Device and method for detecting insulation state of power transformer

Abstract

The invention relates to the field of power transformer insulation performance testing, in particular to a power transformer insulation state detection device and method. The power transformer insulation state detection device comprises a frame, and a high-voltage DC generator, an ammeter, a current-limiting resistor, a first switch, a sampling resistor, a charging capacitor, a wave modulation inductor, a signal output port and a signal input port which are arranged on the frame and are sequentially connected in series, the voltage of the high-voltage direct-current generator, the size of the current-limiting resistor, the size of the wave modulation inductor and the size of the charging capacitor can be adjusted; the signal output port and the signal input port are used for accessing a transformer winding; one end of the second switch is connected with the zero voltage point, and the other end is connected between the first switch and the sampling resistor. According to the invention, the operation process of high-voltage oscillation wave detection on the power transformer is simplified, the error probability of manual operation is reduced, and the efficiency of high-voltage oscillation wave detection on the power transformer is improved.

Description

Technical Field

[0001] The invention relates to the field of power transformer insulation performance testing, and in particular to a power transformer insulation state detection device and a detection method. Background Art

[0002] As the scale of the power system continues to expand, the safe and reliable operation of power transformers, as key equipment for power transmission and distribution, is of vital importance. The insulation performance of transformers will gradually deteriorate when they operate in a complex electrical environment for a long time. Once the insulation fails, it may cause a power outage, which will have a serious impact on production and life. Therefore, accurate and efficient detection of transformer insulation performance has become a key requirement to ensure the stable operation of the power system.

[0003] Among them, the traditional insulation detection method has certain limitations, specifically: Although the traditional DC withstand voltage test can detect some insulation defects, it cannot effectively simulate the AC voltage stress that the transformer is subjected to in actual operation, and it is difficult to accurately detect some insulation weaknesses that are only exposed under AC electric fields. For example, when testing transformers with oil-paper insulation structures, phenomena such as charge accumulation at the oil-paper interface under DC voltage are quite different from those under AC conditions, and detection blind spots are prone to occur.

[0004] Although the AC withstand voltage test is closer to the actual operating conditions, it requires a large-capacity test power supply and is difficult to implement on-site. Especially for some transformers installed in remote areas where it is difficult to obtain large-capacity power supplies, the test cost is high and the operation is inconvenient, which limits its widespread application.

[0005] High-voltage oscillation wave detection technology came into being. It can simulate the AC voltage characteristics that the transformer is actually subjected to during operation to a certain extent. At the same time, compared with the traditional AC withstand voltage test, the requirements for the test power supply capacity are relatively low, which facilitates on-site testing.

[0006] In the prior art, when performing high-voltage oscillation wave testing, operators are required to connect and debug multiple different instruments and equipment. Due to the lack of integrated test equipment that can directly perform high-voltage oscillation wave testing, the operation process is cumbersome and prone to errors. Summary of the invention

[0007] The purpose of the present invention is to provide a power transformer insulation state detection device, which simplifies the operation process of high-voltage oscillation wave detection on the power transformer, reduces the probability of human operation errors, and improves the efficiency of high-voltage oscillation wave detection on the power transformer. The present application also provides a power transformer insulation state detection method, which is implemented by the power transformer insulation state detection device and is used to improve the efficiency of high-voltage oscillation wave detection on the power transformer.

[0008] In order to solve the above problems, the present invention provides a device and method for detecting the insulation status of a power transformer.

[0009] The power transformer insulation state detection device of the present invention comprises a frame and a high-voltage DC generator, an ammeter, a current limiting resistor, a first switch, a sampling resistor, a charging capacitor, a wave modulation inductor, a signal output port and a signal input port which are arranged on the frame and connected in series in sequence; the voltage of the high-voltage DC generator, the magnitude of the current limiting resistor, the magnitude of the wave modulation inductor and the magnitude of the charging capacitor are adjustable; The signal output port and the signal input port are used to connect to the transformer winding; It also includes an interlock switch, the interlock switch includes a second switch and a third switch, one end of the second switch is connected to the zero voltage point, and the other end is connected between the first switch and the sampling resistor; The third switch is connected in parallel with the current limiting resistor, the first switch, the sampling resistor, the charging capacitor and the modulating inductor.

[0010] Furthermore, the modulated inductor includes a probe, an inductor winding and a winding height adjustment component, one end of the probe is fixed on the frame, and the other end abuts the inductor winding, and the winding height adjustment component is used to adjust the height of the inductor winding and thereby adjust the abutment position of the probe.

[0011] Furthermore, the winding height adjustment assembly includes an upper chassis, a lower chassis and a plurality of telescopic columns, the lower chassis is fixed on the frame, the upper chassis is fixed to the bottom of the inductor winding, one end of the plurality of telescopic columns is connected to the lower chassis, and the other end is connected to the upper chassis.

[0012] Further, the second switch includes a first shell and a contactor assembly arranged on the first shell, the third switch includes a second shell and a contactor assembly arranged on the second shell, the first shell and the second shell are arranged in parallel and spaced apart, and the interlock switch also includes a contact ball, which is used to be placed on the first shell or the second shell and contact with the contactor assembly to close the second switch or the third switch.

