A method and system for measuring the unevenness coefficient of the voltage distribution of a circuit breaker break

Abstract

The present application belongs to the field of DC power transmission system operation and maintenance technology, and particularly relates to a method and system for measuring the uneven coefficient of the breaker gap voltage distribution. The present application applies a DC voltage to one side of the double gap, and the other side is grounded. One of the gaps is composed of a ball gap and a loop. The gap voltage is directly measured through the ball gap induction, which eliminates the influence of factors such as partial discharge, surrounding equipment corona, circuit breaker support, etc. and ensures that the measured breaker gap and the measurement ball gap main part are non-contact, which can avoid introducing a parallel resistance-capacitance loop and improve the measurement accuracy. The present application directly converts the electric field value into the voltage value of the two ends of one of the gaps by setting an electric field sensor inside the ball to calculate the uneven coefficient, without making the discharge ball gap break down. The measurement voltage can be flexibly adjusted, and the distance between the ball gaps is fixed when the measurement voltage is changed, so there is no need for adjustment, thus improving the measurement efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of DC power transmission system operation and maintenance, and particularly relates to a method and system for measuring a non-uniform coefficient of voltage distribution of a circuit breaker. BACKGROUND

[0002] The double-break circuit breaker is widely used in power systems, and the high-speed switch (HSS) is one of them. The HSS is a key device in a multi-terminal DC power transmission system, mainly used in a multi-terminal flexible DC power transmission system to realize online switching of a third station in a DC system and high-speed isolation of a DC line fault, thereby improving the reliability and availability of the entire DC system.

[0003] Since the arc-extinguishing chamber of an ultra-high voltage circuit breaker is generally composed of two or more than two breaks in series, although the internal structures of the two arc-extinguishing chambers are the same, the resistance between the breaks and the ground resistance of the insulating pillars will cause the DC voltage distribution between the two breaks to be non-uniform in the open state, and the non-uniform coefficient of the breaks is used to represent the degree of non-uniformity of the voltage distribution between the breaks. In particular, for the DC high-speed switch device operating in a DC working condition, if the non-uniform coefficient of the DC voltage distribution is too large, it will cause two key engineering operation risks:

[0004] ① In the open state of the HSS, the DC voltage amplitudes borne by the two breaks are inconsistent, while the insulating margin of the original product is designed according to the voltage amplitude of the voltage distribution between the breaks, which will cause the voltage amplitude borne by a certain break to exceed the design value, resulting in an insulating breakdown fault in operation;

[0005] ② The DC high-speed switch does not have a ringing circuit, meaning that there is no artificially created current zero point, and the breaking difficulty is greater. The breaking current and the maximum recovery voltage that can be tolerated are mutually restrictive, that is, the greater the breaking DC current, the lower the maximum recovery voltage that can be tolerated. This is related to the recovery ability of the insulating medium and the negative resistance characteristic of the DC arc. Moreover, the DC voltage distribution between the two breaks will affect the success rate of breaking a small DC current, so compared with ordinary AC circuit breakers, the DC voltage distribution between the two breaks will directly affect the breaking effect of the DC current.

[0006] Therefore, in order to apply a suitable voltage value in the single-break insulating test and single-break electric field simulation calculation, and to truly reflect the insulating performance of the overall product, the non-uniform coefficient of the breaks needs to be accurately measured to guide the design of the external insulating structure size of the circuit breaker breaks. If the non-uniform coefficient of the circuit breaker breaks is too large, the voltage distribution between the breaks of the arc-extinguishing chamber can be made uniform by setting a parallel voltage-sharing resistor-capacitor device or the dry-arc distance of the breaks can be lengthened to improve the voltage-withstanding capability of the circuit breaker breaks.

[0007] The microammeter measurement method and the ball gap breakdown voltage method are usually used to measure the uneven coefficient of the fracture in the prior art. The microammeter measurement method detects the conductance characteristics of the double fracture of the circuit breaker under the direct current high voltage by connecting a microammeter to each of the two fractures of the circuit breaker, so as to evaluate the voltage distribution of the circuit breaker. Since the leakage current is generally in the order of μA, the measurement system has high accuracy, and the leakage current is greatly affected by the partial discharge or the corona of the surrounding equipment, so that the leakage current fluctuates greatly on site, and the measurement result of the uneven coefficient is not reliable. The ball gap breakdown voltage method needs to adjust the length of the discharge ball gap, and the output voltage of the direct current high voltage generator is adjusted by the direct current control device, so that the discharge ball gap is broken down to measure the fracture voltage. The length of the discharge ball gap is difficult to adjust on site, and the fracture voltage needs to be measured by allowing the discharge ball gap to break down, which increases the difficulty and danger of the test, and thus reduces the test efficiency. SUMMARY

[0008] The purpose of the present application is to provide a method and system for measuring the uneven coefficient of the fracture voltage distribution of a circuit breaker, which can solve the problem that the detection method of the uneven coefficient of the fracture in the prior art cannot balance the accuracy and efficiency of the measurement.

