CN111030049A - Transformer neutral point protection method and device - Google Patents
Transformer neutral point protection method and device Download PDFInfo
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- CN111030049A CN111030049A CN201911132555.0A CN201911132555A CN111030049A CN 111030049 A CN111030049 A CN 111030049A CN 201911132555 A CN201911132555 A CN 201911132555A CN 111030049 A CN111030049 A CN 111030049A
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- 230000007935 neutral effect Effects 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 20
- 239000004020 conductor Substances 0.000 claims abstract description 28
- 230000005540 biological transmission Effects 0.000 claims description 40
- 238000004146 energy storage Methods 0.000 claims description 21
- 230000001276 controlling effect Effects 0.000 description 9
- 238000009413 insulation Methods 0.000 description 5
- 230000009471 action Effects 0.000 description 4
- 239000000725 suspension Substances 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 230000007257 malfunction Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/04—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for transformers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H3/00—Mechanisms for operating contacts
- H01H3/32—Driving mechanisms, i.e. for transmitting driving force to the contacts
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H3/00—Mechanisms for operating contacts
- H01H3/32—Driving mechanisms, i.e. for transmitting driving force to the contacts
- H01H3/38—Driving mechanisms, i.e. for transmitting driving force to the contacts using spring or other flexible shaft coupling
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Abstract
The application provides a method and a device for protecting a neutral point of a transformer, wherein three-phase voltage of a bus is obtained to obtain a voltage effective value, and whether a controllable grounding switch assembly is controlled to be closed or not is determined based on the voltage effective value and a preset voltage threshold value; and if the controllable grounding switch component is closed, acquiring the current of the secondary side of the current transformer electrically connected with the conductor to obtain a current effective value. Determining whether to control the time relay to work or not based on the current effective value and a preset current threshold value; and if the time relay works, acquiring the current working time of the time relay, and determining whether to control the controllable grounding switch assembly to be disconnected or not based on the current working time and a preset time threshold. This application adopts above-mentioned control mode, can controllable earthing switch subassembly closed back, reliable and effectual will controllable earthing switch subassembly disconnection to avoid the potential safety hazard that the maloperation arouses, improve the security.
Description
Technical Field
The application relates to the technical field of transformers, in particular to a transformer neutral point protection method and device.
Background
Electrical industry standard DL/T620-1997 overvoltage protection and insulation coordination for ac electrical devices, 4.1.1b specifies: the accidental formation of a local ungrounded system in an effective grounding system of 110kV and 220kV is avoided, and high power frequency overvoltage is generated. Gaps should be provided for non-grounded neutral points of 110kV and 220kV transformers with power on the low voltage side that may form such local systems. The gap should act when a local ungrounded system is formed due to a ground fault; the system operates in an effective grounding mode and the clearance should not act when a single-phase grounding fault occurs.
At present, a transformer neutral point protection device is of an open structure, and a discharge gap is a rod-rod gap which takes air as an insulating medium. The working principle of the traditional rod-rod gap is that the gap distance can bear specified power frequency voltage after being adjusted according to the technical requirements; when the power frequency overvoltage of the system exceeds the bearing range of the gap, the gap breaks down. However, the conventional discharge gap is greatly affected by the environment, and in actual operation, because the protection gap cannot automatically extinguish the arc, the arc needs to be cut off by relay protection, so that relay protection misoperation can be caused, and the reliability is poor.
Disclosure of Invention
Therefore, it is necessary to provide a method and an apparatus for protecting a neutral point of a transformer, which are used to solve the problems that the discharge gap of the neutral point of the existing transformer is greatly affected by the environment, and the arc is required to be cut off by relay protection because the protection gap cannot be self-extinguished in the actual operation, thereby causing the problem of malfunction of the relay protection and having poor reliability.
A transformer neutral point protection method is applied to a transformer neutral point protection device, and comprises the following steps:
acquiring three-phase voltage of a bus to obtain a voltage effective value;
determining whether to control the controllable grounding switch assembly to be closed or not based on the voltage effective value and a preset voltage threshold value;
if the controllable grounding switch component is closed, acquiring the current of the secondary side of the current transformer electrically connected with the conductor to obtain a current effective value;
determining whether to control the time relay to work or not based on the current effective value and a preset current threshold value;
and if the time relay works, acquiring the current working time of the time relay, and determining whether to control the controllable grounding switch assembly to be disconnected or not based on the current working time and a preset time threshold.
