CN111756021A - Line protection current secondary circuit for three-half wiring - Google Patents
Line protection current secondary circuit for three-half wiring Download PDFInfo
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- CN111756021A CN111756021A CN202010601235.1A CN202010601235A CN111756021A CN 111756021 A CN111756021 A CN 111756021A CN 202010601235 A CN202010601235 A CN 202010601235A CN 111756021 A CN111756021 A CN 111756021A
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- 238000002955 isolation Methods 0.000 claims abstract description 24
- 239000013598 vector Substances 0.000 claims description 4
- 230000009471 action Effects 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 230000007257 malfunction Effects 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 5
- 238000012423 maintenance Methods 0.000 description 3
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000007935 neutral effect Effects 0.000 description 2
- 238000006386 neutralization reaction Methods 0.000 description 2
- 208000032368 Device malfunction Diseases 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
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Classifications
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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
- H02H7/22—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 distribution gear, e.g. bus-bar systems; for switching devices
- H02H7/226—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 distribution gear, e.g. bus-bar systems; for switching devices for wires or cables, e.g. heating wires
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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
- H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
Abstract
The invention relates to a line protection current secondary loop for three-half wiring, which comprises a first current transformer component, a second current transformer component and a line protection device, wherein the line protection device comprises a first isolation transmitter, a second isolation transmitter and a protection controller; the first current transformer assembly is used for detecting three-phase current of the first circuit breaker and outputting corresponding secondary side current; the first isolation transmitter is used for converting the secondary side current of the first current transformer assembly into a first three-phase current signal; the second current transformer assembly is used for detecting the three-phase current of the second circuit breaker and outputting the corresponding secondary side current; the second isolation transmitter is used for converting the secondary side current of the second current transformer assembly into a second three-phase current signal; the protection controller is used for calculating according to the first three-phase current signal and the second three-phase current signal to obtain a line three-phase current signal. The invention can avoid the malfunction of the protection device caused by multipoint grounding of the current loop.
Description
Technical Field
The invention relates to the technical field of current transformers, in particular to a line protection current secondary circuit for three-half wiring.
Background
3/2 in the wiring mode, 3 breakers among 2 buses are connected in series to form a string. The elements are led out from between 2 adjacent circuit breakers in a string, i.e. 3 circuit breakers supply two elements, the intermediate circuit breaker is shared, corresponding to 1.5 circuit breakers for each element, and is therefore also referred to as a half-breaker connection. Compared with the double-bus mode with the bypass bus and the like, the 3/2 circuit breaker wiring mode has the advantages of reliability, convenience in operation, flexible operation mode and the like, and the power failure range can be greatly reduced or even the load can not be lost when a line or bus fails. Therefore, three-half wiring is widely used in 500kV systems. 3/2 the circuit breaker is connected in series by three circuit breakers to lead out two outgoing lines, and connected to two groups of bus lines (called as a string). In the 3/2 breaker connection, the two breakers connected to the bus are called bus breakers or side breakers, and the middle breaker is called a middle breaker or tie breaker.
As shown in figure 1, an 3/2 wiring mode is adopted, when any one of 5051, 5052 and 5053 circuit breakers is overhauled, a #3 main transformer and a 500kV A line can normally operate and supply power. In order to match the flexibility of a three-second main connection mode, secondary currents of current transformers adopted by devices operating in the main connection mode, such as interval monitoring, control and protection devices, need to be acquired simultaneously from the current transformers of two adjacent circuit breakers, for example, the secondary currents of the current transformers of 5052 and 5053 circuit breakers are acquired by first line protection respectively. Therefore, when any one of the 5052 circuit breaker or the 5053 circuit breaker is overhauled, the line A protection can collect the current of the full-flowing line. In the specific implementation of the current secondary circuit, current transformers of adjacent circuit breakers are connected in parallel and then connected into a protection device, and the secondary side of the current transformer is connected in parallel to form a sum current, as shown in fig. 2. Because the secondary circuits of the current transformers of the adjacent circuit breakers are connected in parallel, the electrical circuits are connected, and current can flow in the two current circuits.