[0009] In order to achieve the above purpose, the present application provides a system for measuring the uneven coefficient of the fracture voltage distribution of a circuit breaker, wherein the circuit breaker is a double fracture circuit breaker, and the system comprises a first ball, a suspension structure, a second ball, a support structure, a sensor, a measurement module and a processor.

[0010] The suspension structure is an insulator for suspending the first ball in the air, and the support structure is also an insulator arranged directly below the first ball for fixing the second ball at a position with a set distance directly below the first ball.

[0011] The first ball is a conductor for connecting the three-way box of the double fracture circuit breaker through a wire.

[0012] The second ball is a conductor with a cavity structure for grounding. The sensor comprises a perforated cover, a rotating blade, a rotating shaft and a motor, and the rotating blade is arranged between the perforated cover and the motor. The rotating blade is connected to the motor through the rotating shaft, and the motor is used to control the rotating blade to rotate at a set speed through the rotating shaft. The perforated cover and the rotating blade are arranged on the connection line between the centers of the first ball and the second ball. The perforated cover is arranged on the surface of the second ball, and the rotating blade is arranged in the internal space of the second ball, which is surrounded by the perforated cover and the inner wall of the second ball. The rotating shaft direction of the rotating blade is consistent with the connection line direction between the centers of the first ball and the second ball, and the area of the rotating blade blocked by the perforated cover changes with the position of the rotating blade.

[0013] The measuring module comprises a measuring device and a conversion resistor; one end of the conversion resistor is connected to the rotating shaft through a wire, and the other end is used for grounding, for converting the alternating current generated on the rotating blade into a voltage across the conversion resistor; the measuring device is connected in parallel with the conversion resistor, for measuring the voltage across the conversion resistor and taking the voltage across the conversion resistor as the measurement result of the measuring device;

[0014] The processor is used for executing program instructions to realize the circuit breaker voltage uneven distribution coefficient measuring steps as follows:

[0015] 1) a voltage value of a set size is applied to the end of the grading ring of one of the two breaking points of the double-break circuit breaker, and the end of the grading ring of the other breaking point is grounded;

[0016] 2) the motor is controlled to be turned on, the alternating current generated on the rotating blade is converted into a voltage across the conversion resistor by the conversion resistor, the voltage is obtained by the measuring device, and the actual voltage value between the first sphere and the second sphere is obtained according to the calibration conversion relationship, as the voltage value borne by the breaking point with the grounded end of the grading ring;

[0017] 3) the circuit breaker breaking point voltage uneven distribution coefficient is calculated according to the voltage value applied to the end of the grading ring of the breaking point and the voltage value borne by the breaking point with the grounded end of the grading ring.

[0018] The beneficial effects of the above technical solution are: the breaking point voltage is directly measured through the sphere gap induction, the influence of factors such as partial discharge, surrounding equipment corona, circuit breaker support on the breaking point voltage distribution is excluded; and the circuit breaker breaking point to be measured and the main part of the measuring sphere gap are non-contact, the parallel resistance-capacitance circuit is avoided to be introduced, and the accuracy of the voltage distribution measurement is avoided to be affected; the electric field sensor is arranged in the sphere, the electric field value can be directly converted into the voltage value across the two ends of one of the breaking points, so that the breaking point voltage uneven distribution coefficient is calculated, the distance between the sphere gaps is fixed when the measurement voltage is changed, and it is not necessary to adjust or use the sphere gap breakdown to obtain the voltage value, the measurement voltage can be relatively simply and flexibly adjusted, and therefore the measurement efficiency can be improved.

[0019] Further, the formula for calculating the breaking point uneven distribution coefficient is:

[0020]

[0021] U2=U-U1

[0022] In the formula, f is the circuit breaker breaking point voltage uneven distribution coefficient, U is the voltage value applied to the end of the grading ring of the breaking point, U1 is the voltage value borne by the breaking point with the grounded end of the grading ring, and U2 is the voltage value borne by the breaking point with the applied voltage end of the grading ring.