In one embodiment, the step of obtaining the three-phase voltage of the bus to obtain the effective voltage value includes:
and acquiring the three-phase voltage of the bus through a voltage transformer, and obtaining the effective voltage value.
In one embodiment, the step of determining whether to control the controllable grounding switch assembly to be closed based on the voltage effective value and a preset voltage threshold value comprises:
acquiring the preset voltage threshold, and comparing the preset voltage threshold with the voltage effective value to obtain a voltage comparison result;
if the voltage comparison result shows that the voltage effective value is greater than or equal to the preset voltage threshold, controlling the controllable grounding switch component to be closed;
and if the voltage comparison result shows that the effective voltage value is smaller than the preset voltage threshold, the controllable grounding switch component is not controlled to be closed.
In one embodiment, the step of determining whether to control the operation of the time relay based on the effective current value and the preset current threshold value includes:
acquiring the preset current threshold, and comparing the preset current threshold with the current effective value to obtain a current comparison result;
if the current comparison result shows that the current effective value is greater than or equal to the preset current threshold, controlling the time relay to work;
and if the current comparison result shows that the effective current value is smaller than the preset current threshold, controlling the time relay to be out of work.
In one embodiment, if the time relay is operated, the step of obtaining the current operating time of the time relay, and determining whether to control the controllable grounding switch assembly to be turned off based on the current operating time and a preset time threshold includes:
if the time relay works, the current working time of the time relay is obtained;
comparing the current working time with the preset time threshold to obtain a time comparison result;
if the time comparison result shows that the current working time is greater than or equal to the preset time threshold, controlling the controllable grounding switch assembly to be switched off;
and if the time comparison result shows that the current working time is less than the preset time threshold, the controllable grounding switch assembly is not controlled to be switched off.
A transformer neutral point protection device comprising:
a conductor;
a controllable ground switch assembly electrically connected to the conductor;
a current transformer electrically connected to the conductor;
a controller electrically connected to the controllable earthing switch assembly and the current transformer, respectively, for performing the transformer neutral point protection method steps according to any one of the above embodiments; and
and the time relay is electrically connected with the controller.
In one embodiment, the transformer neutral point protection device further includes:
and the controller controls the on and off of the controllable grounding switch assembly through the transmission device.
In one embodiment, the transmission comprises:
the driving assembly is arranged on the fixed frame, the first transmission assembly is connected with the driving assembly, the output shaft is connected with the first transmission assembly, and the second transmission assembly and the controllable grounding switch assembly are respectively connected with the output shaft;
the second transmission assembly comprises an energy storage spring, a first crank arm connected with the output shaft, and a spring hanging unit hinged to the first crank arm and used for mounting the energy storage spring.
In one embodiment, the suspension spring unit includes: the energy storage device comprises a first hanging spring plate hinged with the first crank arm and a second hanging spring plate arranged at an interval with the first hanging spring plate, and the energy storage spring is installed between the first hanging spring plate and the second hanging spring plate.
In one embodiment, the controllable ground switch assembly comprises:
the static contact is electrically connected with the conductor;
the moving contact is connected with the transmission device, and the controller controls the moving contact to be in contact with or separated from the fixed contact through the transmission device.
In one embodiment, the transformer neutral point protection device further includes:
and the conductor and the controllable grounding switch assembly are arranged in the closed shell.
Compared with the prior art, the method and the device for protecting the neutral point of the transformer firstly obtain the three-phase voltage of the bus to obtain the voltage effective value, and determine whether to control the controllable grounding switch assembly to be closed or not based on the voltage effective value and the preset voltage threshold value; and if the controllable grounding switch component is closed, acquiring the current of the secondary side of the current transformer electrically connected with the conductor to obtain a current effective value. Determining whether to control the time relay to work or not based on the current effective value and a preset current threshold value; and if the time relay works, acquiring the current working time of the time relay, and determining whether to control the controllable grounding switch assembly to be disconnected or not based on the current working time and a preset time threshold. This application adopts above-mentioned control mode, can controllable earthing switch subassembly closed back, reliable and effectual will controllable earthing switch subassembly disconnection to avoid the potential safety hazard that the maloperation arouses, improve the security.
