CN110045273B - SF (sulfur hexafluoride)6Online monitoring method for ablation degree of breaker contact - Google Patents
SF (sulfur hexafluoride)6Online monitoring method for ablation degree of breaker contact Download PDFInfo
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- CN110045273B CN110045273B CN201910231792.6A CN201910231792A CN110045273B CN 110045273 B CN110045273 B CN 110045273B CN 201910231792 A CN201910231792 A CN 201910231792A CN 110045273 B CN110045273 B CN 110045273B
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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
- G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
- G01R31/3271—Testing of circuit interrupters, switches or circuit-breakers of high voltage or medium voltage devices
- G01R31/3275—Fault detection or status indication
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Abstract
The invention relates to SF6On-line monitoring of ablation degree of breaker contactAnd (4) a measuring method. The invention provides a method for monitoring SF (sulfur hexafluoride) from a novel angle6The method for judging the ablation degree of the contact of the circuit breaker does not have the problem of homology with the existing judging method and is used for SF6The circuit breaker is directly monitored at the moment instead of an indirect detection method. Various factors are comprehensively considered from multiple aspects of device design, installation position, safety, anti-interference performance and the like, and the accuracy, the accuracy and the anti-interference capability of the method are improved; the high-precision CCD measuring instrument and the electromagnetic field sensor are selected as the signal acquisition device, so that SF is realized6And calibrating the moment of just dividing the circuit breaker and the arcing moment. In addition, the method has the advantages of low cost, strong practicability and convenience for operating SF at present6The circuit breaker is installed, and is suitable for popularization and application.
Description
Technical Field
The invention relates to SF6An online monitoring method for ablation degree of a breaker contact.
Background
High pressure SF6The circuit breaker is a key device of a power grid and a transformer substation and is a primary device with large use amount; high pressure SF6The circuit breaker should have the basic functions of good conduction in a closed state, rated short-circuit current interruption in a short time when the circuit breaker is disconnected, and the like; however, in the process of breaking rated short circuit current of the circuit breaker, the contact can be ablated due to the generation of electric arc, if the contact of the circuit breaker is seriously burnt, the normal function of the circuit breaker can be influenced, even serious accidents such as the failure of the circuit breaker or the failure of the breaking current are caused, and the explosion chamber of the circuit breaker can be exploded more seriouslyThe losses caused by explosion far exceed the value of the circuit breaker itself. Thus, SF6The ablation degree judgment of the breaker contact has important significance in breaker state monitoring. At present, SF6The method for judging the ablation degree of the contact of the circuit breaker mainly comprises the following steps: a circuit breaker on-off current weighted accumulation method, a dynamic resistance-stroke curve method and the like; however, these methods have certain limitations, and therefore, there is a need to research a method capable of accurately determining SF6On-line monitoring method for ablation degree of breaker contact, improving monitoring SF6The accuracy of judging the ablation degree of the contact of the circuit breaker provides technical support and equipment support for realizing the safety, stability and coordination control of a power grid.
At present, SF6The method for judging the ablation degree of the contact of the circuit breaker mainly comprises the following steps: a cut-off current weighted accumulation method, a dynamic resistance-stroke curve method and the like.
The method is a method for monitoring ablation degree of the breaker on line. The method weights and accumulates the breaking current of the circuit breaker according to the electric service life curve of the circuit breaker, and then calculates the accumulated electric abrasion quantity Q and the allowable electric abrasion total quantity QgAnd comparing, so that only the effective value of the cut-off current needs to be monitored. However, the method does not consider the difference between three phases when the breaker operates, and especially when the fault phase and the non-fault phase are disconnected, if the fault phase current is accumulated, the accumulated abrasion loss of the non-fault phase is larger; in addition, the method is an average statistical method, the more the switching-off times are, the more accurate the switching-off times are, but the different short-circuit currents and the different ablation amounts of each switching-off process generate larger differences. This method can only be used as a method of roughly estimating the degree of ablation.