[0023] Further, the way of obtaining the calibration conversion relationship is: the voltage is directly applied on the triple box, the voltage value applied on the triple box and the voltage value of the measurement result of the measuring device are obtained, and the corresponding relationship is taken as the calibration conversion relationship between the actual voltage value between the first sphere and the second sphere and the voltage value of the measurement result of the measuring device.

[0024] The above technical solution has the beneficial effect that the measurement result of the measuring device is accurately converted into the actual voltage value between the first sphere and the second sphere, without the need to actually detect the voltage value between the spheres, thereby simplifying the measurement method while ensuring accuracy.

[0025] Further, the set distance is related to the voltage value applied to the voltage equalizing ring end of the fracture, and the greater the voltage value applied to the voltage equalizing ring end of the fracture, the greater the value of the set distance.

[0026] Further, the first sphere and / or the second sphere is a hollow spherical shell structure.

[0027] The above technical solution has the beneficial effect that the cost can be saved and the influence of the weight of the sphere A on safety can be avoided.

[0028] Further, the number of holes on the hole cover sheet is the same as the number of rotating blades, the positions of the holes on the hole cover sheet correspond to the positions of the rotating blades respectively, and the number of holes and the number of rotating blades are both even.

[0029] Further, the measuring device is arranged on the ground at the position of the support structure.

[0030] The above technical solution has the beneficial effect that the measuring device is arranged on the ground at the position of the support structure, which can maximize the avoidance of the attenuation of the electric signal when the detection result of the measuring module is transmitted through the cable in a high-voltage environment, thereby improving the accuracy of the measurement result.

[0031] Further, the lead connecting the first sphere and the triple box of the double-fracture circuit breaker, the power line and the control line corresponding to the sensor, the controller corresponding to the motor, and the measuring module are all sleeved with aluminum foil bellows.

[0032] The above technical solution has the beneficial effect that it can play a shielding protection role to avoid errors in the control process or the electric signal transmission process due to the interference of the high-voltage environment.

[0033] Further, the conversion resistor is arranged in the internal space of the second sphere.

[0034] The application also provides a method for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage, which is realized by the system for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage as described above, and the measuring steps are as follows:

[0035] 1) a voltage value of a set size is applied to the grading ring end of one of the breaking points of the double breaking point circuit breaker, and the grading ring end of the other breaking point is grounded;

[0036] 2) the motor is controlled to be turned on, the alternating current generated on the rotating vane is converted into the voltage between the two ends of the conversion resistance by the conversion resistance, the voltage is obtained by the measuring device, and the actual voltage value between the first sphere and the second sphere is obtained according to the calibration conversion relationship, as the voltage value borne by the breaking point with the grounded grading ring end;

[0037] 3) the uneven distribution coefficient of the circuit breaker breaking point voltage is calculated according to the voltage value applied to the grading ring end of the breaking point and the voltage value borne by the breaking point with the grounded grading ring end.

[0038] The method for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage can realize the same beneficial effects as the system for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 FIG. 1 is a structural schematic diagram of the measuring system in the system embodiment of the application for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage;

[0040] Figure 2a FIG. 2 is an installation mode and structural schematic diagram of the sensor in the sphere B in the system embodiment of the application for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage;

[0041] Figure 2b FIG. 3 is a structural schematic diagram of the opening cover of the sensor in the system embodiment of the application for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage;

[0042] Figure 3 FIG. 4 is a calibration conversion relationship curve in the system embodiment of the application for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage;

[0043] Figure 4a FIG. 5 is a sensor output signal schematic diagram when the voltage is 108 kV in the system embodiment of the application for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage;

[0044] Figure 4b FIG. 6 is a sensor output signal schematic diagram when the voltage is 198 kV in the system embodiment of the application for measuring the uneven distribution coefficient of the circuit breaker breaking point voltage;

[0045] Figure 4cThe schematic diagram of sensor output signal when 301kV is applied in the system embodiment of the application for measuring the uneven distribution coefficient of circuit breaker breaking point voltage;

[0046] Figure 4d The schematic diagram of sensor output signal when 401kV is applied in the system embodiment of the application for measuring the uneven distribution coefficient of circuit breaker breaking point voltage;

[0047] Figure 5 The curve diagram of sensor output signal changing with the voltage across the circuit breaker in the system embodiment of the application for measuring the uneven distribution coefficient of circuit breaker breaking point voltage;

[0048] Figure 6 The curve diagram of uneven distribution coefficient changing with the voltage across the circuit breaker in the system embodiment of the application for measuring the uneven distribution coefficient of circuit breaker breaking point voltage. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical scheme and advantages of the application more clear and explicit, the application is further described in detail below in combination with the drawings and examples.