Drawings
Fig. 1 is a flowchart of a transformer neutral point protection method according to an embodiment of the present application;
fig. 2 is a schematic block diagram of a transformer neutral point protection device according to an embodiment of the present application;
fig. 3 is a schematic structural diagram of a transformer neutral point protection device according to an embodiment of the present application;
FIG. 4 is a front view of a transformer drive according to an embodiment of the present application;
FIG. 5 is a partial top view one of FIG. 4;
fig. 6 is a partial top view two of fig. 4.
10 transformer neutral point protection device
100 conductor
101 ground terminal
102 terminal
200 controllable grounding switch assembly
210 static contact
220 moving contact
230 switch crank arm
240 auxiliary connecting rod
300 current transformer
400 controller
500 time relay
600 driving device
610 fixed mount
611 fixed plate
620 active component
621 driving element
622 output crank arm
630 first transmission assembly
631 first link
632 second crank arm
633 joint
640 output shaft
641 bearing seat
650 second transmission assembly
651 energy storage spring
652 first crank arm
653 hanging spring unit
654 first hanging spring plate
655 second hanging spring plate
660 regulating unit
661 screw rod
662 nut
700 closed casing
701 observation window
Detailed Description
In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and it is therefore not intended to be limited to the embodiments disclosed below.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1, an embodiment of the present application provides a transformer neutral point protection method, which is applied to a transformer neutral point protection apparatus 10. The method comprises the following steps:
s102: and obtaining the three-phase voltage of the bus to obtain the effective voltage value.
In one embodiment, the bus three-phase voltage can be obtained by a controller or an MCU (micro control unit), and the effective value of the voltage can be obtained. Specifically, the bus three-phase voltage can be acquired through a voltage transformer to obtain the voltage effective value, and the controller or the MCU acquires the voltage effective value measured by the voltage transformer.
S104: and determining whether to control the controllable grounding switch assembly to be closed or not based on the voltage effective value and a preset voltage threshold value.
In one embodiment, whether to control the controllable grounding switch component to be closed or not can be determined by the controller or the MCU based on the voltage effective value and a preset voltage threshold value. Specifically, after the controller or the MCU obtains the voltage effective value, the voltage effective value is compared with the preset voltage threshold set in advance to obtain a voltage difference comparison result.
And if the voltage difference comparison result shows that the voltage effective value is greater than or equal to the preset voltage threshold value, determining that the system generates single-phase grounding and earth loss or non-full-phase operation power frequency overvoltage threatening the insulation of the neutral point of the transformer, and controlling the controllable grounding switch component to be closed by the controller or the MCU. After the controllable grounding switch assembly is closed, the single-phase grounding threatening the insulation of the neutral point of the transformer and the loss of the ground or the non-full-phase operation power frequency overvoltage can be directly guided to the ground, so that the damage of the neutral point of the transformer is avoided. If the voltage difference comparison result shows that the effective voltage value is smaller than the preset voltage threshold, the system does not break down at the moment, and the controller or the MCU does not control the controllable grounding switch assembly at the moment.
S106: and if the controllable grounding switch component is closed, acquiring the current of the secondary side of the current transformer electrically connected with the conductor to obtain a current effective value.
In one embodiment, after the controller or the MCU controls the controllable grounding switch assembly to be closed, the secondary side current of the current transformer electrically connected to the conductor can be further obtained to obtain the effective value of the current. Specifically, the controller or the MCU is electrically connected to the current transformer. After the current transformer obtains the current flowing through the conductor, the controller or the MCU can directly obtain the current of the secondary side of the current transformer and obtain the effective value of the current.
S108: and determining whether to control the time relay to work or not based on the current effective value and a preset current threshold value.
In one embodiment, whether to control the time relay to work can be determined by the controller or the MCU based on the effective current value and a preset current threshold. Specifically, after the controller or the MCU obtains the current effective value, the current effective value may be compared with a preset current threshold set in advance to obtain a current difference comparison result.