The dynamic resistance-travel curve method is a method which is widely applied at present to evaluate the state of a contact. The method adopts a four-wire method to eliminate errors caused by contact resistance of the wiring point so as to obtain a dynamic resistance-stroke curve, obtains the stroke time of the dynamic resistance of the contact of the circuit breaker and the size of the dynamic resistance value through analysis, and takes the result as the judgment basis of the ablation degree of the contact of the circuit breaker. However, the method needs to be measured off-line, the ablation degree of the contact of the circuit breaker cannot be known in real time, the requirement of regular inspection can only be met, the requirement of real-time on-line monitoring cannot be met, a direct current source and a high-precision voltage measuring device are needed, and the method is huge and expensive in equipment and easy to interfere.
Disclosure of Invention
The invention adopts a high-precision CCD measuring instrument and a high-precision magnetic field sensor as signal acquisition devices. The high-precision CCD measuring instrument is used for measuring the specific gallium nitride green LED of the head, provides short wavelength and reliable operation, and is favorable for precise detection and control. The high-precision magnetic field sensor can accurately capture the high-frequency electromagnetic radiation generated by the electric arc, and further accurately judge the SF6The moment of arcing of the circuit breaker. Because the movable contact fingers can generate larger interference due to collision in the closing process, the ablation degree diagnosis and monitoring are carried out only by selecting the opening process. In addition, the sensor adopted by the invention is not contacted with the electrified part of the circuit breaker, so that the stability and the reliability are high, and the sensor is not interfered with and influenced by the high-voltage conducting part of the circuit breaker.
The invention mainly comprises the following steps:
the first step is as follows: obtaining SF6Circuit breaker contact travel time curve and dynamic resistance curve, calibration SF6The main contact and the arc contact of the circuit breaker are in the initial just-separating position.
The invention adopts a high-precision CCD tester to measure the travel time curve of the contact; method for determining moment t of main contact just divided by adopting dynamic resistance method1Moment t just after arc contact0(ii) a According to t1And t0Respectively calibrating the rigid-dividing position L of the main contact on the travel time curve of the contact1And the rigid-dividing position L of the arcing contact0。
The calibration circuit is shown in fig. 1, and the external direct current source selected in the calibration circuit is proper in size, so that an arc cannot be generated when the circuit breaker acts. The testing power supply selects direct current, measures voltage generated on the contact by current in the switching-on and switching-off process, and processes according to ohm's law to obtain a change curve of contact resistance between the moving contact and the static contact.
High precision CCD test of the present inventionThe instrument and the installation method of the thin insulating light barrier are shown in figure 2, the high-precision CCD tester is installed at a position close to the transmission rod, the thin insulating light barrier is fixed at the tail end of the insulating pull rod of the circuit breaker, when the circuit breaker acts to open the gate, the thin insulating light barrier moves in the direction of an arrow shown in the figure, and the fracture voltage and the signal of the high-precision CCD tester are monitored at the same time. The measured dynamic resistance curve is shown in fig. 3, and the break voltage sudden change signal can be used as a mark of the just-broken position of the contact of the circuit breaker. When the fracture voltage monitors the signal shown in FIG. 3, t is illustrated0The moment is just the moment of the arc contact of the circuit breaker, and the high-precision CCD tester records t0The position of the light barrier at the moment is taken as SF6And (3) the initial rigid-breaking position of the breaker contact (namely, the high-precision CCD tester records the initial rigid-breaking position of the breaker arc contact). In addition, the light blocking plate can block light rays in the action process of the circuit breaker, so that the light receiving quantity of a receiving end of the high-precision CCD tester is changed, and the stroke curve of the circuit breaker shown in fig. 3 can be drawn through the change of the light receiving quantity of the receiving end; meanwhile, a speed curve of the contact of the circuit breaker can be obtained according to the stroke curve.
The second step is that: obtaining SF6The breaker contact in the working process of the breaker just divides the position in real time.
