CN113178794B - Zero sequence overcurrent protection method for spare power automatic switching triggering circuit of high-voltage built-in transformer - Google Patents
Zero sequence overcurrent protection method for spare power automatic switching triggering circuit of high-voltage built-in transformer Download PDFInfo
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- CN113178794B CN113178794B CN202110544006.5A CN202110544006A CN113178794B CN 113178794 B CN113178794 B CN 113178794B CN 202110544006 A CN202110544006 A CN 202110544006A CN 113178794 B CN113178794 B CN 113178794B
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
- H02B1/00—Frameworks, boards, panels, desks, casings; Details of substations or switching arrangements
- H02B1/26—Casings; Parts thereof or accessories therefor
- H02B1/46—Boxes; Parts thereof or accessories therefor
- H02B1/48—Mounting of devices therein
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
- H02B1/00—Frameworks, boards, panels, desks, casings; Details of substations or switching arrangements
- H02B1/015—Boards, panels, desks; Parts thereof or accessories therefor
- H02B1/04—Mounting thereon of switches or of other devices in general, the switch or device having, or being without, casing
- H02B1/052—Mounting on rails
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
- H02H3/34—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors of a three-phase system
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/007—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources
- H02J3/0073—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources for providing alternative feeding paths between load and source when the main path fails, e.g. transformers, busbars
Abstract
The invention discloses a zero sequence overcurrent protection method for a spare power automatic switching triggering circuit of a high-voltage built-in transformer, which comprises a handle, a first rack, a gear, a second rack, a second spring and a second limit groove; the protection method comprises the following steps of firstly, collecting data; step two, automatic switching is started; step three, setting a zero sequence overcurrent protection criterion; judging a short line of the current transformer; judging the effective value of the three-phase current; step six, resetting the transformer; the invention is safe and reliable, and the false operation of the zero sequence overcurrent protection device and the safe and stable operation of the power grid are avoided by setting the protection criterion of the zero sequence overcurrent protection device, judging whether the current transformer is broken or not and judging the three-phase current effective value; the zero-sequence overcurrent protection method for the spare power automatic switching triggering circuit of the high-voltage built-in transformer does not change the original zero-sequence overcurrent protection strategy, can be realized on the existing platform, and is convenient to popularize and use.
Description
Technical Field
The invention relates to the technical field of power grid relay protection, in particular to a zero sequence overcurrent protection method for a spare power automatic switching triggering circuit of a high-voltage built-in transformer.
Background
Along with the continuous development of economy, the requirements of a power system on the power supply reliability are higher and higher, and the spare power automatic switching as one of important methods for maintaining the power supply continuity of a power grid and improving the power supply reliability is started to be applied to substations of 330kV and above, so that a zero sequence overcurrent protection method of a spare power automatic switching initiation circuit of a high-voltage built-in transformer on the market has certain requirements; however, the existing zero-sequence overcurrent protection mode is simpler, the zero-sequence overcurrent protection misoperation is easy to occur, the operation failure of the standby power supply is caused, and the power supply of the load connected to the downstream of the transformer substation cannot be recovered in time; the existing spare power automatic switching device is mostly fixed on the temporal part of the power distribution cabinet in a bolt connection mode, so that the spare power automatic switching device is inconvenient to detach, maintain and replace; therefore, it is very necessary to invent a zero sequence overcurrent protection method for a spare power automatic switching triggering circuit of a high-voltage built-in transformer at the present stage.
Disclosure of Invention
The invention aims to provide a zero sequence overcurrent protection method for a spare power automatic switching initiation circuit of a high-voltage built-in transformer, which aims to solve the problems that the zero sequence overcurrent protection misoperation and spare power automatic switching equipment are inconvenient to detach and maintain in the background technology.