When the current transformer normally operates, because the internal resistance of the current transformer body is close to infinity, the internal resistances of the secondary protection device and the loop are very small, and the secondary current of the current transformer can still normally flow into the secondary protection device from the current transformer. In order to prevent high voltage on the primary side from being serially connected into a secondary circuit through a current transformer and damaging personal safety of the secondary circuit and electrical operation personnel, the secondary circuit of the current transformer is provided with a grounding point, as shown in the attached figure 2, the grounding point of the secondary circuit of the current transformer is protected by a first line at a terminal row of a circuit protection device, when one circuit breaker is overhauled, particularly, the current transformer for overhauling the circuit breaker has corresponding work, if the secondary circuit of the current transformer is overhauled to have a point grounding, the secondary current of the current transformer of the circuit breaker which runs can be led to circulate through a plurality of grounding points, and the secondary current can not flow into the protection device any more. Therefore, the interval protection device can trip the circuit breaker on the side and the circuit breaker on the opposite side by false operation. 500kV protection misoperation caused by multipoint grounding of a secondary circuit of a current transformer occurs, and in recent years, more than ten 500kV interval protection misoperation events caused by multipoint grounding of the current transformer during maintenance of a circuit breaker occur in a certain large-scale power grid, so that great economic loss and great adverse social influence are caused. At present, the control measure for the problem is to post warning marks on the site, strengthen the technical training of personnel and standardize the steps of site operation. Although the on-site attention mark pasting measures can be applied to all operators, the on-site attention mark pasting measures as a passive control measure cannot ensure that the on-site operators can view the attention marks carefully. The technical training of personnel is strengthened, the field operation step measures are standardized, and the influences of various factors such as the technical level of operators, the working experience, the field state of the operators and the like also exist.
In summary, the prior art cannot fundamentally solve the problem of malfunction of the protection device caused by multipoint grounding of the three-second wiring current loop.
Disclosure of Invention
The invention aims to provide a line protection current secondary circuit for three-half wiring, which is used for solving the technical problem that the prior art cannot fundamentally solve the malfunction of a protection device caused by multipoint grounding of the three-half wiring current circuit.
In order to achieve the above object, an embodiment of the present invention provides a line protection current secondary circuit for three-half wiring, including a first current transformer assembly, a second current transformer assembly, and a line protection device, where the line protection device includes a first isolation transmitter, a second isolation transmitter, and a protection controller;
the first current transformer assembly is connected with the first circuit breaker and is used for detecting the three-phase current of the first circuit breaker and outputting the corresponding secondary side current; the first isolation transmitter is used for converting the secondary side current of the first current transformer assembly into a first three-phase current signal which can be processed by the protection controller;
the second current transformer assembly is connected with the second circuit breaker and is used for detecting the three-phase current of the second circuit breaker and outputting the corresponding secondary side current; the second isolation transmitter is used for converting the secondary side current of the second current transformer assembly into a second three-phase current signal which can be processed by the protection controller; the first circuit breaker and the second circuit breaker are two adjacent circuit breakers in a three-half connection;
the protection controller is used for calculating according to the first three-phase current signal and the second three-phase current signal to obtain a three-phase current signal of the line, and controlling the protection device to execute line protection action according to the three-phase current signal of the line and preset logic.
The protection controller is specifically configured to sum each phase current signal of the first three-phase current signal and each phase current signal of the second three-phase current signal to obtain a three-phase current signal of the line.
The first current transformer assembly comprises a first A-phase current transformer, a first B-phase current transformer and a first C-phase current transformer, and the second current transformer assembly comprises a second A-phase current transformer, a second B-phase current transformer and a second C-phase current transformer.