The circuit breaker action in-process can produce electric arc, and then leads to the circuit breaker contact to take place to ablate, along with the increase of circuit breaker action number of times, contact ablation degree is more and more serious, and the overtravel shortens, and the circuit breaker just minute moment changes. Therefore, a method for monitoring the position of the contact of the circuit breaker just after the contact is separated in real time on line is needed. Due to the breakdown process after the contact separation, the electromagnetic radiation of the high-frequency space is stronger, so that the electromagnetic radiation can be monitored to be used as a judgment basis for the moment when the contact of the circuit breaker is just separated. The invention adopts a high-precision magnetic field sensor to collect electromagnetic field signals of electric arcs generated at the contact of the circuit breaker, and the magnetic field signals collected by the sensor when the circuit breaker acts are shown in figure 3. Multiple experiments show that the time t when the signal begins to mutatemNamely the real-time just minute time of the breaker contact, the method can be adopted as an online monitoring method of the real-time just minute position of the breaker contact. And tmArc contact just-divided position L corresponding to momentmShould be in the main contact just-separating position L0And the rigid-dividing position L of the arcing contact1In the meantime.
The third step: SF6And evaluating the electrical life of the arc contact of the circuit breaker.
And obtaining the ablation degree of the contact from the stroke curve of the circuit breaker according to the initial and real-time just-divided position moments of the contact of the circuit breaker. And simultaneously acquiring signals of the high-precision CCD tester, the high-precision magnetic field sensor and the circuit breaker stroke curve during each circuit breaker action, and drawing three signals on the same coordinate axis, as shown in figure 3. From fig. 3, the time difference Δ t between the real-time just-separating position of the breaker arc contact and the initial just-separating position of the breaker arc contact and the stroke difference Δ L of the breaker arc contact on the stroke curve can be clearly obtained, and the stroke difference can represent the ablation degree of the breaker contact.
In general, SF6The over-travel length of the circuit breaker is D, and the ratio k of the travel difference Delta L to the over-travel D of the circuit breaker is used as the judgment basis of the ablation degree of the circuit breaker. When k is<When the contact is 0.3, judging that the contact of the circuit breaker is good; when k is 0.3-0.5, judging that the contact of the circuit breaker is moderately ablated, and giving a warning signal; when k is>When the contact ablation rate is 0.7, the circuit breaker contact is judged to be serious, and timely maintenance is needed.
Drawings
1. FIG. 1 is a schematic diagram of a calibration circuit at a time just before, in which a DC voltage source is applied.
2. Fig. 2 is a schematic diagram of the apparatus, wherein the names of the parts are [ 1: high accuracy CCD measuring apparatu receiving end 0 scale position 2: the high-precision CCD measuring instrument receiving end initial just divides the moment and marks scale 3: high-precision CCD measurement instrument receiving end 4: thin insulating light barrier 5: high-precision CCD measuring instrument transmitting end 6: breaker moving contact transmission rod 7: and the motion direction of the transmission rod when the breaker is opened.
3. FIG. 3 shows waveforms of the high-precision CCD measurement device and the high-precision magnetic field sensor, which are plotted on the same coordinate axis, wherein the parameters are [ t [ ]0: on-line monitoring circuit breaker contact moment t1: initial just-divided time delta t of a breaker contact:circuit breaker contacts just time differential.
Detailed Description
The invention mainly comprises the following steps:
the first step is as follows: the sensor is mounted as per fig. 2.
The second step is that: obtaining SF6Circuit breaker contact travel time curve and dynamic resistance curve, calibration SF6The main contact and the arc contact of the circuit breaker are in the initial just-separating position.
The third step: obtaining SF6The breaker contact in the working process of the breaker just divides the position in real time.
The fourth step: SF6And evaluating the electrical life of the arc contact of the circuit breaker.
Key point and point to be protected of the proposal of the application
The key points are as follows: the invention adopts SF calibrated based on a CCD measuring instrument6SF for on-line monitoring of initial just-separating position of breaker contact and magnetic field sensor6The stroke difference of the real-time just-divided position of the contact of the circuit breaker is used as the judgment basis of the ablation degree, and the invention adopts the high-precision CCD measuring instrument as the newly-installed SF6The invention relates to a sensor calibrated at the initial position of a circuit breaker, wherein when the light barrier is thin, the lower edge of the barrier is ensured to be within the measurement range of a high-precision CCD (charge coupled device) measuring instrument, and the height of the light barrier is larger than the measurement width of the sensor.