In order to solve the technical problems, the invention provides the following technical scheme: the utility model provides a zero sequence overcurrent protection device of circuit is triggered to high pressure built-in transformer spare power automatic switching, includes block terminal, guide rail, spare power automatic switching body, first spout, second spout, handle, first rack, first spacing groove, stopper, first spring, axis of rotation, gear, third spout, second rack, second spring, connecting axle and second spacing groove, be provided with the spare power automatic switching body on one side inner wall of block terminal, the second spout has been seted up to the symmetry on one side inner wall of spare power automatic switching body, sliding connection has the handle on one side inner wall of second spout, fixedly connected with first rack on symmetrical both ends of handle, and first rack sliding connection is in the inside of second spout, cup joint first spring on one side outer wall of first rack, the distribution is rotated on one side inner wall of spare power automatic switching body and is connected with the axis of rotation, fixedly connected with gear on one side outer wall of axis of rotation, and gear engagement is connected on one side outer wall of first rack, the distribution has seted up the third spout on one side inner wall of spare power automatic switching body, on one side inner wall fixedly connected with first rack on the first rack of second rack, on the outer wall of first rack engagement.
Preferably, the inner wall of block terminal is last to distribute symmetry fixedly connected with guide rail, first spout has been seted up to the distribution symmetry on the outer wall of spare power automatic switching body, and guide rail sliding connection is in the inside of first spout.
Preferably, a first limit groove is distributed on the inner wall of one side of the spare power automatic switching body, a limit block is fixedly connected to the outer wall of one end of the first rack, and the limit block is slidably connected to the inside of the first limit groove.
Preferably, a second spring is fixedly connected to the inner wall of one side of the third sliding groove, and one end of the second spring is fixedly connected to the outer wall of one end of the second rack.
Preferably, a connecting shaft is fixedly connected to the outer wall of one end of the second rack, second limiting grooves are distributed on the inner wall of the distribution box, and the connecting shaft is slidably connected to the inside of the second limiting grooves.
A zero sequence overcurrent protection method for a high-voltage built-in type transformer spare power automatic switching triggering circuit comprises the following steps of firstly, data acquisition; step two, automatic switching is started; step three, setting a zero sequence overcurrent protection criterion; judging a short line of the current transformer; judging the effective value of the three-phase current; and step six, resetting the transformer.
In the first step, three-phase currents on the lines before and after the automatic backup power switching body acts are collected in real time, and a line zero-sequence current sampling sequence is calculated according to the collected three-phase current data.
In the second step, when the ground fault occurs, the spare power automatic switching body is automatically started, the main line of the transformer is automatically disconnected, then a spare power automatic switching body device line zero sequence inrush current identification criterion is constructed according to the line zero sequence current sampling sequence data in the first step, identification judgment is carried out, if the identification result is a non-inrush current working condition, the line zero sequence overcurrent protection is not locked, and if the identification result is an inrush current working condition, the zero sequence overcurrent protection is locked.
In the third step, the zero-mode inrush current parameter of the transformer is obtained through the line zero-sequence current sampling sequence calculated in the first step, then the zero-mode inrush current parameter and the zero-mode inrush current analysis of the transformer are utilized to obtain a zero-mode inrush current waveform, and finally the obtained zero-mode inrush current waveform is utilized to serve as a protection criterion of the zero-sequence overcurrent protection device.
In the fourth step, firstly, judging whether the zero-sequence overcurrent protection starting is met or not according to the protection criterion of the zero-sequence overcurrent protection device obtained in the third step, if so, starting the zero-sequence overcurrent protection, and if not, locking the zero-sequence overcurrent protection; judging whether the current transformer is broken or not, if the current transformer is not broken and the second harmonic content in the neutral point zero sequence current of the transformer is greater than a second harmonic content fixed value and the neutral point zero sequence current waveform of the transformer is saturated, opening the zero sequence overcurrent protection of the transformer after the time T is set; if CT has no broken line, and the second harmonic content in the neutral point zero sequence current of the transformer is not more than the second harmonic content fixed value or the zero sequence current waveform of the transformer is unsaturated, the current zero sequence overcurrent protection of the transformer is immediately opened.
