CN119199641B - A live monitoring system and device for detecting the health status of cables in operation - Google Patents
A live monitoring system and device for detecting the health status of cables in operation Download PDFInfo
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- CN119199641B CN119199641B CN202411714219.8A CN202411714219A CN119199641B CN 119199641 B CN119199641 B CN 119199641B CN 202411714219 A CN202411714219 A CN 202411714219A CN 119199641 B CN119199641 B CN 119199641B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/145—Indicating the presence of current or voltage
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/58—Testing of lines, cables or conductors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
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- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The invention belongs to the technical field of cable health state assessment, and particularly relates to a live monitoring system and device for detecting the health condition of an in-process cable, wherein the system comprises a potential difference determining module, a live detection module, a leakage current acquisition module, an insulation voltage acquisition module, a health assessment module and a scoring output alarm module; the device comprises a single-phase switch, a current transformer, a high-precision voltage transmitter, a processor and a memory. According to the invention, the maintenance frequency and the maintenance depth can be dynamically adjusted according to the score, thereby realizing lean management, providing a more flexible early warning mechanism, enabling the cable maintenance to have more pertinence and flexibility, further greatly reducing the unnecessary maintenance times, and effectively solving the problem of wasting calculation power caused by too frequent occurrence of unnecessary maintenance in the prior art.
Description
Technical Field
The invention belongs to the technical field of cable health state evaluation, and particularly relates to an electrified monitoring system and device for detecting the health state of an in-process cable.
Background
As the complexity of modern power systems increases, the dependence of the delivery and distribution of power on the cables also becomes more pronounced. Especially in the context of the acceleration of the urban process and the continuous increase of the power demand, the power system is faced with higher operating requirements. As a core part of power transmission, cables are required to carry not only a large number of power transmission tasks, but also to stably operate in a complex and severe environment. Thus, ensuring the health of cables is a critical aspect in the management of electrical systems.
At present, the cable monitoring technology mainly comprises the following two common methods, namely, the comprehensive evaluation of the multilevel health state of the cable is realized by simultaneously monitoring the running state of a cable grounding system and the insulation structure condition of a cable body. By arranging the measuring electrode outside the cable insulating layer, the cable defect is accurately positioned, so that the insulating health condition of the high-voltage alternating-current cable is monitored in real time, and potential defects or faults are found in time.
However, in the implementation process of the existing cable monitoring technology, a single threshold method or a direct maintenance method based on defect positioning is adopted to realize monitoring, so that the problem of wasting calculation force caused by too frequent occurrence of unnecessary maintenance exists.
Disclosure of Invention
According to the defects of the prior art, the invention aims to provide a live monitoring system and a live monitoring device for detecting the health condition of an on-line cable, which can dynamically adjust the maintenance frequency and the maintenance depth according to the score, and realize lean management.
The invention provides an electrified monitoring system for detecting the health condition of an on-line cable, which comprises a potential difference determining module, an electrified detecting module, a leakage current collecting module, an insulation voltage collecting module, a health evaluating module and a scoring output alarm module, wherein the potential difference determining module is used for determining the potential difference of the on-line cable;
The potential difference determining module is used for acquiring the potential difference between the steel armoured grounding lead of the 10kV cable terminal and the cabinet body, judging whether to acquire the current value and the voltage value of the grounding lead under the electrified condition according to the potential difference, if the potential difference is zero, continuing to acquire the current value and the voltage value under the electrified condition through the electrified detecting module, and if the potential difference is not zero, directly giving out a warning;
the live detection module is used for starting the leakage current acquisition module and the insulation voltage acquisition module based on bypass operation when the potential difference is zero;
The leakage current acquisition module is used for acquiring leakage current signals and analyzing leakage current indexes according to the leakage current signals, wherein the leakage current indexes are used for evaluating the current insulation state of the cable;
The insulation voltage acquisition module is used for disconnecting the grounding lead and acquiring a voltage signal of the cable terminal through a voltage acquisition technology in an electrified mode, analyzing an insulation voltage index based on the acquired voltage signal, wherein the insulation voltage index is used for evaluating the insulation state of the cable voltage;
The health evaluation module is used for acquiring the leakage current index and the insulation voltage index, analyzing the health condition index according to the leakage current index and the insulation voltage index, and evaluating the health condition of the in-transit cable;
And the scoring output alarm module is used for outputting the score of the current cable according to the scoring rule according to the health condition index and automatically alarming according to the score.