[0050] System embodiment for measuring the uneven distribution coefficient of circuit breaker breaking point voltage:

[0051] The embodiment provides a technical scheme of a system for measuring the uneven distribution coefficient of circuit breaker breaking point voltage, wherein the measured circuit breaker is a double-breaking-point circuit breaker, the circuit breaker is formed by connecting two arc extinguishing chambers in series, and the two arc extinguishing chambers are in an open state, that is, each arc extinguishing chamber corresponds to a breaking point; referring to Figure 1 The measuring system comprises a first sphere (that is, sphere A in Figure 1 ), a suspension structure, a second sphere (that is, sphere B in Figure 1 ), a support structure, a sensor, a measuring module and a processor.

[0052] The suspension structure is an insulator used to suspend sphere A in the air; this suspension structure is typically a string of insulators. The support structure is also an insulator, located directly below sphere A, used to fix sphere B at a predetermined distance directly below sphere A. This predetermined distance is the distance between sphere A and sphere B, and it is related to the voltage applied to the equalizing ring end of the break during measurement. The larger the voltage applied to the equalizing ring end of the break, the larger the predetermined distance. In this embodiment, the double-break circuit breaker being measured is a ±800kV DC high-speed switch (HSS). To ensure that the gap between spheres A and B is not broken down when a certain high voltage is applied to the ±800kV HSS, thereby protecting the oscilloscope and measuring device, the predetermined distance is set within the range of 0.7m-1.5m. In other embodiments, the predetermined distance can also be adaptively adjusted according to the principle that "the larger the voltage applied to the equalizing ring end of the break, the larger the predetermined distance."

[0053] Sphere A is a conductor used to connect to the triple box of the double-break circuit breaker via a wire; since sphere A is suspended in the air, in order to save costs and avoid the impact of the weight of sphere A on safety, sphere A is designed as a hollow spherical shell structure.

[0054] Sphere B is a conductor with a hollow structure, used for grounding; the sensor is placed inside the hollow structure of sphere B, as a reference. Figure 2a The sensor includes an opening cover, a rotating blade, a rotating shaft for the rotating blade, and a motor. The rotating blade is positioned between the opening cover and the motor. In this embodiment, the distance between the rotating blade and the opening cover is only about 1 mm. The rotating blade is connected to the motor via the rotating shaft. The motor is used to control the rotating blade to rotate at a set speed. Specifically, it is connected to the rotating shaft of the rotating blade through an insulator, which drives the rotating shaft to rotate, thereby causing the rotating blade to rotate. The opening cover and the rotating blade are both positioned on the connecting line between the centers of the first sphere and the second sphere. That is, the connecting line between the centers of sphere A and sphere B passes perpendicularly through the center of the opening cover and the rotating blade.

[0055] The measurement module includes a measuring device and a conversion resistor, which correspond to... Figure 2a The embodiment includes an oscilloscope and a resistor; the conversion resistor is used to convert the alternating current generated on the rotating blade into a voltage across its terminals, and the measuring device is used to measure this voltage value and use it as the measurement result; in this embodiment, the measuring device is an oscilloscope, which also corresponds to... Figure 1 The recording instrument in the middle; to ensure that the measured voltage value on the conversion resistor is within a reasonable range, the motor speed is controlled to approximately 2000 r / min in this embodiment; such as Figure 2aAs shown, a rotating shaft of the rotating blade is pressed with a spring, which can ensure that the wire is tightly connected with the rotating shaft, but does not affect the normal rotation of the rotating shaft (in other embodiments, other fixing methods can also be used, as long as the wire is tightly connected with the rotating shaft and does not affect the normal rotation of the rotating shaft). The wire is connected to one end of the conversion resistor, and the other end of the conversion resistor is grounded through another wire; the two measuring lines of the oscilloscope are connected at the two ends of the conversion resistor, that is, the oscilloscope is connected in parallel with the conversion resistor; thus, the voltage value at the conversion resistor can be accurately obtained through the measuring device.

[0056] Wherein, the open cover is arranged on the surface of the top of the second sphere, and the rotating blade is arranged in the internal space of the second sphere, and the internal space is surrounded by the open cover and the inner wall of the second sphere; that is, in order to place the sensor, a hollow is dug out on the surface of the lower half of the sphere B, the opening is directed to the position of the sphere A, and the rotating blade and the motor of the sensor are placed in the hollow, and the opening is covered by the open cover; as Figure 2a As shown, in this embodiment, the sphere B is a hollow structure, that is, the sphere B is a shell, and the motor is fixed on the shell through a plurality of insulating supports; in other embodiments, other shapes and sizes of hollow structures can also be arranged, as long as enough space can be reserved for arranging the motor, the rotating blade, the conversion resistor, the measuring line between the conversion resistor and the oscilloscope, and the wire of the motor power supply.