In the fifth step, the three-phase current effective value is obtained, and whether the maximum value of the three-phase current effective value is greater than the first preset value of the zero-sequence protection current is judged, if the maximum value of the three-phase current effective value is smaller than or equal to the preset value of the zero-sequence protection current, the zero-sequence overcurrent protection is kept in the existing state, and if the maximum value of the three-phase current effective value is greater than the preset value of the zero-sequence protection current, the zero-sequence overcurrent protection is opened.
In the sixth step, maintenance personnel repair the earth leakage fault of the circuit, recover the main circuit of the transformer, and after the repair is finished, the spare power automatic switching body is automatically disconnected, and the zero sequence overcurrent protection automatically recovers the original state.
Preferably, in the first step, three-phase current is collected through a current transformer.
Preferably, in the second step, when the spare power automatic switching body is started, an indication signal is sent out.
Preferably, in the third step, the zero-mode inrush current analysis method includes saturation mutual inductance of the transformer, high-voltage side self-leakage reactance, low-voltage side self-leakage reactance, system zero-sequence reactance, system voltage, system magnetic density, unsaturated iron core magnetic density and residual magnetic density.
Preferably, in the fourth step, the method for judging that the current transformer has no disconnection is that the three-phase self-generated zero-sequence voltage amplitude of the current transformer is greater than the zero-sequence overvoltage fixed value, and the zero-sequence current amplitude of the neutral point of the current transformer is greater than the secondary rated value of the current transformer.
Preferably, in the fifth step, a fourier analysis method is adopted to obtain the three-phase current effective value.
Compared with the prior art, the invention has the following beneficial effects: the invention is safe and reliable, and the false operation of the zero sequence overcurrent protection device and the safe and stable operation of the power grid are avoided by setting the protection criterion of the zero sequence overcurrent protection device, judging whether the current transformer is broken or not and judging the three-phase current effective value; the zero-sequence overcurrent protection is controlled not to be opened within the set time T, so that the malfunction of the zero-sequence overcurrent protection of the transformer can be effectively avoided, and meanwhile, the malfunction of the zero-sequence overcurrent protection of the transformer caused by zero-sequence current when the current transformer is disconnected can be avoided, and the safe and stable operation of a power grid is ensured; the zero sequence overcurrent protection method of the spare power automatic switching triggering circuit of the high-voltage built-in transformer does not change the original zero sequence overcurrent protection strategy, can be realized on the existing platform, and is convenient to popularize and use; through the cooperation of handle, first rack, stopper, first spring, gear, second rack, second spring and second spacing groove, simple structure will be equipped with the automatic switching equipment block inside the switch board through the spring block structure that hidden handle is connected, realize stable installation, and convenient to detach's purpose.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate the invention and together with the embodiments of the invention, serve to explain the invention. In the drawings:
fig. 1 is a schematic view of the overall front cut-away structure of the present invention.
Fig. 2 is a schematic diagram of a side view partially cut-away structure of the spare power automatic switching device body of the present invention.
FIG. 3 is a schematic view of the present invention in a partially cut-away top view.
Fig. 4 is a schematic perspective view of a second rack according to the present invention.
Fig. 5 is a schematic perspective view of the handle of the present invention.
Fig. 6 is an enlarged view of the structure of the area a in fig. 1 according to the present invention.
Fig. 7 is a flow chart of the method of the present invention.
