Intelligent box low voltage ride through test platform

Abstract

The application relates to the technical field of box transformer through test, in particular to a low-voltage through test platform of an intelligent box transformer, which comprises a box transformer, a test main body and a mechanical drive; the test main body comprises a box body fixed on the low-voltage outgoing line side of the box transformer and a sliding resistor arranged in the box body, the low-voltage outgoing line of the box transformer is connected to the sliding resistor and forms a closed loop connection with a low-voltage protector in the box transformer, the mechanical drive comprises a motor fixed in the box body and a lead screw installed on the output shaft of the motor, and sliding contacts of the sliding resistor are driven on the lead screw; the mechanical drive further comprises a disengaging mechanism, a starting motor completes one-time driving, and through the above mechanical transmission principle, one-time low-voltage setting is completed through the mode of adjusting the resistor, so that one-time low-voltage through detection is completed. Therefore, the service life of the detection function is improved, and the additional loss is small.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of box transformer crossing test, in particular to a low voltage crossing test platform of intelligent box transformer. BACKGROUND

[0002] The low voltage crossing capability detection of box transformer refers to the comprehensive and automatic verification of the low voltage crossing capability of intelligent box transformer (especially the internal intelligent protection measurement and control device, communication system and overall collaborative control logic), verifying whether the box transformer can send the specified reactive current according to the standard (such as Q / U curve) and support the voltage recovery capability of the power grid, verifying whether the box transformer can smoothly recover normal operation after fault clearing, without overcurrent and oscillation. It generally has a graphical interface to facilitate users to intuitively obtain phase parameters. As a key node of distribution network, the grid-connected operation stability of box transformer is crucial. When the voltage drops due to short circuit fault and other faults of power grid, the box transformer is required to have low voltage crossing capability.

[0003] At present, the mainstream equipment for low voltage crossing test of box transformer mostly uses voltage drop simulator based on full-controlled power electronic devices (such as IGBT). This kind of equipment needs complex circuit support, contains a large number of electronic components in the system, and has high operation and maintenance cost; after low voltage crossing detection, it cannot quickly recover to normal state, resulting in that the simulator is continuously connected in the wire, which will generate large additional loss and affect the service life of the simulator. SUMMARY

[0004] In order to solve the above problems, the present application provides a low voltage crossing test platform of intelligent box transformer, which comprises a box transformer, a test main body and a mechanical drive.

[0005] The test main body comprises a box body fixed on the low voltage outgoing line side of the box transformer and a sliding resistor arranged in the box body, and the low voltage outgoing line of the box transformer is connected to the sliding resistor and forms a closed loop connection with the low voltage protector in the box transformer. The mechanical drive comprises a motor fixed in the box body and a lead screw installed on the output shaft of the motor, and the sliding contact of the sliding resistor is driven on the lead screw.

[0006] The mechanical drive further comprises a disengaging mechanism, the disengaging mechanism comprises a passive disengaging body arranged on the sliding contact and an active disengaging body arranged in the box body, the active disengaging body is on the same side as the input side of the sliding resistor, and the active disengaging body and the passive disengaging body form a touching relationship. When the passive disengaging body retreats to the touching relationship with the active disengaging body, the sliding contact is separated from the resistance wire of the sliding resistor.

[0007] As a further preferred, still comprising a core control unit, the core control unit is provided with a servo driver, the servo driver is electrically connected with the motor, and is used to send control instructions to the motor based on a preset low voltage ride through threshold, and makes the core control unit convert a standard voltage, time drop curve into a position executed by the motor, and controls the voltage drop time and voltage recovery through the rotation angle and speed of the motor.

[0008] As a further preferred, still comprising a signal acquisition unit, the signal acquisition unit comprises a voltage transformer and a current transformer, and is connected with the low voltage output side of the box transformer, and is used to acquire voltage and current signals.

[0009] As a further preferred, still comprising a man-machine interaction unit, which is communicatively connected with the core control unit, and is used to display data, test state and warning information of the signal acquisition unit, and receive operation instructions.

[0010] As a further preferred, the sliding contact comprises a sliding seat driven by the lead screw and a contact plate arranged on both sides of the sliding seat and sliding on the resistance wire, the two contact plates are pivotally connected with the sliding seat, the passive disengaging body is a slanted trigger plate arranged on the trailing end of the two contact plates, the active disengaging body is a horizontal trigger plate arranged in the box and located on the trailing side of the passive disengaging body, and the passive disengaging body is fixed with a protruding contact part corresponding to the slanted surface of the passive disengaging body.