Wherein the protection controller comprises a memory and a processor, the memory having stored therein computer readable instructions that, when executed by the processor, cause the processor to perform the steps of:
receiving a first three-phase current signal transmitted by the first isolation transmitter
And a second three-phase current signal transmitted by the second isolation transmitter
According to the first three-phase current signal
And a second three-phase current signal
Three-phase current signal of line after vector summation
Wherein the content of the first and second substances,
compared with the prior art, the embodiment of the invention has the following beneficial effects:
because under the current three-second wiring mode, the protection device adopts the mode that a plurality of current transformer secondary circuits are connected in parallel to carry out current neutralization in time, when one current transformer is overhauled, the secondary circuit multipoint grounding caused by reasons such as error touch of maintainers can cause misoperation of the protection device, and the secondary current neutralization mode of a plurality of current transformers is changed, namely, each current transformer is independently accessed into the protection device to carry out software summation of the protection device, thereby fundamentally avoiding the condition that the current transformer secondary circuit multipoint grounding causes protection misoperation and avoiding large electric power accidents.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a three-half wiring.
FIG. 2 is a schematic diagram of a protection current secondary circuit of a three-half wiring line.
Fig. 3 is a schematic diagram of protection malfunction caused by multipoint grounding of a conventional three-in-two current transformer.
Fig. 4 is a wiring diagram of a secondary circuit of a three-half wiring current transformer according to an embodiment of the invention.
Detailed Description
Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
In addition, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without some of these specific details. In some instances, well known means have not been described in detail so as not to obscure the present invention.
The embodiment of the invention provides a line protection current secondary loop for three-half wiring, which comprises a first current transformer assembly, a second current transformer assembly and a line protection device, wherein the line protection device comprises a first isolation transmitter, a second isolation transmitter and a protection controller;
the first current transformer assembly is connected with the first circuit breaker and is used for detecting the three-phase current of the first circuit breaker and outputting the corresponding secondary side current; the first isolation transmitter is used for converting the secondary side current of the first current transformer assembly into a first three-phase current signal which can be processed by the protection controller;
the second current transformer assembly is connected with the second circuit breaker and is used for detecting the three-phase current of the second circuit breaker and outputting the corresponding secondary side current; the second isolation transmitter is used for converting the secondary side current of the second current transformer assembly into a second three-phase current signal which can be processed by the protection controller; the first circuit breaker and the second circuit breaker are two adjacent circuit breakers in a three-half connection;
the protection controller is used for calculating according to the first three-phase current signal and the second three-phase current signal to obtain a three-phase current signal of the line, and controlling the protection device to execute line protection action according to the three-phase current signal of the line and preset logic.
The protection controller is specifically configured to sum each phase current signal of the first three-phase current signal and each phase current signal of the second three-phase current signal to obtain a three-phase current signal of the line.
The first current transformer assembly comprises a first A-phase current transformer, a first B-phase current transformer and a first C-phase current transformer, and the second current transformer assembly comprises a second A-phase current transformer, a second B-phase current transformer and a second C-phase current transformer.
In this embodiment, a detailed explanation is made with reference to the three-second wiring diagram shown in fig. 1, in order to match the flexibility of the three-second wiring scheme, the secondary currents of the current transformers adopted by the devices for interval monitoring, control, protection and the like operating in the main wiring scheme of fig. 1 need to be collected from the current transformers of two adjacent circuit breakers at the same time, that is, the current transformers of the adjacent circuit breakers are connected in parallel to form a sum current on the current secondary circuit, and then the sum current is sent to the line protection device. Because the secondary circuits of the current transformers of the adjacent circuit breakers are connected in parallel, the electrical circuits are connected, and current can flow in the two current circuits. When one secondary loop of the current transformer has an earthing point, the current in the secondary loop circulates through the earthing points, and the protection device collects incomplete current to cause protection misoperation. As shown in fig. 2, when the circuit breakers 5052 and 5053 are in normal operation, the 5052 circuit breaker a-phase current transformer 52LHa transmits the secondary current to the protection device through a secondary circuit a4521, meets the 5053 circuit breaker a-phase current transformer 53LHa through the secondary circuit a4531 in the secondary circuit, and the two currents are superposed and then sent to the protection device, so that the protection device can correctly collect the interval current, and the protection device can correctly act.