In the figure: 1. a distribution box; 2. a guide rail; 3. a spare power automatic switching body; 4. a first chute; 5. a second chute; 6. a handle; 7. a first rack; 8. a first limit groove; 9. a limiting block; 10. a first spring; 11. a rotating shaft; 12. a gear; 13. a third chute; 14. a second rack; 15. a second spring; 16. a connecting shaft; 17. and the second limit groove.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1-6, the present invention provides a technical solution: the zero sequence overcurrent protection device for the high-voltage built-in type transformer standby automatic switching triggering circuit comprises a distribution box 1, a guide rail 2, a standby automatic switching body 3, a first sliding groove 4, a second sliding groove 5, a handle 6, a first rack 7, a first limit groove 8, a limit block 9, a first spring 10, a rotating shaft 11, a gear 12, a third sliding groove 13, a second rack 14, a second spring 15, a connecting shaft 16 and a second limit groove 17, wherein the standby automatic switching body 3 is arranged on one side inner wall of the distribution box 1, the second sliding groove 5 is symmetrically arranged on one side inner wall of the standby automatic switching body 3, the handle 6 is slidingly connected on one side inner wall of the second sliding groove 5, the first racks 7 are symmetrically fixedly connected with the first racks 7 at two ends of the handle 6, the first racks 7 are slidingly connected inside the second sliding groove 5, the first springs 10 are sleeved on one side outer wall of the first racks 7, the rotating shaft 11 is rotationally connected on one side inner wall of the standby automatic switching body 3, the gear 12 is fixedly connected with the rotating shaft 12 on one side outer wall of the rotating shaft, the gear 12 is meshed with the first sliding groove 13 on one side of the outer wall of the first sliding groove 7, the third sliding groove 13 is connected with the third sliding groove 14 on one side of the inner wall of the first sliding groove 13; the inner wall of the distribution box 1 is symmetrically and fixedly connected with a guide rail 2, the outer wall of the spare power automatic switching body 3 is symmetrically provided with a first chute 4, and the guide rail 2 is in sliding connection with the inside of the first chute 4; a first limit groove 8 is distributed on the inner wall of one side of the spare power automatic switching body 3, a limit block 9 is fixedly connected to the outer wall of one end of the first rack 7, and the limit block 9 is slidably connected to the inside of the first limit groove 8; a second spring 15 is fixedly connected to the inner wall of one side of the third chute 13, and one end of the second spring 15 is fixedly connected to the outer wall of one end of the second rack 14; the connecting shaft 16 is fixedly connected to the outer wall of one end of the second rack 14, the second limiting grooves 17 are distributed on the inner wall of the distribution box 1, and the connecting shaft 16 is slidably connected to the inside of the second limiting grooves 17.
Referring to fig. 7, the present invention provides a technical solution: a zero sequence overcurrent protection method for a high-voltage built-in type transformer spare power automatic switching triggering circuit comprises the following steps of firstly, data acquisition; step two, automatic switching is started; step three, setting a zero sequence overcurrent protection criterion; judging a short line of the current transformer; judging the effective value of the three-phase current; and step six, resetting the transformer.
In the first step, three-phase currents on the lines before and after the automatic backup power switching body 3 acts are collected in real time through a current transformer, and a line zero-sequence current sampling sequence is calculated according to the collected three-phase current data.
In the second step, when the ground fault occurs, the spare power automatic switching body 3 is automatically started, an indication signal is sent out, meanwhile, the main circuit of the transformer is automatically disconnected, then, a zero sequence inrush current identification criterion of the spare power automatic switching body 3 device circuit is built according to the zero sequence current sampling sequence data of the first circuit, identification judgment is carried out, if the identification result is a non-inrush current working condition, the zero sequence overcurrent protection of the circuit is not locked, and if the identification result is an inrush current working condition, the zero sequence overcurrent protection is locked.
In the third step, the zero-mode inrush current parameter of the transformer is obtained through the line zero-sequence current sampling sequence calculated in the first step, then the zero-mode inrush current parameter and the zero-mode inrush current analytic type of the transformer are utilized to obtain a zero-mode inrush current waveform, and finally the obtained zero-mode inrush current waveform is utilized as a protection criterion of the zero-sequence overcurrent protection device, wherein the zero-mode inrush current analytic type comprises the saturation mutual inductance, the high-voltage side self-leakage reactance, the low-voltage side self-leakage reactance, the system zero-sequence reactance, the system voltage, the system magnetic flux density, the unsaturated iron core magnetic flux density and the magnetic flux density of the residual magnetism of the transformer.