[0057] The rotating shaft direction of the rotating blade is consistent with the connecting line direction between the centers of the first sphere and the second sphere, and the area of the rotating blade blocked by the open cover changes with the position of the rotating blade; in this embodiment, the number of the openings on the open cover is the same as the number of the rotating blades, and the positions of the openings on the open cover correspond to the positions of the rotating blades respectively; and the number of the openings and the number of the rotating blades are both even, which are 6, 8 or 12.

[0058] Referring to Figure 2b , the open cover has a fan-shaped hole, Figure 2bThe black part in the figure is the open-hole cover plate entity part, and the white part is the hole opened on the cover plate; in this embodiment, the shape of the rotating blade can ensure that it can be completely exposed from each hole without being blocked when it is rotated to the fan-shaped hole; when the rotating blade is turned to the position coinciding with the hole, the area increases, the open-hole cover plate cannot block the rotating blade or the proportion of the area of the rotating blade blocked by the open-hole cover plate to the total area of the rotating blade decreases, and the electric charge on the blade changes from less to more; in this embodiment, when the open-hole cover plate cannot block the rotating blade, the electric charge on the blade reaches the maximum value; when the rotating blade is turned to the position coinciding with the hole, the area decreases, the open-hole cover plate completely blocks or the proportion of the area of the rotating blade blocked by the open-hole cover plate to the total area of the rotating blade increases, and the electric charge on the blade changes from more to less; in this embodiment, when the open-hole cover plate completely blocks the rotating blade, the electric charge on the blade reaches the minimum value; according to the above process, it can be seen that, with the rotation of the blade driven by the motor, the electric charge on the blade will change alternately from more to less and then to more; the increase and decrease of the electric charge on the blade will generate an alternating current; the alternating current is converted into a voltage through the conversion resistor in the measurement module, and then the voltage measured by the oscilloscope is converted into the actual voltage value of the triple box, so as to realize the measurement of the voltage at the triple box; the structures of the above-mentioned sphere A, sphere B and sensor are equivalent to directly measuring the fracture voltage through the sphere gap induction principle, so that the influence of factors such as partial discharge, surrounding equipment corona, circuit breaker support and the like on the fracture voltage distribution can be excluded; and the measured circuit breaker fracture and the main part of the measurement sphere gap are non-contact, which can avoid introducing a parallel resistance-capacitance circuit and affecting the accuracy of voltage distribution measurement.

[0059] The measurement device, i.e., the oscilloscope, is arranged on the ground at the position of the support structure for supporting the sphere B, so as to facilitate observing and recording the data transmitted by the sensor at any time; the electric signal output obtained from the sensor is transmitted to the oscilloscope through a 15 m signal cable (measurement line) for observation; since in a high-voltage environment, if the detection result of the measurement module is transmitted through a cable, the electric signal will be attenuated during the transmission process, resulting in inaccurate measurement results, therefore, the measurement module is arranged on the ground at the position of the support structure, which can avoid attenuation to the greatest extent; in other embodiments, an electro-optical conversion device can be used to convert the measured electric signal into an optical signal and then transmit it through an optical cable, at this time, the attenuation problem does not need to be considered, and the measurement module can be arranged at any position that does not affect other measurement steps.

[0060] In this embodiment, the lead connecting the sphere A and the triple box of the double-break circuit breaker, the power line and the control line corresponding to the sensor, the controller corresponding to the motor and the measurement device are all sleeved with an aluminum foil bellows, which can play a shielding protection role against interference; such a bellows also has the advantages of light weight, arbitrary bending and straightening, easy installation, oil resistance, corrosion resistance, aging resistance, high temperature resistance and the like.

[0061] The processor is configured to execute program instructions to implement the following circuit breaker voltage distribution unevenness coefficient measurement steps:

[0062] 1) a voltage value U of a set size is applied to the grading ring end of one of the two breaking points (i.e. breaking point A in Figure 1 ), and the voltage across the two breaking points of the double breaking point circuit breaker is U, and the grading ring end of the other breaking point (i.e. breaking point B in Figure 1 ) is grounded; Figure 1

[0063] The suspended sphere A is connected to the triple box through a wire, and since the resistance between the two sphere gaps is infinite, although the sphere gap is connected in parallel with the breaking point B, it will not reduce the resistance value on the breaking point and cause measurement errors; since the voltage applied to the breaking point A is the total voltage, and the breaking point B is grounded, the voltage across the breaking point B and the triple box is the actual voltage value at the triple box, and since the sphere gap is connected in parallel with the breaking point B, the actual voltage value between the sphere A and the sphere B measured is the actual voltage value between the sphere A and the sphere B.