[0013] Furthermore, the interlock switch further comprises a clamping mechanism, which is disposed on the frame and is used to clamp the contact ball and place the contactor on the first housing or the second housing.

[0014] Furthermore, the clamping mechanism includes a front-to-back moving component, a left-to-right moving component, an up-and-down moving component and a clamping arm, the front-to-back moving component is arranged on the frame, the left-to-right moving component is arranged on the front-to-back moving component, the up-and-down moving component is arranged on the left-to-right moving component, and the clamping arm is arranged on the up-and-down moving component.

[0015] Further, the charging capacitor includes a first capacitor component, a second capacitor component and a rotating motor, the first capacitor component includes a fixed shaft and a plurality of first capacitor plates arranged on the fixed shaft, the fixed shaft is fixed to the frame, the second capacitor component includes a rotating shaft and a plurality of second capacitor plates arranged on the rotating shaft, the plurality of first capacitor plates and the plurality of second capacitor plates are arranged alternately one by one, the rotating shaft is rotatably arranged on the frame, and the rotating motor is used to drive the rotating shaft to rotate a set angle to adjust the overlapping area of ​​the projections of the first capacitor plates and the second capacitor plates on the circumferential direction of the rotating shaft.

[0016] Furthermore, it also includes a display screen fixed on the frame, and the display screen is used to display the reading of the ammeter.

[0017] The present invention also provides a method for detecting the insulation state of a power transformer, which is implemented by the device for detecting the insulation state of a power transformer described in any one of the above technical solutions, comprising: Step S100: selecting the required resistance value of the current limiting resistor, the inductance value of the modulating inductor and the capacitance value of the charging capacitor; Step S200: Connect one end of the transformer winding to the signal output port, and the other end to the signal input port; Step S300: enabling the high voltage DC generator to output a required voltage; Step S400: closing the first switch to charge the charging capacitor, and opening the first switch after the charging capacitor is fully charged; Step S500: closing the second switch and collecting the oscillation wave signal; Step S600: extracting a signal characteristic value according to the oscillation wave signal; Step S700: performing fault diagnosis on transformer windings according to the signal characteristic values.

[0018] Furthermore, if the signal characteristic value is greater than or equal to a first set value, the transformer winding is severely deformed and cannot be used; if the signal characteristic value is less than the first set value and greater than or equal to a second set value, the transformer winding is obviously deformed and cannot be used; if the signal characteristic value is less than the second set value and greater than 0, the transformer winding is slightly deformed or not deformed and can be used normally.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects: The power transformer insulation state detection device of the present application is provided with a high-voltage DC generator, an ammeter, a current limiting resistor, a first switch, a sampling resistor, a charging capacitor, a wave modulation inductor, a signal output port and a signal input port and other structures, and integrates the high-voltage oscillation wave generation, voltage and current parameter measurement, switch control and related mechanical structures into the detection device, so as to realize one-stop operation from wiring, test start, data collection to test end. The operator does not need to go back and forth between multiple instruments and equipment for connection and debugging, which simplifies the operation process of high-voltage oscillation wave detection on the power transformer, reduces the probability of human operation errors, and improves the efficiency of high-voltage oscillation wave detection on the power transformer.

[0020] The power transformer insulation state detection device of the present application can be used to detect the insulation state of the power transformer, such as analyzing leakage current changes, observing oscillation waveform characteristics, etc., so as to achieve a more accurate assessment of the insulation condition of the transformer.

[0021] The power transformer insulation state detection method of the present application is implemented through the power transformer insulation state detection device, which can simplify the operation process of high-voltage oscillation wave detection on the power transformer, reduce the probability of human operation errors, and improve the efficiency of high-voltage oscillation wave detection on the power transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural schematic diagram of an embodiment of a device for detecting insulation status of a power transformer of the present invention; Figure 2 for Figure 1 A schematic structural diagram of another perspective of the power transformer insulation state detection device; Figure 3 A circuit wiring diagram of an embodiment of a power transformer insulation state detection device of the present invention; Figure 4 for Figure 1 A schematic diagram of the structure of a clamping mechanism of a power transformer insulation state detection device; Figure 5 for Figure 4 A structural schematic diagram of the clamping mechanism from another perspective; Figure 6 for Figure 1 A schematic diagram of the structure of the power transformer insulation state detection device with part of the structure hidden; Figure 7 for Figure 1 A schematic structural diagram of the power transformer insulation state detection device from another perspective with part of the structure hidden; Figure 8A flow chart of an embodiment of a method for detecting insulation status of a power transformer of the present invention; Fig. 9 An oscillation waveform diagram of a high-voltage winding of a power transformer obtained by using the power transformer insulation state detection device of the present invention; Fig.10 The oscillation waveform diagram of the medium voltage winding of the power transformer obtained by using the power transformer insulation state detection device of the present invention; Fig.11 The figure is an oscillation waveform diagram of the low-voltage winding of the power transformer obtained by using the power transformer insulation state detection device of the present invention.