In the fourth step, firstly, judging whether the zero-sequence overcurrent protection starting is met or not according to the protection criterion of the zero-sequence overcurrent protection device obtained in the third step, if so, starting the zero-sequence overcurrent protection, and if not, locking the zero-sequence overcurrent protection; judging whether the current transformer is broken or not, if the current transformer is not broken and the second harmonic content in the neutral point zero sequence current of the transformer is greater than a second harmonic content fixed value and the neutral point zero sequence current waveform of the transformer is saturated, opening the zero sequence overcurrent protection of the transformer after the time T is set; if the CT is not broken, the second harmonic content in the neutral point zero-sequence current of the transformer is not more than a second harmonic content fixed value or the zero-sequence current waveform of the neutral point of the transformer is unsaturated, the current transformer is immediately opened for zero-sequence overcurrent protection, and the method for judging that the current transformer is not broken is that the three-phase self-produced zero-sequence voltage amplitude of the transformer is more than a zero-sequence overvoltage fixed value and the zero-sequence current amplitude of the neutral point of the transformer is more than a secondary rated value of the current transformer.
In the fifth step, the three-phase current effective value is obtained, whether the maximum value of the three-phase current effective value is larger than the first preset value of the zero-sequence protection current is judged, the three-phase current effective value is obtained by adopting a fourier analysis method, if the maximum value of the three-phase current effective value is smaller than or equal to the preset value of the zero-sequence protection current, the zero-sequence overcurrent protection is kept in the existing state, and if the maximum value of the three-phase current effective value is larger than the preset value of the zero-sequence protection current, the zero-sequence overcurrent protection is opened.
In the sixth step, maintenance personnel repair the earth leakage fault of the line, recover the main circuit of the transformer, and after the repair is finished, the spare power automatic switching body 3 is automatically disconnected, and the zero sequence overcurrent protection automatically recovers the original state.
Based on the above, the invention has the advantages that the invention is safe and reliable, the zero sequence overcurrent protection method of the high-voltage built-in type transformer spare power automatic switching triggering circuit adopts three judgment methods of setting the protection criterion of the zero sequence overcurrent protection device, judging whether the current transformer is disconnected or not and judging the three-phase current effective value, thereby preventing the malfunction of the zero sequence overcurrent protection device under various conditions and facilitating the safe and stable operation of the power grid; the method can be used on the original platform, and is convenient to popularize and use; when the spare power automatic switching body 3 is damaged or needs to be maintained and replaced, the handle 6 is manually pulled to drive the first rack 7 to move, so that the first spring 10 is compressed, the gear 12 is driven to rotate under the action of the first rack 7, the second rack 14 is driven to move under the action of the gear 12, the connecting shaft 16 on the second rack 14 is separated from the second limiting groove 17, and the handle 6 is continuously pulled to take out the spare power automatic switching body 3.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (1)
1. The utility model provides a zero sequence overcurrent protection device of high-voltage built-in transformer spare power automatic switching initiation circuit, including block terminal (1), guide rail (2), spare power automatic switching body (3), first spout (4), second spout (5), handle (6), first rack (7), first spacing groove (8), stopper (9), first spring (10), axis of rotation (11), gear (12), third spout (13), second rack (14), second spring (15), connecting axle (16) and second spacing groove (17), its characterized in that: the automatic switching device is characterized in that a spare power automatic switching body (3) is arranged on one side inner wall of the distribution box (1), a second sliding groove (5) is symmetrically formed in one side inner wall of the spare power automatic switching body (3), a handle (6) is connected to one side inner wall of the second sliding groove (5) in a sliding mode, a first rack (7) is fixedly connected to two ends of the handle (6) in a symmetrical mode, the first rack (7) is connected to the inside of the second sliding groove (5) in a sliding mode, a first spring (10) is sleeved on one side outer wall of the first rack (7), rotating shafts (11) are connected to one side inner wall of the spare power automatic switching body (3) in a distributed mode, gears (12) are fixedly connected to one side outer wall of the rotating shafts (11), a third sliding groove (13) is formed in a distributed mode in one side inner wall of the spare power automatic switching body (3), and the gears (12) are connected to one side outer wall of the first rack (14) in a meshed mode;