[0011] As a further preferred, the contact plate is an outwardly curved arc-shaped spring sheet, wherein the protruding surface of the arc-shaped spring sheet contacts the resistance wire.

[0012] As a further preferred, the box is fixed with an assembly plate, the test body and the mechanical drive are suspendedly installed in the box through the assembly plate, the bottom of the box is provided with a tapered cavity in an upper-lower suspension relationship with the test body and the mechanical drive, the bottom of the tapered cavity is connected with a downwardly extending air outlet pipe,

[0013] As a further preferred, the top of the box is provided with an air inlet, the air inlet vertically corresponds to the output side of the sliding resistance, the motor is located at the back of the input side of the sliding resistance, and a distance gap is formed between the motor and the sliding resistance.

[0014] The beneficial effects of the present application compared with the prior art are:

[0015] 1. A sliding resistor is arranged on the low-voltage output side of the box transformer to be tested as a load simulating the voltage drop of the power grid, and the output end of the sliding resistor is connected to the low-voltage tripping device inside the box transformer, so that the contact plate on the sliding resistor moves from the maximum resistance position to the minimum resistance position in the closed loop circuit. During this process, according to Ohm's law, the total impedance in the closed loop circuit decreases, and the current increases. This large current will cause a large voltage drop on the winding and line impedance inside the box transformer, thereby significantly reducing the voltage U at the output end of the box transformer, thereby simulating the voltage drop on the power grid side and detecting whether the protection device inside the box transformer acts. If the box transformer can follow the set low-voltage ride-through curve, it proves that the low-voltage ride-through test of the box transformer is passed. Otherwise, if the box transformer fails to follow the set low-voltage ride-through curve, it proves that the low-voltage ride-through test of the box transformer is not passed. The cost and manufacturing threshold of the test platform are greatly reduced, the structure is solid, the maintenance is simple, mature industrial motor and control technology are adopted, the fragility and harmonic problem of power electronic devices are avoided, and the test process is clean and reliable.

[0016] 2. A disengagement mechanism is arranged at one end of the sliding resistor in the box body. After detection, the sliding contact is reset to touch the passive disengagement body of the disengagement mechanism and the active disengagement body of the disengagement mechanism, deform the passive disengagement body, and separate the contact surface of the passive disengagement body from the resistance wire on the sliding resistor under the action of deformation. At this time, the current passes through the resistance wire of the sliding resistor. Since the current avoids the resistance wire at this time, the closed loop circuit switches from detection to normal state. A timing module is arranged in the control system, for example, an instruction is issued to the servo driver every two hours to start the motor to complete a drive, and a low-voltage setting is completed by adjusting the resistance through the above mechanical transmission principle, thereby completing a low-voltage ride-through detection. As can be seen, the service life of the detection function is improved, and the additional loss is small. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 A schematic view of the front side of a low-voltage ride-through test platform of an intelligent box transformer provided by an embodiment of the present application;

[0018] Figure 2 A low-voltage ride-through test platform of an intelligent box transformer provided by an embodiment of the present application is Figure 1 An enlarged schematic view of part A;

[0019] Figure 3 A low-voltage ride-through test platform of an intelligent box transformer provided by an embodiment of the present application is Figure 1 A schematic view of the bottom from the top view of a low-voltage ride-through test platform of an intelligent box transformer provided by an embodiment of the present application;

[0020] Figure 4 A low-voltage ride-through test platform of an intelligent box transformer provided by an embodiment of the present application is Figure 1The schematic diagram under the right side view angle of the lead-out;

[0021] Figure 5 The local structure schematic diagram after longitudinal section of the box in the low voltage ride through test platform of the intelligent box transformer provided by the embodiment of the present application;

[0022] Figure 6 The schematic diagram under the box transformer view angle of the low voltage ride through test platform of the intelligent box transformer provided by the embodiment of the present application, the transformer in the box transformer is also the low voltage output side input to the test main body direction;

[0023] Figure 7 The working principle block diagram of the low voltage ride through test platform of the intelligent box transformer provided by the embodiment of the present application.