Preferably, the 10kV cable terminal steel armor grounding lead is insulated and isolated from the cabinet body by adopting a half lap wrapping insulation coating method, wherein the withstand voltage of the insulation coating is 1000V.
Preferably, the bypass operation includes connecting a single-phase switch with 32A current capacity in series in the ground braid loop.
Preferably, the acquisition method of the leakage current signal comprises a parallel shunt mode and a series current transformer mode;
The parallel shunt mode is connected with the grounding braid in parallel and collects current signals in a shunt mode;
the serial current transformer mode refers to the collection of signals through serial current transformers;
The acquisition precision of the parallel shunt mode and the series current transformer mode both reach the mu A level.
Preferably, the step of obtaining the leakage current index includes:
acquiring the current environmental humidity value of the cable, the current environmental temperature value of the cable and the leakage current value at the current time t, preprocessing, and normalizing the preprocessed current environmental humidity value of the cable, the current environmental temperature value of the cable and the leakage current value at the current time t;
acquiring a preset safe current threshold value from a database;
acquiring the weight of the current environmental humidity value of the cable on the leakage current index, the weight of the current environmental temperature value of the cable on the leakage current index and the weight of the ratio of the leakage current value at the current time t to a preset safety current threshold value on the leakage current index by an objective weighting method;
obtaining a leakage current index through a leakage current index calculation formula:
;
wherein XLI is leakage current index, e is natural constant, pi is circumference rate, H is current environmental humidity value of cable, For the weight of H to XLI, T is the current ambient temperature value of the cable,For the weight of T for XLI,As the leakage current value at the present time t,For a preset safety current threshold value,Is thatAnd (3) withIs the ratio of (1) to XLI.
Preferably, the specific obtaining step of the insulation voltage index is as follows:
Acquiring an insulation resistance value of the cable, a leakage current value at the current time t and an actual voltage signal value at the current time t, preprocessing, and normalizing the insulation resistance value of the preprocessed cable, the leakage current value at the current time t and the actual voltage signal value at the current time t;
Acquiring a preset standard voltage value from a database;
The method comprises the steps of obtaining the weight of an insulation resistance value of a cable to an insulation voltage index, the weight of a leakage current value at the current time t to the insulation voltage index and the weight of the ratio of an actual voltage signal value at the current time t to a preset standard voltage value to the insulation voltage index through an objective weighting method;
obtaining an insulation voltage index through an insulation voltage index calculation formula:
;
wherein JYI is an insulation voltage index, e is a natural constant, R is an insulation resistance value of the cable, For the weight of R to JYI,As the leakage current value at the present time t,Is thatWith respect to the weights of JYI,For the actual voltage signal value at the present time t,For a preset value of the standard voltage to be reached,Is thatAnd (3) withFor a weight of JYI.
Preferably, the step of obtaining the health condition index comprises the following steps:
Acquiring leakage current index and insulation voltage index at the same time t;
acquiring weights of leakage current indexes and insulation voltage indexes on health condition indexes respectively by an objective weighting method;
And obtaining the health condition index through a health condition index calculation formula.
Preferably, the health condition index calculation formula is:
;
Wherein JKI is a health index, pi is a circumference ratio, XLI is a leakage current index, JYI is an insulation voltage index, For the weight of XLI to JKI,Is JYI for JKI.
Preferably, the step of outputting the score of the current cable according to the scoring rule and automatically alarming according to the score specifically refers to:
When the health state index score of the cable is less than 50, triggering an alarm and suggesting that the power failure overhauls the cable;
When the health state index score of the cable is more than or equal to 50 and less than 80, carrying out live partial discharge and infrared detection for 1 time per week;
when the health state index score of the cable is greater than or equal to 80, outputting that the cable is in a relatively healthy state.
An electrified monitoring device for detecting the health condition of an on-line cable, which is used for realizing the system, and comprises:
the single-phase switch is used for being connected with the ground braid loop in series;
the current transformer is used for collecting current signals through the serial connection braids;
The high-precision voltage transmitter is used for acquiring voltage signals in a grounding lead disconnection mode;
the system comprises a processor and a memory, wherein computer program instructions are stored in the memory, and when the processor is configured to execute the computer program instructions, the single-phase switch, the current transformer and the high-precision voltage transmitter are caused to execute setting actions.