the automatic switching system is characterized in that guide rails (2) are symmetrically and fixedly connected to the inner wall of the distribution box (1), first sliding grooves (4) are symmetrically formed in the outer wall of the automatic switching body (3), and the guide rails (2) are slidably connected to the inner parts of the first sliding grooves (4);
a first limit groove (8) is distributed on the inner wall of one side of the spare power automatic switching body (3), a limit block (9) is fixedly connected to the outer wall of one end of the first rack (7), and the limit block (9) is slidably connected to the inside of the first limit groove (8);
a second spring (15) is fixedly connected to the inner wall of one side of the third sliding groove (13), and one end of the second spring (15) is fixedly connected to the outer wall of one end of the second rack (14);
a connecting shaft (16) is fixedly connected to the outer wall of one end of the second rack (14), second limit grooves (17) are distributed on the inner wall of the distribution box (1), and the connecting shaft (16) is slidably connected to the inside of the second limit grooves (17);
the zero sequence overcurrent protection method for the high-voltage built-in type transformer spare power automatic switching triggering circuit zero sequence overcurrent protection device comprises the following steps of firstly, data acquisition; step two, automatic switching is started; step three, setting a zero sequence overcurrent protection criterion; judging a short line of the current transformer; judging the effective value of the three-phase current; step six, resetting the transformer; the method is characterized in that:
in the first step, three-phase currents on the lines before and after the automatic backup power switching body (3) acts are collected in real time, and a line zero-sequence current sampling sequence is calculated according to the collected three-phase current data;
in the second step, when a ground fault occurs, the spare power automatic switching body (3) is automatically started, the main circuit of the transformer is automatically disconnected, then a zero sequence inrush current identification criterion of a device circuit of the spare power automatic switching body (3) is constructed according to the zero sequence current sampling sequence data of the circuit in the first step, identification judgment is carried out, if the identification result is a non-inrush current working condition, the zero sequence overload protection of the circuit is not blocked, and if the identification result is an inrush current working condition, the zero sequence overload protection is blocked;
in the third step, firstly, the zero-mode inrush current parameter of the transformer is obtained through the line zero-sequence current sampling sequence calculated in the first step, then the zero-mode inrush current parameter and the zero-mode inrush current analysis of the transformer are utilized to obtain a zero-mode inrush current waveform, and finally the obtained zero-mode inrush current waveform is utilized as a protection criterion of the zero-sequence overcurrent protection device;
in the fourth step, firstly, judging whether the zero-sequence overcurrent protection starting is met or not according to the protection criterion of the zero-sequence overcurrent protection device obtained in the third step, if so, starting the zero-sequence overcurrent protection, and if not, locking the zero-sequence overcurrent protection; judging whether the current transformer is broken or not, if the current transformer is not broken and the second harmonic content in the neutral point zero sequence current of the transformer is greater than a second harmonic content fixed value and the neutral point zero sequence current waveform of the transformer is saturated, opening the zero sequence overcurrent protection of the transformer after the time T is set; if CT has no broken line, and the second harmonic content in the neutral point zero sequence current of the transformer is not more than the second harmonic content fixed value or the zero sequence current waveform of the transformer is unsaturated, immediately opening the zero sequence overcurrent protection of the transformer;