[0024] In the figure: 1, the box transformer; 2, the test main body; 21, the box; 211, the closed cavity; 212, the air outlet pipe; 213, the assembly plate; 214, the air inlet; 22, the sliding resistance; 221, the sliding contact; 2211, the sliding seat; 2212, the contact plate; 3, the mechanical drive; 31, the motor; 32, the screw rod; 33, the disengaging mechanism; 331, the passive disengaging body; 3311, the convex contact part; 332, the active disengaging body. DETAILED DESCRIPTION

[0025] The above and other embodiments and advantages of the present application are more fully described below in conjunction with the attached drawings. It is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments of the present application.

[0026] In an embodiment, as shown in Figures 1-7

[0027] ​The embodiment provides a low-voltage ride-through test platform of an intelligent box transformer, which comprises a box transformer 1, a test main body 2 and a mechanical drive 3; the test main body 2 comprises a box body 21 fixed at a low-voltage outgoing line side of the box transformer 1 and a sliding resistance 22 arranged in the box body 21, and the low-voltage outgoing line of the box transformer 1 is connected to the sliding resistance 22 and forms a closed loop connection with a low-voltage protector in the box transformer 1; the mechanical drive 3 comprises a motor 31 fixed in the box body 21 and a lead screw 32 installed on an output shaft of the motor 31, and a sliding contact 221 of the sliding resistance 22 is driven on the lead screw 32; the mechanical drive 3 further comprises a disengaging mechanism 33, which comprises a passive disengaging body 331 arranged on the sliding contact 221 and an active disengaging body 332 arranged in the box body 21, the active disengaging body 332 is on the same side as an input side of the sliding resistance 22 and forms a touching relationship with the passive disengaging body 331, and when the passive disengaging body 331 retreats to the touching relationship with the active disengaging body 332, the sliding contact 221 is separated from a resistance wire of the sliding resistance 22. The input end of the sliding resistance 22 is connected to the low-voltage output side of the box transformer 1 through an electric wire, and the output end of the sliding resistance 22 enters the box transformer 1 and is connected to a low-voltage release, and the low-voltage ride-through is detected in the closed loop circuit through the test main body 2 and the mechanical drive 3 provided by the embodiment as follows: a core control unit reads preset test parameters (such as jumping to 20% rated voltage, lasting 625 ms), then sends an instruction to a servo driver, the motor 31 is controlled by the servo driver and the lead screw 32 is rotated by the motor 31, the sliding contact 221 is moved along the resistance wire under the rotation of the lead screw 32, and the sliding contact 221 is moved from a maximum resistance position (input side) to a minimum resistance position (output side) of the sliding resistance 22. In this process, according to the Ohm's law, the total impedance on the closed loop circuit is reduced, and the current is increased. At this time, the large current will produce a huge voltage drop on the winding and line impedance in the box transformer 1, thereby causing the voltage U of the output end of the box transformer 1 to be significantly reduced, thereby simulating the voltage drop of the grid side (low-voltage side), and whether the protection device (low-voltage release) in the box transformer 1 under test acts or not. If the box transformer 1 can follow the set low-voltage ride-through curve (such as the voltage drops to 20% rated voltage, lasting 625 ms without tripping, i.e. the preset test threshold), it is proved that the low-voltage ride-through test of the box transformer 1 is passed; otherwise, if the box transformer 1 fails to follow the set low-voltage ride-through curve (such as the voltage drops to 20% rated voltage, lasting 625 ms with tripping), it is proved that the low-voltage ride-through test of the box transformer 1 is not passed.

[0028] In addition, after the sliding contact 221 completes the above detection and advances to the point where the passive disengaging body 331 and the active disengaging body 332 come into contact, the passive disengaging body 331 is deformed by the active disengaging body 332, and the contact surface of the passive disengaging body 331 is separated from the resistance wire on the sliding resistor 22 under the action of deformation. At this time, the current passing through the sliding resistor 22 avoids the resistance wire, enters the output side of the sliding resistor 22 from the upper passage, and finally enters the transformer substation 1 to complete the closed loop. Since the current avoids the resistance wire at this time, the closed loop circuit is switched from detection to normal state. A timing module is provided in the control system, for example, an instruction is issued to the servo driver every two hours to start the motor 31 to complete a drive, and through the above mechanical transmission principle, a low voltage setting is completed by adjusting the resistance to complete a low voltage ride through detection. Therefore, the service life of the detection function is improved, and the additional loss is small.