The invention has the following beneficial effects:
according to the invention, the maintenance frequency and the maintenance depth can be dynamically adjusted according to the score, thereby realizing lean management, providing a more flexible early warning mechanism, enabling the cable maintenance to have more pertinence and flexibility, further greatly reducing the unnecessary maintenance times, and effectively solving the problem of wasting calculation power caused by too frequent occurrence of unnecessary maintenance in the prior art.
According to the invention, the voltage signal of the cable terminal is obtained through the voltage acquisition technology, and the calculated insulation voltage index is combined, so that the comprehensive evaluation of the insulation state of the cable can be provided, the monitoring precision is improved, the insulation problem possibly existing in the cable can be found in advance, and the safe operation of the power system is ensured.
According to the invention, the leakage current acquisition module can provide high-precision data through two acquisition modes of a parallel shunt mode and a series current transformer mode, and an effective evaluation is provided for the insulation state of the cable through the leakage current index, so that the stable and safe operation of the power system is ensured.
Drawings
FIG. 1 is a schematic block diagram of the system of the present invention.
Detailed Description
The following describes the above technical scheme in detail with reference to the drawings and specific embodiments.
Embodiment 1 As shown in fig. 1, the live monitoring system for detecting the health condition of the cable comprises a potential difference determining module, a live detecting module, a leakage current collecting module, an insulation voltage collecting module, a health evaluating module and a scoring output alarm module.
The potential difference determining module is used for acquiring the potential difference between the steel armor grounding lead of the 10kV cable terminal and the cabinet body, judging whether to acquire the current value and the voltage value of the grounding lead under the electrified condition according to the potential difference, if the potential difference is zero, continuing to acquire the current value and the voltage value under the electrified condition through the electrified detecting module, and if the potential difference is not zero, directly giving out a warning. And at the position of the 10kV cable terminal steel armor grounding lead, insulating and isolating the grounding lead from the cabinet body by adopting a half lap wrapping insulating and coating method, wherein the withstand voltage of the insulating and coating method is 1000V.
Under the electrified condition, if the potential difference is zero, the potential between the grounding lead and the cabinet body is equal, the system continues to work at the moment, current and voltage signals are collected through the electrified detection module, and if the potential difference is not zero, an alarm is immediately sent out to prompt that the grounding problem or the system fault possibly exists. Through the current and voltage data acquisition under the electrified state, the running state and the insulation performance of the cable can be accurately monitored, and the cable is ensured not to be damaged or abnormal under the normal working condition. The insulating coating technology of the semi-lap-wrapping is adopted to insulate the grounding lead, so that the insulating safety and the compressive capacity of the grounding lead are improved, and particularly in a high-voltage system, the phenomenon of electric leakage or breakdown possibly caused by overhigh voltage is avoided, the safety of the system is improved, and the running stability of the system and the service life of electric equipment are also improved.
The insulating coating method is to cover the surface of the conductive material with insulating material to isolate current and prevent current leakage or electric fault. Withstand voltage refers to the maximum voltage value that a material or component can withstand without breakdown or damage. The withstand voltage of the insulating coating material is 1000V, which means that the insulating layer can withstand a voltage of up to 1000V, and electrical isolation safety can be ensured.
And the live detection module is used for starting the leakage current acquisition module and the insulation voltage acquisition module based on bypass operation when the potential difference is zero so as to monitor the insulation performance and the current leakage condition of the cable system in real time. The bypass operation includes connecting a single-phase switch with 32A current capacity in series in the ground strap loop.
Bypass operation is a mode of operation that does not interfere with normal power supply, typically by installing additional switches or loops, allowing detection, monitoring or maintenance to be performed without power outage. Through bypass operation mode, need not cut off the current supply of cable, just can carry out electrified monitoring, avoid influencing the normal operating of cable. Bypass operation allows for safe collection of current and voltage signals during normal operation of the power system by connecting a single phase switch with 32A current capacity in series in the ground braid loop. The mode does not influence the flow of electric power, and can ensure the continuity of an electric power system.
Through bypass operation, can carry out effectual live monitoring and need not have a power failure, furthest reduce power system's outage time, ensure power supply's persistence. The bypass switch can also realize flexible control, is convenient and safe to operate, and avoids potential safety hazards caused by power-off operation. Through the live detection module and the potential difference determining module, high-precision and real-time assessment of insulation performance is guaranteed to be realized under the live condition, and then comprehensive health indexes and a grading alarm mechanism are generated, so that complete monitoring and management are provided for the health state of the cable.