[0064] 2) the motor is controlled to be turned on, the alternating current generated on the rotating blade is converted into a voltage across the conversion resistor, the voltage value is measured by the oscilloscope, and the actual voltage value between the first sphere and the second sphere is obtained according to the calibration conversion relationship, as the voltage value borne by the breaking point with the grading ring end grounded;

[0065] When the measurement device is an oscilloscope, the voltage signal converted from the alternating current generated on the rotating blade is obtained from the oscilloscope, as shown in Figures 4a-4d , respectively, the actual voltage signal at the triple box output by the sensor when the voltage value of 108 kV, 198 kV, 301 kV and 401 kV is applied to the grading ring end of the breaking point A; Figures 4a-4d

[0066] The calibration conversion relationship needs to be obtained through a calibration experiment before the circuit breaker voltage distribution unevenness coefficient measurement steps are performed; in this embodiment, the processor is further configured to execute program instructions to implement the following calibration experiment process:

[0067] ±800kV HSS is grounded at both ends, and high voltage is directly applied to the triple box; the high voltage on the triple box is increased from 100 kV, and 1 set of data is measured by the measurement module for each increase of 50 kV, and 6 sets of data are recorded when the voltage is increased to 300 kV, and the curve corresponding to the actual value (theoretical value) of the voltage at the triple box and the amplitude of the voltage signal at the triple box measured by the measurement device (the measurement value output by the measurement module) is taken as the calibration conversion relationship curve, as shown in Figure 3 ​​As shown, the linearity of the calibration conversion curve is very good, indicating that the measurement method has high accuracy and can accurately calculate the actual voltage value based on the measurement signal. According to the calibration conversion curve or the corresponding conversion formula, the amplitude of the voltage signal at the three-cell box measured by the measuring device can be converted into the actual voltage value at the three-cell box, that is, the actual voltage value between sphere A and sphere B is obtained, which is denoted as U1 here.

[0068] 3) The voltage non-uniformity coefficient of the circuit breaker is calculated based on the voltage applied to the equalizing ring end of the break and the voltage borne by the break where the equalizing ring end is grounded.

[0069] According to steps 1) and 2), the voltage applied to the equalizing ring end of the fracture is U, and the actual voltage between sphere A and sphere B is U1; since fracture B is connected in parallel with the sphere gap, the voltage borne by fracture B is also U1, then the voltage borne by fracture A is U2 = U - U1.

[0070] The principle for calculating the non-uniformity coefficient of voltage distribution at the break point is as follows:

[0071]

[0072] The voltage distribution non-uniformity coefficient at the break point can then be calculated using the following formula:

[0073]

[0074] In the formula, f is the voltage non-uniformity coefficient of the circuit breaker, U is the voltage value applied to the equalizing ring end of the circuit breaker, U1 is the voltage value borne by the circuit breaker with the equalizing ring end grounded, and U2 is the voltage value borne by the circuit breaker with the voltage applied to the equalizing ring end.

[0075] After applying voltage to the equalizing ring terminal of HSS at break point A, three measurements are performed for each voltage level, and the average value of the output signal amplitude of the measurement module is calculated. The relationship between the output signal amplitude of the measurement device (the measured value output by the measurement device) and the voltage applied to the equalizing ring terminal of HSS at break point A is obtained as follows: Figure 5 As shown; by Figure 5 It can be seen that the amplitude of the output signal of the measuring device is basically linearly related to the DC voltage applied to the equalizing ring end of HSS break point A.

[0076] The measured value output by the measuring device is converted into the actual voltage value U1 at the triple box according to the calibration conversion relationship. Then, the voltage distribution non-uniformity coefficient of the break point A corresponding to different voltage values ​​applied to the equalizing ring end is calculated by the formula, as shown in Table 1:

[0077] Table 1. Measured voltage of the circuit breaker's triple-unit box.

