CN106486898B - Circuit safety design method in secondary circuit of nuclear power plant switch cabinet - Google Patents
Circuit safety design method in secondary circuit of nuclear power plant switch cabinet Download PDFInfo
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- CN106486898B CN106486898B CN201610911594.0A CN201610911594A CN106486898B CN 106486898 B CN106486898 B CN 106486898B CN 201610911594 A CN201610911594 A CN 201610911594A CN 106486898 B CN106486898 B CN 106486898B
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- safety
- circuit
- sequence current
- zero sequence
- switch cabinet
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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
- H02B1/24—Circuit arrangements for boards or switchyards
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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 circuit safety design method in a secondary circuit of a switch cabinet of a nuclear power plant, which is characterized in that two independent zero sequence current transformers are arranged in a feeder circuit of the secondary circuit of a safety-level emergency switch cabinet, zero sequence current participating in an overcurrent protection function is led from a first zero sequence current transformer, and zero sequence current participating in a grounding line selection function is led from a second zero sequence current transformer. The circuit design of the invention can ensure that the secondary side of the zero sequence current transformer is short-circuited at the non-safety-level line selection screen when the comprehensive protection device realizes the safety level function, thereby avoiding the influence of the non-safety-level circuit on the safety level circuit to execute the safety function.
Description
Technical Field
The invention belongs to a switch cabinet circuit design technology, and particularly relates to a circuit safety design method in a secondary circuit of a switch cabinet of a nuclear power plant.
Background
The electrical switchgear comprises primary equipment and secondary equipment, wherein the primary equipment is a main body forming an electric power system and is mainly used for directly producing, conveying and distributing electric energy, and the secondary equipment is used for controlling, regulating, protecting and detecting the primary equipment.
The design of all electrical circuits of a nuclear power plant is based on their safety importance, and according to the classification principle of electrical systems and devices, all devices and components of the electrical systems which participate in protecting the public under accident conditions are defined as 1E safety class, and when a single fault which may affect one system to perform its function and the loss of off-plant power occur, the safety class electrical system must ensure that its function is available, so that the safety class devices should be designed redundantly so that any single fault does not cause the loss of function, wherein faults occurring inside the system, faults which may occur in auxiliary systems, and faults caused by external disasters should be considered. Devices and components that do not belong to a security level function are defined as non-security levels. A failure of the non-safety level electrical loop should not affect the safety level electrical loop as required by the isolation criteria.
In the secondary circuit design of the safety level emergency switch cabinet of the nuclear power plant, zero sequence current at the feeder side participates in zero sequence overcurrent protection to execute alarm or trip operation, and is sent to a small current line selection device to participate in the operation of a line selection screen. However, the two functions involved in zero sequence current belong to different safety levels, the function involved in overcurrent protection belongs to a safety level, and the function involved in line selection belongs to a non-safety level. Here, there is an intersection between the safety circuit and the non-safety circuit at the zero sequence current transformer of the feeder line, and the safety circuit may be affected by the non-safety circuit.
Disclosure of Invention
The invention aims to provide a circuit safety design method in a secondary circuit of a switch cabinet of a nuclear power plant, which avoids the influence of a non-safety circuit on the execution safety function of a safety circuit.
The technical scheme of the invention is as follows: a circuit safety design method in a secondary circuit of a nuclear power plant switch cabinet is characterized in that two independent zero sequence current transformers are arranged in a feeder circuit of the secondary circuit of a safety emergency switch cabinet, zero sequence current participating in an overcurrent protection function is led from a first zero sequence current transformer, and zero sequence current participating in a grounding line selection function is led from a second zero sequence current transformer.
Further, according to the method for designing the safety of the circuit in the secondary circuit of the nuclear power plant switch cabinet, the transformation ratio and the capacity of the two zero sequence current transformers are completely the same.
Furthermore, the two zero sequence current transformers are products of the same manufacturer and the same batch.
Further, according to the method for designing the circuit safety in the secondary circuit of the nuclear power plant switch cabinet, the secondary line of the first zero sequence current transformer is introduced into the comprehensive protection device of the switch cabinet, and the secondary line of the second zero sequence current transformer is introduced into the small current line selection device.
Further, according to the circuit safety design method in the secondary circuit of the nuclear power plant switch cabinet, the two independent zero sequence current transformers are installed in the small feed line side wiring chamber of the safety emergency switch cabinet.
The invention has the following beneficial effects: according to the invention, two independent zero sequence current transformers are arranged in a feeder line loop of a switch cabinet secondary loop, when a first zero sequence current transformer connected with the comprehensive protection device detects a single-phase earth fault, the comprehensive protection device realizes the safety level function of an overcurrent fault tripping contactor, and at the moment, a second zero sequence current transformer secondary side connected with a small current line selection device is in short circuit at a non-safety level line selection screen, so that a larger feedback current can not be fed back to a safety level circuit, thereby avoiding the false operation of a safety level switch cabinet.
Drawings
FIG. 1 is a schematic diagram of a mounting principle of a zero sequence current transformer of a safety-class switch cabinet;
FIG. 2-1 is a schematic diagram of a wiring manner of a zero sequence current transformer performing a safety class function;
fig. 2-2 is a schematic diagram of a wiring manner of a zero-sequence current transformer for performing a non-safety level function.