[0023] Reference numerals: 110, frame; 111, support plate; 112, support column; 113, bottom beam; 114, top beam; 115, signal output port; 116, signal input port; 117, foot pad; 118, fixed column; 119, sampling resistor; 210, first switch; 211, left support base; 212, right support base; 213, contact head; 214, telescopic head; 215, traction winding; 221, second switch; 222, third switch; 223, first housing; 224, second housing; 225, contact ball; 226, support ear; 227, front contactor; 228, rear contactor; 230, wave modulation inductor; 231, probe; 232, inductor winding; 233, upper chassis; 234, lower chassis; 235, telescopic column; 300, gripping mechanism; 310, front and rear moving assembly; 311, front and rear guide rails; 312, front and rear moving frame; 313, front and rear driving motors; 320, left and right moving components; 321, left and right guide rails; 322, left and right moving frames; 323, left and right driving motors; 330, up and down moving assembly; 331, up and down guide rails; 332, up and down moving frame; 333, up and down driving motors; 334, mounting frame; 335, lead screw; 360, clamping arm; 410. Rotating electrical machines; 421, fixed axis; 422, first capacitor plate; 423, fixed plate; 431, a rotating shaft; 432, a second capacitor plate; 510, power socket; 520, power block; 530, display light; 540, knob switch; 610, resistor rod; 620, supporting cross bar; 630, resistor contact clip; 640, resistor slider; 700. Display screen. DETAILED DESCRIPTION

[0024] The following will describe the power transformer insulation state detection device and detection method of the present invention in conjunction with the schematic diagram, wherein the preferred embodiment of the present invention is shown, and it should be understood that those skilled in the art can modify the present invention described herein, and still achieve the beneficial effects of the present invention. Therefore, the following description should be understood as being widely known to those skilled in the art, and not as a limitation of the present invention.

[0025] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in very simplified form and are not in exact proportions, and are only used to facilitate and clearly assist in illustrating the purpose of the embodiments of the present invention.

[0026] The following is attached to the instruction manual Figure 1 To Attachment Fig.11 , a power transformer insulation status detection device and detection method of the present invention are described.

[0027] In one embodiment, the structure diagram of the power transformer insulation state detection device is as follows: Figure 1 , Figure 2 and Figure 6 As shown, the circuit wiring diagram is as follows Figure 3 As shown, it includes a frame 110 and a high-voltage DC generator, an ammeter, a current limiting resistor, a first switch 210, a sampling resistor 119, a charging capacitor, a wave modulation inductor 230, a signal output port 115 and a signal input port 116 arranged on the frame 110 and connected in series in sequence; the voltage of the high-voltage DC generator, the size of the current limiting resistor, the size of the wave modulation inductor 230 and the size of the charging capacitor are adjustable. In this embodiment, the ammeter is a microammeter, and in other embodiments, the ammeter can also be other types of meters.

[0028] The signal output port 115 and the signal input port 116 are used to access transformer windings.

[0029] It also includes an interlock switch, which includes a second switch 221 and a third switch 222. One end of the second switch 221 is connected to the zero voltage point, and the other end is connected between the first switch 210 and the sampling resistor 119. The zero voltage point may be a grounding point.

[0030] The third switch 222 is connected in parallel with the current limiting resistor, the first switch 210 , the sampling resistor 119 , the charging capacitor and the modulating inductor 230 .

[0031] Specifically, the frame 110 is a rectangular frame 110, and the frame 110 includes a support plate 111, a support column 112, a fixed column 118, a bottom beam 113 and a top beam 114. The support plate 111 is located at the lower part of the frame 110, and is surrounded by four bottom beams 113. There are four support columns 112, and there are two fixed columns 118 that are parallel to the support columns 112. The upper end of the support column 112 is provided with four top beams 114 connected end to end.

[0032] The high-voltage direct current generator, the sampling resistor 119 , the first switch 210 , the second switch 221 , the third switch 222 , the modulating inductor 230 , the signal input port 116 and the signal output port 115 are all disposed on the support plate 111 .

[0033] Four foot pads 117 are further provided at the bottom of the bottom cross beam 113 . The foot pads 117 are preferably made of insulating material, which can protect the test site on the one hand, and have the function of shock absorption and noise reduction on the other hand.

[0034] In one embodiment, if Figure 6 As shown, in order to facilitate the adjustment of the inductance value of the wave modulation inductor 230 connected to the circuit, the wave modulation inductor 230 includes a probe 231, an inductor winding 232 and a winding height adjustment component. One end of the probe 231 is fixed to the fixed column 118 of the frame 110, and the other end is abutted against the inductor winding 232. The winding height adjustment component is used to adjust the height of the inductor winding 232 and thus adjust the abutment position of the probe 231.

[0035] Specifically, the winding height adjustment assembly includes an upper chassis 233, a lower chassis 234 and a plurality of telescopic columns 235, wherein the lower chassis 234 is fixed to the frame 110, the upper chassis 233 is fixed to the bottom of the inductor winding 232, and one end of the plurality of telescopic columns 235 is connected to the lower chassis 234, and the other end is connected to the upper chassis 233. The telescopic columns 235 may be electric push rods or hydraulic push rods.