A 32A single-phase switch is an electrical switch with a current carrying capacity of 32 amperes, which is used for controlling the current flow direction and is suitable for a single-phase circuit. In addition, the single-phase switch of 32A has higher current-passing capability, can support high-load current, and ensures the accuracy and stability of current collection by controlling the current flow direction. Meanwhile, the high safety of the switch can be ensured, and overload, short circuit or other faults under the electrified condition are avoided.
The ground braid loop is the current path connecting the cable termination, the ground lead and the ground grounding system. In the power system, the grounding braid loop is used for ensuring that fault current is smoothly led into the ground through the ground wire, so that the safety of equipment is ensured. A switch in the bypass operation is installed in the loop to control the flow direction of the current and monitor it.
The leakage current acquisition module is used for acquiring leakage current signals and analyzing leakage current indexes according to the leakage current signals, wherein the leakage current indexes are used for evaluating the current insulation state of the cable, helping to monitor whether the cable has leakage current abnormality or not, ensuring the safe operation of the power system, helping to find potential insulation faults or ageing problems in time and reducing the potential safety hazards of the power system. In addition, the monitoring mode of the module is a non-invasive mode, and the normal operation of the power system is not affected.
The acquisition method of the leakage current signal comprises a parallel shunt mode and a serial current transformer mode, wherein the parallel shunt mode is connected with the grounding braid in parallel and acquires the current signal in a shunt mode, the serial current transformer mode is used for acquiring the signal through the serial current transformer, and the acquisition precision of the parallel shunt mode and the serial current transformer mode both reach the mu A level.
In the parallel shunt mode, the acquisition mode of the leakage current signal is that the measurement equipment is connected with the grounding braid in parallel, and the current signal is acquired in a shunt mode, so that the current leakage value can be accurately measured under the condition of not interrupting current, the acquisition of the current signal is ensured not to cause interference to a power system, and the parallel shunt mode is particularly suitable for monitoring a high-voltage or high-current system. Meanwhile, current signals are acquired in a shunt mode, so that the current leakage quantity can be acquired more accurately, and data with higher accuracy are provided for evaluating the insulation health state of the cable.
The series current transformer mode monitors current by connecting a current transformer in series in a cable loop. The series current transformer mode measures leakage current signals by concatenating current transformers in a cable loop. A current transformer is a device for current measurement that is capable of converting a high current into a low current or voltage for reading by a measurement device. The current transformer can accurately capture the leakage current passing through the cable, particularly has excellent precision and stability in a high-voltage system, can directly measure the leakage current passing through the cable, can effectively distinguish the tiny leakage current of the cable, and has extremely high measurement precision.
The accuracy of the μa level means that the current collection device is able to measure currents on the microampere level with an accuracy of 1 μa (parts per million amperes). The accuracy of the acquisition at the μa level ensures accurate measurement of leakage current so that even small leakage current variations can be captured by the detection system. Therefore, the system can discover potential cable damage or insulation problems as early as possible, provides key data for later maintenance and repair, and prevents large power faults.
The leakage current index obtaining method comprises the steps of obtaining the current environment humidity value of the cable, the current environment temperature value of the cable and the leakage current value at the current time t, preprocessing, normalizing the preprocessed current environment humidity value of the cable, the current environment temperature value of the cable and the leakage current value at the current time t, removing the data unit dimension, obtaining a preset safety current threshold value from a database, obtaining the weight of the current environment humidity value of the cable to the leakage current index, the weight of the current environment temperature value of the cable to the leakage current index and the weight of the ratio of the leakage current value at the current time t to the preset safety current threshold value to the leakage current index through an objective weighting method, and obtaining the leakage current index through a leakage current index calculation formula:
;
wherein XLI is leakage current index, e is natural constant, pi is circumference rate, H is current environmental humidity value of cable, For the weight of H to XLI, T is the current ambient temperature value of the cable,For the weight of T for XLI,As the leakage current value at the present time t,For a preset safety current threshold value,Is thatAnd (3) withIs the ratio of (1) to XLI.
A specific example is the current environmental humidity value h=0.8 of the cable,=0.3, The current ambient temperature value t=30 degrees celsius of the cable,=0.3 Leakage current value at present time t=40 MA/km, preset safety current threshold=63mA/km,Xli=0.619 calculated as xli=0.4. The higher the leakage current index, the more current leakage, and the worse the health of the cable.
