CN114204518A - Zero sequence protection system for ungrounded system with new energy of 35kV or below - Google Patents
Zero sequence protection system for ungrounded system with new energy of 35kV or below Download PDFInfo
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- CN114204518A CN114204518A CN202111532733.6A CN202111532733A CN114204518A CN 114204518 A CN114204518 A CN 114204518A CN 202111532733 A CN202111532733 A CN 202111532733A CN 114204518 A CN114204518 A CN 114204518A
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- 238000001514 detection method Methods 0.000 claims abstract description 7
- 238000005259 measurement Methods 0.000 claims abstract description 4
- 238000000034 method Methods 0.000 claims description 3
- 238000009413 insulation Methods 0.000 description 4
- 238000010891 electric arc Methods 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 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
- 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
- H02H3/16—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 fault current to earth, frame or mass
- H02H3/162—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 fault current to earth, frame or mass for ac systems
- H02H3/165—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 fault current to earth, frame or mass for ac systems for three-phase systems
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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
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention discloses a zero sequence protection system of a new energy 35kV and the following ungrounded system in the technical field of new energy, which comprises: a line protection device; the circuit protection device is an RCS-9615C protection measurement and control device, the current sensor is a zero sequence current transformer, a detection end on the current sensor is connected to a switch cabinet, and the switch cabinet is a 35kV wind turbine busbar line switch cabinet.
Description
Technical Field
The invention relates to the technical field of new energy, in particular to a zero sequence protection system of an ungrounded system with new energy of 35kV or below.
Background
With the continuous development of the electrical discipline, more and more electrical technologies are applied in the real production. Aiming at a system with the new energy neutral point of 35kV or below, when the system is grounded in a single phase, fault line selection is difficult or line selection is inaccurate to cause misoperation due to small fault current. The commonly used 'switching-off method' is long in time for searching a fault point, and the reliability of power supply is seriously influenced. In the process, the single-phase grounding current and the network voltage are related to the size of the relative ground capacitance (namely the length of a line), and when the grounding current is large to a certain degree, the electric arc is difficult to extinguish, and a stable electric arc or an intermittent electric arc is formed. A stable arc may burn equipment or cause a two-phase, three-phase short circuit; intermittent arcs can cause the capacitance and the inductance of a power grid to form a resonant circuit to generate arc grounding overvoltage, so that the insulation of electrical equipment is endangered, and the safe operation of the whole system is influenced. Measures must be taken to address this. The utility model discloses the zero sequence protection function of using can effectively solve and amputate the trouble circuit fast when single-phase ground connection takes place at 35kV and following circuit, protection system's safe operation.
Disclosure of Invention
The invention aims to provide a zero sequence protection system of an ungrounded system with new energy of 35kV or below, which aims to solve the problem that the zero sequence protection function is applied to effectively solve the problem that a fault line is quickly cut off and the safe operation of the system is protected when a line with 35kV or below is grounded in a single phase.
In order to achieve the purpose, the invention provides the following technical scheme: a zero sequence protection system of new energy 35kV and the following ungrounded system comprises:
a line protection device;
a current sensor connected to the line protection device for performing detection of line single phase ground fault current.
Preferably, the line protection device is an RCS-9615C protection measurement and control device.
Preferably, the current sensor is a zero sequence current transformer.
Preferably, the detection end on the current sensor is connected to the switch cabinet.
Preferably, the switch cabinet is a 35kV wind turbine junction line switch cabinet.
Compared with the prior art, the invention has the beneficial effects that: the invention can accurately and rapidly judge the fault line when a single-phase earth fault occurs in an ungrounded system with the new energy of 35kV or below, and can cut off the fault line in a short time, thereby greatly shortening the overvoltage tolerance time of equipment, creating favorable conditions for reducing the insulation level of the system equipment and greatly increasing the running reliability of the system.
Drawings
FIG. 1 is a schematic structural view of the present invention;
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a zero sequence protection system of an ungrounded system of new energy 35kV or below, which can accurately and rapidly judge a fault line when the single-phase grounding fault occurs in the ungrounded system of new energy 35kV or below and cut off in a short time, greatly shorten the overvoltage tolerance time of equipment, create favorable conditions for reducing the insulation level of system equipment, greatly increase the reliability of system operation,
referring to fig. 1, the line protection device is an RCS-9615C protection measurement and control device;
referring to fig. 1 again, the current sensor is connected to the line protection device for performing detection of a single-phase ground fault current of the line, the current sensor is a zero sequence current transformer, a detection end of the current sensor is connected to a switch cabinet, and the switch cabinet is a 35kV wind turbine busbar switch cabinet.