in the fifth step, a three-phase current effective value is obtained, whether the maximum value of the three-phase current effective value is larger than a first preset value of the zero-sequence protection current is judged, if the maximum value of the three-phase current effective value is smaller than or equal to the preset value of the zero-sequence protection current, the zero-sequence overcurrent protection is kept in the existing state, and if the maximum value of the three-phase current effective value is larger than the preset value of the zero-sequence protection current, the zero-sequence overcurrent protection is opened;
in the step six, maintenance personnel repair the earth leakage fault of the circuit, recover the main circuit of the transformer, and after the repair is finished, the spare power automatic switching body (3) is automatically disconnected, and the zero sequence overcurrent protection automatically recovers the original state;
in the first step, three-phase current is collected through a current transformer;
in the second step, when the spare power automatic switching body (3) is started, an indication signal is sent out;
in the third step, zero-mode inrush current analysis comprises saturation mutual inductance of the transformer, high-voltage side self-leakage reactance, low-voltage side self-leakage reactance, system zero-sequence reactance, system voltage, system magnetic density, unsaturated iron core magnetic density and residual magnetic density;
in the fourth step, the method for judging that the current transformer is not broken is that the amplitude of the three-phase self-generated zero-sequence voltage on the primary side of the transformer is larger than the zero-sequence overvoltage fixed value, and the amplitude of the zero-sequence current on the neutral point on the primary side of the transformer is larger than the secondary rated value of the current transformer;
in the fifth step, a Fourier analysis method is adopted to obtain the three-phase current effective value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110544006.5A CN113178794B (en) | 2021-05-19 | 2021-05-19 | Zero sequence overcurrent protection method for spare power automatic switching triggering circuit of high-voltage built-in transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110544006.5A CN113178794B (en) | 2021-05-19 | 2021-05-19 | Zero sequence overcurrent protection method for spare power automatic switching triggering circuit of high-voltage built-in transformer |
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| Publication Number | Publication Date |
|---|---|
| CN113178794A CN113178794A (en) | 2021-07-27 |
| CN113178794B true CN113178794B (en) | 2023-09-01 |
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| CN202110544006.5A Active CN113178794B (en) | 2021-05-19 | 2021-05-19 | Zero sequence overcurrent protection method for spare power automatic switching triggering circuit of high-voltage built-in transformer |
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| AU6693990A (en) * | 1989-11-24 | 1991-05-30 | Siemens Aktiengesellschaft | Electrical switchgear having an insertable and retractable apparatus rack |
| DE19748553A1 (en) * | 1997-11-04 | 1999-05-20 | Aeg Starkstrom Anlagenbau Magd | Push-in module for electrical switching gear |
| CN109119971A (en) * | 2018-09-03 | 2019-01-01 | 广东电网有限责任公司 | zero-sequence over-current protection method, system, device and computer readable storage medium |
| CN110556783A (en) * | 2019-09-10 | 2019-12-10 | 许昌许继软件技术有限公司 | zero sequence overcurrent protection method and device for transformer |
| CN210628922U (en) * | 2019-11-06 | 2020-05-26 | 珠海德鑫电气设备有限公司 | Hand-pulling mechanism for drawer of low-voltage switch cabinet |
| CN111711180A (en) * | 2020-06-19 | 2020-09-25 | 国网宁夏电力有限公司 | Method and system for preventing zero sequence overcurrent protection misoperation of ultrahigh voltage spare power automatic switching induced circuit |
| CN212277666U (en) * | 2020-06-16 | 2021-01-01 | 张志霞 | Electric power low-voltage switch cabinet |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| AU6693990A (en) * | 1989-11-24 | 1991-05-30 | Siemens Aktiengesellschaft | Electrical switchgear having an insertable and retractable apparatus rack |
| DE19748553A1 (en) * | 1997-11-04 | 1999-05-20 | Aeg Starkstrom Anlagenbau Magd | Push-in module for electrical switching gear |
| CN109119971A (en) * | 2018-09-03 | 2019-01-01 | 广东电网有限责任公司 | zero-sequence over-current protection method, system, device and computer readable storage medium |
| CN110556783A (en) * | 2019-09-10 | 2019-12-10 | 许昌许继软件技术有限公司 | zero sequence overcurrent protection method and device for transformer |
| CN210628922U (en) * | 2019-11-06 | 2020-05-26 | 珠海德鑫电气设备有限公司 | Hand-pulling mechanism for drawer of low-voltage switch cabinet |
| CN212277666U (en) * | 2020-06-16 | 2021-01-01 | 张志霞 | Electric power low-voltage switch cabinet |
| CN111711180A (en) * | 2020-06-19 | 2020-09-25 | 国网宁夏电力有限公司 | Method and system for preventing zero sequence overcurrent protection misoperation of ultrahigh voltage spare power automatic switching induced circuit |
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