance of the inner liner between the metal sleeve and the armor in unit length, the thermal resistance of the current outer protective layer in unit length, the ratio of the cable metal sleeve loss to the total loss of all conductors, the ratio of the cable armor loss to the total loss of all conductors and the like, and the real-time conductor temperature and the current-carrying capacity can be conveniently calculated by a subsequent calculation model.

The temperature data comprise the temperature of the outer surface of the cable and the ambient temperature detected by the optical fiber temperature measuring module, the temperature of the cable at the pipe discharging port measured by the point voltage grating module, the temperature of soil detected by the thermocouple module and the like, and the real-time conductor temperature and the current-carrying capacity can be conveniently calculated by a subsequent calculation model.

By the method, the conductor temperature and the current-carrying capacity of the cable can be calculated in real time, and the change condition of the cable core wire temperature when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time for loading a certain emergency load can be predicted.

Step S2 includes the following steps:

s21: establishing a calculation model to calculate the real-time conductor temperature and the full load flow;

s22: calculating the short-time current-carrying capacity by adopting a calculation formula defined in the IEC-60287 standard;

s23: and outputting the real-time conductor temperature value and each flow carrying quantity value.

Calculating the real-time conductor temperature and the current capacity in the step S21 includes the following steps:

s211: according to a thermodynamic model of IEC-60287, combining the cable surface temperature monitored by the optical fiber temperature measuring module in real time and the cable load current monitored by the sheath current module in real time to obtain an adjusted conductor temperature rise calculation formula;

s212: and (4) reversely deducing real-time running current by the formula through the adjusted conductor temperature rise, namely the current full-load current-carrying capacity of the cable.

The calculation formula of the adjusted conductor temperature rise in step S211 is as follows:

θ_c＝θ_o+W_d[0.5T₁+n(T₂+T₃)]+I²RT₁+nI²R(1+λ₁)T₂+nI²R(1+λ₁+λ₁)T₃

in the formula, theta_cIs the conductor temperature, θ_oIs the skin temperature, W_dDielectric loss per unit length of conductor insulation, T₁Is the thermal resistance per unit length between the conductor and the metal sheath, T₂Is the thermal resistance per unit length of the inner liner between the metal sleeve and the armor, T₃The thermal resistance per unit length of the current outer sheath, λ₁Is the ratio of the cable sheath loss to the total loss of all conductors, λ₁The ratio of the cable sheathing loss to the total loss of all conductors is defined as n, the number of conductors carrying a load in the cable.

The real-time running current formula is reversely deduced through the adjusted conductor temperature rise calculation formula, and the formula is specifically as follows:

in the formula, T₄Is the thermal resistance per unit length between the cable surface and the surrounding medium.

The resulting value is the current 100% full capacity ampacity of the cable.

In step S22, a calculation formula defined in the IEC-60287 standard is used to calculate the short-term ampacity, and the calculation formula is specifically as follows:

wherein x is the cable preload coefficient, I_nFor rated current (calculated using full load ampacity), t is short time load run time, and τ is the wire thermal time constant.

Example three:

as shown in fig. 3 and 4, a 220 kv cable dynamic capacity increasing system includes:

the optical fiber temperature measuring modules 1 are used for detecting the temperature of the outer surface of the cable and the ambient temperature;

the point-to-point grid modules 2 are used for measuring the temperature of the cable at the pipe arranging opening;

the thermocouple modules 3 are used for detecting the soil temperature;

the sheath current modules 4 are used for collecting the real-time running current of the cable;

the plurality of heat dissipation and cooling modules 5 are used for improving the heat dissipation conditions around the cable or adding forced cooling measures;

and the diagnostic analysis module 6 is used for calculating the conductor temperature and the current-carrying capacity in real time.

The optical fiber temperature measurement module is a temperature measurement optical fiber, the outer surface of the cable is subjected to temperature measurement in an optical fiber temperature measurement mode, and the two-circuit cable line is wound with the temperature measurement optical fiber in a full-line mode. As the optical fiber in the calandria cannot be tightly attached to the surface of the cable, the cable at the calandria port is provided with the dot-shaped grating module for temperature measurement. The environment temperature adopts the mode of optical fiber temperature measurement and thermocouple, the thermocouple module is buried in the soil of the calandria section for temperature measurement, and the temperature measurement optical fiber is laid on the cable trench wall, namely the optical fiber temperature measurement module.

The real-time load current of the power cable is another key factor for calculating the current-carrying capacity, the real-time current value in the cable conductor is obtained through the sheath current module, and the real-time calculation of the current-carrying capacity of the cable is carried out by combining the optical fiber temperature measuring module.

The diagnosis and analysis module calculates the real-time conductor temperature and the current-carrying capacity in a mode of establishing a calculation model, and predicts the change condition of the cable core wire temperature when the cable is loaded with any dynamic current-carrying capacity and the sustainable maximum time when a certain emergency load is loaded.

The plurality of optical fiber temperature measuring modules, the plurality of point voltage grating modules, the plurality of thermocouple modules, the plurality of sheath current modules and the plurality of heat dissipation and cooling modules are all connected with the diagnosis and analysis module.

The detection module and the heat dissipation and cooling module are connected with the diagnosis and analysis module, so that the diagnosis and analysis module can receive data acquired by the modules, and after calculation and analysis, the change condition of the temperature of the cable core wire when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time for loading a certain emergency load can be predicted.