[0036] In order to improve the flexibility of adjustment, the telescopic column 235 and the upper chassis 233 are hinged by a ball joint, and the telescopic column 235 and the lower chassis 234 are also hinged by a ball joint, so that the inductor winding 232 can move up and down and tilt at a certain angle.

[0037] In one embodiment, if Figure 6 and Figure 7As shown, the second switch 221 includes a first shell 223 and a contactor assembly arranged on the first shell 223, the third switch 222 includes a second shell 224 and a contactor assembly arranged on the second shell 224, the first shell 223 and the second shell 224 are arranged in parallel and spaced apart, and the interlock switch also includes a contact ball 225, which is used to be placed on the first shell 223 or the second shell 224 and contact with the contactor assembly to close the second switch 221 or the third switch 222.

[0038] Specifically, the first shell 223 and the second shell 224 have the same structure, both having a bottom box body and two supporting ears 226 located on the bottom box body, the contact ball 225 is an ellipsoidal structure made of conductive material, with cylindrical sections at both ends, and the two supporting ears 226 both have supporting grooves to support the cylindrical sections at both ends of the contact ball 225, and the contactor assembly is also arranged in the bottom box body, and the contactor assembly includes a front contactor 227 and a rear contactor 228. When the contactor is placed on the supporting ears 226, the outer peripheral surface of the contact ball 225 is in contact with the front contactor 227 and the rear contactor 228 at the same time, thereby closing the corresponding switch.

[0039] In order to facilitate the movement of the contact ball 225 to close or open the second switch 221 or the third switch 222, the interlock switch also includes a clamping mechanism 300, which is arranged on the frame 110 and is used to clamp the contact ball 225 and place the contactor on the first shell 223 or the second shell 224.

[0040] Specifically, Figure 4 and Figure 5 As shown, the clamping mechanism 300 includes a front-to-back moving component 310, a left-to-right moving component 320, an up-and-down moving component 330 and a clamping arm 360, wherein the front-to-back moving component 310 is arranged on the frame 110, the left-to-right moving component 320 is arranged on the front-to-back moving component 310, the up-and-down moving component 330 is arranged on the left-to-right moving component 320, and the clamping arm 360 is arranged on the up-and-down moving component 330.

[0041] Wherein, the front-to-back moving assembly 310 comprises a front-to-back guide rail 311, a front-to-back slider, a front-to-back moving frame 312 and a front-to-back driving assembly, wherein the front-to-back guide rail 311 is arranged on the top crossbeam 114, the front-to-back slider and the front-to-back driving assembly are arranged on the front-to-back moving frame 312, and the front-to-back driving assembly can drive the front-to-back slider to slide along the front-to-back guide rail 311, thereby moving the front-to-back moving frame 312 in the front-to-back direction. The front-to-back driving member comprises a front-to-back driving motor 313, a driving gear and a driving rack, wherein the driving rack is arranged on the front-to-back guide rail 311 and meshes with the driving gear, and the front-to-back driving motor 313 is used to drive the driving gear to roll along the driving rack. The front-to-back moving frame 312 is inverted U-shaped, and its two cantilever arms are guided to slide along two mutually parallel top crossbeams 114 through the front-to-back sliders respectively.

[0042] The left-right moving assembly 320 includes left-right guide rails 321, left-right sliders, left-right moving frames 322 and left-right driving assemblies. The left-right guide rails 321 are arranged on the front-rear moving frames 312. The left-right sliders and left-right driving assemblies are arranged on the left-right moving frames 322. The left-right driving assemblies can drive the left-right moving frames 322 to slide along the left-right guide rails 321, thereby moving the left-right moving frames 322 in the left-right direction. The left-right driving member has a similar structure to the front-rear driving member, including left-right driving motors 323, driving gears and driving racks. The installation method is similar to the installation method of the left-right driving member, which will not be repeated here.

[0043] The up-and-down moving parts include up-and-down guide rails 331, up-and-down sliders, up-and-down moving frames 332, and up-and-down driving components. The up-and-down guide rails 331 are arranged on the left-and-right moving frames 322. The up-and-down sliders are arranged on the left-and-right moving frames 332. The clamping arm 360 is arranged at the end of the left-and-right moving frames 332. The up-and-down driving components can drive the up-and-down sliders to slide along the up-and-down guide rails 331, thereby moving the left-and-right moving frames 332 up and down. The up-and-down driving components include a mounting frame 334, an up-and-down driving motor 333, a lead screw 335, and a lead screw 335 nut. The lead screw nut is arranged on the left-and-right moving frames 322. The lead screw 335 cooperates with and passes through the lead screw 335 nut. The mounting frame 334 connects one end of the lead screw 335 and the left-and-right moving frames 332. The driving motor is arranged in the mounting frame 334 and can drive the lead screw 335 to rotate. When the lead screw 335 rotates, it can move in the up-and-down direction, thereby driving the left-and-right moving frames 332 to move up and down.

[0044] The clamping mechanism 300 can adjust the position of the clamping arm 360 through the forward and backward moving component 310, the left and right moving component 320 and the up and down moving component 330, so that the clamping arm 360 can accurately move the contact ball 225 to the specified position, thereby turning on or off the second switch 221 or the third switch 222.