[0078]

[0079] Using the different voltage values ​​(voltages across the circuit breaker) applied to the equalizing ring of HSS break point A as the x-axis and the calculated voltage distribution non-uniformity coefficient as the y-axis, a curve showing the variation of the voltage distribution non-uniformity coefficient with voltage is plotted as follows: Figure 6 As shown; by Figure 6 It can be seen that when the voltage across the circuit breaker is less than 250kV, the calculated voltage distribution non-uniformity coefficient at the break point is greater than 1.3 and the dispersion is relatively large; when the voltage is in the range of 250 to 500kV, the voltage distribution non-uniformity coefficient at the break point is between 1.2 and 1.3; when the voltage exceeds 500kV, the distribution of the voltage distribution non-uniformity coefficient at the break point is relatively concentrated and tends to be stable, with the voltage distribution non-uniformity coefficient at the break point stabilizing between 1.25 and 1.27.

[0080] Example of a method for measuring the non-uniformity coefficient of voltage distribution at circuit breaker points:

[0081] This embodiment provides a technical solution for measuring the voltage distribution non-uniformity coefficient of a circuit breaker. The measurement is achieved using the measurement system described in the above embodiment of the system for measuring the voltage distribution non-uniformity coefficient of a circuit breaker. The measurement steps are as follows:

[0082] 1) Apply a set voltage value to the equalizing ring terminal of one of the breaks of the double-break circuit breaker, and ground the equalizing ring terminal of the other break.

[0083] 2) Control the motor to start, and convert the alternating current generated on the rotating blade into the voltage across the resistor through the conversion resistor. Measure the voltage value with an oscilloscope, and obtain the actual voltage value between the first and second spheres according to the calibration conversion relationship. This voltage value is used as the voltage value borne by the grounding break of the equalizing ring.

[0084] 3) The voltage non-uniformity coefficient of the circuit breaker is calculated based on the voltage applied to the equalizing ring end of the break and the voltage borne by the break where the equalizing ring end is grounded.

[0085] Since the specific principles, structure, and working process of the measurement system have been described in detail in the above-mentioned system embodiment for measuring the non-uniformity coefficient of circuit breaker voltage distribution, they will not be repeated here.

[0086] This invention has the following characteristics:

[0087] ① Apply a DC voltage to one side of the double-break circuit and ground the other side. One of the breaks and the ball gap form a parallel circuit. The voltage of the break is directly measured by induction through the ball gap, eliminating the influence of partial discharge, corona discharge of surrounding equipment, circuit breaker support and other factors on the voltage distribution of the break. It is also ensured that the circuit breaker break being measured and the main body of the measuring ball gap are non-contact, which can avoid the introduction of parallel RC circuit and avoid affecting the accuracy of voltage distribution measurement.

[0088] ②The electric field sensor is arranged inside the sphere, which can directly convert the electric field value into the voltage value at the two ends of one of the fracture, so as to calculate the fracture voltage uneven coefficient. The distance between the sphere gaps is fixed when the voltage is measured, so it is not necessary to adjust or use the sphere gap breakdown to obtain the voltage value. The measurement voltage can be adjusted more simply and flexibly, so the measurement efficiency can be improved.

[0089] ③The lead wire connecting the first sphere and the triple box of the double fracture circuit breaker, the power line and the control line corresponding to the sensor, the controller corresponding to the motor and the measuring module are all sleeved with aluminum foil corrugated pipes, which can play a shielding protection role against interference. The measuring module is arranged on the ground near the position of the support structure, which can maximize the attenuation of the output electric signal of the measuring module.

[0090] It should be understood that any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present application shall be included in the protection scope of the present application.

Claims

1. A system for measuring the voltage distribution non-uniformity coefficient of a circuit breaker, wherein the circuit breaker is a double-break circuit breaker, characterized in that, The system includes a first sphere, a suspension structure, a second sphere, a support structure, sensors, a measurement module, and a processor; The suspension structure is an insulator used to suspend the first sphere in the air. The support structure is also an insulator and is located directly below the first sphere to fix the second sphere at a predetermined distance directly below the first sphere. The first sphere is a conductor, used to connect to the triple box of the double-break circuit breaker via a wire; The second sphere is a conductor with a cavity structure for grounding; the sensor includes an opening cover, a rotating blade, a rotating shaft and a motor, with the rotating blade disposed between the opening cover and the motor; The rotating blade is connected to the motor via a rotating shaft, and the motor is used to control the rotating blade to rotate at a set speed via the rotating shaft. Both the perforated cover and the rotating blade are disposed on the connecting line between the centers of the first sphere and the second sphere; wherein, the perforated cover is disposed on the surface of the second sphere, and the rotating blade is disposed in the internal space of the second sphere, the internal space being enclosed by the inner walls of the perforated cover and the second sphere; the rotation axis direction of the rotating blade is consistent with the direction of the connecting line between the centers of the first sphere and the second sphere, and the area of ​​the rotating blade covered by the perforated cover changes with the rotation position of the rotating blade; The measurement module includes a measuring device and a conversion resistor; one end of the conversion resistor is connected to the rotating shaft via a wire, and the other end is grounded, which is used to convert the alternating current generated on the rotating blade into a voltage across the conversion resistor; the measuring device is connected in parallel with the conversion resistor, which is used to measure the voltage across the conversion resistor, and the voltage across the conversion resistor is used as the measurement result of the measuring device. The processor is used to execute program instructions to implement the following steps for measuring the non-uniformity coefficient of circuit breaker voltage distribution: 1) Apply a set voltage value to the equalizing ring terminal of one of the breaks of the double-break circuit breaker, and ground the equalizing ring terminal of the other break; 2) Control the motor to start, convert the alternating current generated on the rotating blade into the voltage across the resistor through the conversion resistor, obtain the voltage through the measuring device, and obtain the actual voltage value between the first sphere and the second sphere according to the calibration conversion relationship, which is used as the voltage value borne by the grounding break of the equalizing ring. 3) The voltage non-uniformity coefficient of the circuit breaker is calculated based on the voltage applied to the equalizing ring end of the break and the voltage borne by the break where the equalizing ring end is grounded.