In an embodiment, if the current difference comparison result is that the current effective value is greater than or equal to the preset current threshold, the controller or the MCU controls the time relay to operate, and records the current operating time of the time relay. And if the current difference value comparison result shows that the current effective value is smaller than the preset current threshold value, the controller or the MCU controls the time relay to be out of work.
S110: and if the time relay works, acquiring the current working time of the time relay, and determining whether to control the controllable grounding switch assembly to be disconnected or not based on the current working time and a preset time threshold.
In one embodiment, if the time relay is controlled to operate, the current operating time of the time relay may be further obtained through the controller or the MCU, and whether to control the controllable grounding switch assembly to turn off is determined based on the current operating time and a preset time threshold. Specifically, the controller or the MCU records and obtains the current working time of the time relay, and compares the current working time with the preset time threshold set in advance to obtain a time difference comparison result.
In one embodiment, if the time difference comparison result is that the current working time is greater than or equal to the preset time threshold, it is proved that the current flowing through the conductor has fallen into a safe range at this time, that is, the controller or the MCU may control the controllable grounding switch assembly to be turned off. If the time difference comparison result shows that the current working time is smaller than the preset time threshold, it can be determined that the current flowing through the conductor is not reduced to a safe range at the moment, that is, the controller or the MCU does not control the controllable grounding switch assembly to be disconnected, and the controllable grounding switch assembly is continuously in a closed state. And simultaneously returning to the step S106 until the current working time is less than the preset time threshold.
In this embodiment, after the controllable grounding switch assembly is closed, whether to control the time relay to work can be determined based on the current effective value and the preset current threshold; if the time relay works, whether the controllable grounding switch assembly is controlled to be disconnected or not is further determined based on the current working time of the time relay and the preset time threshold value, so that the controllable grounding switch assembly can be effectively disconnected, potential safety hazards caused by misoperation are avoided, and safety and disconnection reliability are improved.
In one embodiment, the step of determining whether to control the controllable grounding switch assembly to be closed based on the voltage effective value and a preset voltage threshold value comprises: acquiring the preset voltage threshold, and comparing the preset voltage threshold with the voltage effective value to obtain a voltage comparison result; if the voltage comparison result shows that the voltage effective value is greater than or equal to the preset voltage threshold, controlling the controllable grounding switch component to be closed; and if the voltage comparison result shows that the effective voltage value is smaller than the preset voltage threshold, the controllable grounding switch component is not controlled to be closed.
In one embodiment, the preset voltage threshold and the voltage valid value may be compared by a difference value through the controller or the MCU. In one embodiment, the preset voltage threshold can be set according to the actual application scenario. In one embodiment, if the system generates a single-phase grounding and earth loss or non-full-phase operation power frequency overvoltage threatening the insulation of the neutral point of the transformer and the effective value of the voltage is greater than or equal to the preset voltage threshold value, the neutral point of the transformer can be prevented from being damaged by closing the controllable grounding switch assembly.
In one embodiment, the step of determining whether to control the operation of the time relay based on the effective current value and the preset current threshold value comprises: acquiring the preset current threshold, and comparing the preset current threshold with the current effective value to obtain a current comparison result; if the current comparison result shows that the current effective value is greater than or equal to the preset current threshold, controlling the time relay to work; and if the current comparison result shows that the effective current value is smaller than the preset current threshold, controlling the time relay to be out of work.
In one embodiment, the preset current threshold may be differentially compared to the current valid value by the controller or MCU. In one embodiment, the preset current threshold may be set according to an actual application scenario.
In one embodiment, if the time relay is operated, the step of obtaining the current operating time of the time relay, and determining whether to control the controllable grounding switch assembly to be turned off based on the current operating time and a preset time threshold value includes: if the time relay is controlled to work, the current working time of the time relay is obtained; and comparing the current working time with the preset time threshold value to obtain a time comparison result. And if the time comparison result shows that the current working time is greater than or equal to the preset time threshold, controlling the controllable grounding switch assembly to be switched off. And if the time comparison result shows that the current working time is less than the preset time threshold, the controllable grounding switch assembly is not controlled to be switched off.