[0045] In one embodiment, if Figure 6 and Figure 7 As shown, the charging capacitor includes a first capacitor component, a second capacitor component and a rotating motor 410, the first capacitor component includes two fixed shafts 421 and a plurality of first capacitor plates 422 arranged on the two fixed shafts 421, the fixed shaft 421 is fixed to the support column 112 and the fixed column 118 of the frame 110 through a fixed plate 423, the second capacitor component includes a rotating shaft 431 and a plurality of second capacitor plates 432 arranged on the rotating shaft 431, the fixed plate 423 is provided with a through hole for the rotating shaft 431 to pass through, the rotating shaft 431 can rotate relative to the fixed plate 423, the plurality of first capacitor plates 422 and the plurality of second capacitor plates 432 are alternately arranged one by one, the rotating shaft 431 is rotatably arranged on the frame 110, and the rotating motor 410 is used to drive the rotating shaft 431 to rotate a set angle to adjust the overlapping area of ​​the projections of the first capacitor plates 422 and the second capacitor plates 432 on the circumferential direction of the rotating shaft 431, thereby adjusting the capacitance value of the charging capacitor.

[0046] In one embodiment, if Figure 6 As shown, the high-voltage DC generator includes a power socket 510, a plurality of interconnected power blocks 520, and a plurality of display lights 530 corresponding to the power blocks 520, and also includes a knob switch 540 capable of adjusting the number of power blocks 520 connected to the circuit. When a power block 520 is connected to the circuit, the corresponding display light 530 will light up to indicate. When in use, power is first turned on through the power socket 510, and then the set number of power blocks 520 are enabled through the knob switch 540. In this embodiment, there are 8 power blocks 520, and the voltage of each power block 520 is 1000V.

[0047] In one embodiment, if Figure 5 As shown, the current-limiting resistor includes a resistor rod 610, a supporting cross bar 620, a resistor contact clamp 630 and a resistor slider 640. Two fixed columns 118 are provided in the frame 110. The resistor rod 610 extends in the horizontal direction and both ends are respectively connected to the two fixed columns 118. The supporting cross bar 620 is fixed between two top-level beams 114. The resistor contact clamp 630 and the resistor slider 640 are fixedly connected. The resistor slider 640 is guided and slidably set on the supporting cross bar 620, and the resistor contact clamp 630 is also guided and slidably set on the resistor rod 610. By moving the resistor slider 640, the position of the resistor contact clamp 630 on the resistor rod 610 can be changed, thereby adjusting the resistance value of the current-limiting resistor.

[0048] In one embodiment, if Figure 6 As shown, the first switch 210 includes a left support seat 211, a right support seat 212, a contact head 213 and a telescopic head 214, wherein the contact head 213 is fixedly arranged on the left support seat 211, and the telescopic head 214 is arranged on the right support seat 212 through a reset spring. A traction motor and a traction winding 215 are also arranged in the left support seat 211, one end of the traction winding 215 is connected to the traction motor, and the other end is connected to the telescopic head 214. When the traction motor rotates, the traction winding 215 can be wound, and the traction winding 215 drives the telescopic head 214 to overcome the resistance of the reset spring and contact the contact head 213, and the reset spring is stretched, thereby realizing the closing of the first switch 210. When the traction motor rotates in the opposite direction, under the action of the reset spring, the telescopic head 214 is reset and separated from the contact head 213, so that the first switch 210 is disconnected.

[0049] In one embodiment, in order to display the reading of the ammeter, a display screen 700 is further provided on the frame 110 .

[0050] The power transformer insulation state detection device of the present application is provided with a high-voltage DC generator, an ammeter, a current limiting resistor, a first switch 210, a sampling resistor 119, a charging capacitor, a wave modulation inductor 230, a signal output port 115 and a signal input port 116 and other structures, and integrates high-voltage oscillation wave generation, voltage and current parameter measurement, switch control and related mechanical structures into the detection device, so as to realize one-stop operation from wiring, test start, data collection to test end. The operator does not need to go back and forth between multiple instruments and equipment for connection and debugging, which simplifies the operation process of high-voltage oscillation wave detection on the power transformer, reduces the probability of human operation errors, and improves the efficiency of high-voltage oscillation wave detection on the power transformer.

[0051] The power transformer insulation state detection device of the present application can be used to detect the insulation state of the power transformer, such as analyzing leakage current changes, observing oscillation waveform characteristics, etc., so as to achieve a more accurate assessment of the transformer insulation condition.

