Capacitor fault on-line monitoring method and device

Abstract

The invention discloses a capacitor fault on-line monitoring method and device, and belongs to the technical field of capacitor monitoring, and the method comprises the steps: carrying out the on-line monitoring of the state parameters of a capacitor in the on-line operation process of the capacitor, and enabling the state parameters to mainly comprise temperature difference, pressure, voltage and current; comparing each type of data with a corresponding preset threshold value, and online judging whether the capacitor has a fault or not; through on-line monitoring of the state parameters, the real operation condition of the capacitor under the electrified condition can be monitored in real time, real-time on-line monitoring of the fault of the capacitor is realized, then the capacitor operation can be quitted at the initial stage of the fault so as to carry out proper maintenance and repair, and thus the operation safety is greatly improved, and the working efficiency is improved. And the service life of the equipment is prolonged. In addition, the method is simple, safe, convenient in measurement process, high in operability and high in monitoring accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of capacitor monitoring, and more specifically, relates to a capacitor fault online monitoring method and device. Background Art

[0002] The service life of a capacitor is not only related to its manufacturing technology and quality, but also to its operation and maintenance and the configuration of its control and protection devices. Temperature, pressure, voltage and current are important parameters in its operation. Due to reasons such as raw materials and manufacturing processes, there may be impurities, mechanical damage and other defects in the insulating medium of the capacitor. Due to the influence of overvoltage, overcurrent and temperature rise, the insulating medium of the capacitor will inevitably break down at the defect during operation. If the operation and maintenance are not done properly, this early failure will quickly expand in scope, accompanied by various physical and chemical reactions, and produce a large amount of gas. This causes the internal pressure of the capacitor element to increase, the shell to expand and deform, and even explode. Therefore, when the capacitor is put into operation, its temperature, pressure, voltage and current must be monitored online. At the beginning of the failure, the capacitor should be withdrawn from operation for proper maintenance and repair, which greatly improves the safety of operation and extends the service life of the equipment.

[0003] Power capacitors are widely used in power systems and are one of the important working components in power systems. As an extremely important reactive power source in power systems, capacitors play a decisive role in improving system structure and improving power quality. Especially under the current situation where reliability requirements are increasingly stringent, the operating status of power capacitors is closely related to the power quality of users.

[0004] However, traditional power capacitor testing is usually carried out offline with power off, which affects production. Moreover, offline tests can only reflect the equipment status of the capacitor when it is disconnected from the power grid and under maintenance. It is not restricted by actual operation but is in an environment that effectively eliminates external interference. Therefore, it is impossible to accurately reflect the insulation status of the capacitor and its development trend. It cannot truly represent the actual operating level under live conditions and has great limitations. The relay protection of the capacitor only works after an accident occurs. For example, when an alarm signal is given when overcurrent or three-phase imbalance occurs, it usually indicates that the surface capacitor fault has occurred and has developed into a more serious situation. Years of operating experience have also shown that many faulty power capacitors are usually qualified in the last power outage test. Therefore, it has become a general trend to carry out live monitoring technology for power capacitors, which can reflect the actual operating status of capacitors under live conditions. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a method and device for online monitoring of capacitor faults, which is used to solve the technical problem that the prior art cannot monitor the actual operating conditions of the capacitor when it is energized in real time and cannot perform real-time online monitoring of capacitor faults.

[0006] In order to achieve the above objectives, in a first aspect, the present invention provides a capacitor fault online monitoring method, comprising:

[0007] Real-time acquisition of state parameters of the capacitor to be tested; wherein the state parameters include the following categories of data: temperature difference, pressure, voltage and current of the capacitor to be tested; the temperature difference of the capacitor is the difference between the temperature of the capacitor to be tested and the ambient temperature;

[0008] It is determined whether the data of each category in the state parameter is less than or equal to the corresponding preset threshold value. If so, it is determined that the capacitor to be tested has no fault; otherwise, it is determined that the capacitor to be tested has a fault.

[0009] Further preferably, the preset threshold corresponding to each category of data in the state parameter is determined by the following method:

[0010] When the capacitance of the capacitor to be tested decreases to a preset capacitance, the current state parameters are collected, and the data of each category in the current state parameters is used as the preset threshold value of the corresponding category.

[0011] In a second aspect, the present invention provides a capacitor fault online monitoring device, comprising:

[0012] The acquisition module is used to acquire the state parameters of the capacitor to be tested in real time; wherein the state parameters include the following categories of data: temperature difference, pressure, voltage and current of the capacitor to be tested; the temperature difference of the capacitor to be tested is the difference between the temperature of the capacitor to be tested and the ambient temperature;

[0013] The detection module is used to determine whether the data of each category in the state parameter is less than or equal to the corresponding preset threshold value. If so, it is determined that the capacitor is not faulty; otherwise, it is determined that the capacitor is faulty.