In one embodiment, the difference comparison between the current working time and the preset time threshold may be performed by the controller or the MCU, and a difference comparison result is obtained. If the difference comparison result shows that the current working time is greater than or equal to the preset time threshold, the current flowing through the conductor is proved to be reduced to be within a safety range at the moment, namely the controller or the MCU can control the controllable grounding switch component to be switched off; otherwise, it may be determined that the current flowing through the conductor has not been reduced to the safe range, that is, the controller or the MCU does not control the controllable grounding switch assembly to be turned off, and then the process may return to step S106 until the current working time is less than the preset time threshold.
Referring to fig. 2 and 3, an embodiment of the present application provides a transformer neutral point protection device 10, including: conductor 100, controllable ground switch assembly 200, current transformer 300, controller 400, and time relay 500. The controllable earthing switch assembly 200 is electrically connected to the conductor 100. The current transformer 300 is electrically connected to the conductor 100. The controller 400 is electrically connected to the controllable earthing switch assembly 200 and the current transformer 300, respectively. The controller 400 is configured to perform the transformer neutral point protection method steps according to any of the embodiments. The time relay 500 is electrically connected to the controller 400.
In one embodiment, the time relay 500 may be integrated within the controller 400. In one embodiment, in order to avoid interference between the first transmission assembly 630 and the second transmission assembly 650 and facilitate maintenance, the first transmission assembly 630 and the second transmission assembly 650 are respectively disposed at two opposite sides of the output shaft 640. In one embodiment, the transformer neutral point protection device 10 further comprises: and a connection terminal 102. The controller 400 may be electrically connected to electrical components such as the controllable earthing switch assembly 200, the current transformer 300, and the like through the connection terminal 102, so as to facilitate control.
In one embodiment, the transformer neutral point protection device 10 further includes: closing the housing 700. The conductor 100 and the controllable earthing switch assembly 200 are both disposed within the closed housing 700. In one embodiment, the closure housing 700 may be a metal housing. In one embodiment, the enclosure 700 may be filled with pressure rated SF6A gas to seal the controllable earthing switch assembly 200 and the conductor, thereby securing an inner insulation performance. In one embodiment, the closed casing 700 may further be provided with a viewing window 701, and the viewing window 701 corresponds to the controllable grounding switch assembly 200, so as to facilitate viewing of the controllable grounding switch assembly 200.
In one embodiment, the transformer neutral point protection device 10 further includes: a transmission 600. The controller 400 controls the controllable earthing switch assembly 200 to be closed and opened through the transmission 600. Specifically, when the controller 400 executes the transformer neutral point protection method steps, if it is determined that the controllable earthing switch assembly 200 can be controlled to be turned off at this time, a control signal can be sent to the transmission device 600 through the time relay, so that the transmission device 600 controls the controllable earthing switch assembly 200 to be turned off.
Referring to fig. 4-6, in one embodiment, the transmission 600 includes: a fixed frame 610. And an active component 620 mounted on the fixing frame 610. And a first transmission assembly 630 connected with the active assembly 620. An output shaft 640 coupled to the first transmission assembly 630. A second transmission assembly 650 and the controllable earthing switch assembly 200 respectively connected with the output shaft 640. The second transmission assembly 650 includes a power spring 651, a first crank arm 652 connected to the output shaft 640, and a spring hanging unit 653 hinged to the first crank arm 652 and adapted to mount the power spring 651.
In one embodiment, when the transformer neutral point protection device 10 is in the initial state, the controllable earthing switch assembly 200 is in the first working position, and a discharge gap exists. When the system power frequency is over-voltage, the controller 400 sends a close control signal to the active device 620. The driving element 620 outputs a driving force to the first transmission element 630. The first transmission assembly 630 drives the output shaft 640 to rotate, so that the controllable earthing switch assembly 200 connected with the output shaft 640 is changed to the second working position. At this point the discharge gap is eliminated, the neutral point is grounded, and the active component 620 is locked.