[0052] The following describes the use of the power transformer insulation state detection device of the present application to detect the leakage current of the power transformer, which specifically includes the following steps: Step S1, selecting the required resistance value of the current limiting resistor, the inductance value of the modulating inductor 230 and the capacitance value of the charging capacitor according to the specific type and parameters of the detected power transformer; The resistance value of the current-limiting resistor is adjusted by sliding the resistor slider 640 on the support crossbar 620 to place the resistor contact clip 630 at different positions on the resistor rod 610, thereby causing the current to flow through the resistor rods 610 of different lengths; The height of the inductor winding 232 is adjusted by extending and retracting the multiple telescopic columns 235 to different lengths, thereby adjusting the contact position of the probe 231, wherein the position of the probe 231 is fixed, and the current flows into or out of the inductor winding 232 through the probe 231. When the height position of the inductor winding 232 changes, the position where the probe 231 contacts the inductor winding 232 changes, thereby changing the number of turns of the current flowing through the winding, thereby changing the inductance of the modulated inductor 230; The rotating motor 410 drives the rotating shaft 431 to rotate a set angle to adjust the overlapping area of ​​the projections of the first capacitor plate 422 and the second capacitor plate 432 on the circumferential direction of the rotating shaft 431, thereby adjusting the capacitance value of the charging capacitor.

[0053] Step S2, after one end of one of the transformer windings of the power transformer is connected to the signal output port 115, the other end is connected to the signal input port 116; the power transformer usually has three phases, and each phase has multiple transformer windings, such as a low voltage winding, a medium voltage winding and a high voltage winding, or a low voltage winding and a high voltage winding. For example, after one end of the transformer winding of the power transformer is connected to the signal output port 115, the other end is connected to the signal input port 116, and the other transformer windings are all grounded; Step S3, placing the contact ball 225 at the third switch 222 by the clamping mechanism 300 to close the third switch 222; After checking and confirming that the wiring is correct, check and confirm that the transformer windings and that no one is working nearby before proceeding with subsequent operations. During the operation, you should shout loudly to ensure safety; Step S4, operate the knob switch 540 to make the high-voltage DC generator output a suitable voltage level. During this process, the operator should put his hand near the knob switch 540 to be alert at any time and turn off the high-voltage DC generator in time when an abnormal situation occurs; Step S5, starting from turning on the knob switch 540 to output voltage, use a stopwatch to record the microammeter value I read from the display screen 700 at the 15th second, the 60th second, the 600th second, and the final stable state. 15 ,I 60 ,I 600 and I 终 In other embodiments, the values ​​of the microammeter at other time points may also be recorded, such as the 20th second, the 70th second, and the 650th second.

[0054] Among them, I 终 That is the leakage current of the transformer winding, and then according to I 15 ,I 60 ,I 60 0 and the voltage output by the high voltage DC generator to find the parameter R 60 , R60 / R 15 and R 600 / R 60 , where R 60 is the insulation resistance value, R 60 / R 15 is the absorption ratio, R 600 / R 60 These data are polarization indices that reflect the insulation condition of the transformer windings of the power transformer being tested.

[0055] It should be noted that after the experiment, the knob switch 540 is operated to turn off the high-voltage DC generator, and then the discharge rod is used to discharge the test winding and ground it. After confirming that the discharge is completed, the contactor is clamped from the third switch 222 by the clamping mechanism 300 to disconnect the third switch 222.

[0056] The present application also provides a method for detecting the insulation state of a power transformer, which is implemented by the power transformer insulation state detection device described in any one of the above technical solutions, and can simplify the operation process of high-voltage oscillation wave detection on the power transformer, reduce the probability of human operation errors, and improve the efficiency of high-voltage oscillation wave detection on the power transformer. Figure 8 As shown, the power transformer insulation state detection method comprises the following steps: Step S100: selecting the required resistance value of the current limiting resistor, the inductance value of the modulating inductor and the capacitance value of the charging capacitor; Step S200: Connect one end of the transformer winding to the signal output port, and the other end to the signal input port; Step S300: enabling the high voltage DC generator to output a required voltage; Step S400: closing the first switch to charge the charging capacitor, and opening the first switch after the charging capacitor is fully charged; Step S500: closing the second switch and collecting the oscillation wave signal; Step S600: extracting a signal characteristic value according to the oscillation wave signal; Step S700: performing fault diagnosis on transformer windings according to the signal characteristic values.

[0057] Wherein, in step S100, the resistance value of the current limiting resistor, the inductance value of the modulating inductor 230 and the capacitance value of the charging capacitor are selected according to the specific type and parameters of the detected power transformer; The resistance value of the current-limiting resistor is adjusted by sliding the resistor slider 640 on the support crossbar 620 to place the resistor contact clip 630 at different positions on the resistor rod 610, thereby causing the current to flow through the resistor rods 610 of different lengths; The height of the inductor winding 232 is adjusted by extending and retracting the multiple telescopic columns 235 to different lengths, thereby adjusting the contact position of the probe 231, wherein the position of the probe 231 is fixed, and the current flows into or out of the inductor winding 232 through the probe 231. When the height position of the inductor winding 232 changes, the position where the probe 231 contacts the inductor winding 232 changes, thereby changing the number of turns of the current flowing through the winding, thereby changing the inductance of the modulated inductor 230; The rotating shaft 431 is driven to rotate by a rotating motor 410 to a set angle to adjust the overlapping area of ​​the projections of the first capacitor plate 422 and the second capacitor plate 432 on the circumferential direction of the rotating shaft 431 , thereby adjusting the capacitance value of the charging capacitor.