[0029] The abstract voltage curve control problem is converted into a specific mechanical position control problem, which greatly reduces the cost and manufacturing threshold of the test platform. The structure is solid and easy to maintain. Mature industrial motors and control technologies are used to avoid the fragility and harmonic problems of power electronic devices. The test process is clean and reliable, and the maintenance probability is reduced.

[0030] In another embodiment, as shown in Figure 7 The detection platform further includes a core control unit (single-chip microcomputer), and at least a servo driver or drive module in the core control unit is electrically connected to the motor 31 and sends control instructions to the motor 31 based on a preset low voltage ride through threshold, and the core control unit converts a standard voltage, time drop curve into a position executed by the motor 31, and realizes accurate control of voltage drop time and voltage recovery through the rotation angle and speed of the motor 31. The servo motor controlled by the program can accurately reproduce the standard required voltage drop curve, ensuring the repeatability and accuracy of the test results.

[0031] In another embodiment, as shown in Figure 7 The detection platform further includes a signal acquisition unit, and the signal acquisition unit includes a voltage transformer and a current transformer connected to the low voltage output side of the transformer substation 1 for collecting voltage and current signals. The signal acquisition unit monitors the electrical parameters of the transformer substation output side in real time through the voltage / current transformer, and sends the isolated and converted signals to the core control unit for processing.

[0032] In another embodiment, as shown in Figure 7As shown, the testing platform also includes a human-machine interface unit, which comprises a local touchscreen and / or a remote monitoring computer. This unit communicates with the core control unit to display data from the signal acquisition unit, test status, and warning messages, and to receive operation commands. The voltage and current waveforms throughout the process are recorded in real time and displayed on the touchscreen. If the low-voltage protection device inside the transformer trips during a voltage drop, the signal acquisition unit will detect this change, and the core control unit will immediately mark "test failed" in the event log and trigger an audible and visual alarm to notify on-site personnel.

[0033] In another implementation, such as Figures 2 to 5 As shown, the sliding contact 221 includes a slide 2211 driven by the lead screw 32 and contact plates 2212 disposed on both sides of the slide 2211 and sliding on the resistance wire. The two contact plates 2212 are connected to the slide 2211 by a rotating shaft. The passive release body 331 refers to the inclined trigger plate disposed on the two contact plates 2212. The active release body 332 refers to the horizontal trigger plate disposed inside the housing 21 and located on the reverse retraction side of the passive release body 331. The passive release body 331 has a protruding contact portion 3311 fixed on it, which corresponds to the inclined surface of the passive release body 331. When the sliding contact 221 returns to its original position according to the preset command of the core control unit (after the voltage drops to 20% of the rated voltage for 625ms), the passive release body 331 will bring the protruding contact 3311 into contact with the active release body 332. The active release body 332 provides a reaction force to the protruding contact 3311, forcing the protruding contact 3311 to push the two passive release bodies 331 to drive the two contact plates 2212 to detach from the resistance wire in opposite directions. By using mechanical contact, the current passing through the sliding resistor 22 can bypass the resistance wire, and the structure is simple.

[0034] In another implementation, such as Figure 2 As shown, the contact plate 2212 is an outwardly curved arc-shaped spring sheet, with its arc-shaped convex surface contacting the resistance wire. The contact plate 2212 is elastic, and after losing the constraint of the active release body 332, it quickly and elastically contacts the resistance wire, providing circuit connection conditions for the next resistive analog low-voltage detection.

[0035] In another implementation, such as Figures 1 to 3As shown, the box 21 is fixed with the assembly plate 213, the test body 2 and the mechanical drive 3 are installed in the box 21 in a suspended manner through the assembly plate 213, the bottom of the box 21 is provided with the closed cavity 211 which forms an up-down suspended relationship with the test body 2 and the mechanical drive 3, and the bottom of the closed cavity 211 is connected with the downward extending air outlet pipe 212. When the mechanical drive 3 and the test body 2 change the large current (simulate low voltage), the generated heat is much higher than normal, the closed cavity 211 is a heat dissipation cavity, which discharges these heat downward through the air outlet pipe 212 to avoid fire. In addition, the top of the box 21 is provided with the air inlet 214 which vertically corresponds to the output side of the sliding resistance 22, the motor 31 is located at the back of the input side of the sliding resistance 22 and forms a distance gap with the sliding resistance 22, the distance gap is a heat dissipation space which can release heat to the closed cavity 211, and in actual use, a fan can be installed on the top of the box 21, the air outlet of the fan is connected to the air inlet 214 to improve the heat dissipation efficiency, and the core control unit also controls the fan to be powered on each time when the detection is performed, and the heat released by the resistance wire on the sliding resistance 22 is assisted during the simulation detection.