[0014] Further preferably, the above capacitor fault online monitoring device further includes:

[0015] The threshold acquisition module is used to reduce the capacitance of the capacitor to be tested to a preset capacitance, and collect the current state parameters of the capacitor to be tested through the acquisition module, and use each category of data in the current state parameters as the preset threshold of the corresponding category.

[0016] Further preferably, the acquisition module comprises:

[0017] A temperature sensor is used to collect the temperature of the capacitor to be tested in real time;

[0018] A temperature difference calculation module is used to calculate the difference between the temperature of the capacitor to be tested and the ambient temperature to obtain the temperature difference of the capacitor to be tested;

[0019] A pressure sensor is used to collect the pressure of the capacitor to be tested in real time;

[0020] A voltage sensor is used to collect the voltage of the capacitor to be tested in real time;

[0021] The current sensor is used to collect the current of the capacitor to be tested in real time.

[0022] Further preferably, the acquisition module further includes: a voltage transformer;

[0023] The output terminal of the voltage transformer is connected to the input terminal of the voltage sensor;

[0024] The voltage transformer is used to transform the voltage of the capacitor to be measured into the measurement range of the voltage sensor for measurement by the voltage sensor.

[0025] Further preferably, the acquisition module further includes: a current transformer;

[0026] The output end of the current transformer is connected to the input end of the current sensor;

[0027] The current transformer is used to transform the current of the capacitor to be measured into the measurement range of the current sensor for measurement by the current sensor.

[0028] Further preferably, the acquisition module further includes: an analog-to-digital converter;

[0029] The analog-to-digital converter is used to perform analog-to-digital conversion on the temperature collected by the temperature sensor, the pressure collected by the pressure sensor, the pressure collected by the voltage sensor, and the current collected by the current sensor.

[0030] Further preferably, the acquisition module further includes:

[0031] The holding amplifier is used to keep the input analog signal of the analog-to-digital converter unchanged during the analog-to-digital conversion process of the analog-to-digital converter.

[0032] Further preferably, the above capacitor fault online monitoring device further includes:

[0033] The host computer is used to display the status parameters collected by the acquisition module.

[0034] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0035] 1. The present invention provides a method and device for online monitoring of capacitor faults. During the online operation of the capacitor, the state parameters of the capacitor are monitored online, wherein the state parameters mainly include temperature difference, pressure, voltage and current data. Then, by comparing each type of data with the corresponding preset threshold, it is determined online whether the capacitor has a fault. Through the online monitoring of the state parameters, the present invention can monitor the actual operation of the capacitor under power in real time, realize real-time online monitoring of capacitor faults, and then exit the capacitor operation at the early stage of the fault so as to carry out appropriate maintenance and repair, thereby greatly improving the safety of operation and extending the service life of the equipment.

[0036] 2. The capacitor fault online monitoring method and device provided by the present invention are simple, safe, convenient in measurement process, highly operable, and have high monitoring accuracy.

[0037] 3. The capacitor fault online monitoring method and device provided by the present invention can ensure the stability of the test conditions and is not affected by factors such as the external environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The present invention provides a flowchart of a capacitor fault online monitoring method. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] In order to achieve the above objectives, firstly, Figure 1 As shown, the present invention provides a capacitor fault online monitoring method, comprising:

[0041] Real-time acquisition of state parameters of the capacitor to be tested; wherein the state parameters include the following categories of data: temperature difference, pressure, voltage and current of the capacitor to be tested; the temperature difference of the capacitor is the difference between the temperature of the capacitor to be tested and the ambient temperature;

[0042] It is determined whether the data of each category in the state parameter is less than or equal to the corresponding preset threshold value. If so, it is determined that the capacitor to be tested has no fault; otherwise, it is determined that the capacitor to be tested has a fault.

[0043] In an optional implementation manner, the preset threshold corresponding to each category of data in the state parameter is obtained through a destructive experiment:

[0044] When the capacitance of the capacitor to be tested decreases to a preset capacitance, the current state parameters are collected, and the data of each category in the current state parameters is used as the preset threshold value of the corresponding category.

[0045] The preset capacitance is a critical capacitance value for normal operation of the capacitor. When the capacitance is lower than the preset capacitance, the capacitor is damaged. In an optional implementation, the preset capacitance is 5% of the rated capacitance of the capacitor to be tested.

[0046] Preferably, in an optional implementation manner, the above-mentioned ambient temperature is also obtained through real-time collection.