It should be noted that when one breaker in the three-half connection is repaired, the corresponding current transformer is also stopped, but the secondary circuit is also in an operating state because of being connected with the current transformer in operation. Because the internal resistance of the current transformer body is close to infinity, the current of the current transformer in operation can be completely transmitted to the protection device after the current transformer is stopped. If more than one grounding point appears in the secondary loop of the shutdown current transformer, the current of the operation current transformer is shunted. As shown in fig. 2, the current transformer of the 5052 circuit breaker is stopped for maintenance work, and the current transformer of the 5053 circuit breaker is normally operated. Originally, there was only one grounding point in the current secondary, namely K1. When another grounding point K2 appears in the secondary circuit of the current transformer of the 5052 circuit breaker due to misoperation of maintenance workers and the like, the current in the secondary circuit changes. As shown in fig. 3, taking the current transformer a phase current of the 5053 circuit breaker as an example for explanation, after being output by the current transformer 53LHa, the secondary current is transmitted to the protection device side through the secondary circuit a4531 ((c) in the figure), reaches the parallel connection part (c) in the figure), passes through the current transformer secondary circuit a4521 ((c) in the figure) of the 5052 circuit breaker, flows to the ground through the grounding point K2 ((c) in the figure), returns to the secondary circuit through the original grounding point K1 ((c) in the figure), and flows back to the current transformer neutral line circuit N4531 (r) of the 5053 circuit breaker through the common current neutral line, and finally flows into the current transformer to form a closed circuit. It can be seen that the current which is originally required to be transmitted to the protection device forms a closed loop through a plurality of grounding points and the ground, the current cannot flow into the protection device, and the protection device malfunctions due to incorrect collected current.
Based on the above analysis, in the traditional three-second connection mode, the secondary current of the protection device is electrically summed by connecting a plurality of current transformers in parallel through a secondary circuit, so that each current transformer is directly electrically connected, which is also the essential reason for causing malfunction of the protection device. Therefore, the present embodiment provides a line protection current secondary circuit structure as shown in fig. 4, which changes the electrical connection of the current transformers to prevent the current transformers from being electrically connected, and performs current summation of a plurality of current transformers on software through a protection device, thereby fundamentally solving the malfunction of the protection device caused by multipoint grounding of the secondary circuit of the current transformers.
Referring to fig. 4, the 500kV first line needs to collect the secondary side currents of the current transformer assemblies of the 5052 circuit breaker and the 5053 circuit breaker at the same time, and the secondary circuits of the current transformer assemblies are firstly separated and respectively connected to the line protection device. The secondary side current of the first current transformer assembly of the 5052 circuit breaker is connected to the line protection device terminals 1ID1, 1ID3, 1ID5 and 1ID7 through a current secondary loop, and then a current signal is converted into a small signal which can be processed by the line protection device through a first isolation transmitter in the line protection device. The secondary side current of the second current transformer assembly of the 5053 circuit breaker is connected to the line protection device terminals 1ID9, 1ID11, 1ID13 and 1ID15 through a current secondary loop, and then a current signal is converted into a small signal which can be processed by the line protection device through a first isolation transmitter in the line protection device. The secondary side current of the current transformer assembly of the 5052 circuit breaker may form a secondary loop one-point grounding point K1 at the protection or at the body of the current transformer assembly, and the secondary side current of the second current transformer assembly of the 5053 circuit breaker may also form a secondary loop one-point grounding point K2 at the protection or at the body of the current transformer assembly. The grounding point K1 and the grounding point K2 are isolated from each other, so that no electrical connection exists.
Wherein the first current transformer assembly includes a first a-phase current transformer 52LHa, a first B-phase current transformer 52LHb and a first C-phase current transformer 52LHc, and the second current transformer assembly includes a second a-phase current transformer 53LHa, a second B-phase current transformer 53LHb and a second C-phase current transformer 53 LHc.
Wherein the protection controller comprises a memory and a processor, the memory having stored therein computer readable instructions that, when executed by the processor, cause the processor to perform the steps of:
receiving a first three-phase current signal transmitted by the first isolation transmitter
And a second three-phase current signal transmitted by the second isolation transmitter
According to the first three-phase current signal
And a secondThree phase current signal
Three-phase current signal of line after vector summation
Wherein the content of the first and second substances,
the current amounts are vectors and include magnitude and phase of current assignments.