[0036] The above orientation reference does not represent the specific orientation of each component in the embodiment, and the embodiment is only for the convenience of the description of the scheme and is described relatively by referring to the orientation in the figure. In fact, the specific orientation of each component is described according to the actual installation and actual use and the orientation description habit of the person skilled in the art, and this is stated.

[0037] The above specific embodiments further specifically describe the purposes, technical schemes and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and does not limit the protection scope of the present application. It is particularly pointed out that any modification, equivalent replacement, improvement, etc. made by the person skilled in the art within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A low-voltage ride-through test platform for intelligent prefabricated substations, characterized in that, It comprises a box transformer (1), a test main body (2) and a mechanical drive (3); The test main body (2) comprises a box (21) fixed on the low-voltage outgoing line side of the box transformer (1) and a sliding resistance (22) arranged in the box (21), and the low-voltage outgoing line of the box transformer (1) is connected to the sliding resistance (22) and forms a closed loop connection with the low-voltage protector in the box transformer (1); The mechanical drive (3) comprises a motor (31) fixed in the box (21) and a lead screw (32) installed on the output shaft of the motor (31), and the sliding contact (221) of the sliding resistance (22) is driven on the lead screw (32), and the mechanical drive (3) further comprises a disengaging mechanism (33), the disengaging mechanism (33) comprises a passive disengaging body (331) arranged on the sliding contact (221), and an active disengaging body (332) arranged in the box (21), the active disengaging body (332) is on the same side as the input side of the sliding resistance (22), and forms a touching relationship with the passive disengaging body (331), when the passive disengaging body (331) retreats to the touching relationship with the active disengaging body (332), the sliding contact (221) is separated from the resistance wire of the sliding resistance (22); The sliding contact (221) comprises a sliding seat (2211) driven on the lead screw (32) and a contact plate (2212) arranged on both sides of the sliding seat (2211) and sliding on the resistance wire, the two contact plates (2212) are pivotally connected with the sliding seat (2211), the passive disengaging body (331) is an inclined trigger plate arranged on the rear end of the two contact plates (2212), the active disengaging body (332) is a horizontal trigger plate arranged in the box (21) and located on the retreat side of the passive disengaging body (331), and the passive disengaging body (331) is fixed with a convex contact part (3311) corresponding to the inclined surface of the passive disengaging body (331).

2. The low voltage ride through test platform of claim 1, wherein, It further comprises a core control unit, a servo driver is arranged in the core control unit, the servo driver is electrically connected with the motor (31), and is used to send a control instruction to the motor (31) based on a preset low-voltage ride-through threshold, and the core control unit is used to convert a standard voltage, time drop curve into a position executed by the motor (31), and the rotation angle and speed of the motor (31) are used to realize control of voltage drop time and voltage recovery.

3. The low voltage ride through test platform for a smart box transformer of claim 2, wherein, It further comprises a signal acquisition unit, the signal acquisition unit comprises a voltage transformer and a current transformer, and is connected with the low-voltage output side of the box transformer (1) and used to acquire voltage and current signals.

4. The low voltage ride through test platform of claim 3, wherein, It further comprises a man-machine interaction unit, which is in communication connection with the core control unit and is used to display data, test state and warning information of the signal acquisition unit and receive operation instructions.

5. The low voltage ride through test platform for a smart box transformer of claim 1, wherein, The contact plate (2212) is an outwardly curved arc-shaped spring sheet, wherein the convex surface of the arc-shaped spring sheet contacts the resistance wire.

6. The low voltage ride through test platform for a smart box transformer of claim 5, wherein, The box (21) is fixed with an assembly plate (213), the test main body (2) and the mechanical drive (3) are installed in the box (21) in a suspended manner through the assembly plate (213), the bottom of the box (21) is provided with a closed cavity (211) which forms an up-down suspended relationship with the test main body (2) and the mechanical drive (3), and the bottom of the closed cavity (211) is connected with a downward extending air outlet pipe (212).

7. The low voltage ride through test platform of claim 6, wherein, The top of the box (21) is provided with an air inlet (214), the air inlet (214) vertically corresponds to the output side of the sliding resistance (22), the motor (31) is located at the back of the input side of the sliding resistance (22) and forms a distance gap with the sliding resistance (22).

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