Meanwhile, the output shaft 640 rotates in the first direction and drives the second transmission assembly 650 to move, that is, the first crank arm 652 is driven to rotate, so as to drive the energy storage spring 651 to stretch, thereby storing energy for the controllable earthing switch assembly 200 to change from the second station to the first station. When a gap is required to be generated by receiving a disconnection control signal, the locking force of the driving element 620 is removed, and the output shaft 640 indirectly connected with the driving element 620 is not bound. At this time, the energy storage spring 651 releases energy, and the energy storage spring is restored to a normal state from a stretched state, and drives the output shaft 640 to rotate in a second direction opposite to the first direction, so that the controllable earthing switch assembly 200 is changed from the second station to the first station, and at this time, a discharge gap is formed.
This embodiment not only realizes neutral point ground connection through initiative action, improves job stabilization nature, utilizes simultaneously energy storage spring 651 carries out the energy storage, and the power consumption is low, and connects through articulated transmission, simple structure, and energy loss is few. The present embodiment is only illustrated by the example that the controllable earthing switch assembly 200 is located at the first station in the initial state, that is, when there is a discharge gap, in other embodiments, the initial state may also be that the controllable earthing switch assembly 200 is located at the second station, and the operation principle is similar to that described above. In this embodiment, the transformer neutral point protection device 10 adopts an active action of a mechanical structure to replace a traditional passive gap breakdown, and when a power frequency overvoltage occurs in a system, the active action realizes neutral point grounding, so that a fault is eliminated, the defect that the gap breakdown of the traditional transformer neutral point protection device is insensitive or malfunctions is effectively overcome, and the working stability is greatly improved.
Referring to fig. 5, in one embodiment, the hanging spring unit 653 includes: a first hanging spring plate 654 hinged with the first crank arm 652, and a second hanging spring plate 655 arranged at a distance from the first hanging spring plate 654, wherein the energy storage spring 651 is arranged between the first hanging spring plate 654 and the second hanging spring plate 655.
In one embodiment, the second hanging spring plate 655 is connected to the fixed frame 610, so that when the first hanging spring plate 654 moves along with the rotation of the first crank arm 652, the second hanging spring plate 655 is fixed, thereby the energy storage spring 651 connected between the first hanging spring plate 654 and the second hanging spring plate 655 is extended to store energy.
In one embodiment, the hanging spring unit 653 further comprises: and an adjusting unit 660 for adjusting the amount of extension of the energy storage spring 51. The adjusting unit 660 is connected to the second hanger spring plate 655. Specifically, the second suspension spring plate 655 is connected to the fixing frame 610 through the adjusting unit 660. The amount of pretension or the amount of stretching of the energy storage spring 651 can be adjusted by the adjusting unit 660, so that the required work requirement can be met.
In one embodiment, the adjusting unit 660 further includes: a screw 661 connected with the second hanger spring plate 655, and a nut 662 engaged with the screw 661. The fixing frame 610 is provided with a through hole for penetrating the screw 661. Specifically, the fixing frame 610 includes a fixing plate 611 engaged with the screw 661 and the nut 662. The through hole is formed in the fixing plate 611. One end of the screw 661 is connected to the second suspension spring plate 655, and the other end of the screw 661 penetrates through the through hole and extends out of the fixing plate 611, and the screw 661 is fixed by the nut 662. The amount of tension or pretension of the energy storage spring 651 is adjusted by adjusting the length of the screw 661 extending out of the fixing plate 611.
Referring to fig. 6, in one embodiment, the controllable grounding switch assembly 200 includes: a stationary contact 210 and a movable contact 220. The stationary contact 210 is electrically connected to the conductor 100. The movable contact 220 is connected to the transmission device 600. The controller 400 controls the moving contact 220 to contact with and separate from the fixed contact 210 through the transmission device 600. In one embodiment, the controllable grounding switch assembly 200 further comprises: a switch crank arm 230 and an auxiliary link 240. The movable contact 220 is connected to the transmission device 600 through the switch crank arm 230. The auxiliary link 240 is respectively hinged to the switch crank arm 230 and the output shaft 640.