Detailed Description
The invention is described in detail below with reference to the figures and examples.
The invention relates to a circuit safety design method in a secondary circuit of a switch cabinet of a nuclear power plant, wherein two zero sequence current transformers with the same capacity and transformation ratio are arranged in a feeder circuit of the secondary circuit of a safety emergency switch cabinet, the zero sequence current participating in an overcurrent protection function is led from one zero sequence current transformer, and the zero sequence current participating in a grounding line selection function is led from the other zero sequence current transformer.
The specific design scheme of the secondary circuit of the safety-level emergency switch cabinet is as follows:
in the original design of the secondary circuit of the switch cabinet, a zero sequence current transformer with two secondary coils is usually installed. The two secondary coils are respectively used for ground fault protection and ground line selection. Since the ground fault protection performs a safety function, the ground select function performs a non-safety level function. The installation of a zero sequence current transformer can cause the safety circuit and the non-safety circuit to be crossed on the primary side of the zero sequence current transformer of the feeder line, and the safety circuit can be influenced by the non-safety circuit.
The main idea of the invention is to install two independent zero sequence current transformers 007TI and 008TI on a feeder line side wiring small chamber of a safety level emergency switch cabinet as shown in figure 1. In order to avoid measurement errors caused by the self difference of the transformers, the transformation ratio and the capacity of the two zero sequence current transformers should be completely the same, and products of the same manufacturer and the same batch should be selected as much as possible.
The zero sequence current transformer 007TI secondary line for executing the safety level function is introduced into a comprehensive protection device 001XI of the switch cabinet, as shown in figure 2-1; the zero sequence current transformer 008TI secondary line performing the non-safety level function is introduced into a small current line selection device as shown in fig. 2-2.
In a safety-level switch cabinet, when a zero-sequence current transformer 007TI of the switch cabinet detects a single-phase ground fault, an outlet relay of a comprehensive protection device 001XI acts to cause a contactor 001JA to be opened, so that the safety-level function of tripping the contactor through an overcurrent fault is realized.
At the moment, an overcurrent signal detected by the other zero-sequence current transformer 008TI is sent to a non-safety-level small current line selection device, and the overcurrent signal is received by a line selection screen and is subjected to logic processing.
Because the two current transformers are independently arranged, the secondary side of the zero sequence current transformer is in short circuit at the non-safety-level line selection screen, and larger transmitted current cannot be fed back to the safety-level circuit, so that the false operation of the safety-level switch cabinet is avoided.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations.
Claims (4)
1. A circuit safety design method in a secondary circuit of a nuclear power plant switch cabinet is characterized by comprising the following steps: two independent zero sequence current transformers are arranged in a feeder line loop of a secondary loop of a safety level emergency switch cabinet, zero sequence current participating in an overcurrent protection function is led from a first zero sequence current transformer, zero sequence current participating in a grounding line selection function is led from a second zero sequence current transformer, a secondary line of the first zero sequence current transformer is led into a comprehensive protection device of the switch cabinet, and a secondary line of the second zero sequence current transformer is led into a small current line selection device.
2. The method for designing the safety of the circuit in the secondary circuit of the nuclear power plant switchgear according to claim 1, characterized in that: the transformation ratio and the capacity of the two zero sequence current transformers are completely the same.
3. The method for designing the safety of the circuit in the secondary circuit of the nuclear power plant switchgear according to claim 2, characterized in that: the two zero sequence current transformers are products of the same manufacturer and the same batch.
4. The method for designing the safety of the circuit in the secondary circuit of the nuclear power plant switchgear according to claim 1, characterized in that: the two independent zero sequence current transformers are arranged in a feeder line side wiring small chamber of the safety emergency switch cabinet.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610911594.0A CN106486898B (en) | 2016-10-19 | 2016-10-19 | Circuit safety design method in secondary circuit of nuclear power plant switch cabinet |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610911594.0A CN106486898B (en) | 2016-10-19 | 2016-10-19 | Circuit safety design method in secondary circuit of nuclear power plant switch cabinet |
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| CN106486898A CN106486898A (en) | 2017-03-08 |
| CN106486898B true CN106486898B (en) | 2020-11-17 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108279360A (en) * | 2018-03-29 | 2018-07-13 | 山东钢铁股份有限公司 | Singlephase earth fault circuit monitoring system |
| CN109103841B (en) * | 2018-10-30 | 2019-08-30 | 攀钢集团西昌钢钒有限公司 | A kind of electric system of supply transformer |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104659777A (en) * | 2014-11-19 | 2015-05-27 | 国家电网公司 | Small current grounding device for 10KV line of 35KV transformer substation |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104659777A (en) * | 2014-11-19 | 2015-05-27 | 国家电网公司 | Small current grounding device for 10KV line of 35KV transformer substation |
Non-Patent Citations (1)
| Title |
|---|
| 国内某核电厂中压厂用电系统中性点接地方式研究;费云艳，车皓;《电器工业》;20140831;第67-71页 * |
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