[0047] It should be noted that the present invention provides a capacitor fault online monitoring method, which can perform real-time online monitoring of capacitor state parameters and stipulate different types of data thresholds under critical state parameters under safe operating conditions, such as the temperature difference threshold T max , pressure threshold P max , voltage threshold U max and the current threshold I max When the data of each category in the state parameter is less than or equal to the corresponding preset threshold, the capacitor is judged to be normal and put into operation; when the data of each category in the state parameter is greater than the corresponding preset threshold, the capacitor is judged to be faulty, an alarm is issued, the capacitor is out of operation, and the fault is checked. Online detection of capacitor state parameters is conducive to improving the operational reliability and life of the capacitor.

[0048] In a second aspect, the present invention provides a capacitor fault online monitoring device, comprising:

[0049] The acquisition module is used to acquire the state parameters of the capacitor to be tested in real time; wherein the state parameters include the following categories of data: temperature difference, pressure, voltage and current of the capacitor to be tested; the temperature difference of the capacitor to be tested is the difference between the temperature of the capacitor to be tested and the ambient temperature;

[0050] The detection module is used to determine whether the data of each category in the state parameter is less than or equal to the corresponding preset threshold value. If so, it is determined that the capacitor to be tested has no fault; otherwise, it is determined that the capacitor to be tested has a fault.

[0051] In an optional implementation manner, the above capacitor fault online monitoring device further includes:

[0052] The threshold acquisition module is used to reduce the capacitance of the capacitor to be tested to a preset capacitance, and collect the current state parameters of the capacitor to be tested through the acquisition module, and use each category of data in the current state parameters as the preset threshold of the corresponding category.

[0053] In an optional implementation manner, the acquisition module includes:

[0054] A temperature sensor is used to collect the temperature of the capacitor to be tested in real time;

[0055] A temperature difference calculation module is used to calculate the difference between the temperature of the capacitor to be tested and the ambient temperature to obtain the temperature difference of the capacitor to be tested;

[0056] A pressure sensor is used to collect the pressure of the capacitor to be tested in real time;

[0057] A voltage sensor is used to collect the voltage of the capacitor to be tested in real time;

[0058] The current sensor is used to collect the current of the capacitor to be tested in real time.

[0059] Preferably, in an optional implementation manner, the acquisition module comprises: a temperature sensor for acquiring the ambient temperature in real time, and the ambient temperature is also acquired through real-time acquisition.

[0060] In an optional implementation, during the data collection process, a program control method is adopted, a sampling transmission control query method is adopted, the sampling period is determined by the program control time, and time-sharing sampling is performed on different categories of data in the state parameters to centrally process the data.

[0061] In an optional implementation manner, the acquisition module further includes: a voltage transformer;

[0062] The output terminal of the voltage transformer is connected to the input terminal of the voltage sensor;

[0063] The voltage transformer is used to transform the voltage of the capacitor to be measured into the measurement range of the voltage sensor for measurement by the voltage sensor.

[0064] In an optional implementation manner, the acquisition module further includes: a current transformer;

[0065] The output end of the current transformer is connected to the input end of the current sensor;

[0066] The current transformer is used to transform the current of the capacitor to be measured into the measurement range of the current sensor for measurement by the current sensor.

[0067] In an optional implementation, the acquisition module further includes: an analog-to-digital converter;

[0068] The analog-to-digital converter is used to perform analog-to-digital conversion on the temperature collected by the temperature sensor, the pressure collected by the pressure sensor, the pressure collected by the voltage sensor, and the current collected by the current sensor.

[0069] In an optional implementation manner, the acquisition module further includes:

[0070] The holding amplifier is used to keep the input analog signal of the analog-to-digital converter unchanged during the analog-to-digital conversion process of the analog-to-digital converter.

[0071] In an optional implementation manner, the above capacitor fault online monitoring device further includes:

[0072] The host computer is used to display the status parameters collected by the acquisition module.

[0073] Furthermore, in an optional implementation manner, the above capacitor fault online monitoring device further includes: a multiplexer circuit;

[0074] The multiplexer circuit integrates the data of various categories in the state parameters collected by the sensor at the same time, and after conversion through the analog-to-digital converter, uploads it to the host computer for display. By displaying the change of state parameters over time on the host computer, it is more convenient to further analyze the operating status of the capacitor.

[0075] Since the capacitor will be damaged by insulation and excessive internal pressure under the effect of excessive temperature rise, overvoltage and overcurrent for a long time, the service life of the capacitor will be greatly reduced, and the insulation may collapse or even explode. The present invention detects some parameters of the capacitor during operation, such as temperature, pressure, voltage and current, and describes the method of online monitoring of these parameters, realizing online monitoring and protection of the capacitor, which is very necessary for the safe operation of the capacitor and extending its service life. The test device of the present invention is simple, the measurement method is convenient, and the operability is strong. It puts forward certain suggestions for the online monitoring of the capacitor, which is conducive to maintaining the normal operation of the capacitor and has a significant impact.