Protection points: 1. SF calibrated based on CCD measuring instrument6SF for on-line monitoring of initial just-separating position of breaker contact and magnetic field sensor6The stroke difference of the real-time just-divided position of the breaker contact is used as an ablation degree judgment basis;
2. the invention adopts the high-precision CCD measuring instrument as the newly installed SF6A sensor for calibrating the initial position of the circuit breaker;
3. when the thin insulating light barrier is used, the lower edge of the barrier is ensured to be within the measuring range of the high-precision CCD measuring instrument, and the height of the light barrier is larger than the measuring width of the sensor;
4. the invention can realize on-line measurement;
5. installation method and position of each module of the sensor.
Claims (1)
1. SF (sulfur hexafluoride)6The method for monitoring the ablation degree of the contact of the circuit breaker on line comprises the following steps: obtaining SF6Circuit breaker contact stroke curve and dynamic resistance curve, calibration SF6The initial rigid separation position of a main contact and an arc contact of the circuit breaker; the high-precision CCD tester is arranged at a position close to the transmission rod, the thin insulating light barrier is fixed at the tail end of the insulating pull rod of the circuit breaker, and the light barrier can block light rays in the action process of the circuit breaker, so that the light receiving quantity of a receiving end of the high-precision CCD tester is changed, and a stroke curve of the circuit breaker is drawn through the change of the light receiving quantity of the receiving end; method for determining moment t of main contact just divided by adopting dynamic resistance method1Moment t just after arc contact0According to t1And t0Respectively calibrating the rigid-dividing position L of the main contact on the travel curve of the contact1And the rigid-dividing position L of the arcing contact0(ii) a The second step is that: obtaining SF6The circuit breaker contact just divides the position in real time in the working process of the circuit breaker; the time t when the signal begins to change suddenly is determined by monitoring the space high-frequency electromagnetic radiation generated in the breakdown process after the contact is separated as the judgment basis of the moment when the contact of the circuit breaker is just separatedmNamely the real-time just-divided moment t of the breaker contactmThe corresponding position on the travel curve of the contact is the real-time just-divided position L of the contactm(ii) a The third step: SF6Evaluating the electrical life of the arc contact of the circuit breaker; the method comprises the steps that signals of a high-precision CCD tester, high-precision magnetic field sensors and a breaker stroke curve are collected at the same time when a breaker acts each time, three paths of signals are drawn on the same coordinate axis, the time difference delta t between the real-time just-dividing position of a breaker arc contact and the initial just-dividing position of the breaker arc contact and the stroke difference delta L of the breaker arc contact and the initial just-dividing position of the breaker arc contact on the stroke curve are obtained, and the stroke difference represents the ablation degree of the breaker contact; the specific value k of the stroke difference delta L and the over-stroke D of the breaker is used as the judgment basis of the ablation degree of the breaker; when k is<When the contact is 0.3, judging that the contact of the circuit breaker is good; when k is 0.3-0.5, judging that the contact of the circuit breaker is moderately ablated, and giving a warning signal; when k is>＝0And 7, judging that the contact of the circuit breaker is seriously ablated and needing to be overhauled in time.
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110571070B (en) * | 2019-08-22 | 2021-07-30 | 南方电网科学研究院有限责任公司 | Method for evaluating breaking performance of circuit breaker |
| CN113311321B (en) * | 2021-05-27 | 2023-06-23 | 云南电网有限责任公司电力科学研究院 | Method for detecting three-phase arc extinguishing performance of circuit breaker based on separation algorithm |
| CN114252765A (en) * | 2021-12-14 | 2022-03-29 | 广西电网有限责任公司桂林供电局 | SF based on switching-on pre-breakdown6Method for evaluating ablation state of breaker contact |
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