The current environmental humidity value of the cable can be measured by a capacitance type humidity sensor through capacitance change. Humidity sensors typically consist of a capacitor with a humidity sensitive dielectric layer sandwiched between two electrodes. When water molecules in the air adhere to the moisture sensitive material, the dielectric constant of the dielectric medium changes, and the capacitance value changes. After the sensor measures the capacitance change, it is converted into a humidity reading by a circuit. The current environmental humidity value of the cable can also be measured by a resistance type humidity sensor by utilizing the resistance change of the humidity sensitive material. When water vapor in the air is absorbed by the moisture sensitive material, the electrical resistance of the material changes. The change in humidity directly affects the change in resistance of the sensor, and by measuring the change in resistance, the relative humidity of the air can be calculated.
The current ambient temperature value of the cable can be measured by a resistance thermometer (such as a platinum resistor PT 100) through the characteristic of the metal resistor changing with temperature. When the temperature is measured, the resistance of metal (such as platinum) increases with the temperature rise, and the resistance change can be converted into a temperature value by circuit measurement. The temperature can also be measured by a thermocouple using the difference in thermoelectric voltages generated by different metallic materials as the temperature changes. The thermocouple is formed by combining two different metal materials, when the temperature changes, the potential difference between the two materials also changes, and the temperature value is obtained by measuring the potential difference.
Through the combination of the parameters with multiple dimensions, the leakage current index not only reflects the insulation state of the cable, but also comprehensively considers the influence of external environment factors such as temperature, humidity and the like on the health state of the cable. Particularly, under the condition of large environmental change, more accurate cable health data can be provided for monitoring personnel.
The insulation voltage acquisition module is used for disconnecting the grounding lead and in a live mode, acquiring a voltage signal of the cable terminal through a voltage acquisition technology, analyzing an insulation voltage index based on the acquired voltage signal, and the insulation voltage index is used for evaluating the insulation state of the cable voltage.
Through high-precision voltage signal acquisition, the voltage insulation performance of the cable can be accurately reflected. During voltage signal acquisition, interference caused by a grounding lead or other electrical factors can be eliminated, so that the measured voltage value is closer to the real situation of the cable insulation state. This helps to find insulation problems early, such as aging, cracking or damage to the outer insulation of the cable, thereby reducing the potential safety hazard of the electrical equipment due to cable failure. The voltage acquisition module provides dynamic real-time data, so that power system management personnel can know the voltage insulation condition of the cable at any time.
The real-time monitoring avoids periodic manual inspection and sampling detection of the cable, improves the monitoring efficiency, and ensures that the insulation performance of the cable is always in a safe range. The disconnection of the grounding lead refers to cutting off the electrical connection between the cable and the grounding system when the health of the cable is monitored, so that the testing equipment can acquire accurate voltage signals without grounding interference, and the testing equipment is usually operated in a live mode to avoid the influence of a grounding loop on the testing result.
The specific acquisition steps of the insulation voltage index comprise the steps of acquiring an insulation resistance value of a cable, a leakage current value at the current time t and an actual voltage signal value at the current time t, preprocessing, normalizing the insulation resistance value of the cable after preprocessing, the leakage current value at the current time t and the actual voltage signal value at the current time t, acquiring a preset standard voltage value from a database, acquiring the weight of the insulation resistance value of the cable to the insulation voltage index, the weight of the leakage current value at the current time t to the insulation voltage index and the weight of the ratio of the actual voltage signal value at the current time t to the preset standard voltage value to the insulation voltage index by an objective weighting method, and obtaining the insulation voltage index by an insulation voltage index calculation formula:
;
wherein JYI is an insulation voltage index, R is an insulation resistance value of the cable, For the weight of R to JYI,As the leakage current value at the present time t,Is thatWith respect to the weights of JYI,For the actual voltage signal value at the present time t,For a preset value of the standard voltage to be reached,Is thatAnd (3) withFor a weight of JYI.
A specific example is the insulation resistance value r=50 ohms of the cable,Leakage current value at present time t=0.35=45mA/km,=0.35, Actual voltage signal value at current time t=9.8 KV, preset standard voltage value=10kV,=0.3, And JYI =0.710 is calculated. The higher the insulation voltage index is, the better the voltage insulation effect is, and the better the health condition of the cable is.