The plurality of heat dissipation and cooling modules comprise a plurality of low-thermal resistance filling units 51 filled in the cable row pipe sections and a plurality of forced cooling circulation units 52, each forced cooling circulation unit comprises a circulation pump 521, a cooling tank 522, a plurality of pipelines 523 arranged in the cable and a temperature control mechanism 524 used for controlling the circulation pump, the circulation pump and the temperature control mechanism are arranged in the cooling tank, the circulation pumps are connected with the two ends of the pipelines, and the two ends of the pipelines are both provided with switch valve ports 525.

And a low-thermal-resistance filling unit is filled in the cable duct bank section with smaller current-carrying capacity, and the low-thermal-resistance filling unit is a low-thermal-resistance filling agent and is used for improving the heat dissipation condition and improving the current-carrying capacity. The cable pipe section is about 5 meters, the aperture of the calandria is large, the filling construction is easy to implement, the low-thermal-resistance filling agent is not solidified and hardened after filling, the service life of the material is more than 10 years, and the cleaning and the replacement are convenient after the material is invalid.

The pipeline is arranged in parallel at the top of each row pipe section, and the pipeline can be arranged in parallel at the top of each row pipe section, so that the environmental temperature of the cables of the row pipe sections can be controlled conveniently. Whether each row pipe section exceeds a set temperature threshold value is judged through the temperature control mechanism, if the temperature control mechanism starts the circulating pump when the temperature threshold value is exceeded, the cooling liquid in the cooling box circulates, the environmental temperature of the cable is reduced through forced circulation, and the carrying capacity is improved.

The switch valve port is used for controlling the circulation of cooling liquid, and the environmental temperature of cables of a plurality of row pipe sections can be controlled in a diversified mode. If a certain pipe section is in fault, the pipe section with the fault can be prevented from being fed by cooling liquid only by closing the switch valve port.

The heat dissipation and cooling module can be combined with the advantages of the low-thermal-resistance filling unit and the forced cooling circulation unit and arranged in the cable duct bank section, so that the heat dissipation condition around the cable can be effectively improved or the forced cooling is increased.

As shown in fig. 5, a dynamic capacity increasing method for a 220 kv cable includes the following steps:

s1: acquiring basic data, temperature data and current data of a cable;

s2: establishing a calculation model to calculate the real-time conductor temperature and the current-carrying capacity;

s3: the method is used for predicting the change condition of the temperature of the cable core wire when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time when a certain emergency load is loaded.

The basic data of the cable comprises the dielectric loss of the conductor insulation in unit length, the thermal resistance of the conductor and the metal sleeve in unit length, the thermal resistance of the inner liner between the metal sleeve and the armor in unit length, the thermal resistance of the current outer protective layer in unit length, the ratio of the cable metal sleeve loss to the total loss of all conductors, the ratio of the cable armor loss to the total loss of all conductors and the like, and the real-time conductor temperature and the current-carrying capacity can be conveniently calculated by a subsequent calculation model.

The temperature data comprise the temperature of the outer surface of the cable and the ambient temperature detected by the optical fiber temperature measuring module, the temperature of the cable at the pipe discharging port measured by the point voltage grating module, the temperature of soil detected by the thermocouple module and the like, and the real-time conductor temperature and the current-carrying capacity can be conveniently calculated by a subsequent calculation model.

By the method, the conductor temperature and the current-carrying capacity of the cable can be calculated in real time, and the change condition of the cable core wire temperature when the cable is loaded with any dynamic current-carrying capacity and the longest sustainable time for loading a certain emergency load can be predicted.

Step S2 includes the following steps:

s21: establishing a calculation model to calculate the real-time conductor temperature and the full load flow;

s22: calculating the short-time current-carrying capacity by adopting a calculation formula defined in the IEC-60287 standard;

s23: and outputting the real-time conductor temperature value and each flow carrying quantity value.

Calculating the real-time conductor temperature and the current capacity in the step S21 includes the following steps:

s211: according to a thermodynamic model of IEC-60287, combining the cable surface temperature monitored by the optical fiber temperature measuring module in real time and the cable load current monitored by the sheath current module in real time to obtain an adjusted conductor temperature rise calculation formula;

s212: and (4) reversely deducing real-time running current by the formula through the adjusted conductor temperature rise, namely the current full-load current-carrying capacity of the cable.

The calculation formula of the adjusted conductor temperature rise in step S211 is as follows:

θ_c＝θ_o+W_d[0.5T₁+n(T₂+T₃)]+I²RT₁+nI²R(1+λ₁)T₂+nI²R(1+λ₁+λ₁)T₃

in the formula, theta_cIs the conductor temperature, θ_oIs the skin temperature, W_dDielectric loss per unit length of conductor insulation, T₁Is the thermal resistance per unit length between the conductor and the metal sheath, T₂Is the thermal resistance per unit length of the inner liner between the metal sleeve and the armor, T₃The thermal resistance per unit length of the current outer sheath, λ₁Is the ratio of the cable sheath loss to the total loss of all conductors, λ₁The ratio of the cable sheathing loss to the total loss of all conductors is defined as n, the number of conductors carrying a load in the cable.

The real-time running current formula is reversely deduced through the adjusted conductor temperature rise calculation formula, and the formula is specifically as follows:

in the formula, T₄Is the thermal resistance per unit length between the cable surface and the surrounding medium.

The resulting value is the current 100% full capacity ampacity of the cable.

In step S22, a calculation formula defined in the IEC-60287 standard is used to calculate the short-term ampacity, and the calculation formula is specifically as follows:

wherein x is the cable preload coefficient, I_nFor rated current (calculated using full load ampacity), t is short time load run time, and τ is the wire thermal time constant.

It should be understood that this example is only for illustrating the present invention and is not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.