Example 1
The total length of a main transformer 35kV side frame empty line is assumed to be 98.42 km;
the total length of a cable line at the 35kV side of a main transformer is 9.39km (an incoming cable is 2.55km, and a box-type transformer cable is 6.84 km);
35a3 line overhead line length: 16.27km (longest route);
35a3 line inbound cable length: 0.34 km; 35a3 box transformer cable length: 0.64 km;
line CT transformation ratio 35a 3: 300/5, taking the external zero sequence transformer current as the protection zero sequence current;
the single-phase normal capacitance current at the 35kV side of the main transformer in the maximum operation mode is
Ic＝[(35*98.42/350)+(95+1.44*300)*35/(2200+0.23*300)*2.55+(95+1.44*70)*35/(2200+0.23*70)*6.84]*1.25＝64.65A；
The normal single-phase capacitance current of the 35A3 line is
Ic-35A3＝[(35*16.27/350)+(95+1.44*300)*35/(2200+0.23*300)*0.34+(95
+1.44*70)*35/(2200+0.23*70)*0.64]*1.25＝7.96A
When the 35kV single-phase grounding outside the gap is carried out, the zero-sequence current of the 35A3 line is
I0-35A3＝7.96*3＝23.89A；
When the interval is 35kV single-phase grounding, the zero-sequence current of the 35A3 line is
I0-35A3＝64.65*3-23.89＝170.06A；
Zero sequence protection secondary constant value
The zero sequence protection acts on tripping, and is calculated according to the zero sequence current generated in the interval when the earth fault outside the interval is avoided, the reliability coefficient is 2.5, and the secondary zero sequence current fixed value is as follows:
i constant value0-35A3＝23.89*2.5/(300/5)＝1A；
According to the calculation formula, the rest lines are between 0.6 and 1, and because the 35A3 line is the longest line, the zero sequence current of the longest feeder line avoiding the line is set, namely all lines are 1A, and the time is 0 s.
In conclusion, the invention can accurately and rapidly judge the fault line when a single-phase earth fault occurs in an ungrounded system with the new energy of 35kV or below, and can cut off the fault line in a short time, so that the overvoltage enduring time of the equipment is greatly shortened, favorable conditions are created for reducing the insulation level of the system equipment, and the reliability of the system operation is greatly improved.
While the invention has been described above with reference to an embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the various features of the embodiments disclosed herein may be used in any combination, provided that there is no structural conflict, and the combinations are not exhaustively described in this specification merely for the sake of brevity and conservation of resources. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (5)
1. The zero sequence protection system for the ungrounded system with the new energy of 35kV and the following is characterized in that: the method comprises the following steps:
a line protection device;
a current sensor connected to the line protection device for performing detection of line single phase ground fault current.
2. The zero-sequence protection system of new energy 35kV and the following ungrounded system according to claim 1, characterized in that: the line protection device is an RCS-9615C protection measurement and control device.
3. The zero-sequence protection system of new energy 35kV and the following ungrounded system according to claim 2, characterized in that: the current sensor is a zero sequence current transformer.
4. The zero-sequence protection system of new energy 35kV and the following ungrounded system according to claim 3, characterized in that: and the detection end on the current sensor is connected to the switch cabinet.
5. The zero-sequence protection system of new energy 35kV and the following ungrounded system according to claim 4, characterized in that: the switch cabinet is a 35kV wind turbine junction line switch cabinet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111532733.6A CN114204518A (en) | 2021-12-15 | 2021-12-15 | Zero sequence protection system for ungrounded system with new energy of 35kV or below |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111532733.6A CN114204518A (en) | 2021-12-15 | 2021-12-15 | Zero sequence protection system for ungrounded system with new energy of 35kV or below |
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| Publication Number | Publication Date |
|---|---|
| CN114204518A true CN114204518A (en) | 2022-03-18 |
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| CN202111532733.6A Pending CN114204518A (en) | 2021-12-15 | 2021-12-15 | Zero sequence protection system for ungrounded system with new energy of 35kV or below |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104635107A (en) * | 2015-02-27 | 2015-05-20 | 国网福建晋江市供电有限公司 | Small-current grounding fault line selection system and line selection method |
| CN108279360A (en) * | 2018-03-29 | 2018-07-13 | 山东钢铁股份有限公司 | Singlephase earth fault circuit monitoring system |
| CN110554234A (en) * | 2019-09-03 | 2019-12-10 | 广东电网有限责任公司 | Zero-sequence current loop inspection method for in-service switch cabinet |
| CN214755500U (en) * | 2020-12-22 | 2021-11-16 | 青海盐湖工业股份有限公司 | Protection system for neutral point ungrounded power system |
-
2021
- 2021-12-15 CN CN202111532733.6A patent/CN114204518A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104635107A (en) * | 2015-02-27 | 2015-05-20 | 国网福建晋江市供电有限公司 | Small-current grounding fault line selection system and line selection method |
| CN108279360A (en) * | 2018-03-29 | 2018-07-13 | 山东钢铁股份有限公司 | Singlephase earth fault circuit monitoring system |
| CN110554234A (en) * | 2019-09-03 | 2019-12-10 | 广东电网有限责任公司 | Zero-sequence current loop inspection method for in-service switch cabinet |
| CN214755500U (en) * | 2020-12-22 | 2021-11-16 | 青海盐湖工业股份有限公司 | Protection system for neutral point ungrounded power system |
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