[0058] In step S200, the power transformer usually has three phases, and each phase has multiple transformer windings, such as a low-voltage winding, a medium-voltage winding and a high-voltage winding, or a low-voltage winding and a high-voltage winding. After one end of the transformer winding of the power transformer is connected to the signal output port 115, the other end is connected to the signal input port 116, and the other transformer windings are all grounded.

[0059] After checking and confirming that the wiring is correct, check and confirm that the transformer windings and that no one is working nearby before proceeding with subsequent operations. During the operation, you should shout loudly to ensure safety.

[0060] In step S300, the knob switch 540 is operated to make the high-voltage DC generator output a suitable voltage level. During this process, the operator should put his hand near the knob switch 540 to be alert at all times and shut down the high-voltage DC generator in time when an abnormal situation occurs.

[0061] In step S400, the traction motor is rotated to wind the traction winding 215, and the traction winding 215 drives the telescopic head 214 to overcome the resistance of the reset spring and contact the contact head 213. The reset spring is stretched, thereby realizing the closing of the first switch 210. At this time, the high-voltage DC generator will charge the charging capacitor. When the charging capacitor is full, the traction motor rotates in the opposite direction. Under the action of the reset spring, the telescopic head 214 is reset and separated from the contact head 213, so that the first switch 210 is disconnected. During this process, the second switch 221 and the third switch 222 are always at the disconnection terminal.

[0062] In step S500, the contactor is placed at the second switch 221 by using the clamping mechanism 300 to close the second switch 221. At this time, the charging capacitor, the modulation inductor 230 and the transformer winding, which are equivalent to energy storage elements, begin to discharge. This discharge process is also a process of charging these energy storage elements with each other. Therefore, since these energy storage elements are constantly charged and discharged with each other, and energy is lost due to the sampling resistor 119 and the equivalent resistance of the transformer winding, an oscillation wave is generated. The oscillation wave waveform can be observed from the display screen 700. By collecting this oscillation wave signal and connecting to different windings of the power transformer, the oscillation waveform diagrams of different windings can be obtained.

[0063] For example, Fig. 9 The present invention is an oscillation waveform diagram of the high-voltage winding of the power transformer obtained by using the power transformer insulation state detection device of the present invention, wherein O1-A1 refers to an oscillation waveform curve obtained by inputting from the neutral point of the high-voltage winding and outputting from the A phase, O1-B1 refers to an oscillation waveform curve obtained by inputting from the neutral point of the high-voltage winding and outputting from the B phase, and O1-C1 refers to an oscillation waveform curve obtained by inputting from the neutral point of the high-voltage winding and outputting from the C phase.

[0064] Fig.10 The present invention is an oscillation waveform diagram of the medium voltage winding of the power transformer obtained by using the power transformer insulation state detection device of the present invention, wherein O2-A2 refers to an oscillation waveform curve obtained by inputting from the neutral point of the medium voltage winding and outputting from the A phase, O2-B2 refers to an oscillation waveform curve obtained by inputting from the neutral point of the medium voltage winding and outputting from the B phase, and O2-C2 refers to an oscillation waveform curve obtained by inputting from the neutral point of the medium voltage winding and outputting from the C phase.

[0065] Fig.11 The present invention is an oscillation waveform diagram of a low-voltage winding of a power transformer obtained by using the power transformer insulation state detection device of the present invention, wherein A3-B3 refers to an oscillation waveform curve obtained by inputting from the A phase of the low-voltage winding and outputting from the B phase, A3-C3 refers to an oscillation waveform curve obtained by inputting from the A phase of the low-voltage winding and outputting from the C phase, B3-A3 refers to an oscillation waveform curve obtained by inputting from the B phase of the low-voltage winding and outputting from the A phase, B3-C3 refers to an oscillation waveform curve obtained by inputting from the B phase of the low-voltage winding and outputting from the C phase, C3-A3 refers to an oscillation waveform curve obtained by inputting from the C phase of the low-voltage winding and outputting from the A phase, and C3-B3 refers to an oscillation waveform curve obtained by inputting from the C phase of the low-voltage winding and outputting from the B phase.

[0066] It should be noted that after the experiment, the knob switch 540 is operated to turn off the high-voltage DC generator, and then the discharge rod is used to discharge the test winding and ground it. After confirming that the discharge is completed, the contactor is clamped from the second switch 221 by the clamping mechanism 300 to disconnect the second switch 221.

[0067] In step S600, firstly, all the extreme values ​​of the oscillation wave signal are extracted from the oscillation wave signal. for: ; Among them, y is the obtained oscillation wave signal, and U is the voltage amplitude.

[0068] Signal characteristics of the obtained oscillation wave signal for: ; in, is the obtained oscillation wave signal extreme value The difference between the maximum and minimum values ​​of .

[0069] According to the final extracted signal features Perform fault diagnosis on transformer windings.

[0070] Specifically, if the signal characteristic value is greater than or equal to the first set value, the transformer winding is severely deformed and cannot be used; if the signal characteristic value is less than the first set value and greater than or equal to the second set value, the transformer winding is obviously deformed and cannot be used; if the signal characteristic value is less than the second set value and greater than 0, the transformer winding is slightly deformed or not deformed and can be used normally. The first set value ranges from 0.08 to 0.2, and the second set value ranges from 0.02 to 0.05.