In one embodiment, the movable contact 220 and the fixed contact 210 form a discharge gap in an initial position, that is, are located at a switching-off position (i.e., the controllable grounding switch assembly 200 is turned off). When the neutral point grounding needs to be realized, the energy storage spring 651 releases energy to drive the output shaft 640 to rotate, and then the auxiliary connecting rod 240 hinged with the output shaft 640 is driven to swing. The auxiliary link 240 drives the switch crank arm 230 connected thereto to rotate, so that the movable contact 220 connected to the switch crank arm 230 moves to contact with the stationary contact 210, the discharge gap is eliminated, the movable contact is located at a closing station (i.e., closed), and a neutral point is grounded (i.e., the neutral point is electrically connected to the ground terminal 101).
In one embodiment, the first transmission assembly 630 includes a first link 631 connected to the active assembly 620, and a second link 632 hinged to the first link 631. The second crank arm 632 is connected to the output shaft 640. When switching-off and switching-on conditions of the controllable grounding switch assembly 200 need to be changed, the driving assembly 620 drives the first connecting rod 631 to move, so as to drive the output shaft 640 indirectly connected with the first connecting rod 631 to rotate, thereby realizing control of the controllable grounding switch assembly 200.
In one embodiment, the driving assembly 620 includes a driving member 621, an output crank arm 622 connected to the driving member 621, and a locking member (not shown) for locking the output crank arm 622 and connected to the driving member 621. The output crank arm 622 is hinged to the first link 631. In one embodiment, the driving member 621 is a motor. The driving member 621 drives the output crank arm 622 to swing, so as to drive the first connecting rod 631 to move left and right, and indirectly drive the output shaft 640 to rotate. The retaining member is used in that: when the controllable grounding switch assembly is in an opening or closing state, the locking piece locks the output crank arm 622 so that the output crank arm does not move any more until the locking action is removed after a signal is received. At this time, the energy storage spring 651 loses the limit of the output shaft 640, and can release energy to drive the output shaft 640 to rotate and indirectly drive the output crank arm 622 to rotate to the switched station.
In one embodiment, both ends of the first link 31 are connected to the output crank arm 622 and the second crank arm 632 through joints 633, respectively. One end of the joint 633 is hinged to the output crank arm 622 and the second crank arm 632 respectively. The other end of the joint 633 is a threaded hole. First connecting rod 631 is equipped with the screw through both ends, joint 633 with first connecting rod 631 threaded connection to first connecting rod 631 can be dismantled, is convenient for change the maintenance on the one hand, on the other hand also can be according to actual conditions use different length first connecting rod 631 realizes the conveying of different distances or angle, thereby enlarges the application range of this device.
In one embodiment, the fixing frame 610 is provided with a bearing seat 641 for limiting the output shaft 640. The output shaft 640 is disposed in the bearing seat 641, and a bearing is disposed between the bearing seat 641 and the output shaft 640, so that the output shaft 640 can be axially limited, and circumferential rotation of the output shaft 640 is not affected.
In summary, the time relay can be determined whether to control the time relay to work or not based on the current effective value and the preset current threshold value after the controllable grounding switch assembly is closed; if the time relay works, whether the controllable grounding switch assembly is controlled to be disconnected or not is further determined based on the current working time of the time relay and the preset time threshold value, so that the controllable grounding switch assembly can be effectively disconnected, potential safety hazards caused by misoperation are avoided, and safety and disconnection reliability are improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. A transformer neutral point protection method is applied to a transformer neutral point protection device, and comprises the following steps:
acquiring three-phase voltage of a bus to obtain a voltage effective value;
determining whether to control the controllable grounding switch assembly to be closed or not based on the voltage effective value and a preset voltage threshold value;
if the controllable grounding switch component is closed, acquiring the current of the secondary side of the current transformer electrically connected with the conductor to obtain a current effective value;
determining whether to control the time relay to work or not based on the current effective value and a preset current threshold value;
and if the time relay works, acquiring the current working time of the time relay, and determining whether to control the controllable grounding switch assembly to be disconnected or not based on the current working time and a preset time threshold.
2. The method for protecting the neutral point of the transformer according to claim 1, wherein the step of obtaining the three-phase voltage of the bus to obtain the effective voltage value comprises the following steps:
and acquiring the three-phase voltage of the bus through a voltage transformer, and obtaining the effective voltage value.