[0076] In summary, the capacitor fault online monitoring method and device provided by the present invention can help detect the online state parameters of different capacitors and perform feature analysis for the next step. Since the detection and fault judgment of capacitors are currently based on offline detection of capacitors, a complete system has not been formed for online detection of capacitors. If the capacitor can be effectively detected online and the online detection parameters can be judged, the capacitor with abnormal state parameters can be exited at the beginning of the fault, and the capacitor can be properly maintained and repaired according to the relationship between the capacitor online detection operation state parameters and the threshold value. This greatly improves the safety of operation, extends the service life of the equipment, avoids the defect damage of the insulating medium caused by raw materials and manufacturing processes, and cannot obtain the real-time online operation state of the capacitor. Finally, the capacitor is severely damaged and a large amount of fault defect gas is generated. Finally, the capacitor bulges, endangering the safety of the site and causing explosions. The present invention provides some theoretical basis for the design of the insulation structure and the development of the insulation material, and also provides some evaluation methods for the manufacture and operation and maintenance of some high-voltage DC electrical equipment such as high-voltage capacitors.

[0077] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A capacitor fault online monitoring method, characterized in that: include: Real-time acquisition of state parameters of the capacitor to be tested; wherein the state parameters include the following categories of data: temperature difference, pressure, voltage and current of the capacitor to be tested; the temperature difference of the capacitor to be tested is the difference between the temperature of the capacitor to be tested and the ambient temperature; It is determined whether the data of each category in the state parameter is less than or equal to the corresponding preset threshold value. If so, it is determined that the capacitor to be tested does not have a fault; otherwise, it is determined that the capacitor to be tested has a fault.

2. The capacitor fault online monitoring method according to claim 1, characterized in that: The preset threshold corresponding to each category of data in the state parameter is determined in the following manner: When the capacitance of the capacitor to be tested decreases to a preset capacitance, current state parameters are collected, and data of each category in the current state parameters is used as a preset threshold value of the corresponding category.

3. A capacitor fault online monitoring device, characterized in that: include: The acquisition module is used to acquire the state parameters of the capacitor to be tested in real time; wherein the state parameters include the following categories of data: temperature difference, pressure, voltage and current of the capacitor to be tested; the temperature difference of the capacitor to be tested is the difference between the temperature of the capacitor to be tested and the ambient temperature; The detection module is used to determine whether the data of each category in the state parameter is less than or equal to the corresponding preset threshold value. If so, it is determined that the capacitor to be tested has no fault; otherwise, it is determined that the capacitor to be tested has a fault.

4. The capacitor fault online monitoring device according to claim 3 is characterized in that: Also includes: The threshold acquisition module is used to reduce the capacitance of the capacitor to be tested to a preset capacitance, and collect the current state parameters of the capacitor to be tested through the acquisition module, and use each category of data in the current state parameters as the preset threshold of the corresponding category.

5. The capacitor fault online monitoring device according to claim 3, characterized in that: The acquisition module comprises: A temperature sensor, used for collecting the temperature of the capacitor to be tested in real time; A temperature difference calculation module, used to calculate the difference between the temperature of the capacitor to be tested and the ambient temperature, and obtain the temperature difference of the capacitor to be tested; A pressure sensor, used for collecting the pressure of the capacitor to be tested in real time; A voltage sensor, used for collecting the voltage of the capacitor to be tested in real time; The current sensor is used to collect the current of the capacitor to be tested in real time.

6. The capacitor fault online monitoring device according to claim 5, characterized in that: The acquisition module also includes: a voltage transformer; The output end of the voltage transformer is connected to the input end of the voltage sensor; The voltage transformer is used to transform the voltage of the capacitor to be measured into a measurement range of the voltage sensor for measurement by the voltage sensor.

7. The capacitor fault online monitoring device according to claim 5, characterized in that: The acquisition module also includes: a current transformer; The output end of the current transformer is connected to the input end of the current sensor; The current transformer is used to transform the current of the capacitor to be measured into a measurement range of the current sensor for measurement by the current sensor.

8. The capacitor fault online monitoring device according to any one of claims 5 to 7, characterized in that: The acquisition module also includes: The analog-to-digital converter is used to perform analog-to-digital conversion on the temperature collected by the temperature sensor, the pressure collected by the pressure sensor, the pressure collected by the voltage sensor, and the current collected by the current sensor.

9. The capacitor fault online monitoring device according to claim 8, characterized in that: The acquisition module also includes: The holding amplifier is used to keep the input analog signal of the analog-to-digital converter unchanged during the analog-to-digital conversion process of the analog-to-digital converter.

10. The capacitor fault online monitoring device according to claim 3, characterized in that: Also includes: The host computer is used to display the status parameters collected by the collection module.

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