As can be seen from the above description of the embodiments, the embodiments of the present invention have the following advantages:
(1) each current transformer is independently connected to a protection device and the software of the protection device is summed, so that the condition of protection misoperation caused by multipoint grounding of a secondary circuit of the current transformer is fundamentally avoided, and a large electric power accident is avoided. .
(2) The current-summing circuit can be widely applied to the condition of adopting three-half wiring and can also be applied to other conditions needing to sum currents by a plurality of current transformers.
(3) When the problem of protection misoperation caused by multipoint grounding of the secondary circuit of the upper current transformer is solved, only one protection channel needs to be added to the protection device and software summation calculation is carried out, the function of traditional current parallel connection can be completely realized, and the problem of protection misoperation caused by multipoint grounding is fundamentally solved.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (4)
1. A line protection current secondary loop for three-half wiring is characterized by comprising a first current transformer component, a second current transformer component and a line protection device, wherein the line protection device comprises a first isolation transmitter, a second isolation transmitter and a protection controller;
the first current transformer assembly is connected with the first circuit breaker and is used for detecting the three-phase current of the first circuit breaker and outputting the corresponding secondary side current; the first isolation transmitter is used for converting the secondary side current of the first current transformer assembly into a first three-phase current signal which can be processed by the protection controller;
the second current transformer assembly is connected with the second circuit breaker and is used for detecting the three-phase current of the second circuit breaker and outputting the corresponding secondary side current; the second isolation transmitter is used for converting the secondary side current of the second current transformer assembly into a second three-phase current signal which can be processed by the protection controller; the first circuit breaker and the second circuit breaker are two adjacent circuit breakers in a three-half connection;
the protection controller is used for calculating according to the first three-phase current signal and the second three-phase current signal to obtain a three-phase current signal of the line, and controlling the protection device to execute line protection action according to the three-phase current signal of the line and preset logic.
2. The three-half wired line protection current secondary circuit of claim 1, wherein said protection controller is specifically configured to sum each phase current signal of said first three phase current signal and said second three phase current signal to obtain a three phase current signal of the line, respectively.
3. The line protection current secondary circuit for a three-half connection of claim 1, wherein the first current transformer assembly includes a first a-phase current transformer, a first B-phase current transformer, and a first C-phase current transformer, and the second current transformer assembly includes a second a-phase current transformer, a second B-phase current transformer, and a second C-phase current transformer.
4. The line protection current secondary loop for a three-half wire connection of claim 2, wherein said protection controller includes a memory and a processor, said memory having stored therein computer readable instructions that, when executed by said processor, cause said processor to perform the steps of:
receiving a first three-phase current signal transmitted by the first isolation transmitter
And a second three-phase current signal transmitted by the second isolation transmitter
According to the first three-phase current signal
And a second three-phase current signal
Three-phase current signal of line after vector summation
Wherein the content of the first and second substances,
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010601235.1A CN111756021A (en) | 2020-06-29 | 2020-06-29 | Line protection current secondary circuit for three-half wiring |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010601235.1A CN111756021A (en) | 2020-06-29 | 2020-06-29 | Line protection current secondary circuit for three-half wiring |
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| CN111756021A true CN111756021A (en) | 2020-10-09 |
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| CN202010601235.1A Pending CN111756021A (en) | 2020-06-29 | 2020-06-29 | Line protection current secondary circuit for three-half wiring |
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| EP3340746A1 (en) * | 2016-12-22 | 2018-06-27 | Technische Hochschule Mittelhessen | Control unit for controlling a high frequency generator |
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| CN101097818A (en) * | 2006-06-29 | 2008-01-02 | Abb技术有限公司 | Distance protection relay and method |
| CN102043085A (en) * | 2010-10-12 | 2011-05-04 | 河南省电力公司南阳供电公司 | Ultrahigh voltage power grid and current on-load detector |
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Application publication date: 20201009 |