The insulation resistance value of the cable can be obtained through a high-voltage megohmmeter. The actual voltage signal value at the current time t is obtained through a high-precision voltage acquisition technology, wherein the high-precision voltage acquisition technology refers to that the grounding lead acquires the actual voltage signal at the current time t through a high-precision voltage transmitter in a disconnection mode, and the voltage signal acquisition precision reaches the uV level.
The health evaluation module is used for acquiring the leakage current index and the insulation voltage index, analyzing the health condition index according to the leakage current index and the insulation voltage index, and evaluating the health condition of the in-transit cable.
The health evaluation module provides real-time and accurate evaluation of the health state of the cable by comprehensively analyzing the leakage current index and the insulation voltage index, so that not only can the cable fault be predicted in advance, but also the operation and maintenance strategy can be optimized, and unnecessary maintenance and inspection work can be reduced, thereby reducing the operation and maintenance cost and improving the stability and reliability of the power system.
The health condition index obtaining step comprises the steps of obtaining leakage current index and insulation voltage index at the same time t, obtaining weights of the leakage current index and the insulation voltage index on the health condition index respectively through an objective weighting method, and obtaining the health condition index through a health condition index calculation formula. The health index calculation formula is:
;
Wherein JKI is a health index, pi is a circumference ratio, XLI is a leakage current index, JYI is an insulation voltage index, For the weight of XLI to JKI,Is JYI for JKI.
One specific example is xli=0.619,=0.5,=0.5, JYI=0.710, calculated as JKI =0.688. The higher the health index, the better the health of the cable, and conversely, the worse.
And the scoring output alarm module is used for outputting the score of the current cable according to the scoring rule according to the health condition index and automatically alarming according to the score.
The method comprises the steps of outputting the score of the current cable according to a scoring rule, and automatically giving an alarm according to the score, wherein the specific steps are that when the health state index score of the cable is less than 50, the alarm is triggered, power failure is recommended to carry out power failure maintenance on the cable, when the health state index score of the cable is greater than or equal to 50 and less than 80, 1-time live partial discharge and infrared detection are carried out weekly, and when the health state index score of the cable is greater than or equal to 80, the cable is output to be in a relatively healthy state.
The scoring output alarm module clearly distinguishes health states of different grades through the automatically generated health state indexes. According to the score, the maintenance frequency and the maintenance depth are dynamically adjusted, lean management is achieved, a more flexible early warning mechanism is provided, the cable maintenance is more targeted and flexible, and the unnecessary maintenance times are greatly reduced.
Embodiment 2 an on-line monitoring device for detecting health of an on-line cable for implementing the system of embodiment 1, comprising:
the single-phase switch is used for being connected with the ground braid loop in series;
the current transformer is used for collecting current signals through the serial connection braids;
The high-precision voltage transmitter is used for acquiring voltage signals in a grounding lead disconnection mode;
the system comprises a processor and a memory, wherein computer program instructions are stored in the memory, and when the processor is configured to execute the computer program instructions, the single-phase switch, the current transformer and the high-precision voltage transmitter are caused to execute setting actions.
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Citations (2)
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|---|---|---|---|---|
| CN101975914A (en) * | 2010-10-19 | 2011-02-16 | 华中科技大学 | On-line monitoring method and device for insulating state of power cable |
| CN116068324A (en) * | 2023-03-16 | 2023-05-05 | 国网辽宁省电力有限公司电力科学研究院 | Cable line testing method, system, equipment and medium |
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| JP3853134B2 (en) * | 2000-04-25 | 2006-12-06 | 三菱電機ビルテクノサービス株式会社 | Estimating remaining life of power cables |
| KR100817890B1 (en) * | 2006-08-16 | 2008-03-31 | 김보경 | Insulation detection device and insulation detection method of cable line |
| CN116819394A (en) * | 2023-08-24 | 2023-09-29 | 国网浙江省电力有限公司宁波供电公司 | A power cable aging diagnosis and monitoring method and system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101975914A (en) * | 2010-10-19 | 2011-02-16 | 华中科技大学 | On-line monitoring method and device for insulating state of power cable |
| CN116068324A (en) * | 2023-03-16 | 2023-05-05 | 国网辽宁省电力有限公司电力科学研究院 | Cable line testing method, system, equipment and medium |
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