3. The transformer neutral point protection method of claim 1, wherein the step of determining whether to control the controllable grounding switch assembly to be closed based on the voltage effective value and a preset voltage threshold value comprises:
acquiring the preset voltage threshold, and comparing the preset voltage threshold with the voltage effective value to obtain a voltage comparison result;
if the voltage comparison result shows that the voltage effective value is greater than or equal to the preset voltage threshold, controlling the controllable grounding switch component to be closed;
and if the voltage comparison result shows that the effective voltage value is smaller than the preset voltage threshold, the controllable grounding switch component is not controlled to be closed.
4. The transformer neutral point protection method of claim 1, wherein the step of determining whether to control the operation of the time relay based on the current effective value and a preset current threshold value comprises:
acquiring the preset current threshold, and comparing the preset current threshold with the current effective value to obtain a current comparison result;
if the current comparison result shows that the current effective value is greater than or equal to the preset current threshold, controlling the time relay to work;
and if the current comparison result shows that the effective current value is smaller than the preset current threshold, controlling the time relay to be out of work.
5. The transformer neutral point protection method of claim 1, wherein the step of obtaining a current operation time of the time relay if the time relay operates, and determining whether to control the controllable grounding switch assembly to be turned off based on the current operation time and a preset time threshold comprises:
if the time relay works, the current working time of the time relay is obtained;
comparing the current working time with the preset time threshold to obtain a time comparison result;
if the time comparison result shows that the current working time is greater than or equal to the preset time threshold, controlling the controllable grounding switch assembly to be switched off;
and if the time comparison result shows that the current working time is less than the preset time threshold, the controllable grounding switch assembly is not controlled to be switched off.
6. A transformer neutral point protection device, comprising:
a conductor (100);
a controllable ground switch assembly (200) electrically connected to the conductor (100);
a current transformer (300) electrically connected to the conductor (100);
a controller (400) electrically connected to the controllable earthing switch assembly (200) and the current transformer (300), respectively, for performing the transformer neutral point protection method steps according to any one of claims 1-5; and
a time relay (500) electrically connected to the controller (400).
7. The transformer neutral point protection device of claim 6, further comprising:
a transmission (600), the controller (400) controlling the controllable grounding switch assembly (200) to be closed and opened through the transmission (600).
8. A transformer neutral point protection arrangement according to claim 7, characterized in that the transmission arrangement (600) comprises:
the controllable grounding switch comprises a fixed frame (610), a driving component (620) arranged on the fixed frame (610), a first transmission component (630) connected with the driving component (620), an output shaft (640) connected with the first transmission component (630), a second transmission component (650) and the controllable grounding switch component (200) which are respectively connected with the output shaft (640);
the second transmission assembly (650) comprises an energy storage spring (651), a first crank arm (652) connected with the output shaft (640), and a spring hanging unit (653) hinged with the first crank arm (652) and used for installing the energy storage spring (651).
9. The transformer neutral point protection device of claim 8, wherein the hanging spring unit (653) comprises: the energy storage device comprises a first hanging spring plate (654) hinged with the first crank arm (652) and a second hanging spring plate (655) arranged at intervals with the first hanging spring plate (654), wherein the energy storage spring (651) is arranged between the first hanging spring plate (654) and the second hanging spring plate (655).
10. A transformer neutral protection arrangement according to any one of claims 6-7, characterized in that the controllable earthing switch assembly (200) comprises:
a stationary contact (210) electrically connected to the conductor (100);
the moving contact (220) is connected with the transmission device (600), and the controller (400) controls the moving contact (220) to be in contact with or separated from the fixed contact (210) through the transmission device (600).
11. The transformer neutral point protection device of claim 6, further comprising:
a closed housing (700), the conductor (100) and the controllable earthing switch assembly (200) being disposed within the closed housing (700).
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| CN201911132555.0A CN111030049B (en) | 2019-11-19 | 2019-11-19 | Transformer neutral point protection method and device |
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| CN201911132555.0A CN111030049B (en) | 2019-11-19 | 2019-11-19 | Transformer neutral point protection method and device |
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Cited By (1)
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| CN114158781A (en) * | 2021-10-27 | 2022-03-11 | 海南摩尔兄弟科技有限公司 | Electronic device, battery pole applying same and electronic atomization device |
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