[0071] In one embodiment, the first setting value is 0.1, and the second setting value is 0.03, that is, when When the transformer winding is severely deformed, it cannot be used; when When the transformer winding is obviously deformed, it cannot be used; when When the transformer winding is slightly deformed or not deformed, the transformer winding can be used normally. In other embodiments, the first set value and the second set value can also be other values.

[0072] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A device for detecting insulation status of a power transformer, characterized in that: It comprises a frame and a high-voltage direct current generator, an ammeter, a current limiting resistor, a first switch, a sampling resistor, a charging capacitor, a wave modulation inductor, a signal output port and a signal input port which are arranged on the frame and connected in series in sequence; the voltage of the high-voltage direct current generator, the size of the current limiting resistor, the size of the wave modulation inductor and the size of the charging capacitor are adjustable; The signal output port and the signal input port are used to connect to the transformer winding; It also includes an interlock switch, the interlock switch includes a second switch and a third switch, one end of the second switch is connected to the zero voltage point, and the other end is connected between the first switch and the sampling resistor; The third switch is connected in parallel with the current limiting resistor, the first switch, the sampling resistor, the charging capacitor and the modulating inductor.

2. The power transformer insulation state detection device according to claim 1, characterized in that: The modulated inductor includes a probe, an inductor winding and a winding height adjustment component. One end of the probe is fixed on the frame, and the other end abuts the inductor winding. The winding height adjustment component is used to adjust the height of the inductor winding and thus adjust the abutment position of the probe.

3. The power transformer insulation state detection device according to claim 2, characterized in that: The winding height adjustment assembly includes an upper chassis, a lower chassis and a plurality of telescopic columns, wherein the lower chassis is fixed on the frame, the upper chassis is fixed at the bottom of the inductor winding, one end of the plurality of telescopic columns is connected to the lower chassis, and the other end is connected to the upper chassis.

4. The power transformer insulation state detection device according to claim 1, characterized in that: The second switch includes a first housing and a contactor assembly disposed on the first housing, the third switch includes a second housing and a contactor assembly disposed on the second housing, the first housing and the second housing are arranged in parallel and spaced apart, and the interlock switch further includes a contact ball, the contact ball is used to be placed on the first housing or the second housing and contact the contactor assembly to close the second switch or the third switch.

5. The power transformer insulation state detection device according to claim 4, characterized in that: The interlock switch further includes a clamping mechanism, which is disposed on the frame and is used to clamp the contact ball and place the contactor on the first housing or the second housing.

6. The power transformer insulation state detection device according to claim 5, characterized in that: The clamping mechanism includes a front-to-back moving component, a left-to-right moving component, an up-and-down moving component and a clamping arm, the front-to-back moving component is arranged on the frame, the left-to-right moving component is arranged on the front-to-back moving component, the up-and-down moving component is arranged on the left-to-right moving component, and the clamping arm is arranged on the up-and-down moving component.

7. The power transformer insulation state detection device according to claim 1, characterized in that: The charging capacitor includes a first capacitor component, a second capacitor component and a rotating motor, the first capacitor component includes a fixed shaft and a plurality of first capacitor plates arranged on the fixed shaft, the fixed shaft is fixed to the frame, the second capacitor component includes a rotating shaft and a plurality of second capacitor plates arranged on the rotating shaft, the plurality of first capacitor plates and the plurality of second capacitor plates are arranged alternately and spaced one by one, the rotating shaft is rotatably arranged on the frame, and the rotating motor is used to drive the rotating shaft to rotate a set angle to adjust the overlapping area of ​​the projections of the first capacitor plates and the second capacitor plates on the circumferential direction of the rotating shaft.

8. The power transformer insulation state detection device according to claim 1, characterized in that: It also includes a display screen fixed on the frame, and the display screen is used to display the reading of the ammeter.

9. A method for detecting the insulation status of a power transformer, characterized in that: The method is implemented by the power transformer insulation state detection device according to any one of claims 1 to 8, comprising: Step S100: selecting the required resistance value of the current limiting resistor, the inductance value of the modulating inductor and the capacitance value of the charging capacitor; Step S200: Connect one end of the transformer winding to the signal output port, and the other end to the signal input port; Step S300: enabling the high voltage DC generator to output a required voltage; Step S400: closing the first switch to charge the charging capacitor, and opening the first switch after the charging capacitor is fully charged; Step S500: closing the second switch and collecting the oscillation wave signal; Step S600: extracting a signal characteristic value according to the oscillation wave signal; Step S700: performing fault diagnosis on transformer windings according to the signal characteristic values.

10. The method for detecting insulation status of a power transformer according to claim 9, characterized in that: If the signal characteristic value is greater than or equal to the first set value, the transformer winding is severely deformed and cannot be used; if the signal characteristic value is less than the first set value and greater than or equal to the second set value, the transformer winding is obviously deformed and cannot be used; if the signal characteristic value is less than the second set value and greater than 0, the transformer winding is slightly deformed or not deformed and can be used normally.

Images