2. The system for measuring the non-uniformity coefficient of circuit breaker voltage distribution according to claim 1, characterized in that, The formula for calculating the coefficient of non-uniformity of fracture surface is: U2=U-U1 In the formula, f is the voltage non-uniformity coefficient of the circuit breaker, U is the voltage value applied to the equalizing ring end of the circuit breaker, U1 is the voltage value borne by the circuit breaker with the equalizing ring end grounded, and U2 is the voltage value borne by the circuit breaker with the voltage applied to the equalizing ring end.

3. The system for measuring the non-uniformity coefficient of circuit breaker voltage distribution according to claim 1 or 2, characterized in that, The calibration conversion relationship is obtained by directly applying voltage to the triple box, with the equalizing rings of both breaks grounded, and obtaining the correspondence between the voltage value applied to the triple box and the voltage value measured by the measuring device. This correspondence serves as the calibration conversion relationship between the actual voltage value between the first and second spheres and the voltage value measured by the measuring device.

4. The system for measuring the non-uniformity coefficient of circuit breaker voltage distribution according to claim 1 or 2, characterized in that, The set distance is related to the voltage applied to the equalizing ring end of the fracture. The greater the voltage applied to the equalizing ring end of the fracture, the greater the set distance.

5. The system for measuring the non-uniformity coefficient of circuit breaker voltage distribution according to claim 1 or 2, characterized in that, The first sphere and / or the second sphere are hollow spherical shell structures.

6. The system for measuring the non-uniformity coefficient of circuit breaker voltage distribution according to claim 1 or 2, characterized in that, The number of holes on the perforated cover plate is the same as the number of rotating blades, and the positions of the holes on the perforated cover plate correspond to the positions of each rotating blade; and the number of holes and the number of rotating blades are both even numbers.

7. The system for measuring the non-uniformity coefficient of circuit breaker voltage distribution according to claim 1 or 2, characterized in that, The measuring device is set on the ground at the location of the support structure.

8. The system for measuring the non-uniformity coefficient of circuit breaker voltage distribution according to claim 1 or 2, characterized in that, The wires connecting the first ball to the triple box of the double-break circuit breaker, the power and control lines corresponding to the sensor, the controller corresponding to the motor, and the measuring device are all covered with aluminum foil corrugated pipes.

9. The system for measuring the non-uniformity coefficient of circuit breaker voltage distribution according to claim 7, characterized in that, The conversion resistor is disposed in the internal space of the second sphere.

10. A method for measuring the non-uniformity coefficient of voltage distribution at the circuit breaker break point, characterized in that, The measurement is performed using the system for measuring the non-uniformity coefficient of voltage distribution at the circuit breaker junction as described in any one of claims 1-9, and the measurement steps are as follows: 1) Apply a set voltage value to the equalizing ring terminal of one of the breaks of the double-break circuit breaker, and ground the equalizing ring terminal of the other break; 2) Control the motor to start, convert the alternating current generated on the rotating blade into the voltage across the resistor through the conversion resistor, obtain the voltage through the measuring device, and obtain the actual voltage value between the first sphere and the second sphere according to the calibration conversion relationship, which is used as the voltage value borne by the grounding break of the equalizing ring. 3) The voltage non-uniformity coefficient of the circuit breaker is calculated based on the voltage applied to the equalizing ring end of the circuit breaker and the voltage borne by the circuit breaker with the equalizing ring end grounded.

Images